{"messages": [{"role": "assistant", "content": "Among the great and fertile scientific conceptions which have either originated or become firmly established during the nineteenth century, the theory of evolution, if not the greatest of them all, will certainly take its place in the front rank. As a partial explanation (for no complete explanation is possible to finite intelligence) of the phenomena of nature, it illuminates every department of science, from the study of the most remote cosmic phenomena accessible to us to that of the minutest organisms revealed by the most powerful microscopes; while upon the great problem of the mode of origin of the various forms of life—long considered insoluble—it throws so clear a light that to many biologists it seems to afford as complete a solution, in principle, as we can expect to reach. THE NATURE AND LIMITS OF EVOLUTION \nSo many of the objections which are still made to the theory of evolution, and especially to that branch of it which deals with living organisms, rest upon a misconception of what it professes to explain, and even of what any theory can possibly explain, that a few words on its nature and limits seem to be necessary. Evolution, as a general principle, implies that all things in the universe, as we see them, have arisen from other things which preceded them by a process of modification, under the action of those all-pervading but mysterious agencies known to us as “natural forces,” or, more generally, “the laws of nature.” More particularly the term evolution implies that the process is an “unrolling,” or “unfolding,” derived probably from the way in which leaves and flowers are usually rolled up or crumpled up in the bud and grow into their perfect form by unrolling or unfolding. Insects in the pupa and vertebrates in the embryo exhibit a somewhat similar condition of folding, and the word is therefore very applicable to an extensive range of phenomena; but it must not be taken as universally applicable, since in the material world there are other modes of orderly change under natural laws to which the terms development or evolution are equally applicable. The “continuity” of physical phenomena, as illustrated by the late Sir William Grove in 1866, has the same general meaning, but evolution implies more than mere continuity or succession—something like growth or definite change from form to form under the action of unchangeable laws."}]}
{"messages": [{"role": "assistant", "content": "The “continuity” of physical phenomena, as illustrated by the late Sir William Grove in 1866, has the same general meaning, but evolution implies more than mere continuity or succession—something like growth or definite change from form to form under the action of unchangeable laws. The point to be especially noted here is, that evolution, even if it is essentially a true and complete theory of the universe, can only explain the existing conditions of nature by showing that it has been derived from some pre-existing condition through the action of known forces and laws. It may also show the high probability of a similar derivation from a still earlier condition; but the further back we go the more uncertain must be our conclusions, while we can never make any real approach to the absolute beginnings of things. Herbert Spencer, and many other thinkers before him, have shown that if we try to realize the absolute nature of the simplest phenomena, we are inevitably landed either in a contradiction or in some unthinkable proposition. Thus, suppose we ask, Is matter infinitely divisible, or is it not? If we say it is, we cannot think it out, since all infinity, however it may be stated in words, is really unthinkable."}]}
{"messages": [{"role": "assistant", "content": "If we say it is, we cannot think it out, since all infinity, however it may be stated in words, is really unthinkable. If we say there is a limit—the ultimate atom—then, as all size is comparative, we can imagine a being to whom this atom seems as large as an apple or even a house does to us; and we then find it quite unthinkable that this mass of matter should be in its nature absolutely indivisible even by an infinite force. It follows that all explanations of phenomena can only be partial explanations. They can inform us of the last change or the last series of changes which brought about the actual conditions now existing, and they can often enable us to predict future changes to a limited extent; but both the infinite past and the remote future are alike beyond our powers. Yet the explanations that the theory of evolution gives us are none the less real and none the less important, especially when we compare its teachings with the wild guesses or the total ignorance of the thinkers of earlier ages. THE RISE AND PROGRESS OF THE IDEA OF EVOLUTION \nIf we trace, however briefly, the gradual development of knowledge and speculation on this subject, we shall perhaps appreciate more fully the advance we have really made during the present century."}]}
{"messages": [{"role": "assistant", "content": "THE RISE AND PROGRESS OF THE IDEA OF EVOLUTION \nIf we trace, however briefly, the gradual development of knowledge and speculation on this subject, we shall perhaps appreciate more fully the advance we have really made during the present century. The first speculations on the nature and source of the phenomena of the universe, of which we have any knowledge, are those of the early Greek philosophers, such as Thales, Anaximander, Anaxagoras, and Empedocles; but as the more important of their teachings are embodied, with some approach to system and with much acuteness of reasoning, in the great poem of the Latin author Lucretius, “On the Nature of Things,” it will be sufficient to give a sketch of his main conclusions, making use of the excellent prose translation by Mr. H. A. J. Munro, of Trinity College, Cambridge."}]}
{"messages": [{"role": "assistant", "content": "Munro, of Trinity College, Cambridge. Lucretius had a very clear idea of the indestructibility of matter. He argues that things cannot have come out of nothing, and he says: “A thing never returns to nothing, but all things, after disruption, go back into the first bodies of matter.” He then argues that, as the actual processes of growth, decay, and other natural changes are imperceptible to us, therefore “Nature works by unseen bodies.” He justly claims great importance for the demonstration of the fact that in all matter whatever, however solid and hard it may be, there are vacancies, or, as he expresses it, “Mixed up in all things there is void or empty space.” He thus anticipated the modern doctrine that the molecules of matter do not come into actual contact. He then defines atoms thus: “First bodies are solid and without void”; and as nothing can be produced from nothing, he concludes that these first bodies (atoms or molecules) must be everlasting, and that they supply matter for the reproduction of all things. He then goes on to prove that these “first beginnings are of solid singleness, not formed of parts, but strong in everlasting singleness.” He further proves that these “first beginnings” (atoms) cannot be infinitely small, and also that the universe cannot be limited—that it is infinite. He thus anticipated the main ideas as to atoms and the universe which have been held by most materialistic thinkers down to our own times."}]}
{"messages": [{"role": "assistant", "content": "He thus anticipated the main ideas as to atoms and the universe which have been held by most materialistic thinkers down to our own times. Lucretius was an absolute materialist, for though he did not deny the existence of the gods he refused them any share in the construction of the universe, which, he again and again urges, arose by chance, after infinite time, by the random motions and collisions and entanglements of the infinity of atoms. He assumes some forces analogous to gravitation and the molecular motions of gases in the following passage: “For the first beginnings of things move first of themselves; next these bodies which form a small aggregate and come nearest, so to say, to the powers of the first beginnings are impelled and set in movement by the unseen strokes of these first bodies, and they next in turn stir up other bodies which are a little larger.” \nHe also anticipated Galileo as to the equal speed of all falling bodies when not checked by the air in the following precise statement: “For whenever bodies fall through water and thin air they must quicken their descents in proportion to their weights, because the body of water and subtle nature of air cannot retard everything to an equal degree; on the other hand, empty void cannot offer resistance to anything in any direction at any time, but must continually give way; and for this reason all things must be moved and borne along with equal velocity, though of unequal weights, through the unresisting void.” \nThis is a wonderfully accurate general statement of the equal rate of motion of all kinds of matter under the same forces; and when we consider that there is no indication of any experimental basis for this conclusion, and that nothing equivalent to our sciences of physics or chemistry existed, we are amazed at the general correctness of many of his views, derived solely by a process of reasoning from the most obvious phenomena of nature. He argues that, given infinite matter and space and inherent motion, “things must go on and be completed,” and his general conclusion is thus expressed: “If you will apprehend and keep in mind these things, nature, free at once and rid of her haughty lords, is seen to do all things spontaneously of herself without the meddling of the gods.” \nIt is when he attempts to deal with the origin of living organisms that the absence of all knowledge of chemistry, physiology, and histology renders his task impossible and leads him into what seem to us the wildest absurdities. He has an elaborate but very unconvincing argument that sensation can arise out of atoms which have no sensation; and, taking the appearance of worms, etc., in the earth and in putrid matter as a proof that they are still actually produced _de novo_ in it, he argues that at some remote epoch the now worn-out earth was more fertile, and produced in like manner all kinds of animals. The first human infants he supposes to have been formed at some very remote time in the manner following: “For much heat and moisture would then abound in the fields; and therefore wherever a suitable spot offered wombs would grow, attached to the earth by roots; and when the warmth of the infants, flying the wet and craving the air, had opened these in the fulness of time, nature would turn to that spot the pores of the earth and constrain it to yield from its opened veins a liquid most like to milk."}]}
{"messages": [{"role": "assistant", "content": "The first human infants he supposes to have been formed at some very remote time in the manner following: “For much heat and moisture would then abound in the fields; and therefore wherever a suitable spot offered wombs would grow, attached to the earth by roots; and when the warmth of the infants, flying the wet and craving the air, had opened these in the fulness of time, nature would turn to that spot the pores of the earth and constrain it to yield from its opened veins a liquid most like to milk. To the children the earth would furnish food, the heat raiment, the grass a bed rich in abundance of soft down.... Wherefore, again and again I say, the earth, with good title, has gotten and keeps the name of mother, since she of herself gave birth to mankind, and at a time nearly fixed shed forth every beast that ranges wildly over the great mountains, and at the same time the fowls of the air with all their varied shapes.” \nThe fact that this mode of origin commended itself to one of the brightest intellects of the first century B. C., enlightened by the best thought of the Grecian philosophers, may enable us the better to appreciate the immense advance made by modern evolutionists. THE FIRST REAL STEPS TOWARDS EVOLUTION \nWe have now a great blank of fifteen centuries—the dark ages of human progress—after which the era of observation and experiment began, and for the first time men really set themselves to study nature, thus laying the foundation for all the great theoretical advances of our time. As leading to the next great step in theories of evolution, we must note the life-long observations by Tycho Brahe of the apparent motions of the planets; the grand discovery of Kepler that all these apparently erratic motions were due to their revolution round the sun in elliptic orbits, with a fixed relation between their distance from the sun and their periods of revolution; and Newton’s epoch-making theory of universal gravitation by which all these facts and many others since discovered were harmonized and explained."}]}
{"messages": [{"role": "assistant", "content": "As leading to the next great step in theories of evolution, we must note the life-long observations by Tycho Brahe of the apparent motions of the planets; the grand discovery of Kepler that all these apparently erratic motions were due to their revolution round the sun in elliptic orbits, with a fixed relation between their distance from the sun and their periods of revolution; and Newton’s epoch-making theory of universal gravitation by which all these facts and many others since discovered were harmonized and explained. But all this implied no law of development, and it was long thought that the solar system was fixed and unchangeable—that some altogether unknown or miraculous agency must have set it going, and that it had in itself no principle of change or decay, but might continue as it now is to all eternity. It was at the very end of the eighteenth century that Laplace announced his “Nebular Hypothesis,” the first attempt ever made to explain the origin of the solar system under the influence of the known laws of motion, gravitation, and heat, acting upon an altogether different antecedent condition of things—a true process of evolution. Laplace supposed that the whole matter of the solar system was once in a condition of vapor, and that it formed an enormous nebulous mass many times larger than the then known dimensions of the planetary sphere. He showed how, under the influence of gravitation, this nebula would condense, and that such irregularities of motion and density as would be sure to exist would lead to rotation of the mass. Under the law of gravitation this would lead to outer rings being left behind by the contraction of the central mass, which rings would at a later period become drawn together at some point of initial greater density and thus form planets."}]}
{"messages": [{"role": "assistant", "content": "Under the law of gravitation this would lead to outer rings being left behind by the contraction of the central mass, which rings would at a later period become drawn together at some point of initial greater density and thus form planets. The whole process is admitted to be mathematically demonstrable, given the initial conditions; but recent extensions of our knowledge of the interplanetary and interstellar spaces have shown that the supposed void is really full of invisible solid matter, ranging from the bulk of the smaller planets down to the finest dust, and it is very difficult to imagine any possible causes which would keep all the solid matter of the system in a state of vapor, when subject, on the confines of the mass, to the cold of interstellar space. The antecedent condition of our system is now thought to have been either wholly or partially meteoritic, but in either case we have a genuine theory of its evolution which has now been so extended as to include the appearance of comets and meteors, of nebulæ, and star clusters, of temporary, periodic, and colored stars, and many other phenomena of the stellar universe. It is no objection to these grand theories to urge that they do not explain the origin of the matter of the universe, either what it is or how it came to be where we now find it. We can only take one step at a time, and even if in these greater problems any further advance should be as yet denied us, it is still a great thing to have been able to take even one secure step into the vast and mysterious depths of the interstellar spaces. EVOLUTION OF THE EARTH’S CRUST \nAlthough Pythagoras (500 B."}]}
{"messages": [{"role": "assistant", "content": "EVOLUTION OF THE EARTH’S CRUST \nAlthough Pythagoras (500 B. C.) believed that sea and land must often have changed places, and a few other observers at different epochs came to the same conclusion, yet, till quite recent times, the earth was generally supposed to have been always very much as it is now; people spoke of “the eternal hills”; and the great mountain ranges, the mighty ravines and precipices, as well as the deep seas and oceans, were believed to be the direct work of the Creator. It was only in the latter half of the eighteenth century that a few observers began to see the importance of studying the nature of the earth’s crust, so far as it could be reached in ravines, quarries, and mines; and one of the most earnest of these students, Dr. Hutton, of Edinburgh, after more than thirty years of travel and study, published his great work, _The Theory of the Earth_, which must be considered to be the starting-point of modern geology. He maintained that it was only by observing causes now in action that we can explain the phenomena presented by the stratified and igneous rocks; he showed that the former must have been laid down by water, and that the larger part of them, containing as they do marine shells and other fossils, must have been deposited on the sea-bottom. He showed how rain and rivers, frost and snow, wind and heat disintegrated the hardest rocks and would in time excavate the deepest valleys; while earthquakes, however small an elevation any one of them might produce, would in time raise the sea-bottom sufficiently high to form, when denuded, mountain ranges, plains, and valleys like those we now see everywhere upon the earth’s surface."}]}
{"messages": [{"role": "assistant", "content": "He showed how rain and rivers, frost and snow, wind and heat disintegrated the hardest rocks and would in time excavate the deepest valleys; while earthquakes, however small an elevation any one of them might produce, would in time raise the sea-bottom sufficiently high to form, when denuded, mountain ranges, plains, and valleys like those we now see everywhere upon the earth’s surface. He also showed that the most ancient stratified rocks, those that lie at the very base of the series, presented every indication of having been formed in exactly the same way as the most recent ones. Hence he stated a conclusion which excited a storm of opposition, in these words: “In the economy of the world I can find no traces of a beginning, no prospect of an end.” This was thought to imply a denial of creation, and was quite sufficient at that period to prevent the work of any man of science from being judged impartially. But although Playfair and a few others upheld Hutton’s views, they were too novel to receive much support by his contemporaries, and this was especially the case as regards the slow and continuous action of existing causes being sufficient to account for all the known phenomena presented by the crust of the earth. Hence the belief in catastrophes and cataclysms—in great convulsions tearing mountains asunder, and vast floods sweeping over whole continents—continued to prevail, till finally banished by the genius and perseverance of one man, Sir Charles Lyell. His _Principles of Geology_ was first published in 1830, and successive editions, revised and often greatly extended, continued to appear till the author’s death, forty-five years later."}]}
{"messages": [{"role": "assistant", "content": "His _Principles of Geology_ was first published in 1830, and successive editions, revised and often greatly extended, continued to appear till the author’s death, forty-five years later. As this work affords a fine example of the application of the principles of evolution to the later phases of the earth’s history, and as it not only revolutionized scientific opinion in its own domain, but prepared the way for the acceptance of the still more novel and startling application of the same principles to the entire organic world, it will be necessary to show what opinions prevailed at the time it first appeared in order that we may understand how great was the change it effected. In the earlier years of the nineteenth century the standard geological work, both in Great Britain and on the Continent, was Cuvier’s _Essay on the Theory of the Earth_. In 1827 a fifth edition of the English translation appeared, and there was a German translation so late as 1830—sufficient proofs of its wide popularity. Yet this work abounds in statements which are positively ludicrous to any one conversant with modern geology. It never appeals to known causes, but again and again assumes forces to be at work for which no evidence is adduced and which are totally at variance with what we see in the world to-day."}]}
{"messages": [{"role": "assistant", "content": "It never appeals to known causes, but again and again assumes forces to be at work for which no evidence is adduced and which are totally at variance with what we see in the world to-day. A few examples justifying these statements must be here given. Cuvier shows that he was acquainted with the theory of modern causes, but he altogether rejects it, saying that “the march of nature is changed, and none of the agents she now employs would have been sufficient for the production of her ancient works.” He adduces “the primitive mountains” whose “sharp and bristling ridges and peaks are indications of the violent manner in which they have been elevated.” He allows that atmospheric agencies may form sea-cliffs, alluvial deposits, and taluses of loose matter at the foot of the precipices, but he adds: “These are but limited effects to which vegetation in general puts a stop, and which, besides, presuppose the existence of mountains, valleys, and plains—in short, all the inequalities of the globe—and which, therefore, cannot have given rise to those inequalities.” He contrasts the calm and peaceful aspect of the surface of the earth with the appearances discovered when we examine its interior. Here, in the raised beds of shells, the fractured rocks, the inclined or even vertical stratification, he finds abundant proofs “that the surface of the globe has been broken up by revolutions and catastrophes.” \nHe also refers to the numerous large blocks of the primitive rocks scattered over the surface of secondary formations, and separated by deep valleys or even by arms of the sea from the peaks or ridges from which they must have been derived, as further proofs of catastrophes; for, it is argued, they must have been either ejected by volcanic eruptions or carried by waters, which, in either case, “must have exceeded in violence anything we can imagine at the present day,” and he therefore concludes that “it is in vain we search among the powers which now act upon the surface of the earth for causes sufficient to produce the revolutions and catastrophes, the traces of which are exhibited in its crust.” He is quite confident that all these changes go on rapidly, periods of catastrophe alternating with periods of repose. The present surface of the earth he holds to be quite recent, and he maintains “that, if anything in geology be established, it is that the surface of our globe has undergone a great and sudden revolution, the date of which cannot be referred to a much earlier period than five or six thousand years ago; that this revolution overwhelmed and caused to disappear the countries which were previously inhabited by man, and the species of animals now best known; that, on the other hand, it laid dry the bottom of the last sea, and formed of it the countries which are at the present day inhabited.” And he further declares that “this event has been sudden, instantaneous, without any gradation; and what is so clearly demonstrated with respect to this last catastrophe is not less so with reference to those which preceded it.” \nThe method followed by Lyell was the very reverse of that of Cuvier. Instead of assuming hastily that modern causes were totally inadequate, and appealing constantly to purely imaginary and often inconceivable catastrophes, Lyell investigated these causes with painstaking accuracy, applying the tests of survey and time measurement, so as in many cases to prove that, given moderately long periods of time—not a few thousands only, but hundreds of thousands of years—they were fully adequate to explain the phenomena."}]}
{"messages": [{"role": "assistant", "content": "Instead of assuming hastily that modern causes were totally inadequate, and appealing constantly to purely imaginary and often inconceivable catastrophes, Lyell investigated these causes with painstaking accuracy, applying the tests of survey and time measurement, so as in many cases to prove that, given moderately long periods of time—not a few thousands only, but hundreds of thousands of years—they were fully adequate to explain the phenomena. He also showed that the imaginary causes of Cuvier would not explain the facts, for that everywhere in the crust of the earth we found conclusive proofs of very slow continuous changes exactly analogous to what now occur, never of great convulsions, except quite locally, as we have them now. He showed that modern volcanoes had poured out vast masses of melted rock during a single eruption, covering areas as extensive as those which any ancient volcano could be proved to have ejected in an equally short period; that strata were now in process of formation comparable in extent and thickness with any ancient strata; that organic remains are being preserved in them just as in the older rocks; that the land is almost everywhere rising or sinking as of old; that valleys are being excavated and plateaus or mountains upheaved; that earthquake shocks are producing faults beneath the surface; that vegetation is still preparing future coal beds; that limestones, clays, sandstones, metamorphic and igneous rocks are all still being formed; and that, given time, and the intermittent or continuous action of the causes we can now trace in operation, and all the varied features of the earth’s surface, as well as all the contortions and fractures which we discover in its crust, and every other phenomenon supposed to necessitate catastrophes and cataclysms will be again produced. In the massive volumes of the later editions of the _Principles of Geology_ all these points are discussed and illustrated with such a wealth of facts and such cogent yet cautious reasoning as have carried conviction to all modern students. It affords us perhaps the very best proof yet given of evolution in one department of the universe—that of the surface and the crust of the earth we inhabit. Not only have all the chief modifications during an almost unimaginable period of time been clearly depicted, but they have in almost every case been shown to be the inevitable results of real and comparatively well-known causes, such as we now see at work around us."}]}
{"messages": [{"role": "assistant", "content": "Not only have all the chief modifications during an almost unimaginable period of time been clearly depicted, but they have in almost every case been shown to be the inevitable results of real and comparatively well-known causes, such as we now see at work around us. The grand generalizations of Lyell have been strengthened since his death by more complete investigations of certain phenomena and their causes than were possible in his day; while the only objections to them seem to be founded, to some extent, upon a misconception. He has been termed a “Uniformitarian,” and it is alleged that it is unphilosophical to take the limited range of causes we now see in action, as a measure of those which have acted during all past geological time. But neither Lyell nor his followers make any such assumption. They merely say, we do not find any proof of greater or more violent causes in action in past times, and we do find many indications that the great natural forces then in action—seas and rivers, sun and cloud, rain and hail, frost and snow, as well as the very texture and constituents of the older rocks, and the mode in which the organisms of each age are preserved in them, must have been in their general nature and magnitude very much as they are now. Other objections, such as that the internal forces were greater when the earth was hotter, and that tidal effects must have been more powerful when the moon was nearer the earth, are altogether beside the question until we can obtain more definite measures of past time than we now possess in reference to both geological and cosmical phenomena."}]}
{"messages": [{"role": "assistant", "content": "Other objections, such as that the internal forces were greater when the earth was hotter, and that tidal effects must have been more powerful when the moon was nearer the earth, are altogether beside the question until we can obtain more definite measures of past time than we now possess in reference to both geological and cosmical phenomena. It may well be that the physical changes above referred to have been so slow that they would have produced no perceptibly increased effect at the epoch of the early stratified rocks. Lyell’s doctrine is simply that of real against imaginary causes, and he only denies catastrophes and more violent agencies in early times, because there is no clear evidence of their actual existence, and also because known causes are quite competent to explain all geological phenomena. It must be remembered, too, that uniformitarians have never limited the natural forces of past geological periods to the precise limits of which we have had experience during the historical period. What they maintain is, that forces of the same _nature_ and of the same _order of magnitude_ are adequate to have brought about the evolution of the crust of the earth as we now find it. ORGANIC EVOLUTION, ITS LAWS AND CAUSES \nWe now come to that branch of the subject which is the most important and distinctive of our age, and which, in popular estimation, alone constitutes evolution—the mode of origin of the innumerable species of animal and plant life which now exist or have ever existed upon the earth."}]}
{"messages": [{"role": "assistant", "content": "ORGANIC EVOLUTION, ITS LAWS AND CAUSES \nWe now come to that branch of the subject which is the most important and distinctive of our age, and which, in popular estimation, alone constitutes evolution—the mode of origin of the innumerable species of animal and plant life which now exist or have ever existed upon the earth. The origin of the different forms of life has till quite recent times been looked upon as an almost insoluble problem, although a few advanced thinkers, even in the eighteenth century, perceived that it was probably the result of some natural process of modification or evolution; but no force or law had been set forth and established in any way adequate to produce it until the publication of Darwin’s _Origin of Species_, in 1859. In the later editions of that work, Darwin has given a historical sketch of the progress of opinion on the subject. I shall, therefore, now only notice a few great writers which he has not referred to. We have seen what an impossible and even ludicrous explanation had to be given by Lucretius; and from his day down to the middle of the eighteenth century no advance had been made. Either the problem was not referred to at all, or the theological doctrine of a special creation was held to be the only possible one."}]}
{"messages": [{"role": "assistant", "content": "Either the problem was not referred to at all, or the theological doctrine of a special creation was held to be the only possible one. But in the middle of the eighteenth century the great French naturalist, Buffon, published his very important work, _Histoire Naturelle_, in fifteen volumes (1749–1767), in which, besides describing the characters and habits of all the animals then known, he introduced much philosophical and speculative thought, which would probably have been carried much further had he not felt obliged to conform to the religious prejudices of the age. We are indebted to Mr. Samuel Butler for having brought together all the important passages of Buffon’s voluminous and now little-read works bearing upon the question of evolution, and it is from his volume that I quote. Buffon lays stress on the great resemblance of all mammalia in internal structure, showing that the most unlike creatures may be really alike structurally. He says: “The horse, for example—what can at first sight seem more unlike mankind?"}]}
{"messages": [{"role": "assistant", "content": "He says: “The horse, for example—what can at first sight seem more unlike mankind? Yet when we compare man and horse, point by point and detail by detail, our wonder is excited rather by the resemblances than by the differences between them.” He then shows that all the parts of the skeleton agree, and that it is only in proportions, the increase of some bones and the suppression of others, that they differ, adding: “If we regard the matter thus, not only the ass and the horse, but even man himself, the apes, etc., might be regarded as forming members of one and the same family.” Then, after a few more illustrations, he remarks: “If we once admit that there are families of plants and animals, so that the ass may be of the family of the horse, and that the one may only differ from the other by degeneration from a common ancestor, we might be driven to admit that the ape is of the family of man, that he is but a degenerate man, and that he and man have had a common ancestor.... If it were once shown that we had right grounds for establishing these families, if the point were once gained that among plants and animals there have been even a single species which had been produced in the course of direct descent from another species, then there is no further limit to be set to the power of nature, and we should not be wrong in supposing that with sufficient time she could have evolved all other organized forms from one primordial type.” \nThis indicates clearly enough his own opinion, but to save himself from the ecclesiastical authorities he at once adds this saving clause: “But no! It is certain, from revelation, that all animals have alike been favored with the grace of an act of direct creation, and that the first pair of every species issued full formed from the hands of the Creator.” \nSuch examples of disarming religious prejudice are frequent, but he continually recurs to statements as to mutability which neutralize them. Here, for example, is a broad claim for nature as opposed to creation. He has been showing how variable are many animals, and how changes of food, climate, and general surroundings influence both their forms and their habits; and then he exclaims: \n“What cannot nature effect with such means at her disposal?"}]}
{"messages": [{"role": "assistant", "content": "He has been showing how variable are many animals, and how changes of food, climate, and general surroundings influence both their forms and their habits; and then he exclaims: \n“What cannot nature effect with such means at her disposal? She can do all except either create matter or destroy it. These two extremes of power the Deity has reserved for Himself only; creation and destruction are the action of His omnipotence. To alter and undo, to develop and renew—these are powers which He has handed over to the charge of nature.” \nHere we have a claim for the power of nature in the modification of species which fully comes up to the requirements of the most advanced evolutionist. It is remarkable, too, how clearly he perceived the great factors so important for the evolution of organisms, rapid multiplication, great variability, and the struggle for existence. Thus he remarks: “It may be said that the movement of nature turns upon two immovable pivots—one, the illimitable fecundity which she has given to all species; the other, the innumerable difficulties which reduce the results of that fecundity and leave throughout time nearly the same quantity of individuals in every species.” Here the term “difficulties” corresponds to the “positive checks” of Malthus, and to the “struggle for existence” of Darwin; and he again and again refers to variability—as when he says: “Hence, when by some chance, common enough with nature, a variation or special feature makes its appearance, man has tried to perpetuate it by uniting together the individuals in which it has appeared.” \nAs Buffon thus clearly understood artificial selection, thoroughly appreciated the rapid increase of all organisms, and equally well saw that their inordinate increase was wholly neutralized through such destructive agencies as hunger, disease, and enemies, and as, at the same time, he had such unbounded faith in the power of nature to modify animal and vegetable forms, we feel assured that this great writer and original thinker only needed freedom to pursue this train of thought a little further and he would certainly have anticipated Darwin’s great discovery of natural selection by a whole century."}]}
{"messages": [{"role": "assistant", "content": "Thus he remarks: “It may be said that the movement of nature turns upon two immovable pivots—one, the illimitable fecundity which she has given to all species; the other, the innumerable difficulties which reduce the results of that fecundity and leave throughout time nearly the same quantity of individuals in every species.” Here the term “difficulties” corresponds to the “positive checks” of Malthus, and to the “struggle for existence” of Darwin; and he again and again refers to variability—as when he says: “Hence, when by some chance, common enough with nature, a variation or special feature makes its appearance, man has tried to perpetuate it by uniting together the individuals in which it has appeared.” \nAs Buffon thus clearly understood artificial selection, thoroughly appreciated the rapid increase of all organisms, and equally well saw that their inordinate increase was wholly neutralized through such destructive agencies as hunger, disease, and enemies, and as, at the same time, he had such unbounded faith in the power of nature to modify animal and vegetable forms, we feel assured that this great writer and original thinker only needed freedom to pursue this train of thought a little further and he would certainly have anticipated Darwin’s great discovery of natural selection by a whole century. Even as it is we must class him as one of the great pioneers of organic evolution. The next distinct step towards a theory of organic evolution was made by the poet Goethe at the very end of the eighteenth century, in his views of the metamorphosis of plants. He pointed out the successive modifications of the leaf which produced all the other essential parts of the higher plants—the simple cotyledons or seed leaves became modified into the variously formed leaves of the fully grown plants; these again were successively modified into the calyx, corolla, stamens, and ovary of the flower. He supposed this to be due to the increased refinement of the sap under the influence of light and air, and to indicate the steps by which the various parts of the flower had been developed. It was, therefore, a theory of evolution; but it was very unsatisfactory, inasmuch as it in no way accounted for the wonderful variety of the floral organs, or indicated any purpose served by the most prominent and conspicuous part of the flower, the highly colored and often strangely formed corolla."}]}
{"messages": [{"role": "assistant", "content": "It was, therefore, a theory of evolution; but it was very unsatisfactory, inasmuch as it in no way accounted for the wonderful variety of the floral organs, or indicated any purpose served by the most prominent and conspicuous part of the flower, the highly colored and often strangely formed corolla. It was also erroneous in supposing that the corolla was a modified calyx, whereas it is now known to be a modification of the stamens. Next came the great work of Lamarck in the first decade of the nineteenth century, in which he proposed a general system of evolution of the whole animal world. Hence he may be termed the first systematic evolutionist. His system has been rather fully described by Lyell, who, in his _Principles of Geology_, devotes a whole chapter to a summary of his doctrines; while Mr. Butler gives copious quotations in three chapters of his _Evolution Old and New_; and any one who is not acquainted with the original work of Lamarck should read these two authors in order to understand how wide was his knowledge, how ingenious his explanations, and in how many important points he anticipated the views both of Lyell and Darwin."}]}
{"messages": [{"role": "assistant", "content": "Butler gives copious quotations in three chapters of his _Evolution Old and New_; and any one who is not acquainted with the original work of Lamarck should read these two authors in order to understand how wide was his knowledge, how ingenious his explanations, and in how many important points he anticipated the views both of Lyell and Darwin. But he was half a century in advance of his age, and his only alleged causes of modification—changed conditions, use and disuse, habit and effort—were wholly insufficient to account for the vast range of the phenomena presented by the innumerable minute adaptations of living organisms to their conditions of life. He even imputed all the modifications of domestic animals to the changed conditions of food and habits to which they have been subjected by man, making no reference to the use of selection by breeders, in this respect falling short of his great predecessor, Buffon. The general laws which Lamarck deduces from his elaborate study of nature are these: \n“Firstly. That in every animal which has not passed its limit of development, the more frequent and sustained employment of any organ develops and aggrandizes it, giving it a power proportionate to the duration of its employment, while the same organ, in default of constant use, becomes insensibly weakened and deteriorated, decreasing imperceptibly in power until it finally disappears. “Secondly."}]}
{"messages": [{"role": "assistant", "content": "“Secondly. That these gains or losses of organic development, due to use or disuse, are transmitted to offspring, provided they have been common to both sexes, or to the animals from which the offspring have descended.” \nThe whole force of this argument depends upon the second clause—the inheritance of those individual modifications due to use and disuse. But no direct evidence of this has ever been found, while there is a good deal of evidence showing that it does not occur. Again, there are many structures which cannot have been produced by use, such, for example, as the feathers of the peacock’s train, the poison in the serpent’s fangs, the hard shells of nuts, the prickly covering of many fruits, the varied armor of the turtle, porcupine, crocodile, and many others. For these reasons Lamarck’s views gained few converts; and although some of his arguments have been upheld in recent years, the fatal objections to his general principle as a means of explaining the evolution of organic forms has never been overcome. Between the periods of Lamarck and Darwin many advances were made which clearly pointed to a general law of evolution in nature."}]}
{"messages": [{"role": "assistant", "content": "Between the periods of Lamarck and Darwin many advances were made which clearly pointed to a general law of evolution in nature. Such were Sir William Grove’s lectures on the “Correlation of the Physical Forces,” in 1842; Helmholtz on the “Conservation of Energy,” in 1847; and Herbert Spencer’s essay on “The Development Hypothesis,” in 1852. This latter work was a complete and almost unanswerable argument for a natural process of continuous evolution of the whole visible universe, including organic nature, man, and social phenomena. It is further extended in the later editions of the author’s _First Principles_, which, as a coherent exposition of philosophy, co-ordinating and explaining all human knowledge of the universe into one great system of evolution everywhere conforming to the same general principles, must be held to be one of the greatest intellectual achievements of the nineteenth century. It left, however, the exact method of evolution of organisms untouched, and thus failed to account for those complex adaptations and appearances of design in the various species of animals and plants which have always been the stronghold of those who advocated special creation. This difficulty was met by Darwin’s theory of _The Origin of Species by Means of Natural Selection_, published in 1859, and the series of works that succeeded it; and to a brief sketch of this theory the remainder of our space must be devoted."}]}
{"messages": [{"role": "assistant", "content": "This difficulty was met by Darwin’s theory of _The Origin of Species by Means of Natural Selection_, published in 1859, and the series of works that succeeded it; and to a brief sketch of this theory the remainder of our space must be devoted. THE THEORY OF “NATURAL SELECTION” \nAlthough, as we have seen, a succession of great writers and thinkers had for more than half a century shown the necessity for some process of evolution as the only rational or intelligible mode of origin of existing species of animals and plants, as well as of the whole physical universe, yet these views were by no means generally accepted by the educated classes, while few bodies of students were less influenced by them than zoologists and botanists, generally known as naturalists. Now, Darwin wrote especially for these classes, and no one knew better than he did their great prejudice on this matter. Not only had such men as Sir Charles Lyell and Sir John Herschel expressed themselves strongly against all theories of the transmutation of species, but the universal contempt and indignation of naturalists as well as theologians against _The Vestiges of Creation_, published anonymously a few years earlier, and giving a most temperate and even religious exposition of the general arguments for the universality of evolution, showed what any one might expect who advocated and attempted to demonstrate a similar theory. This accounts for Darwin writing to Sir Joseph Hooker, in 1844, of his being “almost convinced that species are not (it is like confessing a murder) immutable,” and again, in 1845, to the Rev. L."}]}
{"messages": [{"role": "assistant", "content": "L. Blomefield, that he now saw the way in which new varieties become exquisitely adapted to the external conditions of life and to other surrounding beings, and he adds: “I am a bold man to lay myself open to being thought a complete fool, and a most deliberate one.” It is only by a consideration of the frame of mind of even advanced thinkers at the time Darwin was preparing his work, and remembering how small was the effect which had been produced by Buffon, Goethe, Lamarck, the author of _Vestiges of Creation_, and the earlier writings of Herbert Spencer, that we can adequately realize the marvellous work that he accomplished. Let us now briefly consider the essential nature of this new theory, which in a few brief years became the established belief of the great majority of the students of nature, and which also gave a new interest in nature to the whole thinking world. The theory of natural selection is founded upon a few groups of thoroughly ascertained and universally admitted facts, with the direct and necessary results of those facts. The first group of facts consists of the great powers of increase of all organisms and the circumstance that, notwithstanding this great yearly increase, the actual population of each species remains stationary, there being no permanent increase. Now, these two facts were recognized by Buffon, but though, of course, known to all subsequent writers, were fully appreciated or thought out to their logical results by none of them."}]}
{"messages": [{"role": "assistant", "content": "Now, these two facts were recognized by Buffon, but though, of course, known to all subsequent writers, were fully appreciated or thought out to their logical results by none of them. Lamarck, so far as I can ascertain, took no notice of them whatever. Darwin has given illustrations of these facts in Chapter IV. of the _Origin of Species_, and I have added others in the second chapter of my _Darwinism_. That the population of each species remains stationary, with, of course, considerable fluctuations, is both a matter of observation and of reasoning. The powers of increase of all creatures are so great that if there is in any country room and food for a larger number of any species they will be produced in a year or two."}]}
{"messages": [{"role": "assistant", "content": "The powers of increase of all creatures are so great that if there is in any country room and food for a larger number of any species they will be produced in a year or two. It is impossible, therefore, to believe that, in a state of nature, where all kinds of animals and plants have lived together as they best could for thousands of years, there can be any important difference in their numbers from year to year or from century to century. Now, it is as a consequence of these two indisputable facts that the struggle for existence necessarily results. For if every year each pair of animals or each plant produces only ten young animals or plants, and this is very far below the average, and if the adult life of these is taken at ten years, again below the average of the higher plants and animals, then, unless some of the parents die, the whole of the offspring must die off every year; or, in other words, only as many young can survive as are necessary to replace the old ones that die. Hence the deaths must always (on the average and in the long run) equal the births. This terrible yearly destruction is an absolutely certain fact, as well as an inevitable result of the two preceding facts, and it is said to be due to the struggle for existence."}]}
{"messages": [{"role": "assistant", "content": "This terrible yearly destruction is an absolutely certain fact, as well as an inevitable result of the two preceding facts, and it is said to be due to the struggle for existence. This struggle is manifold in its nature. Individuals of the same species struggle together for food, for light, for moisture; they struggle also against other species having the same wants; they struggle against every kind of enemy, from parasitic worms and insects up to carnivorous animals; and there is a continual struggle with the forces of nature—frosts, rains, droughts, floods, and tempests. These varied causes of destruction may be seen constantly at work by any one who looks for them. They act from the moment of birth, being more especially destructive to the young; and, as only one in ten or fifty or a thousand (according to the rate of increase of the particular species) can possibly come to the full breeding age, we feel compelled to ask ourselves: What determines the nine or the forty-nine or the nine hundred and ninety-nine, as the case may be, which die, and the one which survives? Darwin calls this process of extermination one of “natural selection”—that is, by this process nature weeds out the weak, the unhealthy, the unadapted, the imperfect in any way."}]}
{"messages": [{"role": "assistant", "content": "Darwin calls this process of extermination one of “natural selection”—that is, by this process nature weeds out the weak, the unhealthy, the unadapted, the imperfect in any way. Of course, what may be called chance or accident produces many deaths of individuals otherwise well fitted to live, but if we think of the process going on day by day and year by year till only one in a hundred of those born in a given area are left alive, it is impossible to suppose that the _one_ which has passed through all the dangers and risks which have been fatal to, say, his ninety-nine relations was not, in all the faculties and qualities essential to the continuance of the race, decidedly better organized than the bulk of those which succumbed. Herbert Spencer calls the process the “survival of the fittest,” and though the term may not be strictly accurate in the case of any one species in any one year, yet when we consider that the struggle is going on _every_ year, during the whole duration of each species, we cannot doubt that, on the whole, and in the long run, those which survive are among the fittest. The struggle is so severe, so incessant, that the smallest defect in any sense organ, any physical weakness, any imperfection in constitution, will almost certainly, at one time or another, be fatal. This continual weeding out of the less fit, in every generation, and with exceptional severity in recurring adverse seasons, will produce two distinct effects, which require to be clearly distinguished. The first is the preservation of each species in the highest state of adaptation to the conditions of its existence; and, therefore, so long as these conditions remained unchanged, the effect of natural selection is to keep each well-adapted species also unchanged."}]}
{"messages": [{"role": "assistant", "content": "The first is the preservation of each species in the highest state of adaptation to the conditions of its existence; and, therefore, so long as these conditions remained unchanged, the effect of natural selection is to keep each well-adapted species also unchanged. The second effect is produced whenever the conditions vary, when, taking advantage of the variations continually occurring in all well-adapted and therefore populous species, the same process will slowly but surely bring about complete adaptation to the new conditions. And here another fact—the normal variability of all populous or dominant species, which is seldom realized except by those who have largely and minutely compared the individuals of many species in a state of nature—comes into play. There are some writers who admit all the preceding facts and reasoning, so far as the action of natural selection in weeding out the unfit and thus keeping every species in the highest state of efficiency is concerned, but who deny that it can modify them in such a way as to adapt them to new conditions, because they allege that “the right variations will not always occur at the right time.” This seems a strong and real objection to many of their readers, but to those who have studied the variability of species in nature, it is a mere verbal difficulty dependent on ignorance of the actual facts. A brief statement of the facts must therefore be given. Of late years, and chiefly since Darwin’s works were written, the variability of animals and plants in a state of nature has been carefully studied, by actual comparison and measurement of scores, hundreds, and even thousands of individuals of many common, that is, abundant and widely distributed species; and it is found that in almost every case they vary greatly, and, what is still more important, that every organ and every appendage varies independently and to a large amount."}]}
{"messages": [{"role": "assistant", "content": "Of late years, and chiefly since Darwin’s works were written, the variability of animals and plants in a state of nature has been carefully studied, by actual comparison and measurement of scores, hundreds, and even thousands of individuals of many common, that is, abundant and widely distributed species; and it is found that in almost every case they vary greatly, and, what is still more important, that every organ and every appendage varies independently and to a large amount. Some of the best known of these facts of variation are adduced in my _Darwinism_, and are illustrated by numerous diagrams, and much more extensive series have since been examined, always with the same general result. By large variability is meant a variation of from ten to twenty-five per cent. on each side of the mean size, this amount of variation occurring in at least five or ten per cent. of the whole number of individuals, and in every organ or part as yet examined, external or internal. Now, as the weeding-out process is so severe, only from one in ten to one in a hundred of those born surviving to produce young, the above proportion of variations affords ample scope for the selection of any variation needed in order to modify the species so as to bring it into harmony with new or changing conditions."}]}
{"messages": [{"role": "assistant", "content": "Now, as the weeding-out process is so severe, only from one in ten to one in a hundred of those born surviving to produce young, the above proportion of variations affords ample scope for the selection of any variation needed in order to modify the species so as to bring it into harmony with new or changing conditions. And this will be the more easy and certain if we consider how slowly land-surfaces and climates undergo permanent changes; and these are certainly the kind of changes that initiate and compel alterations, first, perhaps, in the distribution, and afterwards in the structure and habits of species. It follows, therefore, as an absolutely necessary conclusion from the facts, if natural selection can and does keep each continually varying species in close adaptation to an unchanging environment, that it preserves the fixity of its mean or average condition, and almost every objector admits this. Then, given a slowly changing environment, the same power must inevitably bring about whatever corresponding change is needed for the well-being and permanent survival of the various species which are subjected to those changed conditions. I shall not add here a further consideration of the objections and difficulties alleged by critics of the theory. All of these have, I believe, been fully answered either by Darwin or myself, many of the most recent having been discussed in review articles."}]}
{"messages": [{"role": "assistant", "content": "All of these have, I believe, been fully answered either by Darwin or myself, many of the most recent having been discussed in review articles. Suffice it to say here that this theory of natural selection—meaning the elimination of the least fit, and therefore the ultimate “survival of the fittest”—has furnished a rational and precise explanation of the means of adaptation of all existing organisms to their conditions, and therefore of their transformation from the series of distinct but allied species which occupied the earth at some preceding epoch. In this sense it has actually demonstrated the “origin of species,” and, by carrying back this process step by step into earlier and earlier geological times, we are able mentally to follow out the evolution of all forms of life from one or a few primordial forms. Natural selection has thus supplied that motive power of change and adaptation that was wanting in all earlier attempts at explanation, and this has led to its very general acceptance both by naturalists and by the great majority of thinkers and men of science. The brief sketch now given of the progress of human thought on the questions of the fact and the mode of the evolution of the material universe indicates how great has been the progress during the nineteenth as compared with all preceding centuries. Although the philosophical writers of classical times obtained a few glimpses of the action of law in nature regulating its successive changes, nothing satisfactory could be effected till the actual facts had been better ascertained by the whole body of workers who, during the last five centuries, have penetrated ever more and more deeply into nature’s mysteries and laws."}]}
{"messages": [{"role": "assistant", "content": "Although the philosophical writers of classical times obtained a few glimpses of the action of law in nature regulating its successive changes, nothing satisfactory could be effected till the actual facts had been better ascertained by the whole body of workers who, during the last five centuries, have penetrated ever more and more deeply into nature’s mysteries and laws. By their labors we became possessed of such a body of carefully observed facts that, towards the end of the eighteenth century, such thinkers as Laplace and Hutton were enabled to give us the first rudiments of theories of evolution as applied to the solar system and the earth’s crust, both of which have been greatly developed and rendered more secure during the century just passed away. In like manner Buffon and Goethe may be said to have started the idea of organic evolution, more systematically treated a little later by Lamarck, but still without any discovery of laws adequate to produce the results we see everywhere in nature. The subject then languished, till, after twenty years of observation and research, Charles Darwin produced a work which at once satisfied many thinkers that the long-desired clew had been discovered. Its acceptance by almost the whole scientific world soon followed: it threw new light on almost every branch of research, and it will probably take its place, in the opinion of future generations, as the crowning achievement of the nineteenth century. ALFRED RUSSEL WALLACE."}]}
{"messages": [{"role": "assistant", "content": "ALFRED RUSSEL WALLACE. CHEMISTRY \n\nThe progress of the science of chemistry forms one phase of the progress of human thought. While at first mankind was contented to observe certain phenomena, and to utilize them for industrial purposes, if they were found suitable, “philosophers,” as the thinking portion of our race loved to call themselves, have always attempted to assign some explanation for observed facts, and to group them into similars and dissimilars. It was for long imagined, following the doctrines of the Greeks and of their predecessors, that all matter consisted of four elements or principles, names which survive to this day in popular language. These were “fire,” “air,” “water,” and “earth.” It was not until the seventeenth century that Boyle in his _Sceptical Chymist_ (1661) laid the foundations of the modern science, by pointing out that it was impossible to explain the existence of the fairly numerous chemical substances known in his day, or the changes which they can be made to undergo, by means of the ancient Greek hypotheses regarding the constitution of matter. He laid down the definition of the modern meaning of the word “element”; he declined to accept the current view that the properties of matter could be modified by its assimilating the qualities of fire, air, earth, or water, and he defined an element as the _constituent_ of a compound body."}]}
{"messages": [{"role": "assistant", "content": "He laid down the definition of the modern meaning of the word “element”; he declined to accept the current view that the properties of matter could be modified by its assimilating the qualities of fire, air, earth, or water, and he defined an element as the _constituent_ of a compound body. The first problem, then, to be solved, was to determine which of the numerous forms of matter were to be regarded as elementary, and which are compound, or composed of two or more elements in a state of combination; and to produce such compounds by causing the appropriate elements to unite with each other. One of the first objects to excite curiosity and interest was the air which surrounds us, and in which we live and move and have our being. It was, however, endowed with a semi-spiritual and scarcely corporeal nature in the ideas of our ancestors, for it does not affect the senses of sight, smell, or taste, and though it can be felt, yet it eludes our grasp. The word “gas,” moreover, was not invented until Van Helmont devised it to designate various kinds of “airs” which he had observed. The important part which gases play in the constitution of many chemical compounds was accordingly overlooked; and, indeed, it appeared to be almost as striking a feat of necromancy to produce a quantity of a gas of great volume from a small pinch of solid powder as for a “Jinn” of enormous stature but of delicate texture to issue from a brass pot, as related in the _Arabian Nights Entertainments_."}]}
{"messages": [{"role": "assistant", "content": "The important part which gases play in the constitution of many chemical compounds was accordingly overlooked; and, indeed, it appeared to be almost as striking a feat of necromancy to produce a quantity of a gas of great volume from a small pinch of solid powder as for a “Jinn” of enormous stature but of delicate texture to issue from a brass pot, as related in the _Arabian Nights Entertainments_. Gradually, however, it came to be recognized, not merely that gases have corporeal existence, but that they even possess weight. This, though foreshadowed by Torricelli, Jean Rey, and others, was first clearly proved by Black, professor of chemistry in Edinburgh, in 1752, through his masterly researches, as carbonic acid. The ignorance of the material nature of gases and of their weight lies at the bottom of the “Phlogistic Theory,” a theory devised by Stahl about the year 1690, to account for the phenomena of combustion and respiration and the recovery or “reduction” of metals from their “earths” by heating with charcoal or allied bodies. According to this inverted theory, a substance capable of burning was imagined to contain more or less phlogiston, a principle which it parted with on burning, leaving an earth deprived of phlogiston, or “dephlogisticated,” behind if a metal. This earth, when heated with substances rich in phlogiston, such as coal, wood, flour, and similar bodies, recovered the phlogiston, which it had lost on burning, and, with the added phlogiston, its metallic character."}]}
{"messages": [{"role": "assistant", "content": "This earth, when heated with substances rich in phlogiston, such as coal, wood, flour, and similar bodies, recovered the phlogiston, which it had lost on burning, and, with the added phlogiston, its metallic character. Other substances, such as phosphorus and sulphur, gave solids or acid liquids, to which phlogiston was not so easy to add; but even they could be rephlogisticated. On this hypothesis, it was the earths, and such acid liquids as sulphuric or phosphoric acids, which were the elements; the metals and sulphur and phosphorus were their compounds with phlogiston. The discovery of oxygen by Priestley and by Scheele in 1774, and the explanation of its functions by Lavoisier during the following ten years, gave their true meaning to these phenomena. It was then recognized that combustion was union with oxygen; that an “earth” or “calx” was to be regarded as the compound of a metal with oxygen; that when a metal becomes tarnished, and converted into such an earthy powder, it is being oxidized; that this oxide, on ignition with charcoal or carbon, or with compounds such as coal, flour, or wood, of which carbon is a constituent, gives up its oxygen to the carbon, forming an oxide of carbon, carbonic oxide on the one hand, or carbonic “acid” on the other, while the metal is reproduced in its “reguline” or metallic condition, and that the true elements are metals, carbon, sulphur, phosphorus, and similar bodies, and not the products of their oxidation. The discovery that air is in the main a mixture of nitrogen, an inert gas, and oxygen, an active one, together with a small proportion of carbonic “acid” (or, as it is now termed, anhydride)—a discovery perfected by Rutherford, Black, and Cavendish—and that water is a compound with oxygen of hydrogen, previously known as inflammable air, by Cavendish and by Watt, finally overthrew the theory of phlogiston; but at the beginning of this century it still lingered on, and was defended by Priestley until his death in 1804."}]}
{"messages": [{"role": "assistant", "content": "The discovery that air is in the main a mixture of nitrogen, an inert gas, and oxygen, an active one, together with a small proportion of carbonic “acid” (or, as it is now termed, anhydride)—a discovery perfected by Rutherford, Black, and Cavendish—and that water is a compound with oxygen of hydrogen, previously known as inflammable air, by Cavendish and by Watt, finally overthrew the theory of phlogiston; but at the beginning of this century it still lingered on, and was defended by Priestley until his death in 1804. Such, in brief, was the condition of chemical thought in the year 1800. Scheele had died in 1786, at the early age of forty-four; Lavoisier was one of the victims of the French Revolution, having been guillotined in 1794; Cavendish had ceased to work at chemical problems, and was devoting his extraordinary abilities to physical problems of the highest importance, while living the life of an eccentric recluse, and Priestley, driven by religious persecution from England to the more tolerant shores of America, was enjoying a peaceful old age, enlivened by occasional incursions into the region of sectarian controversy. The first striking discovery of our century was that of the compound nature of the alkalies and of the alkaline earths. This discovery was made by Humphry Davy. Born in Cornwall in 1778, he began the study of chemistry, self-taught, in 1796; and in 1799 he became director of the “Pneumatic Institution,” an undertaking founded by Dr."}]}
{"messages": [{"role": "assistant", "content": "Born in Cornwall in 1778, he began the study of chemistry, self-taught, in 1796; and in 1799 he became director of the “Pneumatic Institution,” an undertaking founded by Dr. Beddoes, at Bristol, for the purpose of experiments on the curative effects of gases in general. Here he at once made his mark by the discovery of the remarkable properties of “laughing gas,” or nitrous oxide. At the same time he constructed a galvanic battery, and began to perform experiments with it in attempting to decompose chemical compounds by its means. In 1801 Davy was appointed professor of chemistry at the Royal Institution, a society or club which had been founded a few years previously by Benjamin Thompson, Count Rumford, for the purpose of instructing and amusing its members with recent discoveries in chemistry and natural philosophy. In 1807 Davy applied his galvanic battery to the decomposition of damp caustic potash and soda, using platinum poles."}]}
{"messages": [{"role": "assistant", "content": "In 1807 Davy applied his galvanic battery to the decomposition of damp caustic potash and soda, using platinum poles. He was rewarded by seeing globules of metal, resembling mercury in appearance, at the negative pole; and he subsequently proved that these globules, when burned, reproduced the alkali from which they had been derived. They also combined with “oxymuriatic acid,” as chlorine (discovered by Scheele) was then termed, forming ordinary salt, if sodium be employed, and the analogous salt, “muriate of potash,” if the allied metal, potassium, were subjected to combustion. By using mercury as the negative pole, and passing a current through a strong solution of the chloride of calcium, strontium, or barium, Davy succeeded in procuring mixtures with mercury or “amalgams” of their metals, to which he gave the names calcium, strontium, and barium. Distillation removed most of the mercury, and the metal was left behind in a state of comparative purity. The alkali metals, potassium and sodium, were found to attack glass, liberating “the basis of the silex,” to which the name silicon has since been given."}]}
{"messages": [{"role": "assistant", "content": "The alkali metals, potassium and sodium, were found to attack glass, liberating “the basis of the silex,” to which the name silicon has since been given. Thus nearly the last of the “earths” had been decomposed. It was proved that not merely were the “calces” of iron, copper, lead, and other well-known metals compounds of the respective metals with oxygen, but Davy showed that lime, and its allies, strontia and baryta, and even silica or flint, were to be regarded as oxides of elements of metallic appearance. To complete our review of this part of the subject, suffice it to say that aluminum, a metal now produced on an industrial scale, was prepared for the first time in 1827 by Wöhler, professor of chemistry at Göttingen, by the action of potassium on its chloride, and alumina, the earthy basis of clay, was shown to be the oxide of the metal aluminum. Indeed, the preparation of this metal in quantity is now carried out at Schoffhausen-on-the-Rhine and at the Falls of Foyers, in Scotland, by electrolysis of the oxide dissolved in melted cryolite, a mineral consisting of the fluorides of sodium and aluminum, by a method differing only in scale from that by means of which Davy isolated sodium and potassium in 1806. To Davy, too, belongs the merit of having dethroned oxygen from its central position among the elements."}]}
{"messages": [{"role": "assistant", "content": "To Davy, too, belongs the merit of having dethroned oxygen from its central position among the elements. Lavoisier gave to this important gas the name “oxygen,” because he imagined it to be the constituent of all acids. He renamed the common compounds of oxygen in such a manner that the term oxygen was not even represented in the name—only inferred. Thus a “nitrate” is a compound of an oxide of nitrogen and an oxide of a metal; a “sulphate,” of the oxide of a metal with one of the oxides of sulphur, and so on. Davy, by discovering the elementary nature of chlorine, showed, first, that it is not an oxide of hydrochloric acid (or muriatic acid as it was then called); and, second, that the latter acid is the compound of the element chlorine with hydrogen. This he did by passing chlorine over white-hot carbon—a substance eminently suited to deprive oxy-compounds of their oxygen—and proving that no oxide of carbon is thereby produced; by acting on certain chlorides, such as those of tin or phosphorus with ammonia, and showing that no oxide of tin or phosphorus is formed; and, lastly, by decomposing “muriatic acid gas” (gaseous hydrogen chloride) with sodium, and showing that the only product besides common salt is hydrogen."}]}
{"messages": [{"role": "assistant", "content": "This he did by passing chlorine over white-hot carbon—a substance eminently suited to deprive oxy-compounds of their oxygen—and proving that no oxide of carbon is thereby produced; by acting on certain chlorides, such as those of tin or phosphorus with ammonia, and showing that no oxide of tin or phosphorus is formed; and, lastly, by decomposing “muriatic acid gas” (gaseous hydrogen chloride) with sodium, and showing that the only product besides common salt is hydrogen. Instead, therefore, of the former theory that a chloride was a compound of the unknown basis of oxymuriatic acid with oxygen and the oxide of a metal, he introduced the simpler and correct view that a chloride is merely a compound of the element chlorine with a metal. In 1813 he established the similar nature of fluorine, pointing out that on the analogy of the chlorides it was a fair deduction that the fluorides are compounds of an undiscovered element, fluorine, with metals; and that hydrofluoric acid is the true analogue of hydrochloric acid. The truth of this forecast has been established of recent years by Henri Moissan, who isolated gaseous fluorine by subjecting a mixture of hydrofluoric acid and hydrogen potassium fluoride contained in a platinum U tube to the action of a powerful electric current. He has recently found that the tube may be equally well constructed of copper; and this may soon lead to the industrial application of the process. The difficulty of isolating fluorine is due to its extraordinary chemical energy; for there are few substances, elementary or compound, which resist the action of this pale yellow, suffocating gas."}]}
{"messages": [{"role": "assistant", "content": "The difficulty of isolating fluorine is due to its extraordinary chemical energy; for there are few substances, elementary or compound, which resist the action of this pale yellow, suffocating gas. In 1811 iodine, separated by Courtois from the ashes of sea-plants, was shown by Davy to be an element analogous to chlorine. Gay-Lussac subsequently investigated it and prepared many of its compounds; and in 1826 the last of these elements, bromine, was discovered in the mother-liquor of sea-salt by Balard. The elements of this group have been termed “halogens,” or “salt producers.” \nWhile Davy was pouring his researches into the astonished ears of the scientific and dilettante world, John Dalton, a Manchester school-master, conceived a theory that has proved of the utmost service to the science of chemistry, and which bids fair to outlast our day. It had been noticed by Wenzel, by Richter, by Wollaston, and by Cavendish, towards the end of the last century, that the same compounds contain the same constituents in the same proportions, or, as the phrase runs, “possess constant composition.” Wollaston, indeed, had gone one step farther, and had shown that when the vegetable acid, oxalic acid, is combined with potash, it forms two compounds, in one of which the acid is contained in twice as great an amount relatively to the potash as in the other. The names _monoxalate_ and _binoxalate_ of potash were applied to these compounds, to indicate the respective proportions of the ingredients."}]}
{"messages": [{"role": "assistant", "content": "The names _monoxalate_ and _binoxalate_ of potash were applied to these compounds, to indicate the respective proportions of the ingredients. Dalton conceived the happy idea that by applying the ancient Greek conception of atoms to such facts the relative weights of the atoms could be determined. Illustrating his views with the two compounds of carbon with hydrogen, marsh gas and olefiant gas, and with the two acids of carbon, carbonic oxide, carbonic “acid,” he regarded the former as a compound of one atom of carbon and one of hydrogen, and the second as a compound of one atom of carbon and two of hydrogen, and similarly for the two oxides of carbon. Knowing the relative weights in which these elements enter into combination, we can deduce the relative weights of the atoms. Placing the relative weight of an atom of hydrogen equal to unity, we have: \n            Marsh     Olefiant  |           Carbonic  Carbonic              Gas        Gas     |            Oxide      Acid   Carbon      6          6      |  Carbon      5          6   Hydrogen    1          2      |  Oxygen      8         16 \nThus the first compound, marsh gas, was regarded by Dalton as composed of an atom of carbon in union with an atom of hydrogen; or, to reproduce his symbols, as ⊜◉; while the second, olefiant gas, on this hypothesis, was a compound of two atoms of hydrogen with one of carbon, or ◉◍◉. Similarly the symbols ◍○, and ○◍○ were given to the two compounds of carbon with oxygen."}]}
{"messages": [{"role": "assistant", "content": "Similarly the symbols ◍○, and ○◍○ were given to the two compounds of carbon with oxygen. So water was assigned the symbol ◉○, for Dalton imagined it to be a compound of one atom of hydrogen with one of oxygen. Compounds containing only two atoms were termed by him “binary”; those containing three, “ternary”; four, “quaternary,” and so on. The weight of an atom of oxygen was eight times that of an atom of hydrogen; while that of an atom of carbon was six times as great as the unit. By assigning symbols to the elements, consisting of the initial letters of their names, or of the first two letters, formulas were developed, indicating the composition of the compound, the atomic weights of the elements being assured. Thus, NaO signified a compound of an atom of sodium (natrium), weighing twenty-three times as much as a similar atom of hydrogen, with an atom of oxygen, possessing eight times the weight of an atom of hydrogen."}]}
{"messages": [{"role": "assistant", "content": "Thus, NaO signified a compound of an atom of sodium (natrium), weighing twenty-three times as much as a similar atom of hydrogen, with an atom of oxygen, possessing eight times the weight of an atom of hydrogen. Therefore, thirty-one pounds of soda should consist of twenty-three pounds of sodium in combination with eight pounds of oxygen, for, according to Dalton, each smallest particle of soda contains an atom of each element, and the proportion is not changed, however many particles be considered. It has been pointed out by Judge Stallo, of Philadelphia, in his _Concepts of Physics_, that such a hypothesis as that of Dalton is no explanation; that a fact of nature, as, for example, the fact of simple and multiple proportions, is not _explained_ by being minified. Allowing the general truth of this statement, it is, nevertheless, undoubted that chemistry owes much to Dalton’s hypothesis—a lucky guess at first, it represents one of the fundamental truths of nature, although its form must be somewhat modified from that in which Dalton conceived it. Dalton’s work was first expounded by Thomas Thomson, professor at Glasgow, in his _System of Chemistry_, published in 1805; and subsequently in Dalton’s own _New System of Chemical Philosophy_, the three volumes of which were published in 1808, in 1810, and in 1827. The determination of these “Constants of Nature” was at once followed out by many chemists, Thomson among the first."}]}
{"messages": [{"role": "assistant", "content": "The determination of these “Constants of Nature” was at once followed out by many chemists, Thomson among the first. But chief among the chemists who have pursued this branch of work was Jacob Berzelius, a Swede, who devoted his long life (1779–1848) to the manufacture of compounds, and to the determination of their composition, or, as it is still termed, the determination of the “atomic weights”—more correctly, “equivalents”—of the elements of which they are composed. It is to him that we owe most of our analytical methods, for, prior to his time, there were few, if any, accurate analyses. Although Lavoisier had devised a method for the analysis of compounds of carbon, viz., by burning the organic compounds in an atmosphere of oxygen contained in a bell-jar over mercury, and measuring the volume of carbon dioxide produced, as well as that of the residual oxygen, Berzelius achieved the same results more accurately and more expeditiously by heating the substance, mixed with chlorate of potassium and sodium chloride, and then estimating the hydrogen as well as the carbon; this process was afterwards perfected by Liebig. Berzelius, however, was able to show that compounds of carbon, like those of other elements, were instances of combination in constant and in multiple proportions. In 1815 two papers were published in the _Annals of Philosophy_ by Dr."}]}
{"messages": [{"role": "assistant", "content": "In 1815 two papers were published in the _Annals of Philosophy_ by Dr. Prout, which have had much influence on the progress of chemistry. They dealt with the figures which were being obtained by Thomson, Berzelius, and others, at that time supposed to represent the “atomic weights” of the elements. Prout’s hypothesis, based on only a few numbers, was that the atomic weights of all elements were multiples of that of hydrogen, taken as unity. There was much dispute regarding this assertion at the time, but as it was contradicted by Berzelius’s numbers, the balance of opinion was against it. But about the year 1840 Dumas discovered an error in the number (12.12) given by Berzelius as the atomic weight of carbon; and with his collaborator, Stas, undertook the redetermination of the atomic weights of the commoner elements—for example, carbon, oxygen, chlorine, and calcium."}]}
{"messages": [{"role": "assistant", "content": "But about the year 1840 Dumas discovered an error in the number (12.12) given by Berzelius as the atomic weight of carbon; and with his collaborator, Stas, undertook the redetermination of the atomic weights of the commoner elements—for example, carbon, oxygen, chlorine, and calcium. This line of research was subsequently pursued alone by Stas, whose name will always be remembered for the precision and accuracy of his experiments. At first Dumas and Stas inclined to the view that Prout’s hypothesis was a just one, but it was completely disproved by Stas’s subsequent work, as well as by that of numerous other observers. It is, nevertheless, curious that a much larger proportion of the atomic weights approximate to whole numbers than would be foretold by the doctrine of chances, and perhaps the last has not been heard of Prout’s hypothesis, although in its original crude form it is no longer worthy of credence. One of the most noteworthy of the discoveries of the century was made by Gay-Lussac (1778–1850) in the year 1808. In conjunction with Alexander von Humboldt, Gay-Lussac had rediscovered about three years before what had previously been established by Cavendish—namely, that, as nearly as possible, two volumes of hydrogen combine with one volume of oxygen to form water, the gases having been measured at the same temperature and pressure."}]}
{"messages": [{"role": "assistant", "content": "In conjunction with Alexander von Humboldt, Gay-Lussac had rediscovered about three years before what had previously been established by Cavendish—namely, that, as nearly as possible, two volumes of hydrogen combine with one volume of oxygen to form water, the gases having been measured at the same temperature and pressure. Humboldt suggested to Gay-Lussac that it would be well to investigate whether similar simple relations exist between the volumes of other gaseous substances when they combine with each other. This turned out to be the case; it appeared that almost exactly two volumes of carbonic oxide unite with one volume of oxygen to form carbon dioxide; that equal volumes of chlorine and hydrogen unite to form hydrochloric acid gas; that two volumes of ammonia gas consist of three volumes of hydrogen in union with one volume of nitrogen, and so on. From such facts, Gay-Lussac was led to make the statement that: The weights of equal volumes of both simple and compound gases, and therefore their densities, are proportional to their empirically found combining weights, or to rational multiples of the latter. Gay-Lussac recognized this discovery of his to be a support for the atomic theory; but it did not accord with many of the then received atomic weights. The assumption that equal volumes of gases contain equal numbers of particles, or, as they were termed by him, _molécules intégrantes_, was made in 1811 by Avogadro, professor of physics at Turin (1776–1856)."}]}
{"messages": [{"role": "assistant", "content": "The assumption that equal volumes of gases contain equal numbers of particles, or, as they were termed by him, _molécules intégrantes_, was made in 1811 by Avogadro, professor of physics at Turin (1776–1856). This theory, which has proved of the utmost importance to the sciences both of physics and of chemistry, had no doubt occurred to Gay-Lussac, and had been rejected by him for the following reasons: A certain volume of hydrogen, say one cubic inch, may be supposed to contain an equal number of particles (atoms) as an equal volume of chlorine. Now these two gases unite in equal volumes. The deduction appears so far quite legitimate that one atom of hydrogen has combined with one atom of chlorine. But the resulting gas occupies two cubic inches, and must therefore contain the same number of particles of hydrogen chloride, the compound of the two elements, as one cubic inch originally contained of hydrogen, or of chlorine. Thus we have two cubic inches containing, of uncombined gases, twice as many particles as is contained in that volume, after combination."}]}
{"messages": [{"role": "assistant", "content": "Thus we have two cubic inches containing, of uncombined gases, twice as many particles as is contained in that volume, after combination. Avogadro’s hypothesis solved the difficulty. By premising two different orders of particles, now termed _atoms_ and _molecules_, the solution was plain. According to him, each particle, or molecule, of hydrogen is a complex, and contains two atoms; the same is the case with chlorine. When these gases combine, or rather _react_, to form hydrogen chloride, the phenomenon is one of a change of partners; the molecule, the double atom, of hydrogen splits; the same is the case with the molecule of chlorine; and each liberated atom of hydrogen unites with a liberated atom of chlorine, forming a compound, hydrogen chloride, which equally consists of a molecule, or double atom. Thus two cubic inches of hydrogen chloride consist of a definite number of molecules, equal in number to those contained in a cubic inch of hydrogen, plus those contained in a cubic inch of chlorine."}]}
{"messages": [{"role": "assistant", "content": "Thus two cubic inches of hydrogen chloride consist of a definite number of molecules, equal in number to those contained in a cubic inch of hydrogen, plus those contained in a cubic inch of chlorine. The case is precisely similar, if other compounds of gases be considered. Berzelius was at first inclined to adopt this theory, and indeed went so far as to change many of his atomic weights to make them fit it. But later he somewhat withdrew from his position, for it appeared to him that it was hazardous to extend to liquids and solids a theory which could be held only of gases. Avogadro’s suggestion, therefore, rested in abeyance until the publication, in 1858, by Cannizzaro, now professor of chemistry in Rome, of an essay in which all the arguments in favor of the hypothesis were collected and stated in a masterly manner. It will be advisable to revert to this hypothesis at a later point, and to consider other guides for the determination of atomic weights."}]}
{"messages": [{"role": "assistant", "content": "It will be advisable to revert to this hypothesis at a later point, and to consider other guides for the determination of atomic weights. In 1819, Dulong (1785–1838), director of the Ecole Polytechnique at Paris, and Petit (1791–1820), professor of physics there, made the discovery that equal amounts of heat are required to raise equally the temperature of solid and liquid elements, provided quantities are taken proportional to their atomic weights. Thus, to raise the temperature of 56 grammes of iron through one degree requires approximately the same amount of heat as is required to raise through one degree 32 grammes of sulphur, 63.5 grammes of copper, and so on; these numbers representing the atomic weights of the elements named. In other words, _equal numbers of atoms have equal capacity for heat_. The number of heat units, or calories (one calory is the amount of heat required to raise the temperature of 1 gramme of water through 1° C.), which is necessary to raise the atomic weight expressed in grammes of any solid or liquid element through 1° C. is approximately 6.2; it varies between 5.7 and 6.6 in actual part."}]}
{"messages": [{"role": "assistant", "content": "is approximately 6.2; it varies between 5.7 and 6.6 in actual part. This affords a means of determining the true value of the atomic weight of an element, as the following example will show: The analysis of the only compound of zinc and chlorine shows that it contains 47.49 per cent. of zinc and 52.16 per cent. of chlorine. Now one grain of hydrogen combines with 35.5 grains of chlorine to form 36.5 grains of hydrogen chloride; and, as already remarked, one volume of hydrogen and one volume of chlorine combine, forming two volumes of hydrogen chloride. Applying Avogadro’s hypothesis, one molecule of hydrogen and one molecule of chlorine react to yield two molecules of hydrogen chloride; and as each molecule is supposed to consist in this case of two atoms, hydrogen chloride consists of one atom of each of its constituent elements."}]}
{"messages": [{"role": "assistant", "content": "Applying Avogadro’s hypothesis, one molecule of hydrogen and one molecule of chlorine react to yield two molecules of hydrogen chloride; and as each molecule is supposed to consist in this case of two atoms, hydrogen chloride consists of one atom of each of its constituent elements. The amount of that element, therefore, which combines with 35.5 grains of chlorine may give the numerical value of the atomic weight of the element, if the compound contains one atom of each element; in that case the formula of the above compound would be zinc, and the atomic weight of zinc, 32.7; but if the formula is ZuCl3, the atomic weight of zinc would be 32.7 × 2; if ZuCl3, 32.7 × 3, and so on. The specific heat of metallic zinc enables this question to be solved. For it has been found, experimentally, to be about 0.095; and 6.2 ÷ 0.095 = 65.2, a close approximation to 32.7 × 2 = 65.4. The conclusion is therefore drawn that zinc chloride is composed of one atom of zinc in combination with two atoms of chlorine, that the atomic weight of zinc is 65.4, and that the molecular weight of zinc chloride is 65.4 + (35.5 × 2) = 136.4. Inasmuch as the relative weight of a molecule of hydrogen is 2 (that of an atom being 1), zinc chloride in the gaseous state should be 136.4 ÷ 2 = 68.2 times that of hydrogen, measured at the same temperature and pressure."}]}
{"messages": [{"role": "assistant", "content": "Inasmuch as the relative weight of a molecule of hydrogen is 2 (that of an atom being 1), zinc chloride in the gaseous state should be 136.4 ÷ 2 = 68.2 times that of hydrogen, measured at the same temperature and pressure. This has been found, experimentally, to be the case. The methods of determining the vapor densities, or relative weights of vapors, are three in number; the first method, due to Dumas (1827), consists in vaporizing the substance in question in a bulb of glass or of porcelain, at a known temperature, closing the bulb while still hot, and weighing it after it is cold. Knowing the capacity of the bulb, the weight of hydrogen necessary to fill it at the desired temperature can be calculated, and the density of the vapor thus arrived at. A second method was devised by Gay-Lussac and perfected by A. W."}]}
{"messages": [{"role": "assistant", "content": "W. Hofmann (1868); and a third, preferable for its simplicity and ease of execution, is due to Victor Meyer (1881). In 1858, as already remarked, Cannizzaro showed the connection between these known facts, and for the first time attention was called to the true atomic weights, which were, up to that time, confused with equivalents, or weights of elements required to replace one unit weight of hydrogen. These were generally regarded as atomic weights by Dalton and his contemporaries. Some exceptions had been observed to the law of Dulong and Petit, viz., beryllium, or glucinium, an element occurring in emeralds; boron, of which borax is a compound; silicon, the component of quartz and flint, and carbon. It was found by Weber that at high temperatures the specific heats of these elements are higher, and the atomic heats approximate to the number of 6.2; but this behavior is not peculiar to these elements, for it appears that the specific heat of all elements increases with rise of temperature."}]}
{"messages": [{"role": "assistant", "content": "It was found by Weber that at high temperatures the specific heats of these elements are higher, and the atomic heats approximate to the number of 6.2; but this behavior is not peculiar to these elements, for it appears that the specific heat of all elements increases with rise of temperature. A certain number of exceptions have also been noticed to the law of Gay-Lussac, which may be formulated: the molecular weight of a compound in a gaseous state is twice its density referred to hydrogen. Thus equal volumes of ammonia and hydrogen chloride unite to form ammonium chloride. It was to be expected that the density should be half the molecular weight, thus: \n    NH3 +  HCl  =  NH4Cl; and 53.5 ÷ 2 = 26.75 = density. (14+3) (1+35.5)  53.5 \nBut the density actually found is only half that number, viz., 13.37; and for long this and similar cases were supposed to be exceptions to the law of Gay-Lussac, viz., that equal volumes of gases at the same pressure expand equally for equal rise of temperature. In other instances the gradual decrease in density with rise of temperature can be followed, as with chloral hydrate, the products of which are chloral and water."}]}
{"messages": [{"role": "assistant", "content": "In other instances the gradual decrease in density with rise of temperature can be followed, as with chloral hydrate, the products of which are chloral and water. It was recognized by St. Claire Deville (1857) that the decrease in density of such mixtures of gases was due, not to their being exceptions to Avogadro’s law, but to the gradual decomposition of the compound body with rise of temperature. To this gradual decomposition he gave the name _dissociation_. This conception has proved of the utmost importance to the science, as will be seen in the sequel. To take the above instance of ammonium chloride, its abnormal density is due to its dissociation into ammonia and hydrogen chloride; and the gas which is obtained on raising its temperature consists, not of gaseous ammonium chloride, but of a mixture of ammonia and hydrogen chloride, which, as is easily seen, occupy, when separate, twice the volume that would be occupied by the gaseous compound."}]}
{"messages": [{"role": "assistant", "content": "To take the above instance of ammonium chloride, its abnormal density is due to its dissociation into ammonia and hydrogen chloride; and the gas which is obtained on raising its temperature consists, not of gaseous ammonium chloride, but of a mixture of ammonia and hydrogen chloride, which, as is easily seen, occupy, when separate, twice the volume that would be occupied by the gaseous compound. Of recent years it has been shown by Brereton Baker that, if perfectly free from moisture, ammonium chloride gasifies as such, and that its density in the state of vapor is, in fact, 26.75. The molecular complexity of gases has thus gradually become comprehended, and the truth of Avogadro’s law has gained acceptance. And as a means of picturing the behavior of gaseous molecules, the “Kinetic Theory of Gases” has been devised by Joule, Clausius, Maxwell, Thomson (Lord Kelvin), and others. On the assumption that the pressure of a gas on the walls of the vessel which contains it is due to the continued impacts of its molecules, and that the temperature of a gas is represented by the product of the mass of the molecules, or the square of their velocity, it has been possible to offer a mechanical explanation of Boyle’s law, that at constant temperature the volume of a gas diminishes in proportion as the pressure increases; of Gay-Lussac’s law, that all gases expand equally for equal rise of temperature, provided pressure is kept constant; the condition being that equal volumes of gases contain equal numbers of molecules. A striking support is lent to this chain of reasoning by the facts discovered by Thomas Graham (1805–1869), professor at University College, London, and subsequently master of the Royal Mint."}]}
{"messages": [{"role": "assistant", "content": "A striking support is lent to this chain of reasoning by the facts discovered by Thomas Graham (1805–1869), professor at University College, London, and subsequently master of the Royal Mint. Graham discovered that the rate of diffusion of gases into each other is inversely as the square roots of their densities. For instance, the density of hydrogen being taken as unity, that of oxygen is sixteen times as great; if a vessel containing hydrogen be made to communicate with one containing oxygen, the hydrogen will pass into the oxygen and mix with it; and, conversely, the oxygen will pass into the hydrogen vessel. This is due to the intrinsic motion of the molecule of each gas. And Graham found, experimentally, that for each volume of oxygen which enters the hydrogen vessel four volumes of hydrogen will enter the oxygen vessel. Now, 4 = √16; and as these masses are relatively 1 and 16, and their temperatures are equal, the square of their velocities are respectively 1 and 16."}]}
{"messages": [{"role": "assistant", "content": "Now, 4 = √16; and as these masses are relatively 1 and 16, and their temperatures are equal, the square of their velocities are respectively 1 and 16. The question of the molecular complexity of gases being thus disposed of, it remains to be considered what are the relative complexity of liquid molecules. The answer is indicated by a study of the capillary phenomena of liquids, one method of measuring which is the height of their ascent in narrow or capillary tubes. We shall not enter here into detail as to the method and arguments necessary; suffice it to say that the Hungarian physicist Eötvös was the first to indicate the direction of research, and that Ramsay and Shields succeeded in proving that the complexity of the molecules of most liquids is not greater than that of the gases which they form on being vaporized; and also that certain liquids, _e.g._, water, the alcohols, and other liquids, are more or less “associated,” _i.e._, their molecules occur in couplices of two, three, four, or more, and as the temperature is raised the complexity of molecular structure diminishes. As regards the molecular complexity of solids, nothing definite is known, and, moreover, there appears to be no method capable of revealing it. While the researches of which a short account has now been given have led to knowledge regarding the nature of molecules, the structure of the molecule has excited interest since the early years of the century, and its investigation has led to important results."}]}
{"messages": [{"role": "assistant", "content": "While the researches of which a short account has now been given have led to knowledge regarding the nature of molecules, the structure of the molecule has excited interest since the early years of the century, and its investigation has led to important results. The fact of the decomposition of acidified water by an electric current, discovered by Nicholson and Carlisle, and of salts into “bases” and “acids” by Berzelius and Hisinger in 1803, led to the belief that a close connection exists between electric energy, or, as it was then termed, “electric force,” and the affinity which holds the constituents of chemical compounds in combination. In 1807 Davy propounded the theory that all compounds consist of two portions, one electro-positive and the other electro-negative. This idea was the result of experiments on the behavior of substances, such, for example, as copper and sulphur—if portions of these elements be insulated and then brought into contact they become oppositely electrified. The degree of electrification is intensified by rise of temperature until, when combination ensues, the electrification vanishes. Combination, therefore, according to Davy, is concurrent with the equalization of potentials."}]}
{"messages": [{"role": "assistant", "content": "Combination, therefore, according to Davy, is concurrent with the equalization of potentials. In 1812 Berzelius brought forward an electro-chemical theory which for the following twenty years was generally accepted. His primary assumption was that the atoms of elements, or, in certain cases, groups of atoms, are themselves electrified; that each atom, or group of atoms, possesses two poles, one positive, the other negative; that the electrification of one of these poles predominates over that of the other, so that the atom or group is itself, as a whole, electro-positive, or electro-negative; that combination ensued between such oppositely electrified bodies by the neutralization, partial or complete, of their electric charges; and, lastly, that the polarity of an element or group could be determined by noting whether the element or group separated at the positive or at the negative pole of the galvanic battery, or electrolysis. For Berzelius, oxygen was the most electro-negative and potassium the most electro-positive of the elements, the bridge between the “non-metals” and the “metals” being hydrogen, which, with nitrogen, forms a basic, or electro-positive, group, while with chlorine, etc., it forms electro-negative groups. The fact that an electric current splits compounds in solution into two portions led Berzelius to devise his “dualistic” system, which involved the assumption that all compounds consist of two portions, one electro-positive, the other electro-negative. Thus sulphate of magnesium and potassium was to be regarded as composed of electro-positive potassium sulphate in combination with electro-negative magnesium sulphate; the former in its turn consisted of electro-negative sulphur trioxide (SO3) in combination with electro-positive oxide of potassium (K2O); while each of these proximate constituents of potassium sulphate were themselves composed of the electro-negative oxygen in combination with electro-positive sulphur, or potassium."}]}
{"messages": [{"role": "assistant", "content": "Thus sulphate of magnesium and potassium was to be regarded as composed of electro-positive potassium sulphate in combination with electro-negative magnesium sulphate; the former in its turn consisted of electro-negative sulphur trioxide (SO3) in combination with electro-positive oxide of potassium (K2O); while each of these proximate constituents of potassium sulphate were themselves composed of the electro-negative oxygen in combination with electro-positive sulphur, or potassium. On contrasting sulphur with potassium, however, the former was considered more electro-negative than the latter; so that the group SO3 as a whole was electro-negative, while K2O was electro-positive. The symbols given above, which are still in universal use, were also devised by Berzelius for the purpose of illustrating and emphasizing his views. These views, however, met with little acceptance at the time in England. Lavoisier’s idea, that oxygen was the necessary constituent of all acids, began about this time to lose ground. For Davy had proved the elementary nature of chlorine; and hydrochloric acid, one of the strongest, was thus seen to contain no oxygen, and Davy expressed the view, founded on his observation, that iodic “acid,” I2O5, was devoid of acid properties until dissolved in water, and that the essential constituent of all acids was hydrogen, not oxygen."}]}
{"messages": [{"role": "assistant", "content": "For Davy had proved the elementary nature of chlorine; and hydrochloric acid, one of the strongest, was thus seen to contain no oxygen, and Davy expressed the view, founded on his observation, that iodic “acid,” I2O5, was devoid of acid properties until dissolved in water, and that the essential constituent of all acids was hydrogen, not oxygen. The bearing of this theory on the dualistic theory is, that while, _e.g._, sulphuric acid was regarded by Berzelius as SO3, containing no hydrogen, and was supposed to be separated as such at the positive pole of a battery, Davy’s suggestion led to the opposite conclusion that the formula of sulphuric acid is H2SO4, and that by the current it is resolved into H2 and SO4. Faraday’s electrolytic law, that when a current is passed through electrolytes in solution the elements are liberated in quantities proportional to their equivalents, led to the abandonment of the dualistic theory. For when a current is passed in succession through acidified water, fused lead chloride, and a solution of potassium sulphate, the quantities of hydrogen and oxygen from the water, of lead and chlorine from the lead chloride, and the potassium of the sulphate are in accordance with Faraday’s law. But in addition to the potassium there is liberated at the same pole an equivalent of hydrogen. Now, if Berzelius’s theory be true, the products should be SO3 and K2O, but if the opposite view be correct, then K2 is liberated first and by its subsequent action on water it yields potash and its equivalent of hydrogen."}]}
{"messages": [{"role": "assistant", "content": "Now, if Berzelius’s theory be true, the products should be SO3 and K2O, but if the opposite view be correct, then K2 is liberated first and by its subsequent action on water it yields potash and its equivalent of hydrogen. This was pointed out first by Daniell, professor at King’s College, London, and it was regarded as a powerful argument against Berzelius’s system. In 1833, too, Graham investigated the phosphoric acids, and prepared the salts of three, to which he gave the names, _ortho-_, _pyro-_, and _meta-_ phosphoric acids. To understand the bearing of this on the doctrine of dualism it must be remembered that P2O5, pentoxide of phosphorus, was at that date named phosphoric acid. When dissolved in water it reacts with bases, forming salts—the phosphates. But the quantity of water necessary was not then considered essential; Graham, however, showed that there exist three series of salts—one set derived from P2O5,3H2O, one from P2O5,2H2O, and a third from P2O5,H2O."}]}
{"messages": [{"role": "assistant", "content": "But the quantity of water necessary was not then considered essential; Graham, however, showed that there exist three series of salts—one set derived from P2O5,3H2O, one from P2O5,2H2O, and a third from P2O5,H2O. His way of stating the fact was that water could play the part of a base; for example, the ordinary phosphate of commerce possessed, according to him, the formula P2O5,2Na2O,H2O, two-thirds of the “water of constitution” being replaced by oxide of sodium. Liebig, then professor at Giessen (1803–1873), founded on these and on similar observations of his own the doctrine of poly-basic acids—acids in which one, two, three, or more atoms of hydrogen were replaceable by metals. Thus, instead of writing, as Graham did, P2O5,2Na2O,H2O, he wrote, PO4Na2H; and for orthophosphoric acid PO4H3. The group of atoms (PO4), therefore, existed throughout the whole series of orthophosphates, and could exist in combination with hydrogen, with hydrogen and metals, or with metals alone. Similarly the group (P2O7) was characteristic of pyrophosphates and (PO3) of metaphosphates, for P2O5,2H2O=(P2O7)H4; and P2O5,H2O=2(PO3)H."}]}
{"messages": [{"role": "assistant", "content": "Similarly the group (P2O7) was characteristic of pyrophosphates and (PO3) of metaphosphates, for P2O5,2H2O=(P2O7)H4; and P2O5,H2O=2(PO3)H. The first clear ideas of the structure of the molecule were, however, gained from the study of the compounds of carbon. It was difficult to apply the dualistic theory to them. For few of them are electrolytes, and therefore their products of electrolysis, being non-existent, could not be classified. Nevertheless, Gay-Lussac regarded alcohol, C2H6O, as a compound of C2H4, ethylene, and H2O, water; and oxalic acid (anhydrous), C2O3, as one of CO2 with CO. The discovery of “isomeric compounds,” _i.e._, of compounds which possess the same ultimate formula and yet differ entirely in their properties, forced upon chemists the necessity of attending to the structure of the molecule; for only by such a supposition could the difference between two isomeric bodies be explained."}]}
{"messages": [{"role": "assistant", "content": "The discovery of “isomeric compounds,” _i.e._, of compounds which possess the same ultimate formula and yet differ entirely in their properties, forced upon chemists the necessity of attending to the structure of the molecule; for only by such a supposition could the difference between two isomeric bodies be explained. In 1823 Liebig discovered that silver fulminate and silver cyanate both possessed the empirical formula AgCNO; in 1825 this was followed by the discovery by Faraday that oil gas contains a hydrocarbon identical in composition with ethylene, C2H4, yet differing from it in properties; and in 1829 Wöhler, professor in Göttingen (1800–1882), discovered that urea, a constituent of urine, could be produced by heating ammonium cyanate, NH4CNO, a substance of the same formula. It therefore became clear that the identity of a compound must depend on some other cause than its ultimate composition. In 1833 Liebig and Wöhler took an important step in elucidating this question by their investigations on benzoic acid and acid obtainable by distilling a resin named gum benzoin. They showed that this acid, C7H6O2, could be conceived as consisting of the group C7H5O, to which they gave the name “benzoyl,” in combination with OH; that benzoic aldehyde, C7H6O, might be regarded as its compound with hydrogen; that it also formed compounds with chlorine, and bromine, and sulphur, and replaced hydrogen in ammonia (C7H6O,NH2). They termed this group, benzoyl, a “compound element” or a “radical.” This research was followed by one by Robert Bunsen, professor at Heidelberg, born in 1811, and recently (1899) dead, which bore reference to cacodyl, a compound of arsenic, carbon and hydrogen, in which the idea of a radical was confirmed and amplified."}]}
{"messages": [{"role": "assistant", "content": "They termed this group, benzoyl, a “compound element” or a “radical.” This research was followed by one by Robert Bunsen, professor at Heidelberg, born in 1811, and recently (1899) dead, which bore reference to cacodyl, a compound of arsenic, carbon and hydrogen, in which the idea of a radical was confirmed and amplified. The idea of a radical having thus become established, Jean Baptiste Andrée Dumas, professor in Paris (1800–1884), propounded the theory of “substitution,” _i.e._, that an element such as chlorine or oxygen (which, be it noticed, is electro-negative on Berzelius’s scale) could replace hydrogen in carbon compounds, atom for atom, the resulting compound belonging to the same “type” as the one from which it was derived. And Laurent, warden of the mint at Paris (1807–1853), and Gerhardt, professor at Montpelier and at Strasburg (1816–1856), emphasized the fact that one element, be it what it may, can replace another without fundamentally altering its chemical character, and also that an atom of hydrogen can be replaced by a group of atoms or radical, behaving for the occasion like the atom of an element. It is to Laurent and Gerhardt that we owe the definition of an atom—_the smallest quantity of an element which can be present in a compound_; an equivalent—_that weight of an element which combines with or replaces one part by weight of hydrogen_; and a molecule—_the smallest quantity which can exist in a free state, whether of an element or a compound_. They recognized, too, that a molecule of hydrogen, chlorine, etc., consists of two atoms. In 1849 Wurtz, professor in Paris (1817–1884), and Hofmann, then professor in the College of Chemistry in London, afterwards at Berlin (1818–1892), discovered a series of compounds allied to ammonia, NH3, in which one or more atoms of hydrogen were replaced by a group or radical, such as methyl (CH3), ethyl (C2H5), or phenyl (C6H5)."}]}
{"messages": [{"role": "assistant", "content": "In 1849 Wurtz, professor in Paris (1817–1884), and Hofmann, then professor in the College of Chemistry in London, afterwards at Berlin (1818–1892), discovered a series of compounds allied to ammonia, NH3, in which one or more atoms of hydrogen were replaced by a group or radical, such as methyl (CH3), ethyl (C2H5), or phenyl (C6H5). Wurtz referred such compounds to the ammonia “type.” They all resemble ammonia in their physical properties—smell, taste, etc.—as well as in their power of uniting with acids to form salts resembling ammonium chloride (NH4Cl), and other ammonium compounds. Shortly afterwards Williamson, professor at University College, London, added the “water type,” in consequence of his researches on “mixed ethers”—bodies in which the hydrogen of water might be regarded as replaced by organic radicals. Thus we have the series: \nH. O. H.; CH3."}]}
{"messages": [{"role": "assistant", "content": "H.; CH3. O. H.; CH3. O. CH3; and NH3; NH2; H3; NH(CH3)2; and N(CH3)3; the first representing compounds following the water type, the latter the ammonia type. This suggestion had been previously made by Laurent, in 1846."}]}
{"messages": [{"role": "assistant", "content": "This suggestion had been previously made by Laurent, in 1846. But Williamson extended his views to inorganic compounds; thus, sulphuric acid was represented as constructed on the double water type—HO. SO2. OH, being derived from H. O. (H."}]}
{"messages": [{"role": "assistant", "content": "(H. H) O. H, the two hydrogen atoms enclosed in brackets being replaced by the radical SO2. To these types Gerhardt added the hydrogen and hydrogen chloride types, H.H. and H.Cl; and, later, Kekulé, professor in Bonn (1829), added the marsh gas type C(H)4. The next important step was taken by Frankland, professor in the Royal School of Mines, London; his work, however, had been anticipated by Cunn Brown, professor at Edinburgh University, in a pamphlet even yet little known."}]}
{"messages": [{"role": "assistant", "content": "The next important step was taken by Frankland, professor in the Royal School of Mines, London; his work, however, had been anticipated by Cunn Brown, professor at Edinburgh University, in a pamphlet even yet little known. It was to attribute to elements one or more powers of combination. To these he gave the name “valency,” and the capacity of possessing valency was called “quantivalence.” Thus hydrogen was taken as a “monad,” or monovalent. Chlorine, because it unites with hydrogen atom to atom, is also a monad. Oxygen, having the power to combine with two atoms of hydrogen, was termed a dyad, or divalent; nitrogen a triad, or trivalent; carbon a tetrad, or tetravalent, and so on. This is evident from inspection of the formulas of their compounds with hydrogen, thus: \n                         H     H   H                         /       \\ /   H——Cl;  H——O——H;  H——N   ;     C                         \\       / \\                          H     H   H \nInstances of penta, hexa, and even hepta-valency are not wanting."}]}
{"messages": [{"role": "assistant", "content": "This is evident from inspection of the formulas of their compounds with hydrogen, thus: \n                         H     H   H                         /       \\ /   H——Cl;  H——O——H;  H——N   ;     C                         \\       / \\                          H     H   H \nInstances of penta, hexa, and even hepta-valency are not wanting. This was the key to unlock the structure of chemical compounds; and Frankland’s views, just stated, are still held by chemists. The determination of the constitution of compounds, chiefly those of carbon, occupied the attention of chemists, almost exclusively, until 1880. The plan of action is much the same as that of a mechanician who wishes to imitate a complicated mechanism. He must first dissect it into groups of mechanical contrivances; these are next constructed; and they are finally built together into the complete machine. In certain cases the atoms of carbon are arranged in “chains,” as, for example, in pentyl alcohol: \n  H3C——C——C——C——C——O——H           H2 H2 H2 H2 \neach atom being tetrad, and its “affinities,” or powers of combination, saturated either with hydrogen or with those of neighboring atoms of carbon; in others they are in the form of a “ring,” as in benzene, the formula of which was first suggested by Kekulé, viz.: \n     H  H      C——C     /    \\   HC      CH;     \\    /      C==C      H  H \nor in both, as in ethyl benzene, \n     H  H      C——C     /    \\   H  H   HC      C——C——CH."}]}
{"messages": [{"role": "assistant", "content": "In certain cases the atoms of carbon are arranged in “chains,” as, for example, in pentyl alcohol: \n  H3C——C——C——C——C——O——H           H2 H2 H2 H2 \neach atom being tetrad, and its “affinities,” or powers of combination, saturated either with hydrogen or with those of neighboring atoms of carbon; in others they are in the form of a “ring,” as in benzene, the formula of which was first suggested by Kekulé, viz.: \n     H  H      C——C     /    \\   HC      CH;     \\    /      C==C      H  H \nor in both, as in ethyl benzene, \n     H  H      C——C     /    \\   H  H   HC      C——C——CH. \\    /   H  H      C==C      H  H \nOne or more atoms of nitrogen, or of oxygen, may form part of the circle, as in pyridine: \n    H  H                       H  H     C——C                       C  C    /    \\                     /   N      CH  and furfurane,  O  ==  ,    \\    /                     \\     C==C                       C  C     H  H                       H  H \nand so on. By means of conceptions such as these many interesting compounds have been built up out of the elements which they contain; _e.g._, urea and uric acid, constituents of urine; theobromine and caffeine, the essential principles of cocoa and tea; alizarine and indigo, valuable dyestuffs; and several of the alkaloids, bitter principles contained in plants, of great medicinal value. They have led, too, to the discovery of many brilliant colors, now almost universally employed, to the exclusion of those less brilliant, because less pure, derived from plants, and in one or two cases from animals; the manufacture of gun-cotton, dynamite, and similar high explosives; and to the development of the candle industry; the sugar manufacture; to improvement in tanning, in brewing, and in the preparation of gas and oils for illuminating purposes. In short, it may be said that the industrial progress of the latter half of the century has been due to the theoretical views of which a short sketch has just been given. Such formulas, however, can evidently not represent the true constitution of matter, inasmuch as the atoms are imagined to lie on a plane, whereas it is evident that they must occupy space of three dimensions and possess the attributes of solidity."}]}
{"messages": [{"role": "assistant", "content": "Such formulas, however, can evidently not represent the true constitution of matter, inasmuch as the atoms are imagined to lie on a plane, whereas it is evident that they must occupy space of three dimensions and possess the attributes of solidity. The conception which led to the formulation of such views was due first to Pasteur, in his later years director of the institute known by his name at Paris, and more directly to LeBel and Van’t Hoff, now professor at Berlin, independently of each other. In 1848 Pasteur discovered that it was possible to separate the two varieties of tartaric acid from each other; and that that one which rotated the plane of polarized light to the right gave crystals with an extra face, unsymmetrically disposed with regard to the other faces of the crystal. The variety, the solution of which in water was capable of producing left-handed rotation, also possessed a similar face, but so placed that its reflection in a mirror reproduced the right-handed variety. Pasteur also showed that a mixture of these acids gave crystals not characterized by an unsymmetrically placed face; and also that the solution was without action on polarized light. These observations remained unexplained, until LeBel and Van’t Hoff, in 1874, simultaneously and independently devised a theory which has, up till now, stood the test of research."}]}
{"messages": [{"role": "assistant", "content": "These observations remained unexplained, until LeBel and Van’t Hoff, in 1874, simultaneously and independently devised a theory which has, up till now, stood the test of research. It is briefly this: Imagine two regular tetrahedra, or three-sided pyramids, standing each on its triangular base. An idea can best be got by a model, easily made by laying on a table three lucifer matches so as to form an equilateral triangle, and erecting a tripod with three other matches, so that each leg of the tripod stands on one corner of the triangle. At the centre of such a tetrahedron, an atom of carbon is supposed to be placed. Marsh gas, CH4, is supposed to have such a structure, each corner, or solid angle of the structure (of which there are four), being occupied by an atom of hydrogen. This represents the solid or _stereochemical_ formula of methane or marsh gas."}]}
{"messages": [{"role": "assistant", "content": "This represents the solid or _stereochemical_ formula of methane or marsh gas. Now, suppose one of the atoms of hydrogen in each of these structures to be replaced by chlorine, the group (OH), or any other monovalent element or group. It is evident that if not exactly similar (owing to the replacement not having been made at similar corners in each), the two structures can be made similar by turning one of them round, until the position of the substituting atom or group (which we will term X) coincides in position with X in the stationary one. If two such replacements be made, say, with X and Y in each, coincidence can again be made to take place; but the same is not the case if X, Y, and Z replace three atoms of hydrogen in the structure; for there is one way of replacement which is the optical image of the other, and represents the other’s reflection in a mirror. [Illustration: (Tetrahedron XYZ) and (Tetrahedron XZY)] \nNow, it is found that when the four corners of such a structure are occupied by four separate atoms or groups, or when (as the expression goes) the body contains an “asymmetrical carbon atom,” if the substance or one of its derivations can be obtained in a crystalline form, the crystals are also asymmetric, _i.e._, arc develops a face which is the mirror-reflection of a similar face developed on the other variety; and if a beam of polarized light be passed through the solution of the substance, its plane is rotated to the left if one variety be used, and, if the other, to the right. This hypothesis of LeBel’s and Van’t Hoff’s has had an enormous influence on the progress of organic chemistry."}]}
{"messages": [{"role": "assistant", "content": "This hypothesis of LeBel’s and Van’t Hoff’s has had an enormous influence on the progress of organic chemistry. By its means Fischer, now professor at Berlin, has explained the reason of the existence of the enormous number of bodies analogous to grape and cane sugar, and has prepared many new varieties; and it appears likely that the terpenes, a class of bodies allied to turpentine, and comprising most of the substances to which the odor of flowers is due, may thereby find their explanation. It may be mentioned in passing that Pasteur, having found that ordinary mould destroyed one variety of tartaric acid rather than the other in a mixture of the two, and made use of this observation in order to prepare the unattached variety in a state of purity, was led to study the action of organisms more or less resembling mould; and that this has led to the development of the science of bacteriology, which has had an enormous influence on our views regarding fermentation in general, and guides the work of our physicians, our surgeons (witness Lister’s antiseptic treatment), our sanitary engineers in their estimate of the purity of drinking-water and of the disposal of sewage, of our manufacturers of beer and spirits, of wine-growers, and more recently of farmers. All these processes depend upon the action of organisms in producing chemical changes, whether in the tissues of the body, causing or curing disease, or in the production of flavored alcohol from sugar, or in the manufacture of butter and cheese, or in preparing the land for the reception of crops. We also owe to the genius of Van’t Hoff the most important advance of recent times in the region of physical chemistry. It has been observed by Raoult, professor at Grenoble, that the freezing-point of a solvent as a general rule is lowered to the same extent if there be dissolved in it quantities of substances proportional to their molecular weights."}]}
{"messages": [{"role": "assistant", "content": "It has been observed by Raoult, professor at Grenoble, that the freezing-point of a solvent as a general rule is lowered to the same extent if there be dissolved in it quantities of substances proportional to their molecular weights. Thus, supposing 1.80 grams of grape-sugar be dissolved in 100 grams of water and the solution cooled below 0° with constant stirring, ice separates suddenly in thin spicules, and the temperature rises to −0.185°. If 3.42 grams of cane-sugar be similarly dissolved in 100 grams of water, the freezing-point of the solution is again −0.185°. Now, 1.80 and 3.42 are respectively the hundredth part of the molecular weights of grape-sugar (C6H12O6) and cane-sugar (C12H22O11). Similarly, Raoult found that quantities proportional to molecular weights dissolved in a solvent depress the vapor pressure of that solvent equally, or, what comes to the same thing, raise its boiling-point by an equal number of degrees. But ordinary salts, such as sodium chloride, potassium nitrate, etc., dissolved in water, give too great a depression of the freezing-point and too high a boiling-point."}]}
{"messages": [{"role": "assistant", "content": "But ordinary salts, such as sodium chloride, potassium nitrate, etc., dissolved in water, give too great a depression of the freezing-point and too high a boiling-point. Next, it has been observed by botanists, Devries, Pfeffer, and others, who had examined the ascent of sap in plants, that if a vessel of unglazed porcelain, so treated as to cause a film of cupric ferrocyanide (a slimy red compound) to deposit in the pores of its walls, be filled with a weak (about 1 per cent.) solution of sugar or similar substance, and plunged in a vessel of pure water, water entered through the pores. By attaching a monometer to the porous vessel the pressure exerted by the entering water could be measured. Such pressure was termed “osmotic pressure,” referring to the “osmosis” or passage through the walls of the vessel. Such prepared walls are permeable freely to water, but not to sugar or similar bodies. Van’t Hoff pointed out that the total pressure registered is proportional to the amount of substance in solution, and that it is proportional to the absolute temperature, and he showed, besides, that the pressure exerted by the sugar molecules is the same as that which would be exerted at the same temperature were an equal number of molecules of hydrogen to occupy the same volume as the sugar solution."}]}
{"messages": [{"role": "assistant", "content": "Van’t Hoff pointed out that the total pressure registered is proportional to the amount of substance in solution, and that it is proportional to the absolute temperature, and he showed, besides, that the pressure exerted by the sugar molecules is the same as that which would be exerted at the same temperature were an equal number of molecules of hydrogen to occupy the same volume as the sugar solution. This may be expressed by stating that when in dilute solution sugar molecules behave _as if_ they were present in the gaseous state. Here again, however, it was noticed that salts tended to give a higher pressure; it was difficult to construct a semi-permeable diaphragm, however, which would resist the passage of salt molecules, while allowing those of water to pass freely. Lastly, Arrhenius, of Stockholm, had shown that the conductivity of salt solutions for electricity may be explained on the assumption that when a salt, such as KNO3 is dissolved in water, it dissociates into portions similar in number and kind to those it would yield if electrolyzed (and if no secondary reactions were to take place). Such portions (K and NO3, for example) had been named ions by Faraday. The conductivity of such solutions becomes greater, per unit of dissolved salt, the weaker the solution, until finally a limit is reached, after which further dilution no longer increases conductivity."}]}
{"messages": [{"role": "assistant", "content": "The conductivity of such solutions becomes greater, per unit of dissolved salt, the weaker the solution, until finally a limit is reached, after which further dilution no longer increases conductivity. Now Van’t Hoff united all these isolated observations and showed their bearing on each other. Stated shortly, the hypothesis is as follows: When a substance is dissolved in a large quantity of a solvent, its molecules are separated from each other to a distance comparable with that which obtains in gases. They are, therefore, capable of independent action; and when placed in a vessel the walls of which are permeable to the solvent, but not to the dissolved substance (“semi-permeable membrane”), the imprisoned molecules of the latter exert pressure on the interior surface of these walls as if they were gaseous. Van’t Hoff showed the intimate connection between this phenomenon and the depression of freezing-point and the use of vapor pressure already alluded to. He pointed out further that the exceptions to this behavior, noticed in the case of dissolved salts, are due to their “electric dissociation,” or “ionization,” as it is now termed; and that in a sufficiently dilute solution of potassium nitrate, for example, the osmotic pressure, and the correlated depression of freezing-point and rise of boiling-point, are practically equal to what would be produced were the salt to be split into its ions, K and NO3."}]}
{"messages": [{"role": "assistant", "content": "He pointed out further that the exceptions to this behavior, noticed in the case of dissolved salts, are due to their “electric dissociation,” or “ionization,” as it is now termed; and that in a sufficiently dilute solution of potassium nitrate, for example, the osmotic pressure, and the correlated depression of freezing-point and rise of boiling-point, are practically equal to what would be produced were the salt to be split into its ions, K and NO3. These views were vigorously advocated by Ostwald, professor at Leipzig, in his _Zeitschrift für physikalische Chemie_, and he and his pupils have done much to gather together facts in confirmation of this theory, and in extending its scope. It must be understood that the ions K and NO3 are not, strictly speaking, atoms; they are _charged_ atoms; the K retains a +, and the NO3 a − charge. On immersing into the solution the poles of a battery, one charged + and the other −, the + K atoms are attracted to the − pole, and are there discharged; as soon as they lose their charge they are free to act on the water, when they liberate their equivalent of hydrogen. Similarly, the − NO3 groups are discharged at the + pole, and abstract hydrogen from the water, liberating an equivalent quantity of oxygen. Thus the phenomenon of electrolysis, so long a mysterious process, finds a simple explanation."}]}
{"messages": [{"role": "assistant", "content": "Thus the phenomenon of electrolysis, so long a mysterious process, finds a simple explanation. The course of ordinary chemical reactions is also readily realized when viewed in the light of this theory. Take, for example, the ordinary equation: \n  AgNO3.Aq + NaCl.Ag = AgCl + NaNO3.Aq; \n_i.e._, solutions of silver nitrate and sodium chloride give a precipitate of silver chloride, leaving sodium nitrate in solution. By the new views, such an equation must be written: \n  +       −        +       −              +       −   Ag.Aq + NO3.Aq + Na.Aq + Cl.Aq = AgCl + Na.Aq + NO3.Aq. The compound, silver chloride, being insoluble in water, is formed by the union of the ions Ag and Cl, and their consequent discharge, forming an electrically neutral compound; while the sodium ions, charged positively together with the NO3 ions, negatively charged, remain in solution. One more application of the principle may be given."}]}
{"messages": [{"role": "assistant", "content": "One more application of the principle may be given. Many observers—Andrews, Favre, and Silbermann, but especially Julius Thomsen, of Copenhagen, and M. Berthelot, of Paris—have devoted much labor and time to the measurement of the heat evolved during chemical reactions. Now, while very different amounts of heat are evolved when chlorine, bromine, or iodine combine respectively with sodium or potassium, the number of heat units evolved on neutralizing sodium or potassium hydroxide with hydrochloric, hydrobromic, hydriodic, or nitric acids is always about 13,500. How can this fact be explained? It finds its explanation as follows: These acids and bases are ionized in solution as shown in the equation: \n  +      −        +       −              +       −   H.Aq + Cl.Aq."}]}
{"messages": [{"role": "assistant", "content": "It finds its explanation as follows: These acids and bases are ionized in solution as shown in the equation: \n  +      −        +       −              +       −   H.Aq + Cl.Aq. + Na.Aq + OH.Aq = H.OH + Na.Aq + Cl.Aq. Water is the only compound formed; and it is produced by the union of the hydrogen-ion originally belonging to the acid, and the OH or hydroxyl-ion originally belonging to the base. No further change has occurred; hence the uniform evolution of heat by the interaction of equivalent quantities of these acids and bases. It now remains to give a short account of the greatest generalization which has as yet been made in chemistry. It has been termed the “Periodic Arrangement of the Elements.” \nIn 1864 Newlands, of London, and Lothar Meyer, late of Tübingen, found that by arranging the elements in the order of their atomic weights certain regularities were to be observed between each element, and in general the eighth in succession from it, in the order of their numerical value."}]}
{"messages": [{"role": "assistant", "content": "It has been termed the “Periodic Arrangement of the Elements.” \nIn 1864 Newlands, of London, and Lothar Meyer, late of Tübingen, found that by arranging the elements in the order of their atomic weights certain regularities were to be observed between each element, and in general the eighth in succession from it, in the order of their numerical value. Such similar elements formed groups or quantities; while the elements separating them belong to a _period_, hence the name “periodic arrangement.” Commencing with lithium, a light, lustrous metal found in silicate in certain minerals, we have the following series: \n  Lithium Beryllium Boron    Carbon  Nitrogen   Oxygen  Fluorine Neon      7       9.2      11       12       14        16       19     20 \n  Sodium  Magnesium Aluminum Silicon Phosphorus Sulphur Chlorine Argon     23      24.3      27       28       31        34      35.5    40 \nand so on. It is unnecessary to point out in detail the resemblances between the elements which stand in the vertical columns; but it may be stated that the resemblance extends also to the formulas and properties of their compounds. Thus the chlorides of lithium and sodium are each white soluble salts, of the formulas LiCl and NaCl; oxides of magnesium and of beryllium are both insoluble white earthy powders, MgO and BeO (GeO), and so on. Newlands, in his preliminary sketch, termed this order the “Law of Octaves,” and predicted the existence of certain undiscovered elements which should occupy unfilled positions in the table. Mendeléef, professor at St."}]}
{"messages": [{"role": "assistant", "content": "Mendeléef, professor at St. Petersburg, in 1869 amplified and extended these relations; and he and Meyer pointed out that the volume occupied by equal numbers of atoms of such elements underwent a periodic variation when the elements are classified as above. The prediction of undiscovered elements was made by Mendeléef in a more assured manner; and in several cases they have been realized. Thus what Mendeléef called “ekaboron” has since been discovered by Lecoq de Boisbandron and named, patriotically, “gallium”; Mendeléef’s “eka-silicon” is now known as “germanium,” discovered by Winkler; and “eka-aluminum” is now Cléve’s “scandium.” Moreover, the atomic weights of cæsium, beryllium, molybdenium, and mercury have been altered so that they fit the periodic table; and further research has justified the alteration. The valency of these elements increases from right to left, as will be seen by inspection of the following series: \n  LiCl     BeCl3    BCl3     CCl4              NH4Cl   Na2O     MgO      B2O3     SiO2              PCl3   Monad. Dyad."}]}
{"messages": [{"role": "assistant", "content": "Dyad. Triad. Tetrad. Triad and Pentad. OH2                  FH                Ne——         SO3               Cl(OH)O3             A——     Dyad and Hexad. Monad and Heptad."}]}
{"messages": [{"role": "assistant", "content": "Monad and Heptad. No valency. The elements of no valency are of recent discovery. In 1894 Lord Rayleigh had determined the density of the nitrogen of the atmosphere, having separated from it the oxygen and carbon dioxide which is mixed with nitrogen in air. He found it to be of somewhat higher density than that obtainable from ammonia and other compounds of nitrogen. In conjunction with Ramsay he investigated atmospheric nitrogen; it was absorbed either by a method devised by Cavendish, or by making it combine with magnesium at a red heat."}]}
{"messages": [{"role": "assistant", "content": "In conjunction with Ramsay he investigated atmospheric nitrogen; it was absorbed either by a method devised by Cavendish, or by making it combine with magnesium at a red heat. They found that the unabsorbable residue possessed an unknown spectrum, and that its density was nearly 20. To this new gas they gave the name “argon,” or inactive, seeing that all attempts to cause it to enter into combination had failed. In 1895 Ramsay, searching for possible combinations of argon in minerals, experimented with one which had been previously examined by Hillebrand, of Baltimore, and obtained from it helium, a gas of density 2, possessing a spectrum which had been previously discovered in 1868 in the chromosphere of the sun, by Jannsen, of Paris, and named helium by Frankland and Lockyer. Subsequent liquefaction of crude argon by means of liquid air, prepared by a process invented simultaneously by Linde and Hampson, gave a residue which was named by its discoverers, Ramsay and Travers, “neon.” Liquid argon has yielded two other gases also, “krypon” and “xenon.” These elements form a separate group in the Periodic Table, commencing with helium, with atomic weight, 4; neon, 20; argon, 40; krypon, 82; and xenon, 128. They all agree in being mono-atomic, _i.e._, their molecules consist of single atoms; and they have no tendency to form compounds, _i.e_., they possess no valency."}]}
{"messages": [{"role": "assistant", "content": "They all agree in being mono-atomic, _i.e._, their molecules consist of single atoms; and they have no tendency to form compounds, _i.e_., they possess no valency. In this sketch of the progress of chemistry during the century which has just passed, attention has been paid chiefly to the progress of thought. Allusions must, however, be made to the applications of chemistry to industrial purposes. The development of the soda industry, the preparation of carbonate of soda and caustic from common salt—initiated in France by LeBlanc (1742–1806)—has been developed by Tennant, in Scotland, and Muspeath and Gossage, and by Hargreaves, Weldon, and Maetea, in England; this process has at present a serious rival in the ammonia-soda process, developed by Solway, in Belgium, and by Brunner and Mond, in England. The main action of sulphuric acid, so long associated with the alkali process, has made enormous strides during the present century, but is still, in the main, the original process of causing sulphur dioxide in presence of water to absorb the oxygen of the air through nitric oxide. But the saving of the oxides of nitrogen through the invention of a sulphuric acid power by Gay-Lussac, known by his name, and the re-utilization of these oxides in the “Glover” power, invented by John Glover, of Newcastle, have greatly lessened the cost of the acid."}]}
{"messages": [{"role": "assistant", "content": "But the saving of the oxides of nitrogen through the invention of a sulphuric acid power by Gay-Lussac, known by his name, and the re-utilization of these oxides in the “Glover” power, invented by John Glover, of Newcastle, have greatly lessened the cost of the acid. Concentration of the acid in iron vessels is now common, the cost of platinum or of fragile glass vessels being thereby saved. The desulphurization of iron and the removal of silicon, carbon, and phosphorus by Bessemer’s process, modified by Thomas and Gilchrist through the introduction of a “basic magnesia lining” for the convertors, has made it possible to obtain pure iron and steel from ores previously regarded as of little value. The use of artificial manures, prepared by mixing refuse animal matters with tetra-hydrogen, calcium phosphate, and nitrate of soda, or sulphate of ammonia, first introduced by Liebig, has created a revolution in agricultural methods and in the weight of crops obtainable from a given area of soil. The influence of manures on crops has been fully studied by Lawes and Gilbert for more than fifty years in their experimental farm at Rothampstead. The most remarkable advances which have been made, however, are due to cheap electric current."}]}
{"messages": [{"role": "assistant", "content": "The most remarkable advances which have been made, however, are due to cheap electric current. The electrolysis of alumina, dissolved in fused cryolite to obtain aluminum, an operation carried out at Schaffhausen-on-the-Rhine, and at the Falls of Foyers, in Scotland; the electro-deposition of pure copper for electric wires and cables, electro-silvering, gilding, and nickelling, all these are instances where decomposition of a compound by the electric current has led to important industrial results. At present soda and chlorine are being manufactured by the electrolysis of salt solution contained in rocking trays, one of the electrodes being mercury, by the Castner-Kellner process. This manufacture is being carried on at Niagara, as well as in England. But electricity as a heating agent finds ever-extending application. Louis Moisson, professor at Paris, led the way by utilizing the enormous heat of the ore in his electric furnace, thereby, among other interesting reactions, manufacturing diamonds, small, it is true, though none the less real."}]}
{"messages": [{"role": "assistant", "content": "Louis Moisson, professor at Paris, led the way by utilizing the enormous heat of the ore in his electric furnace, thereby, among other interesting reactions, manufacturing diamonds, small, it is true, though none the less real. The use of electricity as a heating agent has received new applications. Phosphorus is now made by distilling a mixture of phosphates of lime and alumina with coke; a new polishing agent has been found in “carborundum,” a compound of carbon and silicon, produced by heating in an electric furnace a mixture of sand and coke; and cyanide of potassium, almost indispensable for the extraction of gold from ores poor in gold, is now manufactured by heating a mixture of carbon and carbonate of barium in an electric furnace in a current of carbon monoxide. These are but some of the instances in which electricity has been adopted as an agent in effecting chemical changes; and it may be confidently predicted that the earlier years of the twentieth century will witness a great development in this direction. It may be pointed out that the later developments of industrial chemistry owe their success entirely to the growth of chemical theory; and it is obvious that that nation which possesses the most competent chemists, theoretical and practical, is destined to succeed in the competition with other nations for commercial supremacy and all its concomitant advantages. WILLIAM RAMSAY."}]}
{"messages": [{"role": "assistant", "content": "WILLIAM RAMSAY. ARCHÆOLOGY \n\nTo write of the progress of archæology in this century is scarcely possible, as the idea of the subject was unknown a hundred years ago; it is, therefore, the whole history of its opening and development that we have to deal with. The conception of the history of man being preserved to us in material facts, and not only in written words, was quite disregarded until the growth of geology had taught men to read nature for themselves, instead of trusting to the interpretations formed by their ancestors. Even down to the present the academic view is that classical archæology is more important than other branches, because it serves to illustrate classical literature. Looked at as archæology, it is, on the contrary, the least important branch, because we already know so much more of the classical ages than we do of others. It is only within the present generation that it has been realized that wherever man has lived he has left the traces of his action, and that a systematic and observant study of those remains will interpret to us what his life was, what his abilities and tastes were, and the extent and nature of his mind."}]}
{"messages": [{"role": "assistant", "content": "It is only within the present generation that it has been realized that wherever man has lived he has left the traces of his action, and that a systematic and observant study of those remains will interpret to us what his life was, what his abilities and tastes were, and the extent and nature of his mind. Literature is but one branch of the archæology of the higher races; another—equally important for the understanding of man—is art; these two give the highest and most complex and characteristic view of the nature of a race. At the opposite end of the scale are the rudest stone weapons which remain as the sole traces of the savages who used them. These highest and lowest evidences of mind, and all that lies between them, are the domain of archæology. We now purpose to review the growth of archæology in contact with geology, where it concerns man as the last of the links of life on the globe; and then to notice the archæology of each country in turn, as it leads on to the times of historical record, and so passes down to modern times. A century ago the world of thought was divided between the old and new ideas very differently from what is now the case."}]}
{"messages": [{"role": "assistant", "content": "A century ago the world of thought was divided between the old and new ideas very differently from what is now the case. Then there stood on one side the idea of a special creation of an individual man, at 4000 B. C.; the compression of all human history into a prehistoric age of about three thousand years, and a fairly logical solution of most of the difficulties of understanding in a comfortable teleology. On the other hand stood many who felt the inherent improbability of such solutions of the problem of life, and who were feeling their way to some more workable theory on the basis of Laplace, Lamarck, Erasmus Darwin, and others; vaguely mingling together questions of physics, geology, archæology, anthropology, and theology, each of which we now see must be treated on its own basis, and be decided on internal evidence, before we can venture to let it affect our judgment on other points. The great new force which thrust itself in to divide and decide on these questions is the scientific study of man and his works. Strangely shaped flints had been noticed, but no one had any knowledge of their age."}]}
{"messages": [{"role": "assistant", "content": "Strangely shaped flints had been noticed, but no one had any knowledge of their age. One such, when found with the bones of a mammoth, was attributed to the Roman age, because no person could have brought elephants into Britain except some Roman general. The argument was excellent and irrefutable until geology found plenty more remains of the mammoth and showed that it was here long before the Romans. It was less than half a century ago that our eyes began to open to the abundant remains of flint-using man. Then a single rude stone weapon was an unexplained curiosity; now an active collector will put together his tens of thousands of specimens, will know exactly where they were found, their relation of age and of purpose, and their bearing on the history of man. Not only have worked flint implements been found in the river gravels of France and England, where they were first noticed in the middle of this century, but also in most parts of Europe, in Egypt on the high desert, in Somaliland, at the Cape of Good Hope, in India, America, and other countries; and the most striking feature is the exact similarity in form wherever they have been found."}]}
{"messages": [{"role": "assistant", "content": "Not only have worked flint implements been found in the river gravels of France and England, where they were first noticed in the middle of this century, but also in most parts of Europe, in Egypt on the high desert, in Somaliland, at the Cape of Good Hope, in India, America, and other countries; and the most striking feature is the exact similarity in form wherever they have been found. So precisely do the same types recur, so impossible would it be to say from its form whether a flint had been found in Europe, Asia, or Africa, that it appears as if the art of working had spread from some single centre over the rest of the world. This is especially the case with the river-gravel flints—the earlier class—usually called Paleolithic. Soon after the general division had been made between polished stone-work of the later or Neolithic times, found on the surface, and the rough chipped work of the earlier or Paleolithic times, found in geological deposits, a further sub-division was made by separating the Paleolithic age into that of the river gravels and that of the cave-dwellers. The latter has again been divided into three classes by French writers, named, from their localities, _Mousterien_, _Solutrien_, _Magdalenien_; and, though these classes may be much influenced by locality, they probably have some difference of age between them. And now within the last few years a still earlier kind of workmanship has been recognized in flints found in England on the high hills in Kent."}]}
{"messages": [{"role": "assistant", "content": "And now within the last few years a still earlier kind of workmanship has been recognized in flints found in England on the high hills in Kent. Though at first much disputed, the human origin of the forms is now generally acknowledged, and they show a far ruder ability than even the most massive of the Paleolithic forms. The position also of these flints, in river deposits lying on the highest hills some six hundred feet above the present rivers, shows that the whole of the valleys has been excavated since they were deposited, and implies a far greater age than any of the gravel beds of the Paleolithic ages. We, therefore, have passed now at the beginning of this century to a far wider view of man’s history, and classify his earlier ages in Europe thus: \n    First—Eolithic: Rudest massive flints from deposits 600 feet up. Second—Paleolithic: Massive flints from gravels 200 feet up and     less (Achuleen). Third—Paleolithic—Cave-dwellers: Flints like the preceding and     flakes (Mousterien)."}]}
{"messages": [{"role": "assistant", "content": "Third—Paleolithic—Cave-dwellers: Flints like the preceding and     flakes (Mousterien). Fourth—Paleolithic—Cave-dwellers: Flints well worked and finely     shaped (Solutrien). Fifth—Paleolithic—Cave-dwellers: Abundant bone working and     drawing (Magdalenien). Sixth—Neolithic: Polished flint working, pastoral and     agricultural man. What time these periods cover nothing yet proves. The date of 4000 B."}]}
{"messages": [{"role": "assistant", "content": "The date of 4000 B. C. for man’s appearance, with which belief the nineteenth century started, has been pushed back by one discovery after another. Estimates of from 10,000 to 200,000 years have been given from various possible clews. In Egypt an exposure of 7000 years or more only gives a faint brown tint to flints lying side by side with Paleolithic flints that are black with age. I incline to think that 100,000 years B."}]}
{"messages": [{"role": "assistant", "content": "I incline to think that 100,000 years B. C. for the rise of the second class, and 10,000 B. C. for the rise of the sixth class will be a moderate estimate. Passing now from Paleolithic man of the latest geological times whose works lie under the deposit of ages, to Neolithic man of surface history whose polished stone tools lie on the ground, we find also how greatly views have changed."}]}
{"messages": [{"role": "assistant", "content": "Passing now from Paleolithic man of the latest geological times whose works lie under the deposit of ages, to Neolithic man of surface history whose polished stone tools lie on the ground, we find also how greatly views have changed. For ages past metal-using man has looked on the beautifully polished or chipped weapons of his forefathers as “thunderbolts,” possessing magic powers, and he often mounted the smaller ones to wear as charms. At the beginning of this century well-finished stone weapons were only preserved as curiosities which might belong to some remote age, but without any definite ideas about them. The recognition of long ages of earlier unpolished stone work has now put these more elaborate specimens to a comparatively late period, and yet they are probably older than the date to which our forefathers placed the creation of man. The beginning of a more intelligent knowledge of such things was laid by the systematic excavations of the burial mounds scattered over the south of England, which was done in the early part of this century by Sir Richard Colt Hoare. A solid basis of facts was laid, which began to supersede the romances woven by Stukeley and others in the last century."}]}
{"messages": [{"role": "assistant", "content": "A solid basis of facts was laid, which began to supersede the romances woven by Stukeley and others in the last century. Gradually more exact methods of search were introduced, and in the last thirty years Canon Greenwell has done much, and General Pitt Rivers has established a standard of accurate and complete work with perfect recording, which is the highest development of archæological study. These and other researches have opened up the life of Neolithic man to us, and we see that he was much as modern man, if compared with the earlier stage of man as a hunter. The Neolithic man made pottery, spun and wove linen, constructed enormous earthworks both for defence and for burial, and systematically made his tools of the best material he could obtain by combined labor in mining. The extensive flint-mines in chalk districts of England show long-continued labor; and the perfect form and splendid finish of many of the stone weapons show that skilled leisure could be devoted to them, and that æsthetic taste had been developed. The large camps prove that a thorough tribal organization prevailed, though probably confined to small clans."}]}
{"messages": [{"role": "assistant", "content": "The large camps prove that a thorough tribal organization prevailed, though probably confined to small clans. About the middle of the century a new type of dwelling began to be explored—the lake dwelling; this system of building towns upon piles in lakes had the great advantage of protection from enemies and wild beasts, and a constant supply of food in the fish that could be hooked from the water below. Though such settlements were first found in the Swiss lakes, and explored there by Keller, they have since been found in France, Hungary, Italy, Holland, and the British Isles. The earlier settlements of this form belong to the Neolithic age, but only in central Europe. In these earliest lake dwellings weaving was known, and the cultivation of flax, grapes, and other fruit and corn; while the usual domestic animals were kept and cattle were yoked to the plough; pottery was abundant, and was often ornamented with geometric patterns. The type of man was round-headed."}]}
{"messages": [{"role": "assistant", "content": "The type of man was round-headed. Following the Neolithic lake dwellings came those of the Bronze age, and as the bronze objects are similar to those found in other kinds of dwellings we shall notice them in the Bronze age in general. The type of man was longer-headed than in the earlier lake settlement. The domestication of animals shows an advance; the horse was common, and the dog, ox, pig, and sheep were greatly improved. Pottery was better made and elaborately decorated, often with strips of tin-foil. The Bronze age marks a great step in man’s history."}]}
{"messages": [{"role": "assistant", "content": "The Bronze age marks a great step in man’s history. In many countries the use of copper, hardened by arsenic or oxide, was common for long before the alloy of copper and tin was used. In other countries, where the use of metals was imported, copper only appears as a native imitation of the imported bronze. Hence there is a true age of copper in lands where the use of metals has grown. It must by no means be supposed that copper excluded the use of flint; it was not until bronze became common that flint was disused. The existence of a Bronze age was first formulated, as distinct from a Stone age, about seventy years ago; and the existence of a Copper age has been much disputed in the last thirty years, but has only been proved clearly ten years ago, in Egypt."}]}
{"messages": [{"role": "assistant", "content": "The existence of a Bronze age was first formulated, as distinct from a Stone age, about seventy years ago; and the existence of a Copper age has been much disputed in the last thirty years, but has only been proved clearly ten years ago, in Egypt. In the eighteenth century the bronze weapons found in England were attributed to the Romans by some writers, though others, with more reason, argued that they were British. In the first year of the century began the comparative study of such weapons with reference to modern savage products. The development of the metal forms from stone prototypes was pointed out in 1816; the tracing out of the succession of the forms and the modes of use appeared in 1847. Further study cleared up the details, and within the last twenty years the full knowledge of the Bronze age in other countries has left no question as to the general facts of the sequence of its history. In each type of tool and weapon there appears first a very simple form imitated from the stone implements which were earlier used."}]}
{"messages": [{"role": "assistant", "content": "In each type of tool and weapon there appears first a very simple form imitated from the stone implements which were earlier used. Gradually the facilities given by the casting and toughness of the metal were used, and the forms were modified; ornamentation was added, and thin work in embossed patterns gave the stiffness and strength which had been attained before by massive forms. The general types are the axe—first a plain slip of metal, later developed with a socket; then the chisel, gouge, sickle, knife, dagger, sword, spear, and shield; personal objects, as pins, necklets, bracelets, ear-rings, buttons, buckles, and domestic caldrons and cups. Most of these forms were found together, all worn out and broken, in the great bronze-founder’s hoard at Bologna. Lastly in the prehistory of Europe comes the Iron age, which so much belongs to the historical period that we can best consider it in noticing separate countries. From the recent discoveries in Egypt we can gain some idea of the date of these periods."}]}
{"messages": [{"role": "assistant", "content": "From the recent discoveries in Egypt we can gain some idea of the date of these periods. We ventured to assign about 10,000 B. C. for the rise of the Neolithic or polished-stone period (it may very possibly be earlier); the beginning of the use of copper may be placed about 5000 B. C.; the beginning of bronze was perhaps 3000 or 2000 B. C., as its free use in Egypt is not till 1600 B."}]}
{"messages": [{"role": "assistant", "content": "C., as its free use in Egypt is not till 1600 B. C.; and the use of iron beginning about 1000 B. C., probably in Armenia, spreading thence through Europe until it reached Italy, perhaps 700 years B. C., and Britain about 400 B. C. Such is the briefest outline of the greater part of the history of man, massed together in one general term of “prehistoric,” before we reach the little fringe of history nearest to our own age."}]}
{"messages": [{"role": "assistant", "content": "Such is the briefest outline of the greater part of the history of man, massed together in one general term of “prehistoric,” before we reach the little fringe of history nearest to our own age. The whole of this knowledge results from the work of the century. We now turn to the historical ages of each of the principal countries, to review what advance has been made even where a basis of written record has come down to us, equally accessible in all recent times. EGYPT \nAt the beginning of the century Egypt was a land of untouched and inexplicable mystery; the hieroglyphics were wondered at, and puzzled over, without any idea of how they were to be read, whether as symbols or as letters. The history was entirely derived from the confused accounts of Greek authors, the lists remaining of Manetho’s history, written about 260 B. C., and the allusions in the Bible."}]}
{"messages": [{"role": "assistant", "content": "C., and the allusions in the Bible. The attempt to make everything fit to the ideas of the Greeks, and to make everything refer to the Biblical history, greatly retarded the understanding of the monuments, and is scarcely overcome yet. The first great step forward was when an inscription was found at Rosetta, in 1799, written in two methods, the monumental hieroglyphic and the popular demotic, along with a Greek version. By 1802 some groups of each writing had been translated. Young identified more signs, and Gell, by 1822, could successfully apportion three-quarters of the signs to the Greek words. The next step was to apply the modern Coptic language, descended from the ancient Egyptian, to the reading of the words."}]}
{"messages": [{"role": "assistant", "content": "The next step was to apply the modern Coptic language, descended from the ancient Egyptian, to the reading of the words. Gell had been doing so, but it needed a student of Coptic—Champollion—to carry this out thoroughly, as he did in 1821–32. Since then advance in reading has been only a matter of detail, not requiring any new principles. The knowledge of the art began with the admiration for the debased work of Roman times, the principal interest at the beginning of the century. Then the excavations among the Rameside monuments at Thebes, about 1820–30, took attention back to the age of 1500–1000 B. C."}]}
{"messages": [{"role": "assistant", "content": "C. The work of Lepsius, and later of Mariette, from 1840–80, opened men’s eyes to the splendid work of the early dynasties, about 4000–3000 B. C. And lastly the excavations of 1893–99 have fascinated scholars by a view of the rise of the civilization and the prehistoric period before 5000 B. C. Throughout the greater part of the century the archæology of Egypt lay untouched; all attention was given to the language; and even Gardner Wilkinson’s fine view of the civilization (1837) depended largely on Greek authors, and had no perspective of history in tracing changes and development."}]}
{"messages": [{"role": "assistant", "content": "Throughout the greater part of the century the archæology of Egypt lay untouched; all attention was given to the language; and even Gardner Wilkinson’s fine view of the civilization (1837) depended largely on Greek authors, and had no perspective of history in tracing changes and development. It is only in the last ten or fifteen years that any exact knowledge has been acquired about the rise and progress of the various arts of life; this study now enables us to date the sculpture, metal work, pottery, and other art products as exactly as we can those of the Middle Ages. The view that we now have of the rise and decay of this great civilization and its connection with other lands is more complete and far-reaching than that of any other country. In the early undated age, before the monarchy which began about 4800 B. C., a flourishing civilization was spread over upper Egypt. Towns were built of brick, as in later times; clothing was made of woven linen and of leather; pottery was most skilfully formed, without the potter’s wheel, hand-made, yet of exquisite regularity and beauty of outline, while the variety of form is perhaps greater than in any other land; stone vases were made entirely by hand, without a lathe, as perfect in form as the pottery, and of the hardest rocks, as diorite and granite; wood was carved for furniture; the art of colored glazing was common, and was even applied to glazing over large carvings in rock crystal; ornaments and beads were wrought of various stones and precious metals; ivory combs with carved figures adorned the hair; ivory spoons were used at the table; finely formed weapons and tools of copper served where strength was needful, while more useful were flint knives and lances which were wrought with a miraculous finish that has never been reached by any other people; and games were played with dainty pieces made of hard stone and of ivory."}]}
{"messages": [{"role": "assistant", "content": "Towns were built of brick, as in later times; clothing was made of woven linen and of leather; pottery was most skilfully formed, without the potter’s wheel, hand-made, yet of exquisite regularity and beauty of outline, while the variety of form is perhaps greater than in any other land; stone vases were made entirely by hand, without a lathe, as perfect in form as the pottery, and of the hardest rocks, as diorite and granite; wood was carved for furniture; the art of colored glazing was common, and was even applied to glazing over large carvings in rock crystal; ornaments and beads were wrought of various stones and precious metals; ivory combs with carved figures adorned the hair; ivory spoons were used at the table; finely formed weapons and tools of copper served where strength was needful, while more useful were flint knives and lances which were wrought with a miraculous finish that has never been reached by any other people; and games were played with dainty pieces made of hard stone and of ivory. But all this tasteful skill of 6000–5000 B. C. had its negative side; in the artistic copying of nature the mechanical skill of these people carried them a very little way; their figures and heads of men and animals are strangely crude. And they had no system of writing, although marks were commonly used. They always buried the body doubled up, and often preserved the head and hands separately."}]}
{"messages": [{"role": "assistant", "content": "They always buried the body doubled up, and often preserved the head and hands separately. Commerce was already active, and large rowing-galleys carried the wares of different countries around the Mediterranean. These people were the same as the modern Kabyle, of Algeria, and akin to the South European races, but with some negro admixture. Our whole knowledge of this age has only been gained within the last five years. At about 5000 B. C."}]}
{"messages": [{"role": "assistant", "content": "C. there poured into Egypt a very different people, probably from the Red Sea. Having far more artistic taste, a commoner use of metals, a system of writing already begun, and a more organized government, these fresh people started a new civilization in Egypt; adopting readily the art and skill of the earlier race, they formed by their union the peculiar culture known as Egyptian, a type which lasted for four thousand years. The same foundation of a type is seen in the bodily structure; the early historical people had wider heads and more slender noses than the prehistoric, but from 4000 B. C. down to Roman times the form shows no change."}]}
{"messages": [{"role": "assistant", "content": "down to Roman times the form shows no change. From this union of two able races came one of the finest peoples ever seen, the Egyptians of the old kingdom, 4500—3500 B. C. Full of grand conceptions, active, able, highly mechanical, and yet splendid artists, they have left behind them the greatest masses of building, the most accurate workmanship and exquisite sculptures in the grand pyramids and tombs of their cemeteries. They perfected the art of organizing combined labor on the immense public works. In all these respects no later age or country has advanced beyond this early ability."}]}
{"messages": [{"role": "assistant", "content": "In all these respects no later age or country has advanced beyond this early ability. The moral character and ideas are preserved to us in the writings of these people; and we there read of the ability, reserve, steadfastness, and kindliness which we see reflected in the lifelike portraiture of that age. After a partial decay about 3000 B. C. this civilization blossomed out again nobly in the twelfth dynasty about 2600 B. C.; though the works of this age hardly reach the high level of the earlier times, yet they are finer than anything that followed them."}]}
{"messages": [{"role": "assistant", "content": "C.; though the works of this age hardly reach the high level of the earlier times, yet they are finer than anything that followed them. At this period more contact with other countries is seen; both Syria and the Mediterranean were known, though imperfectly. To this succeeded another decadence, sealed by the disaster of the foreign invasion of the Hyksos. But this was thrown off by the rise of a third age of brilliance—the eighteenth dynasty, 1500 B. C.—which, though inferior to early times in its highest work, yet shines by the widespread of art and luxury throughout the upper classes. Magnificence became fashionable, and the lower classes contented themselves with most barefaced imitations of costly wares."}]}
{"messages": [{"role": "assistant", "content": "Magnificence became fashionable, and the lower classes contented themselves with most barefaced imitations of costly wares. Foreign islands came closely in contact with Egypt. The ships of the Syrian coast and Cyprus continually traded to and fro, exchanging silver, copper, and precious stones for the gold of Egypt. Greece also traded its fine pottery of the Mycenæan age for the showy necklaces of gold and the rings and amulets with names of Pharaohs. Egypt then dominated the shores of the western Mediterranean, the plains of the Euphrates, and the fertile Soudan. But this power and wealth led to disaster."}]}
{"messages": [{"role": "assistant", "content": "But this power and wealth led to disaster. Like Rome, later on, she could not resist the temptation to live on plunder; heavy tribute of corn was exacted, large numbers were employed in unproductive labor, and national disaster was the natural consequence. Egypt never recovered the dominion or the splendor that were hers in this age. Of this period some slight notions are given us from literary remains in the Bible and Greek authors; but archæology is, so far, our only practical guide, as in the earlier ages. The great temples and monuments of the eighteenth-twentieth dynasties (1600–1100 B. C.) bear hundreds of historical inscriptions, the tombs are covered with scenes of private life, the burials and the ruins of towns furnish us with all the objects of daily use."}]}
{"messages": [{"role": "assistant", "content": "C.) bear hundreds of historical inscriptions, the tombs are covered with scenes of private life, the burials and the ruins of towns furnish us with all the objects of daily use. This age is one of the fullest and richest in all history, and hardly any other is better known even in Greece or Italy. Yet all this has been brought to light in the century, and the knowledge of the foreign relations of Egypt is entirely the result of the last fifteen years. The final thousand years of the civilization of Egypt is checkered with many changes; sometimes independent, as in the ages of Shishak of Necho, and of the Ptolemies; at other times a prey to Ethiopians, Persians, Greeks, or Romans. Its arts and crafts show a constant decay, and there was but little left to resist the influence of Greek taste and design, which ran a debased course in the country. There was, however, a spread of manufactures and of cheap luxuries into lower and lower classes; and the wealth of the country accumulated under the beneficent rule of the earlier Ptolemies (300–200 B."}]}
{"messages": [{"role": "assistant", "content": "There was, however, a spread of manufactures and of cheap luxuries into lower and lower classes; and the wealth of the country accumulated under the beneficent rule of the earlier Ptolemies (300–200 B. C.). The principal discoveries about these later ages have been in the papyri, which have been largely found during the last twenty years. The details of the government and life of the country in the Ptolemaic (305–30 B. C.) and Roman (30 B. C.–640 A."}]}
{"messages": [{"role": "assistant", "content": "C.–640 A. D.) periods have been cleared up; and many prizes of classical literature have also been recovered. The archæology of the Middle Ages in Egypt has also been studied. Many of the Arabic buildings have been recently cleaned and put in good condition, and the splendid collection of manuscripts in Cairo has opened a view of the beautiful art of the thirteenth-fifteenth centuries so closely akin to what was done in Europe at the same time. Egypt is, then, before all other lands, the country of archæology. A continuous history of seven thousand years, with abundant remains of every period to illustrate it, and a rich prehistoric age before that, give completeness to the study and the fullest value to archæological research."}]}
{"messages": [{"role": "assistant", "content": "A continuous history of seven thousand years, with abundant remains of every period to illustrate it, and a rich prehistoric age before that, give completeness to the study and the fullest value to archæological research. MESOPOTAMIA \nThe valley of the Euphrates might well rival that of the Nile if it were scientifically explored, but unhappily all the excavation has been done solely with a view to inscription and sculpture, and no proper record has been made, nor have any towns been examined, the only work being in palaces and temples. The earliest study on the ground was by Rich (1818–20), who gathered some few sculptures and formed an idea of Assyrian art. The French Consul, Botta, excavated Khorsabad (founded 700 B. C.) in 1834–35, and Layard excavated Nimrud in 1845–47; these were both Assyrian sites. The older Babylonian civilization was touched at Erech by Loftus, in 1849–52; and this age has attracted the most important excavations made since, at Tello by Sarzec (1876–81), and at Nippur by Peters and Haynes, of Philadelphia, during the last few years."}]}
{"messages": [{"role": "assistant", "content": "The older Babylonian civilization was touched at Erech by Loftus, in 1849–52; and this age has attracted the most important excavations made since, at Tello by Sarzec (1876–81), and at Nippur by Peters and Haynes, of Philadelphia, during the last few years. The cuneiform characters were absolutely unexplained until Grotefend, in 1800, resolved several of them by taking inscriptions which he presumed might contain names of Persian kings and comparing them alongside of the known names; thus—without a single fixed point to start from—he tried a series of hypotheses until he found one which fitted the facts. Bournouf (in 1836) and Lassen (1836–44) rectified and completed the alphabet. But the cuneiform signs were used to write many diverse languages, as the Roman alphabet is used at present; and the short Persian alphabet was only a fraction of the great syllabary of six hundred signs used for Assyrian. Rawlinson had independently made out the Persian alphabet, using the Zend and Sanskrit for the language. He next, from the trilingual Behistun inscription in Persian, Assyrian, and Vannic, resolved the long Assyrian syllabary, using Hebrew for the language."}]}
{"messages": [{"role": "assistant", "content": "He next, from the trilingual Behistun inscription in Persian, Assyrian, and Vannic, resolved the long Assyrian syllabary, using Hebrew for the language. Since then other more obscure languages written in cuneiform have been worked with more or less success; the most important is the Turanian language, used by the earlier inhabitants of Babylonia before the Semitic invasion; this is recorded by many syllabaries and dictionaries, and translations compiled by the literary Semitic kings. The general view of the civilization which has been obtained by these labors of the century shows it to have been more important to the world than any other. Cuneiform was the literary script of the world for at least six thousand years, the only medium of writing from the Mediterranean to the Indian Ocean. The Babylonian culture was almost certainly the source of the oldest present civilization—that of China. And the arts were developed probably even earlier than in Egypt."}]}
{"messages": [{"role": "assistant", "content": "And the arts were developed probably even earlier than in Egypt. The first inhabitants were called Sumirian (or river folk) in distinction from the Accadian (or highland) people, who came from Elam down into the Euphrates valley, bringing with them the use of writing. Their earliest writing was of figure symbols (like the Egyptian and Hittite); but as in the valley clay tablets were the only material for writing, the figures became gradually transformed into groups of straight lines and spots impressed on the clay; hence the signs were formalized into what we call cuneiform. The Semitic invaders were using cuneiform characters by about 3000 B. C. The early civilization was intensely religious, the main buildings being the temples, which were placed on enormous piles of brick-work."}]}
{"messages": [{"role": "assistant", "content": "The early civilization was intensely religious, the main buildings being the temples, which were placed on enormous piles of brick-work. The sculpture was at a high level in the time of Naram-Sinn, about 3750 B. C.; and yet below his ruins at Nippur there are no less than thirty-five feet depth of earlier ruins, which must extend back to 6000 or 7000 B. C. In early times stone implements were used alongside of copper and bronze, as we find in Egypt 4000 B. C."}]}
{"messages": [{"role": "assistant", "content": "C. Pottery was well made, and also reliefs in terra-cotta. Personal ornaments of engraved gems and gold-work were common. The main landmarks in the later time of this civilization are the Elamite invasion of Kudur-nan-khundi (2280 B. C.) which upset the Semitic rulers, and the Assyrian invasion of Tiglath-Adar (1270 B. C.), after which interest centres in the Assyrian kingdom and its development of the Mesopotamian culture which it borrowed."}]}
{"messages": [{"role": "assistant", "content": "C.), after which interest centres in the Assyrian kingdom and its development of the Mesopotamian culture which it borrowed. The main buildings of the Assyrian kings were their enormous palaces, the mass of which was of unbaked bricks, faced with alabaster slabs; such were the works of Assurnazir-pal (Nimrud, 880 B. C.), Sargon (Khorsabad, 710 B. C.), Sennacherib and Assurbani-pal (Kouyunjik, 700 B. C.). The later, Assyrian, form of the civilization was to the earlier Chaldean much what Rome was to Greece, a rather clumsy borrower, who laboriously preserved the literature and art."}]}
{"messages": [{"role": "assistant", "content": "The later, Assyrian, form of the civilization was to the earlier Chaldean much what Rome was to Greece, a rather clumsy borrower, who laboriously preserved the literature and art. Some of the Assyrian sculpture of animals is, however, perhaps unsurpassed for vivid action. The systematic libraries, containing copies of all the older literature for general study, were most creditable, though the Assyrian himself composed nothing better than chronicles. Nearly all that we possess of Babylonian religion, and much of the history, is in the copies scrupulously made from the ancient tablets by the Assyrian scribes, who noted every defect in the original with critical fidelity. The Mesopotamian civilization has left its mark on the modern world. Its religion greatly influenced Hebrew, and thence Christian, thought, the psalms, for instance, being a Babylonian form of piety."}]}
{"messages": [{"role": "assistant", "content": "Its religion greatly influenced Hebrew, and thence Christian, thought, the psalms, for instance, being a Babylonian form of piety. Its science fixed the signs of the zodiac, the months of the year, the days of the week, and the division of the circle in degrees, all of which are now universal. And its art, carried by the Phœnicians, was copied by the Greeks and Etruscans, and thus passed on into modern design. SYRIA \nThe knowledge of Palestine was but slight, and of northern Syria nothing to speak of, a century ago. Travellers with some scientific ability, such as Robinson (1838 and 1852), De Saulcy (1853), and Van de Velde (1854), greatly extended our view and led up to the splendid survey by the Palestine Exploration Fund (1866 and on), which exhausted the surface study of the land. The more archæological work of excavation was begun at Jerusalem (1867–70), and resumed (1892–99) at Lachish, Jerusalem, etc."}]}
{"messages": [{"role": "assistant", "content": "The more archæological work of excavation was begun at Jerusalem (1867–70), and resumed (1892–99) at Lachish, Jerusalem, etc. The topographical results are all important, and leave nothing to be done until excavation can be freely applied; and the small amount of digging yet done has fixed the varieties of pottery back to 2000 B. C. and given some early architecture. But the ruins of Syria, and indeed of Turkey in general, are practically yet untouched. The discovery (1868) of the inscription of Mesha, King of Moab (896 B."}]}
{"messages": [{"role": "assistant", "content": "The discovery (1868) of the inscription of Mesha, King of Moab (896 B. C.), opened a new prospect of research which cannot yet be entered upon. In the north of Syria nothing has been done except the German work at Singerli, from which came an Aramean inscription of about 740 B. C. And in the south a large number of early inscriptions of the Arabian dynasties, reaching back some centuries B. C., have been copied; but there, also, excavation is impossible."}]}
{"messages": [{"role": "assistant", "content": "C., have been copied; but there, also, excavation is impossible. The main new light from Syria has been on the Hittite power. Burckhardt, in 1812, had noticed a new kind of hieroglyph at Hamath. After several ineffective copies, Wright made casts of the stones in 1872. Several other such inscriptions have been found, and from these and the Egyptian and Assyrian references to the Hittites we now realize that they were a northern people, with a great capital on the Euphrates, at Karkhemish, and ruling over nearly all Syria and Asia Minor. Little has yet been fixed about the writing; a few signs are read and some have passed into the Cypriote alphabet."}]}
{"messages": [{"role": "assistant", "content": "Little has yet been fixed about the writing; a few signs are read and some have passed into the Cypriote alphabet. A striking proof of the spread of Babylonian culture is seen in the tablets found in Egypt at Tel-el-Amarna in 1887, which show that all the correspondence between Egypt and Syria in the fifteenth century B. C. was carried on in cuneiform. These hundreds of letters give a vivid picture of life in Syria at that early date. GREECE \nThe revival of interest in Greek civilization was at first purely literary, and remained so during two or three centuries."}]}
{"messages": [{"role": "assistant", "content": "GREECE \nThe revival of interest in Greek civilization was at first purely literary, and remained so during two or three centuries. But during the last century various travellers and residents abroad made collections which awoke an interest in the art; and though most of these collectors were content with merely showy sculpture, greatly restored and falsified for the market, yet some—such as Hamilton—took a real archæological interest in the unearthing and collecting of ancient art. The condition of study at the end of the eighteenth century was that many private men of wealth had bought large quantities of sculpture which was but little understood, and looked on more from a decorative than a scientific point of view, while there were the beginnings of a serious appreciation of it which had been just laid down by Winckelmann. The nineteenth century opened with a grand work of publishing the principal treasures of classical art in England, which was finally issued in 1809 by Payne, Knight, and Townley; this marks the highest point of the dilettante collecting spirit, which was soon eclipsed by truer knowledge. Hitherto the best sculpture had hardly been known but at second hand through Roman copies; a closer acquaintance began with the travels of Dodwell, Gell, and Leake, all in the first decade of the century. The free opening of the British Museum, in 1805, and the accumulation there of all the best collections within the first quarter of the century, also served to educate a public taste."}]}
{"messages": [{"role": "assistant", "content": "The free opening of the British Museum, in 1805, and the accumulation there of all the best collections within the first quarter of the century, also served to educate a public taste. The first struggle of scientific and artistic knowledge against the dilettante spirit was over the Elgin marbles; by 1816 they were accepted as the masterpieces which all later criticism has proved them to be. The Æginetan and Phigaleian sculptures, brought to Munich and London, helped also to show the nobility of early Greek art; so that the last two generations have had a canon of taste to rely upon, the value of which cannot be overestimated. Following on this noble foundation, other collectors worked in Greece and Asia Minor, and the British Museum profited by the labors of Burgon, Fellows, and Woodhouse between 1840 and 1860. The diplomatically supported work of Newton on the Mausoleum (1857–58), and Wood at Ephesus (1863–75), filled out our knowledge of the middle period of Greek art (350 B. C.)."}]}
{"messages": [{"role": "assistant", "content": "C.). Comparatively little has been done since then by England, but the activity of the Germans at Olympia has given us the only original masterpiece that is known—the Hermes of Praxiteles (350 B. C.), and their work at Pergamon revealed the great altar belonging to the later age (180 B. C.). The excavations at Athens (in 1886) have produced the impressive statues dedicated to Athene about 520 B. C., which reveal the noble rise of Attic sculpture."}]}
{"messages": [{"role": "assistant", "content": "C., which reveal the noble rise of Attic sculpture. But attention during the last quarter-century has been largely fixed upon the earlier ages. The discoveries of Schliemann at Hissarlik (Troy, 1870–82), Mycenæ (1876), Orchomenos (1880–81), and Tiryns (1884), opened a new world of thought and research. Though at first bitterly attacked, it is now agreed that these discoveries show us the civilization of Greece between 2000 and 1000 B. C. Lastly, during ten years past Egypt has provided the solid chronology for prehistoric Greece by discoveries of trade between the two countries."}]}
{"messages": [{"role": "assistant", "content": "Lastly, during ten years past Egypt has provided the solid chronology for prehistoric Greece by discoveries of trade between the two countries. We can now very briefly estimate the present position of our knowledge as gained during the century. Setting aside the early foreign pottery found in Egypt, which belongs probably to Greece or Italy at 5000 and 3000 B. C., we first touch a civilized city in the lowest town of Troy, where metal was scarcely yet in use, which is certainly before 2000 and probably about 3000 B. C. in date."}]}
{"messages": [{"role": "assistant", "content": "in date. Succeeding that is the finely built second Troy, rich in gold vases and ornaments, which—though mistaken by Schliemann for the Homeric Troy—must yet be long before that, probably before 2000 B. C. After the burning of that come three other rebuildings before we reach the town of the age of Mycenæ, about 1500 B. C. Of this, which was in Greece the climax of the prehistoric civilization, there are the splendid treasures found at Mycenæ, the magnificent domed tombs, the abundance of fine jewelry and metal-work, of beautiful pottery and glazed ornament."}]}
{"messages": [{"role": "assistant", "content": "Of this, which was in Greece the climax of the prehistoric civilization, there are the splendid treasures found at Mycenæ, the magnificent domed tombs, the abundance of fine jewelry and metal-work, of beautiful pottery and glazed ornament. To this age belong the great palaces of Mycenæ, Tiryns, Athens, and other hill fortresses, of which hardly more than the plans can now be traced. And it is this civilization which traded eagerly with Egypt, exchanging the valued manufactures of each country. This period was at its full bloom from 1500–1200 B. C., and began to decay by 1100 B. C., this dating being given by the contact with Egypt."}]}
{"messages": [{"role": "assistant", "content": "C., this dating being given by the contact with Egypt. This natural decadence of art in Greece was hastened by the invasion of the barbarous Dorians about 1000 B. C. Art, however, was by no means extinguished, but only repressed by the troubles of the age; and Athens, which was not conquered by the Dorians, was the main centre of the revival of the arts. Other examples of such a history are familiar in Egypt (after the Hyksos invasion) and in Italy (after the Lombards), where earlier abilities revive and bloom afresh when vigorous invaders become united to an artistic stock. After the centuries of warfare a quieter age allowed the growth of fine arts again in the seventh century B."}]}
{"messages": [{"role": "assistant", "content": "After the centuries of warfare a quieter age allowed the growth of fine arts again in the seventh century B. C., largely influenced by Egyptian and Assyrian work at second hand, through the Greek settlements in Cyprus and Egypt. By 600 B. C. definite types of sculpture were started, and a course was begun which only ended in the fall of classical civilization. The century before the Persian invasion, in 480 B."}]}
{"messages": [{"role": "assistant", "content": "The century before the Persian invasion, in 480 B. C., was one of rapid development; and in sculpture and vase-painting we see that this century carried forward the arts to technical perfection and the highest power of expression. Immediately after the Persian wars came the supreme works of Pheidias and Myron, most familiar in the Parthenon and the Discobolus; and in vase-painting comes the reversal from vases drawn in black on a red ground to the blocking out of the ground in black, leaving the figure in red, thus giving far greater scope to the filling in of finely drawn detail. The civilization of Athens was also at its height in this age, under Pericles, and the minor arts received their most refined and perfect treatment. After this comes nothing but ripening to decay. It must always be remembered that we have but very few examples of original work of the great artists."}]}
{"messages": [{"role": "assistant", "content": "It must always be remembered that we have but very few examples of original work of the great artists. Nearly all the actual marbles preserved are copies made in later times, which show little of the delicacy of the original; and the few original marbles that remain are mostly of unknown subjects by unknown men. The great work in Greek archæology during the last fifty years has been comparing the records of ancient art (in Pliny, Pausanias, etc.) with the remaining sculptures, critically assigning the various types of statues to their celebrated originals, and thus forming some idea of the real history of Greek art. From these studies, full of detail and controversy, we may briefly sum up the characteristics of the principal artists and their imitators. At about 440 B. C."}]}
{"messages": [{"role": "assistant", "content": "C. Pheidias showed in the Parthenon the highest expression of divine and mythic forms, in a simple and heroic style which was never equalled. Half a century later Polykleitos followed a more human expression, using motives (as in the Doryphoros), but yet portraying an abstract humanity. By 330 B. C. Praxiteles brought the expression of moods to his works, graceful, animated, and with a full ripeness, as in the Hermes of Olympia, or the Faun."}]}
{"messages": [{"role": "assistant", "content": "Praxiteles brought the expression of moods to his works, graceful, animated, and with a full ripeness, as in the Hermes of Olympia, or the Faun. Skopas, slightly later, marked his work by his great vigor and strong personality. This was the second turning-point, when ripeness passed into decay; and in Lysippos there is mere vivid naturalism and an impressionist manner without much soul or thought, as in his Apoxyomenos, about 330 B. C. After this mere triviality and genre subjects are usual, portraiture is a common aim, and dignity was vainly striven for in colossal size. The glorification of showing dead and vanquished enemies is seen in the Dying Gaul and figures of slain foes at Pergamon."}]}
{"messages": [{"role": "assistant", "content": "The glorification of showing dead and vanquished enemies is seen in the Dying Gaul and figures of slain foes at Pergamon. Later on, about 180 B. C., we see the violent, complicated, and straining action of the figures around the great altar of Pergamon, which also appears in the groups of the Laocoon and Farnese Bull. In the Græco-Roman age a conscious artificiality took the place of life and expression, as we see in the Apollo Belvidere, the Venus di Medici, and the Farnese Hercules. Art was saved in the first century A. D."}]}
{"messages": [{"role": "assistant", "content": "D. by the devotion of portraiture, which gave a sense of reality and conviction which is entirely absent in the imaginative works. Lastly, a painstaking study and admiration of earlier works led, under the wealthy patronage of Hadrian (130 A. D.), to an eclectic revival which was wholly artificial, and passed away within a generation. We have fixed on sculpture as the most complete expression of Greek art; in other directions there is neither enough material nor enough research to give us a connected view. Not a single town, hardly a single house, in Greece has been excavated; there is no consecutive knowledge of the ordinary products and objects of life; and there is very little recorded of the discoveries of the tombs."}]}
{"messages": [{"role": "assistant", "content": "Not a single town, hardly a single house, in Greece has been excavated; there is no consecutive knowledge of the ordinary products and objects of life; and there is very little recorded of the discoveries of the tombs. The artistic interest of the sculpture and architecture has starved other branches of archæology, and for Greece more remains to be done than for some less celebrated lands. ITALY \nThe interest in Italy at the beginning of the nineteenth century was mainly for the sake of its second-hand version of Greek art, and for the architecture and painting of the Renaissance. On the contrary, now the objects from Greece itself have far eclipsed the Italian copies, and the interest lies in the early Italian civilization and its purely Roman derivatives; while modern taste values the mediæval art of Italy far from the bastard products of the florid age which followed. The first detailed studies in Italy were those on Pompeii, especially by Gell (1817), which made that debased style very popular, and paved the way for appreciation of better work. The various isolated discoveries of Etruscan tombs were summed up in the admirable work of Dennis (1848), which presented a general view of that civilization which has not been superseded."}]}
{"messages": [{"role": "assistant", "content": "The various isolated discoveries of Etruscan tombs were summed up in the admirable work of Dennis (1848), which presented a general view of that civilization which has not been superseded. The earlier Italic culture has been examined in many places where accidental discoveries have revealed it during the latter half of the nineteenth century, and especially in the systematic work of Zannoni, at Bologna (1870–75), and of Orsi, lately, in Sicily. The history of the city of Rome has been almost rewritten in the last thirty years owing to the great changes of the new government; these have been largely worked by Lanciani, and recorded by him and Middleton. The view of Italian history at present begins in the Stone age, which has been well studied, and has links with the later periods, as in the general use of black pottery. The earliest metal objects are very simple blades of daggers, found in graves, mingled with flint arrow-heads and knives. The admirable Italian plan of preserving whole burials undisturbed in museums enables us to see these graves complete in the Kircherian Museum."}]}
{"messages": [{"role": "assistant", "content": "The admirable Italian plan of preserving whole burials undisturbed in museums enables us to see these graves complete in the Kircherian Museum. A special branch of the early Bronze age life was the system of lake dwellings (natural or artificially water girt), which abound in the northern Italian lakes and over the plain of Lombardy. These towns (“terra mare”) are arranged on a rectangular plan, and form the earliest stage of many of the present cities. The full development of the Bronze age civilization seems to have been later than in Greece, at about 800 B. C., to which belong the great discoveries of tombs, weapons, and tools at Bologna, and the cemetery of Falerii. Upon all the native Italic civilization came an entirely different influence from the immigrant Etruscan."}]}
{"messages": [{"role": "assistant", "content": "Upon all the native Italic civilization came an entirely different influence from the immigrant Etruscan. Traditionally coming from Asia Minor, he brought art and religion which had no relation to the Italic. The earliest Etruscan paintings are strongly northern in style, influenced by north European feeling (Veii). But soon the Etruscan borrowed largely from other races, from the Greek mainly, but also from Assyria and Egypt. Thus the fascinating problem in Italy is to distinguish the various sources of Italic, Etruscan, Græco-Etruscan, Oriental-Etruscan, and pure Greek, which are found in all degrees of combination before Roman times, and which can still be traced through the Roman age. The characteristics of Etruscan taste are: (1) The extraneous objects and figures, such as rows of pendants to a metal vase, monstrous heads standing out from a bowl, and statuettes placed for handles; (2) in forms of vases and furniture, the combination of many different parts and curves which never form a whole design; (3) and in sculpture the large round head and staring eyes."}]}
{"messages": [{"role": "assistant", "content": "The characteristics of Etruscan taste are: (1) The extraneous objects and figures, such as rows of pendants to a metal vase, monstrous heads standing out from a bowl, and statuettes placed for handles; (2) in forms of vases and furniture, the combination of many different parts and curves which never form a whole design; (3) and in sculpture the large round head and staring eyes. In general, an air of clumsy adaptation by a race deficient in originality. The glory of the Etruscan was his engineering, which he handed as a legacy to Rome. Strange to say, although thousands of Etruscan inscriptions are known, and many words are translated, yet the language is sealed to us, and none of the many attempts to read it has succeeded. The scientific study of Etruscan tombs has been well followed lately, as shown in the Florence Museum, where a separate room is devoted to each city. In the south of Italy Greek art prevailed, and many of the finest works belong to this civilization."}]}
{"messages": [{"role": "assistant", "content": "In the south of Italy Greek art prevailed, and many of the finest works belong to this civilization. The Greek in Italy had rather different ideals to those of Greece; he started more from the level of Polykleitos and Praxiteles than from the severe age; his favorite type is that of youth and adolescence, never of maturity. The grace and feeling of such bronze statues as the Hermes and so-called Sappho of Herculaneum are peculiar to southern Italy. And when the Greek artist penetrated north and allied himself with the mechanical skill of the Etruscan, such splendid work was done as the Orator of Sanguineto. Rome in the earlier centuries was an Italic town which came under Etruscan influence as Tuscany was conquered. But from the age of foreign conquest in the first century B."}]}
{"messages": [{"role": "assistant", "content": "But from the age of foreign conquest in the first century B. C., Greek art in a debased form ruled over all else, and ran into utter degradation in the third century A. D. It was this art that the power of Rome spread around the whole Mediterranean, from Palmyra to Britain, and is the parent of most modern decoration. But in the great reconstruction of the empire under Diocletian the debased Greek taste was mostly shaken off, and Rome went back to the old Italic-Etruscan style and motives. The statues have the round heads and staring eyes of old Etruria; the taste for quaint accessories, such as lions supporting objects, came back and passed into mediæval art, and the exaggerated, lengthy forms of men and animals reappeared."}]}
{"messages": [{"role": "assistant", "content": "The statues have the round heads and staring eyes of old Etruria; the taste for quaint accessories, such as lions supporting objects, came back and passed into mediæval art, and the exaggerated, lengthy forms of men and animals reappeared. Of the Christian period De Rossi’s work in the catacombs has given a firm base of facts for the third to the sixth century A. D., the actual tomb and body of Saint Cecilia being the most striking result. The later Roman and mediæval age in Italy is full of interest, but in that—as in the rest of mediæval Europe—research has been mainly on architecture and objects which are not the result of excavation. INDIA \nThe Hindus have never been chronologists or historians, and their great Sanskrit literature tells practically nothing about the rise of Buddhism, the invasion of Alexander, or the spread of civilization in Indo-China. All before the Islamic conquest in the tenth century A."}]}
{"messages": [{"role": "assistant", "content": "All before the Islamic conquest in the tenth century A. D. is in a mist of Puranic mythology. Here, then, more than in other countries, archæology has restored the history, and done so entirely within the nineteenth century. The existence of Sanskrit literature was revealed to the West by Sir William Jones at the end of the last century, and this gave scope to Oriental scholars, while antiquities only interested the collector. But serious exploration was led by Prinsep, whose decipherment of the Asoka inscriptions in 1837, which ranks with the achievements of Champollion and Rawlinson, gave the key to a mass of inscriptions."}]}
{"messages": [{"role": "assistant", "content": "But serious exploration was led by Prinsep, whose decipherment of the Asoka inscriptions in 1837, which ranks with the achievements of Champollion and Rawlinson, gave the key to a mass of inscriptions. His assistant, Cunningham, excavated many sites and collected coins, being head of the Archæological Survey from 1861 to 1885. Fergusson was the historian of Indian architecture; Burgess has published the cave-temples in west and south India; Sewell in Madras and Führer in the northwest have excavated and explored, and a few native pundits have been educated to such research. The government, in financial difficulty, has withdrawn from the work, but the congress of Orientalists in 1897 resolved to establish an Indian exploration fund. Inscriptions abound in India, on copper plate, stone pillars, and native rock. Those in Sanskrit, or modern vernaculars, are records of land grants or local dynasties."}]}
{"messages": [{"role": "assistant", "content": "Those in Sanskrit, or modern vernaculars, are records of land grants or local dynasties. The oldest—in two different alphabets (of Semitic origin)—are the famous edicts of Asoka (third century B. C.), who has been called The Buddhist Constantine. He placed these monuments of his power and religion around his frontiers of northern India; but their meaning was forgotten until Prinsep’s decipherment. The Hindus seem to have a coinage of stamped silver plate before Alexander; but regular coinage begins in the Bactrian kingdoms (200 B. C.–200 A."}]}
{"messages": [{"role": "assistant", "content": "C.–200 A. D.), with Greek and native inscriptions. Since then the coinage is continuous, and invaluable for history. No stone building or sculpture is older than Alexander (327 B. C.), or certainly earlier than Asoka (264–233 B. C.)."}]}
{"messages": [{"role": "assistant", "content": "C.). Greek influence is plain in the Punjab, but native style is seen in the cave-temples. The richest results have been from the mounds, some of which are ruins of forts or palaces, but the more important are the _stupas_, lofty domes erected two to one thousand years ago to enshrine Buddhist relics. These domes are surrounded with sculptured reliefs of scenes in the life of Buddha, and are often dated by inscriptions. From one lately opened the Buddha relic has been sent to the King of Siam, the only Buddhist king. Much has been done by the government in publishing and providing casts and photographs; but India yet needs a scientific archæologist to record details with the accuracy demanded by modern research."}]}
{"messages": [{"role": "assistant", "content": "Much has been done by the government in publishing and providing casts and photographs; but India yet needs a scientific archæologist to record details with the accuracy demanded by modern research. AMERICA \nArchæological work in the United States and in Central America was begun by Squier about the middle of the century, and the attention thus drawn to the subject has borne fruit in the more accurate and scientific explorations connected with the surveying and geological departments, and, above all, those of the Smithsonian Bureau of Ethnology. The names of Whitney, Wright, Cyrus Thomas, Holmes, Fowke, Mindeleff, and others, will be familiar to all American readers by their work of the last twenty years, and need no introducing here. The earliest remains of man in America—or perhaps in the world—are those beneath the great lava beds of California; since those were deposited the rivers have cut their beds through two thousand to four thousand feet of lava rock, implying an erosion during tens, or perhaps hundreds, of thousands of years. But little can be assigned, however, with any certainty to a date before the Christian era, though mounds of refuse on both ocean shores may probably belong to an age before any human history. The most important studies have been those on the highest civilization of the continent, that of Central America."}]}
{"messages": [{"role": "assistant", "content": "The most important studies have been those on the highest civilization of the continent, that of Central America. The destroying Spaniards preserved but little of native record, except incidentally, and the first collector of Aztec manuscripts was Benaduci (1736), of whose treasures but an eighth survived his imprisonments and persecutions, one of the greatest disasters to history. The first great publication of manuscripts was the magnificent work of Lord Kingsborough (1830); and almost at the same time appeared Prescott’s history. Though the later researches have shown that the land was divided into many small kingdoms, rather than under one power, as Prescott supposed, yet his account of the calendar and chronology of the Aztecs has been verified and added to, and far more has been done in reading the manuscripts than he supposed possible. Aubin, after years of work in Mexico, brought to Europe manuscripts of an entirely new kind, showing a fully developed system of phonetic writing, which he has largely deciphered with success, having analyzed over one hundred syllabic values correctly. One of the most complete studies has been that of the Mayan Quiché peoples, and especially of the Mayans of Yucatan."}]}
{"messages": [{"role": "assistant", "content": "One of the most complete studies has been that of the Mayan Quiché peoples, and especially of the Mayans of Yucatan. In 1864 Landa’s work on Yucatan (written 1566) was rediscovered, and the account of the calendar has sufficed to enable Goodman to discover the meaning of a very large number of signs (1897); these enable the numerical documents to be translated, and show that a period of as much as eight thousand years was dealt with by the Mayans, perhaps belonging to mythical ages. The alphabetic signs of Landa have proved useless so far, and Goodman even disbelieves in any record except that of numbers. Seler has shown the identical origin of the signs used by Aztecs and Mayans for the days and months. Little had been done to make known these remains until the recent explorations, casts, and publications of Maudsley, who has worked magnificently for seventeen years at Copan, Palenque, and Chichen-Itza; these, however, are but three of innumerable cities of Guatemala and Yucatan that need exploration. In New Mexico the many ruins from the Colorado to the Rio Grande have been proved to resemble those of the modern Pueblo Indians, and to have none of the characteristics of Central American architecture; there are no sculptures, and the rock inscriptions are too primitive to be interpreted."}]}
{"messages": [{"role": "assistant", "content": "In New Mexico the many ruins from the Colorado to the Rio Grande have been proved to resemble those of the modern Pueblo Indians, and to have none of the characteristics of Central American architecture; there are no sculptures, and the rock inscriptions are too primitive to be interpreted. Nothing points to an Aztec occupation, and probably the ancestors of the present people were the builders. The innumerable earthworks of the Mississippi valley were formerly supposed to belong to some vanished race. And the view that they were connected with the Central American civilization is favored by the pyramid mound, which was hardly known otherwise, and by the excellence of the minor sculpture. But there are great differences between the two civilizations. The mound-builders were far inferior in metal-working, and their burial customs are peculiar."}]}
{"messages": [{"role": "assistant", "content": "The mound-builders were far inferior in metal-working, and their burial customs are peculiar. The use of materials from both east and west coasts shows an extensive commerce. The best summing up of the researches is that by Prof. Cyrus Thomas, after his extensive excavations. He concludes that the remains of the mound-builders show no great antiquity; that they were formed by tribes like the existing Indians; that the builders were of the same culture as were the Indians when discovered; that such mounds continued to be made and used for burial during the European period, and that the principal builders were the Cherokees. It will be seen now how totally our view of man’s history has been changed by the study of archæology, and how fundamentally this science affects our ideas of the past and our expectations for the future of our race."}]}
{"messages": [{"role": "assistant", "content": "It will be seen now how totally our view of man’s history has been changed by the study of archæology, and how fundamentally this science affects our ideas of the past and our expectations for the future of our race. The main outlines have been dimly seen; but in every country the greater part yet remains to be done, and in Turkey, Persia, and China most important civilizations are as yet quite untouched by exploration. The new century will no doubt see a harvest from these lands; and it is to be hoped that what yet remains in the safe keeping of the earth may be found by able men, who will preserve it for instruction and enable posterity to trace the fortunes of our species. [India and America are here treated with the assistance of Mr. J. S."}]}
{"messages": [{"role": "assistant", "content": "S. Cotton and Mr. D. MacIver.] \n            W. M. FLINDERS PETRIE."}]}
{"messages": [{"role": "assistant", "content": "FLINDERS PETRIE. ASTRONOMY \n\nIn looking back over a century’s work in the oldest of the sciences, one is struck not only by the enormous advance that has been made in those branches of the science dealing with the motions of the heavenly bodies which were cultivated at least eight thousand years ago by early dwellers in the valleys of the Nile, Tigris, and Euphrates, but with the fact that during the century that has just passed away a perfectly new science of astronomy arose. By annexing physics and chemistry astronomers now study the motions of the particles of which all celestial bodies are composed; a new molecular astronomy has now been firmly established side by side with the old molar astronomy which formerly alone occupied the thoughts of star-gazers. Along this new line our knowledge has advanced by leaps and bounds, and the results already obtained in expanding and perfecting man’s views of nature in all her beauty and immensity are second to none which have been garnered during the last hundred years. THE POSITION AT THE BEGINNING OF THE CENTURY \nIt may be well before attempting to obtain a glimpse of recent progress that we should try to grasp the state of the science at the time when the nineteenth century was about to dawn, and this, perhaps, can be best accomplished by seeing what men were working at this period, at which the greatest activity was to be found in Germany; there was no permanent observatory in the southern hemisphere or in the United States. First and foremost among the workers—he has, in fact, been described as “the greatest of modern astronomers”—was William Herschel, a German domiciled in England."}]}
{"messages": [{"role": "assistant", "content": "First and foremost among the workers—he has, in fact, been described as “the greatest of modern astronomers”—was William Herschel, a German domiciled in England. In the year 1773 he hired a telescope, and with this small instrument he obtained his first glimpses of the rich fields of exploration open in the skies. From that time onward he had one fixed purpose in his mind, which was to obtain as intimate knowledge as possible of the construction of the heavens. To do this, of course, great optical power was necessary, and such was his energy that, as large instruments were not to be obtained at any price, he set to work and made them himself. Herschel presented the beginning of the nineteenth century not only with a definite idea of the constitution of the stellar system, based on a connected body of facts and deductions from facts, as gleaned through his telescopes, but observations without number in many fields. He discovered a new planet, Uranus, and several satellites of the planets; published catalogues of nebulæ; established the gravitational bond between many “double stars,” and carried on observations of the sun, then supposed to be a habitable globe."}]}
{"messages": [{"role": "assistant", "content": "He discovered a new planet, Uranus, and several satellites of the planets; published catalogues of nebulæ; established the gravitational bond between many “double stars,” and carried on observations of the sun, then supposed to be a habitable globe. What Herschel did for observational astronomy and deductions therefrom, Laplace did for the furtherance of our knowledge concerning the exact motions of the bodies comprising the solar system. Newton had long before announced that gravitation was universal, and Laplace brought together investigations undertaken to determine the validity of this law. These were given to the world in his wonderful book on _Celestial Mechanics_, the first volumes of which appeared in 1799. A survey of the work of these two great astronomers gives one an idea of what was going on in observational and mathematical astronomy at the beginning of the century. The study was now destined to make rapid strides, as not only were new optical instruments—some designed for special purposes—introduced, new mathematical processes applied, fresh fields for research opened up, but the number of workers was considerably augmented by the increased means available; so much so, indeed, that the first astronomical periodical was founded by Von Zach in 1800 to facilitate intercommunications between the observers."}]}
{"messages": [{"role": "assistant", "content": "The study was now destined to make rapid strides, as not only were new optical instruments—some designed for special purposes—introduced, new mathematical processes applied, fresh fields for research opened up, but the number of workers was considerably augmented by the increased means available; so much so, indeed, that the first astronomical periodical was founded by Von Zach in 1800 to facilitate intercommunications between the observers. The first evening of the nineteenth century (January 1, 1801) augured well for progress. It had long been thought that all the members of the solar system had not as yet been discovered, and there was a very notable gap between the planets Mars and Jupiter, indicated by Bode’s law. Observers were organized to make a thorough search for the missing planet, portions of the sky being divided between them for minute examination. It fell to the Italian observer, Piazzi, to discover a small body which was moving in an orbit between these two planets on the date named. The century thus began with a sensation, and because the new body, which was named “Ceres,” was not of sufficient size to be accepted as the “missing planet,” the idea was suggested that perhaps it was a fragment of a larger planet that had been blown to pieces in the past."}]}
{"messages": [{"role": "assistant", "content": "The century thus began with a sensation, and because the new body, which was named “Ceres,” was not of sufficient size to be accepted as the “missing planet,” the idea was suggested that perhaps it was a fragment of a larger planet that had been blown to pieces in the past. An opportunity here arose for mathematical astronomy to come to the help of the observer, for Ceres soon was lost in the solar rays, and in order to rediscover it, after it had passed conjunction, an approximate knowledge of its path and future position was necessary. With the then existing methods of computation of orbits it was imperative to have numerous measured positions to use as data for the calculation. The scanty data available in the case of Ceres were not sufficient for the application of the method. The occasion discovered a man, one of the greatest mathematicians of the nineteenth century, Karl Frederick Gauss, who, although only twenty-five years of age, undertook the solution of the problem by employing a system which he had devised, known as “the method of least squares,” which enabled him to obtain a most probable result from a given set of observations. This, with a more general method of orbit computation, also elaborated by himself, was sufficient to enable him to calculate future positions of Ceres, and on the anniversary of the original discovery, Olbers, another great pioneer in orbit calculations, found the planet in very nearly the position assigned by Gauss."}]}
{"messages": [{"role": "assistant", "content": "This, with a more general method of orbit computation, also elaborated by himself, was sufficient to enable him to calculate future positions of Ceres, and on the anniversary of the original discovery, Olbers, another great pioneer in orbit calculations, found the planet in very nearly the position assigned by Gauss. So great was the curiosity regarding the other portions of the planet, which was supposed to have been shattered, that numerous observers at once commenced to search after other fragments. These were the _actualities_ of 1801 and thereabouts; but the seed of much future work was sown. Kant and Laplace had already occupied themselves with theories as to the world formation, and spectrum analysis as applied to the heavenly bodies may be said to have been started by Wollaston’s observations of dark lines in the solar spectrum in 1802. Fraunhofer was then a boy at school. In the same year the first photographic prints were produced by Wedgewood and Davy."}]}
{"messages": [{"role": "assistant", "content": "In the same year the first photographic prints were produced by Wedgewood and Davy. OBSERVATORIES \nIt has been stated that at the beginning of the century there were no permanent observatories either in the southern hemisphere or in the United States. The end of the century finds us with two hundred observatories all told, of which fourteen are south of the equator and forty-seven in the United States, among which latter are the best-equipped and most active in the world. The observatory of Parramatta was the first established (1821) in the southern hemisphere. This was followed by that at the Cape of Good Hope in 1829. Of the more modern southern observatories from which the best work has come we may mention Cordova, the seat of Gould’s important investigations, established in 1868, and Arequipa, a dependency of Harvard, whence the spectra of the southern stars have been secured, erected still more recently (1881)."}]}
{"messages": [{"role": "assistant", "content": "Of the more modern southern observatories from which the best work has come we may mention Cordova, the seat of Gould’s important investigations, established in 1868, and Arequipa, a dependency of Harvard, whence the spectra of the southern stars have been secured, erected still more recently (1881). I believe, but I do not know, that the large number of American observatories have radiated from Cincinnati, where, in consequence of eloquent appeals, both by voice and pen, from Mitchell, then professor of astronomy, an observatory was commenced in 1845. There can be no doubt that at the present moment, with the numerous well-equipped and active observatories, and the careful and thorough teaching established side by side with them, which enables numberless students to use the various instruments, the United States, in matters astronomical, fills the position occupied by Germany at the beginning of the century. In Europe special observatories have been established at Meudon, Kensington, and Potsdam, so that new astrophysical inquiries may be undertaken without interfering with the prosecution or extension of the important meridional work carried on at Paris, Greenwich, and Berlin. A large proportion of the observations made by the Lick and Yerkes observatories in the United States has been astrophysical. One of the special inquiries committed to the charge of the Solar Physics Observatory at Kensington at its establishment by the British government had relation to the possibility of running home meteorological changes on the earth, especially those followed by drought and famines in various parts of the empire, to the varying changes in the sun indicated by the ebb and flow of spots on its surface."}]}
{"messages": [{"role": "assistant", "content": "One of the special inquiries committed to the charge of the Solar Physics Observatory at Kensington at its establishment by the British government had relation to the possibility of running home meteorological changes on the earth, especially those followed by drought and famines in various parts of the empire, to the varying changes in the sun indicated by the ebb and flow of spots on its surface. With this end in view observations of the sun were commenced in India and the Mauritius to supplement those taken at Greenwich. At the same time other daily observations of sun spots by a different method were commenced at Kensington. This kind of work was at first considered ideally useless; we shall see later on what has become of it. IMPROVEMENTS IN TELESCOPES \nThe progress in astronomical science throughout the nineteenth century has naturally to a great extent depended upon the advances made both in the optics of the telescope and the way in which they are mounted, either with circles to record exact times and positions, or made to move so as to keep a star or other celestial objects in the field of view while under observation. The perfection of definition and the magnitude of the lenses employed in the modern instrument have been responsible for many important discoveries."}]}
{"messages": [{"role": "assistant", "content": "The perfection of definition and the magnitude of the lenses employed in the modern instrument have been responsible for many important discoveries. Ever since the telescope was invented—Galileo’s lens was smaller than those used in spectacles—men’s minds have been concentrated on producing instruments of larger and larger size to fathom the cosmos to its innermost depths. At the beginning of the century we were, as we have seen already, in possession of reflectors of large dimensions; Herschel’s four-foot mirror, the instrument he was using in 1801, which had a focal length of forty feet, was capable of being employed with high magnifying powers; and it was the judicious use of these, on occasions when the finest of weather prevailed, that enabled him to enrich so extensively our knowledge of the stellar and planetary systems. For the ordinary work of astronomy, however, especially when circles are used, refractors are the more suitable instruments. This form suffers less from the vicissitudes of weather and temperature, and is, therefore, more suited where exact measurements are required. Towards the end of the eighteenth century a Swiss artisan, Pierre Guinard, after many years of patient labor, succeeded in producing pure disks of flint glass as large as six inches in diameter."}]}
{"messages": [{"role": "assistant", "content": "Towards the end of the eighteenth century a Swiss artisan, Pierre Guinard, after many years of patient labor, succeeded in producing pure disks of flint glass as large as six inches in diameter. The modern refracting telescope thus became possible. In 1804 there was started at Munich the famous optical and mechanical institute, which soon made its presence felt in the astronomical world. Reforms in instrument making were soon taken in hand, and under the leadership of the great German astronomer, Bessel, great strides were made in instruments of precision. Fraunhofer, who had been silently working away at the theory of lenses, and making various experiments in the manufacture of glass, was joined, in 1805, by Guinard. In 1809 Troughton invented a new method of graduating circles, according to Airy the greatest improvement ever achieved in the art of instrument making."}]}
{"messages": [{"role": "assistant", "content": "In 1809 Troughton invented a new method of graduating circles, according to Airy the greatest improvement ever achieved in the art of instrument making. In 1824 Fraunhofer successfully completed and perfected an object-glass of 9.9 inches in diameter for the Dorpat Observatory. This objective might literally have been called a “giant,” for nothing approaching it in size had been previously made. England, which was at one time the exclusive seat of the manufacture of refracting telescopes, was now completely outstripped by both Germany and France, and for this we had to thank “the short-sighted policy of the government, which had placed an exorbitant duty on the manufacture of flint glass.” In 1833 the Dorpat refractor was eclipsed by one of fifteen inches aperture made for the Pulkowa Observatory by Merz & Mähler, Fraunhofer’s successors, who about ten years later supplied a similar instrument to Harvard College. At that time Lord Rosse emulated with success the efforts of Herschel and rehabilitated the reflector by producing a metallic mirror of six-foot aperture and fifty-four-foot focal length which he mounted at Parsonstown. The speculum weighed no less than four tons."}]}
{"messages": [{"role": "assistant", "content": "The speculum weighed no less than four tons. To mount this immense mass efficiently and safely was a work of no light nature, but he successfully accomplished it, and eventually both mirror and the telescope, which weighed now altogether fourteen tons, were so well counterpoised that they could be easily moved in a limited direction by means of a windlass worked by two men. The perfection of the “seeing” qualities of this instrument and its enormous light-grasping powers were particularly striking, and observational astronomy was considerably enriched by the discoveries made with it. Speculum metal was not destined to stay; ten years later (1857) the genius of Léon Foucault introduced glass mirrors with a thin coating of silver deposited chemically, and these have now universally superseded the metallic ones. The long supremacy of Germany in the matter of refractors was broken down ultimately by the famous English optician and engineer, Thomas Cooke, of York. His first considerable instrument, one of seven inches aperture, was finished in 1851; and in 1865, a year before his lamented death, he completed the first of our present giant refractors, one of twenty-five inches aperture, for Mr."}]}
{"messages": [{"role": "assistant", "content": "His first considerable instrument, one of seven inches aperture, was finished in 1851; and in 1865, a year before his lamented death, he completed the first of our present giant refractors, one of twenty-five inches aperture, for Mr. Newall, of Gateshead. In consequence of the success of Cooke’s achievement other large refractors were soon undertaken. Alvan Clarke, the famous optician of Cambridgeport, Massachusetts, at once commenced a twenty-six-inch for the Washington Observatory. The next was one of twenty-seven inches, made by Grubb for the Vienna Observatory. Object-glasses now grew inch by inch in size, depending on the increased dimensions of disks that could be satisfactorily cast."}]}
{"messages": [{"role": "assistant", "content": "Object-glasses now grew inch by inch in size, depending on the increased dimensions of disks that could be satisfactorily cast. Gautier, of Paris, completed a twenty-nine-and-a-half-inch for the Nice Observatory, while Alvan Clarke made an objective of thirty inches for Pulkowa. In 1877 the latter successfully completed the mounting of an objective of thirty-six inches for the Lick Observatory, but this immense lens was only achieved after a great number of failures. Even this large object-glass was surpassed in size by the completion in 1892 of the forty-inch which he made for the Yerkes Observatory, and by that made by Gautier for the Paris Exhibition of 1900. So much, then, for the largest refractors. In recent years, since the introduction of the silver on glass mirrors, with their stability of figure and brilliant surface, which can be easily renewed, reflectors of large apertures are again being produced."}]}
{"messages": [{"role": "assistant", "content": "In recent years, since the introduction of the silver on glass mirrors, with their stability of figure and brilliant surface, which can be easily renewed, reflectors of large apertures are again being produced. The first of these was one of thirty-six inches aperture made by Calver for Dr. Common, who demonstrated its fine qualities and his own skill by the beautiful photographs of the nebula of Orion he was enabled to secure with it. Dr. Common himself has since turned his attention to the making and silvering of large mirrors of this kind, and the largest he has actually completed and mounted equatorially is one with a diameter of five feet. Another of thirty-six inches aperture is in use at the Solar Physics Observatory at Kensington."}]}
{"messages": [{"role": "assistant", "content": "Another of thirty-six inches aperture is in use at the Solar Physics Observatory at Kensington. The progress of depositing silver on glass has led of late years to important developments in which _plane_ mirrors are used. Foucault was the first to utilize such mirrors in his “siderostat,” in which such a mirror is made to move in front of a horizontal fixed telescope, which may be of any focal length, and no expensive dome or rising floor is required. The plane mirror of the siderostat in the Paris Exhibition telescope is six feet in diameter. A variation of this instrument is the cœlostat more recently advocated by Lippmann. The Coudé equatorial mounting also depends upon the use of plane mirrors; with such a telescope the observer is at rest at a fixed eye-piece or camera in a room which may be kept at any temperature."}]}
{"messages": [{"role": "assistant", "content": "The Coudé equatorial mounting also depends upon the use of plane mirrors; with such a telescope the observer is at rest at a fixed eye-piece or camera in a room which may be kept at any temperature. Now that in astronomical work eye observations are indispensably supplemented by the employment of photography, an important modification of the refracting telescope has become necessary; this was first suggested by Rutherfurd. The ordinary achromatic object-glass consists, as a rule, of two lenses, one made of flint and the other of crown glass; but in this form the photographic rays are not brought to the same focus as the visual rays. This, however, can be achieved by employing three lenses instead of two, each of different kinds of glass. The most modern improvement in the telescope is due to Mr. Dennis Taylor, of Cooke & Sons, and to Dr."}]}
{"messages": [{"role": "assistant", "content": "Dennis Taylor, of Cooke & Sons, and to Dr. Schott and Professor Abbe, whose researches in the manufacture of old and new varieties of optical glass have rendered Mr. Taylor’s results feasible. By the Taylor lens outstanding color is abolished, all the rays being brought absolutely to the same focus; such lenses can therefore be used either for visual observations or for photography for spectroscopy. SPECTROSCOPIC ASTRONOMY \nThe branch of physics which at the present day has assumed such mighty and far-reaching proportions in astronomical work is that dealing with spectrum analysis, which, although suggested as early as the time of Kepler, did not receive any impetus as regards its application to celestial bodies until the beginning of the present century at the hands of Wollaston and Fraunhofer. Then, however, it still lacked the chemical touch supplied afterwards by Kirchhoff and Bunsen."}]}
{"messages": [{"role": "assistant", "content": "Then, however, it still lacked the chemical touch supplied afterwards by Kirchhoff and Bunsen. They showed us that the spectrum observed when the light from any heated body is passed through a prism is an index to the chemical composition of the light source; the constitution of a vapor when in a condition to absorb light can be determined by an extension of the same principle, first demonstrated by Stokes, Angström, and Balfour Stewart, when the century was about half completed. The first celestial body towards which the spectroscope was turned was our central luminary, the sun. Wollaston first discovered that its spectrum was crossed by a few dark lines; we learned next from Fraunhofer, who in 1814 worked with instruments of greater power, that the solar spectrum was crossed not only by a few dark lines, but by some hundreds. Not content with examining the light of the sun, Fraunhofer turned his instrument towards the stars, the light of which he also examined, so that he may be justly called the inventor of stellar spectrum analysis. It is not to the credit of modern science that from this time forward spectrum analysis did not become a recognized branch of scientific inquiry, but, as a matter of fact, Fraunhofer’s observations were buried in oblivion for nearly half a century."}]}
{"messages": [{"role": "assistant", "content": "It is not to the credit of modern science that from this time forward spectrum analysis did not become a recognized branch of scientific inquiry, but, as a matter of fact, Fraunhofer’s observations were buried in oblivion for nearly half a century. The importance of them was not recognized till the origin of the dark lines, both in sun and stars, had been explained by Stokes and others, as before stated. The lines in the solar spectrum were mapped with great diligence by Kirchhoff in 1861 and 1862, and later by Angström and Thalen, and this was done side by side with chemical work in the laboratory. The chemistry of the sun was thus to a great extent revealed; it was no longer a habitable globe, but one with its visible boundary at a fierce heat, surrounded by an atmosphere of metallic vapors, chief among them iron, also in a state of incandescence. To these metallic vapors Angström added hydrogen shortly afterwards. Here, then, was established a firm link between the heavens and the earth; the first step to the problem of the chemistry of space had been taken."}]}
{"messages": [{"role": "assistant", "content": "Here, then, was established a firm link between the heavens and the earth; the first step to the problem of the chemistry of space had been taken. It was only natural that as advances were made the instrumental equipment should keep pace with them. Spectroscopes were built on a larger scale; more prisms, which meant greater dispersion, were employed to render the measurements of the lines in spectra more accurate. The growth of our knowledge especially necessitated the making of maps of the lines in the solar spectrum, and in the spectra of the chemical elements which had been compared with it on a natural scale. This was done by Angström, who utilized for this purpose the diffraction grating invented by Fraunhofer, and defined the position of all lines in spectra by their “wave lengths,” in ten-millionths of a millimetre or “tenth-metres.” \nIn 1862 Rutherfurd extended Fraunhofer’s work on the stars by a first attempt at classification. Two years later Huggins and Miller produced maps of the spectra of some stars."}]}
{"messages": [{"role": "assistant", "content": "Two years later Huggins and Miller produced maps of the spectra of some stars. Donati demonstrated that comets gave radiation spectra, and Huggins did the same for nebulæ. By these observations comets and nebulæ were shown to be spectroscopically different from stars, which at that time were studied by their dark lines only. Chiefly by the labors of Pickering, the energetic head of the Harvard Observatory, science has been enriched during the later years by observations of thousands of stellar spectra, the study of which has brought about the most marvellous advance in our knowledge. These priceless data have enabled us now to classify the stars not only by their brightness, or their color, but by their chemistry. Next to be chronicled is the application of the so-called Doppler-Fizeau principle, which teaches us that when a light source is approaching or receding from us the light waves are crushed together or drawn out, so that the wave length is changed."}]}
{"messages": [{"role": "assistant", "content": "Next to be chronicled is the application of the so-called Doppler-Fizeau principle, which teaches us that when a light source is approaching or receding from us the light waves are crushed together or drawn out, so that the wave length is changed. The amount of change gives us the velocity of approach or recess, so that the rate of movement of stars towards or from the earth, or the up-rush or down-rush of the solar vapors on the sun’s disk can be accurately determined. A further utilization of this principle is found when the stars are so close together that they appear as one if the plane of motion passes near the earth. A line common to the spectra of both stars will appear double twice in each revolution, when the motion to or from the earth, or, as it is termed, “in the line of sight,” is greatest. “Spectroscopic doubles,” as these stars are called, yield up many of their secrets which otherwise would elude us. Their time of revolution, the size of the orbit, and the combined mass can be determined."}]}
{"messages": [{"role": "assistant", "content": "Their time of revolution, the size of the orbit, and the combined mass can be determined. To return from the stars to the sun. By the device of throwing an image of the sun on the slit of the spectroscope the spectra of solar spots have been studied from 1866 onward, and a little later the brighter portions of the sun’s outer envelopes, revealed till then only during eclipses, were brought within our ken spectroscopically, so that they are now studied every day. CELESTIAL PHOTOGRAPHY \nWedgewood and Davy, in 1802, made prints on paper by means of silver salts, but it was not until 1830 that Niepce and Daguerre founded photography, which Arago, in an address to the French Chamber, at once suggested might subsequently be used to record the positions of stars. In 1839 we find Sir John Herschel carrying out a series of experiments so important for our correct knowledge of the sequence of steps in the early stages of photography that I have no hesitation in quoting from one of Herschel’s manuscripts relating to a deposit on a glass plate of “muriate” [chloride] of silver from a mixed solution of the nitrate with common salt. The manuscript states: “After forty-eight hours [the chloride] had formed a film firm enough to bear draining the water off very slowly by a siphon."}]}
{"messages": [{"role": "assistant", "content": "The manuscript states: “After forty-eight hours [the chloride] had formed a film firm enough to bear draining the water off very slowly by a siphon. Having dried it, I found that it was very little affected by light, and by washing it with nitrate of silver, weak, and drying it, it became highly sensitive. In this state I took a camera picture of the telescope on it.” \nThe original of the above-mentioned photograph, the first photograph ever taken on glass, is now in the science collection at the Victoria and Albert Museum, South Kensington. In the early days of photography colored glasses were first used to investigate the action of different colors on the photographic plate. Sir John Herschel was among the first to propose that such investigations should be made direct with a spectrum, and he, like Dr. J."}]}
{"messages": [{"role": "assistant", "content": "J. W. Draper, stated that he had found a new kind of light beyond the blue end of the spectrum, as the photographic plate showed a portion of the spectrum there which was not visible to the eye. Advance followed advance, and in 1842 Becquerel photographed the whole solar spectrum, in colors, with nearly all the lines registered by the hand and eye of Fraunhofer, not only the blue end, but the complete spectrum, from Draper’s “latent light,” as he called the ultra-violet rays, to the extreme red end. The first photograph of a celestial object was one of the moon, secured by Dr. J."}]}
{"messages": [{"role": "assistant", "content": "J. W. Draper in 1840; we had to wait till 1845, so far as I know, before a daguerreotype was taken of the sun; this was done by Foucault and Fizeau, while the first photograph of a star—Vega—was taken at Harvard in 1850. After the introduction of the wet-collodion process regular photography of the sun’s surface was commenced, at Sir John Herschel’s recommendation, at Kew in 1858, and the total solar eclipse of 1860 was made memorable by the photographs of De La Rue, who before that time had secured most admirable photographs of the moon, as also had Rutherfurd. Photography now began to pay the debt she owed to spectrum analysis. The first laboratory photograph of the spectra of the chemical elements was taken by Dr."}]}
{"messages": [{"role": "assistant", "content": "The first laboratory photograph of the spectra of the chemical elements was taken by Dr. W. A. Miller in 1862. Rutherfurd was the first to secure a photograph of the solar spectrum with considerable dispersion by means of prisms. In 1863 Mascart undertook a complete photographic investigation of the ultra-violet portion of the solar spectrum, a work of no mean magnitude."}]}
{"messages": [{"role": "assistant", "content": "In 1863 Mascart undertook a complete photographic investigation of the ultra-violet portion of the solar spectrum, a work of no mean magnitude. He, however, did not employ a train of prisms for producing the spectrum, but a diffraction grating, using the light reflected from the first surface. The first photograph of the spectrum of a star was secured by Henry Draper, the son of Dr. J. W. Draper, one of the pioneers in photography in 1872."}]}
{"messages": [{"role": "assistant", "content": "Draper, one of the pioneers in photography in 1872. It was not till the introduction of dry plates in 1876 that the photography of the fainter celestial objects or of their spectra was possible, as a long exposure was naturally required. Stellar spectra were photographed by Huggins in 1879, and in the next year Draper photographed the nebula of Orion. As the dry plates became more rapid, and as longer exposures were employed, revelation followed revelation; the nebulæ as seen by the naked eye, and even some stars, were found by the Henrys, Roberts, Max Wolf, Barnard, and others, to be but the brighter kernels of large nebulous patches. This new application of photography, depending upon long exposures (the longest one I know of has extended to forty hours), had an important reflex action on the mechanical parts of the telescope; it was not only necessary to keep the faintest star exactly on the same part of the plate during the whole of the exposure, but night after night the stellar image must be brought on to the same part of the plate so that the exposure might be continued. A system of electric control of the going of the driving-clock of the telescope by means of a sidereal clock was introduced, the simplest one being designed by Russell, of Sydney; a most elaborate one by Grubb, of Dublin."}]}
{"messages": [{"role": "assistant", "content": "A system of electric control of the going of the driving-clock of the telescope by means of a sidereal clock was introduced, the simplest one being designed by Russell, of Sydney; a most elaborate one by Grubb, of Dublin. Another application of the method of long exposures has been the discovery of minor planets by the trails impressed by their motion among the stars on the photographic plates on which the images of both are impressed. A complete spectroscopic survey of the stars by means of photography was commenced in 1886 at Harvard College, as a memorial to Draper, who died while he was laboring diligently and successfully in securing advances in astrophysical inquiries. To carry on this work at Harvard, Professor Pickering wisely reverted to the method first employed by Fraunhofer, and utilized by Respighi and another in 1871, of placing prisms in front of the object-glass. In the photographing of stellar spectra by means of objective prisms, the driving-clock of the telescope must _not_ go exactly at sidereal rate, but at certain speeds depending on the brightness and position of the star under examination. This is necessary because the image of the spectrum of a star on the photograph is only a thin line in which it is impossible to see the spectral lines; the spectrum must be broadened, and this is accomplished by making the star image “trail” to a certain degree on the plate."}]}
{"messages": [{"role": "assistant", "content": "This is necessary because the image of the spectrum of a star on the photograph is only a thin line in which it is impossible to see the spectral lines; the spectrum must be broadened, and this is accomplished by making the star image “trail” to a certain degree on the plate. This trailing is accomplished by means of the clock, the rate of which is made to vary. In this way the trail of a spectrum of a star on the photographic plate is always obtained of the same width, while the density of the image is made fairly constant by increasing the rate for bright stars and decreasing it for fainter ones. In this way spectra of the brighter stars rivalling in perfection and detail those obtained of the spectrum of the sun itself thirty years ago have been obtained. Such photographs have rendered a minute chemical classification of the stars possible. One of the most interesting applications of photography to spectrum analysis during the latter part of the century has been the utilization by Messrs."}]}
{"messages": [{"role": "assistant", "content": "One of the most interesting applications of photography to spectrum analysis during the latter part of the century has been the utilization by Messrs. Deslandres and Hale of a suggestion made by Janssen, that by employing photography images of the sun and its surroundings can be obtained in light on one wave length. In this way we can study the distribution of any one of the chemical constituents of the sun separately, and note its behavior, not only on the sun itself, but in the atmosphere which enfolds the disk. It is strange that, in spite of the suggestions of Faye, and others after him, one of the great advantages of the employment of photography in astronomical work, namely, the abolition of “personal equation,” has so far been almost entirely neglected. What “personal equation” is can be perhaps illustrated by considering an observer who is observing the transit of a star over the wires in a transit instrument. His object is to note the exact time, to a fraction of a second, when a star passes each wire; and this is done by listening to the beats of a clock near at hand and estimating the fractions."}]}
{"messages": [{"role": "assistant", "content": "His object is to note the exact time, to a fraction of a second, when a star passes each wire; and this is done by listening to the beats of a clock near at hand and estimating the fractions. Some observers constantly note the time either a little in advance or a little later than the actual time, and this small distance between the observer and the true times is more or less constant for each observer. This difference has to be taken into account for every observation. Even the use of the chronograph in transit work, by which the observation is electrically recorded, does not entirely eliminate the error. The photographic method of transit work has been experimented on, but, so far as I know, it has not yet been used at more than one or two observatories. It will doubtless eventually rid us of “personal equation” entirely, for the star image may be photographed and the time recorded by the same current of electricity."}]}
{"messages": [{"role": "assistant", "content": "It will doubtless eventually rid us of “personal equation” entirely, for the star image may be photographed and the time recorded by the same current of electricity. At the end of the century we could almost say that except in relation to the work of the meridional observatories, photographic methods of recording observations had become exclusively used. One of the cases in which its utility is most in evidence is in the matter of eclipse observations. Spectra of the sun’s surroundings containing a thousand lines are taken in a second of time, thus replacing five or six doubtful eye observations by wealth of results which have enabled the recent vast progress to be secured. CATALOGUES \nCatalogues of the stars were among the first scientific records started by man, and so long as only the naked eye was used the work was not difficult, as only approximate positions were attempted, even by Hipparchus; but long before the eighteenth century dawned the problem was entirely changed by the invention of the telescope and by the provision of accurately divided circles; not only could better positions be recorded, but the number of stars to be catalogued was enormously increased, and, furthermore, other objects, nebulæ, presented themselves in considerable numbers. In 1801 the star catalogues chiefly relied on were those of Lacaille, containing about three thousand stars scattered over the whole heavens."}]}
{"messages": [{"role": "assistant", "content": "In 1801 the star catalogues chiefly relied on were those of Lacaille, containing about three thousand stars scattered over the whole heavens. Maskelyne, who was then Astronomer Royal, had published in 1790 a catalogue of thirty-six fundamental stars, chiefly for the purposes of navigation. The first great catalogue of the century was the _Fundamenta Astronomiae_ of Bessel, produced in 1818. This contained three thousand two hundred and twenty-two stars. The Bonn _Durchmüsterung_, with its catalogue of three hundred and twenty-four thousand one hundred and ninety-eight stars in the northern hemisphere, and the corresponding atlas published in 1857–63, was the next memorable achievement in this direction. For it we have to thank Bessel and Argelander and a perfect system of work."}]}
{"messages": [{"role": "assistant", "content": "For it we have to thank Bessel and Argelander and a perfect system of work. Another monumental catalogue dealing with the stars in the southern heavens has been that of the southern stars observed by Gould (1866). While the century was closing, another catalogue, far more stupendous than anything which could be conceived possible a few years ago, was steadily being compiled. This we owe to the far-sightedness and energy of Admiral Mouchez, a late director of the Paris Observatory. The work was commenced in 1892. The whole heavens, north and south alike, have been divided into zones, and the chief observatories on the earth’s surface are busy night after night in taking photographs of that part intrusted to them."}]}
{"messages": [{"role": "assistant", "content": "The whole heavens, north and south alike, have been divided into zones, and the chief observatories on the earth’s surface are busy night after night in taking photographs of that part intrusted to them. The whole heavens are thus being made to write their autobiography, and the total gain to the astronomy of the future of this most priceless record can perhaps be scarcely grasped as yet, although the advantage of being able at any point of future time to see on a photographic plate what the heavens are telling now is sufficiently obvious. Catalogues of the stars have, of course, led to other minor catalogues of various classes of stars, binary, variable, and the like. In the later years catalogues of stars according to their spectra have enriched science. The first extensive catalogue of stellar spectra was published by Vogel. It dealt with four thousand and fifty-one stars, and appeared in 1883; it has since been followed by the Draper catalogue, based upon photographs of the spectra, which contains a much larger number."}]}
{"messages": [{"role": "assistant", "content": "It dealt with four thousand and fifty-one stars, and appeared in 1883; it has since been followed by the Draper catalogue, based upon photographs of the spectra, which contains a much larger number. With regard to nebulæ, Herschel published his third catalogue in 1802. The last catalogue of this nature is by Dreyer (1888), and contains seven thousand eight hundred and forty of these objects. In the time of Tycho they could be counted on the fingers of one hand. INVESTIGATIONS OF SOME IMPORTANT ASTRONOMICAL CONSTANTS \nThe nineteenth century was fruitful in the determination of many numerical values which are all important in enabling us to determine the distance and masses of the heavenly bodies, thereby giving us a firm grasp not only of the dimensions of our own system, but of those scattered in the celestial spaces. To take the distances first."}]}
{"messages": [{"role": "assistant", "content": "To take the distances first. We must begin with the exact measure of the earth; for this we must measure the exact length of an arc of meridian or of parallel—that is, a stretch of the earth’s surface lying north and south or east and west, between places of which the latitudes are accurately known in the former case, and the longitude in the latter. In either case we can determine the number of miles which go to a degree. Beginning at the opening of the nineteenth century with an arc of meridian of two degrees measured by Gauss, from Göttingen to Altona, the arcs of meridian grew longer as the century grew older, till, at the close, the measurement of an arc of meridian from the Cape to Cairo, embracing something like sixty-eight degrees of latitude, was mooted. The measurements of arcs of parallel have been developed by the rapid extension of telegraphic communications, which now permit the longitude of the terminal stations to be determined with the greatest accuracy. Thanks to this work, we now have the size of our planet to a few miles."}]}
{"messages": [{"role": "assistant", "content": "Thanks to this work, we now have the size of our planet to a few miles. The polar diameter is 41,709,790 feet, but the equator is not a circle: the equatorial diameter from longitude 8 degrees 15 minutes west to longitude 188 degrees 15 minutes west is 41,853,258 feet; that at right angles to it is 41,850,210 feet—that is, some thousand yards shorter. The earth, then, is shaped like an orange slightly squeezed. Knowing the earth’s diameter, we can obtain the sun’s distance by several methods, the old one by observing transits of Venus, one of which Cook went out to observe in 1768, and two of which recurred in 1874 and 1882; new ones by observations of Mars or one of the minor planets at a favorable opposition, and by determining the velocity of light. The recent discovery of a minor planet, Eros, which in one part of its orbit is nearer the earth than Mars, has recently revived interest in this method, and a combined attack is in contemplation. It has been long known that light has a finite velocity, but we had to wait till the 60’s before Fizeau and Foucault showed us how to determine its exact value."}]}
{"messages": [{"role": "assistant", "content": "It has been long known that light has a finite velocity, but we had to wait till the 60’s before Fizeau and Foucault showed us how to determine its exact value. The methods introduced by them have been recently applied by Cornu, Newcomb, and Michelson, and the resulting value is slightly less than three hundred thousand metres per second. Combining this with the constant of aberration, the distance of the sun can be determined. It is wonderful how these vastly different methods agree in the resulting mean distance. At the beginning of the century it stood roughly at ninety-five million miles; this has been reduced to ninety-three million nine hundred and sixty-five thousand miles. The extreme difference between the old and new values of the solar parallax, two-fifths of a second of arc, is represented by the apparent breadth of a human hair viewed at a distance of about one hundred and twenty-five feet."}]}
{"messages": [{"role": "assistant", "content": "The extreme difference between the old and new values of the solar parallax, two-fifths of a second of arc, is represented by the apparent breadth of a human hair viewed at a distance of about one hundred and twenty-five feet. Knowing the distance of the sun, the way is open to us to determine, by a method suggested by Galileo, the distances of those stars which occupy a different position among their fellows, as seen from opposite points in the earth’s orbit round the sun, points one hundred and eighty-six million miles apart. We now know the distances of many such stars, Bessel having determined the first in 1838. The nearest star to us, so far as we know, is Centauri, the light of which takes four and a half years to reach us. Not many years ago Pritchard applied photography to this branch of inquiry; we may, therefore, expect a still more rapid progress in the future. With regard to masses."}]}
{"messages": [{"role": "assistant", "content": "With regard to masses. We naturally must first know that of the earth; having its size, if we can determine its density, the rest follows. The problem of determining the mean density of the earth occupied the minds of many workers during the nineteenth century. Newton (about 1728) pointed out how it could be deduced by observing the deviation from the vertical of a plumb-line suspended near a large mass of matter—a mountain, the volume and density of which could be previously determined. This method, which is very laborious and requires the greatest skill and most delicate instruments, has been employed several times, by Bouguer and Condamine, in 1738, at Chimborazo; Maskelyne, in 1774, at Schehallien in Scotland; and James, at Arthur’s Seat, near Edinburgh. At the beginning of the century another method was introduced by Cavendish."}]}
{"messages": [{"role": "assistant", "content": "At the beginning of the century another method was introduced by Cavendish. This consists in measuring the attraction of two large spheres of known size and mass, such as two balls of lead on two very small and light spheres, by means of a torsion balance constructed by Mitchell for this purpose. The most recent determination by this method, and one which is considered to give us perhaps the most accurate value, is that which is due to the skill and ingenuity of Professor Boys. His improvement consisted in constructing a most delicate torsion balance; the attracted spheres consisted of small gold balls suspended by a quartz fibre carrying a mirror to indicate the amount of twist. The whole instrument was quite small, and could easily be protected from air currents and changes of temperature, while the use of the quartz fibres reduced to a minimum one of the greatest difficulties of the Cavendish experiment. The value of the mean density of the earth is now considered to be 5.6, which means that if we have a globe of water exactly the same size as our own earth, the real earth would weigh just 5.6 times this globe of water."}]}
{"messages": [{"role": "assistant", "content": "The value of the mean density of the earth is now considered to be 5.6, which means that if we have a globe of water exactly the same size as our own earth, the real earth would weigh just 5.6 times this globe of water. The earth’s weight, in tons, does not convey much idea, but that it is six thousand trillions may interest the curious. This determination has enabled the masses of the sun, moon, planets and satellites, and many sidereal systems to be accurately known in relation to the mass of the earth. SOME ACHIEVEMENTS OF MATHEMATICAL ANALYSIS \nUranus, a planet unknown to the ancients, was discovered by its movement among the stars by William Herschel in 1781. It was not until 1846 that another major planet was added to the solar system, and this discovery was one of the sensations of the century. The story of the independent discovery of Neptune by Adams and Le Verrier, who were both driven to the conclusion that certain apparent regularities in the motion of Uranus were due to the attraction of another body travelling on an orbit outside it, has been often told."}]}
{"messages": [{"role": "assistant", "content": "The story of the independent discovery of Neptune by Adams and Le Verrier, who were both driven to the conclusion that certain apparent regularities in the motion of Uranus were due to the attraction of another body travelling on an orbit outside it, has been often told. The subsequent discovery of the external body not far from the place at which their mathematical analysis had led them to believe it would be seen, will forever be regarded as a fine triumph of the human intellect. But the results of the inquiries which now concern us are generally of not so sensational a character, although they lie at the root of our knowledge of celestial motions. They more often take the shape of tables and discussions relating to the movements of the bodies which make up our solar system. Gauss may be said to have led the way during the nineteenth century by his _Theoria molus corporum coelestium solem ambientium_. This was a worthy sequel to the _Méchanique Céleste_, in which work, towards the end of the eighteenth century, Laplace had enshrined all that was known on the planetary results of gravitation."}]}
{"messages": [{"role": "assistant", "content": "This was a worthy sequel to the _Méchanique Céleste_, in which work, towards the end of the eighteenth century, Laplace had enshrined all that was known on the planetary results of gravitation. In later years Le Verrier and Newcomb have been among the chief workers on whom the mantle of such distinguished predecessors has fallen. From them the planet and satellite tables now in use have been derived. But the motion of our own satellite, the moon, has had fascinations for other analysts besides those we have named. The problem, indeed, of the moon’s motion is one of the most difficult, and has taxed the ingenuity of astronomers from an early date. Even at the present day it is impossible to predict the exact position of the moon at any one moment owing to inequalities and perturbations, the exact varying values of which are not known."}]}
{"messages": [{"role": "assistant", "content": "Even at the present day it is impossible to predict the exact position of the moon at any one moment owing to inequalities and perturbations, the exact varying values of which are not known. The two most important theories of the motion of the moon completed towards the middle of the century were due to Hansen and Delaunay. The former’s appeared in 1838, the lunar tables being published later (1857), while the latter’s was published in 1860. Hansen’s theory had for its chief object the formation of tables; to avoid the inconvenience of using in his calculations series which slowly converge, he inserted numerical values throughout. In Hansen’s solution the problem is one actually presented by nature, allowance being made for every known cause of disturbance. There is one disadvantage, namely, that should observations demand a change in any of the constants used, there is no means of making any correction in the results."}]}
{"messages": [{"role": "assistant", "content": "There is one disadvantage, namely, that should observations demand a change in any of the constants used, there is no means of making any correction in the results. Delaunay’s theory surmounted this difficulty, but at the expense of still greater inconvenience for making an ephemeris. The slow convergence of certain series involved an immense amount of labor to give sufficiently approximate results. More recently, as the century was closing, Dr. Brown took up the subject and made a fresh attempt to calculate the motion of our satellite. It may be stated that he adopts all Delaunay’s modifications of the problem and works them out algebraically; but there are many technical differences which it would be out of place to mention here."}]}
{"messages": [{"role": "assistant", "content": "It may be stated that he adopts all Delaunay’s modifications of the problem and works them out algebraically; but there are many technical differences which it would be out of place to mention here. Enough has been stated to show that there is not likely to be any breach of continuity in the treatment of this most important problem. Another attack on the moon, and, incidentally, its motion, has recently been made by another analyst, Professor George Darwin; grappling with all the consequences of tidal friction, he has been able to present to us the past and future history of our satellite. Beginning as a part of the material congeries from which subsequently some fifty million years ago both earth and moon, as separate bodies, were formed, it has ever since been extending its orbit, and so retreating farther away from its centre of motion, while the period of the earth’s rotation has been increasing at the same time, from a possible period of some three hours when the moon was born, to one of one thousand four hundred hours when the day and month will be equal, something like one hundred and fifty million years being required for the process. STELLAR EVOLUTION \nIt was only in the 80’s, after thousands of observations of the spectra of stars, nebulæ, and comets had been secured, that the full meaning of the revelations of the spectroscope began to dawn upon the world. Before the introduction of spectrum analysis all stars were supposed to be suns, and the only difference recognized among them was one of brilliancy and the variation of brilliancy in the case of some of them."}]}
{"messages": [{"role": "assistant", "content": "Before the introduction of spectrum analysis all stars were supposed to be suns, and the only difference recognized among them was one of brilliancy and the variation of brilliancy in the case of some of them. It ultimately came out that great classes might be recognized by the differences of their spectra, which were ultimately traced to differences in their chemistry and in their temperature, as determined by the extension of the spectra in the ultra-violet, the whiter stars being hotter than the red ones, as a white-hot poker is hotter than a red-hot poker. Next there was evidence to show that a large proportion of the stars were not stars at all like the sun, but swarms of meteorites; and in this way the mysterious new stars which appear from time to time in the heavens, and a large number of variable stars, were explained as arising from collisions among such swarms. The inquiry which dealt with the spectroscopic results, having thus introduced the ideas of meteor swarms and collisions to explain many stellar phenomena, went further and showed that the various chemical changes observed in passing from star to star might also be explained by supposing the whole stellar constitution to arise from cool meteoritic swarms represented by nebulæ, the changes up to a certain point being explained by a rise of temperature due to condensation towards a centre. Here the new view was opposed to that of Laplace, advanced during the last century, that the stars were produced by condensation and cooling; but Kelvin had shown, before the new view was enunciated, that Laplace’s view was contrary to thermodynamics, a branch of science which had developed since Laplace published his famous _Exposition du Système du Monde_. After all the meteorites in the parent swarm had been condensed into the central gaseous mass, that mass had to cool."}]}
{"messages": [{"role": "assistant", "content": "After all the meteorites in the parent swarm had been condensed into the central gaseous mass, that mass had to cool. So that we had in the heavens not only stars more or less meteoritic in structure, of _rising_ temperature, but stars chiefly gaseous, of falling temperature. It was obvious that representatives of both these classes of stars might have nearly the same mean effective temperature, and therefore more or less the same spectrum. A minute inquiry entirely justified these conclusions. So far had the detailed chemistry of the stars been carried in the latter years of the century that the question of stellar evolution gave rise to that of inorganic evolution generally, the sequence in the phenomena of which can only be studied in the stars, for laboratory work without stint has shown that in them we have celestial furnaces, the heat of which transcends that of our most powerful electric sparks. In this way astronomy is paying the debt she owes to chemistry."}]}
{"messages": [{"role": "assistant", "content": "In this way astronomy is paying the debt she owes to chemistry. THE SUN AND HIS SYSTEM \nAlthough the outer confines of space have, as we have seen, been compelled to bring their tribute of new knowledge by means of the penetrating power possessed by modern telescopes, and the cameras and spectroscopes attached to them, the study of the _near_ has by no means been neglected, and for the reason that in astronomy especially we must content ourselves in the case of the more distant bodies by surmising what happens in them from the facts gathered in the region where alone detailed observations are possible. Thus what we can learn about the sun helps to explain what we discern much more dimly in the case of stars; a study of the moon’s face we are compelled to take as showing us the possibilities relating to the surface condition of other satellites so far removed from us that they only appear as points of light. To begin, then, with the sun. Where a volume might be written, a few words must suffice. I have already stated that at the beginning of the nineteenth century the prevailing opinion was that it was a habitable globe."}]}
{"messages": [{"role": "assistant", "content": "I have already stated that at the beginning of the nineteenth century the prevailing opinion was that it was a habitable globe. It was limited to the fiery ball we see. At the end of the century it is a body of the fiercest heat, and the ball we see is only a central portion of a huge and terribly interesting mechanism, the outer portions of which heave and throb every eleven years. Spots, prominences, corona, everything feels this throbbing. Although the discovery of spots on the sun was among Galileo’s first achievements, it was reserved for the last half of the nineteenth century to demonstrate their almost perfect periodicity. Thanks to the labors of Schwabe, Wolf, Carrington, and De la Rue, Stewart, and Loewy, we now know that every eleven years the spots wax and wane; Tacchini and Ricco, during the last thirty years, have proved that the prominences follow suit, and the fact that the corona also obeys the same law was established during the American eclipse of 1878."}]}
{"messages": [{"role": "assistant", "content": "Thanks to the labors of Schwabe, Wolf, Carrington, and De la Rue, Stewart, and Loewy, we now know that every eleven years the spots wax and wane; Tacchini and Ricco, during the last thirty years, have proved that the prominences follow suit, and the fact that the corona also obeys the same law was established during the American eclipse of 1878. The study of solar physics consists in watching and recording the thermal, chemical, and other changes which accompany this period. Some of these effects can be best studied during those times when the ball itself is covered by the moon in an eclipse. Then the outer portions of the sun are revealed in all their beauty and majesty, and all the world goes to see. But it is the quiet daily work in the laboratory which has enabled us to study the sun’s place in relation to the other stars, and so to found a chemical classification of all the stars that shine. From the sun we may pass to his system, and first consider the nearest body to us—the moon."}]}
{"messages": [{"role": "assistant", "content": "From the sun we may pass to his system, and first consider the nearest body to us—the moon. While some astronomers have been discussing the movements and evolution of our satellite, others have been engaged upon maps of its surface, upon questions dealing with a lunar atmosphere, or a study of the origin of the present conformations and of possible changes. The science of selenology may be said to have been founded by Schröter at the beginning of the century, but it required the application of photography in later years to put it on a firm basis. Maps of the moon have been prepared by Lohrmann, Beer and Mädler, and Schmidt, the latter showing the positions of more than thirty thousand craters. Very erroneous notions are held by some as to what we may hope to do in the examination of the moon’s surface by a powerful telescope. A power of a thousand enables us to see it as if we were looking at York from London."}]}
{"messages": [{"role": "assistant", "content": "A power of a thousand enables us to see it as if we were looking at York from London. It is recorded that Lassell once said that with his largest reflector in a “fit” of the finest definition he thought he might be able to detect whether a carpet as large as Lincoln’s Inn Fields was round or square. Under these circumstances, then, we may well understand that the question of changes on the surface has been raised from time to time never to be absolutely settled one way or the other. By many the existence of an atmosphere is denied, and this is a condition which would negative changes, anything like the geological changes brought about on the surface of the earth, but the idea is now held by many that there is still an atmosphere, though of great tenuity. The last few years of the century were rendered memorable from the lunar point of view by the publication and minute study of a most admirable series of photographs of the moon obtained by the great equatorial Coudé of the Paris Observatory by Loewy and Puiseaux. One of the chief points aimed at has been to determine the sequence of the various events represented by the rills, craters, and walled plains, the mountain ranges and seas."}]}
{"messages": [{"role": "assistant", "content": "One of the chief points aimed at has been to determine the sequence of the various events represented by the rills, craters, and walled plains, the mountain ranges and seas. This work is still in progress, the fourth part of the atlas being published in 1900; but enough has already appeared to indicate that the results of the inquiry when completed will be of the most important kind. The authors have already come to the conclusion that the lunar and terrestrial sea-bottoms much resemble each other, inasmuch as both have convex surfaces. The lunar seas began by sinking of vast regions; the formidable volcanic eruptions of which the moon has been the scene have taken place in times equivalent to those labelled “recent” in geological parlance. There is evidence that the axis of the moon has undergone great displacements, and four great periods of change have been made out. Finally they state that there is serious ground to believe that there is an atmosphere of some sort remaining."}]}
{"messages": [{"role": "assistant", "content": "Finally they state that there is serious ground to believe that there is an atmosphere of some sort remaining. It may readily be understood that with each increase of optical power new satellites of the various planets have been discovered. Soon after the discovery of Neptune a satellite was noted by Lassell. In 1846 both he and the eagle-eyed observer Dawes independently discovered another satellite (Hyperion) of Saturn. Lassell was rewarded in the next year by the discovery of two more satellites of Uranus; but, strangest observation of all, in 1877 Hall discovered at Washington two satellites of Mars some six or seven miles only in diameter, one of them revolving round the planet in seven and one-half hours at a distance of less than four thousand miles. As the day on Mars is not far different in duration from our own, this tiny satellite must rise in the west and south three times a day!"}]}
{"messages": [{"role": "assistant", "content": "As the day on Mars is not far different in duration from our own, this tiny satellite must rise in the west and south three times a day! Wonderful as this discovery was, it is certainly not less wonderful when we consider it in connection with a passage in _Gulliver’s Travels_, so true is it that truth is stranger than fiction. Swift, in his satirical reference to the inhabitants of Laputa, writes: “They have likewise discovered two lesser stars, or satellites, which revolve round Mars, whereof the innermost is distant from the centre of the primary planet exactly three of his diameters and the outermost five; the former revolves in the space of ten hours; and the latter in twenty-one and a half.” \nThe last discovery of this kind has been that of an inner satellite of Jupiter by Barnard in 1892. The planets from Mercury to Saturn were known to the ancients. I have already referred to the discovery of Uranus by Herschel’s giant telescope, not long before the nineteenth century was born, and of Neptune, by analysis, towards the end of the first half of the century. With regard to what modern observations have done in regard to their physical appearance, the first place in general interest must be given to Saturn and Mars."}]}
{"messages": [{"role": "assistant", "content": "With regard to what modern observations have done in regard to their physical appearance, the first place in general interest must be given to Saturn and Mars. Saturn has always been regarded as the most interesting of the planetary family on account of its unique rings. Many subdivisions of the rings, and a dusky ring, first seen by Dawes and Bond, have been discovered during the last sixty years. The meteoritic nature of the rings was suggested by Clerk Maxwell in 1857, and Keeler’s demonstration of the truth of this view by means of the spectroscope, a few years ago, was brilliant in conception and execution. But during the last half of the century the interest centred in Mars has been gradually increasing. The drawings made during the opposition of 1862, when compared with those made by Beer and Mädler (1830–40), made it perfectly clear that in this planet we had to deal with one strangely like our own in many respects."}]}
{"messages": [{"role": "assistant", "content": "The drawings made during the opposition of 1862, when compared with those made by Beer and Mädler (1830–40), made it perfectly clear that in this planet we had to deal with one strangely like our own in many respects. There were obviously land and water surfaces; the snow at the poles melted in the summer-time; clouds were seen forming from time to time, and the changing tones of the water surfaces suggested fine and rough weather. Afterwards came the revelation of the hawk-eyed Schiaparelli, beginning in the year 1877, and his wonderful map of the planet’s surface. The land surfaces, instead of being unbroken, were cut up, as an English farm is cut up by hedges; straight lines of different breadths and tints crossed the land surfaces in all directions, and at times some of them appeared double. Schiaparelli naturally concluded that they were rivers—water channels—and being an Italian he used the appropriate word _canali_. This, unfortunately, as it turned out, was translated _canals_."}]}
{"messages": [{"role": "assistant", "content": "This, unfortunately, as it turned out, was translated _canals_. Now canals are dug, _ergo_ there were diggers. From this the demonstration, not of the habitability, but of the actual habitation, of Mars was a small step, and the best way of signalling to newly found kinsmen across some thirty millions of miles of space was discussed. The world of science owes a debt of gratitude to Mr. Percival Lowell for having taken out to the pure air and low latitude of Arizona an eighteen-inch telescope for the sole purpose of accumulating facts tending to throw light upon this newly raised question. This he did in 1894."}]}
{"messages": [{"role": "assistant", "content": "This he did in 1894. Schiaparelli has continued his magnificent observations through each opposition when the planet is most favorably situated for observation, and since 1896 Signor Cerulli, armed with a fifteen-inch Cooke, in the fine climate of Italy, has joined in the inquiry, so that facts are now being rapidly accumulated. It has been stated that markings similar to the strange so-called “canals” on Mars are to be seen on Mercury, Venus, and even on the satellites of Jupiter. Mr. Percival Lowell does not hesitate to proclaim himself in favor of their being due, _in Mars_, to an intelligent system of irrigation. Signor Cerulli claims that _wherever seen_ they are mere optical effects."}]}
{"messages": [{"role": "assistant", "content": "Signor Cerulli claims that _wherever seen_ they are mere optical effects. We may be well content to leave to the twentieth century a general agreement on this interesting subject. Finally, in our survey of our own system, come comets and meteor swarms. One of the most fruitful discoveries of the century, that comets are meteor swarms, we owe to the genius of Schiaparelli, A. H. Newton, and other workers on those tiny celestial messengers which give rise to the phenomena of “falling” or “shooting” stars."}]}
{"messages": [{"role": "assistant", "content": "Newton, and other workers on those tiny celestial messengers which give rise to the phenomena of “falling” or “shooting” stars. The magnificent displays of 1799, 1833, 1866, and, alas! that which failed to come in 1899, we now know must be associated with Tempel’s Comet. This is by no means the only case so far established; the connection will in the future be closer still when the orbits of the various swarms observed throughout the year shall be better known. Comets which attract public attention by their brightness and grandeur of form are rather rare, and, in fact, only twenty-five of such have been seen since 1800. We have, however, with the great advance in instrumental equipment, been able to discover many which are scarcely visible to the naked eye, and this has swollen the number of comets very considerably."}]}
{"messages": [{"role": "assistant", "content": "We have, however, with the great advance in instrumental equipment, been able to discover many which are scarcely visible to the naked eye, and this has swollen the number of comets very considerably. In the seventeenth century we find that only thirty-two were observed, while in the eighteenth this number was more than doubled (seventy-two). In the nineteenth century more than three hundred were placed on record, which is practically more than four times the number seen in the eighteenth. The last great comet visible any considerable time was that discovered by Donati in 1858, and so carefully observed by Bond. It is unfortunate that since the importance, in so many directions, of spectroscopic observations of comets has been recognized they have been conspicuous by their absence. THE CONNECTION BETWEEN SOLAR AND TERRESTRIAL WEATHER \nEverybody agrees that all the energy utilized on this planet of ours, with the single exception of that supplied by the tides, comes from the sun."}]}
{"messages": [{"role": "assistant", "content": "THE CONNECTION BETWEEN SOLAR AND TERRESTRIAL WEATHER \nEverybody agrees that all the energy utilized on this planet of ours, with the single exception of that supplied by the tides, comes from the sun. We are all familiar with the changes due to the earth’s daily rotation bringing us now on the side of our planet illuminated by the sun, then plunging us into darkness; that changes of season must necessarily follow from the earth’s yearly journey round the sun is universally recognized. On the other hand, it is a modern idea that those solar phenomena which prove to us considerable changes of temperature in the sun itself, may, and indeed should, be echoed by changes on our planet, giving us thereby an eleven-year period to be considered, as well as a year and a day. This response of the earth to solar changes was first observed in the continuous records of those instruments which register for us the earth’s magnetism at any one place. The magnetic effects were strongest when there were more spots, taking them as indicators of solar changes. Lamont first (without knowing it) made this out, at the beginning of the latter half of the century (1851), from the Göttingen observations of the daily range of the declination needle."}]}
{"messages": [{"role": "assistant", "content": "Lamont first (without knowing it) made this out, at the beginning of the latter half of the century (1851), from the Göttingen observations of the daily range of the declination needle. Sabine the next year not only announced the same cycle in the violence of the “magnetic storms” observed at Toronto, but at once attributed them to solar influence, the two cycles running concurrently. It is now universally recognized that terrestrial magnetic effects, including auroræ, minutely echo the solar changes. The eleven-year period is not one to be neglected. Next comes the inquiry in relation to meteorology. Sir William Herschel, in the first year of the century, when there were practically neither sun-spot nor rainfall observations available, did not hesitate to attack the question whether the price of wheat was affected by the many-or-few-spot solar condition."}]}
{"messages": [{"role": "assistant", "content": "Sir William Herschel, in the first year of the century, when there were practically neither sun-spot nor rainfall observations available, did not hesitate to attack the question whether the price of wheat was affected by the many-or-few-spot solar condition. He found the price to be high when the sun was spotless, and _vice versa_. By 1872, however, we had both rainfall and sun-spot observations, and the cycle of the latter had been made out. Meldrum, the most distinguished meteorologist living at the time, and others, pronounced that the rainfall was greatest at sun-spot maximum, and, further, that the greatest number of cyclones occurred in the East and West Indies at such times. This result with regard to rainfall was not generally accepted, but Chambers showed shortly afterwards an undoubted connection between the cycles of solar spots and barometric pressure in the Indian area. By means of a study of the widened lines observed in sun spots an attempt has been recently made to study the temperature, history of the sun since about 1877, and the years of mean temperature and when the heat was in excess (+) and defect (-) made out, have been as follows: \n  Heat   condition   mean   +   mean   −   mean   +     mean    −     mean   Years       1869       1876       1881        1886–87       1891–92                  1870–75     1877–80    1882–86       1881–91  1892 \nHaving these solar data, the next thing to do was to study the Indian rainfall during the southwest monsoon for the years 1877–1886, the object being to endeavor to ascertain if the + and − temperature pulses in the sun were echoed by + and − pulses of rainfall."}]}
{"messages": [{"role": "assistant", "content": "By means of a study of the widened lines observed in sun spots an attempt has been recently made to study the temperature, history of the sun since about 1877, and the years of mean temperature and when the heat was in excess (+) and defect (-) made out, have been as follows: \n  Heat   condition   mean   +   mean   −   mean   +     mean    −     mean   Years       1869       1876       1881        1886–87       1891–92                  1870–75     1877–80    1882–86       1881–91  1892 \nHaving these solar data, the next thing to do was to study the Indian rainfall during the southwest monsoon for the years 1877–1886, the object being to endeavor to ascertain if the + and − temperature pulses in the sun were echoed by + and − pulses of rainfall. The Indian rainfall was taken first because in the tropics the phenomena are known to be the simplest. It was found that in many parts of India the + and − conditions of solar temperature were accompanied by + and − pulses, producing pressure changes and heavy rains in the Indian Ocean and the surrounding land. These occurred generally in the first year following the mean condition, that is, in 1877–78 and 1882–83. The rainfalls at Mauritius, Cape Town, and Batavia were next collated to see if the pulses felt in India were traceable in other regions surrounding the Indian Ocean to the south and east. This was found to be the case."}]}
{"messages": [{"role": "assistant", "content": "This was found to be the case. A wider inquiry was followed, we are told, with equal success, so that we are justified in hoping that the question of the dependence of terrestrial upon solar weather has made a step in advance. But just as the general public and practical men took little heed of the connection between sun spots and magnetism until experience taught them that telegraphic messages often could not “get through” when there were many sun spots, so the same public will not consider the connection in regard to meteorology unless the forecasting of droughts and famines be possible. The recent work suggests that, if the recent advances in solar physics be considered, the inquiries regarding rainfall may be placed on a firmer basis than they could possibly have had in 1872, and that such forecastings may become possible. What was looked for in 1872 was a change in the quantity of rain at maximum sun spots only, the idea being that there might be an effective change of solar temperature, either in excess or defect, at such times and that there would be a gradual and continuous variation from maximum to maximum. We see that the rainfalls referred to above justify the conclusions derived from the recent work that two effects ought to be expected in a sun-spot cycle instead of one."}]}
{"messages": [{"role": "assistant", "content": "We see that the rainfalls referred to above justify the conclusions derived from the recent work that two effects ought to be expected in a sun-spot cycle instead of one. There was excess of rainfall, not only near the sun-spot maximum, but near the minimum. If the authors of this communication to which I refer are right, then droughts and famines occur in India because the rain pulses, which are associated with the solar-heat pulses, are of short duration. When they cease the quantity of rain which falls in the Indian area is not sufficient, without water storage, for the purposes of agriculture; they are followed, therefore, by droughts, and at times subsequently by famines. They divide the period 1877—89 as under: \n\n                           { 1877. Rain from − pulse        { 1878."}]}
{"messages": [{"role": "assistant", "content": "Rain from − pulse        { 1878. { 1879 (part). { 1879 (part). No rain pulse            { 1880 (central year). { 1881 (part). { 1881 (part)."}]}
{"messages": [{"role": "assistant", "content": "{ 1881 (part). { 1882. Rain from + pulse        { 1883. { 1884 (part). { 1884 (part). { 1885 }   No rain pulse            { 1886 } (central year)."}]}
{"messages": [{"role": "assistant", "content": "{ 1885 }   No rain pulse            { 1886 } (central year). { 1887 (part). { 1887 (part). Rain from − pulse        { 1888. { 1889. Their statement is based on the fact that all the famines which have devastated India for the last seventy years have occurred at intervals of eleven years, or thereabouts, working backward and forward from the central years 1880 and 1885–86 in the above table, the middle years, that is, between the pulses."}]}
{"messages": [{"role": "assistant", "content": "Their statement is based on the fact that all the famines which have devastated India for the last seventy years have occurred at intervals of eleven years, or thereabouts, working backward and forward from the central years 1880 and 1885–86 in the above table, the middle years, that is, between the pulses. Mr. Willcocks, in a paper read at the Meteorological Congress at Chicago, remarked that “famines in India are generally years of low flood in Egypt.” \nIt is now pointed out that the highest Niles follow the years of the + and − pulses, as does the highest rainfall in the Indian area. Even if these results, which were communicated to the Royal Society of London five weeks before the end of the century, be confirmed, it may be pointed out that Sir William Herschel’s suggestion of 1801 will have required a whole century for its fulfilment, so slowly do those branches of science move which have not already led to some practical development. NORMAN LOCKYER. PHILOSOPHY \n\nIt is a natural illusion that makes us think of each century as exhibiting the continuous development of one tendency of mind through a series of stages whose differences are only of secondary importance, and, on the other hand, to regard the steps from one century to another as corresponding to some marked transition of thought, as if the world had been suddenly precipitated into a new sphere of existence."}]}
{"messages": [{"role": "assistant", "content": "PHILOSOPHY \n\nIt is a natural illusion that makes us think of each century as exhibiting the continuous development of one tendency of mind through a series of stages whose differences are only of secondary importance, and, on the other hand, to regard the steps from one century to another as corresponding to some marked transition of thought, as if the world had been suddenly precipitated into a new sphere of existence. For some purposes a rough generalization of this kind, that breaks at stated intervals the continuity of time, may, perhaps, be convenient. When, however, we begin to look at things more closely, we discover that it is impossible thus to cut through the historical connection of events, as it were, “with a hatchet.” We discover, for example, that the characteristics of the eighteenth century were strongly marked only in one period of it; and that what we call the spirit of the nineteenth century was born some time before the year 1800, and has never quite prevailed over other tendencies. At the same time, there is an important difference indicated by these two loosely used names, and as it is always easier to define things by contrast, it may help us to make our subject more definite to consider what they mean. I \nIt is too late now to “abuse the eighteenth century,” which had its good and evil, like other periods. It is commonly conceived as the era of individualism and analysis, the era of logical enlightenment and sceptical criticism; and, again, as the era of liberation from groundless superstitions and fictitious claims of authority; the era in which mankind seemed for the first time to throw off the weight of the past and to enter without fear upon the enjoyment of their earthly heritage."}]}
{"messages": [{"role": "assistant", "content": "It is commonly conceived as the era of individualism and analysis, the era of logical enlightenment and sceptical criticism; and, again, as the era of liberation from groundless superstitions and fictitious claims of authority; the era in which mankind seemed for the first time to throw off the weight of the past and to enter without fear upon the enjoyment of their earthly heritage. The science of Newton had given the last blow to the astronomy that made the earth the centre of the universe. It had undermined and discredited the simple theology that explained the whole material world as a cosmos arranged for the supply of human needs. At the same time, the progress of biology was bringing man to a consciousness that as a physical being he is only _primus inter pares_ in the animal kingdom, and the decay of religious belief was making him realize his finitude, the limits of his natural existence, as, perhaps, he had never done before, at least never since the beginning of the Christian era. Earth seemed to be disconnected from heaven, and the human race thrown upon its own resources. By the new enlightenment all powers, ecclesiastical or political, were stripped of the mysterious sanctity that had once invested them."}]}
{"messages": [{"role": "assistant", "content": "By the new enlightenment all powers, ecclesiastical or political, were stripped of the mysterious sanctity that had once invested them. “The nimbus was taken away from the heads of the gods and rulers of the world.” Every authority that claimed man’s homage was weighed in the scales of the understanding, and, so weighed, every such authority was found wanting. The State had come to be regarded as only a collection of individuals who had agreed to live together under a ruler deriving all his claims from their consent, and invested with no divine right to their allegiance. The Church was no longer a sacred institution governed by priests who held their commission directly from God, but only a sort of spiritual police agency, an ally of the State in the restraint of vice and crime, or, at best, in Protestant countries, a society for mutual improvement. Men were “free and equal,” each standing face to face with his fellows, admitting no superiority or superstition of hero-worship in regard to any one of them. And the Deity, if his existence were not denied, tended to become a mere “Supreme Being,” who was removed to such a distance from mankind that he could hardly be reached by their reverence, still less by their love."}]}
{"messages": [{"role": "assistant", "content": "And the Deity, if his existence were not denied, tended to become a mere “Supreme Being,” who was removed to such a distance from mankind that he could hardly be reached by their reverence, still less by their love. At the same time, the influences which, in one point of view, seemed to limit and narrow human existence, in another point of view tended to liberate and enlarge it. If they excluded the idea of the infinite from man’s life, they emancipated him from many degrading superstitions, which in an earlier age had held him “all his lifetime subject to bondage.” And as the pressure from above was lightened the individual seemed to become master of himself and of his destiny. If the king could no longer say, “_L’Etat c’est moi_,” the rights of the subject were vindicated; if the authority of the Church was weakened, the bonds of free inquiry were broken; if imagination ceased to fill men with the awe and wonder of higher powers, the way was opened up for scientific and industrial development; if God was regarded as unknowable, “the proper study of mankind was man,” and that study could now be pursued without fear or hinderance. Poetry and religion might be impoverished, the sense of the binding force of social relations might be weakened, but interest in the bettering of man’s earthly condition was awakened, and with it came a new desire for justice to all, a new intolerance of human suffering, and a new demand that the lot of the class “which is most numerous and poor” should be made less wretched and insecure, and, towards the end of the century, a new turn was given to its leading thought, for an effort was made to discover in the nature of the individual himself the equivalent of those universal powers which the enlightenment had banished from the external world and from the life of society. Rousseau carried individualism to an extreme point, at which it became its own correction, and taught men to find _within_ their own souls the infinite which they could no longer discover _without_."}]}
{"messages": [{"role": "assistant", "content": "Rousseau carried individualism to an extreme point, at which it became its own correction, and taught men to find _within_ their own souls the infinite which they could no longer discover _without_. Rejecting in the first instance all social conventions as unjust limitations of the natural man, and adopting the prevailing theory of the time, that the State is only the product of a contract between independent persons, he yet discovered in the individual thus liberated from all external pressure a “common reason,” and “a general will,” which could reorganize his life and bind him to his fellow-men and to God. This great idea, which appears in Rousseau rather as a stroke of insight, an intuition of genius—lifting him above his first thoughts and insensibly changing their meaning—was grasped by Kant as the principle of a new philosophy and worked out in a comprehensive system that dealt with all the great problems of thought and life. Kant, indeed, seemed, like Rousseau, to begin on the plane of eighteenth-century individualism, but, influenced as he was by the philosophy of Leibnitz, he from the first conceived the individual as in himself universal; or, to speak more exactly, as having a universal principle realized in him. Thus, though in one aspect of his being man is a finite object among other objects, confined within limits of space and time, and forming only a link in the chain of natural causation, in another aspect of it, as a conscious self, he is emancipated from all these limitations. For—such is Kant’s argument—a knowing subject, for whom the whole finite world, including his own finite existence, is an object of knowledge, cannot himself be comprehended in that world or limited by any of its conditions."}]}
{"messages": [{"role": "assistant", "content": "For—such is Kant’s argument—a knowing subject, for whom the whole finite world, including his own finite existence, is an object of knowledge, cannot himself be comprehended in that world or limited by any of its conditions. As there can be no world of objects except for a self, it is impossible that such a self should be merely one of these objects. Thus, as knowing, or capable of knowing, all things, man cannot be identified with any of them; or if, from one point of view, as an individual, he is so identified, yet he has within him a universal principle that carries him beyond the limits of his individuality. And this contrast shows itself also in his practical life. For if as an object he appears to be but an animal organism, moved by the impressions of pleasure and pain which he receives from other objects, yet in his inner moral life man is revealed to himself as a self-determining subject, emancipated from all sensuous motives and from the necessity of nature which they bring with them, and conscious of subordination only to the law of duty, which is the law of his own reason. And that law, in spite of every pressure of circumstance from without, and of every impulse of passion from within, he knows that he ought to obey, and therefore he knows that he _can_ obey it."}]}
{"messages": [{"role": "assistant", "content": "And that law, in spite of every pressure of circumstance from without, and of every impulse of passion from within, he knows that he ought to obey, and therefore he knows that he _can_ obey it. Thus, in Kant’s theory, the two extreme views of humanity, as natural and as spiritual, as limited to a finite individuality, hemmed in by necessities on every side, and yet as possessing a universal capacity of knowing, and an absolute power of self-determination, these two views are presented in sharp antithesis, and at the same time held together as different aspects of one life. In fact, we have here, as it were, compressed into a nutshell, the result of the whole history of eighteenth-century individualism, which began by depressing man and ended by exalting him; which, with one of its voices, seemed to reduce him to the level of an animal, a mere part of the partial world, a transitory phenomenal existence among other phenomena; and then, with its other voice, proceeded to recognize him as a member of the intelligible world, a “spectator of all time and existence,” and gifted with the absolute freedom of a will which could be determined by nothing but itself. “The solitary,” says Aristotle, “must be either a god or a beast,” and the eighteenth century, in its conception of the individual, seemed to oscillate between the one and the other till Kant, awaking to the impossibility of omitting either aspect of his being, demanded that he should be conceived as both at once. Kant thus set the problem of the future; and if he did not solve it, he at least showed the futility of any narrow or one-sided solution and the direction in which an adequate solution could alone be sought. In short, Kant asked the question to which the nineteenth century, in all its philosophical reflection, has been striving to find an answer."}]}
{"messages": [{"role": "assistant", "content": "In short, Kant asked the question to which the nineteenth century, in all its philosophical reflection, has been striving to find an answer. For in philosophy, as in other departments of knowledge, the work of the nineteenth century has been one of mediation and reconciliation. It has been an endeavor to break down the sharp antithesis of philosophical and scientific theories that was characteristic of an earlier time. In the writings of the greatest thinkers, the oppositions of materialism and spiritualism, of sensationalism and idealism, of empiricism and _a priori_ speculation, of individualism and socialism, all the great oppositions of theoretical and practical philosophy, which formerly were held to be absolute and irreconcilable, have been modified, restated, reduced to the _relative_ antagonism of the different aspects of one truth. The great controversies of the past have thus passed into a new phase, in which absolute statements _pro_ and _con_ have become, as it were, antiquated; and the question is no longer whether a particular doctrine or its opposite is true, but what are the elements of truth and error in each of them, and how we can attain to a comprehensive view of things, in which justice is done to both. And if it be asked, what are the principles or ideas that have suggested this reconciling work, and have been the guides of the greatest scientific or philosophic writers in attempting to achieve it, I think the answer must be that they are _the idea of organic unity_, and, as implied in that, _the idea of development_."}]}
{"messages": [{"role": "assistant", "content": "And if it be asked, what are the principles or ideas that have suggested this reconciling work, and have been the guides of the greatest scientific or philosophic writers in attempting to achieve it, I think the answer must be that they are _the idea of organic unity_, and, as implied in that, _the idea of development_. Goethe and Hegel, in Germany; Comte, in France; Darwin and Spencer, in England, are writers who almost span the whole range of difference in modern thought; but they, and a multitude of others in every department of study, have been inspired by the ideas of organism and development. And they have all used them somewhat in the same way to turn the edge of the old controversial weapons, or to lift thought above the “yes” and “no” of opposing dogmatisms. It is true that the definitions or interpretations of the ideas of organism and development given by these writers are very different, and often, indeed, so sharply opposed that they seem to bring back the old controversies in a new form. But this does not alter the significance of the general fact; for, in the first place, the use of an idea by any writer is by no means always limited by his own interpretation of it; and, in the second place, the true interpretation of the idea is that which contains the secret of its power and prevalence, and it must in the long run gain the victory over all other interpretations of it. We may, therefore, fairly say that these ideas have been the marked ideas of the century, the conscious or unconscious stimulus of its best thought; and that they have been working, and are working still, in the direction of a deeper and more comprehensive irenicon between the different tendencies of the human mind than has been attained in any previous stage of the history of philosophy."}]}
{"messages": [{"role": "assistant", "content": "We may, therefore, fairly say that these ideas have been the marked ideas of the century, the conscious or unconscious stimulus of its best thought; and that they have been working, and are working still, in the direction of a deeper and more comprehensive irenicon between the different tendencies of the human mind than has been attained in any previous stage of the history of philosophy. Against such a general characterization of an age, there is the same objection which Burke indicated when he said that “he could not draw up an indictment against a nation.” We are taking a distant and general view of a period, in which all its inequalities of movement, all the ebb and flow of opinion, are lost sight of, and only one main current of thought is visible. We may get a step nearer to the subject by distinguishing three periods in the century, in which there is a partial difference of tendency. The first period, which we may roughly define as lasting well on into the 30’s, is, in the main, a period of construction, of creative thought, in which the great germinating ideas that distinguished the century are more or less adequately expressed in different countries, and in which they receive a first, somewhat hasty, application to all departments of human knowledge. Idealistic philosophy, which gave the fullest expression to those ideas, seems for a time to carry all before it in Germany; and a similar movement of thought, less definitely reflective or speculative, enriches the literature of other countries. In the next period, lasting until the 70’s, the new ideas do not lose their hold upon men’s minds, but there is a certain critical recoil against them, a tendency to explain them away."}]}
{"messages": [{"role": "assistant", "content": "In the next period, lasting until the 70’s, the new ideas do not lose their hold upon men’s minds, but there is a certain critical recoil against them, a tendency to explain them away. The first premature synthesis of idealistic philosophy is attacked by a scepticism, which seems at times as if it would measure back the whole way to the individualistic materialism of an earlier age, or which only avoids that extreme to fall into a scientific agnosticism, at first sight even more hostile to the claims of philosophy. But the lesson of Kant could never be altogether forgotten, nor could the negative or sceptical tendencies of the _Critique of Pure Reason_ be permanently separated from the positive results of his later writings. And the great scientific movement of the time, which at first seemed to draw away all interest from speculative inquiry, tended in the long run, especially by the advance of biological study, to raise metaphysical questions which the methods of science were incapable of answering. Hence, in the latest decades of the century, there has come a revival of interest in philosophy, and especially in the idealistic philosophy of its first years. But if philosophy has revived, it is in a more critical and cautious form, and accompanied by a clear consciousness that the only true idealism is that which is able to absorb and assimilate all the data supplied by empirical investigation, and do justice to all the results of the special sciences."}]}
{"messages": [{"role": "assistant", "content": "But if philosophy has revived, it is in a more critical and cautious form, and accompanied by a clear consciousness that the only true idealism is that which is able to absorb and assimilate all the data supplied by empirical investigation, and do justice to all the results of the special sciences. The general movement of thought in the nineteenth century has thus, on the whole, taken an idealistic direction; but there has come with it also a deeper consciousness of the immense difficulty of a comprehensive synthesis; of the inefficacy of any easy monism or optimism, that would pluck the fruit of knowledge before it is ripe; of the infinite labor and patience, the sympathetic appreciation of the opposing views of others, and constant and unsparing criticism of our own, which are needed for the construction of a true philosophy. II \nIn a short article like this, it is impossible to give more than a few indications of the way in which this three-fold _schema_ of the history of nineteenth-century philosophy should be filled up. To give any definite impression, the writer must, so to speak, put on the seven-leagued boots of Jack the Giant Killer; in other words, however conscious he may be of the truth that _dolus latet in generalibus_, he must generalize and be content to mention only a few leading names in illustration of the tendencies of thought of which he speaks. It is the instinct of each new generation to vindicate its freedom by rebelling against the authority of its predecessors; and when a new idea begins to influence human thought, it usually, on its first appearance, shows that side which is most antagonistic to the spirit of the past. Thus the peculiar nineteenth-century movement begins with a reassertion of the _universal_ as against the _individual_, which is so emphatic that it looks like a return to Spinozism."}]}
{"messages": [{"role": "assistant", "content": "Thus the peculiar nineteenth-century movement begins with a reassertion of the _universal_ as against the _individual_, which is so emphatic that it looks like a return to Spinozism. Schelling is the most prominent philosophical representative of this tendency. In the works which he wrote about the beginning of the century, he broke away even from the universalized individualism of Fichte, and gave emphatic prominence to the great philosophical commonplace—which had been almost forgotten by the previous age—that there is an identity which is below or above all distinction, and that the universe is one through all its multiplicity, and permanent through all its changes. His maxim—that there are none but _quantitative_ differences in things, and that all these, even the difference of mind and matter, disappear in the “indifference” of the Absolute—was like a declaration of war against the “enlightenment.” It meant that philosophy was no longer content to regard the whole as the sum of the parts, but could look upon the distinction of the parts only as a differentiation of the whole. With Schelling, indeed, this differentiation was in danger of being reduced to a mere appearance and the unity of the Absolute was on the point of vanishing in a bare or abstract identity. But his strong assertion of the unity beneath all difference, of the priority of the universal to all particulars, was perhaps necessary, ere the true conception of the organic unity of the world could be arrived at."}]}
{"messages": [{"role": "assistant", "content": "But his strong assertion of the unity beneath all difference, of the priority of the universal to all particulars, was perhaps necessary, ere the true conception of the organic unity of the world could be arrived at. And the correction soon came with Hegel, who maintained that the absolute is “not substance, but subject.” For this meant that the absolute is a self-differentiating principle, realizing itself in a world of difference which is no mere appearance, but its own essential manifestation; and again—what is the counterpart or complementary truth to this—that in the world there are “degrees of reality,” and that “mind is higher in degree than nature.” But these ideas could hardly have been understood until the uncompromising assertion of the absolute unity had been made, and until the subjectivity of the Kantian and Fichtean points of view had once for all been set aside. The philosophy of Hegel derives its power from the way in which it strikes what, as I have already said, was the key-note of the nineteenth-century philosophy. In the first place, it is a philosophy of reconciliation, which attempts, through a criticism of the oppositions of philosophical theory, to reach a point of view in which they are all seen to be subordinated to the unity of one principle. His attack upon the “law of contradiction,” as formulated by scholastic logicians, meant simply that absolute distinctions are unmeaning, and that the only real differences are differences within a unity. On this principle he tried to show that all the oppositions of thought and things which have found expression in philosophy are relative oppositions, which find a solution or reconciliation in the life and movement of the whole."}]}
{"messages": [{"role": "assistant", "content": "On this principle he tried to show that all the oppositions of thought and things which have found expression in philosophy are relative oppositions, which find a solution or reconciliation in the life and movement of the whole. Hence he maintained that in all the great controversies that have divided the world, in metaphysics and psychology, in ethics and theology, the combatants have really been co-operators. Both sides, to use the expression of Leibnitz, have been “right in what they affirmed and wrong only in what they denied.” And their conflict has been the means of the evolution of a fuller truth than that which was contained in the doctrine of either party. In the second place, Hegel is guided throughout by the conception of the universe—and, in a sense, of every even relatively independent existence in it—as an organism, every element in which implies the whole, every change in which is a phase of its self-evolution. For his logical doctrine of the “_notion_” (as _Begriff_ is commonly translated) means simply that we do not see anything truly until we comprehend it as a whole, in which one principle manifests itself through all the difference of the parts and—just through their distinctions and their relations—binds itself into one individual—reality. In this sense, everything just so far as it has an independent individual existence at all is an organism."}]}
{"messages": [{"role": "assistant", "content": "In this sense, everything just so far as it has an independent individual existence at all is an organism. Lastly, while thus conceiving the universe as organic, Hegel maintained that it is not a natural but a spiritual organism. For the limited scope of a natural organism and its process cannot be regarded as commensurate with a universe, which comprehends all existence, whether classed as organic or inorganic. Only the conscious and self-conscious unity of mind can overreach and overcome such extreme antagonisms, and reduce them all to elements in the realization of its own life. We must, therefore, think of the universe as an organism which includes nature, but manifests its ultimate principle only in the life of man. We may add that in all this Hegel attempted to show that he was only working out in the sphere of speculative thought what Christianity had already expressed for the ordinary consciousness, according to its half-pictorial methods of representation."}]}
{"messages": [{"role": "assistant", "content": "We may add that in all this Hegel attempted to show that he was only working out in the sphere of speculative thought what Christianity had already expressed for the ordinary consciousness, according to its half-pictorial methods of representation. While this is the general meaning of Hegelianism, it must be added that Hegel was more successful in formulating these ideas in their logical or metaphysical form than in applying them to the results of the special sciences of nature, which he only knew at second hand; or even to the different provinces of the spiritual life and history of man, which he had studied more thoroughly. In both cases his data were very incomplete, and the scientific interpretation of them had not then been carried far enough to prepare—as, according to Hegel himself, it should prepare—for the final interpretation of philosophy. There is another circumstance to be taken into account, a circumstance which deeply affected Hegel and all the writers of his time. In the slow process of human history the new wine is always at first poured into old bottles, and only when the old bottles burst is an effort made to find new ones that will contain it safely. Hence the development of the new spirit in philosophy seemed often to go hand-in-hand with a movement of restoration in politics and religion which was not easily distinguishable from reaction."}]}
{"messages": [{"role": "assistant", "content": "Hence the development of the new spirit in philosophy seemed often to go hand-in-hand with a movement of restoration in politics and religion which was not easily distinguishable from reaction. Just as the politicians of the time could find for the newly awakened spirit of nationality no other embodiment than the institutions of the ancient _régime_, and tried to revive the old system destroyed by the Revolution, with only a few repairs and additions, so the great philosophical writers sought generally to reanimate the old scheme of life and thought by means of the new ideas, rather than completely to recast it in accordance with them. Hence, although Hegel’s _principle_ of evolution was as hostile to reaction as to revolution, as hostile to an authoritative system that denied the rights of the individual as to mere individualism, his particular doctrines, both in politics and theology, took a strongly conservative tinge. When we look more closely we see that it is only as restoration is at the same time reformation, as it makes the old forms the expression of a new life, that Hegel could logically defend them. But the form which he gave to his ideas was perplexing; it tended in many minds to identify the principle of development, which means that the future can only spring _out_ of the past and the present, with the defence of the _status quo_ in Church and State; and, on the other hand, to confuse the forces of progress with those of revolution. Thus the mediating, reconciling power of the new doctrine was for a time obscured, and its effect in raising men’s minds above the old levels of controversy was delayed."}]}
{"messages": [{"role": "assistant", "content": "Thus the mediating, reconciling power of the new doctrine was for a time obscured, and its effect in raising men’s minds above the old levels of controversy was delayed. III \nIn other countries during the earlier decades of the century a similar movement of thought is discernible, though it was not carried out anywhere with the same philosophical thoroughness as in Germany. In France the organic idea did not find any very powerful representative till the time of Comte, and even in his expression of it there is a certain ambiguity. In his well-known law of development, indeed, he seems to reproduce the individualistic doctrine of the eighteenth century, and to deny the reality of the _universal_, both in its theological and its philosophical form. But already in the last volume of his _Positive Philosophy_, when he begins to deal with human society, he maintains that “the individual man is an abstraction, and that there is nothing real but humanity”; and in his _Positive Politics_ he treats this unity of mankind as not only real, but divine. In that work, moreover, he makes another step."}]}
{"messages": [{"role": "assistant", "content": "In that work, moreover, he makes another step. Rejecting at once the obstructions of the individualists and those of the socialists, he rises to the conception of a social organism, which gives play to the competitive energy of individuals, and yet binds them together in its own more comprehensive life. In England, before the close of the eighteenth century, the same spirit had found a representative in Burke, who rejected entirely the idea of a social contract, and maintained that the State is based on an unconscious reason of society, which is far wiser than the conscious reason of even the wisest individuals. In general, however, the spiritualistic movement of the earlier part of the century took, among the English-speaking people, rather a poetic and literary than a philosophical form. And the imperfect attempts of Coleridge to transplant German ideas into England—attempts followed up with signal energy by Frederic Denison Maurice—hardly constitute an exception to this rule. In this connection, also, as one who partly grasped the organic idea of social life and its development, but who gave it a somewhat imperfect and even contradictory expression, I may mention a later writer, Thomas Carlyle, whose imaginative genius and moral enthusiasm did much to breathe a new life into history."}]}
{"messages": [{"role": "assistant", "content": "In this connection, also, as one who partly grasped the organic idea of social life and its development, but who gave it a somewhat imperfect and even contradictory expression, I may mention a later writer, Thomas Carlyle, whose imaginative genius and moral enthusiasm did much to breathe a new life into history. Though not a philosopher in any technical sense, he was, like his friend Emerson, a vehicle of philosophical ideas, and he contributed greatly to scatter the seed of idealism upon British soil. His Calvinistic pessimism, indeed, makes a curious contrast with the fearless optimism of the new country which is characteristic of Emerson; but whether great men are to be regarded as “heroes to be worshipped,” according to the teaching of the one, or as “representative men,” who are to be followed because they express what all are thinking, according to the ideas of the other, we are led, in both cases, to a deeper view of the solidarity of human society and of its spiritual basis. IV \nIt is difficult to determine more than approximately the beginning of special movements of thought; for the different nations of the civilized world are not exactly contemporaneous in their development, and in each nation there are always individuals who lag behind the time or hasten on before it. But, speaking generally, we may say that as early as the fourth decade of the century a certain reaction had set in against the conclusions of idealistic philosophy, and especially against the organic idea of human life; and a tendency was even shown to revert, so far as possible, to the methods and ideas of the eighteenth century. The reasons for this change are various."}]}
{"messages": [{"role": "assistant", "content": "The reasons for this change are various. In Germany the succession of great philosophers had come to an end, and their followers were smaller men, who were inclined too much to repeat the formulas, but had little of the creative power, of their predecessors. More attention, therefore, began to be paid to the protests of writers like Herbart and Schopenhauer, who, even in the hour of its triumph, had criticised and attacked the prevailing philosophy. Again, the physical sciences were advancing by “leaps and bounds,” and there was a growing inclination to believe in the universal validity of the mechanical methods of explanation to which _they_ owed their success, and even in those sociological and historical studies to which the idealistic philosophy had given so great an impetus. The progress of empirical research and the increase of the materials of knowledge caused much of the work of Hegel and his followers to seem inadequate, if not entirely to set it aside. Even in Germany, where the new ideas had taken a distinctly philosophical shape, they seemed to lose their hold in the controversies that attended the breaking up of the Hegelian school; and in other countries, where they never found such a systematic expression, they were even less able to resist the attack now made upon them."}]}
{"messages": [{"role": "assistant", "content": "Even in Germany, where the new ideas had taken a distinctly philosophical shape, they seemed to lose their hold in the controversies that attended the breaking up of the Hegelian school; and in other countries, where they never found such a systematic expression, they were even less able to resist the attack now made upon them. Furthermore, as I have already indicated, writers of an idealistic tendency, in their recoil from the enlightenment, had devoted themselves so much to an appreciation of institutions derived from the past that they seemed to have no eyes for the defects of these institutions, and to confuse evolution with restoration. The general result of all these influences was, then, to discredit philosophy and exalt science, so far as might be, into its place. Either the abstract methods of the physical sciences were proclaimed as adequate for the discovery of all truth, or, if this was seen to be impossible, agnosticism was professed in regard to all subjects to which these methods could not be applied. Even the phenomena of life were supposed to be capable of explanation by the action and reaction of the parts or elements of the physical organism, and Huxley looked forward to the time when man with all his spiritual endowments should be shown to be only the “cunningest of nature’s clocks.” The new science of psychophysics, which arose in Germany and has been cultivated with so much zeal by Wundt and others in all civilized countries, seemed to carry the method of physics into the investigation of mind, and some of its students were ready to maintain that it was the only psychology that deserved the name of science. Darwin’s great work on the _Origin of Species_, in so far as it set aside the idea of special creation and referred the “purposiveness” of organic structures to a process in which the external environment, and not any inward power of self-adaptation, was the controlling factor, seemed to bring a new reinforcement to the same way of thinking."}]}
{"messages": [{"role": "assistant", "content": "Darwin’s great work on the _Origin of Species_, in so far as it set aside the idea of special creation and referred the “purposiveness” of organic structures to a process in which the external environment, and not any inward power of self-adaptation, was the controlling factor, seemed to bring a new reinforcement to the same way of thinking. And he and his followers were not slow to apply the theory of natural selection to the life of man, as well as to that of plants and animals. Finally, the historical studies, which were now cultivated with an energy to an extent hitherto unexampled, and immensely extended the knowledge of the process whereby the present has grown out of the past, were invaded by a similar spirit; and the historical method was maintained to be a solvent which could disintegrate all metaphysical conceptions of ethics or politics or even of theology. The account of the genesis of any idea was regarded as reducing its claims to the level of the elements or rudiments out of which it had sprung, and thus as enabling the scientific historian to explain, or explain away, the spiritual by the natural in all human life and experience. All things appeared again to be pointing towards a system of thought which would resolve ethics and psychology into physiology, and physiology into chemistry and physics. At the same time the victory of this tendency was always more apparent than real."}]}
{"messages": [{"role": "assistant", "content": "At the same time the victory of this tendency was always more apparent than real. In the first place, “out of the eater came forth meat”—that very advance of the special sciences, which in its earlier stages had tended to throw all speculative thought into the shade, in the long run caused the need of philosophy to be again felt. In particular, the study of development in the organic world, which had received so great a stimulus from the work of Darwin, could not be carried on without the aid of higher conceptions than were required for the guidance of the physicist. The hypothesis of natural selection might expel the idea of design in the cruder form of a special creation of every distinct species; and the emphasis which it had laid upon the outward conditions of growth might seem unfavorable to the higher conception of an immanent teleology of the organism, but it was confessed by its author to be an incomplete theory of development, and Darwin himself, when he turned his attention to the evolution of man, found it necessary to supplement it by what might be called the converse theory of sexual selection; thus adding a principle of co-operation to his first principle of competition. And Mr. Spencer, who defined growth as a process of integration and differentiation, little as he might himself intend it, was really putting into popular language the Hegelian idea of evolution—an idea which necessarily involved the conception of a self-determined end."}]}
{"messages": [{"role": "assistant", "content": "Spencer, who defined growth as a process of integration and differentiation, little as he might himself intend it, was really putting into popular language the Hegelian idea of evolution—an idea which necessarily involved the conception of a self-determined end. Evolutionists might cling, as they still cling, to the belief that, though constantly and necessarily speaking of purpose, they could eliminate it from the result of their investigations by the hypothesis of Darwin, or, subsequently, of Weissmann; but their discussions, especially when they were extended to the historical development of man, could not but reawaken the great controversy whether in the _ultimate_ explanation of things it is more reasonable to “level up,” or to “level down,” to explain the higher by the lower, or the lower by the higher. That both explanations are necessary, nay, that no teleology can be of much worth which does not presuppose a thorough inquiry into the causal connections of particular phenomena, was admitted by all modern idealists. But they began to press the question whether the unity of the whole is not prior to its distribution into parts, and does not govern their relations with each other; and, in particular, whether it is possible in the case of organic beings, and especially of organic beings possessed of consciousness and self-consciousness, to be satisfied with a mode of explanation that treats them as mere collections of material elements which act and react externally upon each other. Whatever its value as a provisional hypothesis, can such a mode of explanation be finally regarded as adequate for the explanation of the nature of the world as a whole, or, indeed, of any one existence in it, that has even a relative independence or separate being of its own? But, in the second place, a revival of the idealistic philosophy was made necessary by an obvious weakness which clung to the scientific materialism of the nineteenth century from the very beginning."}]}
{"messages": [{"role": "assistant", "content": "But, in the second place, a revival of the idealistic philosophy was made necessary by an obvious weakness which clung to the scientific materialism of the nineteenth century from the very beginning. The Kantian criticism of knowledge, which could not be entirely neglected, had convincingly proved that in our experience objects can be known only in relation to a subject, and matter only in relation to mind. But, if so, how could the latter be explained by the former? Even to those who had not fully understood this doctrine, it became evident that mind is at least co-ordinate with matter, and cannot be treated as a mere “_epiphenomenon_” of it. Mr. Spencer, therefore, had to take refuge in the strange notion that we are possessed of “two consciousnesses”: the consciousness of ideas within us, and the consciousness of motions without us; and that neither of these can be resolved into the other, though both are the phenomena of an unknowable Absolute."}]}
{"messages": [{"role": "assistant", "content": "Spencer, therefore, had to take refuge in the strange notion that we are possessed of “two consciousnesses”: the consciousness of ideas within us, and the consciousness of motions without us; and that neither of these can be resolved into the other, though both are the phenomena of an unknowable Absolute. It is in this citadel of ignorance that Huxley tries to intrench himself; but the place was taken before it could be occupied. The self-contradiction of an unknowable Absolute, and the equal though less obvious self-contradiction of a dualistic separation between two aspects of our life—which, as a matter of fact, are never, and logically can never be, divided—could not long be maintained against a criticism armed with the weapons of Kant and his idealistic successors. Already, in the 50’s, the cry “Back to Kant” was raised in Germany, and, not long after, it led in England and America to a renewed study of the German idealistic writers, in which Dr. Hutchison Sterling and the late Professor Green took a leading part. It was soon obvious to every one who had learned the lesson of critical philosophy that the agnostic dualism of Mr."}]}
{"messages": [{"role": "assistant", "content": "It was soon obvious to every one who had learned the lesson of critical philosophy that the agnostic dualism of Mr. Spencer was due to a fundamental misconception of what is meant by the subjectivity of knowledge. It was pointed out that if we have the consciousness of object and subject only in relation to each other, it is not necessary to seek for the principle of their unity in any _Tertium Quid_ which is neither the one nor the other. That which Mr. Spencer sought in an unknowable Absolute was “in our mouths and in our hearts”; it was to be found in the inseparable unity of experience, in which the inward and the outward are correlative elements. Agnosticism was a sort of spiritual refuge for the destitute constructed by those who had renounced their heritage: who, in other words, had by their abstractions separated the elements of experience from each other, and were thus forced to seek beyond experience for the unity which they had lost."}]}
{"messages": [{"role": "assistant", "content": "Agnosticism was a sort of spiritual refuge for the destitute constructed by those who had renounced their heritage: who, in other words, had by their abstractions separated the elements of experience from each other, and were thus forced to seek beyond experience for the unity which they had lost. The true remedy for the evil was to give up such abstract ways of thinking and to learn to “think things together”; in other words, to recognize the organic relation of the inner and the outer life, and to explain the parts by the whole, and not the whole by the artificially severed parts. V \nThe great distinguishing feature of the last two decades of the century has been a movement of approximation, partly conscious and partly unconscious, between the representatives of science, and particularly of those sciences that deal with special aspects or elements of human life, on the one hand, and the representatives of idealistic philosophy on the other. The reconciling ideas of an earlier time have become better understood and have shown more effectively their power to reconcile. Not that this mediating power had previously been entirely unfelt. Even in the time when philosophy was most discredited in Germany, Lotze, in whom a cautious critical temper was combined with deep moral and religious sympathies, and a practical knowledge of the biological and medical sciences with careful studies of Kant and Hegel, sought to show how an idealistic view of the universe and of human life could be maintained consistently with the fullest recognition of scientific methods and results."}]}
{"messages": [{"role": "assistant", "content": "Even in the time when philosophy was most discredited in Germany, Lotze, in whom a cautious critical temper was combined with deep moral and religious sympathies, and a practical knowledge of the biological and medical sciences with careful studies of Kant and Hegel, sought to show how an idealistic view of the universe and of human life could be maintained consistently with the fullest recognition of scientific methods and results. And though his system was, on the whole, rather a compromise than a true reconciliation of philosophy and science, yet it has undoubtedly had very great influence in modifying the ideas of the opposing schools of thought and narrowing the ground of controversy between them. Thus the old English empirical psychology, which was represented by the Mills and by Mr. Bain, has gradually widened its scope in the hands of writers like Professor Ward and Mr. Stout, at first probably through the study of Herbart and then by contact with the revived idealistic movement. On the other hand, we may notice how idealistic writers, like Mr."}]}
{"messages": [{"role": "assistant", "content": "On the other hand, we may notice how idealistic writers, like Mr. Bradley and Mr. Bosanquet, have tried to absorb every lesson that can be learned from empiricism, and to shun with the utmost care the very suspicion of anything like dogmatism. Mr. Bradley’s denunciations of a “too easy monism” and a philosophy that turns the living world into a “ballet of bloodless categories” are too well known to be more than referred to. Nor is this the place to discuss whether his fear of such a result has not sometimes led him into compromises which are inconsistent with his own fundamental principle that the world must be conceived as an intelligible system."}]}
{"messages": [{"role": "assistant", "content": "Nor is this the place to discuss whether his fear of such a result has not sometimes led him into compromises which are inconsistent with his own fundamental principle that the world must be conceived as an intelligible system. In any case, we may fairly point to his work and to the work of other writers animated by a similar spirit, as showing the growing prevalence of that reconciling spirit which seeks at once to do justice to all the results of empirical inquiry and of the investigations of the special sciences, and yet at the same time to give them a new interpretation in the light of an idealistic philosophy. It is impossible within our limits to illustrate this view of the tendencies of the time by further reference to the recent philosophical literature of England and America, or of Germany and France. Still less can I refer to the numerous books on special departments of inquiry in ethics and theology, in sociology and in history, in which the “ideally organic view of life and the world,” as we may call it, has shown its mediating and reconciling influence. Nor can I do more than refer to the counter current of pessimism, which has found its most distinguished representatives in Hartmann and Nietzsche; the former a man of great wealth of thought and dialectical power, whose philosophy is idealistic in all but its ultimate principle, and is indeed pessimistic only by an exaggeration of the opposition between the conscious and the unconscious working of reason; the latter, hardly a philosopher at all but rather a writer of pungent and suggestive aphorisms, winged with indignant passion against prevalent opinions—aphorisms which always contradict some one, and often contradict each other. From Nietzsche at his best we may receive a useful warning against too easily satisfying ourselves with the commonplaces of idealistic optimism; from Hartmann we may derive very considerable help in estimating the difficulties that have to be met by those who would seek to work out idealistic principles into a systematic view of the world."}]}
{"messages": [{"role": "assistant", "content": "From Nietzsche at his best we may receive a useful warning against too easily satisfying ourselves with the commonplaces of idealistic optimism; from Hartmann we may derive very considerable help in estimating the difficulties that have to be met by those who would seek to work out idealistic principles into a systematic view of the world. But, without attempting to enter upon any more detailed criticism of these or other important writers of recent years, I shall devote the space that remains to one general thought as to the present state of controversy, in relation to the fundamental principles of philosophy. VI \nEver since the revival of the study of Kant, the main conflict in philosophy has ceased to lie between materialism and idealism. It has rather become a conflict between those who take up some position analogous to that of Kant and those who seek to carry out the idealistic principle to all its consequences. For the essential characteristic of Kant’s position lay in his sharp division between the spheres of knowledge and of faith—between a knowledge which was confined to phenomena and their connection in experience, and a faith of practical reason, which reached beyond experience to apprehend that which is noumenally real. Even the agnosticism of Mr."}]}
{"messages": [{"role": "assistant", "content": "Even the agnosticism of Mr. Spencer might be regarded as a modification of the Kantian point of view, in so far as his denial of the possibility of knowing the absolute is based on Mansel’s version of the Kantian antinomies; while his description of the “vague consciousness” of the absolute which he bids us worship may be regarded as representing that faith which, in Kant’s view, enables us to pierce the veil of the phenomena and grasp the ultimate reality of things. And in the latter part of the century there has been a continual germination of similar theories, theories agreeing with the Kantian philosophy at least in making some kind of dualistic division between the sphere of clearly defined knowledge and the sphere of ideal or spiritual faith, and also in confining the former to phenomena while the latter is held to be capable of rising in some way from the phenomenal to the real. One of the earliest fruits of the Neo-Kantian movement in Germany was Lange’s _History of Materialism_, which insisted on the strictest interpretation of the lesson of the _Critique of Pure Reason_, that scientific knowledge is confined to the empirical and phenomenal, but which maintained also the chartered freedom of imagination to feed our hopes with the idea of a world not realized, or realizable, under the conditions of finite experience. And, with a different aim, but in a similar spirit, Ritschl, borrowing some of his weapons from Lotze, sought to take away from philosophy the right to investigate the spiritual truths of religion, and maintained that such truths were given in a kind of intuition of faith which is above criticism and which some of his followers identify, like Kant, with the demands or postulates of the moral consciousness. Other writers, following Schopenhauer, have sought to emancipate the will from the intelligence and to give it an independent power of estimating values."}]}
{"messages": [{"role": "assistant", "content": "Other writers, following Schopenhauer, have sought to emancipate the will from the intelligence and to give it an independent power of estimating values. The great effort to bring science and philosophy together—which, as we have seen, has characterized the later years of the century—has itself naturally given rise to many such dualistic compromises, of which Lotze’s philosophy was among the earliest. And it is partly to Lotze’s influence that we owe the tendency, visible in some of the most important recent contributions to philosophy, to regard our actual experience as having an intuitive completeness which is beyond all analysis, while reflective thought on the other hand is conceived as having a purely analytic and discursive operation, which can grasp only the severed fragments of the given reality and connect them externally to each other, but which can never restore the organic whole again. Here, too, we seem by another way to be landed in the same conclusion, viz., that we are perpetually poised between an ideal which we cannot verify, but which yet is held to be our only vision of reality, and a definite result of knowledge, which only gives us what is abstract and phenomenal. Yet it is difficult to understand how such an organic idea of the universe can exist except for the thinking intelligence, and how the thought that grasps it can be separated from the discursive thought by which the different elements of reality are brought into relation. How, indeed, can there be any thought which is not both discursive and intuitive at once, any thought which connects the parts without resting upon the unity of the whole to which they belong?"}]}
{"messages": [{"role": "assistant", "content": "How, indeed, can there be any thought which is not both discursive and intuitive at once, any thought which connects the parts without resting upon the unity of the whole to which they belong? All these different compromises are really different forms of the Kantian dualism, but they supply convenient cities of refuge for those who are unwilling to admit that faith is but implicit reason, and that it is always possible to translate its intuitions of truth into explicit logic. There is much excuse, indeed, in many cases for such unwillingness when we consider how often reason has presented itself as purely a critical or dissolving power, and how often abstract theories which grasp only one aspect of things have been set forth as complete explanations of religion or morality or some other of the higher interests of life. It has always to be kept in view that it is in something like immediate perception that truth is given in the first instance, and that philosophy, therefore, must always be in a sense toiling after the intuitions of faith. Yet, on the other hand, to hold that there is anywhere an abstract division between the two is to hold that faith is essentially irrational; it is to exalt it above reason in a way that inevitably leads in the end to its being depressed below reason. If, however, this view can be maintained it must lead in the long run to the rejection of all dualistic compromises."}]}
{"messages": [{"role": "assistant", "content": "If, however, this view can be maintained it must lead in the long run to the rejection of all dualistic compromises. And there are already many who hold that after the unstable equilibrium of the Kantian theory has been shaken there is no secure standing-ground for philosophy short of a thorough-going idealism. Yet even they have learned by experience how dangerous it is to snatch prematurely at the readiest idealistic interpretation of facts; and they are aware how easy it is to fall into a simple optimistic theory, which slurs over difficulties instead of solving them. They know that if Hegel or any one ever pretended, or could reasonably be interpreted as pretending, to construe the universe _a priori_, the pretence was futile, and that a true and valuable idealism can be reached only through the interpretation of the data of experience by the special sciences, and the reinterpretation of the results of these sciences by philosophy. They hold, in short, that if the well-known saying of Hegel is to be taken for truth, both of its clauses must be equally emphasized, and that no philosophy can safely maintain that “what is rational is actual” which has not gone through all the effort that is necessary to prove that “what is actual is rational.” \n            EDWARD CAIRD. MEDICINE \n\nINTRODUCTION \nFor countless generations the prophets and kings of humanity have desired to see the things which men have seen, and to hear the things which men have heard in the course of the wonderful nineteenth century."}]}
{"messages": [{"role": "assistant", "content": "MEDICINE \n\nINTRODUCTION \nFor countless generations the prophets and kings of humanity have desired to see the things which men have seen, and to hear the things which men have heard in the course of the wonderful nineteenth century. To the call of the watchers on the towers of progress there had been the one sad answer—the people sit in darkness and in the shadow of death. Politically, socially, and morally the race had improved, but for the unit, for the individual, there was little hope. Cold philosophy shed a glimmer of light on his path, religion in its various guises illumined his sad heart, but neither availed to lift the curse of suffering from the sin-begotten son of Adam. In the fulness of time, long expected, long delayed, at last Science emptied upon him from the horn of Amalthea blessings which cannot be enumerated, blessings which have made the century forever memorable; and which have followed each other with a rapidity so bewildering that we know not what next to expect. To us in the medical profession, who deal with this unit, and measure progress by the law of the greatest happiness to the greatest number, to us whose work is with the sick and suffering, the great boon of this wonderful century, with which no other can be compared, is the fact that the leaves of the tree of Science have been for the healing of the nations."}]}
{"messages": [{"role": "assistant", "content": "To us in the medical profession, who deal with this unit, and measure progress by the law of the greatest happiness to the greatest number, to us whose work is with the sick and suffering, the great boon of this wonderful century, with which no other can be compared, is the fact that the leaves of the tree of Science have been for the healing of the nations. Measure as we may the progress of the world—materially, in the advantages of steam, electricity, and other mechanical appliances; sociologically, in the great improvement in the conditions of life; intellectually, in the diffusion of education; morally, in a possibly higher standard of ethics—there is no one measure which can compare with the decrease of physical suffering in man, woman, and child when stricken by disease or accident. This is the one fact of supreme personal import to every one of us. This is the Promethean gift of the century to man. THE GROWTH OF SCIENTIFIC MEDICINE \nThe century opened auspiciously, and those who were awake saw signs of the dawn. The spirit of Science was brooding on the waters."}]}
{"messages": [{"role": "assistant", "content": "The spirit of Science was brooding on the waters. In England the influence of John Hunter stimulated the younger men to the study of the problems of anatomy and pathology. On the Continent the great Boorhaave—the Batavian Hippocrates—had taught correct ways in the study of the clinical aspects of disease, and the work of Haller had given a great impetus to physiology. The researches of Morgagni had, as Virchow had remarked, introduced anatomical thinking into medicine. But theories still controlled practice. Under the teaching of Cullen, the old idea that humors were the seat of disease had given place to a neuro-pathology which recognized the paramount influence of the nervous system in disease."}]}
{"messages": [{"role": "assistant", "content": "Under the teaching of Cullen, the old idea that humors were the seat of disease had given place to a neuro-pathology which recognized the paramount influence of the nervous system in disease. His colleague at Edinburgh, Brown, brought forward the attractive theory that all diseases could be divided into two groups, the one caused by excess of excitement—the sthenic—the other by a deficiency—the asthenic—each having its appropriate treatment, the one by depletion, the other by stimulation. In a certain measure Hahnemann’s theory of homœopathy was a reaction against the prevalent theories of the day, and has survived through the century, though in a much modified form. Some of his views were as follows: \n“The only vocation of the physician is to heal; theoretical knowledge is of no use. In a case of sickness he should only know what is curable and the remedies. Of the diseases he cannot know anything except the symptoms."}]}
{"messages": [{"role": "assistant", "content": "Of the diseases he cannot know anything except the symptoms. There are internal changes, but it is impossible to learn what they are; symptoms alone are accessible; with their removal by remedies the disease is removed. Their effects can be studied in the healthy only. They act on the sick by causing a disease similar to that which is to be combated, and which dissolves itself into this similar affection. The full doses required to cause symptoms in the well are too large to be employed as remedies for the sick. The healing power of a drug grows in an inverse proportion to its substance."}]}
{"messages": [{"role": "assistant", "content": "The healing power of a drug grows in an inverse proportion to its substance. He says, literally: ‘Only potencies are homœopathic medicines.’ ‘I recognize nobody as my follower but him who gives medicine in so small doses as to preclude the perception of anything medicinal in them by means either of the senses or of chemistry.’ ‘The pellets may be held near the young infant when asleep.’ ‘Gliding the hand over the patient will cure him, provided the manipulation is done with firm intention to render as much good with it as possible, for its power is in the benevolent will of the manipulator.’ Such is the homœopathy of Hahnemann, which is no longer recognized in what they call homœopathy to-day.”—(A. JACOBI.) \nThe awakening came in France. In 1801 Bichat, a young man, published a work on general anatomy, in which he placed the seat of disease, not in the organs, but in the tissues or fabrics of which they were composed, which gave an extraordinary impetus to the investigation of pathological changes. Meanwhile, the study of the appearances of organs and bodies when diseased (morbid anatomy), which had been prosecuted with vigor by Morgagni in the eighteenth century, had been carried on actively in Great Britain and on the Continent, and the work of Broussais stimulated a more accurate investigation of local disorders. The discovery by Laennec of the art of auscultation, by which, through changes in the normal sounds within the chest, various diseases of the heart and lungs could be recognized, gave an immense impetus to clinical research."}]}
{"messages": [{"role": "assistant", "content": "The discovery by Laennec of the art of auscultation, by which, through changes in the normal sounds within the chest, various diseases of the heart and lungs could be recognized, gave an immense impetus to clinical research. The art of percussion, discovered by Avenbrugger in the eighteenth century, and reintroduced by Corvisart, contributed not a little to the same. Laennec’s contributions to the study of diseases of the lungs, of the heart, and of the abdominal organs really laid the foundation of modern clinical medicine. A little later Bright published his researches on diseases of the kidneys, from which we date our knowledge of this important subject. One of the most complicated problems of the first half of the century related to the differentiation of the fevers. The eruptive fevers, measles, scarlet fever, and small-pox, were easily recognized, and the great group of malarial fevers was well known; but there remained the large class of continued fevers, which had been a source of worry and dispute for many generations."}]}
{"messages": [{"role": "assistant", "content": "The eruptive fevers, measles, scarlet fever, and small-pox, were easily recognized, and the great group of malarial fevers was well known; but there remained the large class of continued fevers, which had been a source of worry and dispute for many generations. Louis clearly differentiated typhoid fever, and by the work of his American pupils, W. W. Gerhard and Alfred Stillé, of Philadelphia, and George B. Shattuck, of Boston, typhus and typhoid fevers were defined as separate and independent affections. Relapsing fever, yellow fever, dengue, etc., were also distinguished."}]}
{"messages": [{"role": "assistant", "content": "Relapsing fever, yellow fever, dengue, etc., were also distinguished. The work of Graves and Stokes, of Dublin, of Jenner and Budd, in England, of Drake, Dickson, and Flint, in America, supplemented the labors of the French physicians, and by the year 1860 the profession had reached a sure and safe position on the question of the clinical aspects of fevers. The most distinguishing feature of the scientific medicine of the century has been the phenomenal results which have followed _experimental investigations_. While this method of research is not new, since it was introduced by Galen, perfected by Harvey, and carried on by Hunter, it was not until well into the middle of the century that, by the growth of research laboratories, the method exercised a deep influence on progress. The lines of experimental research have sought to determine the functions of the organs in health, the conditions under which perversion of these functions occur in diseases, and the possibility of exercising protective and curative influences on the processes of disease. The researches of the physiological laboratories have enlarged in every direction our knowledge of the great functions of life—digestion, assimilation, circulation, respiration, and excretion."}]}
{"messages": [{"role": "assistant", "content": "The researches of the physiological laboratories have enlarged in every direction our knowledge of the great functions of life—digestion, assimilation, circulation, respiration, and excretion. Perhaps in no department have the results been more surprising than in the growth of our knowledge of the functions of the brain and nerves. Not only has experimental science given us clear and accurate data upon the localization of certain functions of the brain and of the paths of sensatory and of motor impulses, but it has opened an entirely new field in the diagnosis and treatment of the diseases of these organs, in certain directions of a most practical nature, enabling us to resort to measures of relief undreamed of even thirty years ago. The study of physiology and pathology within the past half-century has done more to emancipate medicine from routine and the thraldom of authority than all the work of all the physicians from the days of Hippocrates to Jenner, and we are as yet but on the threshold. THE GROWTH OF SPECIALISM \nThe restriction of the energies of trained students to narrow fields in science, while not without its faults, has been the most important single factor in the remarkable expansion of our knowledge. Against the disadvantages in a loss of breadth and harmony there is the compensatory benefit of a greater accuracy in the application of knowledge in specialism, as is well illustrated in the cultivation of special branches of practice."}]}
{"messages": [{"role": "assistant", "content": "Against the disadvantages in a loss of breadth and harmony there is the compensatory benefit of a greater accuracy in the application of knowledge in specialism, as is well illustrated in the cultivation of special branches of practice. Diseases of the skin, of the eye, of the ear, of the throat, of the teeth, diseases of women and of children, are now studied and practised by men who devote all their time to one limited field of work. While not without minor evils, this custom has yielded some of the great triumphs of the profession. Dentistry, ophthalmology, and gynæcology are branches which have been brought to a state of comparative perfection, and very largely by the labors of American physicians. In the last-named branch the blessings which have been brought to suffering women are incalculable, not only as regards the minor ailments of life, but in the graver and more critical accidents to which the sex is liable. One of the most remarkable and beneficial reforms of the century has been in the attitude of the profession and the public to the subject of insanity, and the gradual formation of a body of men in the profession who labor to find out the cause and means of relief of this most distressing of all human maladies."}]}
{"messages": [{"role": "assistant", "content": "One of the most remarkable and beneficial reforms of the century has been in the attitude of the profession and the public to the subject of insanity, and the gradual formation of a body of men in the profession who labor to find out the cause and means of relief of this most distressing of all human maladies. The reform movement inaugurated by Tuke in England, by Rush in the United States, by Pinel and Esquirol in France, and by Jacobi and Hasse in Germany, has spread to all civilized countries, and has led not only to an amelioration and improvement in the care of the insane, but to a scientific study of the subject which has already been productive of much good. In this country, while the treatment of the insane is careful and humanitarian, the unfortunate affiliation of insanity with politics is still in many States a serious hinderance to progress. It may be interesting to take a glance at the state of medicine in this country at the opening of the nineteenth century. There were only three schools of medicine, the most important of which were the University of Pennsylvania and the Harvard. There were only two general hospitals."}]}
{"messages": [{"role": "assistant", "content": "There were only two general hospitals. The medical education was chiefly in the hands of the practitioners, who took students as apprentices for a certain number of years. The well-to-do students and those wishing a better class of education went to Edinburgh or London. There were only two or three medical journals, and very few books had been published in the country, and the profession was dependent entirely upon translations from the French and upon English works. The only medical libraries were in connection with the Pennsylvania Hospital and the New York Hospital. The leading practitioners in the early years were Rush and Physick, in Philadelphia; Hossack and Mitchill, in New York; and James Jackson and John Collins Warren, in Boston."}]}
{"messages": [{"role": "assistant", "content": "The leading practitioners in the early years were Rush and Physick, in Philadelphia; Hossack and Mitchill, in New York; and James Jackson and John Collins Warren, in Boston. There were throughout the country, in smaller places, men of great capabilities and energy, such as Nathan Smith, the founder of the Medical Schools of Dartmouth and of Yale, and Daniel Drake in Cincinnati. After 1830 a remarkable change took place in the profession, owing to the leaven of French science brought back from Paris by American students. Between 1840 and 1870 there was a great increase in the number of medical schools, but the general standard of education was low—lower, indeed, than had ever before been reached in the medical profession. The private schools multiplied rapidly, diplomas were given on short two-year sessions, and nothing contributed more to the degeneration of the profession than this competition and rivalry between ill-equipped medical schools. The reformation, which started at Harvard shortly after 1870, spread over the entire country, and the rapid evolution of the medical school has been one of the most striking phenomena in the history of medicine in the century."}]}
{"messages": [{"role": "assistant", "content": "The reformation, which started at Harvard shortly after 1870, spread over the entire country, and the rapid evolution of the medical school has been one of the most striking phenomena in the history of medicine in the century. University authorities began to appreciate the fact that medicine was a great department of knowledge, to be cultivated as a science and promoted as an art. Wealthy men felt that in no better way could they contribute to the progress of the race than by the establishment of laboratories for the study of disease and hospitals for the care of the sick poor. The benefactions of Johns Hopkins, of Sims, of Vanderbilt, of Pierpont Morgan, of Strathcona, of Mount-Stephen, of Payne, and of Levi C. Lane and others have placed scientific medicine on a firm basis. THE GROWTH OF PREVENTIVE MEDICINE \nSanitary science, hygiene, or preventive medicine may claim to be one of the brightest spots in the history of the nineteenth century."}]}
{"messages": [{"role": "assistant", "content": "THE GROWTH OF PREVENTIVE MEDICINE \nSanitary science, hygiene, or preventive medicine may claim to be one of the brightest spots in the history of the nineteenth century. Public hygiene was cultivated among the Egyptians, and in the Mosaic law it reached a remarkable organization. The personal hygiene of the Greeks was embraced in the saying, “The fair mind in the fair body,” and the value of exercise and training was fully recognized. The Romans, too, in public and private hygiene, were our superiors in the matter of water supply and baths. But modern sanitary science has a much wider scope and is concerned with the causes of disease quite as much as with the conditions under which these diseases prevail. The foundations of the science were laid in the last century with Jenner’s discovery of vaccination."}]}
{"messages": [{"role": "assistant", "content": "The foundations of the science were laid in the last century with Jenner’s discovery of vaccination. Howard, too, had grasped the association of fever with overcrowding in the jails, while the possibility of the prevention of scurvy had been shown by Captain Cook and by Sir Gilbert Blaine. Preventive medicine was a blundering, incomplete science until bacteriology opened unheard-of possibilities for the prevention of disease. Before discussing some of the victories of preventive medicine it will be well to take a brief survey of the growth of the following subject: \n\nSCIENCE OF BACTERIOLOGY \nFrom the brilliant overthrow by Pasteur, in 1861, and by Koch and Cohn, in 1876, of the theory of spontaneous generation, we may date its modern growth. Wrapped up in this theory of spontaneous generation, upon which speculation raged centuries before the invention of the microscope, lies the history of bacteriology. The ancient Greek and Roman philosophers wrestled with the question, and very interesting views of the relation of germ life to disease are preserved to us in their manuscripts."}]}
{"messages": [{"role": "assistant", "content": "The ancient Greek and Roman philosophers wrestled with the question, and very interesting views of the relation of germ life to disease are preserved to us in their manuscripts. With the invention of the microscope we can mark the first positive step towards the goal of to-day. A Jesuit priest, Kircher, in 1671, was the first to investigate putrefying meat, milk, and cheese with the crude microscope of his day, and left us indefinite remarks concerning “very minute living worms” found therein. Four years after Kircher a Dutch linen merchant, Antonius von Leeuwenhoek, by improving the lenses of the microscope, saw in rain-water, putrefying fluids, intestinal contents, and saliva, minute, moving, living particles, which he called “animalculæ.” In medical circles of his day these observations aroused the keenest interest, and the theory that these “animalculæ” might be the cause of all disease was eagerly discussed. Pleincz, of Vienna, after much observation of various fluids, putrefying and otherwise, wrote in 1762 that it was his firm belief that the phenomena of diseases and the decomposition of animal fluids were wholly caused by these minute living things. Notwithstanding such assertions, from his day on until Pasteur, Koch, and Cohn finally proved its misconceptions in 1876, the theory of spontaneous generation held the upper hand in all discussions upon the question."}]}
{"messages": [{"role": "assistant", "content": "Notwithstanding such assertions, from his day on until Pasteur, Koch, and Cohn finally proved its misconceptions in 1876, the theory of spontaneous generation held the upper hand in all discussions upon the question. The stimulus to research as to the causes of disease along the line of bacterial origin did not entirely cease to be felt, and the names of Pollender and Davaine are linked together in the first undoubted discovery of micro-organisms in disease, when the cause of anthrax, a disease of cattle, was solved in 1863. Following closely upon Davaine’s researches, the primary causes of wound infection were worked out, and to the efforts of the British surgeon Lister are due the great advances of modern surgery. In rapid succession the presence of bacteria was clearly demonstrated in relapsing fever, leprosy, and typhoid fever; but far eclipsing all former discoveries, on account of the magnitude of the difficulties encountered and overcome, were the brilliant demonstrations of the cause of consumption and allied diseases, and that of Asiatic cholera, by Dr. Robert Koch in 1882 and in 1884 respectively. From that time onward innumerable workers have satisfied the critical scientific world as to the causes of pneumonia, diphtheria, tetanus, influenza, and bubonic plague, besides many diseases of cattle, horses, sheep, and other animals and insects."}]}
{"messages": [{"role": "assistant", "content": "From that time onward innumerable workers have satisfied the critical scientific world as to the causes of pneumonia, diphtheria, tetanus, influenza, and bubonic plague, besides many diseases of cattle, horses, sheep, and other animals and insects. Having glanced hastily at the history of bacteriology, we may next consider some facts concerning the germs themselves. What are they? To the lay mind the words germ, microbe, bacterium, and bacillus often convey confused ideas of invisible, wriggling, worm-like creatures, enemies of mankind, ever on the watch to gain a stealthy entrance into our bodies, where they wreak harm and death. Scientifically considered, however, they are the smallest of living things yet known. They are not animals, but are members of the vegetable kingdom, and are possessed of definite yet varying shapes."}]}
{"messages": [{"role": "assistant", "content": "They are not animals, but are members of the vegetable kingdom, and are possessed of definite yet varying shapes. They consist of a jelly-like substance called protoplasm, which is covered in and held in place by a well-formed membrane of a relatively hard and dense character, exactly similar in composition to the woody fibre of trees. According to their shape the bacteria are divided into three chief groups, called respectively cocci, bacilli, and spirilla. The cocci are spherical bodies and may exist singly or in pairs, in fours, in clusters, or in chains. In this group we find the smallest bacteria known, many of them not over 1-150,000 of an inch in diameter. The bacilli are rod-like bodies, varying much in size in different species and in members of the same species."}]}
{"messages": [{"role": "assistant", "content": "The bacilli are rod-like bodies, varying much in size in different species and in members of the same species. They are larger than the cocci, measuring in length from 1-25,000 of an inch to 1-4000, and in breadth from 1-125,000 to 1-16,000 of an inch. Many varieties are possessed of organs of locomotion called flagella. The spirilla resemble the bacilli, except that they are twisted into corkscrew shapes, or have gently undulating outlines. Upon an average they are much longer than the bacilli, one species being very long, measuring about 1-600 of an inch. As seen in the natural state bacteria are found to be colorless, but it is by the application of various aniline dyes that they are usually studied."}]}
{"messages": [{"role": "assistant", "content": "As seen in the natural state bacteria are found to be colorless, but it is by the application of various aniline dyes that they are usually studied. These minute plants increase by a simple method of division into two equal parts, or by a more complex process of forming a seed—the so-called spore—which later on develops into the adult form. Under favorable conditions they are able to multiply at an enormous rate; for instance, it has been calculated that a bacillus dividing once every hour would at the end of twenty-four hours have increased to seventeen millions; and if the division continued at the same rate we should find at the end of the third day an incalculable number of billions, whose weight would be nearly seven thousand five hundred tons! But, fortunately for our welfare, nature by various means renders the possibility of such a happening entirely beyond the slightest chance of realization, her greatest barrier being the lack of an adequate food supply. The distribution in nature of bacteria is wellnigh universal, occurring as they do in the air we breathe, the water and milk we drink, upon the exposed surfaces of man and animals, and in their intestinal tracts, and in the soil to a depth of about nine feet. But it has been noted that at very high altitudes and in glacier ice none exist, while in the Arctic regions and at sea far from land their numbers are very few."}]}
{"messages": [{"role": "assistant", "content": "But it has been noted that at very high altitudes and in glacier ice none exist, while in the Arctic regions and at sea far from land their numbers are very few. The conditions governing their growth involve many complex problems, but a few of the chief factors concerned are moisture, air, food, temperature, and light. All bacteria must have moisture, else they die sooner or later, depending upon the hardness of the species, and none can multiply without it. A supply of air is by no means essential to all germs. To some it is absolutely necessary, and such germs are called aerobes. To others air is wholly detrimental, and they constitute the anaerobes, while to the majority of bacteria air supply is a matter of indifference, and in consequence they are grouped under the term facultative anaerobes."}]}
{"messages": [{"role": "assistant", "content": "To others air is wholly detrimental, and they constitute the anaerobes, while to the majority of bacteria air supply is a matter of indifference, and in consequence they are grouped under the term facultative anaerobes. The food supply of many consists of dead animal and vegetable materials, a few require living tissues, while a small number can exist wholly upon mineral salts, or even the nitrogen of the air. The lowest temperature at which some bacteria can multiply is the freezing-point of water, and the highest 170 degrees Fahrenheit. However, the average range of temperature suitable to the majority lies between 60 and 104 degrees Fahrenheit, 98 2-5 degrees Fahrenheit being the most suitable for the growth of disease-producing germs. Light, ordinarily diffused daylight, or its absence, is a matter of no moment to most germs, whereas direct sunlight is a destroyer of all bacteria. The study of the life histories of these diminutive plants excites the wonder of those who make observations upon them."}]}
{"messages": [{"role": "assistant", "content": "The study of the life histories of these diminutive plants excites the wonder of those who make observations upon them. It is truly marvellous to know that these bacteria can accomplish in their short lives of possibly a few hours or days feats which would baffle the cleverest of chemists if given years of a lifetime to work upon. They give to the farmer the good quality of his crops, to the dairyman superior butter and cheese; they assist in large measure in freeing our rivers and lakes from harmful pollutions. Here it should be strongly emphasized that those bacteria which cause disease are only of a few species, all others contributing to our welfare in countless ways. Quite as astonishing is the discovery that within the root-knobs of pease and beans live bacteria which by splitting up mineral salts containing nitrogen, and by absorbing nitrogen from the air, give it over to the plant so that it is enabled to grow luxuriantly, whereas, without their presence, the tiller of the soil might fertilize the ground in vain. It is quite possible that not alone pease and beans, but all grasses and plants and trees depend upon the presence of such germs for their very existence, which in turn supply man and animals with their means of existence."}]}
{"messages": [{"role": "assistant", "content": "It is quite possible that not alone pease and beans, but all grasses and plants and trees depend upon the presence of such germs for their very existence, which in turn supply man and animals with their means of existence. Hence we see that these nitrifying bacteria, as they are called, if swept out of existence, would be the cause of cessation of all life upon the globe. And arguing backward, one prominent authority states it as his belief that the first of all life on this earth were those lowly forms of plants which only required the nitrogen of air or salts to enable them to multiply. Limiting observation now to the sphere of medicine, it will be readily perceived that the presence of bacterial life in a causative relation to disease is an object of paramount regard. The following paragraphs will briefly treat of the diseases associated with micro-organisms and the common modes of infection in each, the chain of events subsequent to an infection, and the possibilities of protection or cure by means of substances elaborated in the body of an individual or animal recently recovered from an infectious disease: \n_Anthrax._—A disease chiefly of cattle and sheep, occasionally of man, is caused by the _Bacillus anthracis_, discovered in 1849–50 by Pollender and Davaine. It enters the body through abrasions of the skin, by inhalation of the spores, or seeds, into the lungs, or by swallowing infected material."}]}
{"messages": [{"role": "assistant", "content": "It enters the body through abrasions of the skin, by inhalation of the spores, or seeds, into the lungs, or by swallowing infected material. _Leprosy._—This disease is caused by a bacillus known as _Bacillus leprae_, which was discovered by Hansen in 1879. It is doubtful if it has been grown outside the body. It is supposed to enter by abrasions of the skin, but it is very feebly contagious, notwithstanding popular ideas as to its supposedly highly contagious nature. _Tuberculosis._—All forms of this disease, among which is ordinary consumption, are caused by a bacillus closely resembling that of leprosy. It was discovered by Koch in 1880–82, and named _Bacillus tuberculosis_."}]}
{"messages": [{"role": "assistant", "content": "It was discovered by Koch in 1880–82, and named _Bacillus tuberculosis_. The ways of infection are by inhaling the dried sputum of consumptives, drinking infected cow’s milk, or eating infected meat. _Typhoid Fever._—A disease of human beings only. Eberth in 1880 discovered the germ causing it and called it _Bacillus typhosus_. It gains entrance to our bodies chiefly in the milk and water we drink, which comes from infected sources; a rarer method is by inhalation of infected air. _Diphtheria._—A disease of human beings chiefly."}]}
{"messages": [{"role": "assistant", "content": "_Diphtheria._—A disease of human beings chiefly. It is caused by a bacillus which was described in 1883–84 by Klebs and Loeffler, and is known as _Bacillus diphtheriae_, or Klebs-Loeffler bacillus. Its mode of entry is by inhaling infected air, or by drinking or eating infected milk or food. _Cholera._—This disease is peculiar to human beings. Its native home is on the banks of the river Ganges in India, where Koch in 1884 was able to isolate its causative spirillum. Man is infected by drinking contaminated water or by contact."}]}
{"messages": [{"role": "assistant", "content": "Man is infected by drinking contaminated water or by contact. _Lockjaw, or Tetanus._—Afflicts man, horses, and dogs. The _Bacillus tetani_ is the most deadly of all known bacteria. It enters the body by wounds. It was discovered in 1884 by Nicolaier. _Influenza, or the Grip._—Caused by one of the smallest-known bacilli; discovered in 1892 by Canon and Pfeiffer."}]}
{"messages": [{"role": "assistant", "content": "_Influenza, or the Grip._—Caused by one of the smallest-known bacilli; discovered in 1892 by Canon and Pfeiffer. Infection spreads by the scattering about by air-currents of the dried nasal and bronchial secretion of those suffering from the disease, and its portal of entry is by the nose and bronchial tubes. _Pneumonia._—Caused by a coccus which grows in pairs and small chains. It enters the body by means of the respiratory tract. It is present in the saliva of twenty per cent. of healthy persons."}]}
{"messages": [{"role": "assistant", "content": "of healthy persons. Proved by Frankel in 1886 to be the cause of this disease. _Bubonic Plague._—In 1894 Kitasato and Yersin isolated a small bacillus in a large number of cases and proved it to be the cause. It enters the body by means of wounds of the skin, and through bites of fleas from infected rats, which are said to be one of the chief factors in spreading this dread malady. _Yellow Fever._—The cause of this disease is still under discussion. Such are a few of the infectious diseases which we can readily attribute to the presence of definite micro-organisms in respective cases."}]}
{"messages": [{"role": "assistant", "content": "Such are a few of the infectious diseases which we can readily attribute to the presence of definite micro-organisms in respective cases. But strange as it may seem, the most typical of all infectious diseases, small-pox, scarlet fever, measles, and hydrophobia, have as yet not yielded up their secrets. This is possibly due to the minute size of the micro-organisms concerned, which make it beyond the power of the best microscope to demonstrate them. In this connection it has recently been shown by Roux and Nocard that in the case of the disease known as pleuro-pneumonia of cattle the causative agent is so very small as just to be barely visible. Again, it is quite possible that these diseases may be caused by living things we know nothing about, which may be quite dissimilar from the bacteria. INFECTION—ITS PROCESSES AND RESULTS \nIn the foregoing list of diseases associated with specific bacteria, attention has been drawn to the common modes of infection, or, as they are technically called, “portals of entry,” and it now remains to touch upon the main factors, processes, and results following upon the entry into the body of such disease-producing microbes."}]}
{"messages": [{"role": "assistant", "content": "INFECTION—ITS PROCESSES AND RESULTS \nIn the foregoing list of diseases associated with specific bacteria, attention has been drawn to the common modes of infection, or, as they are technically called, “portals of entry,” and it now remains to touch upon the main factors, processes, and results following upon the entry into the body of such disease-producing microbes. It is a well-known fact that the normal blood has of itself to a considerable extent the power of killing germs which may wander into it through various channels. Likewise the tissue cells of the body in general show similar action depending upon the different cell groups, state of health, general robustness, and period of life. The germ-killing power varies in different individuals, though each may be quite healthy. Considered as a whole, this power possessed by the body against germs is known as “general resistance.” And when by any means this power of resistance is lost or diminished, we run grave risks of incurring disease. Granted a case of infection, let us now trace up briefly what occurs."}]}
{"messages": [{"role": "assistant", "content": "Granted a case of infection, let us now trace up briefly what occurs. Between the period when the bacteria gain a lodgment and that in which the disease assumes a noticeable form, the patient simply feels out of sorts. It is during this stage that the blood and tissues are deeply engaged in the attempt to repel the attacks of the invading microbes. With varying speed the germs multiply throughout the body generally, or may be at first localized, or even, as in lockjaw, remain localized throughout the entire disease. Multiplying in the tissues, they generate in increasing amounts their noxious poisons, which soon cause profound changes throughout the body; the patient becomes decidedly ill, and shows now the signs of an unmistakable infection. Does the body now give up the fight entirely?"}]}
{"messages": [{"role": "assistant", "content": "Does the body now give up the fight entirely? No; on the contrary, the white blood-cells, the wandering cells, and the cells of the tissues most affected still carry on an unequal fight. From the lymphatic glands and spleen, armies of white cells rush to the fray and attempt to eat up and destroy the foe, but possibly in vain; the disease runs its course, to end either in death or recovery. How, then, in cases of recovery, are the microbes finally overcome? This question involves many complex processes which at present are by no means thoroughly understood, but we will concern ourselves with the simple principles. It has been previously mentioned that once the bacteria get a good foothold the body is subjected to the action of generated poisons, which are known as toxins."}]}
{"messages": [{"role": "assistant", "content": "It has been previously mentioned that once the bacteria get a good foothold the body is subjected to the action of generated poisons, which are known as toxins. They give rise to such symptoms as loss of appetite, headache, fever, pains and aches, and even a state of stupor or unconsciousness. In addition to the active warfare of the white blood-cells, groups of cells throughout the body, after recovering from the first rude shock of the toxins, begin to tolerate their presence, then effect a change in the chemical constitution of the toxins, and finally elaborate substances which antagonize the toxins and destroy their action altogether, thus lending aid to the warrior cells, which at last overcome the invading microbes. Recovery is brought about, and a more or less permanent degree of immunity against the special form of disease ensues. Now if we could use these antagonizing substances, or, as they are called, antitoxins, upon other men or animals sick with a similar disease, would their bodies be at once strengthened to resist and finally overcome the disease? Yes, in a certain majority of cases they would, and this is exactly what scientific observers have noted, worked out, and have successfully applied."}]}
{"messages": [{"role": "assistant", "content": "Yes, in a certain majority of cases they would, and this is exactly what scientific observers have noted, worked out, and have successfully applied. A new art in the healing of disease, which is spoken of broadly as serum-therapy, or medication by curative or protective serums, has thus been discovered. The first observers in this new field were Pasteur and Raynaud in France in 1877–78, and Salmon and Smith in this country in 1886. Raynaud, by injecting serum from a calf which had had an attack of cow-pox, prevented the appearance of the disease in a calf freshly inoculated with the virulent material of the disease. Pasteur, by using feebly infective germs of fowl cholera, conferred immunity upon healthy fowls against the disease, and was able to cure those which were ill. Salmon and Smith injected small and repeated amounts of the elaborated toxins or poisons of the bacillus of hog cholera into healthy swine, and were able to confer immunity upon them."}]}
{"messages": [{"role": "assistant", "content": "Salmon and Smith injected small and repeated amounts of the elaborated toxins or poisons of the bacillus of hog cholera into healthy swine, and were able to confer immunity upon them. However, it was not until Behring in 1892 announced his discovery of an antitoxin serum for diphtheria, along with an undisputed proof of its value in treatment, that the attention of the scientific world was finally aroused and stimulated to the appreciation of the great possibilities of serum-therapy. Strange as it may seem, much opposition arose to this new method of treatment, not alone from the lay portions of the community, but even from the ranks of the medical profession itself. This opposition was due in part to misconceptions of the principles involved in the new doctrine, and in part to the falsely philanthropic prejudices of the pseudo-scientific sections of both parties. But by the persevering work of the enthusiastic believers in serum-therapy, positive conviction has now replaced misconception and prejudice in the minds of the majority of its former opponents. The accumulation of statistical evidence, even where all allowance is made for doubtful methods of compilation, shows that the aggregate mortality of diphtheria has been reduced fully fifty per cent."}]}
{"messages": [{"role": "assistant", "content": "The accumulation of statistical evidence, even where all allowance is made for doubtful methods of compilation, shows that the aggregate mortality of diphtheria has been reduced fully fifty per cent. since the introduction of antitoxic treatment by Behring in 1892. Since the method of preparation of the commercial diphtheria antitoxin illustrates the general principles involved in the search for the production of curative or protective serums for infectious diseases in general, a summary of the steps in its manufacture will now be given. A race of diphtheria bacilli, which has been found to yield a poison of great virulence in alkaline beef broth, is grown for a week or ten days in this medium. The toxin is then separated and its virulence exactly determined. It is preserved in sterile receptacles for immediate or future use."}]}
{"messages": [{"role": "assistant", "content": "It is preserved in sterile receptacles for immediate or future use. The next step is the inoculation of a suitable animal with the toxin. Of all animals the horse has been found to meet nearly every requirement. Such an animal, in a state of perfect health, receives an injection of twenty cubic centimetres of toxin, along with ten or fifteen of standard antitoxin, beneath the skin of the neck or fore-quarters, upon three separate occasions at intervals of five days. After this it receives increasing doses of toxin, alone, at intervals of six to eight days, until, at the end of two months, it is able to stand with little discomfort doses of such strength that if given in the first stage these doses would have quickly caused death. At this period the horse is bled to a small extent, and its serum tested to ascertain if prospects are good for the production by the animal of a high grade of antitoxin."}]}
{"messages": [{"role": "assistant", "content": "At this period the horse is bled to a small extent, and its serum tested to ascertain if prospects are good for the production by the animal of a high grade of antitoxin. If satisfactory progress has been made, the injections are continued for another month, when, as a rule, the maximal degree of antitoxic power in the serum will have been attained. The horse is now bled to the proper extent, the blood being received in a sterile jar and placed in an ice-box. Here it coagulates, and the serum separates from it. When the separation of clot and serum is complete, the latter is drawn off, taken to the laboratory, and standardized. This being finished, an antiseptic fluid is added to preserve the serum from decomposition."}]}
{"messages": [{"role": "assistant", "content": "This being finished, an antiseptic fluid is added to preserve the serum from decomposition. It is then bottled, labelled, and sent out for use. In similar fashion tetanus antitoxin is prepared; and quite recently Calmette has produced an antitoxic serum for use in snake bite, by injecting horses with minute increasing doses of snake venom. His experiments have given some remarkable results, not only in laboratory work, but also in cases of actual snake bite occurring in man. Thus bacteriological scientists, after years of laborious work, in the face of much criticism and severe denunciation, may confidently announce that they have in their possession a magic key to one of nature’s secret doors. The lock has been turned."}]}
{"messages": [{"role": "assistant", "content": "The lock has been turned. The door stands partly open, and we are permitted a glimpse of the future possibilities to be attained in the great fight against disease. PREVENTIVE MEDICINE \nThe following are some of the diseases which have been remarkably controlled through preventive medicine: \n_Small-pox._—While not a scourge of the first rank, like the plague or cholera, at the outset of the century variola was one of the most prevalent and dreaded of all diseases. Few reached adult life without an attack. To-day, though outbreaks still occur, it is a disease thoroughly controlled by vaccination. The protective power of the inoculated cow-pox is not a fixed and constant quantity."}]}
{"messages": [{"role": "assistant", "content": "The protective power of the inoculated cow-pox is not a fixed and constant quantity. The protection may be for life, or it may last only for a year or two. The all-important fact is this: That efficiently vaccinated persons may be exposed with impunity, and among large bodies of men (_e.g._, the German army), in which revaccination is practised, small-pox is unknown. Of one hundred vaccinated persons exposed to small-pox, possibly one might take the disease in a mild form; of one hundred unvaccinated persons so exposed, one alone might escape—from twenty-five to thirty would die. To be efficient, vaccination must be carried out systematically, and if all the inhabitants of this country were revaccinated at intervals small-pox would disappear (as it has from the German army), and the necessity for vaccination would cease. The difficulty arises from the constant presence of an unvaccinated remnant, by which the disease is kept alive."}]}
{"messages": [{"role": "assistant", "content": "The difficulty arises from the constant presence of an unvaccinated remnant, by which the disease is kept alive. The Montreal experience in 1885 is an object-lesson never to be forgotten. For eight or ten years vaccination had been neglected, particularly among the French-Canadians. On February 28, 1885, a Pullman car conductor, who came from Chicago, where the disease had been slightly prevalent, was admitted into the Hôtel Dieu. Isolation was not carried out, and on the 1st of April a servant in the hospital died of small-pox. Following her death the authorities of the hospital sent to their homes all patients who presented no symptoms of the disease."}]}
{"messages": [{"role": "assistant", "content": "Following her death the authorities of the hospital sent to their homes all patients who presented no symptoms of the disease. Like fire in dry grass the contagion spread, and within nine months there died of small-pox three thousand one hundred and sixty-four persons. It ruined the trade of the city for the winter, and cost millions of dollars. There are no reasonable objections to vaccination, which is a simple process, by which a mild and harmless disease is introduced. The use of the animal vaccine does away with the possibility of introduction of other disorders, such as syphilis. _Typhus Fever._—Until the middle of the present century this disease prevailed widely in most of the large cities, particularly in Europe, and also in jails, ships, hospitals, and camps."}]}
{"messages": [{"role": "assistant", "content": "_Typhus Fever._—Until the middle of the present century this disease prevailed widely in most of the large cities, particularly in Europe, and also in jails, ships, hospitals, and camps. It was more widely spread than typhoid fever and much more fatal. Murchison remarks of it that a complete history of its ravages would be the history of Europe during the past three centuries and a half. Not one of the acute infections seems to have been more dependent upon filth and unsanitary conditions. With the gradual introduction of drainage and a good water supply, and the relief of overcrowding, the disease has almost entirely disappeared, and is rarely mentioned now in the bills of mortality, except in a few of the larger and more unsanitary cities. The following figures illustrate what has been done in England within sixty years: In 1838 in England twelve hundred and twenty-eight persons died of fever (typhus and typhoid) per million of living."}]}
{"messages": [{"role": "assistant", "content": "The following figures illustrate what has been done in England within sixty years: In 1838 in England twelve hundred and twenty-eight persons died of fever (typhus and typhoid) per million of living. Twenty years later the figures were reduced to nine hundred and eighteen; in 1878 to three hundred and six of typhoid and to thirty-six of typhus fever. In 1892 only one hundred and thirty-seven died of typhoid fever and only three of typhus per million living! _Typhoid Fever._—While preventive medicine can claim a great victory in this disease also, it is less brilliant, since the conditions which favor its prevalence are not those specially relating to overcrowding as much as to imperfect water supply and the contamination of certain essential foods, as milk. It has been repeatedly demonstrated that, with a pure water supply and perfect drainage, typhoid fever almost disappears from a city. In Vienna, after the introduction of good water, the rate of mortality from typhoid fever fell from twelve per ten thousand of the inhabitants to about one."}]}
{"messages": [{"role": "assistant", "content": "In Vienna, after the introduction of good water, the rate of mortality from typhoid fever fell from twelve per ten thousand of the inhabitants to about one. In Munich the fall was still more remarkable; from above twenty-nine per ten thousand inhabitants in 1857 it fell to about one per ten thousand in 1887. That typhoid fever in this country is still a very prevalent disease depends mainly upon two facts: First, not only is the typhoid bacillus very resistant, but it may remain for a long time in the body of a person after recovery from typhoid fever, and such persons, in apparent good health, may be a source of contamination. With many of the conditions favoring the persistence and growth of the bacillus outside the body we are not yet familiar. The experience in the Spanish-American War illustrates how dangerous is the concentration together of large numbers of individuals. But, second, the essential factor in the widespread prevalence of typhoid fever in the United States, particularly in country districts, is the absence of anything like efficient rural sanitation."}]}
{"messages": [{"role": "assistant", "content": "But, second, the essential factor in the widespread prevalence of typhoid fever in the United States, particularly in country districts, is the absence of anything like efficient rural sanitation. Many counties have yet to learn the alphabet of sanitation. The chief danger results from the impure water supplies of the smaller towns, the local house epidemics due to infected wells, and the milk outbreaks due to the infection of dairy farms. The importance of scrupulously guarding the sources of supply was never better illustrated than in the well-known and oft-quoted epidemic in Plymouth, Pennsylvania. The town, with a population of eight thousand, was in part supplied with drinking-water from a reservoir fed by a mountain-stream. During January, February, and March, in a cottage by the side of and at a distance of from sixty to eighty feet from this stream, a man was ill with typhoid fever."}]}
{"messages": [{"role": "assistant", "content": "During January, February, and March, in a cottage by the side of and at a distance of from sixty to eighty feet from this stream, a man was ill with typhoid fever. The attendants were in the habit at night of throwing out the evacuations on the ground towards the stream. During these months the ground was frozen and covered with snow. In the latter part of March and early in April there was considerable rainfall and a thaw, in which a large part of the three months’ accumulation of discharges was washed into the brook not sixty feet distant. At the very time of this thaw the patient had numerous and copious discharges. About the 10th of April cases of typhoid fever broke out in the town, appearing for a time at the rate of fifty a day."}]}
{"messages": [{"role": "assistant", "content": "About the 10th of April cases of typhoid fever broke out in the town, appearing for a time at the rate of fifty a day. In all about twelve hundred were attacked. An immense majority of the cases were in the part of the town which received water from the infected reservoir. The use of boiled water and of ice made from distilled water, the systematic inspection of dairies, the scrupulous supervision of the sources from which the water is obtained, an efficient system of sewage removal, and, above all, the most scrupulous care on the part of physicians and of nurses in the disinfection of the discharges of typhoid fever patients—these are the factors necessary to reduce to a minimum the incidence of typhoid fever. _Cholera._—One of the great scourges of the present century made inroads into Europe and America from India, its native home. We have, however, found out the germ, found out the conditions under which it lives, and it is not likely that it will ever again gain a foothold in this country or Great Britain."}]}
{"messages": [{"role": "assistant", "content": "We have, however, found out the germ, found out the conditions under which it lives, and it is not likely that it will ever again gain a foothold in this country or Great Britain. Since the last epidemic, 1873, the disease, though brought to this country on several occasions, has always been held in check at the port of entry. It is communicated almost entirely through infected water, and the virulence of an epidemic in any city is in direct proportion to the imperfection of the water supply. This was shown in a remarkable way in the Hamburg epidemic of 1892. In Altona, which had a filtration plant, there were only five hundred and sixteen cases, many of them refugees from Hamburg. Hamburg, where the unfiltered water of the Elbe was used, had some eighteen thousand cases, with nearly eight thousand deaths."}]}
{"messages": [{"role": "assistant", "content": "Hamburg, where the unfiltered water of the Elbe was used, had some eighteen thousand cases, with nearly eight thousand deaths. _Yellow Fever._—The cause of this disease is still under discussion. It has an interest to us in this country from its continued prevalence in Cuba, and from the fact that at intervals it makes inroads into the Southern States, causing serious commercial loss. The history of the disease in the other West India islands, particularly Jamaica, indicates the steps which must be taken for its prevention. Formerly yellow fever was as fatal a scourge in them as it is to-day in Cuba. By an efficient system of sanitation it has been abolished."}]}
{"messages": [{"role": "assistant", "content": "By an efficient system of sanitation it has been abolished. The same can be done (and will be done) in Cuba within a few years. General Wood has already pointed out the way in the cleansing of Santiago. _The Plague._—One of the most remarkable facts in connection with modern epidemics has been the revival of the bubonic plague, the most dreaded of all the great infections. During the present century the disease in Europe has been confined almost exclusively to Turkey and Southern Europe. Since 1894, when it appeared at Hong-Kong, it has gradually spread, and there have been outbreaks of terrible severity in India."}]}
{"messages": [{"role": "assistant", "content": "Since 1894, when it appeared at Hong-Kong, it has gradually spread, and there have been outbreaks of terrible severity in India. It has extended to certain of the Mediterranean ports, and during the past summer it reached Glasgow, where there has been a small outbreak. On this hemisphere there have been small outbreaks in certain of the South American ports, cases have been brought to New York, and there have been to November 1st twenty-one cases among the Chinese in San Francisco. Judging from the readiness with which it has been checked and limited in Australia, and in particular the facility with which the recent outbreak in Glasgow has been stamped out, there is very little risk that plague will ever assume the proportions which gave to it its terrible reputation as the “black death” of the Middle Ages. As I have already mentioned, the germ is known, and prophylactic inoculations have been made on a large scale in India, with a certain measure of success. _Tuberculosis._—In all communities the _white plague_, as Oliver Wendell Holmes calls it, takes the first rank as a killing disease."}]}
{"messages": [{"role": "assistant", "content": "_Tuberculosis._—In all communities the _white plague_, as Oliver Wendell Holmes calls it, takes the first rank as a killing disease. It has been estimated that of it one hundred and twenty thousand people die yearly in this country. In all mortality bills tuberculosis of the lungs, or consumption, heads the list, and when to this is added tuberculosis of the other organs, the number swells to such an extent that this disease equals in fatality all the other acute infective diseases combined, if we leave out pneumonia. Less than twenty years ago we knew little or nothing of the cause of the disease. It was believed to be largely hereditary. Koch discovered the germ, and with this have come the possibilities of limiting its ravages."}]}
{"messages": [{"role": "assistant", "content": "Koch discovered the germ, and with this have come the possibilities of limiting its ravages. The following points with reference to it may be stated: In a few very rare instances the disease is transmitted from parent to child. In a large proportion of all cases the disease is “caught.” The germs are widely distributed through the sputum, which, when dry, becomes dust, and is blown about in all directions. Tubercle bacilli have been found in the dust of streets, houses, hospital wards, and much-frequented places. A single individual may discharge from the lungs countless myriads of germs in the twenty-four hours. Dr."}]}
{"messages": [{"role": "assistant", "content": "Dr. Nuttall estimated from a patient in the Johns Hopkins Hospital, who had only moderately advanced consumption, that from one and a half to four and a third billions of germs were thrown off in the twenty-four hours. The consumptive, as has been well stated, is almost harmless, and only becomes harmful through bad habits. The germs are contained in the sputum, which, when dry, is widely scattered in the form of dust, and constitutes the great medium for the transmission of the disease. If expectorated into a handkerchief, the sputum dries quickly, particularly if it is put into the pocket or under the pillow. The beard or mustache of a consumptive is smeared with the germs."}]}
{"messages": [{"role": "assistant", "content": "The beard or mustache of a consumptive is smeared with the germs. Even in the most careful the hands are apt to be soiled with the germs, and in those who are dirty and careless the furniture and materials which they handle readily become infected. Where the dirty habit prevails of spitting on the floor, a room, or the entire house, may contain numbers of germs. In the majority of all cases the infection in tuberculosis is by inhalation. This is shown by the frequency with which the disease is met in the lungs, and the great prevalence of tuberculosis in institutions in which the residents are restricted in the matter of fresh air and a free, open life. The disease prevails specially in cloisters, in jails, and in asylums."}]}
{"messages": [{"role": "assistant", "content": "The disease prevails specially in cloisters, in jails, and in asylums. Infection through milk is also possible; it is doubtful whether the disease is transmitted through meat. So widespread are the germs that post-mortem examination has shown that a very large number of persons show slight signs of the disease who have never during life presented any symptoms; in fact, some recent investigations would indicate that a very large proportion of all persons at the age of forty have somewhere in their bodies slight tuberculous lesions. This shows the importance of the individual predisposition, upon which the older writers laid so much stress, and the importance of maintaining the nutrition at its maximum. One of the most remarkable features of modern protective medicine is the widespread interest that has been aroused in the crusade against tuberculosis. What has already been accomplished warrants the belief that the hopes of even the most enthusiastic may be realized."}]}
{"messages": [{"role": "assistant", "content": "What has already been accomplished warrants the belief that the hopes of even the most enthusiastic may be realized. A positive decline in the prevalence of the disease has been shown in many of the larger cities during the past ten years. In Massachusetts, which has been a hot-bed of tuberculosis for many years, the death-rate has fallen from forty-two per ten thousand inhabitants in 1853 to twenty-one and eight-tenths per ten thousand inhabitants in 1895. In the city of Glasgow, in which the records have been very carefully kept, there has been an extraordinary fall in the death-rate from tuberculosis, and the recent statistics of New York City show, too, a similar remarkable diminution. In fighting the disease our chief weapons are: First, education of the public, particularly of the poorer classes, who do not fully appreciate the chief danger in the disease. Secondly, the compulsory notification and registration of all cases of tuberculosis."}]}
{"messages": [{"role": "assistant", "content": "Secondly, the compulsory notification and registration of all cases of tuberculosis. The importance of this relates chiefly to the very poor and improvident, from whom, after all, comes the greatest danger, and who should be under constant surveillance in order that these dangers may be reduced to a minimum. Thirdly, the foundation in suitable localities by the city and by the State of sanatoria for the treatment of early cases of the disease. Fourthly, provision for the chronic, incurable cases in special hospitals. _Diphtheria._—Since the discovery of the germ of this disease and our knowledge of the conditions of its transmission, and the discovery of the antitoxin, there has been a great reduction in its prevalence and an equally remarkable reduction in the mortality. The more careful isolation of the sick, the thorough disinfection of the clothing, the rigid scrutiny of the milder cases of throat disorder, a more stringent surveillance in the period of convalescence, and the routine examination of the throats of school-children—these are the essential measures by which the prevalence of the disease has been very markedly diminished."}]}
{"messages": [{"role": "assistant", "content": "The more careful isolation of the sick, the thorough disinfection of the clothing, the rigid scrutiny of the milder cases of throat disorder, a more stringent surveillance in the period of convalescence, and the routine examination of the throats of school-children—these are the essential measures by which the prevalence of the disease has been very markedly diminished. The great danger is in the mild cases, in which the disease has perhaps not been suspected, and in which the child may be walking about and even going to school. Such patients are often a source of widespread infection. The careful attention given by mothers to the teeth and mouth of children is also an important factor. In children with recurring attacks of tonsillitis, in whom the tonsils are enlarged, the organs should be removed. Through these measures the incidence of the disease has been very greatly reduced."}]}
{"messages": [{"role": "assistant", "content": "Through these measures the incidence of the disease has been very greatly reduced. _Pneumonia._—While there has been a remarkable diminution in the prevalence of a large number of all the acute infections, one disease not only holds its own, but seems even to have increased in its virulence. In the mortality bills, pneumonia is an easy second to tuberculosis. It attacks particularly the intemperate, the feeble, and the old, though every year a large number of robust, healthy individuals succumb. So frequent is pneumonia at advanced periods of life that to die of it has been said to be the natural end of old men in this country. In many ways, too, it is a satisfactory disease, if one may use such an expression."}]}
{"messages": [{"role": "assistant", "content": "In many ways, too, it is a satisfactory disease, if one may use such an expression. It is not associated with much pain, except at the onset, the battle is brief and short, and a great many old persons succumb to it easily and peacefully. We know the cause of the disease; we know only too well its symptoms, but the enormous fatality (from twenty to twenty-five per cent.) speaks only too plainly of the futility of our means of cure, and yet in no disease has there been so great a revolution in treatment. The patient is no longer drenched to death with drugs, or bled to a point where the resisting powers of nature are exhausted. We are not without hope, too, that in the future an antidote may be found to the toxins of the disease, and of late there have been introduced several measures of great value in supporting the weakness of the heart, a special danger in the old and debilitated. _Hydrophobia._—Rabies, a remarkable, and in certain countries a widespread, disease of animals, when transmitted to a man by the bite of rabid dogs, wolves, etc., is known as hydrophobia."}]}
{"messages": [{"role": "assistant", "content": "_Hydrophobia._—Rabies, a remarkable, and in certain countries a widespread, disease of animals, when transmitted to a man by the bite of rabid dogs, wolves, etc., is known as hydrophobia. The specific germ is unknown, but by a series of brilliant observations Pasteur showed (1) that the poison has certain fixed and peculiar properties in connection with the nervous system; (2) that susceptible animals could be rendered refractory to the disease, or incapable of taking it, by a certain method of inoculation; and (3) that an animal unprotected and inoculated with a dose of the virus sufficient to cause the disease may, by the injection of proper anti-rabic treatment, escape. Supported by these facts, Pasteur began a system of treatment of hydrophobia in man, and a special institute was founded in Paris for the purpose. When carried out promptly the treatment is successful in an immense majority of all cases, and the mortality in persons bitten by animals proved to be rabid, who have subsequently had the anti-rabic treatment, has been reduced to less than one-half per cent. The disease may be stamped out in dogs by careful quarantine of suspected animals, and by a thoroughly carried out muzzling order. _Malaria._—Among the most remarkable of modern discoveries is the cause of malarial fever, one of the great maladies of the world, and a prime obstacle to the settlement of Europeans in tropical regions."}]}
{"messages": [{"role": "assistant", "content": "_Malaria._—Among the most remarkable of modern discoveries is the cause of malarial fever, one of the great maladies of the world, and a prime obstacle to the settlement of Europeans in tropical regions. Until 1880 the cause was quite obscure. It was known that the disease prevailed chiefly in marshy districts, in the autumn, and that the danger of infection was greatest in the evening and at night, and that it was not directly contagious. In 1880 a French army surgeon, Laveran, discovered in the red blood-corpuscles small bodies which have proved to be the specific germ of the disease. They are not bacteria, but little animal bodies resembling the amœba—tiny little portions of protoplasm. The parasite in its earliest form is a small, clear, ring-shaped body inside the red blood-corpuscle, upon which it feeds, gradually increasing in size and forming within itself blackish grains out of the coloring matter of the corpuscle."}]}
{"messages": [{"role": "assistant", "content": "The parasite in its earliest form is a small, clear, ring-shaped body inside the red blood-corpuscle, upon which it feeds, gradually increasing in size and forming within itself blackish grains out of the coloring matter of the corpuscle. When the little parasite reaches a certain size it begins to divide or multiply, and an enormous number of these breaking up at the same time give off poison in the blood, which causes the paroxysms of fever. During what is known as the chill, in the intermittent fever, for example, one can always find these dividing parasites. Several different forms of the parasites have been found, corresponding to different varieties of malaria. Parasites of a very similar nature exist abundantly in birds. Ross, an army surgeon in India, found that the spread of this parasite from bird to bird was effected through the intervention of the mosquito."}]}
{"messages": [{"role": "assistant", "content": "Ross, an army surgeon in India, found that the spread of this parasite from bird to bird was effected through the intervention of the mosquito. The parasites reach maturity in certain cells of the coats of the stomach of these insects, and develop into peculiar thread-like bodies, many of which ultimately reach the salivary glands, from which, as the insect bites, they pass with the secretion of the glands into the wound. From this as a basis, numerous observers have worked out the relation of the mosquito to malaria in the human subject. Briefly stated, the disease is transmitted chiefly by certain varieties of the mosquito, particularly the _Anopheles_. The ordinary _Culex_, which is present chiefly in the Northern States, does not convey the disease. The _Anopheles_ sucks the blood from a person infected with malaria, takes in a certain number of parasites, which undergo development in the body of the insect, the final outcome of which is numerous small, thread-like structures, which are found in numbers in the salivary glands."}]}
{"messages": [{"role": "assistant", "content": "The _Anopheles_ sucks the blood from a person infected with malaria, takes in a certain number of parasites, which undergo development in the body of the insect, the final outcome of which is numerous small, thread-like structures, which are found in numbers in the salivary glands. From this point, when the mosquito bites another individual, they pass into his blood, infect the system, and in this way the disease is transmitted. Two very striking experiments may be mentioned. The Italian observers have repeatedly shown that _Anopheles_ which have sucked blood from patients suffering from malaria, when sent to a non-malarial region, and there allowed to bite perfectly healthy persons, have transmitted the disease. But a very crucial experiment was made a short time ago. Mosquitoes which had bitten malarial patients in Italy were sent to London and there allowed to bite Mr."}]}
{"messages": [{"role": "assistant", "content": "Mosquitoes which had bitten malarial patients in Italy were sent to London and there allowed to bite Mr. Manson, son of Dr. Manson, who really suggested the mosquito theory of malaria. This gentleman had not lived out of England, and there is no acute malaria in London. He had been a perfectly healthy, strong man. In a few days following the bites of the infected mosquitoes he had a typical attack of malarial fever."}]}
{"messages": [{"role": "assistant", "content": "In a few days following the bites of the infected mosquitoes he had a typical attack of malarial fever. The other experiment, though of a different character, is quite as convincing. In certain regions about Rome, in the Campania, malaria is so prevalent that in the autumn almost every one in the district is attacked, particularly if he is a new-comer. Dr. Sambron and a friend lived in this district from the 1st of June to the 1st of September, 1900. The test was whether they could live in this exceedingly dangerous climate for the three months without catching malaria, if they used stringent precautions against the bites of mosquitoes."}]}
{"messages": [{"role": "assistant", "content": "The test was whether they could live in this exceedingly dangerous climate for the three months without catching malaria, if they used stringent precautions against the bites of mosquitoes. For this purpose the hut in which they lived was thoroughly wired, and they slept with the greatest care under netting. Both of these gentlemen at the end of the period had escaped the disease. The importance of these studies cannot be overestimated. They explain the relation of malaria to marshy districts, the seasonal incidence of the disease, the nocturnal infection, and many other hitherto obscure problems. More important still, they point out clearly the way by which malaria may be prevented: First, the recognition that any individual with malaria is a source of danger in a community, so that he must be thoroughly treated with quinine; secondly, the importance of the draining of marshy districts and ponds in which mosquitoes breed; and, thirdly, that even in the most infected regions persons may escape the disease by living in thoroughly protected houses, in this way escaping the bites of mosquitoes."}]}
{"messages": [{"role": "assistant", "content": "More important still, they point out clearly the way by which malaria may be prevented: First, the recognition that any individual with malaria is a source of danger in a community, so that he must be thoroughly treated with quinine; secondly, the importance of the draining of marshy districts and ponds in which mosquitoes breed; and, thirdly, that even in the most infected regions persons may escape the disease by living in thoroughly protected houses, in this way escaping the bites of mosquitoes. _Venereal Diseases._—These continue to embarrass the social economist and to perplex and distress the profession. The misery and ill-health which they cause are incalculable, and the pity of it is that the cross is not always borne by the offender, but innocent women and children share the penalties. The gonorrhœal infection, so common, and often so little heeded, is a cause of much disease in parts other than those first affected. Syphilis claims its victims in every rank of life, at every age, and in all countries. We now treat it more thoroughly, but all attempts to check its ravages have been fruitless."}]}
{"messages": [{"role": "assistant", "content": "We now treat it more thoroughly, but all attempts to check its ravages have been fruitless. Physicians have two important duties: the incessant preaching of continence to young men, and scrupulous care, in every case, that the disease may not be a source of infection to others, and that by thorough treatment the patient may be saved from the serious late nervous manifestations. We can also urge that in the interests of public health venereal diseases, like other infections, shall be subject to supervision by the State. The opposition to measures tending to the restriction of these diseases is most natural: on the one hand, from women, who feel that it is an aggravation of a shocking injustice and wrong to their sex; on the other, from those who feel the moral guilt in a legal recognition of the evil. It is appalling to contemplate the frightful train of miseries which a single diseased woman may entail, not alone on her associates, but on scores of the innocent—whose bitter cry should make the opponents of legislation feel that any measures of restriction, any measures of registration, would be preferable to the present disgraceful condition, which makes of some Christian cities open brothels and allows the purest homes to be invaded by the most loathsome of all diseases. _Leprosy._—Since the discovery of the germ of this terrible disease systematic efforts have been made to improve the state of its victims and to promote the study of the conditions under which the disease prevails."}]}
{"messages": [{"role": "assistant", "content": "_Leprosy._—Since the discovery of the germ of this terrible disease systematic efforts have been made to improve the state of its victims and to promote the study of the conditions under which the disease prevails. The English Leprosy Commission has done good work in calling attention to the widespread prevalence of the disease in India and in the East. In this country leprosy has been introduced into San Francisco by the Chinese, and into the Northwestern States by the Norwegians, and there are foci of the disease in the Southern States, particularly Louisiana, and in the province of New Brunswick. The problem has an additional interest since the annexation of Hawaii and the Philippine Islands, in both of which places leprosy prevails extensively. By systematic measures of inspection and the segregation of affected individuals the disease can readily be held in check. It is not likely ever to increase among native Americans, or again gain such a foothold as it had in the Middle Ages."}]}
{"messages": [{"role": "assistant", "content": "It is not likely ever to increase among native Americans, or again gain such a foothold as it had in the Middle Ages. _Puerperal Fever._—Perhaps one of the most striking of all victories of preventive medicine has been the almost total abolition of so-called child-bed fever from the maternity hospitals and from private practice. In many institutions the mortality after child-birth was five or six per cent., indeed sometimes as high as ten per cent., whereas to-day, owing entirely to proper antiseptic precautions, the mortality has fallen to three-tenths to four-tenths per cent. The recognition of the contagiousness of puerperal fever was the most valuable contribution to medical science made by Oliver Wendell Holmes. There had been previous suggestions by several writers, but his essay on the “Contagiousness of Puerperal Fever,” published in 1843, was the first strong, clear, logical statement of the case. Semmelweis, a few years later, added the weight of a large practical experience to the side of the contagiousness, but the full recognition of the causes of the disease was not reached until the recent antiseptic views had been put into practical effect."}]}
{"messages": [{"role": "assistant", "content": "Semmelweis, a few years later, added the weight of a large practical experience to the side of the contagiousness, but the full recognition of the causes of the disease was not reached until the recent antiseptic views had been put into practical effect. THE NEW DISPENSATION IN TREATMENT \nThe century has witnessed a revolution in the treatment of disease, and the growth of a new school of medicine. The old schools—regular and homœopathic—put their trust in drugs, to give which was the alpha and the omega of their practice. For every symptom there were a score or more of medicines—vile, nauseous compounds in one case; bland, harmless dilutions in the other. The new school has a firm faith in a few good, well-tried drugs, little or none in the great mass of medicines still in general use. Imperative drugging—the ordering of medicine in any and every malady—is no longer regarded as the chief function of the doctor."}]}
{"messages": [{"role": "assistant", "content": "Imperative drugging—the ordering of medicine in any and every malady—is no longer regarded as the chief function of the doctor. Naturally, when the entire conception of the disease was changed, there came a corresponding change in our therapeutics. In no respect is this more strikingly shown than in our present treatment of fever—say, of the common typhoid fever. During the first quarter of the century the patients were bled, blistered, purged and vomited, and dosed with mercury, antimony, and other compounds to meet special symptoms. During the second quarter, the same, with variations in different countries. After 1850 bleeding became less frequent, and the experiments of the Paris and Vienna schools began to shake the belief in the control of fever by drugs."}]}
{"messages": [{"role": "assistant", "content": "After 1850 bleeding became less frequent, and the experiments of the Paris and Vienna schools began to shake the belief in the control of fever by drugs. During the last quarter sensible doctors have reached the conclusion that typhoid fever is not a disease to be treated with medicines, but that in a large proportion of all cases diet, nursing, and bathing meet the indications. There is active, systematic, careful, watchful treatment, but not with drugs. The public has not yet been fully educated to this point, and medicines have sometimes to be ordered for the sake of the friends, and it must be confessed that there are still in the ranks _antiques_ who would insist on a dose of some kind every few hours. The battle against poly-pharmacy, or the use of a large number of drugs (of the action of which we know little, yet we put them into bodies of the action of which we know less), has not been fought to a finish. There have been two contributing factors on the side of progress—the remarkable growth of the skeptical spirit fostered by Paris, Vienna, and Boston physicians, and, above all, the valuable lesson of homœopathy, the infinitesimals of which certainly could not do harm, and quite as certainly could not do good; yet nobody has ever claimed that the mortality among homœopathic practitioners was greater than among those of the regular school."}]}
{"messages": [{"role": "assistant", "content": "There have been two contributing factors on the side of progress—the remarkable growth of the skeptical spirit fostered by Paris, Vienna, and Boston physicians, and, above all, the valuable lesson of homœopathy, the infinitesimals of which certainly could not do harm, and quite as certainly could not do good; yet nobody has ever claimed that the mortality among homœopathic practitioners was greater than among those of the regular school. A new school of practitioners has arisen which cares nothing for homœopathy and less for so-called allopathy. It seeks to study, rationally and scientifically, the action of drugs, old and new. It is more concerned that a physician shall know how to apply the few great medicines which all have to use, such as quinine, iron, mercury, iodide of potassium, opium, and digitalis, rather than a multiplicity of remedies the action of which is extremely doubtful. The growth of scientific pharmacology, by which we now have many active principles instead of crude drugs, and the discovery of the art of making medicines palatable, have been of enormous aid in rational practice. There is no limit to the possibility of help from the scientific investigation of the properties and action of drugs."}]}
{"messages": [{"role": "assistant", "content": "There is no limit to the possibility of help from the scientific investigation of the properties and action of drugs. At any day the new chemistry may give to us remedies of extraordinary potency and of as much usefulness as cocaine. There is no reason why we should not even in the vegetable world find for certain diseases specifics of virtue fully equal to that of quinine in the malarial fevers. One of the most striking characteristics of the modern treatment of disease is the return to what used to be called the natural methods—diet, exercise, bathing, and massage. There probably never has been a period in the history of the profession when the value of _diet_ in the prevention and the cure of disease was more fully recognized. Dyspepsia, the besetting malady of this country, is largely due to improper diet, imperfectly prepared and too hastily eaten."}]}
{"messages": [{"role": "assistant", "content": "Dyspepsia, the besetting malady of this country, is largely due to improper diet, imperfectly prepared and too hastily eaten. One of the great lessons to be learned is that the preservation of health depends in great part upon food well cooked and carefully eaten. A common cause of ruined digestion, particularly in young girls, is the eating of sweets between meals and the drinking of the abominations dispensed in the chemists’ shops in the form of ice-cream sodas, etc. Another frequent cause of ruined digestion in business men is the hurried meal at the lunch-counter. And a third factor, most important of all, illustrates the old maxim, that more people are killed by over eating and drinking than by the sword. Sensible people have begun to realize that alcoholic excesses lead inevitably to impaired health."}]}
{"messages": [{"role": "assistant", "content": "Sensible people have begun to realize that alcoholic excesses lead inevitably to impaired health. A man may take four or five drinks of whiskey a day, or even more, and thinks perhaps that he transacts his business better with that amount of stimulant; but it only too frequently happens that early in the fifth decade, just as business or political success is assured, Bacchus hands in heavy bills for payment, in the form of serious disease of the arteries or of the liver, or there is a general breakdown. With the introduction of light beer there has been not only less intemperance, but a reduction in the number of the cases of organic disease of the heart, liver, and stomach caused by alcohol. While temperance in the matter of alcoholic drinks is becoming a characteristic feature of Americans, intemperance in the quantity of food taken is almost the rule. Adults eat far too much, and physicians are beginning to recognize that the early degenerations, particularly of the arteries and of the kidneys, leading to Bright’s disease, which were formerly attributed to alcohol, are due in large part to too much food. _Nursing._—Perhaps in no particular does nineteenth-century practice differ from that of the preceding centuries more than in the greater attention which is given to the personal comfort of the patient and to all the accessories comprised in the art of nursing."}]}
{"messages": [{"role": "assistant", "content": "_Nursing._—Perhaps in no particular does nineteenth-century practice differ from that of the preceding centuries more than in the greater attention which is given to the personal comfort of the patient and to all the accessories comprised in the art of nursing. The physician has in the trained nurse an assistant who carries out his directions with a watchful care, and who is on the lookout for danger-signals, and with accurate notes enables him to estimate the progress of a critical case from hour to hour. The intelligent, devoted women who have adopted the profession of nursing, are not only in their ministrations a public benefaction, but they have lightened the anxieties which form so large a part of the load of the busy doctor. _Massage and Hydrotherapy_ have taken their places as most important measures of relief in many chronic conditions, and the latter has been almost universally adopted as the only safe means of combating the high temperatures of the acute fevers. Within the past quarter of a century the value of _exercise_ in the education of the young has become recognized. The increase in the means of taking wholesome out-of-door exercise is remarkable, and should show in a few years an influence in the reduction of the nervous troubles in young persons."}]}
{"messages": [{"role": "assistant", "content": "The increase in the means of taking wholesome out-of-door exercise is remarkable, and should show in a few years an influence in the reduction of the nervous troubles in young persons. The prophylactic benefit of systematic exercise, taken in moderation by persons of middle age, is very great. Golf and the bicycle have in the past few years materially lowered the average incomes of the doctors in this country as derived from persons under forty. From the senile contingent—those above this age—the average income has for a time been raised by these exercises, as a large number of persons have been injured by taking up sports which may be vigorously pursued with safety only by those with young arteries. Of three departures in the art of healing, brief mention may be made. The use of the extracts of certain organs (or of the organs themselves) in disease is as old as the days of the Romans, but an extraordinary impetus has been given to the subject by the discovery of the curative powers of the extract of the thyroid gland in the diseases known as cretinism and myxœdema."}]}
{"messages": [{"role": "assistant", "content": "The use of the extracts of certain organs (or of the organs themselves) in disease is as old as the days of the Romans, but an extraordinary impetus has been given to the subject by the discovery of the curative powers of the extract of the thyroid gland in the diseases known as cretinism and myxœdema. The brilliancy of the results in these diseases has had no parallel in the history of modern medicine, but it cannot be said that in the use of the extracts of other organs for disease the results have fulfilled the sanguine expectations of many. There was not, in the first place, the same physiological basis, and practitioners have used these extracts too indiscriminately and without sufficient knowledge of the subject. Secondly, as I have already mentioned, we possess a sure and certain hope that for many of the acute infections antitoxins will be found. A third noteworthy feature in modern treatment has been a return to psychical methods of cure, in which _faith in something is suggested_ to the patient. After all, faith is the great lever of life."}]}
{"messages": [{"role": "assistant", "content": "After all, faith is the great lever of life. Without it, man can do nothing; with it, even with a fragment, as a grain of mustard-seed, all things are possible to him. Faith in us, faith in our drugs and methods, is the great stock in trade of the profession. In one pan of the balance, put the pharmacopœias of the world, all the editions from Dioscorides to the last issue of the United States Dispensatory; heap them on the scales as did Euripides his books in the celebrated contest in the “Frogs”; in the other put the simple faith with which from the days of the Pharaohs until now the children of men have swallowed the mixtures these works describe, and the bulky tomes will kick the beam. It is the _aurum potabile_, the touchstone of success in medicine. As Galen says, confidence and hope do more good than physic—“he cures most in whom most are confident.” That strange compound of charlatan and philosopher, Paracelsus, encouraged his patients “to have a good faith, a strong imagination, and they shall find the effects” (Burton)."}]}
{"messages": [{"role": "assistant", "content": "As Galen says, confidence and hope do more good than physic—“he cures most in whom most are confident.” That strange compound of charlatan and philosopher, Paracelsus, encouraged his patients “to have a good faith, a strong imagination, and they shall find the effects” (Burton). While we often overlook or are ignorant of our own faith-cures, doctors are just a wee bit too sensitive about those performed outside our ranks. They have never had, and cannot expect to have, a monopoly in this panacea, which is open to all, free as the sun, and which may make of every one in certain cases, as was the Lacedemon of Homer’s day, “a good physician out of Nature’s grace.” Faith in the gods or in the saints cures one, faith in little pills another, hypnotic suggestion a third, faith in a plain, common doctor a fourth. In all ages the prayer of faith has healed the sick, and the mental attitude of the suppliant seems to be of more consequence than the powers to which the prayer is addressed. The cures in the temples of Æsculapius, the miracles of the saints, the remarkable cures of those noble men, the Jesuit missionaries, in this country, the modern miracles at Lourdes and at St. Anne de Beaupré in Quebec, and the wonder-workings of the so-called Christian Scientists, are often genuine, and must be considered in discussing the foundations of therapeutics."}]}
{"messages": [{"role": "assistant", "content": "Anne de Beaupré in Quebec, and the wonder-workings of the so-called Christian Scientists, are often genuine, and must be considered in discussing the foundations of therapeutics. We physicians use the same power every day. If a poor lass, paralyzed, apparently, helpless, bed-ridden for years, comes to me, having worn out in mind, body, and estate a devoted family; if she in a few weeks or less by faith in me, and faith alone, takes up her bed and walks, the saints of old could not have done more. St. Anne and many others can scarcely to-day do less. We enjoy, I say, no monopoly in the faith business."}]}
{"messages": [{"role": "assistant", "content": "We enjoy, I say, no monopoly in the faith business. The faith with which we work, the faith, indeed, which is available to-day in every-day life, has its limitations. It will not raise the dead; it will not put in a new eye in place of a bad one (as it did to an Iroquois Indian boy for one of the Jesuit fathers), nor will it cure cancer or pneumonia, or knit a bone; but, in spite of these nineteenth-century restrictions, such as we find it, faith is a most precious commodity, without which we should be very badly off. _Hypnotism_, introduced by Mesmer in the eighteenth century, has had several revivals as a method of treatment during the nineteenth century. The first careful study of it was made by Braid, a Manchester surgeon, who introduced the terms hypnotism, hypnotic, and nervous sleep; but at this time no very great measure of success followed its use in practice, except perhaps in the case of an Anglo-Indian surgeon, James Esdaile, who, prior to the introduction of anæsthesia, had performed two hundred and sixty-one surgical operations upon patients in a state of hypnotic unconsciousness. About 1880 the French physicians, particularly Charcot and Bernheim, took up the study, and since that time hypnotism has been extensively practised."}]}
{"messages": [{"role": "assistant", "content": "About 1880 the French physicians, particularly Charcot and Bernheim, took up the study, and since that time hypnotism has been extensively practised. It may be defined as a subjective psychical condition, what Braid called nervous sleep, resembling somnambulism, in which, as Shakespeare says, in the description of Lady Macbeth, the person receives at once the benefit of sleep and does the effects or acts of watching or waking. Therapeutically, the important fact is that the individual’s natural susceptibility to suggestion is increased, and this may hold after the condition of hypnosis has passed away. The condition of hypnosis is usually itself induced by suggestion, requesting the subject to close the eyes, to think of sleep, and the operator then repeats two or three times sentences suggesting sleep, and suggesting that the limbs are getting heavy and that he is feeling drowsy. During this state it has been found that the subjects are very susceptible to suggestion. Too much must not be expected of hypnotism, and the claims which have been made for it have been too often grossly exaggerated."}]}
{"messages": [{"role": "assistant", "content": "Too much must not be expected of hypnotism, and the claims which have been made for it have been too often grossly exaggerated. It seems, as it has been recently well put, that hypnotism “at best permits of making suggestions more effective for good or bad than can be done upon one in his waking state.” It is found to be of very little use in organic disease. It has been helpful in some cases of hysteria, in certain functional spasmodic affections of the nervous system, in the vicious habits of childhood, and in suggesting to the victims of alcohol and drugs that they should get rid of their inordinate desires. It has been used successfully in certain cases for the relief of labor pains, and in surgical operations; but on the whole, while a valuable agent in a few cases, it has scarcely fulfilled the expectations of its advocates. It is a practice not without serious dangers, and should never be performed except in the presence of a third person, and its indiscriminate practice by ignorant persons should be prevented by law. One mode of faith-healing in modern days, which passes under the remarkable name of Christian Science, is probably nothing more than mental suggestion under another name."}]}
{"messages": [{"role": "assistant", "content": "One mode of faith-healing in modern days, which passes under the remarkable name of Christian Science, is probably nothing more than mental suggestion under another name. “The patient is told to be calm, and is assured that all will go well; that he must try to aid the healer by believing that what is told him is true. The healer then, quietly but firmly, asserts and reiterates that there is no pain, no suffering, that it is disappearing, that relief will come, that the patient is getting well.” This is precisely the method which Bernheim used to use with such success in his hypnotic patients at Nancy, iterating and reiterating, in a most wearisome way, that the disease would disappear and the patient would feel better. As has been pointed out by a recent writer (Dr. Harry Marshall), the chief basis for the growth of Christian Science is that which underlies every popular fallacy: “Oliver Wendell Holmes outlined very clearly the factors concerned, showing (a) how easily abundant facts can be collected to prove anything whatsoever; (b) how insufficient ‘exalted wisdom, immaculate honesty, and vast general acquirements’ are to prevent an individual from having the most primitive ideas upon subjects out of his line of thought; and, finally, demonstrating ‘the boundless credulity and excitability of mankind upon subjects connected with medicine.’” \n            WILLIAM OSLER. SURGERY \n\nThe end of the eighteenth century was made notable by one of the most remarkable and beneficent discoveries which has ever blessed the human race, the discovery of the means of preventing small-pox."}]}
{"messages": [{"role": "assistant", "content": "SURGERY \n\nThe end of the eighteenth century was made notable by one of the most remarkable and beneficent discoveries which has ever blessed the human race, the discovery of the means of preventing small-pox. On May 14, 1796, Dr. Edward Jenner inoculated James Phipps. When we remember that two million persons died in a single year in the Russian Empire from small-pox; that in 1707 in Iceland, out of a population of thirty thousand, sixty per cent., or eighteen thousand, died; that in Jenner’s time “an adult person who had not had small-pox was scarcely met with or heard of in the United Kingdom, and that owing to his discovery small-pox is now one of the rarest diseases,” the strong words I have used seem fully justified. But the eighteenth century was not to witness the end of progress in medicine. The advances in the nineteenth century have been even more startling and more beneficent."}]}
{"messages": [{"role": "assistant", "content": "The advances in the nineteenth century have been even more startling and more beneficent. What these advances have been in the department of medicine has been related by Professor Osler. It is my province to speak only of surgery. METHOD OF TEACHING \nThe first advance which should be mentioned is a fundamental one—namely, methods of medical teaching. At the beginning of the nineteenth century there were only three medical schools in the United States: the Medical Department of the University of Pennsylvania, established in 1765; the Medical Department of Harvard, established in 1783; and the Medical Department of Dartmouth, established in 1797. The last report of the Commissioner of Education gives a list of one hundred and fifty-five medical schools now in existence in this country, many of them still poorly equipped and struggling for existence, but a large number of them standing in the first rank, with excellent modern equipment, both in teachers, laboratories, hospitals, and other facilities."}]}
{"messages": [{"role": "assistant", "content": "The last report of the Commissioner of Education gives a list of one hundred and fifty-five medical schools now in existence in this country, many of them still poorly equipped and struggling for existence, but a large number of them standing in the first rank, with excellent modern equipment, both in teachers, laboratories, hospitals, and other facilities. The medical curriculum then extended over only two years or less, and consisted of courses of lectures at the most by seven professors who, year after year, read the same course of lectures, without illustrations and with no practical teaching. The medical schools, even when connected with universities, were practically private corporations, the members of which took all the fees, spent what money they were compelled to spend in the maintenance of what we now should call the semblance of an education, and divided the profits. Until within about twenty years this method prevailed in all our medical schools. But the last two decades of the century have seen a remarkable awakening of the medical profession to the need of a broader and more liberal education, and that, as a prerequisite, the medical schools should be on the same basis as the department of arts in every well-regulated college. To accomplish this the boards of trustees have taken possession of the fees of students, have placed the faculties upon salaries, and have used such portion of the incomes of the institutions as was needed for a constant and yet rapid development along the most liberal lines."}]}
{"messages": [{"role": "assistant", "content": "To accomplish this the boards of trustees have taken possession of the fees of students, have placed the faculties upon salaries, and have used such portion of the incomes of the institutions as was needed for a constant and yet rapid development along the most liberal lines. COLLEGE HOSPITALS \nThe first step has been the establishment in connection with most schools of general hospitals in which the various teachers in the college should be the clinical instructors, and where the students would have the means not only of hearing theoretically what should be done to the sick, but of actually examining the patients under the supervision of their instructors, studying the cases so as to become skilled in reaching a diagnosis and indicating what in their opinion was necessary in the way either of hygiene, medicine, or surgical operation. More than that, in most of the advanced schools to-day the students assist the clinical faculties of the hospitals in the actual performance of operations, so that when they graduate they are skilled to a degree utterly unknown twenty years ago. ESTABLISHMENT OF LABORATORIES \nAnother step which was equally important, and in some respects even more so, has been the establishment of laboratories connected with each branch of instruction. A laboratory of anatomy (the dissecting room) every medical school has always had, but all the other laboratories are recent additions. Among these may be named a laboratory of clinical medicine, a laboratory of therapeutics, in which the action of drugs is studied; a laboratory of chemistry, a laboratory of microscopy, a laboratory of pathology for the study of diseased tissues, a laboratory of embryology for the study of the development of the human body and of the embryos of animals, a laboratory of hygiene, a laboratory of bacteriology, a laboratory of pharmacy, a surgical laboratory, in which all the operations of surgery are done on the cadaver by each student, a laboratory of physiology, and in many colleges private rooms in which advanced work may be done for the discovery of new truths."}]}
{"messages": [{"role": "assistant", "content": "Among these may be named a laboratory of clinical medicine, a laboratory of therapeutics, in which the action of drugs is studied; a laboratory of chemistry, a laboratory of microscopy, a laboratory of pathology for the study of diseased tissues, a laboratory of embryology for the study of the development of the human body and of the embryos of animals, a laboratory of hygiene, a laboratory of bacteriology, a laboratory of pharmacy, a surgical laboratory, in which all the operations of surgery are done on the cadaver by each student, a laboratory of physiology, and in many colleges private rooms in which advanced work may be done for the discovery of new truths. In all these laboratories, instead of simply hearing about the experiments and observations, each student is required to handle the drugs, the chemicals, the apparatus, to do all the operations, to look through the microscope, etc.; in other words, to do all that which is necessary for the proper understanding of the case in hand. In fact, it may be said that in view of the opportunities and the requirements of modern hospitals, it is undoubtedly true that a hospital patient, the poorest of the poor, often has his case more thoroughly studied and more accurately observed than the wealthy patient who is attended at his home. On the other hand, however, so many laboratories with their expensive apparatus and a large staff of assistants mean an enormous increase in the expense of a medical education, for which the student does not pay anything like an equivalent. Hence the need in all of our best modern medical schools for endowments, in order that such work may be carried on properly, and yet the student not be charged such fees as to be practically prohibitory, excepting for the rich, or at the least the well-to-do. I do not hesitate to say that at the end of the second year many a diligent student of to-day is better fitted to practise medicine than was the graduate of half a century ago."}]}
{"messages": [{"role": "assistant", "content": "I do not hesitate to say that at the end of the second year many a diligent student of to-day is better fitted to practise medicine than was the graduate of half a century ago. ANATOMICAL MATERIAL \nOne of the most important means of the study of medicine, and especially of surgery, is a thorough acquaintance with the anatomy of the human body. No one would think of placing an engineer in charge of a complicated piece of machinery, who had never become intimately acquainted with all the parts of such a machine, so that he could take it to pieces and put it together again with ease and intelligence. Yet, until comparatively recently, this knowledge of anatomy was both required of, and yet at the same time the means of obtaining it was forbidden to, the medical student. If he performed an operation and was guilty of negligence or error, due to his want of anatomical knowledge, he was liable to a suit for malpractice. Yet his only means of becoming acquainted with the anatomy of the human body was by stealing the bodies of the dead."}]}
{"messages": [{"role": "assistant", "content": "Yet his only means of becoming acquainted with the anatomy of the human body was by stealing the bodies of the dead. In England, up to 1832, this was equally true. A regular traffic in human bodies existed there as well as here, and, by reason of its perils, the cost of bodies for dissection was very great; but it was only a question of money. In his testimony before the Parliamentary Committee, Sir Astley Cooper made a shiver run down the backs of the noble lords who listened to him when he said that in order to dissect the body of any of them it was only necessary for him to pay enough. The large pecuniary profits of such business, when the supply was very small, led to the horrible atrocities of Burke and Hare in Edinburgh in 1832. They deliberately murdered a considerable number of persons, and sold the bodies to the dissecting rooms in that city."}]}
{"messages": [{"role": "assistant", "content": "They deliberately murdered a considerable number of persons, and sold the bodies to the dissecting rooms in that city. The discovery of their crimes finally led to the passage of the Anatomy Act, which has been in force in Great Britain ever since. Similar violations of graveyards in this country have led to the passage in various States of somewhat similar laws, usually giving for dissection the bodies of those who were so poor in friendship that no one would spend the money necessary for their burial. Even to-day, in a large number of our States, the former anomalous condition of affairs exists. The increase of anatomical material which has resulted from the enactment of wise and salutary laws for this purpose has given a great impetus to the study of anatomy, and has produced a far better educated class of physicians in most parts of the United States within the last few years. The enlightened sense of the community has perceived that to deny the medical schools the means of properly teaching anatomy was a fatal mistake, and resulted in an ignorance of which the community were the victims."}]}
{"messages": [{"role": "assistant", "content": "The enlightened sense of the community has perceived that to deny the medical schools the means of properly teaching anatomy was a fatal mistake, and resulted in an ignorance of which the community were the victims. As a result, it is possible now, by law, in most States to obtain a reasonable number of cadavers, not only for the study of anatomy, but for the performance of all the usual operations. MEDICAL LIBRARIES \nAlong with this there has been throughout this country a marked movement in favor of medical libraries. It is to the credit of the government of the United States that the whole world is debtor to us, not only for the foremost medical library in the world, that of the surgeon-general of the army in Washington, but also for the magnificent index-catalogue, not only of the books, but all the journal articles in every language in the world. No better investment of money was ever made than the establishment of this library, and its allied museum, and the publication of the index-catalogue. EMBRYOLOGY \nAs a result of all these means and methods of study, and as a part of the great educational and scientific movement of the century, medical men now take a wholly different view of the normal and abnormal structures of the human body."}]}
{"messages": [{"role": "assistant", "content": "EMBRYOLOGY \nAs a result of all these means and methods of study, and as a part of the great educational and scientific movement of the century, medical men now take a wholly different view of the normal and abnormal structures of the human body. The study of embryology has shown us that many of the deviations from the normal development of the human body are easily explained by embryology. One of the most important changes in our idea, for example, of tumors is due to the fact that the study of embryology and of the tissues of the embryo have shown us that diseased structures, which lack explanation entirely, when compared with the adult human tissues, readily find their explanation and fall into an unexpected order when compared with the tissues of the embryo. Not only, however, has the study of embryological tissues thrown a flood of light on diseased structures, but we have obtained new views of the relation of man to all creatures, lower in the scale of life. Largely owing to the doctrine of evolution, we now recognize the fact that, so far as his body is concerned, man is kindred to the brutes; that his diseases, within certain limitations, are identical with similar diseases of the lower animals; that his anatomy and physiology are, in essence, the same as the anatomy and physiology of the lower animals, even the very lowest, and that many of his diseases can be best studied in the lower animals, because upon them we can make exact experiments which would be impossible in man. While it is true that each animal has disorders which are peculiar to itself, and that it is not subject to some of the disorders to which man is a victim, and, _per contra_, that man is a victim to some disorders from which animals do not suffer, yet, taking them as a whole, the diseases of man and of animals, and the action of remedies on both, are practically identical."}]}
{"messages": [{"role": "assistant", "content": "While it is true that each animal has disorders which are peculiar to itself, and that it is not subject to some of the disorders to which man is a victim, and, _per contra_, that man is a victim to some disorders from which animals do not suffer, yet, taking them as a whole, the diseases of man and of animals, and the action of remedies on both, are practically identical. To this I shall have occasion to refer again. PATHOLOGY \nAmong the laboratories which I mentioned, one of the most important is that of pathology and morbid anatomy, or the study of diseased tissues and organs. The first work on pathology written in this country was by one of our best-known surgeons, the late Samuel D. Gross, and one of his most important contributions to surgical progress consisted in his persistent advocacy of the need for the study of pathology as a basis for all our means of cure. This is evident, if we consider the illustration I used a moment ago of a steam-engine."}]}
{"messages": [{"role": "assistant", "content": "This is evident, if we consider the illustration I used a moment ago of a steam-engine. Unless he knows precisely the defects of such a machine, the influence of fresh or salt water on a boiler, the influence of rust, the effect of oils, entirely apart from the mere mechanism of the engine, an engineer might make the most serious mistake, resulting in fatal damage, both to the machine and probably to life. So, surgical pathology is the study of the processes of disease, the alterations in the minute structure of tissues and organs, without which no surgeon can be fitted for his task, much less can he be called an accomplished surgeon. All of these laboratories mark the difference between the scientific and the empirical method. The old student of medicine went from case to case, heard many a good maxim, and learned many a useful trick; but, after all, it was only an empirical knowledge which he obtained. It did not go to the foundation of things, it was not scientific, as is the collegiate instruction of to-day."}]}
{"messages": [{"role": "assistant", "content": "It did not go to the foundation of things, it was not scientific, as is the collegiate instruction of to-day. Having now glanced rapidly at the improvement in medical instruction, let me turn next to a few of the principal discoveries which have made the surgery of to-day so much superior to the surgery of a hundred years ago. ANÆSTHESIA \nAfter vaccination, the most important medical event of the century is the discovery of anæsthesia. While there were some prior attempts at anæsthesia, practically it dates from October 16, 1846, when Dr. John C. Warren, in the Massachusetts General Hospital, first performed a major surgical operation, without inflicting the slightest pain."}]}
{"messages": [{"role": "assistant", "content": "Warren, in the Massachusetts General Hospital, first performed a major surgical operation, without inflicting the slightest pain. I cannot enter into the merits of the various claimants for the credit of first using an anæsthetic, but ether was then for the first time publicly administered by Morton, and the very sponge which was then used is now a precious trophy of the Massachusetts General Hospital. I may, perhaps, quote from an address which I delivered before the Medical and Chirurgical Faculty of the State of Maryland, at their centennial anniversary, in April, 1899, the following in relation to anæsthesia: \n    “The news went like wildfire, and anæsthesia was soon introduced     into every clinic and at almost every operation throughout     the civilized world. Prior to that time a surgical operation     was attended with horrors which those who live in these days     cannot appreciate. He was the best surgeon who could perform any     operation in the least possible time. The whole object of new     methods of operating was to shorten the period of frightful agony     which every patient had to endure."}]}
{"messages": [{"role": "assistant", "content": "The whole object of new     methods of operating was to shorten the period of frightful agony     which every patient had to endure. Every second of suffering     saved was an incalculable boon. To submit to any operation     required then a heroism and an endurance which is almost     incomprehensible to us now. All of the more modern, deliberate,     careful, painstaking operations, involving minute dissection,     amid nerves and blood-vessels, when life or death depends on the     accuracy of almost every touch of the knife, were absolutely     impossible. It was beyond human endurance quietly to submit one’s     self for an hour, for an hour and a half, for two hours, or even     longer, to such physical agony. “It is a striking commentary on the immediate results of     anæsthesia to learn that, in five years before the introduction     of ether, only one hundred and eighty-four persons were     willing to submit themselves to such a dreadful ordeal in the     Massachusetts General Hospital—an average of thirty-seven     operations per annum, or three per month...."}]}
{"messages": [{"role": "assistant", "content": "“It is a striking commentary on the immediate results of     anæsthesia to learn that, in five years before the introduction     of ether, only one hundred and eighty-four persons were     willing to submit themselves to such a dreadful ordeal in the     Massachusetts General Hospital—an average of thirty-seven     operations per annum, or three per month.... During the last     year, in the same hospital—a Mecca for every surgeon the world     over—over thirty-seven hundred operations were performed. It is     not an uncommon thing at the present day for any one of the more     active surgeons of this country to do as many as four or five     hundred operations in a year. I have known as many as nineteen     operations to be done in the Jefferson Medical College Hospital     in a single day—equalling six months’ work in Boston before the     introduction of ether.” \nThe next year, 1847, witnessed the introduction of chloroform by Sir James Y. Simpson, of Edinburgh. Until I became acquainted with the striking figures just quoted, I had often wondered at the hospital scene in that most touching story, _Rab and His Friends_, by the late gifted and well-beloved physician, Dr."}]}
{"messages": [{"role": "assistant", "content": "Until I became acquainted with the striking figures just quoted, I had often wondered at the hospital scene in that most touching story, _Rab and His Friends_, by the late gifted and well-beloved physician, Dr. John Brown, of Edinburgh. Nowadays students do not rush into the surgical amphitheatre when they learn that an operation is to be done, but it is taken as a matter of course, for practically every day many operations are done in most of our large hospitals. But, at the time when Rab’s mistress was operated upon, an operation, as has been stated, was a very rare event. Few had the fortitude to endure its dreadful pangs. Now, thanks to the blessed sleep of anæsthesia, sufferers from even the most dreadful disorders can have long and difficult operations done, accurate and tedious dissections made, and yet feel not a twinge of pain."}]}
{"messages": [{"role": "assistant", "content": "Now, thanks to the blessed sleep of anæsthesia, sufferers from even the most dreadful disorders can have long and difficult operations done, accurate and tedious dissections made, and yet feel not a twinge of pain. Besides general anæsthesia by ether, chloroform, and a few other agents, there have been introduced several means for producing “local anæsthesia,” _i.e._, agents which destroy the sensibility of the part of the body to be operated upon while not producing unconsciousness. Freezing the part by ice and salt, or by a quickly evaporating spray of rhigolene or chloride of ethyl, are sometimes used. But cocaine and a somewhat similar substance, eucaine, have of late been more extensively used on man, after their harmlessness had been first shown by experiments on animals. In 1885 Corning, of New York, injected a solution of cocaine as near to the spinal cord as was possible, and produced insensibility of all the body below the point of injection by the effect of the cocaine upon the spinal cord. A few years ago Quincke, of Kiel, in Germany, devised a means of puncturing the spinal canal itself in the lumbar region (the lowest part of the small of the back) for the purpose of drawing off some of the fluid for examination."}]}
{"messages": [{"role": "assistant", "content": "A few years ago Quincke, of Kiel, in Germany, devised a means of puncturing the spinal canal itself in the lumbar region (the lowest part of the small of the back) for the purpose of drawing off some of the fluid for examination. This suggested to Bier, then of Kiel, who was apparently ignorant of Corning’s work, that cocaine could be injected through a hollow needle inserted into the spinal canal by “lumbar puncture” and so produce anæsthesia of all the body below this point. This method was published by him in 1899, and was soon repeated in America. In France, however, it has been practised more than elsewhere, Tupper, of Paris, having successfully done over two hundred operations by “spinal anæsthesia.” All of the body below the diaphragm can thus be deprived of sensibility. The method will probably never replace ether and chloroform, but in many cases is a valuable aid to the surgeon. But it has its dangers and its inconveniences."}]}
{"messages": [{"role": "assistant", "content": "But it has its dangers and its inconveniences. The ideal anæsthetic is not that which destroys sensibility and yet leaves the patient perfectly conscious, as spinal anæsthesia does. A patient to whom I recently proposed it for certain special reasons rejected it, saying, with probable truth, that she could never bear the strain of lying on the table perfectly conscious of all that was being done and frightened by any surgical emergency which might easily arise in such a long, difficult, and dangerous operation. The ideal anæsthetic is that which will abolish pain and consciousness without danger to life. The twentieth century will undoubtedly see the discovery of this safe and efficient anæsthetic. ANTISEPSIS \nBut the limits of surgical progress were not yet reached."}]}
{"messages": [{"role": "assistant", "content": "ANTISEPSIS \nBut the limits of surgical progress were not yet reached. Let me quote again from the address before alluded to: \n    “Even the introduction of anæsthesia, however, did not rid     surgery of all its terrors. The acute pain of the operation was     abolished, but the after-suffering, as I know only too well,     in my early surgical days, was something dreadful to see. The     parched lips of the poor sufferer, tossing uneasily during     sleepless nights; wounds reeking with pus, and patients dying by     scores from blood-poisoning, from erysipelas, from tetanus, from     gangrene, were only too familiar sights in the pre-antiseptic     days. Then, again, there arose one of these deliverers of the     human race whose name can never be forgotten and whose fame will     last so long as time shall endure. Jenner, Warren, and Lister     are a triumvirate of names of which any profession may well be     proud."}]}
{"messages": [{"role": "assistant", "content": "Jenner, Warren, and Lister     are a triumvirate of names of which any profession may well be     proud. Thank God, they all sprang from virile Anglo-Saxon loins! No praise, no reward, no fame is too great for them. That Lord     Lister still lives to see the triumph of his marvellous services     to humanity is a joy to all of us. And when the profession arose     _en masse_, within the last few years, at the International     Congress of Berlin, and at the meeting of the British Medical     Association in Montreal, and welcomed him with cheer after cheer,     it was but a feeble expression of gratitude for benefits which no     words can express. “Before Lister’s day erysipelas, tetanus, gangrene, and     blood-poisoning in its various phases were the constant     attendant of every surgeon."}]}
{"messages": [{"role": "assistant", "content": "“Before Lister’s day erysipelas, tetanus, gangrene, and     blood-poisoning in its various phases were the constant     attendant of every surgeon. They were dreaded guests at almost     any operation; and when in rare cases we obtained primary union     without a drop of pus, without fever, and with but little     suffering, it was a marvellous achievement. Now it is precisely     reversed. The surgeon who does not get primary union without     a drop of pus, with no fever, and with little suffering, asks     himself—what was the fault in my technic? To open the head, the     abdomen, or the chest thirty years ago was almost equivalent to     signing the death-warrant of a patient. The early mortality of     ovariotomy was about sixty per cent.; two out of three died."}]}
{"messages": [{"role": "assistant", "content": "The early mortality of     ovariotomy was about sixty per cent.; two out of three died. Now     many a surgeon can point to a series of one hundred abdominal     operations with a fatality of only two or three per cent. When     Sir Spencer Wells recorded his first one thousand cases of     ovariotomy it was calculated that after deducting the years which     the patients who died from the operation would have lived had no     operation been done the net result of the thousand cases was an     addition of twenty thousand years to human life. One thousand     ovariotomies under antiseptic precautions at the present would     certainly add at least thirty thousand years to human life. Would     not such a guerdon be enough for any man? “This, too, is a direct result of laborious laboratory     researches, beginning with the investigations of Liebig and     Pasteur on fermentation."}]}
{"messages": [{"role": "assistant", "content": "“This, too, is a direct result of laborious laboratory     researches, beginning with the investigations of Liebig and     Pasteur on fermentation. Lister went still further. Even before     the discovery of the bacteria of suppuration, of tetanus, and     of erysipelas he showed us experimentally how, by surgical     cleanliness, we could avoid all infection and so banish these     pests from our hospitals and bring life and health to many who     otherwise would have perished from operations which are now     perfectly safe. “The mortality of compound fractures in the pre-antiseptic days     was about sixty per cent. It was one of the most dreaded of     all accidents. Its mortality now is perhaps not over three per     cent., and the mortality from sepsis after such a fracture, in     the hands of well-instructed surgeons, is almost nil."}]}
{"messages": [{"role": "assistant", "content": "Its mortality now is perhaps not over three per     cent., and the mortality from sepsis after such a fracture, in     the hands of well-instructed surgeons, is almost nil. Prior to     Lister’s day the mortality of major amputations varied from fifty     to sixty-three per cent. Now it is from ten to twenty per cent. And so I might go on with operation after operation and show how     they have become so safe that one need not dread any, saving     exceptional cases. “These two modern discoveries, anæsthesia and antisepsis, have     utterly revolutionized modern surgery. They have made possible     operations which, by reason of their length and pain and danger,     were utterly unjustifiable in former days, but are now the daily     occupation of a busy surgeon."}]}
{"messages": [{"role": "assistant", "content": "They have made possible     operations which, by reason of their length and pain and danger,     were utterly unjustifiable in former days, but are now the daily     occupation of a busy surgeon. And, far better than this, they     have enabled us to bring to homes and hearts, which otherwise     would have been broken up and wrung with sorrow, the comfort of     life restored to dear ones upon whom depended the happiness and     support of the families. Translate figures into happy hearts and     prosperous homes if you can, and then you can tell me what Warren     and Lister have done for humanity!” \nThe result of these two wonderful discoveries has been to separate us from the surgical past, as by a great gulf. “Great theologians, such as a Calvin or a Jonathan Edwards,     were they recalled to life, could discourse as learnedly as     ever of predestination and free will; great preachers, as     a Beecher or a Spurgeon, could stir our souls and warm our     hearts as of old; great jurists, as a Justinian or a Marshall,     could expound the same principles of law which hold good for     all time; great forensic orators, as a Burke or a Webster,     could convince us by the same arguments and arouse us by the     same invectives or the same eloquence that made our fathers     willing captives to their silver tongues. But to-day, so rapid     has been our surgical progress, a Velpeau, a Sir William     Ferguson, or a Pancoast, all of whom have died within the     last thirty years, could not teach modern surgical principles     nor perform a modern surgical operation. Even our every-day     surgical vocabulary—staphylococcus, streptococcus, infection,     immunity, antisepsis and asepsis, toxin and antitoxin—would be     unintelligible jargon to him; and our modern operations on the     brain, the chest, the abdomen, and the pelvis would make him     wonder whether we had not lost our senses, until, seeing the     almost uniform and almost painless recoveries, he would thank God     for the magnificent progress of the last half-century, which had     vouchsafed such magical, nay, such almost divine, power to the     modern surgeon.” \n\nTHE SURGERY OF WAR \nOne of the immediate consequences of the introduction of the antiseptic method has been a remarkable mitigation of the horrors of war."}]}
{"messages": [{"role": "assistant", "content": "Even our every-day     surgical vocabulary—staphylococcus, streptococcus, infection,     immunity, antisepsis and asepsis, toxin and antitoxin—would be     unintelligible jargon to him; and our modern operations on the     brain, the chest, the abdomen, and the pelvis would make him     wonder whether we had not lost our senses, until, seeing the     almost uniform and almost painless recoveries, he would thank God     for the magnificent progress of the last half-century, which had     vouchsafed such magical, nay, such almost divine, power to the     modern surgeon.” \n\nTHE SURGERY OF WAR \nOne of the immediate consequences of the introduction of the antiseptic method has been a remarkable mitigation of the horrors of war. Our recent war with Spain has proved, and the present military operations in the Philippines and of the British in South Africa will still further prove, its advantages. Witness a little book written by Professor von Esmarch, of Kiel, Germany, with the apt title, _The Fight of Humanity Against the Horrors of War_; with an appendix, entitled, “The Samaritan on the Battle-field.” One of the most valuable means for the preservation of human life is carried by every soldier in a modern civilized army as a part of his regulation outfit, a “First Aid Package” for the treatment of any wound or injury; and one of the most valuable and interesting papers read before the American Surgical Association, at its meeting in Chicago in 1899, was by Professor Senn on the “First Aid Package.” This first aid package contains an antiseptic dressing, which can be applied to all but the gravest wounds for the purpose of preventing infection, which is the principal danger to life after accident or injury. The universal testimony of our surgeons in Cuba was that by its use most wounds were prevented from becoming infected, and, therefore, inflamed, and that the number of operations was greatly diminished by reason of its use. BACTERIOLOGY \nIn experimental science, two methods of progress are observed; first, in actual practice certain methods are adopted because they are found to be the most advantageous and useful, though we cannot explain why it is so—_i.e._, practice outstrips theory. Again, as a result of experimental investigation, certain facts are discovered which explain why the practical methods just alluded to are the best, and this in turn suggests further improvements in our practice—_i.e._, theory outstrips practice and enlarges its domain."}]}
{"messages": [{"role": "assistant", "content": "Again, as a result of experimental investigation, certain facts are discovered which explain why the practical methods just alluded to are the best, and this in turn suggests further improvements in our practice—_i.e._, theory outstrips practice and enlarges its domain. Thus outstripping theory, the practical advance made by Lister was an example of the first. His striking results in turn stimulated scientific observers to make new discoveries of the greatest importance, and thus science immensely improved and widened our practical methods. No definite year or day can be assigned as the birth-date of Lord Lister’s antiseptic methods, as we can, for instance, for vaccination or for anæsthesia. We may assume, at least for this country, the summer of 1876 as the starting-point. During that year Lord Lister attended the International Medical Congress held in Philadelphia, and demonstrated his then methods and convinced a few surgeons of their immense advantages."}]}
{"messages": [{"role": "assistant", "content": "During that year Lord Lister attended the International Medical Congress held in Philadelphia, and demonstrated his then methods and convinced a few surgeons of their immense advantages. Even before that date there had been very many experiments and observations, especially on the blood. In 1863 Davaine, in France, had discovered little rod-like bodies in the blood in wool-sorters’ disease, or anthrax, which he named from their shape “bacteria,” or “little rods.” This name has been adopted for all forms of germs, though many of them are not rod-like in their shape. Not until 1881 was the cause of inflammation and suppuration (the formation of pus or “matter”) discovered. In that year Ogston, of Aberdeen, published experiments which he believed demonstrated the fact that certain bacteria were the cause of suppuration. Since then this has been amply confirmed not only by experiments upon animals, but by observation in man."}]}
{"messages": [{"role": "assistant", "content": "Since then this has been amply confirmed not only by experiments upon animals, but by observation in man. In 1882 Robert Koch, of Berlin, discovered the cause of tuberculosis, a little rod-like body, which is named the “bacillus” of tuberculosis. In 1883 Fehleisen discovered the germ of erysipelas, and in 1887 Nicolaier and Rosenbaum discovered the bacillus of tetanus or lockjaw. So recent have been the discoveries in bacteriology which have led to vast improvements in our methods of treatment of wounds and the performance of operations. While the principles established by Lord Lister have remained unchanged, the details in the treatment have been greatly simplified and made more efficient. For the information of the general reader, let me state a few facts."}]}
{"messages": [{"role": "assistant", "content": "For the information of the general reader, let me state a few facts. Bacteria are divided into two principal classes, in accordance with their form. One, known as “cocci,” from the Greek word coccus—“berry”—may be likened to billiard-balls. Some of these occur in bunches, which have been likened to bunches of grapes, and hence are called, again from a Greek term, “staphylococci.” Others are arranged in chains, like beads, and are called “streptococci.” These last are very much more virulent and dangerous than the staphylococci. Both of these produce pus or matter, and they are the most widely diffused and most common forms found in infected or suppurating wounds. One form is the cause of erysipelas."}]}
{"messages": [{"role": "assistant", "content": "One form is the cause of erysipelas. A second form, known as “bacilli,” may be likened to a lead-pencil. Among the various bacilli that have been discovered are those of tuberculosis, glanders, tetanus or lockjaw, etc. I omit many others found in medical disorders, as they do not concern this paper. How important these discoveries are may be seen by the following facts: Tuberculosis, next to that of suppuration, is, perhaps, the most widely extended infection to which man, as well as animals, is liable. We are all familiar with it in the form of “consumption,” but the non-medical reader is, perhaps, not aware of the fact that it affects not only the lungs, but also the bowels in consumption of the bowels; the bones, as is seen by every surgeon almost daily, and especially as the cause of the crooked backs seen in spine diseases; in the joints, as is seen in hip-joint disease, white swelling of the knee, ankle-joint disease, and similar disease of all the other large joints of the body; in the brain, in tubercular meningitis; in the abdominal cavity, in tubercular peritonitis; in the skin, in certain forms of ulceration, commonly called lupus; in the glands, as in the swollen glands, or “bunches,” in the neck, and endless other varieties which I need not name."}]}
{"messages": [{"role": "assistant", "content": "We are all familiar with it in the form of “consumption,” but the non-medical reader is, perhaps, not aware of the fact that it affects not only the lungs, but also the bowels in consumption of the bowels; the bones, as is seen by every surgeon almost daily, and especially as the cause of the crooked backs seen in spine diseases; in the joints, as is seen in hip-joint disease, white swelling of the knee, ankle-joint disease, and similar disease of all the other large joints of the body; in the brain, in tubercular meningitis; in the abdominal cavity, in tubercular peritonitis; in the skin, in certain forms of ulceration, commonly called lupus; in the glands, as in the swollen glands, or “bunches,” in the neck, and endless other varieties which I need not name. The bacillus of lockjaw is found in great abundance around stables, and this explains the fact that hostlers, drivers, cavalrymen, all of whom had to do with horses, are especially liable to attacks of lockjaw. Moreover, certain bacteria thrive best when exposed to the open air. Other bacteria, and among them the bacilli of lockjaw, thrive best when the air is excluded, and this explains the danger of treading on a rusty nail, which is popularly and rightly known as peculiarly liable to produce lockjaw. The reason is not because it is a nail, nor because it is old, nor because it is rusty, but because from the earth in which it lies it is most apt to be the means of introducing into a punctured wound the bacilli of lockjaw. Such a wound bleeds but very little, the blood soon crusts and excludes the air, and if any of the bacilli of lockjaw have been carried into the body, they find in such a closed wound, from which the air is excluded, the most favorable conditions for growth and infection of the whole body."}]}
{"messages": [{"role": "assistant", "content": "Such a wound bleeds but very little, the blood soon crusts and excludes the air, and if any of the bacilli of lockjaw have been carried into the body, they find in such a closed wound, from which the air is excluded, the most favorable conditions for growth and infection of the whole body. Knowing these facts from experiment, the treatment is clear. Lay open such a wound and disinfect it. These two forms, the “cocci,” or berry-like bacteria, and the “bacilli,” or rod-like bacteria, comprise the great majority of dangerous bacteria. It must be remembered that there is an enormous number of bacteria which are not dangerous; some of them are entirely harmless even if introduced into the human body. Others are the bacteria of decomposition, or putrefaction, which are known as “saprophytic” bacteria."}]}
{"messages": [{"role": "assistant", "content": "Others are the bacteria of decomposition, or putrefaction, which are known as “saprophytic” bacteria. All of the harmless ones are known as “non-pathogenic,” that is, non-producers of disease. Those which produce disease are known as “pathogenic,” and those which produce suppuration as “pyogenic” or pus-producing bacteria. All of these bacteria are plants, and not, as is very frequently supposed, animals of a low form. The danger from their introduction into the body can be best appreciated, perhaps, by the statement of Belfield, who estimated that a single bacterium which weighs, approximately, only the 1-40,000,000 part of a grain, if given plenty of food and plenty of “elbow room,” would so rapidly develop that in three days it would form a mass weighing 800 tons! It is the old story of the blacksmith who was to get a penny for the first nail, two for the second, four for the third, and so on till a set of shoes would cost more than Crœsus could pay for."}]}
{"messages": [{"role": "assistant", "content": "It is the old story of the blacksmith who was to get a penny for the first nail, two for the second, four for the third, and so on till a set of shoes would cost more than Crœsus could pay for. The effect of the bacteria has been determined by experiment to be proportionate to the dose. A cubic centimetre is a cube two-fifths of an inch on each side. One-tenth of such a cube of pure culture of one bacterium (_Proteus vulgaris_) contains 225,000,000 bacteria, and if injected under the skin of a rabbit will produce death. Less than 18,000,000 will produce no effect whatever. Of one kind of staphylococcus, if 250,000,000 are introduced under the skin of a rabbit there will be produced a small abscess, but it requires 1,000,000,000 to produce speedy death."}]}
{"messages": [{"role": "assistant", "content": "Of one kind of staphylococcus, if 250,000,000 are introduced under the skin of a rabbit there will be produced a small abscess, but it requires 1,000,000,000 to produce speedy death. On the other hand, of the bacillus of lockjaw it requires only 1000 to produce death, so virulent is this germ. Moreover, their effect on tissues and persons in different states varies very much. Thus, it is found that when a certain number of bacteria are injected into the cavity of the abdomen of an animal, if the animal is healthy and the peritoneum (the thin lining membrane of the abdomen) is healthy, the animal will recover perfectly well; but if the peritoneum be scraped and torn (and it must be remembered that the healthy peritoneum is devoid of sensation), that the same dose which before was harmless will now produce a violent peritonitis and very likely death. The practical lesson from this experiment upon animals is very evident. Every surgeon who opens the abdomen is most careful, if possible, not to injure the peritoneum, but manipulates with the greatest care lest fatal results follow any serious injury to that membrane."}]}
{"messages": [{"role": "assistant", "content": "Every surgeon who opens the abdomen is most careful, if possible, not to injure the peritoneum, but manipulates with the greatest care lest fatal results follow any serious injury to that membrane. So, too, if the general health be impaired, it is found that an injection from which a healthy animal would recover will be followed by fatal consequences if the general health is below par. Again, if an animal has a simple fracture of his thigh-bone, and that is the only injury that he receives, no infection from the exterior having occurred, he will make a good recovery; but if at the same time he receives a lacerated wound, it may be even in another part of the body, and this wound, not being cared for most scrupulously, becomes infected, the infection will fasten on the distant spot of least resistance, the broken thigh-bone, and will produce a most dangerous and very frequently fatal form of inflammation. I need scarcely point out in this connection, as in fact throughout this entire consideration of bacteriology, how important a part in its development has been played by experiment upon animals. The experimental facts just stated are of vital importance in the treatment of surgical diseases, and evidently could not have been determined upon mankind. It is not too much to say that had vivisection been restricted or prohibited the surgery of to-day would be the barbarous surgery of thirty years ago."}]}
{"messages": [{"role": "assistant", "content": "It is not too much to say that had vivisection been restricted or prohibited the surgery of to-day would be the barbarous surgery of thirty years ago. Even granting that an enormous number of the bacteria are harmless, the wonder is that with so many foes on every hand we live an ordinary lifetime. Fortunately, however, in the human body there is not only a lack of food sufficient and “elbow room” enough for them to work their dire effects, but there is that which “makes for righteousness” in our physical organization as well as in our souls. The moment that bacteria are introduced into the human body a certain number of cells hasten to destroy them. These are called “phagocytes” or devouring cells, because they eat up the bacteria. Whether the patient survives or dies depends on whether the bacteria get the upper hand of the phagocytes or the phagocytes the upper hand of the bacteria."}]}
{"messages": [{"role": "assistant", "content": "Whether the patient survives or dies depends on whether the bacteria get the upper hand of the phagocytes or the phagocytes the upper hand of the bacteria. These statements are very easy to make, but the results have only been obtained by prolonged and laborious investigations in the laboratory and by experiments upon animals which have demonstrated these facts. The bacteria are recognized by various methods: First, by form. Many which are identical in appearance, however, differ greatly in effects. A handful of turnip-seed and a handful of rape-seed look very much alike, but if they are planted the plants differ so greatly that we can recognize the difference in the seed by the difference in the crop; hence the second method of recognizing differences in bacteria is by planting them. Different methods have been practised."}]}
{"messages": [{"role": "assistant", "content": "Different methods have been practised. Some are sown on the raw surface of a potato; others on bread paste; others in certain jelly-like materials, such as gelatine or agar-agar. It was soon found as a result of these experiments that the bacteria flourished best, some in one soil, some in another. Again, the crops of mould which come from them differ greatly in color, some being black, some red, some white, some yellow, etc. A third method also is by staining them with various dyes, when it is found that some bacteria will take one stain best, others will take another, and so on through the whole list. At first it was thought that these bacteria existed chiefly in the air, and hence in Lister’s early methods powerful spray-producing apparatus were used; but while it is true that they do exist in the air, it is found that this is not the principal source of infection."}]}
{"messages": [{"role": "assistant", "content": "At first it was thought that these bacteria existed chiefly in the air, and hence in Lister’s early methods powerful spray-producing apparatus were used; but while it is true that they do exist in the air, it is found that this is not the principal source of infection. There is no substance (which has not been disinfected) that is not covered with the germs of these little plants. They exist in our food and drink; but the intestine is, one may say, a natural home in which many exist without harm to the body. For surgical purposes their existence is most important, first, in the earth, where, as I have already shown, the bacillus of lockjaw is most frequently found. So, too, the bacillus of wool-sorters’ disease (_Anthrax_) exists in the earth. If an animal dying of anthrax is buried, worms coming from the carcass up through the ground carry the infection, so that other animals grazing over this surface will become readily infected."}]}
{"messages": [{"role": "assistant", "content": "If an animal dying of anthrax is buried, worms coming from the carcass up through the ground carry the infection, so that other animals grazing over this surface will become readily infected. The means by which we can avoid infection from the earth is very evident, viz., every person who has been run over by the cars or who has fallen on the ground and broken his leg, etc., must have the wound most carefully cleansed from all dirt. If this is scrupulously done the danger of tetanus or other similar earth-born bacterial disease is almost nothing. A still greater danger to every patient, however, is found in the clothing, in the skin, and all dressings which are applied to wounds. The skin is full of bacteria of the most dangerous kind; even the spotless hands of the bride, in the eyes of the surgeon, are dirty. No one can touch a wound with ordinarily clean hands without infecting it."}]}
{"messages": [{"role": "assistant", "content": "No one can touch a wound with ordinarily clean hands without infecting it. All clothing, dressings—_e.g._, lint and soft linen rags, and such like—are full of bacteria of the most dangerous kind. Perhaps the most dangerous place is the space under the nails of the surgeon’s hand, for the mere mechanical removal of any dirt under the nails by cleansing them does not make them clean surgically. The nails must be cut short and prepared in a way I shall mention directly, or they are full of peril to any patient into whose wound a non-disinfected finger is introduced. Again, another source of infection which thirty years ago we never thought of is our instruments. Then instruments were washed with soap and water and were made clean to the eye, but they were still covered with invisible death-dealing bacteria which hid especially in the joints and irregularities of the surface of all instruments."}]}
{"messages": [{"role": "assistant", "content": "Then instruments were washed with soap and water and were made clean to the eye, but they were still covered with invisible death-dealing bacteria which hid especially in the joints and irregularities of the surface of all instruments. All of these somewhat detailed statements lead up to a consideration of the difference between the old surgery and the new. Thirty years ago when an operation was to be performed or an accident cared for we laid out our instruments which were visibly clean, used them with hands which were as clean as those of any gentleman, and applied soft linen rags, lint, and other dressings. To-day we know that these apparently clean instruments, hands, and dressings are covered with bacteria, which produce infection, and, therefore, suppuration, and frequently run riot in blood-poisoning, erysipelas, lockjaw, and death. How does a modern surgeon perform an operation? All bacteria can be killed by heat."}]}
{"messages": [{"role": "assistant", "content": "All bacteria can be killed by heat. Cold has no effect upon them, but the temperature of boiling water (212° Fahr.) is sufficient to destroy them all usually within fifteen or twenty minutes; hence, first, instruments are all boiled; and, secondly, dressings are either steeped in such solutions as have been found to destroy the bacteria, such as carbolic acid or corrosive sublimate, or other preparations, or, still better, are placed in sterilizers, that is to say, metal cylinders, which are then filled with steam, usually under pressure, so as to obtain a temperature of 240° Fahr., and thus make sure of the death of the bacteria. Unfortunately, our hands cannot be boiled or steamed, but the modern surgeon first uses soap and water most vigorously over his hands and arms up to the elbow. The nails are cut short and the scrubbing-brush is especially applied to the nails so as to clean the fingers at the ends. Then by various means, such as pure alcohol, which is one of our best disinfectants, or solutions of corrosive sublimate, and other means too technical to mention, the hands are sterilized. Rubber gloves are frequently used, so as to preclude infection, as they can be steamed to 240° Fahr."}]}
{"messages": [{"role": "assistant", "content": "Rubber gloves are frequently used, so as to preclude infection, as they can be steamed to 240° Fahr. Removing at least his outer clothing, the surgeon puts on a cotton gown which has been steamed and so made free from bacteria. Not a few surgeons also wear sterilized caps, so that any bacteria in the hair will not be sifted into a wound, and some wear respirators of sterile gauze over the mouth and beard for the same reason. All the dressings have been sterilized by superheated steam. All the threads by which blood-vessels are tied have been either boiled or otherwise sterilized. All the material for sewing up the wounds, and the needles with which they are sewn, have been similarly disinfected."}]}
{"messages": [{"role": "assistant", "content": "All the material for sewing up the wounds, and the needles with which they are sewn, have been similarly disinfected. The skin of the patient is also sterilized, usually the day beforehand, in the same manner in which the surgeon’s hands have been disinfected, and are disinfected a second time just at the moment of the operation. If the case is one of accident, such as a crushed leg from a trolley-car, all of the dirt is most carefully washed away with soap and water, and the parts are disinfected, not only on the exterior, but also by prolonged washing with some cleansing agent in the interior of the wound, the patient being under the influence of ether, of course. It is easily seen from such a description of a modern operation that no case can receive due care in one of our modern homes, even the best. The facilities do not exist, and hence surgeons are more and more declining to do operations, whether for accident or disease, in private houses, except in a case of absolute necessity, and a happy custom is growing more and more in favor with the community of having all operations and all accidents cared for in a well-equipped hospital. RESULTS OF MODERN SURGERY \nAs the result of our ability to perform operations without pain, thanks to anæsthesia, and our ability to perform operations without infection, and, therefore, almost without danger, thanks to antisepsis, the range of modern surgery has been enormously increased."}]}
{"messages": [{"role": "assistant", "content": "RESULTS OF MODERN SURGERY \nAs the result of our ability to perform operations without pain, thanks to anæsthesia, and our ability to perform operations without infection, and, therefore, almost without danger, thanks to antisepsis, the range of modern surgery has been enormously increased. Unless one has lived through the old surgery and into the new he scarcely can appreciate this widening of the field of operative surgery. Thirty years ago, in consequence of the great danger of opening the head, the chest, or the abdomen, or, in fact, of making an incision anywhere about the body, the surgeon never dared to interfere until he was obliged to do so. Hence, not only were many modern operations not even thought of, but in obscure cases we had to wait until time and disease developed symptoms and physical signs such that we were sure of our diagnosis, and then, knowing that death would follow if we did not interfere, we ventured to operate. Now we anticipate such a fatal termination, and in most cases can avert it. In perhaps no class of cases has the benefit of this immunity from infection and danger been shown than in the obscure diseases of the brain and the abdomen."}]}
{"messages": [{"role": "assistant", "content": "In perhaps no class of cases has the benefit of this immunity from infection and danger been shown than in the obscure diseases of the brain and the abdomen. To-day, if we are uncertain as to whether there is serious danger going on which, if unchecked, will result in death, we deliberately open the one cavity or the other, in order to find out the exact state of affairs. Supposing that the mischief is trifling, or even that there is no mischief, we then know how to deal with the symptoms which have been puzzling us. So far as the exploratory operation is concerned, the patient recovers from it in a short time, and, meantime, perhaps has also been cured of the symptoms which were before so ill understood. If any serious disease is found, in the majority of cases we can cope with it successfully. Before the days of antisepsis and anæsthesia the field of operation was greatly restricted, and practically the removal of tumors, amputations, and a few other operations were all that were done."}]}
{"messages": [{"role": "assistant", "content": "Before the days of antisepsis and anæsthesia the field of operation was greatly restricted, and practically the removal of tumors, amputations, and a few other operations were all that were done. Now all the then inaccessible organs are attacked with an intrepidity born of an assurance of safety. Recovery usually sets the seal of approval on the judgment of the surgeon. Thirty years ago, taking all operations together, fully one-third of our patients died, many of them often from slight operations which were followed by infection. To-day, including even the far more grave operations which are now done, the general mortality will scarcely exceed five per cent., and many surgeons are able, in a series of several hundred operations, to save ninety-seven out of every hundred patients! SERUM TREATMENT \nAnother remarkable recent discovery, the result of numerous and careful investigations in the laboratory, is a wholly new means of treatment, viz., that method which is known as orrhotherapy, or serumtherapy, or the treatment by injecting certain antitoxins under the skin by a hypodermatic syringe."}]}
{"messages": [{"role": "assistant", "content": "SERUM TREATMENT \nAnother remarkable recent discovery, the result of numerous and careful investigations in the laboratory, is a wholly new means of treatment, viz., that method which is known as orrhotherapy, or serumtherapy, or the treatment by injecting certain antitoxins under the skin by a hypodermatic syringe. It would lead me too far to enter into the theory upon which these were first used. Suffice it to say that in the blood of an animal that has passed through a certain disorder the liquid part of the blood contains an antidote or antitoxin. If a certain amount of this is injected under the skin of an animal or man suffering from the same disorder in its incipient stages, the antitoxin prevents the development of the disease. The use of this method has thus far been much more medical than surgical, and its results in diphtheria and other medical disorders have been perfectly marvellous. In surgery, however, less favorable results have been obtained, but in all probability in the future we shall be able to do for some of our surgical disorders what the physician can do to-day for diphtheria."}]}
{"messages": [{"role": "assistant", "content": "In surgery, however, less favorable results have been obtained, but in all probability in the future we shall be able to do for some of our surgical disorders what the physician can do to-day for diphtheria. [For the results in diphtheria, see Professor Osler’s paper.] \nThere has also been discovered another means which in surgery has rendered some valuable service. From certain organs, as, for instance, the thyroid gland (the gland whose enlargement produces goitre), we can obtain a very potent extract of great value. In cases of goitre very noteworthy results have already been obtained by the administration of the thyroid extract. A number of other organs in the body of animals have been used to combat certain disorders in the human body with advantage. The chief development of both of these new forms of medication, however, will take place in the twentieth century."}]}
{"messages": [{"role": "assistant", "content": "The chief development of both of these new forms of medication, however, will take place in the twentieth century. INSTRUMENTS OF PRECISION \nAnother direction in which the century has seen enormous progress is in the introduction of instruments of precision. When I was a student in the early 60’s, instruction in microscopy was conspicuous only by its absence from our medical curriculum. Now every student who graduates is more or less of an accomplished microscopist, and carries into his practice the methods and observations which the microscope furnishes. At the same period I remember being greatly interested in a discussion which two of my teachers had as to whether it was possible to make an application accurately to the vocal chords in the larynx. Now every tyro in medicine makes such applications to the larynx as a routine procedure in cases requiring it, and similar methods have been applied by the ophthalmoscope to examine the interior of the eye; the rhinoscope, to examine the interior of the nose; the otoscope, for examination of the ear; and other similar instruments for examining all the other hollow organs in the body."}]}
{"messages": [{"role": "assistant", "content": "Now every tyro in medicine makes such applications to the larynx as a routine procedure in cases requiring it, and similar methods have been applied by the ophthalmoscope to examine the interior of the eye; the rhinoscope, to examine the interior of the nose; the otoscope, for examination of the ear; and other similar instruments for examining all the other hollow organs in the body. If I add to these the hypodermatic syringe; the aspirator, which may be described as a large hypodermatic syringe for suction instead of injection; the clinical thermometer, which was introduced in the late 60’s; the hemostatic forceps, for controlling hemorrhage by seizing the blood-vessels and clamping them till we have time to tie them; and other instruments intended to facilitate our operative methods, it will be seen at once that the armamentarium of the modern surgeon is very different from that of his predecessor at the beginning, or even at the middle, of the century. THE RÖNTGEN RAY \nOne of those extraordinary discoveries which startle the whole world came nearly at the end of the nineteenth century, in the winter of 1895–96. At that time a modest professor in the University of Würzburg announced that he could readily see the skeleton inside the body through the flesh! Naturally, the first announcement was received with almost absolute incredulity; but very soon his discovery was confirmed from all sides, and it has now taken its place among the recognized phenomena of science. By means of certain rays, which, being of unknown nature, were called “X”-rays, after the well-known mathematical X, or unknown quantity, Professor Röntgen has shown us that not only can the bones be seen, but that almost every substance in the body can be seen and reproduced in pictures."}]}
{"messages": [{"role": "assistant", "content": "By means of certain rays, which, being of unknown nature, were called “X”-rays, after the well-known mathematical X, or unknown quantity, Professor Röntgen has shown us that not only can the bones be seen, but that almost every substance in the body can be seen and reproduced in pictures. The reason for this is because they are all obstacles to the passage of these X-rays and so produce shadows on a sensitized photographic plate. If the exposure is sufficiently prolonged the rays penetrate even through the bones and act upon the photographic plate, so that no shadow remains. If the rays are allowed to penetrate for a shorter time the bones show dense shadows, and one can get a light shadow of the soft parts. If the exposure is still shorter, then we can recognize the dense shadow of the bone, the much less dense shadows of the muscles, and the still lighter shadows of the layer of fat immediately under the skin. The heart can be seen beating, and its shadow is now a well-recognized feature in skiagraphs of the chest."}]}
{"messages": [{"role": "assistant", "content": "The heart can be seen beating, and its shadow is now a well-recognized feature in skiagraphs of the chest. At first it was thought impossible to discover anything inside the bony skull, but there are now on record nearly a score of instances in which bullets have been detected within the skull, and after trephining have been found and removed exactly at the location indicated. It is a very common thing now to locate a piece of steel or other similar foreign bodies within the eyeball by the method of Dr. Sweet, or some similar method, within one or two millimetres (a millimetre is one-twenty-fifth of an inch). It is now well recognized that even stones in the kidney will throw shadows sufficiently strong for them to be recognized, and by noting their level in relation to the vertebræ we can tell precisely in what part of the kidney to make the incision in order to find and remove them. It has happened to myself and many other surgeons in the past to cut down upon a kidney, believing that there was a stone in the kidney, only to find that we had been misled by the apparently clear symptoms of such a foreign body."}]}
{"messages": [{"role": "assistant", "content": "It has happened to myself and many other surgeons in the past to cut down upon a kidney, believing that there was a stone in the kidney, only to find that we had been misled by the apparently clear symptoms of such a foreign body. In future no such mistake should be made by any surgeon within reach of a skilful skiagrapher. Unfortunately, gall stones and numerous other foreign bodies, vegetable substances such as beans, corn, wood, etc., being as transparent to the X-rays as are the soft parts, are not revealed by means of this new method of investigation; but cavities in the lung, abscesses in bone, and similar diseases which produce thinning of the lung, bone, and other such organs, and so lighten instead of deepen the shadows, can now be recognized by means of light spots in the pictures as well as others by means of a shadow. I spoke a moment ago of the need of a “skilful” skiagrapher, for it must be remembered that there may be the same difference in the personal skill, and, therefore, in the reliability of the results in skiagraphy as there is in photography. A poor photographer will get very different results from a skilful one, even if he uses precisely the same quality of plates and precisely the same camera. Personal skill and experience in the skiagrapher is, therefore, one of the most important elements in success."}]}
{"messages": [{"role": "assistant", "content": "Personal skill and experience in the skiagrapher is, therefore, one of the most important elements in success. It must be remembered also that the X-rays in not a few cases may mislead us. I have, personally, fractured a bone on account of deformity, taken an X-ray picture immediately after the operation, the picture showing not the slightest evidence of a fracture, which I absolutely knew existed. Moreover, foreign bodies found on the outside of the person may mislead us, as, for example, the metal part of suspenders, a coin in one’s pocket, and such like. They look in the picture as if they were inside rather than outside the body, and any article the shape or size of which would not reveal its nature might easily be mistaken for a foreign body within the patient. Therefore, in many cases only an expert can determine precisely what the skiagraph means."}]}
{"messages": [{"role": "assistant", "content": "Therefore, in many cases only an expert can determine precisely what the skiagraph means. I especially mention this, because there is a tendency at present to utilize skiagraphs in court in order to convince the jury that such a picture is an evidence of malpractice. Such pictures always need an interpreter in order to judge correctly of their meaning. It is precisely as if the jury were asked to look through a microscope. I have been myself accustomed to use the microscope for thirty years, but there are many instances even yet in which I am obliged to ask a pathologist or bacteriologist what I really am looking at in the microscope. While one may make a mistake of small moment in some cases, yet if a man’s life or liberty or purse is at the mercy of a jury which does not know how to interpret a skiagraph, and, may, therefore, give a verdict which is “precisely wrong,” as Professor Lincoln, my old teacher of Latin, used to call many of our translations, it will be a very serious matter and lead to gross injustice."}]}
{"messages": [{"role": "assistant", "content": "While one may make a mistake of small moment in some cases, yet if a man’s life or liberty or purse is at the mercy of a jury which does not know how to interpret a skiagraph, and, may, therefore, give a verdict which is “precisely wrong,” as Professor Lincoln, my old teacher of Latin, used to call many of our translations, it will be a very serious matter and lead to gross injustice. CITY AND VILLAGE HOSPITALS \nAnother great improvement in our means of caring for our surgical patients is the establishment of hospitals all over the land. These, happily, are not limited to our great cities, but in every country town and not a few large villages small but well-equipped and well-managed hospitals have been established which have done incalculable good. It is not too much to say that every city or town establishing such a hospital is repaid a hundredfold. TRAINED NURSES \nThe trained nurse has fortunately come to stay. In fact, our antiseptic methods as above described have made the trained nurse indispensable."}]}
{"messages": [{"role": "assistant", "content": "In fact, our antiseptic methods as above described have made the trained nurse indispensable. The old nurse, who, by many clumsy experiments on her patients, had obtained a certain rule-of-thumb knowledge of the care of the sick, can no longer assist in a surgical operation or properly care for any surgical patient. The modern nurse must of necessity be a well-educated, well-trained woman, knowing thoroughly modern antiseptic methods, and on the alert to observe every symptom of improvement and every signal of danger. Without a well-trained nurse it is impossible at the present day properly to care for any serious surgical case, and I gladly bear witness to the intelligence, fidelity, and skill of scores of nurses who have assisted me, and without whom I should have felt as one blade of a scissors without its fellow. SPECIAL OPERATIONS \n_Amputations and Compound Fractures._—Having now traced the different modes of thought which have aided surgical progress in the nineteenth century and the improved means of investigation, let us turn finally to the progress in individual operations. As to amputations and compound fractures, I have already indicated the immense improvements which have followed the introduction of anæsthesia, and especially of antisepsis, which have brought the mortality of amputations down from fifty or sixty per cent."}]}
{"messages": [{"role": "assistant", "content": "As to amputations and compound fractures, I have already indicated the immense improvements which have followed the introduction of anæsthesia, and especially of antisepsis, which have brought the mortality of amputations down from fifty or sixty per cent. to ten or fifteen per cent., and in compound fractures, once so dreaded, since the mortality was not infrequently as high as two out of three, to a relatively insignificant danger. _Tumors._—In no department, perhaps, has the introduction of antisepsis, and the use of catgut and silk ligatures after the antiseptic method, brought about a greater improvement than in operations for tumors. The startling reluctance of Sir Astley Cooper to operate on King George IV. for so simple and small a tumor as a wen, lest erysipelas might follow and even destroy his life, is in marked contrast with the success and therefore the boldness of modern surgeons. Tumors in all parts of the body, whether they be external or internal, whether they involve the wall of the chest or are inside the abdomen, are now removed with almost perfect safety."}]}
{"messages": [{"role": "assistant", "content": "Tumors in all parts of the body, whether they be external or internal, whether they involve the wall of the chest or are inside the abdomen, are now removed with almost perfect safety. Anæsthesia has made it possible to dissect out tumors in so dangerous a region as the neck, where the surgeon is confronted with adhesions to the jugular vein, the carotid artery, and the nerves of the neck and of the arm, with the greatest impunity. Such an operation not uncommonly lasts from three-quarters of an hour to an hour and a half, and involves often the removal of two or three inches of the jugular vein and many of the large nerves, the removal of which a few years ago would have been deemed an impossibility. _Goitre._—One of the most striking instances of progress is operations on goitre. Writing in 1876, the late Professor Samuel D. Gross noted it as something remarkable that Dr."}]}
{"messages": [{"role": "assistant", "content": "Gross noted it as something remarkable that Dr. Green, of Portland, Maine, had removed seven goitres with two deaths, and the late Dr. Maury, of Philadelphia, had extirpated two goitres with one death. In marked contrast to this Professor Kocher, of Berne, in 1895, reported one thousand cases, of which eight hundred and seventy were non-cancerous, and he lost of these last but eleven cases, or a little over one per cent. In 1898 he reported six hundred additional cases, with only one death in the five hundred and fifty-six non-cancerous cases, or a mortality of only 0.1 per cent. It will be seen, therefore, that an operation which a few years ago was excessively fatal has become almost, one might say, a perfectly safe operation."}]}
{"messages": [{"role": "assistant", "content": "It will be seen, therefore, that an operation which a few years ago was excessively fatal has become almost, one might say, a perfectly safe operation. _Surgery of the Bones._—Operations on bones, apart from amputations, show also a similar improvement. In cases of deformity following fracture we now do not hesitate to cut down upon the bone and refracture it or remove the deformed portion, join the ends together, dress the part in plaster of Paris to secure fixation, and have the patient recover with little or no fever and no suppuration. Above the elbow a large nerve runs in a furrow in the arm bone, and in case of fracture this is liable to be torn and a portion of it destroyed. The result of it is paralysis of all the muscles on the back of the forearm from the elbow down and consequent inability to extend either wrist or fingers, making the hand almost useless. In a number of cases the nerve has been sought for and found, but the ends have been too far apart for successful union and sewing them together."}]}
{"messages": [{"role": "assistant", "content": "In a number of cases the nerve has been sought for and found, but the ends have been too far apart for successful union and sewing them together. In such cases we do not hesitate now, in order to bring the two ends of the nerve together, to remove one or two inches of the arm bone, wire the shortened bone, sew the now approximated ends of the nerve together, put the arm in plaster, and as soon as the wound is healed, with appropriate later treatment to the muscles we can obtain in a reasonable number of cases a perfect, or almost perfect, union of the nerves with a re-establishment of the usefulness of the hand. In very many cases the bones are deformed as a result of rickets, and in some cases in consequence of hip-joint disease. In such cases the leg is crooked or flexed, and cannot be used for walking. Such cases of stiff joints and crooked legs are now operated on, one might say, wholesale. At the International Medical Congress, held in Copenhagen in 1884, Professor Macewen, of Glasgow, reported 1800 operations on 1267 limbs in 704 patients, in which he had sawn or chiselled through the bones so as to fracture them, placed them in a straight position, and after a few weeks the bone has become consolidated and the leg or arm made straight."}]}
{"messages": [{"role": "assistant", "content": "At the International Medical Congress, held in Copenhagen in 1884, Professor Macewen, of Glasgow, reported 1800 operations on 1267 limbs in 704 patients, in which he had sawn or chiselled through the bones so as to fracture them, placed them in a straight position, and after a few weeks the bone has become consolidated and the leg or arm made straight. Every one of these operations was successful, excepting five cases, and even these deaths were not due to the operation, but to some other disorder, such as an unexpected attack of pneumonia, diphtheria, or scarlet fever. _Surgery of the Head and Brain._—In the surgery of the head we find one of the most remarkable illustrations of the modern progress of surgery. Fractures of the skull have been the most dangerous and fatal of accidents until within a short time. Of course, many of them must necessarily, even now, be fatal, from the widespread injury to the bones and the brain. But our modern methods, by which we can disinfect the cavities of the ear, the nose, and the mouth, with which these fractures often communicate, and through these avenues become infected, are so successful that such cases, instead of being looked upon as hopeless, are in a majority of instances followed by recovery."}]}
{"messages": [{"role": "assistant", "content": "But our modern methods, by which we can disinfect the cavities of the ear, the nose, and the mouth, with which these fractures often communicate, and through these avenues become infected, are so successful that such cases, instead of being looked upon as hopeless, are in a majority of instances followed by recovery. Even gun-shot wounds, in which the ball may remain inside the cavity of the head, are successfully dealt with, unless the injury produced by the ball has been necessarily fatal from the start. Fluhrer, of New York, has reported a very remarkable case of gun-shot wound, in which the ball entered at the forehead, traversed the entire brain, was deflected at the back of the skull, and then pursued its course farther downward in the brain. By trephining the skull at the back he found the ball, passed a rubber drainage tube through the entire brain from front to back, and had the satisfaction of seeing the patient recover. Until 1884 it was excessively difficult to locate with any degree of accuracy a tumor within the brain, but in that year Dr. Bennett, of London, for the first time accurately located a tumor within the skull without there being the slightest evidence on the exterior of its existence, much less of its location."}]}
{"messages": [{"role": "assistant", "content": "Bennett, of London, for the first time accurately located a tumor within the skull without there being the slightest evidence on the exterior of its existence, much less of its location. Mr. Godlee (surgeons in England are not called “Dr.,” but “Mr.”) trephined the skull at the point indicated, found the tumor, and removed it. True, this patient died, but the possibility of accurately locating a tumor of the brain, reaching it and removing it, was now demonstrated, which is far more important to humanity at large than whether this individual patient survived or not. Since then there have been a very large number of tumors successfully removed. The latest statistics are those of Von Bergmann, of Berlin, in 1898."}]}
{"messages": [{"role": "assistant", "content": "The latest statistics are those of Von Bergmann, of Berlin, in 1898. He collected 273 operations for brain tumors, of which 169 (61.9 per cent.) recovered, and 104 (38.1 per cent.) died. This is by far the best percentage of results so far reported, but there is reason to believe that with the constant improvement in our ability to locate such tumors and in our methods of removing them, the mortality rate will be still further lessened. Even more successful than the surgery of brain tumors has been the surgery of abscess of the brain. I have no available statistics of the exact numbers, but it is certain that several hundred have been operated on, and with even better success than in the case of brain tumors. The most frequent cause for such abscesses is old and neglected disease of the ear."}]}
{"messages": [{"role": "assistant", "content": "The most frequent cause for such abscesses is old and neglected disease of the ear. No child suffering from a “running from the ear,” which is especially apt to follow scarlet fever and other similar disorders, should be allowed to pass from under the most skilled treatment until a cure is effected. This is the commonest cause of abscess of the brain. The inflammation in the ear, which begins in the soft lining of the cavities of the ear, finally extends to the bone, and after years of intermittent discharge, will suddenly develop an abscess of the brain, which, if not relieved, will certainly be fatal. Prompt surgical interference alone can save life, and, happily, though we cannot promise recovery in all, a very large percentage of success is assured. In epilepsy, as a result of injuries of the head, in a moderate number of cases, we can obtain a cure of the disease by operation, but in the great majority of cases, and, one may say, practically in all of the cases in which the epilepsy originates “of itself,” that is to say, without any known cause, it is useless to operate, certainly at least after the epileptic habit has been formed."}]}
{"messages": [{"role": "assistant", "content": "In epilepsy, as a result of injuries of the head, in a moderate number of cases, we can obtain a cure of the disease by operation, but in the great majority of cases, and, one may say, practically in all of the cases in which the epilepsy originates “of itself,” that is to say, without any known cause, it is useless to operate, certainly at least after the epileptic habit has been formed. Possibly were operation done at the very beginning we might obtain better results than experience thus far has shown us is possible. Very many cases of idiocy are constantly brought to surgeons in the hope that something can be done for these lamentable children. Unfortunately, at present surgery holds out but little hope in such cases. In a few exceptional instances it may be best to operate, but a prudent surgeon will decline to do any operation in the vast majority of cases. _Surgery of the Chest and Heart._—The chest is the region of the body which has shown the least progress of all, and yet even here the progress is very marked."}]}
{"messages": [{"role": "assistant", "content": "_Surgery of the Chest and Heart._—The chest is the region of the body which has shown the least progress of all, and yet even here the progress is very marked. When, as a result of pleurisy, fluid accumulates on one side of the chest, even displacing the heart, we now do not hesitate to remove an inch or two of one or more ribs and thoroughly drain the cavity, with not only a reasonable, but in a majority of cases, one may almost say, a certain, prospect of cure. We have also entered upon the road which will lead us in time to a secure surgery of the lung itself. A few cases of abscess, of serious gun-shot wound, attended by otherwise fatal hemorrhage, and even of tubercular cavities in the lungs have been successfully dealt with, but the twentieth century will see, I have no doubt, brilliant results in thoracic surgery. One of the most striking injuries of the chest has recently assumed a new importance, viz., wounds of the heart itself. In several instances an opening has been made in the bony and muscular walls of the chest, and a wound of the heart itself has been sewed up."}]}
{"messages": [{"role": "assistant", "content": "In several instances an opening has been made in the bony and muscular walls of the chest, and a wound of the heart itself has been sewed up. The number is as yet small, but there have been several recoveries, which lead us to believe that here, too, the limits of surgery have by no means been reached. _Surgery of the Abdomen._—Of the abdomen and the pelvis a very different story can be told. These cavities might almost be called the playground of the surgeon, and the remarkable results which have been obtained warrant us in believing that even greater results are in store for us in the future. In the earlier part of this article I spoke of the advantages of the study of the pathological anatomy or the diseased condition of individual organs. Perhaps no better illustration of the value of this can be given than in the studies of appendicitis."}]}
{"messages": [{"role": "assistant", "content": "Perhaps no better illustration of the value of this can be given than in the studies of appendicitis. This operation has been one of the contributions to the surgery of the world in which America has been foremost. While there were one or two earlier papers, Willard Parker, of New York, in 1867, first made the profession listen to him when he urged that abscesses appearing above the right groin should be operated on and the patient’s life saved. But it was not until Fitz, of Boston, in 1888, published his paper, in which he pointed out, as a result of a study of a series of post-mortem examinations of persons dying from such an abscess above the right groin, that the appendix was the seat of the trouble, that this so frequent disease was rightly understood and rightly treated. As a result of the facts gathered in his paper, the treatment was perfectly clear, not only that we ought to operate in cases of abscess, but that in the case of patients suffering from two or more attacks, and often from even one attack of appendicitis, the appendix should be removed to prevent such abscess. The mortality in cases in which such an abscess has formed is, perhaps, quite twenty or twenty-five per cent., whereas, if patients are operated on “in the interval,” that is to say, between attacks, when the abdominal cavity is free from pus, the mortality is scarcely more than two or three per cent., and may be even less than that."}]}
{"messages": [{"role": "assistant", "content": "The mortality in cases in which such an abscess has formed is, perhaps, quite twenty or twenty-five per cent., whereas, if patients are operated on “in the interval,” that is to say, between attacks, when the abdominal cavity is free from pus, the mortality is scarcely more than two or three per cent., and may be even less than that. Surgeons are often asked whether appendicitis is not a fad, and whether our grandfathers ever had appendicitis, etc. As a matter of fact, in my early professional days, appendicitis was well known. It was called “localized peritonitis” or localized “abscess,” but while the disease was very frequent, its relation to the appendix was not recognized until from his study of its pathology an American pointed it out. Even now European surgeons, with a few exceptions, are not alive to the need for operation in such cases. There is little doubt that the great prevalence of grippe during the last few years has increased the number of cases of appendicitis, both of them being catarrhal conditions of the lining membrane of the same continuous tract of the lungs, the mouth, the stomach, and the intestines."}]}
{"messages": [{"role": "assistant", "content": "There is little doubt that the great prevalence of grippe during the last few years has increased the number of cases of appendicitis, both of them being catarrhal conditions of the lining membrane of the same continuous tract of the lungs, the mouth, the stomach, and the intestines. One of the most fatal accidents that can befall a patient is to have an ulcer of the stomach perforate so that the contents of the stomach escape into the general abdominal cavity. Until 1885 no one ventured to operate in such a case. In an inaugural dissertation by Tinker, of Philadelphia, two hundred and thirty-two cases of such perforating ulcers of the stomach were reported, of which one hundred and twenty-three recovered, a mortality of 48.81 per cent. In not a few of them, if prompt instead of late surgical help had been invoked, a very different result would have been reported. If no operation had been done, the mortality would have been one hundred per cent."}]}
{"messages": [{"role": "assistant", "content": "If no operation had been done, the mortality would have been one hundred per cent. In cancer of the stomach itself we are able, as a rule, to make a positive diagnosis only when a perceptible tumor is found. By that time so many adhesions have formed, and the infection has involved the neighboring glands to such an extent, that it is impossible to remove the tumor, but the statistics even here are not without encouragement, at least for comfort if not for life. In many cases the tumor has been removed and the stomach and intestine joined together by various devices, and the mortality, which is necessarily great, has been reduced by Czerny to twelve per cent. and by Carle to seven per cent. Even the entire stomach has been removed in several cases, and recovery has followed in about one-half."}]}
{"messages": [{"role": "assistant", "content": "Even the entire stomach has been removed in several cases, and recovery has followed in about one-half. Most of these patients, however, have died from a return of the disease. When, as a result of swallowing caustic lye or other similar substances, the gullet (the œsophagus) becomes contracted to such an extent that no food can be swallowed, we now establish an opening into the stomach through which a tube is inserted at meal-time, and the patient has his breakfast, dinner, and supper poured into his stomach through the tube. If the stricture of the œsophagus is from malignant disease, of course this only prolongs life by preventing a horrible death by starvation, but in cases in which it is non-malignant life is indefinitely prolonged. The mortality of such an operation is very small. By a freak of nature or by disease the stomach sometimes is narrowed in the middle, forming what is called an “hour-glass stomach.” In such a case we open the abdomen, make an opening into the two parts of the stomach and unite the two so that we re-establish the single cavity of the stomach."}]}
{"messages": [{"role": "assistant", "content": "By a freak of nature or by disease the stomach sometimes is narrowed in the middle, forming what is called an “hour-glass stomach.” In such a case we open the abdomen, make an opening into the two parts of the stomach and unite the two so that we re-establish the single cavity of the stomach. The mortality of the operation is very slight, eight per cent. Again, sometimes the stomach becomes unduly dilated, thus interfering seriously with its function. A number of surgeons in such cases have simply folded over the wall of the stomach upon itself and have sewed the two layers together, taking a plait or “tuck” in the stomach wall, and have restored it to its normal capacity and function. One of the most important advances has been made in the treatment of gall stones. The bile in the gall bladder is in a state of quiescence, which is favorable to a deposit of crystals from the bile."}]}
{"messages": [{"role": "assistant", "content": "The bile in the gall bladder is in a state of quiescence, which is favorable to a deposit of crystals from the bile. These crystals become agglutinated together into larger or smaller solid masses called gall stones. Sometimes the number of these is very small, from one to four or five; sometimes they accumulate in enormous numbers, several hundreds having been reported in a number of instances. When they are small they can escape through the duct of the gall bladder into the bowel and create no disturbance, but when they are large, so that they cannot make their escape, they not uncommonly are causes not only of serious discomfort and prolonged ill-health, but often prove fatal. Nowadays one of the safest operations of surgery is to open the abdomen and the gall bladder and remove this menace to life, and the great majority of such patients recover without any untoward symptoms. Even large abscesses of the liver, and, what is still more extraordinary, large tumors of the liver, are now removed successfully."}]}
{"messages": [{"role": "assistant", "content": "Even large abscesses of the liver, and, what is still more extraordinary, large tumors of the liver, are now removed successfully. A year ago all of the reported cases of tumor of the liver were collected which had been operated from 1888 to 1898, seventy-six in all. The termination in two cases was unknown, but of the other seventy-four, sixty-three recovered and eleven died, a mortality of only 14.9 per cent. The surgery of the intestines by itself is a subject which could well occupy the entire space allowed to this article. I can only, in a very superficial way, outline what has been done. Hernia or rupture is a condition in which through an opening in the abdominal wall a loop of the bowel escapes."}]}
{"messages": [{"role": "assistant", "content": "Hernia or rupture is a condition in which through an opening in the abdominal wall a loop of the bowel escapes. If it can be replaced and kept within the abdomen by a suitable truss this was the best we could do till within the last ten or fifteen years. The safety and the painlessness of modern surgery which have resulted from the introduction of anæsthesia and antisepsis are such that now no person suffering from such a hernia, unless for some special personal reason, should be allowed to rely upon a truss, which is always a more or less treacherous means of retaining the hernia. We operate on all such cases now with impunity. Coley has recently reported a series of six hundred and thirty-nine cases, all of which recovered with the exception of one patient. Even in children, if a truss worn for a reasonable time, a year or so, does not cure the rupture, operation affords an admirable prospect of cure."}]}
{"messages": [{"role": "assistant", "content": "Even in children, if a truss worn for a reasonable time, a year or so, does not cure the rupture, operation affords an admirable prospect of cure. Every now and then a band forms inside the abdomen, stretching like a string across the cavity. If a loop of bowel slips under such a band, it can be easily understood that total arrest of the intestinal contents ensues, a condition incompatible with life. There are other causes for such “intestinal obstruction,” which are too technical to be described in detail, but this may be taken as a type of all. It is impossible, of course, to tell before opening the abdomen precisely the cause of the obstruction, but the fact is quickly determined in most cases. If we open the abdomen promptly, we can cut such a band or remove the other causes of obstruction in the majority of cases, and if the operation has not been too long delayed, the prospect of entire recovery is good."}]}
{"messages": [{"role": "assistant", "content": "If we open the abdomen promptly, we can cut such a band or remove the other causes of obstruction in the majority of cases, and if the operation has not been too long delayed, the prospect of entire recovery is good. The mortality which has followed such operations has been considerable, and by that I mean, say, over twenty per cent., but a very large number of the fatal cases have been lost because the operation has been delayed. In fact, it may be stated very positively that the mere opening of the abdomen to find out precisely the nature of any disease or injury is attended with but little danger. If further surgical interference is required, the danger will be increased proportionately to the extent and gravity of such interference. But “exploratory operations,” as we call them, are now undertaken constantly with almost uniform success. Even in cancer of the bowel, we can prolong life, if we cannot save it."}]}
{"messages": [{"role": "assistant", "content": "Even in cancer of the bowel, we can prolong life, if we cannot save it. Cancer of the bowel sooner or later produces “obstruction” and so destroys life, but in such cases we can either make a permanent opening in the bowel above the cancer, and so relieve the constant pain and distress which is caused by the obstruction, or, in a great many cases, we make an opening in the bowel above the cancer, and another below it, and, by uniting the two openings, if I may so express it, “side-track” the contents of the bowel. If the cancer has no adhesions and the patient’s condition allows of it, we can cut out the entire portion of the bowel containing the cancer, unite the two ends, and thus re-establish the continuity of the intestinal canal. As much as eight feet, nearly one-third of the entire length of the bowel, have been removed by Shepherd, of Montreal, and yet the patient recovered and lived a healthy life. Similarly in gun-shot wounds, stab wounds, etc., involving the intestine, the modern surgeon does not simply stand by with folded hands and give opium and morphine to make the patient’s last few hours or days relatively comfortable, but he opens the abdomen, finds the various perforations, closes them, and recovery has followed even in cases in which as many as seventeen wounds of the intestine have been produced by a gun-shot wound. The kidney, until thirty years ago, was deemed almost beyond our reach, but now entire volumes have been written on the surgery of the kidney, and it is, one might say, a frequent occurrence to see the kidney exposed, sewed fast if it is loose, opened to remove a stone in its interior, drained if there be an abscess, or, if it be hopelessly diseased, it is removed in its entirety."}]}
{"messages": [{"role": "assistant", "content": "The kidney, until thirty years ago, was deemed almost beyond our reach, but now entire volumes have been written on the surgery of the kidney, and it is, one might say, a frequent occurrence to see the kidney exposed, sewed fast if it is loose, opened to remove a stone in its interior, drained if there be an abscess, or, if it be hopelessly diseased, it is removed in its entirety. The other kidney, if not diseased, becomes equal to the work of both. Of the pelvic organs, it would not be becoming to speak in detail, but one operation I can scarcely omit: namely, ovariotomy. One of my old teachers was Washington L. Atlee, who, with his brother, was among the first ovariotomists in this country who placed the operation on a firm foundation. I heard a very distinguished physician in 1862, in a lecture to his medical class, denounce such men as “murderers”; but to-day how differently does the entire profession look upon the operation!"}]}
{"messages": [{"role": "assistant", "content": "I heard a very distinguished physician in 1862, in a lecture to his medical class, denounce such men as “murderers”; but to-day how differently does the entire profession look upon the operation! Instead of condemning the surgeon because he did remove such a tumor, the profession would condemn him because he did not remove it. The operation had its rise in America. Ephraim McDowell, of Kentucky, in 1809, first did the operation which now reflects so much credit upon modern surgery. The mortality of the Atlees was about one in three. Now, owing to the immense improvement introduced by the antiseptic methods, the deaths, in competent hands, are not over five per cent., or even three per cent."}]}
{"messages": [{"role": "assistant", "content": "Now, owing to the immense improvement introduced by the antiseptic methods, the deaths, in competent hands, are not over five per cent., or even three per cent. The limits of this article compel me to stop with the story very imperfectly told, but yet, perhaps, it has been sufficient in detail to show somewhat of the astonishing progress of surgery within the century, but especially within the last quarter of the century. About two decades ago one of the foremost surgeons of London, Mr. Erichsen, said, in a public address, that “surgery had reached its limits.” How short was his vision is shown by the fact that surgery at that time was just at the beginning of its most brilliant modern chapter. We have reached, in many respects, apparently, the limits of our success, but just as anæsthesia and antisepsis and the Röntgen rays have opened new fields wholly unsuspected until they were proclaimed, so I have no doubt that the twentieth century will see means and methods devised which will put to shame the surgery of to-day as much as the surgery of to-day puts to shame that of thirty years ago, and still more of a century ago. The methods by which this will be attained will be by the more thorough and systematic study of disease and injury, so as to better our means of diagnosis, and so prepare us for immediate surgical interference, instead of delaying it, as we now do in many cases, for want of certain knowledge; by the use of new chemical and pharmaceutical means to perfect our antisepsis and possibly to introduce other methods of treatment; but, above all, we shall obtain progress by the exact experimental methods of the laboratory."}]}
{"messages": [{"role": "assistant", "content": "The methods by which this will be attained will be by the more thorough and systematic study of disease and injury, so as to better our means of diagnosis, and so prepare us for immediate surgical interference, instead of delaying it, as we now do in many cases, for want of certain knowledge; by the use of new chemical and pharmaceutical means to perfect our antisepsis and possibly to introduce other methods of treatment; but, above all, we shall obtain progress by the exact experimental methods of the laboratory. We can never make progress except by trying new methods. New methods must be tried either on man or on animals, and as the former is not allowable, the only way remaining to us is to test all new methods, drugs, and applications first upon animals. He who restricts, and, still more, he who would abolish our present experiments upon animals, is, in my opinion, the worst foe to the human race, and to animals, as well, for they, as well as human beings, obtain the benefit derived from the method. He may prate of his humanity, but he is the most cruel man alive. W."}]}
{"messages": [{"role": "assistant", "content": "W. W. KEEN. ELECTRICITY \n\nThe great importance which electricity has attained in many departments of human activity is so constantly evident that we have difficulty in realizing how short is the time which has been occupied in its development. The latter half of the nineteenth century must ever remain memorable, not only for the great advances in nearly all the useful arts, but for the peculiarly rapid electric progress, and the profound effect which it has had upon the lives and business of the people. In the preceding century we find no evidences of the application of electricity to any useful purpose."}]}
{"messages": [{"role": "assistant", "content": "In the preceding century we find no evidences of the application of electricity to any useful purpose. Few of the more important principles of the science were then known. Franklin’s invention of the lightning-rod was not intended to utilize electric force, but to guard life and property from the perils of the thunder-storm. The numerous instructive experiments in frictional electricity, the first-known form of electric manifestation except lightning, made clear certain principles, such as conduction and insulation, and served to distinguish the two opposite electric conditions known as positive and negative. Franklin’s kite experiment confirmed the long-suspected identity of lightning and electric sparks. It was not, however, until the discovery by Alexander Volta, in 1799, of his pile, or battery, that electricity could take its place as an agent of practical value."}]}
{"messages": [{"role": "assistant", "content": "It was not, however, until the discovery by Alexander Volta, in 1799, of his pile, or battery, that electricity could take its place as an agent of practical value. Volta, when he made this great discovery, was following the work of Galvani, begun in 1786. But Galvani in his experiments mistook the effect for the cause, and so missed making the unique demonstration that two different metals immersed in a solution could set up an electric current. Volta, a professor in the University of Pavia and a foreign member of the Royal Society of England, communicated his discovery to the president of the society in March, 1800, and brought to the notice of the world the first means for obtaining a steady flow of electricity. Before this event electric energy had been known to the experimenter in pretty effects of attraction and repulsion of light objects, in fitful flashes of insignificant power, or, as it appeared in nature, in the fearful bursts of energy during a thunder-storm, uncontrolled and erratic. The analogous and closely related phenomena of magnetism had already found an important application in the navigator’s compass."}]}
{"messages": [{"role": "assistant", "content": "The analogous and closely related phenomena of magnetism had already found an important application in the navigator’s compass. The simplest facts of electro-magnetism, upon which much of the later electrical developments depend, remained entirely unknown until near the close of the first quarter of the nineteenth century. Magnetism itself, as exemplified in loadstone or in magnetized iron or steel, had long before been consistently studied by Dr. Gilbert, of Colchester, England, and in 1600 his great work, _De Magnete_, was published. It is a first example, and an excellent one, too, of the application of the inductive method, so fruitful in after-years. The restraints which a superstitious age had imposed upon nature study were gradually removed, and at the beginning of the century just past occasional decided encouragement began to be given to physical research."}]}
{"messages": [{"role": "assistant", "content": "The restraints which a superstitious age had imposed upon nature study were gradually removed, and at the beginning of the century just past occasional decided encouragement began to be given to physical research. It was this condition which put into the hands of Humphry Davy, of the Royal Institution, in London, at the opening of the century, a voltaic battery of some 250 pairs of plates. With this a remarkably fruitful era of electric discovery began. In 1802 Davy first showed the electric arc or “arch” on a small scale between pieces of carbon. He also laid the foundation for future electro-chemical work by decomposing by the battery current potash and soda, and thus isolating the alkali metals, potassium and sodium, for the first time. This was in 1807, and the result was not only to greatly advance the youthful science of chemistry, but to attract the attention of the world to a new power in the hands of the scientific worker, electric current."}]}
{"messages": [{"role": "assistant", "content": "This was in 1807, and the result was not only to greatly advance the youthful science of chemistry, but to attract the attention of the world to a new power in the hands of the scientific worker, electric current. A fund was soon subscribed by “a few zealous cultivators and patrons of science,” interested in the discovery of Davy, and he had at his service in 1801 no less than 2000 cells of voltaic battery. With the intense currents obtained from it he again demonstrated the wonderful and brilliant phenomenon of the electric arc, by first closing the circuit of the battery through terminals of hardwood charcoal and then separating them for a short distance. A magnificent arch of flame was maintained between the separated ends, and the light from the charcoal pieces was of dazzling splendor. Thus was born into the world the electric arc light, of which there are now many hundreds of thousands burning nightly in our own country alone. Davy probably never imagined that his brilliant experiment would soon play so important a part in the future lighting of the world."}]}
{"messages": [{"role": "assistant", "content": "Davy probably never imagined that his brilliant experiment would soon play so important a part in the future lighting of the world. He may never have regarded it as of any practical value. In fact, many years elapsed before any further attempt was made to utilize the light of the electric arc. The reason for this is not difficult to discover. The batteries in existence were crude and gave only their full power for a very short time after the circuit was closed. They were subject to the very serious defect of rapid polarization, whereby the activity was at once reduced."}]}
{"messages": [{"role": "assistant", "content": "They were subject to the very serious defect of rapid polarization, whereby the activity was at once reduced. A long period elapsed before this defect was removed. Davy in his experiments had also noted the very intense heat of the electric arc, and found that but few substances escaped fusion or volatilization when placed in the heated stream between the carbon electrodes. Here again he was pioneer in very important and quite recent electric work, employing the electric furnace, which has already given rise to several new and valuable industries. The conduction of electricity along wires naturally led to efforts to employ it in signalling. As early as 1774 attempts were made by Le Sage, of Geneva, to apply frictional electricity to telegraphy."}]}
{"messages": [{"role": "assistant", "content": "As early as 1774 attempts were made by Le Sage, of Geneva, to apply frictional electricity to telegraphy. His work was followed before the close of the century by other similar proposals. Volta’s discovery soon gave a renewed impetus to these efforts. It was easy enough to stop and start a current in a line of wire connecting two points, but something more than that was requisite. A good receiver, or means for recognizing the presence or absence of current in the wire or circuit, did not exist. The art had to wait for the discovery of the effects of electric current upon magnets and the production of magnetism by such currents."}]}
{"messages": [{"role": "assistant", "content": "The art had to wait for the discovery of the effects of electric current upon magnets and the production of magnetism by such currents. Curiously, even in 1802 the fact that a wire conveying a current would deflect a compass needle was observed by Romagnosi, of Trente, but it was afterwards forgotten, and not until 1819 was any real advance made. It was then that Oersted, of Copenhagen, showed that a magnet tends to set itself at right angles to the wire conveying current and that the direction of turning depends on the direction of the current. The study of the magnetic effects of electric currents by Arago, Ampère, and the production of the electro-magnet by Sturgeon, together with the very valuable work of Henry and others, made possible the completion of the electric telegraph. This was done by Morse and Vail in America, and almost simultaneously by workers abroad, but, before Morse had entered the field, Professor Joseph Henry had exemplified by experiments the working of electric signalling by electro-magnets over a short line. It was Henry, in fact, who first made a practically useful electro-magnet of soft iron."}]}
{"messages": [{"role": "assistant", "content": "It was Henry, in fact, who first made a practically useful electro-magnet of soft iron. The history of the electric telegraph teaches us that to no single individual is the invention due. The Morse system had been demonstrated in 1837, but not until 1844 was the first telegraph line built. It connected Baltimore and Washington, and the funds for defraying its cost were only obtained from Congress after a severe struggle. This can easily be understood, for electricity had not up to that time ever been shown to have any practical usefulness. The success of the Morse telegraph was soon followed by the establishment of telegraph lines as a means of communication between all the large cities and populous districts."}]}
{"messages": [{"role": "assistant", "content": "The success of the Morse telegraph was soon followed by the establishment of telegraph lines as a means of communication between all the large cities and populous districts. Scarcely ten years elapsed before the possibility of a transatlantic telegraph was mooted. The cable laid in 1858 was a failure. A few words passed, and then the cable broke down completely. This was found to be due to defects in construction. A renewed effort to lay a cable was made in 1866, but disappointment again followed: the cable broke in mid-ocean and the work again ceased."}]}
{"messages": [{"role": "assistant", "content": "A renewed effort to lay a cable was made in 1866, but disappointment again followed: the cable broke in mid-ocean and the work again ceased. The great task was successfully accomplished in the following year, and the pluck and pertinacity of those who were staking their capital, if not their reputations for business sagacity, were amply rewarded. Even the lost cable of 1866 was found, spliced to a new cable, and completed soon after as a second working line. The delicate instruments for the working of these long cables were due to the genius of Sir William Thomson, now Lord Kelvin, whose other instruments for electrical measurement have for years been a great factor in securing precision both in scientific and practical testing. The number of cables joining the Eastern and Western hemispheres has been increased from time to time, and the opening of a new cable is now an ordinary occurrence, calling for little or no especial note. The introduction of the electric telegraph was followed by the invention of various signalling systems, the most important being the fire-alarm telegraph, as suggested by Channing and worked out by Farmer."}]}
{"messages": [{"role": "assistant", "content": "The introduction of the electric telegraph was followed by the invention of various signalling systems, the most important being the fire-alarm telegraph, as suggested by Channing and worked out by Farmer. We now, also, have automatic clock systems, in which a master clock controls or gives movement to the hands of distant clock dials by electric currents sent out over the connecting or circuit wires. Automatic electric signals are made when fire breaks out in a building, and alarms are similarly rung when a burglar breaks in. Not only do we have telegraphs which print words and characters, as in the stock “ticker,” but in the form known as the telautograph, invented by Dr. Elisha Gray, the sender writes his message, which writing is at the same time being reproduced at the receiving end of the line. Even pictures for drawings are “wired” by special instruments."}]}
{"messages": [{"role": "assistant", "content": "Even pictures for drawings are “wired” by special instruments. The desirability of making one wire connecting two points do a large amount of work, and thus avoiding the addition of new lines, has led to two remarkable developments of telegraphy. In the duplex, quadruplex, and multiplex systems several messages may at the same time be traversing a single wire line without interference one with the other. In the rapid automatic systems the working capacity of the line is increased by special automatic transmitting machines and rapid recorders, and the electric impulses in the line itself follow each other with great speed. Improvement in this field has by no means ceased, and new systems for rapid transmission are yet being worked out. The object is to enlarge the carrying capacity of existing lines connecting large centres of population."}]}
{"messages": [{"role": "assistant", "content": "The object is to enlarge the carrying capacity of existing lines connecting large centres of population. The names of Wheatstone, Stearns, Edison, and Delaney are prominent in connection with this work. For use in telegraphy the originally crude forms of voltaic battery, such as Davy used, were replaced by the more perfect types such as the constant battery of Daniell, the nitric-acid battery of Grove, dating from 1836, and the carbon battery of Bunsen, first brought out in 1842. Such was the power of the Grove and Bunsen batteries that attention was again called to the electric arc and to the possibility of its use for electric illumination. Accordingly, we find that suggestions were soon made for electric-arc lamps, to be operated by these more powerful and constant sources of electric current. The first example of a working type of an arc lamp was that brought to notice by W."}]}
{"messages": [{"role": "assistant", "content": "The first example of a working type of an arc lamp was that brought to notice by W. E. Staite, in 1847, and his description of the lamp and the conditions under which it could be worked is a remarkably exact and full statement, considering the time of its appearance. Staite even anticipated the most recent phase of development in arc lighting, namely, the enclosure of the light in a partially air-tight globe, to prevent too rapid waste of the carbons by combustion in the air. In a public address at Newcastle-on-Tyne, in 1847, he advocated the use of the arc, so enclosed, in mines, as obviating the danger of fire. But it was a long time before the electric arc acquired any importance as a practical illuminant."}]}
{"messages": [{"role": "assistant", "content": "But it was a long time before the electric arc acquired any importance as a practical illuminant. There was, indeed, no hope of its success so long as the current had to be obtained from batteries consuming chemicals and zinc. The expense was too great, and the batteries soon became exhausted. In spite of this fact, occasional exhibitions of arc lighting were made, notably in 1856, by Lacassagne and Thiers, in the streets of Paris. For this service they had invented an arc lamp involving what is known as the differential principle, afterwards applied so extensively to arc lamps. The length of the arc or the distance between the carbons of the lamp was controlled with great nicety, and the light thus rendered very steady."}]}
{"messages": [{"role": "assistant", "content": "The length of the arc or the distance between the carbons of the lamp was controlled with great nicety, and the light thus rendered very steady. Even as late as 1875 batteries were occasionally used to work single electric arc lamps for public exhibitions, or for demonstration purposes in the scientific departments of schools. The discovery of the means of efficiently generating electricity from mechanical power constitutes, however, the key-note of all the wonderful electrical work of the closing years of the nineteenth century. It made electrical energy available at low cost. Michael Faraday, a most worthy successor of Davy at the Royal Institution, in studying the relations between electric currents and magnets, made the exceedingly important observation that a wire, if moved in the field of a magnet, would yield a current of electricity. Simple as the discovery was, its effect has been stupendous."}]}
{"messages": [{"role": "assistant", "content": "Simple as the discovery was, its effect has been stupendous. Following his science for its own sake, he unwittingly opened up possibilities of the greatest practical moment. The fundamental principle of the future dynamo electric machine was discovered by him. This was in 1831. Faraday’s investigations were so complete and his deductions so masterly, that little was left to be done by others. Electro-magnetism was supplemented by magneto-electricity."}]}
{"messages": [{"role": "assistant", "content": "Electro-magnetism was supplemented by magneto-electricity. Both the electric motor and the dynamo generator were now potentially present with us. Faraday contented himself with pointing the way, leaving the technical engineer to follow. In one of Faraday’s experiments a copper disk mounted on an axis passing through its centre was revolved between the poles of a large steel magnet. A wire touched the periphery of the disk at a selected position with respect to the magnet, and another was in connection with the axis. These wires were united through a galvanometer or instrument for detecting electric current."}]}
{"messages": [{"role": "assistant", "content": "These wires were united through a galvanometer or instrument for detecting electric current. A current was noted as present in the circuit so long as the disk was turned. Here, then, was the embryo dynamo. The century closed with single dynamo machines of over 5000 horse-power capacity, and with single power stations in which the total electric generation by such machines is 75,000 to 100,000 horse-power. So perfect is the modern dynamo that out of 1000 horse-power expended in driving it, 950 or more may be delivered to the electric line as electric energy. The electric motor, now so common, is a machine like the dynamo, in which the principle of action is simply reversed; electric energy delivered from the lines becomes again mechanical motion or power."}]}
{"messages": [{"role": "assistant", "content": "The electric motor, now so common, is a machine like the dynamo, in which the principle of action is simply reversed; electric energy delivered from the lines becomes again mechanical motion or power. Soon after Faraday’s discoveries in magneto-electricity attempts were made to construct generators of electricity from power. But the machines were small, crude, and imperfect, and the results necessarily meagre. Pixii, in Paris, one year after Faraday’s discovery was announced, made a machine which embodied in its construction a simple commutator for giving the currents a single direction of flow. This is the prototype of the commutators now found on what are called continuous-current dynamos. After Pixii followed Saxton, Clarke, Wheatstone and Cooke, Estohrer, and others, but not until 1854 was any very notable improvement made or suggested."}]}
{"messages": [{"role": "assistant", "content": "After Pixii followed Saxton, Clarke, Wheatstone and Cooke, Estohrer, and others, but not until 1854 was any very notable improvement made or suggested. In that year Soren Hjorth, of Copenhagen, described in a patent specification the principle of causing the electric currents generated to traverse coils of wire so disposed as to reinforce the magnetic field of the machine itself. A year subsequently the same idea was again more clearly set out by Hjorth. This is the principle of the modern self-exciting dynamo, the field magnets of which, very weak at the start, are built up or strengthened by the currents from the armature or revolving part of the machine in which power is consumed to produce electricity. In 1856 Dr. Werner Siemens, of Berlin, well known as a great pioneer in the electric arts, brought out the Siemens armature, an innovation more valuable than any other made up to that time."}]}
{"messages": [{"role": "assistant", "content": "Werner Siemens, of Berlin, well known as a great pioneer in the electric arts, brought out the Siemens armature, an innovation more valuable than any other made up to that time. This was subsequently used in the powerful machines of Wilde and Ladd. It still survives in magneto call-bell apparatus for such work as telephone signalling, in exploders for mines and blasting, and in the simpler types of electroplating dynamos. The decade between 1860 and 1870 opened a new era in the construction and working of dynamo machines and motors. It is notable for two advances of very great value and importance. Dr."}]}
{"messages": [{"role": "assistant", "content": "Dr. Paccinotti, of Florence, in 1860, described a machine by which true continuous currents resembling battery currents could be obtained. Up to that time machines gave either rapidly alternating or fluctuating currents, not steady currents in one direction. The Paccinotti construction, in modified forms, is now almost universally employed in dynamo machines, and even where the form is now quite different the Paccinotti type has been at least the forerunner, and has undergone modifications to suit special ends in view. Briefly, Paccinotti made his armature of a ring of iron with iron projections between which the coils of insulated wire were wound. Although full descriptions of Paccinotti’s ring armature and commutator were given out in 1864, his work attracted but little attention until Gramme, in Paris, about 1870, brought out the relatively perfect Gramme machine."}]}
{"messages": [{"role": "assistant", "content": "Although full descriptions of Paccinotti’s ring armature and commutator were given out in 1864, his work attracted but little attention until Gramme, in Paris, about 1870, brought out the relatively perfect Gramme machine. In the mean time the other great development of the decade took place. Although Hjorth had, as stated before, put forward the idea that a dynamo generator might itself furnish currents for magnetizing its own magnets, this valuable suggestion was not apparently worked out until 1866, when a machine was constructed for Sir Charles Wheatstone. This appears to have been the first self-exciting machine in existence. Wheatstone read a paper before the Royal Society in February, 1867, “On the Augmentation of the Power of a Magnet by the Reaction thereon of Currents Induced by the Magnet Itself.” This action later became known as the reaction principle in dynamo machines. As often happens, the idea occurred to other workers in science almost simultaneously, and Dr."}]}
{"messages": [{"role": "assistant", "content": "As often happens, the idea occurred to other workers in science almost simultaneously, and Dr. Werner Siemens also read a paper in Berlin about a month earlier than that of Wheatstone, clearly describing the reaction principle. Furthermore, a patent specification had been filed in the British Patent Office by S. A. Varley, December 24, 1866, clearly showing the same principle of action, and he was, therefore, the first to put the matter on record. The time was ripe for the appearance of machines closely resembling the types now in such extended use."}]}
{"messages": [{"role": "assistant", "content": "The time was ripe for the appearance of machines closely resembling the types now in such extended use. Gramme, in 1870, adopting a modified form of the Paccinotti ring and commutator, and employing the reaction principle, first succeeded in producing a highly efficient, compact, and durable continuous-current dynamo. The Gramme machine was immediately recognized as a great technical triumph. It was in a sense the culmination of many years of development, beginning with the early attempts immediately following Faraday’s discovery, already referred to. Gramme constructed his revolving armature of a soft iron wire ring, upon which ring a series of small coils of insulated wire were wound in successive radial planes. These coils were all connected with a continuous wire and from the junctions of the coils one with another connections were taken to a range of copper bars insulated from each other, constituting the commutator."}]}
{"messages": [{"role": "assistant", "content": "These coils were all connected with a continuous wire and from the junctions of the coils one with another connections were taken to a range of copper bars insulated from each other, constituting the commutator. In 1872 Von Hefner Alteneck, in Berlin, modified the ring winding of Gramme and produced the “drum winding,” which avoided the necessity for threading wire through the centre of the iron ring as in the Gramme construction. The several coils of the drum were still connected, as in Gramme’s machine, to the successive strips of the commutator. In modern dynamos and motors the armature, usually constructed of sheet-iron punchings, is a ring with projections as in Paccinotti’s machine, and the coils of wire are in most cases wound separately and then placed in the spaces between the projections, constituting in fact a form of drum winding. In the early 70’s a few Gramme ring and Siemens drum machines had been applied to the running of arc lights, one machine for each light. There were also some Gramme machines in use for electroplating."}]}
{"messages": [{"role": "assistant", "content": "There were also some Gramme machines in use for electroplating. At the Centennial Exhibition, held at Philadelphia in 1876, but two exhibits of electric-lighting apparatus were to be found. Of these one was the Gramme and the other the Wallace-Farmer exhibit. The Wallace-Farmer dynamo machine is a type now obsolete. It was not a good design, but the Wallace exhibit contained other examples reflecting great credit on this American pioneer in dynamo work. Some of these machines were very similar in construction to later forms which went into very extensive use."}]}
{"messages": [{"role": "assistant", "content": "Some of these machines were very similar in construction to later forms which went into very extensive use. The large search-lights occasionally used in night illumination during the exhibitions were operated by the current from Wallace-Farmer machines. The Gramme exhibit was a remarkable exhibit for its time. Though not extensive, it was most instructive. There were found in it a dynamo running an arc lamp; a large machine for electrolytic work, such as electroplating or electrotyping, and, most novel and interesting of all, one Gramme machine driven by power was connected to another by a pair of wires and the second run as a motor. This in turn drove a centrifugal-pump, and raised water which flowed in a small fall or cataract."}]}
{"messages": [{"role": "assistant", "content": "This in turn drove a centrifugal-pump, and raised water which flowed in a small fall or cataract. A year or two previously the Gramme machine had been accidentally found to be as excellent an electric motor as it was a generating dynamo. The crude motors of Jacobi, Froment, Davenport, Page, Vergnes, Gaume, and many others, were thus rendered obsolete at a stroke. The first public demonstration of the working of one Gramme machine by another was made by Fontaine at the Vienna Exhibition of 1873. Here, then, was a foreshadowing of the great electric-power transmission plants of to-day; the suggestion of the electric station furnishing power as well as light, and, to a less degree, the promise of future railways using electric power. Replace the centrifugal pump of this modest exhibit by a turbine wheel, reverse the flow of water so as to cause it to drive the electric motor so that the machine becomes a dynamo, and, in like manner, make of the dynamo a motor, and we exemplify in a simple way recent great enterprises using water-power for the generation of current to be transmitted over lines to distant electric motors or lights."}]}
{"messages": [{"role": "assistant", "content": "Replace the centrifugal pump of this modest exhibit by a turbine wheel, reverse the flow of water so as to cause it to drive the electric motor so that the machine becomes a dynamo, and, in like manner, make of the dynamo a motor, and we exemplify in a simple way recent great enterprises using water-power for the generation of current to be transmitted over lines to distant electric motors or lights. The Centennial Exhibition also marks the beginning—the very birth, it may be said—of an electric invention destined to become, before the close of the century, a most potent factor in human affairs. The speaking telephone of Alexander Graham Bell was there exhibited for the first time to the savants, among whom was the distinguished electrician and scientist Sir William Thomson. For the first time in the history of the world a structure of copper wire and iron spoke to a listening ear. Nay, more, it both listened to the voice of the speaker and repeated the voice at a far-distant point. The instruments were, moreover, the acme of simplicity."}]}
{"messages": [{"role": "assistant", "content": "The instruments were, moreover, the acme of simplicity. Within a year many a boy had constructed a pair of telephones at an expenditure for material of only a few pennies. In its first form the transmitting telephone was the counterpart of the receiver, and they were reversible in function. The transmitter was in reality a minute dynamo driven by the aërial voice waves; the receiver, a vibratory motor worked by the vibratory currents from the transmitter and reproducing the aërial motions. This arrangement, most beautiful in theory, was only suited for use on short lines, and was soon afterwards replaced by various forms of carbon microphone transmitter, to the production of which many inventors had turned their attention, notably Edison, Hughes, Blake, and Hunnings. In modern transmitters the voice wave does not furnish the power to generate the telephone current, but only controls the flow of an already existing current from a battery."}]}
{"messages": [{"role": "assistant", "content": "In modern transmitters the voice wave does not furnish the power to generate the telephone current, but only controls the flow of an already existing current from a battery. In this way the effects obtainable may be made sufficiently powerful for transmission to listeners 1500 miles away. There is no need to dwell here upon the enormous saving of time secured by the telephone and the profound effect its introduction has had upon business and social life. The situation is too palpable. Nevertheless, few users of this wonderful invention realize how much thought and skill have been employed in working out the details of exchange switchboards, of signalling devices, of underground cables and overhead wires, and of the speaking instruments themselves. Few of those who talk between Boston and Chicago know that in doing so they have for the exclusive use of their voices a total of over 1,000,000 pounds of copper wire in the single line."}]}
{"messages": [{"role": "assistant", "content": "Few of those who talk between Boston and Chicago know that in doing so they have for the exclusive use of their voices a total of over 1,000,000 pounds of copper wire in the single line. There probably now exist in the United States alone between 75,000 and 100,000 miles of hard-drawn copper wire for long-distance telephone service, and over 150,000 miles of wire in underground conduits. There are upward of three-quarters of a million telephones in the United States, and, including both overhead and underground lines, a total of more than half a million miles of wire. Approximately one thousand million conversations are annually conveyed. The possibility of sub-oceanic telephoning is frequently discussed, but the problem thus far is not solved. It involves grave difficulties, and we may hope that its solution is to be one of the advances which will mark the twentieth century’s progress."}]}
{"messages": [{"role": "assistant", "content": "It involves grave difficulties, and we may hope that its solution is to be one of the advances which will mark the twentieth century’s progress. The advent of the telephone in 1876 seemed to stimulate invention in the electric field to a remarkable degree. Its immediate commercial success probably acted also to inspire confidence in other proposed electric enterprises. Greater attention than ever before began to be given to the problem of electric lighting. An electric arc lamp, probably the only one in regular use, had been installed at Dungeness Light-house in 1862, after a long set of trials and tests. It was fed by a Holmes magneto-electric machine of the old type, very large and cumbrous for the work."}]}
{"messages": [{"role": "assistant", "content": "It was fed by a Holmes magneto-electric machine of the old type, very large and cumbrous for the work. Numerous changes and improvements had before 1878 been made in arc lamps by Serrin, Duboscq, and many others. But the display of electric light during the Paris Exposition of 1878 was the first memorable use of the electric light on a large scale. The splendid illumination of the Avenue de l’Opéra was a grand object-lesson. The source of light was the “electric candle” of Paul Jablochkoff, a Russian engineer. It was a strikingly original and simple arc lamp."}]}
{"messages": [{"role": "assistant", "content": "It was a strikingly original and simple arc lamp. Instead of placing the two carbons point to point, as had been done in nearly all previous lamps, he placed them side by side, with a strip of baked kaolin between them. The candle so formed was supported in a suitable holder, whereby, at the lower end, the two parallel carbons were connected with the circuit terminals. By a suitable device the arc was started at the top and burned down. The electric candle seemed to solve the problem of allowing complicated mechanism for feeding the carbons to be discarded; but it survived only a short time. Owing to unforeseen difficulties it was gradually abandoned, after having served a great purpose in directing the attention of the world to the possibilities of the electric arc in lighting."}]}
{"messages": [{"role": "assistant", "content": "Owing to unforeseen difficulties it was gradually abandoned, after having served a great purpose in directing the attention of the world to the possibilities of the electric arc in lighting. Inventors in America were not idle. By the close of 1878, Brush, of Cleveland, had brought out his series system of arc lights, including special dynamos, lamps, etc., and by the middle of 1879 had in operation machines each capable of maintaining sixteen arc lamps on one wire. This was, indeed, a great achievement for that time. Weston, of Newark, had also in operation circuits of arc lamps, and the Thomson-Houston system had just started in commercial work with eight arc lamps in series from a single dynamo. Maxim and Fuller, in New York, were working arc lamps from their machines, and capital was being rapidly invested in new enterprises for electric lighting."}]}
{"messages": [{"role": "assistant", "content": "Maxim and Fuller, in New York, were working arc lamps from their machines, and capital was being rapidly invested in new enterprises for electric lighting. Some of the great electric manufacturing concerns of to-day had their beginning at that time. Central lighting stations began to be established in cities, and the use of arc lights in street illumination and in stores grew rapidly. More perfect forms of arc lamps were invented, better generating dynamos and regulating apparatus brought out. Factories for arc-light carbon making were built. The first special electrical exhibition was held in Paris in 1881."}]}
{"messages": [{"role": "assistant", "content": "The first special electrical exhibition was held in Paris in 1881. In the early 80’s, also, the business of arc lighting had become firmly established, and soon the bulk of the work was done under two of the leading systems. These were afterwards brought together under one control, thus securing in the apparatus manufactured a combination of the good features of both. Until about 1892 nearly all the arc lamps in use were worked under the series system, in which the lights are connected one after another on a circuit and traversed by the same current. This current has a standard value, or is a constant current. Sometimes as many as a hundred lamps were on one wire."}]}
{"messages": [{"role": "assistant", "content": "Sometimes as many as a hundred lamps were on one wire. As the mains for the supply of incandescent lamps at constant pressure, or potential, were extended, attention was more strongly turned to the possibility of working arc lights therefrom. Within a few years of the close of the century this placing of arc lamps in branches from the same mains which supply incandescent lamps became common, and the enclosure of the arc in a partially air-tight globe, a procedure advocated by Staite, in 1847, was revived by Howard, Marks, and others for saving carbons and attention to the lamp. The enclosed arc lamp was also found to be especially adapted to use in branches of the incandescent lamp circuits, which had in cities become greatly extended. The increasing employment of alternating currents in the distribution of electric energy has led also to the use of alternating current arc lamps, and special current-regulating apparatus is now being applied on a large scale to extended circuits of these lamps. It can be seen from these facts that the art is still rapidly progressing and the field ever widening."}]}
{"messages": [{"role": "assistant", "content": "It can be seen from these facts that the art is still rapidly progressing and the field ever widening. A little over twenty years ago practically no arc lamps were used. At the close of the century, they were numbered by hundreds of thousands. The annual consumption of carbons in this country has reached two hundred millions. Almost simultaneously with the beginning of the commercial work of arc lighting, Edison, in a successful effort to provide a small electric lamp for general distribution in place of gas, brought to public notice his carbon filament incandescent lamp. A considerable amount of progress had previously been made by various workers in attempting to reduce the volume of light in each lamp and increase the number of lights for a given power expended."}]}
{"messages": [{"role": "assistant", "content": "A considerable amount of progress had previously been made by various workers in attempting to reduce the volume of light in each lamp and increase the number of lights for a given power expended. Forms of incandescent arc lamps, or semi-incandescent lamps, were tried on a considerable scale abroad, but none have survived. So, also, many attempts to produce a lamp giving light by pure incandescence of solid conductors proved for the most part abortive. Edison himself worked for nearly two years on a lamp based upon the old idea of incandescent platinum strips or wires, but without success. The announcement of this lamp caused a heavy drop in gas shares, long before the problem was really solved by a masterly stroke in his carbon filament lamp. Curiously, the nearest approach to the carbon filament lamp had been made in 1845, by Starr, an American, who described in a British patent specification a lamp in which electric current passed through a thin strip of carbon kept it heated while surrounded by a glass bulb in which a vacuum was maintained."}]}
{"messages": [{"role": "assistant", "content": "Curiously, the nearest approach to the carbon filament lamp had been made in 1845, by Starr, an American, who described in a British patent specification a lamp in which electric current passed through a thin strip of carbon kept it heated while surrounded by a glass bulb in which a vacuum was maintained. Starr had exhibited his lamps to Faraday, in England, and was preparing to construct dynamos to furnish electric current for them in place of batteries, but sudden death put an end to his labors. The specification describing his lamp is perhaps the earliest description of an incandescent lamp of any promise, and the subsequently recorded ideas of inventors up to the work of Edison seem now to be almost in the nature of retrograde movements. None of them were successful commercially. Starr, who was only twenty-five years of age, is reported to have died of overwork and worry in his efforts to perfect his invention. His ideas were evidently far in advance of his time."}]}
{"messages": [{"role": "assistant", "content": "His ideas were evidently far in advance of his time. The Edison lamp differed from those which preceded it in the extremely small section of the carbon strip rendered hot by the current, and in the perfection of the vacuum in which it was mounted. The filament was first made of carbonized paper, and afterwards of bamboo carbon. The modern incandescent lamp has for years past been provided with a filament made by a chemical process. The carbon formed is exceedingly homogeneous and of uniform electric resistance. Edison first exhibited his lamp in his laboratory at Menlo Park, New Jersey, in December, 1879; but before it could be properly utilized an enormous amount of work had to be done."}]}
{"messages": [{"role": "assistant", "content": "Edison first exhibited his lamp in his laboratory at Menlo Park, New Jersey, in December, 1879; but before it could be properly utilized an enormous amount of work had to be done. His task was not merely the improvement of an art already existing; it was the creation of a new art. Special dynamo machines had to be invented and constructed for working the lamps; switches were needed for connecting and disconnecting lamps and groups of lamps; meters for measuring the consumption of electric energy were wanted; safety fuses and cut-offs had to be provided; electroliers or fixtures to support the lamp were required; and, lastly, a complete system of underground mains with appurtenances was a requisite for city plants. Even the steam-engines for driving the dynamos had to be remodelled and improved for electric work, and ten years of electric lighting development did more towards the refinement and perfection of steam-engines than fifty years preceding. Steadiness of lights meant the preservation of steady speed in the driving machinery. The Pearl Street station in New York City was the first installation for the supply of current for incandescent lighting in a city district."}]}
{"messages": [{"role": "assistant", "content": "The Pearl Street station in New York City was the first installation for the supply of current for incandescent lighting in a city district. The constant pressure dynamos were gradually improved and enlarged. The details of all parts of the system were made more perfect, and in the hands of Edison and others the incandescent lamps, originally of high cost, were much cheapened and the quality of the production was greatly improved. Lamps originally cost one dollar each. The best lamps that are made can be had at present for about one-fifth that price. Millions of incandescent lamps are annually manufactured."}]}
{"messages": [{"role": "assistant", "content": "Millions of incandescent lamps are annually manufactured. Great lighting stations furnish the current for the working of these lamps, some stations containing machinery aggregating many thousands of horse-power capacity. Not only do these stations furnish electric energy for the working of arc lamps and incandescent lamps, but, in addition, for innumerable motors ranging in size from the small desk fan of one-tenth horse-power up to those of hundreds of horse-power. The larger sizes replace steam or hydraulic power for elevators, and many are used in shops and factories for driving machinery such as printing-presses, machinery tools, and the like. In spite of the fact that it was well known that a good dynamo when reversed could be made a source of power, few electric motors were in use until a considerable time after the establishment of the first lighting stations. Even in 1884, at the Philadelphia Electrical Exhibition, only a few electric motors were shown."}]}
{"messages": [{"role": "assistant", "content": "Even in 1884, at the Philadelphia Electrical Exhibition, only a few electric motors were shown. Not until 1886 or thereafter did the “motor load” of an electric station begin to be a factor in its business success. The motors supplied are an advantageous adjunct, inasmuch as they provide a day load, increasing the output of the station at a time when the lighting load is small and when the machinery in consequence would, without them, have remained idle. The growth of the application of electric motors in the closing years of the century has been phenomenal, even leaving out of consideration their use in electric railways. Twenty years ago an electric motor was a curiosity; fifty years ago crude examples run by batteries were only to be occasionally found in cabinets of scientific apparatus. Machinery Hall, at the Centennial Exhibition of 1876, typified the mill of the past, never again to be reproduced, with its huge engine and lines of heavy shafting and belts conveying power to the different tools or machines in operation."}]}
{"messages": [{"role": "assistant", "content": "Machinery Hall, at the Centennial Exhibition of 1876, typified the mill of the past, never again to be reproduced, with its huge engine and lines of heavy shafting and belts conveying power to the different tools or machines in operation. The modern mill or factory has its engines and dynamos located wherever convenient, its electric lines and numerous motors connected thereto, and each of them either driving comparatively short lines of shafting or attached to drive single pieces of machinery. The wilderness of belts and pulleys which used to characterize a factory is gradually being cleared away, and electric distribution of power substituted. Moreover, the lighting of the modern mill or factory is done from the same electric plant which distributes power. The electric motor has already partly revolutionized the distribution of power for stationary machinery, but as applied to railways in place of animal power the revolution is complete. The period which has elapsed since the first introduction of electric railways is barely a dozen years."}]}
{"messages": [{"role": "assistant", "content": "The period which has elapsed since the first introduction of electric railways is barely a dozen years. It is true that a few tentative experiments in electric traction were made some time in advance of 1888, notably by Siemens, in Berlin, in 1879 and 1880, by Stephen D. Field, by T. A. Edison, at Menlo Park, by J. C."}]}
{"messages": [{"role": "assistant", "content": "C. Henry, by Charles A. Van Depoele, and others. If we look farther back we find efforts such as that of Farmer, in 1847, to propel railway cars by electric motors driven by currents from batteries carried on the cars. These efforts were, of course, doomed to failure, for economical reasons. Electric energy from primary batteries was too costly, and if it had been cheaper, the types of electric motor used yielded so small a return of power for the electric energy spent in driving them that commercial success was out of the question."}]}
{"messages": [{"role": "assistant", "content": "Electric energy from primary batteries was too costly, and if it had been cheaper, the types of electric motor used yielded so small a return of power for the electric energy spent in driving them that commercial success was out of the question. These early efforts were, however, instructive, and may now be regarded as highly suggestive of later work. Traction by the use of storage batteries carried on an electric car has been tried repeatedly, but appears not to be able to compete with systems of direct supply from electric lines. The plan survives, however, in the electric automobile, many of which have been put into service within a year or two. The electric automobile is not well fitted for country touring; it is best adapted to cities, where facilities for charging and caring for the batteries can be had. Moreover, the electric carriage is of all automobile carriages the most easily controlled, most ready; it emits no smell or hot gases and is nearly noiseless."}]}
{"messages": [{"role": "assistant", "content": "Moreover, the electric carriage is of all automobile carriages the most easily controlled, most ready; it emits no smell or hot gases and is nearly noiseless. About 1850, Hall, a well-known instrument maker of Boston, catalogued a small toy electric locomotive dragging a car upon rails which were insulated and connected with a stationary battery of two Grove cells. This arrangement was sold as a piece of scientific apparatus, and appears to be the first example of an electrically driven vehicle connected by rolling contacts to an immovable energy source. Other early experimenters, such as Siemens, Field, and Daft, subsequently to Hall, used in actual railway work the supply by insulated tracks. This was supplanted later by overhead insulated wires or by the insulated third rail. Siemens & Halske, of Berlin, used a special form of overhead supply in 1881, and during the electrical exhibition in Paris in that year, a street tramway line was run by them."}]}
{"messages": [{"role": "assistant", "content": "Siemens & Halske, of Berlin, used a special form of overhead supply in 1881, and during the electrical exhibition in Paris in that year, a street tramway line was run by them. Later, Edison experimented with a third-rail-supply line at Menlo Park; and at Portrush, in Ireland, an actual railway was put in operation by Siemens & Halske, using the third-rail system. This was about 1883. The power of the Portrush railway was that of a water-wheel driving the generating dynamo. The modern overhead trolley, or under-running trolley, as it is called, seems to have been first invented by Van Depoele, and used by him in practical electric railway work about 1886 and thereafter. The universality of this invention for overhead supply marks the device as a really important advance in the art of electric traction."}]}
{"messages": [{"role": "assistant", "content": "The universality of this invention for overhead supply marks the device as a really important advance in the art of electric traction. Van Depoele was also a pioneer in the use of an underground conduit, which he employed successfully in Toronto in 1884. The names of Edward M. Bentley and Walter H. Knight stand out prominently in connection with the first use of an underground conduit, tried under their plans in August, 1884, at Cleveland, on the tracks of the horse-railway company. We have barely outlined the history of the electric-motor railway up to the beginning of a period of wonderful development, resulting in the almost complete replacement by electric traction of horse traction or tramway lines, all within an interval of scarcely more than ten years."}]}
{"messages": [{"role": "assistant", "content": "We have barely outlined the history of the electric-motor railway up to the beginning of a period of wonderful development, resulting in the almost complete replacement by electric traction of horse traction or tramway lines, all within an interval of scarcely more than ten years. The year 1888 may be said to mark the beginning of this work, and in that year the Sprague Company, with Frank J. Sprague at its head, put into operation the electric line at Richmond, Virginia, using the under-running trolley. Mr. Sprague had been associated with Edison in early traction work, and was well known in connection with electric-motor work in general. The Richmond line was the first large undertaking."}]}
{"messages": [{"role": "assistant", "content": "The Richmond line was the first large undertaking. It had about thirteen miles of track, numerous curves, and grades of from three to ten per cent. The enterprise was one of great hardihood, and but for ample financial backing and determination to spare no effort or expenditure conducive to success, must certainly have failed. The motors were too small for the work, and there had not been found any proper substitute for the metal commutator brushes on the motors—a source of endless trouble and of an enormous expense for repairs. Nevertheless, the Richmond installation, kept in operation as it was in spite of all difficulties, served as an object-lesson, and had the effect of convincing Mr. Henry M."}]}
{"messages": [{"role": "assistant", "content": "Henry M. Whitney and the directors of the West End Street Railway, of Boston, of the feasibility of equipping the entire railway system of Boston electrically. Meanwhile the merging of the Van Depoele and Bentley-Knight interests into the Thomson-Houston Electric Light Company brought a new factor into the field, the Sprague interests being likewise merged with the Edison General Electric Company. The West End Company, with two hundred miles of track in and around Boston, began to equip its lines in 1888 with the Thomson-Houston plant. The success of this great undertaking left no doubt of the future of electric traction. The difficulties which had seriously threatened future success were gradually removed."}]}
{"messages": [{"role": "assistant", "content": "The difficulties which had seriously threatened future success were gradually removed. The electric railway progress was so great in the United States that about January 1, 1891, there were more than two hundred and forty lines in operation. About thirty thousand horses and mules were replaced by electric power in the single year of 1891. In 1892 the Thomson-Houston interests and those of the Edison General Electric Company were merged in the General Electric Company, an event of unusual importance, as it brought together the two great competitors in electric traction at that date. Other electric manufacturers, chief among which was the Westinghouse Company, also entered the field and became prominent factors in railway extension. In a few years horse traction in the United States on tramway lines virtually disappeared."}]}
{"messages": [{"role": "assistant", "content": "In a few years horse traction in the United States on tramway lines virtually disappeared. Many cable lines were converted to electric lines, and projects such as the Boston Subway began to be planned. Not the least of the advantages of electric traction is the higher speed attainable with safety. The comfort and cleanliness of the cars, lighted brilliantly at night, and heated in winter by the same source of energy which is used to propel them, are important factors. All these things, together with the great extension of the lines into suburban and country districts, and the interconnection of the lines of one district with those of another, cannot fail to have a decidedly beneficial effect upon the life, habits, and health of the people. While the United States and Canada have been and still are the theatre of the enormous advance in electric traction, as in other electric work, many electric car lines have in recent years been established in Great Britain and on the continent of Europe."}]}
{"messages": [{"role": "assistant", "content": "While the United States and Canada have been and still are the theatre of the enormous advance in electric traction, as in other electric work, many electric car lines have in recent years been established in Great Britain and on the continent of Europe. Countries like Japan, Australia, South Africa, and South America have also in operation many electric trolley lines, and the work is rapidly extending. Most of this work, even in Europe, has been carried out either by importation of equipment from America, or by apparatus manufactured there, but following American practice closely. The bulk of the work has been done with the overhead wire and under-running trolley, but there are notable instances of the use of electric conductors in underground slotted conduits, chief of which are the great systems of street railway in New York City. In Chicago the application of motor-cars in trains upon the elevated railway followed directly upon the practical demonstration at the World’s Fair of the capabilities of third-rail electric traction on the Intramural Elevated Railway, and the system is rapidly extending so as to include all elevated city roads. A few years will doubtless see the great change accomplished."}]}
{"messages": [{"role": "assistant", "content": "A few years will doubtless see the great change accomplished. The motor-car, or car propelled by its own motors, has also been introduced upon standard steam roads to a limited extent as a supplement to steam traction. The earliest of these installations are the one at Nantasket, Massachusetts, and that between Hartford and New Britain, in Connecticut. A number of special high-speed lines, using similar plans, have gone into operation in recent years. The problem of constructing electric motors of sufficient robustness for heavy work and controlling them effectively was not an easy one, and the difficulties were increased greatly because of the placing of the motors under the car body, exposed to wet, to dust and dirt of road. The advantage of the motor-car, or motor-car train, is that the traction or hold upon the track increases with the increase of the weight or load carried."}]}
{"messages": [{"role": "assistant", "content": "The advantage of the motor-car, or motor-car train, is that the traction or hold upon the track increases with the increase of the weight or load carried. It is thus able to be accelerated rapidly after a stop, and also climb steep grades without slipping its wheels. Nevertheless, there are circumstances which favor the employment of a locomotive at the head of a train, as in steam practice. This is the case in lines where a train of coal or ore cars is drawn by electric mining locomotives. Many such plants are in operation, and, at the same time the electric power is used to drive fans for ventilating, pumps for drainage, electric hoists, etc., besides being used for lighting the mines. The trains in the tunnels of the Metropolitan Underground Railway of London have for many years been operated by steam locomotives with the inevitable escape of steam, foul, suffocating gases, and more or less soot."}]}
{"messages": [{"role": "assistant", "content": "The trains in the tunnels of the Metropolitan Underground Railway of London have for many years been operated by steam locomotives with the inevitable escape of steam, foul, suffocating gases, and more or less soot. A number of years ago the tunnel of the City and South London Railway was put into successful operation with electric locomotives drawing the trains of cars, and the nuisance caused by steam avoided. This work recalls the early efforts of Field, of Daft, and Bentley and Knight in providing an electric locomotive for replacing the steam plant of the elevated roads in New York City. Well-conceived as many of these plans were, electric traction had not reached a sufficient development, and the efforts were abandoned after several more or less successful trials. It is now seen that the motor-car train may advantageously replace the locomotive-drawn train in such instances as these elevated railways. The three largest and most powerful electric locomotives ever put into service are those which are employed to take trains through the Baltimore and Ohio Railroad tunnel at Baltimore."}]}
{"messages": [{"role": "assistant", "content": "The three largest and most powerful electric locomotives ever put into service are those which are employed to take trains through the Baltimore and Ohio Railroad tunnel at Baltimore. They have been in service about seven or eight years, and are fully equal in power to the large steam locomotives used on steam roads. Frequently trains of cars, including the steam locomotive itself, are drawn through the tunnel by these huge electric engines, the fires on the steam machines being for the time checked so as to prevent fouling the air of the tunnel. There was opened, in London, in 1900, a new railway called the Central Underground, equipped with twenty-six electric locomotives for drawing its trains. The electric and power equipment, which embodied in itself the latest results of American practice, was also manufactured in America to suit the needs of the road. Other similar railways are in contemplation in London and in other cities of Europe."}]}
{"messages": [{"role": "assistant", "content": "Other similar railways are in contemplation in London and in other cities of Europe. As on the elevated roads in New York City, the replacement of underground steam traction, where it exists, by electric traction is evidently only a question of a few years. An electric railway may exemplify a power-transmission system in which power is delivered to moving vehicles. But the distances so covered are not generally more than a few miles from the generating station. Where, however, abundant water-power exists, as at Niagara, or where fuel is very expensive and power is to be had only at great distances from the place at which it is to be used, electricity furnishes the most effective means for transmission and distribution. Between the years 1880 and 1890 the device called alternating current transformer was developed to a considerable degree of perfection."}]}
{"messages": [{"role": "assistant", "content": "Between the years 1880 and 1890 the device called alternating current transformer was developed to a considerable degree of perfection. It is, in reality, a modified induction coil, consisting of copper wire and iron, whereby a current sent through one of its coils will induce similar currents in the other coils of apparatus. It has the great advantage of having no moving parts. Faraday, in 1831, discovered the fundamental principle of the modern transformer. Not only, however, will the current in one coil of the apparatus generate by induction a new current in an entirely separate coil or circuit, but by suitably proportioning the windings we may exchange, as it were, a large low-pressure current for a small but high-pressure current, or _vice versa_. This exchange may be made with a very small percentage of loss of energy."}]}
{"messages": [{"role": "assistant", "content": "This exchange may be made with a very small percentage of loss of energy. These valuable properties of the transformer have rendered it of supreme importance in recent electrical extension. The first use made of it, in 1885–86, was to transform a high-pressure current into one of low pressure in electric lighting, enabling a small wire to be used to convey electric energy at high pressure, and without much loss, to a long distance from the station. This energy at high pressure reaches the transformer placed within or close to the building to be lighted. A low-pressure safe current is conveyed from the transformer to the wires connected to the lamps. In this way a current of two thousand volts, an unsafe and unsuitable pressure for incandescent lighting, is exchanged for one of about one hundred volts, which is quite safe."}]}
{"messages": [{"role": "assistant", "content": "In this way a current of two thousand volts, an unsafe and unsuitable pressure for incandescent lighting, is exchanged for one of about one hundred volts, which is quite safe. In this way, also, the supply station is enabled to reach a customer too far away to be supplied directly with current at one hundred volts, without enormous expense for copper conductors. The alternating current transformer not only greatly extended the radius of supply from a single station, but also enabled the station to be conveniently located where water and coal could be had without difficulty. It also permitted the distant water-powers to become sources of electric energy for lighting, power, or for other service. For example, a water-power located at a distance of fifty to one hundred miles or more from a city, or from a large manufacturing centre where cost of fuel is high, may be utilized as follows: A power-station will be located upon the site of the water-power, and the dynamos therein will generate electricity at, say, two thousand volts pressure. By means of step-up transformers this will be exchanged for a current of thirty thousand volts for transmission over a line of copper or aluminum wire to the distant consumption area."}]}
{"messages": [{"role": "assistant", "content": "By means of step-up transformers this will be exchanged for a current of thirty thousand volts for transmission over a line of copper or aluminum wire to the distant consumption area. Here there will be a set of step-down transformers which will exchange the thirty-thousand-volt line current for one of so low a pressure as to be safe for local distribution to lamps, to motors, etc., either stationary or upon a railway. The same transmission plant may simultaneously supply energy for lighting, for power, for heat, and for charging storage batteries. It may, therefore, be employed both day and night. These long-distance power transmission plants are generally spoken of as “two-phase,” “three-phase,” or “polyphase” systems. Before 1890 no such plants existed."}]}
{"messages": [{"role": "assistant", "content": "Before 1890 no such plants existed. A large number of such installations are now working over distances of a few miles up to one hundred miles. They differ from what are known as single-phase alternating systems in employing, instead of a single alternating current, two, three, or more, which are sent over separate lines, and in which the electric impulses are not simultaneous, but follow each other in regular succession, overlapping each other’s dead points, so to speak. Early suggestions of such a plan, about 1880, and thereafter, by Bailey, Deprez, and others, bore no fruit, and not until Tesla’s announcement of his polyphase system, in 1888, was much attention given to the subject. A widespread interest in Tesla’s work was invoked, but several years elapsed before engineering difficulties were overcome. This work was done mainly by the technical staffs of the large manufacturing companies, and it was necessary to be done before any notable power transmissions on the polyphase system could be established."}]}
{"messages": [{"role": "assistant", "content": "This work was done mainly by the technical staffs of the large manufacturing companies, and it was necessary to be done before any notable power transmissions on the polyphase system could be established. After 1892 the growth became very rapid. The falls of Niagara early attracted the attention of engineers to the possibility of utilizing at least a fraction of the power. It was seen that several hundred thousand horse-power might be drawn from it without materially affecting the fall, itself equivalent to several millions of horse-power. A gigantic power-station has lately been established at Niagara, taking water from a distance above the falls and delivering it below the falls through a long tunnel which forms the tail race. Ten water-wheels, located in an immense wheel-pit about two hundred feet deep, each wheel of a capacity of five thousand horse-power, drive large vertical shafts, at the upper end of which are located the large two-phase dynamos, each of five thousand horse-power."}]}
{"messages": [{"role": "assistant", "content": "Ten water-wheels, located in an immense wheel-pit about two hundred feet deep, each wheel of a capacity of five thousand horse-power, drive large vertical shafts, at the upper end of which are located the large two-phase dynamos, each of five thousand horse-power. The electric energy from these machines is in part raised in pressure by huge transformers for transmission to distant points, such as the city of Buffalo, and a large portion is delivered to the numerous manufacturing plants located at moderate distances from the power-station. Besides the supply of energy for lighting, and for motors, including railways, other recent uses of electricity to which we have not yet alluded are splendidly exemplified at Niagara. Davy’s brilliant discovery of the alkali metals, sodium and potassium, at the opening of the century, showed the great chemical energy of the electric current. Its actions were afterwards carefully studied, notably by the illustrious Faraday, whose discoveries in connection with magnetism and magneto-electricity have been briefly described. The electric current was found to act as a most potent chemical force, decomposing and recomposing many chemical compounds, dissolving and depositing metals."}]}
{"messages": [{"role": "assistant", "content": "The electric current was found to act as a most potent chemical force, decomposing and recomposing many chemical compounds, dissolving and depositing metals. Hence, early in the century arose the art of electroplating of metals, such as electro-gilding, silver-plating, nickel-plating, and copper deposition as in electrotyping. These arts are now practised on a very large scale, and naturally have affected the whole course of manufacturing methods during the century. Moreover, since the introduction of dynamo current, electrolysis has come to be employed in huge plants, not only for separating metals from each other, as in refining them, but in addition for separating them from their ores, for the manufacture of chemical compounds before unknown, and for the cheap production of numerous substances of use in the various arts on a large scale. Vast quantities of copper are refined, and silver and gold often obtained from residues in sufficient amount to pay well for the process. At Niagara also are works for the production of the metal aluminum from its ores."}]}
{"messages": [{"role": "assistant", "content": "At Niagara also are works for the production of the metal aluminum from its ores. Similar works exist at other places here and abroad where power is cheap. This metal, which competes in price with brass, bulk for bulk, was only obtainable before its electric reduction at $25 to $30 per pound. The metal sodium is also extracted from soda. A large plant at Niagara also uses the electric current for the manufacture of chlorine for bleach, and caustic soda, both from common salt. Chlorate of potassium is also made at Niagara by electrolysis."}]}
{"messages": [{"role": "assistant", "content": "Chlorate of potassium is also made at Niagara by electrolysis. The field of electro-chemistry is, indeed, full of great future possibilities. Large furnaces heated by electricity, a single one of which will consume more than a thousand horse-power, exist at Niagara. In these furnaces is manufactured from coke and sand, by the Acheson process, an abrasive material called carborundum, which is almost as hard as diamond, but quite low in cost. It is made into slabs and into wheels for grinding hard substances. The electric furnace furnishes also the means for producing artificial plumbago, or graphite, almost perfectly pure, the raw material being coke powder."}]}
{"messages": [{"role": "assistant", "content": "The electric furnace furnishes also the means for producing artificial plumbago, or graphite, almost perfectly pure, the raw material being coke powder. A large amount of power from Niagara is also consumed for the production in special electric arc furnaces of carbide of calcium from coke and lime. This is the source of acetylene gas, the new illuminant, which is generated when water is brought into contact with the carbide. The high temperature of the electric furnace thus renders possible chemical actions which under ordinary furnace heat would not take place. Henri Moissan, a French scientist, well known for his brilliant researches in electric furnace work, has even shown that real diamonds can be made under special conditions in the electric furnace. He has, in fact, probably practised in a small way what has occurred on a grand scale in nature, resulting in diamond fields such as those at Kimberley."}]}
{"messages": [{"role": "assistant", "content": "He has, in fact, probably practised in a small way what has occurred on a grand scale in nature, resulting in diamond fields such as those at Kimberley. One problem less is thus left to be solved. The electro-chemical and kindred arts are practised not alone at Niagara, but at many other places where power is cheap. Extensive plants have grown up, mostly within the five years before the close of the century. All of the great developments in this field have come about within the last decade. The use of electricity for heating is not confined to electric furnaces, in which the exceedingly high temperature obtainable is the factor giving rise to success."}]}
{"messages": [{"role": "assistant", "content": "The use of electricity for heating is not confined to electric furnaces, in which the exceedingly high temperature obtainable is the factor giving rise to success. While it is not likely that electricity will soon be used for general heating, special instances, such as the warming of electric cars in winter by electric heaters, the operation of cooking appliances by electric current, the heating of sad-irons and the like, give evidence of the possibilities should there ever be found means for the generation of electric energy from fuel with such high efficiency as eighty per cent. or more. Present methods give, under most favorable conditions, barely ten per cent., ninety per cent. of the energy value of the fuel being unavoidably wasted. Another application of the heating power of electric currents is found in the Thomson electric welding process, the development of which has practically taken place in the past ten years."}]}
{"messages": [{"role": "assistant", "content": "Another application of the heating power of electric currents is found in the Thomson electric welding process, the development of which has practically taken place in the past ten years. In this process an exceedingly large current, at very low electric pressure, traverses a joint between two pieces of metal to be united. It heats the joint to fusion or softening; the pieces are pushed together and welded. Here the heat is generated in the solid metal, for at no time during the operation are the pieces separated. The current is usually obtained from a welding transformer, an example of an extreme type of step-down transformer. Current at several hundred volts passed into the primary winding is exchanged for an enormous current at only two or three volts in the welding circuit in which the work is done."}]}
{"messages": [{"role": "assistant", "content": "Current at several hundred volts passed into the primary winding is exchanged for an enormous current at only two or three volts in the welding circuit in which the work is done. The present uses of this electric welding process are numerous and varied. Pieces of most of the metals and alloys, before regarded as unweldable, are capable of being joined not only to pieces of the same metal, but also to different metals. Electric welding is applied on the large scale, making joints in wires or rods, for welding wagon and carriage wheel tires, for making barrel-hoops and bands for pails, for axles of vehicles, and for carriage framing. It has given rise to special manufactures, such as electrically welded steel pipe or tube, wire fencing, etc. It is used for welding together the joints of steel car-rails, for welding teeth in saws, for making many parts of bicycles, and in tool making."}]}
{"messages": [{"role": "assistant", "content": "It is used for welding together the joints of steel car-rails, for welding teeth in saws, for making many parts of bicycles, and in tool making. An instance of its peculiar adaptability to unusual conditions is the welding of the iron bands embedded within the body of a rubber vehicle tire for holding the tire in place. For this purpose the electric weld has been found almost essential. Another branch of electric development concerns the storage of electricity. The storage battery is based upon principles discovered by Gaston Planté, and applied, since 1881, by Brush, by Faure, and others. Some of the larger lighting stations employ as reservoirs of electric energy large batteries charged by surplus dynamo current."}]}
{"messages": [{"role": "assistant", "content": "Some of the larger lighting stations employ as reservoirs of electric energy large batteries charged by surplus dynamo current. This is afterwards drawn upon when the consumer’s load is heavy, as during the evening. The storage battery is, however, a heavy, cumbrous apparatus, of limited life, easily destroyed unless guarded with skill. If a form not possessing these faults be ever found, the field of possible application is almost limitless. The above by no means complete account of the progress in electric applications during the century just closed should properly be supplemented by an account of the accompanying great advances regarded from the purely scientific aspect. It is, however, only possible to make a brief reference thereto within the limits of this article."}]}
{"messages": [{"role": "assistant", "content": "It is, however, only possible to make a brief reference thereto within the limits of this article. The scientific study of electricity and the application of mathematical methods in its treatment has kept busy a host of workers and drawn upon the resources of the ablest minds the age has produced. Gauss, Weber, Ampère, Faraday, Maxwell, Helmholtz, are no longer with us. Of the early founders of the science we have yet such men as Lord Kelvin, formerly Sir William Thomson, Mascart, and others, still zealous in scientific work. Following them are a large number, notable for valuable contributions to the progress of electrical science, in discoveries, in research, and in mathematical treatment of the various problems presented. Modern magnetism took form in the hands of Rowland, Hopkinson, Ewing, and many other able workers."}]}
{"messages": [{"role": "assistant", "content": "Modern magnetism took form in the hands of Rowland, Hopkinson, Ewing, and many other able workers. Maxwell’s electro-magnetic theory of light is confirmed by the brilliant researches of the late Dr. Hertz, too early lost to science. Hertz proved that all luminous phenomena are in essence electrical. The wireless telegraphy of to-day is a direct outcome of Hertz’s experiments on electric waves. It is but little more than ten years since Hertz announced his results to the world."}]}
{"messages": [{"role": "assistant", "content": "It is but little more than ten years since Hertz announced his results to the world. His work, supplemented by that of Branly, Lodge, Marconi, and others, made wireless telegraphy a possibility. The wonderful X-ray, and the rich scientific harvest which has followed the discovery by Röntgen of invisible radiation from a vacuum tube, was preceded by much investigation of the effects of electric discharges in vacuum tubes, and Hittorf, followed by Crookes, had given special study to these effects in very high or nearly perfect vacua. Crookes, though especially enriching science by his work, missed the peculiar X-ray, which, nevertheless, must have been emitted from many of his vacuum tubes, not only in his hands, but in those of subsequent students. It was as late as 1896 that Röntgen announced his discovery. Since that time several other sources of invisible radiation have been discovered, more or less similar in effect to the radiations from a vacuum tube, but emitted, singular as the fact is, from rare substances extracted from certain minerals."}]}
{"messages": [{"role": "assistant", "content": "Since that time several other sources of invisible radiation have been discovered, more or less similar in effect to the radiations from a vacuum tube, but emitted, singular as the fact is, from rare substances extracted from certain minerals. Leaving out of consideration the great value of the X-ray to physicians and surgeons, its effect in stimulating scientific inquiry has almost been incalculable. The renewed study of effects of electric discharge in vacuum tubes has already, in the work of such investigators as Lenard, J. J. Thomson, and others, apparently carried the subdivision of matter far beyond the time-honored chemical atom, and has gone far towards showing the essential unity of all the chemical elements. It is as unlikely that the mystery of the material universe will ever be completely solved as it is that we can gain an adequate conception of infinite space or time."}]}
{"messages": [{"role": "assistant", "content": "It is as unlikely that the mystery of the material universe will ever be completely solved as it is that we can gain an adequate conception of infinite space or time. But we can at least extend the range of our mental vision of the processes of nature as we do our real vision into space depths by the telescope and spectroscope. There can now be no question that electric conditions and actions are more fundamental than many hitherto so regarded. The nineteenth century closed with many important problems in electrical science unsolved. What great or far-reaching discoveries are yet in store, who can tell? What valuable practical developments are to come, who can predict?"}]}
{"messages": [{"role": "assistant", "content": "What valuable practical developments are to come, who can predict? The electrical progress has been great—very great—but after all only a part of that grander advance in so many other fields. The hands of man are strengthened by the control of mighty forces. His electric lines traverse the mountain passes as well as the plains. His electric railway scales the Jungfrau. But he still spends his best effort, and has always done so, in the construction and equipment of his engines of destruction, and now exhausts the mines of the world of valuable metals, for ships of war, whose ultimate goal is the bottom of the sea."}]}
{"messages": [{"role": "assistant", "content": "But he still spends his best effort, and has always done so, in the construction and equipment of his engines of destruction, and now exhausts the mines of the world of valuable metals, for ships of war, whose ultimate goal is the bottom of the sea. In this also electricity is made to play an increasingly important part. It trains the guns, loads them, fires them. It works the signals and the search-lights. It ventilates the ship, blows the fires, and lights the dark spaces. Perhaps all this is necessary now, and, if so, well."}]}
{"messages": [{"role": "assistant", "content": "Perhaps all this is necessary now, and, if so, well. But if a fraction of the vast expenditure entailed were turned to the encouragement of advance in the arts and employments of peace in the twentieth century, can it be doubted that, at the close, the nineteenth century might come to be regarded, in spite of its achievements, as a rather wasteful, semi-barbarous transition period? ELIHU THOMSON. PHYSICS \n\nOn January 7, 1610, Galileo, turning his telescope towards Jupiter, was the first to see the beautiful system of that planet in which the universe is epitomized. He had already studied the variegated surface of the moon, and he had seen the spots upon the sun. A little later, in spite of the feeble power of his instrument, he had discovered that the sun rotates upon an axis, and something of the wonderful nature of the planet Saturn had been revealed to him."}]}
{"messages": [{"role": "assistant", "content": "A little later, in spite of the feeble power of his instrument, he had discovered that the sun rotates upon an axis, and something of the wonderful nature of the planet Saturn had been revealed to him. The overwhelming evidence thus afforded of the truth of the hypothesis of Copernicus made him its chief exponent. The time had come for man to know, as he had never known or even dreamed before, his true relation to the universe of which he was so insignificant a part. In a single year nearly all of these capital discoveries were made. It was truly an era of intellectual expansion; never before and never since has man’s intellectual horizon enlarged with such enormous rapidity. One needs little imagination to share with this ardent philosopher the enthusiasm of the moment when, because some, fearing the evidence of their senses, refused to look through the slender tube, he wrote to Kepler: “Oh, my dear Kepler, how I wish we could have one hearty laugh together!..."}]}
{"messages": [{"role": "assistant", "content": "One needs little imagination to share with this ardent philosopher the enthusiasm of the moment when, because some, fearing the evidence of their senses, refused to look through the slender tube, he wrote to Kepler: “Oh, my dear Kepler, how I wish we could have one hearty laugh together!... Why are you not here? What shouts of laughter we should have at this glorious folly!” \nGalileo died in 1642, and in the same year Newton was born. When twenty-four years old he “began to think of gravity extending to the orb of the moon,” and before the end of the century he had discovered and established the great law of universal gravitation. Thus, at the end of the seventeenth century, the foundations of modern physics were in place. During the eighteenth century they were much built upon, but it was the nineteenth that witnessed not only the greatest advance in detail, but the most important generalizations made since the time of Galileo and Newton."}]}
{"messages": [{"role": "assistant", "content": "During the eighteenth century they were much built upon, but it was the nineteenth that witnessed not only the greatest advance in detail, but the most important generalizations made since the time of Galileo and Newton. In endeavoring to present to the intelligent but perhaps unscientific reader a brief review of the accomplishments of that “wonderful century” in the domain of physics, one must not attempt more than an outline of greater events, and it will be convenient to arrange them under the several principal subdivisions of the science, according to the usually accepted classification. HEAT \nAlthough more than one philosopher of the seventeenth and eighteenth centuries suggested the identity of heat and molecular motion, the impression made was not lasting, and up to very near the beginning of the nineteenth century the _caloric_ theory was accepted almost without dispute. This theory implied that heat was a subtle fluid, definite quantities of which were added to or subtracted from material substances when they became hot or cold. As carefully conducted experiments seemed to show that a body weighed no more or no less when hot than when cold, it was necessary to attribute to this fluid called caloric the mysterious property of imponderability, that is, unlike all forms of ordinary matter, it possessed no weight. To avoid calling it matter, it was by many classed with light, electricity, and magnetism, as one of the _imponderable agents_."}]}
{"messages": [{"role": "assistant", "content": "To avoid calling it matter, it was by many classed with light, electricity, and magnetism, as one of the _imponderable agents_. Various other properties were attributed to caloric, necessary to the reasonable explanation of a steadily increasing array of experimental facts. It was declared to be elastic, its particles being mutually self-repellent. It was thought to attract ordinary matter, and an ingenious theory of caloric was constructed, modelled upon Newton’s famous but erroneous corpuscular theory of light. During the latter part of the eighteenth century Joseph Black, professor in the Universities of Glasgow and Edinburgh, developed his theory of _latent heat_, which, although founded upon a false notion of the nature of heat, was a most important contribution to science. The downfall of the caloric theory must be largely credited to the work of a famous American who published the results of his experiments just at the close of the eighteenth century."}]}
{"messages": [{"role": "assistant", "content": "The downfall of the caloric theory must be largely credited to the work of a famous American who published the results of his experiments just at the close of the eighteenth century. Benjamin Thompson, generally known as Count Rumford, was born in the town of Woburn, Massachusetts, in 1753. His inclination towards physical experimentation was strong in his early youth, and he received much instruction and inspiration from the lectures of Professor John Winthrop, of Harvard College, some of which he was enabled to attend under trying conditions. Having received special official consideration by appointment to office under one of the colonial governors, he was accused at the breaking out of the Revolutionary War of a leaning towards Toryism, and was thus prevented from making his career among his own people. At the age of twenty-two years he fled to England, returning to America only for a brief period in command of a British regiment. In England he soon became eminent as an experimental philosopher, and in 1778 became a Fellow of the Royal Society."}]}
{"messages": [{"role": "assistant", "content": "In England he soon became eminent as an experimental philosopher, and in 1778 became a Fellow of the Royal Society. He afterwards entered the service of the Elector of Bavaria, by whom he was made a Count of the Holy Roman Empire. In 1799 he returned to London and founded the “Royal Institution,” which was destined during the next hundred years to surpass all other foundations in the richness and importance of its contributions to physical science. It was while at Munich that Rumford made his famous experiments on the nature of heat, to which he had been led by observing the great amount of heat generated in the boring of cannon. Finding that he was able to make a considerable quantity of water actually boil by the heat generated by a blunt boring tool, he concluded that the supply of heat from such a source was practically inexhaustible and that it could be generated continuously if only the motion of the tool under friction was kept up. He declared that anything which could thus be produced without limitation by an insulated body or system of bodies could not possibly be a material substance, and that under the circumstances of the experiment, the only thing that was or could be thus continuously communicated was _motion_."}]}
{"messages": [{"role": "assistant", "content": "He declared that anything which could thus be produced without limitation by an insulated body or system of bodies could not possibly be a material substance, and that under the circumstances of the experiment, the only thing that was or could be thus continuously communicated was _motion_. Count Rumford’s conclusions were not for a long time accepted. Davy, the brilliant professor and eloquent lecturer at the newly established Royal Institution, espoused the mechanical theory of heat and made the striking experiment of melting two pieces of ice by rubbing them together remote from any source of heat. His contemporary, Thomas Young, who overturned Newton’s corpuscular theory of light and showed that it was a wave phenomenon, also advocated Rumford’s notion of the nature of heat, but even among physicists of high rank it had made little headway as late as the middle of the nineteenth century. In the eighth edition of the Encyclopædia Britannica, published in 1856, the immediate predecessor of the current issue, heat is defined as “a material agent of a peculiar nature, highly attenuated.” And this, in spite of the fact that previous to that date the mechanical theory had been completely proved by the labors of Mayer, Joule, Helmholtz, and William Thomson (Lord Kelvin). By these men a solid foundation for the theory had been found in a great physical law of such importance that it is justly considered to be the most far-reaching generalization in natural philosophy since the time of Newton."}]}
{"messages": [{"role": "assistant", "content": "By these men a solid foundation for the theory had been found in a great physical law of such importance that it is justly considered to be the most far-reaching generalization in natural philosophy since the time of Newton. Some account of this law and its discovery will be given later in this paper. Among the most important of the century’s contributions to our knowledge of heat must be included the work of Fourier, as embodied in his _Theorie Analytique de la Chaleur_, published in 1822. Joseph Fourier was born in 1768, and died in 1830. He belonged to that splendid group of philosophers of which the French nation may always be proud, whose work constitutes a large part of the lustre of intellectual France during her most brilliant period, the later years of the eighteenth and the earlier years of the nineteenth century. His contemporaries included such men as Laplace, Arago, Lagrange, Fresnel, and Carnot."}]}
{"messages": [{"role": "assistant", "content": "His contemporaries included such men as Laplace, Arago, Lagrange, Fresnel, and Carnot. Fourier wrote especially of the movement of heat in solids, and as his thesis depended in no way on the nature of heat it will always be regarded as a classic. His assumption that conductivity was independent of temperature was shortly proved to be erroneous, but his general argument and conclusions were not greatly affected by this discovery. His work is one of the most beautiful examples yet produced of the application of mathematics to physical research, and mathematical and physical science were equally enriched by it. In its broader aspects his law of conduction includes the transfer of electricity in good conductors, and is the real basis of Ohm’s law. One of the most skillful and successful experimenters in heat was also a Frenchman, Henri Victor Regnault (1810–78)."}]}
{"messages": [{"role": "assistant", "content": "One of the most skillful and successful experimenters in heat was also a Frenchman, Henri Victor Regnault (1810–78). He greatly improved the construction and use of the thermometer, and was the first to discover that the indications of an air thermometer and one of mercury did not exactly agree, because they did not expand in the same degree for equal increases of temperature. His most important work was on the expansion of gases, vapor pressure, specific heat of water, etc., and for careful, patient measuring he had a positive genius. Until he proved the contrary it had been assumed that all gases had the same coefficient of expansion, and Boyle’s law that the volume of a gas was inversely proportional to its pressure had not been questioned. His tables of the elastic force of steam have been of immense practical value, but his studies of the expansion of gases are of greater interest because they have pointed the way to one of the most important accomplishments of the century, the liquefaction of all known gases. During the earlier years of this century it was the custom to consider vapors and gases as quite distinct forms of matter."}]}
{"messages": [{"role": "assistant", "content": "During the earlier years of this century it was the custom to consider vapors and gases as quite distinct forms of matter. Vapors always came, by evaporation, from liquids, and could always be “condensed” or reduced to the liquid form without difficulty, but it was not thought possible to liquefy the so-called “permanent” gases. The first man to attack the problem systematically was Michael Faraday, who, before the end of the first third of the century, had liquefied several gases, mostly by producing them by chemical reactions under pressure. Several of the more easily reducible gases or vapors, such as ammonia, sulphurous acid, and probably chlorine, had been previously liquefied by cold, but a quarter of a century elapsed after Faraday’s researches before the true relation of the liquid and gaseous states of matter was understood, and it was found that both increase of pressure and lowering of temperature were, in general, essential to the liquefaction of a gas. It was Thomas Andrews, of Belfast, who first showed, in a paper published in 1863, that there was a continuity in the liquid and gaseous states of matter, that for each substance there was a critical temperature at which it became a homogeneous fluid, neither a liquid nor a gas: that above this temperature great pressure would not liquefy, while below it the substance might exist as partly liquid and partly gas. He pointed out the fact that for the so-called permanent gases this critical temperature must be exceedingly low, and if such temperature could be reached liquefaction would follow."}]}
{"messages": [{"role": "assistant", "content": "He pointed out the fact that for the so-called permanent gases this critical temperature must be exceedingly low, and if such temperature could be reached liquefaction would follow. Subsequent progress in the liquefaction of gases came about by following this suggestion. Very low temperatures were produced by subjecting the gas to great reduction in volume by pressure, removing the heat of compression by conduction and radiation, and then by sudden expansion its temperature was greatly lowered. As early as 1877 two Frenchmen, Pictet and Cailletet, had succeeded in liquefying oxygen, hydrogen, nitrogen, and air. During the past twenty years great improvements have been made in the methods of accomplishing these transformations, so that to-day it is easy to produce considerable quantities of all of the principal gases in a liquid form, and by carrying the reduction in temperature still further portions of the liquid may be changed to the solid state. The most important work along this line has been done by Wroblewski and Olszewski, of the University of Cracow, and Professor Dewar, of the Royal Institution in London."}]}
{"messages": [{"role": "assistant", "content": "The most important work along this line has been done by Wroblewski and Olszewski, of the University of Cracow, and Professor Dewar, of the Royal Institution in London. Temperatures as low as about two hundred and fifty degrees C. below the freezing-point of water have been produced, the “absolute zero” being only two hundred and seventy-three degrees C. below that point. These experiments promise to throw much light on the nature of matter, and they are especially interesting as revealing its extraordinary properties at extremely low temperatures. Among the most curious and suggestive is the fact that the electrical resistance of pure metals diminishes at a rate which indicates that at the absolute zero it would vanish, and these metals would become perfect conductors of electricity."}]}
{"messages": [{"role": "assistant", "content": "Among the most curious and suggestive is the fact that the electrical resistance of pure metals diminishes at a rate which indicates that at the absolute zero it would vanish, and these metals would become perfect conductors of electricity. The dynamics of heat, or “thermo-dynamics,” was an important field of research in the early part of the century, on account of its practical application to the improvement of the steam-engine. The science was created by Carnot, who, in spite of the fact that his views regarding the nature of heat were erroneous, discovered some of the most interesting relations among the quantities involved, and discussed their applications to the heat engines with great skill. Subsequent contributors to the theory and practice of thermo-dynamics were Clausius, Rankine, Lord Kelvin, and Professor Tait. The mechanical theory of heat naturally led up to what has already been referred to as the most important generalization in physical science since the time of Newton, the doctrine of \n\nTHE CONSERVATION OF ENERGY \nThis principle puts physics in its relation to energy where chemistry has long been in its relation to matter. If matter were not conservative, if it could be created or destroyed at will, chemistry would be an impossible science."}]}
{"messages": [{"role": "assistant", "content": "If matter were not conservative, if it could be created or destroyed at will, chemistry would be an impossible science. Physics is put upon a solid foundation by the assumption of a like conservatism in energy; it can neither be created nor destroyed, although it may appear in many different forms which are, in general, mutually interconvertible. Many men have contributed to the establishment of this great principle, but it was actually discovered and proved by the labors of three or four. Although it was practically all done before the middle of the nineteenth century, its general popular recognition did not come until a quarter of a century later. The doctrine was first distinctly formulated by Robert Mayer, a German physician, who published in 1842 a suggestive paper on “The Forces of Inorganic Nature,” which, however, attracted little or no attention. Mayer had not approached the problem from an experimental stand-point, but at about the same time it was attacked most successfully from this side by a young Englishman, James Prescott Joule, son of a wealthy brewer of Manchester, England."}]}
{"messages": [{"role": "assistant", "content": "Mayer had not approached the problem from an experimental stand-point, but at about the same time it was attacked most successfully from this side by a young Englishman, James Prescott Joule, son of a wealthy brewer of Manchester, England. Joule made the first really accurate determination of the mechanical equivalent of a given quantity of heat, a physical constant which Rumford had tried to measure, reaching only a rough approximation. Substantially Joule’s result was that the heat energy necessary to raise the temperature of any given mass of water one degree Fahr. is the equivalent of the mechanical energy required to lift that mass through a height of seven hundred and seventy-two feet against the force of the earth’s attraction; and, conversely, if a mass of water be allowed to fall through a distance of seven hundred and seventy-two feet under the action of gravity, and at the end of its motion be instantly arrested, the heat generated will suffice to raise its temperature one degree Fahr. Of such vast importance is this numerical coefficient that it has been called the golden number of the nineteenth century. Since Joule’s time it has been redetermined by several physicists, notably by Professor Rowland, of Baltimore, the general conclusion being that Joule’s number was somewhat, but not greatly, too small."}]}
{"messages": [{"role": "assistant", "content": "Since Joule’s time it has been redetermined by several physicists, notably by Professor Rowland, of Baltimore, the general conclusion being that Joule’s number was somewhat, but not greatly, too small. The first clear and full exposition of the doctrine of the conservation of energy was given by Joule in a popular lecture in Manchester in 1847, but it attracted little attention until a few months later, when the author presented his theory at a meeting of the British Association for the Advancement of Science. Even among scientific men it would have passed without comment or consideration had it not been for the presence of another young Englishman, then as little known as Joule himself, who began a series of remarks, appreciative and critical, which resulted in making Joule’s paper the sensation of the meeting. This was William Thomson, who had been, only a year before, at the age of twenty-two years, appointed professor of natural philosophy at the University of Glasgow, now known as Lord Kelvin, the most versatile, brilliant, and profound student of physical science which the century has produced. From that day to the death of Joule (1889) these two men were closely associated in the demonstration and exploitation of a great principle of which they were at first almost the sole exponents among English-speaking people. By an interesting coincidence, in the same year in which Joule announced the result of his experiments, the Physical Society of Berlin listened to a paper almost identical with Joule’s in character and conclusions, but prepared quite independently, by a young German physician, Herman von Helmholtz, destined to rank at the time of his death, in 1893, as one of the very first mathematicians of the age, doubtless the first physiologist of his time, and as a physicist with whom not more than one other of the nineteenth century may be compared."}]}
{"messages": [{"role": "assistant", "content": "By an interesting coincidence, in the same year in which Joule announced the result of his experiments, the Physical Society of Berlin listened to a paper almost identical with Joule’s in character and conclusions, but prepared quite independently, by a young German physician, Herman von Helmholtz, destined to rank at the time of his death, in 1893, as one of the very first mathematicians of the age, doubtless the first physiologist of his time, and as a physicist with whom not more than one other of the nineteenth century may be compared. Helmholtz’s paper was rejected by the editor of the leading scientific journal of Germany, but his work was so important that he must always share with Joule and Kelvin in the glory of this epoch-making generalization. Even a brief sketch of the history of the doctrine of the conservation of energy would be incomplete if mention were not made of the work of Tyndall. Although by original research he contributed in no small degree to the demonstration of the theory, it is mainly through his wonderful skill in popular presentation of the principles of physical science that he becomes related to the great movement of the middle of the century. His masterful exposition of the new theory in a course of lectures at the Royal Institution, given in 1862 and published in 1863 under the title _Heat as a Mode of Motion_, was the means of making the intelligent public acquainted with its beauty and profound significance, and the history of science affords no more admirable example of the possibilities and wisdom of popular scientific writing than this book. As for the principle of the conservation of energy itself it is not too much to say that during the last half of the century it has been the guiding and controlling spirit of all scientific discovery or of invention through the application of scientific principles."}]}
{"messages": [{"role": "assistant", "content": "As for the principle of the conservation of energy itself it is not too much to say that during the last half of the century it has been the guiding and controlling spirit of all scientific discovery or of invention through the application of scientific principles. LIGHT \nThe revival and final establishment of the undulatory or wave theory of light is one of the glories of the nineteenth century, and the credit for it is due to Thomas Young, an Englishman, and Fresnel, a Frenchman. Newton had conceived, espoused, and, owing to the great authority of his name, almost fixed upon the learned world the corpuscular or emission theory, which assumes that all luminous bodies emit streams of minute corpuscles, which are reflected, refracted, and produce vision. Many ordinary optical phenomena were explained by this hypothesis only with great difficulty, and some were quite unexplainable. The transmission of a disturbance or vibratory motion by means of waves, as in the case of sound, was a well-recognized principle, and Young and Fresnel applied it most successfully to the phenomena of light. Wave motion, in a general way, is only possible in a sensibly continuous medium, such as water, air, etc., and the theory that light was a vibratory disturbance transmitted by means of waves necessitated the assumption of the existence of such a medium throughout all space in which light travelled."}]}
{"messages": [{"role": "assistant", "content": "Wave motion, in a general way, is only possible in a sensibly continuous medium, such as water, air, etc., and the theory that light was a vibratory disturbance transmitted by means of waves necessitated the assumption of the existence of such a medium throughout all space in which light travelled. What is known as the ethereal medium, at first a purely imaginary substance, but whose real existence is practically established, satisfies this demand, and the hypothesis that light is transmitted by waves in such a medium, originating in a vibratory disturbance at the source, has been of inestimable value to physical science. The work of Thomas Young was done in the very first years of the nineteenth century. He was for two years professor of Natural Philosophy in the Royal Institution just founded by Count Rumford, and he was the first to fill that chair. In 1801, in a paper presented to the Royal Society, he argued in favor of the undulatory theory, showing how the interference of waves would explain the color of thin plates. His papers were not, for several years, received favorably, and they were severely criticised by Lord Brougham."}]}
{"messages": [{"role": "assistant", "content": "His papers were not, for several years, received favorably, and they were severely criticised by Lord Brougham. Augustus Fresnel followed Young, but quite independently, about ten years later, and by him the undulatory theory received elaborate experimental and mathematical treatment. In the mean time another Frenchman had made a capital discovery in optics, which seemed at first to be quite incompatible with the wave theory. This was the discovery of what is known as _polarization of light_ by Malus, a French engineer, who hit upon it while investigating double refraction of crystals, for a study of which the French Institute had offered a prize in 1808. Malus found that when light fell upon a surface of glass at a certain angle a portion of the reflected light appeared to have acquired entirely new properties in regard to further reflection, and the same was true of that part of the beam which was transmitted through the glass. The light thus affected was incapable of further reflection under certain conditions, and as the beam seemed to behave differently according to how it was presented to the reflecting surface, the term polarization was applied to the phenomenon."}]}
{"messages": [{"role": "assistant", "content": "The light thus affected was incapable of further reflection under certain conditions, and as the beam seemed to behave differently according to how it was presented to the reflecting surface, the term polarization was applied to the phenomenon. It was found that the two rays into which a single beam of light was split by a doubly refracting crystal (a phenomenon which had long been known) were affected in this way, and that light was polarized by refraction as well as by reflection. Malus was a believer in the corpuscular theory of light, but it was shortly proved, first by Thomas Young, that the phenomenon of polarization was not only not opposed to the wave theory, but that that theory furnished a rational explanation of it. This explanation, in brief, assumes that ordinary light is a wave produced by a vibratory motion confined to no particular plane, the direction of vibration being at right angles to the direction of the wave, and in any, or, in rapid succession, in _all_ azimuths. When light is polarized the vibratory motion in the ether is restricted to one particular form, a line if plane polarized, a circle or an ellipse if circularly or elliptically polarized. This simple hypothesis has been found quite adequate, and through its application to the various phenomena of polarization, together with the application of Young’s theory of the interference of waves to the production of color, the undulatory theory of light was firmly established before the middle of the century."}]}
{"messages": [{"role": "assistant", "content": "This simple hypothesis has been found quite adequate, and through its application to the various phenomena of polarization, together with the application of Young’s theory of the interference of waves to the production of color, the undulatory theory of light was firmly established before the middle of the century. There were many noted philosophers, however, who stood out long against it, notably Brewster, the most famous English student of optics of the early part of the century, who declared that his “chief objection to the undulatory theory was that he could not think the Creator guilty of so clumsy a contrivance as the filling of space with ether in order to produce light.” In studying the nature of light it became very important to know how fast a light wave travelled. A tolerably good measure of the velocity of light had been made long before by means of the eclipses of Jupiter’s moons and by observations upon the positions of the stars as influenced by the motion of the earth in its orbit. It was found to be approximately one hundred and eighty thousand miles per second, a speed so great that it seemed impossible that it should ever be measured by using only terrestrial distances. This extremely difficult problem has been solved, however, in a most satisfactory manner by nineteenth-century physicists. Everybody knows that in a uniform motion velocity is equal to space or distance divided by time."}]}
{"messages": [{"role": "assistant", "content": "Everybody knows that in a uniform motion velocity is equal to space or distance divided by time. If, then, the time occupied in passing through a given distance can be measured, the velocity is at once known. As the velocity of light is very large, unless the distance is enormously great, the time will be extremely small, and if moderate distances are to be used the problem is to measure very small intervals of time very accurately. Light will travel one mile in about the one hundred and eighty-sixth thousandth part of a second, and if by using a mile as the distance the velocity of light is to be determined within one per cent., it is necessary to be able to detect differences of time as small as about one twenty-millionth of a second. This has been made possible by the use of two distinct methods. Foucault, on the suggestion of Arago, used a rapidly revolving mirror, a method introduced by Wheatstone, the English electrician, who used it in finding the duration of an electric spark."}]}
{"messages": [{"role": "assistant", "content": "Foucault, on the suggestion of Arago, used a rapidly revolving mirror, a method introduced by Wheatstone, the English electrician, who used it in finding the duration of an electric spark. The essential principle is that a mirror may be made to revolve so rapidly that it will change its position by a measurable angle, while light which has been reflected from it passes to a somewhat distant fixed mirror and returns to the moving reflector. In the other method a toothed wheel is revolved so rapidly that a beam of light passing between two consecutive teeth to a distant fixed mirror is cut off on its return to the wheel by the tooth, which has moved forward while the light has made its journey. This method was first used by Fizeau. In either method, if the speed of rotation is known, the time is readily found. In point of time, Fizeau was the first to attack the problem, which he did about 1849."}]}
{"messages": [{"role": "assistant", "content": "In point of time, Fizeau was the first to attack the problem, which he did about 1849. Foucault was perhaps a year later in getting results, but his method is generally considered the best. Both methods have been used by other experimenters, and very important improvements in Foucault’s method were made in the United States by Michelson about 1878. Michelson’s method increased enormously the precision of the measurements, and it has been applied by him and by Newcomb, not only for the better determination of the velocity of light in air, but for the solution of many other related problems of first importance. Michelson’s final determination of the absolute velocity of light (in the ether) is everywhere accepted as authoritative. Another discovery in optics entirely accomplished during the nineteenth century and of the very first importance is generally known as “Spectrum Analysis.” This discovery has not yet ceased to excite admiration and even amazement, and especially among those who best understand it."}]}
{"messages": [{"role": "assistant", "content": "Another discovery in optics entirely accomplished during the nineteenth century and of the very first importance is generally known as “Spectrum Analysis.” This discovery has not yet ceased to excite admiration and even amazement, and especially among those who best understand it. By its use hitherto unknown substances have become known; to the physicist it is an instrument of research of the greatest power, and perhaps more than anything else it promises to throw light on the ultimate nature of matter; to the astronomer it has revealed the composition, physical condition, and even the motions of the most distant heavenly bodies, all of which the philosophy of a hundred years ago would have pronounced absolutely impossible. The beginning of spectrum analysis was in 1802, when an Englishman, Dr. Wollaston, observed dark lines interrupting the solar spectrum when produced by a good prism upon which the sunlight fell after passing through a narrow slit. About ten years later, Fraunhofer, at Munich, a skilful worker in glass and a keen observer, discovered in the spectrum of light from a lamp two yellow bands, now known as the sodium, or “D” lines. Combining the three essential elements of the modern spectroscope, the slit, the prism, and the observing telescope, he saw in the spectrum of sunlight “an almost countless number of dark lines.” He was the first to use a grating for the production of the spectrum, using at first fine wire gratings and afterwards ruling fine lines upon glass, and with these he made the first accurate measures of the length of light waves."}]}
{"messages": [{"role": "assistant", "content": "Combining the three essential elements of the modern spectroscope, the slit, the prism, and the observing telescope, he saw in the spectrum of sunlight “an almost countless number of dark lines.” He was the first to use a grating for the production of the spectrum, using at first fine wire gratings and afterwards ruling fine lines upon glass, and with these he made the first accurate measures of the length of light waves. He did not, however, comprehend the full import of the problem which he thus brought to the attention of physicists. About twenty years later Sir John Herschell studied the bright line spectra of different substances and found that they might be used to detect the presence of minute quantities of a substance whose spectrum was known. Wheatstone studied the spectrum of the electric arc passing between metals, and in 1874 Dr. J. W."}]}
{"messages": [{"role": "assistant", "content": "W. Draper published a very important paper on the spectra of solids with increasing temperature. Although quite in the dark as to the real nature of the phenomena with which they were dealing, these observers paved the way for the splendid work of the two Germans, Kirchoff and Bunsen, who, about 1860, found the key to this wonderful problem and made the science of spectrum analysis substantially what it is to-day. Its fundamental principles may be considered as few and comparatively simple. Waves of light and radiant heat originate in ether disturbances produced by molecular vibration, and have impressed upon them all of the important qualities of that vibration. Molecules of different substances differ in their modes of vibration, each producing a wave peculiar to and characteristic of itself."}]}
{"messages": [{"role": "assistant", "content": "Molecules of different substances differ in their modes of vibration, each producing a wave peculiar to and characteristic of itself. A useful analogy may be found in the fact that when one listens to the music of an orchestra without seeing it it is easy to recognize the tones that come from each of the several instruments, the characteristic vibrations of each being impressed upon the waves in air which carry the sound to the ear. So delicate and so sure is this impression of vibration peculiarities that it is even possible to know the maker of a violin, for instance, by a characteristic _timbre_ which must have its physical expression in the sound wave. The ear, more perfect than the eye, analyzes the resultant disturbance into its component parts so that each element may be attributed to its proper source. Unaided, the eye cannot do this with light, but the spectroscope separates the various modes of vibration which make up the confused whole, so that varieties of molecular activity are recognizable. The speed at which a source of sound is approaching or receding from the ear can be ascertained by noting the rise or fall in pitch due to the crowding together or stretching out of the sound waves, and in the same way the motion of a luminous body is known from the increase or decrease of the refrangibility of the elements of its spectrum."}]}
{"messages": [{"role": "assistant", "content": "The speed at which a source of sound is approaching or receding from the ear can be ascertained by noting the rise or fall in pitch due to the crowding together or stretching out of the sound waves, and in the same way the motion of a luminous body is known from the increase or decrease of the refrangibility of the elements of its spectrum. Indeed, had nineteenth-century science accomplished nothing else than the discovery of spectrum analysis, it would have marked the beginning of a new epoch. By this device man is put in communication with every considerable body in the universe, including even the invisible. The “goings on” of Sirius and Algol, of Orion and the Pleiads are reported to him across enormous stretches of millions of millions of miles of space, empty save of the ethereal medium itself, by this most wonderful “wireless telegraphy.” And it is by the vibratory motion of the invisibly small that all of this is revealed; the infinitely little has enabled us to conquer the inconceivably big. Many important contributions to the theory and practice of spectrum analysis have been made since the time of Kirchoff and Bunsen, only two or three of which can be referred to here. Instrumental methods by which spectra are produced and examined have been greatly perfected, and this is especially true of what is known as the “diffraction grating” first used by Fraunhofer."}]}
{"messages": [{"role": "assistant", "content": "Instrumental methods by which spectra are produced and examined have been greatly perfected, and this is especially true of what is known as the “diffraction grating” first used by Fraunhofer. A quarter of a century ago Rutherford, of New York, constructed a ruling engine by means of which gratings on glass and spectrum metal were ruled with a precision greatly exceeding what had before been possible. A few years later Rowland, of Baltimore, made a notable advance in the construction of a screw far more perfect than any before made, producing gratings of a fineness and regularity of spacing far ahead of any others, and especially by the capital discovery of the concave grating, by means of which the most beautiful results have been obtained. Very recently Michelson, of Chicago, has invented the echelon spectroscope, which, although greatly restricted in range, exceeds all others in power of analysis of spectral lines. In his hands this instrument has been most effective in the study of the influence of a strong magnetic field upon the character of the spectrum from light produced therein, a most interesting phenomenon first observed by Zeeman and one which promises to reveal much concerning the relation of molecular activity to light and to magnetic force. The development of spectrum analysis was necessarily accompanied by a recognition of the identity of radiant heat and light."}]}
{"messages": [{"role": "assistant", "content": "The development of spectrum analysis was necessarily accompanied by a recognition of the identity of radiant heat and light. The study of radiant heat, which was carried on during the earlier years of the century by Leslie, and later by Melloni and Tyndall, by what might be called thermal methods, has been industriously pursued during the last two decades by processes similar to those adopted for visual radiation. The most notable contribution to this work is the invention of the _bolometer_, by Langley, who, at Allegheny, and later at Washington, has made exhaustive studies of solar radiation in invisible regions of the spectrum, especially among the waves of greater length than those of red light, where he has found absorption lines and bands similar in character to those observed in the visible spectrum. He has also studied the absorption of the earth’s atmosphere, the relation of energy to visual effect, and many other interesting problems, the solution of which was made possible by the use of the bolometer. Mention must also be made of the invention by Michelson of an interference comparator, by means of which linear measurements by optical methods can be accomplished with a degree of accuracy hitherto unheard of. With this instrument Michelson has determined the length of the international prototype metre in terms of the wave length of the light of a particular spectral line, thus furnishing for the first time a satisfactory _natural_ unit of length."}]}
{"messages": [{"role": "assistant", "content": "With this instrument Michelson has determined the length of the international prototype metre in terms of the wave length of the light of a particular spectral line, thus furnishing for the first time a satisfactory _natural_ unit of length. By far the most important contribution to the theory of light made during the last half of the century is that of Maxwell, who, in 1873, announced the proposition that electro-magnetic phenomena and light phenomena have their origin in the same medium, and that they are identical in nature. This far-reaching conclusion has been generally accepted and formed the basis of much of the most important work in physical research in process of elaboration as the century closed. To some of this reference will presently be made. ELECTRICITY AND MAGNETISM \nIn no other department of physical science have such remarkable developments occurred during the past century as in electricity and magnetism, for in no other department have the practical applications of scientific discovery been so numerous and so far reaching in their effect upon social conditions. In a brief review of the contributions of the nineteenth century to the evolution of the telegraph, telephone, trolley-car, electric lighting, and other means of utilizing electricity, it will be possible to consider only a very few of the fundamental discoveries upon which the enormous and rather complex superstructure of to-day rests."}]}
{"messages": [{"role": "assistant", "content": "In a brief review of the contributions of the nineteenth century to the evolution of the telegraph, telephone, trolley-car, electric lighting, and other means of utilizing electricity, it will be possible to consider only a very few of the fundamental discoveries upon which the enormous and rather complex superstructure of to-day rests. Happily these are few in number, and their presentation is all the more important because of the fact that in the popular mind they are not accorded that significance to which they are entitled, if, indeed, they are remembered at all. The first great step in advance of the electricity of Franklin and his contemporaries (and his predecessors for two thousand years) was taken very near the end of the eighteenth century, but it must be regarded as the beginning of nineteenth-century electricity. Two Italian philosophers, Galvani and Volta, contributed to the invention of what is known as the galvanic or voltaic battery, the output of which was not at first distinctly recognized as the electricity of the older schools. By this beautiful discovery electricity was for the first time enslaved to man, who was now able to generate and control it at times and in such quantities as he desired. Although the voltaic battery is now nearly obsolete as a source of electricity, its invention must always be regarded as one of the three epoch-making events in the history of the science during the past one hundred and twenty years."}]}
{"messages": [{"role": "assistant", "content": "Although the voltaic battery is now nearly obsolete as a source of electricity, its invention must always be regarded as one of the three epoch-making events in the history of the science during the past one hundred and twenty years. For three-quarters of a century it was practically the only source of electricity, and during this time and by its use nearly all of the most important discoveries were made. Even in the first decade of the century many brilliant results were reached. Among the most notable were the researches of Sir Humphry Davy, who, by the use of the most powerful battery then constructed, resolved the hitherto unyielding alkalies, discovering sodium and potassium, and at the same time exhibited in his lectures in the Royal Institution in London the first electric arc light, the ancestor of the millions that now turn night into day. The cost of generating electricity by means of a voltaic battery is relatively very great, and this fact stood in the way of the early development of its applications, although their feasibility was perfectly well understood. Without any other important invention or discovery than that of the voltaic battery much would have been possible, including both electric lighting and the electric telegraph."}]}
{"messages": [{"role": "assistant", "content": "Without any other important invention or discovery than that of the voltaic battery much would have been possible, including both electric lighting and the electric telegraph. Indeed, electric telegraphy had long been a _possibility_, even before the time of Galvani and Volta, but its actual construction and use was almost necessarily postponed until a second capital discovery came to remove most of the difficulties. This was the discovery of a relation between electricity and magnetism, the existence of which had long been suspected and earnestly sought. A Danish professor, Hans Christian Oersted, was fortunate in hitting upon an experiment which demonstrated this relation and opened up an entirely new field of investigation and invention. What Oersted found was that when a conductor, as a copper wire, carrying an electric current, was brought near a freely suspended magnet, like a compass needle, the latter would take up a definite position with reference to the current. Thus an electric current moved a magnet, acted like a magnet in producing a “magnetic field.” The subject was quickly taken up by almost every physicist in Europe and America."}]}
{"messages": [{"role": "assistant", "content": "Thus an electric current moved a magnet, acted like a magnet in producing a “magnetic field.” The subject was quickly taken up by almost every physicist in Europe and America. Arago found that iron filings would cling to a wire through which a current was passing, and he was able to magnetize steel needles by means of the current. Ampère, another French physicist, studied Oersted’s wonderful discovery both experimentally and mathematically, and in an incredibly short time so developed it as to deserve the title of creator of the science of electro-dynamics. The first to make what is known as an electro-magnet was an Englishman named Sturgeon, who used a bar of soft iron bent in a horseshoe form (as had long been common in making permanent steel magnets), and, after varnishing the iron for insulation, a single coil of copper wire was wrapped about it, through which the current from a battery was passed. There were thus two ways of producing visible motion by means of an electric current: that of Oersted’s simple experiment, in which a suspended magnetic needle was deflected by a current, and that made possible by the production, at will, of an electro-magnet. The application of both of these ideas to the construction of an electric telegraph was quickly attempted, and two different systems of telegraphy grew out of them."}]}
{"messages": [{"role": "assistant", "content": "The application of both of these ideas to the construction of an electric telegraph was quickly attempted, and two different systems of telegraphy grew out of them. One, depending on Oersted’s experiment, was developed in England first and afterwards in Europe; the other, that involving the use of signals produced by an electric magnet, was developed in America, and was generally known as the American method. It has long ago superseded the first method in actual practice. Its possibility depended on perfecting the electro-magnet and especially on an understanding of the principles on which that perfecting depended. For the complete and satisfactory solution of this problem we are indebted to the most famous student of electricity America has produced during the century, Joseph Henry. In 1829, while a teacher in the academy at Albany, New York, Henry exhibited an electro-magnet of enormously greater power than any before made, involving all of the essential features of the magnet of to-day."}]}
{"messages": [{"role": "assistant", "content": "In 1829, while a teacher in the academy at Albany, New York, Henry exhibited an electro-magnet of enormously greater power than any before made, involving all of the essential features of the magnet of to-day. The wire was insulated by silk wrapping, and many coils were placed upon the iron core, the intensity of magnetization being thus multiplied. Henry studied, also, the best form and arrangement of the battery under varying conditions of the conductor. An electro-magnetic telegraph had been declared impossible in 1825, by Barlow, an Englishman, who pointed out the apparently fatal fact that the resistance offered to the current was proportional to the length of the conducting wire and that the strength of the current would be thus so much reduced for even short distances as to become too feeble to be detected. Henry showed that what is known as an “intensity battery” would overcome this difficulty, discovering experimentally and independently the beautifully simple law showing the relation of current to electro-motive force which Ohm had announced in 1827. He also invented the principle of the relay, by which the action of a very feeble current controls the operation of a more powerful local system."}]}
{"messages": [{"role": "assistant", "content": "He also invented the principle of the relay, by which the action of a very feeble current controls the operation of a more powerful local system. It will thus be seen that the essential features of the so-called American system of telegraphy are to be credited to Henry, who had a working line in his laboratory as early as 1832. Morse made use of the scientific discoveries and inventions of Henry, and by his indefatigable labors and persistent faith the commercial value of the enterprise was really established. In the mean time considerable progress was made in Europe. Baron Schilling, a Russian Councillor of State, devised and exhibited a needle telegraph. The two illustrious German physicists, Gauss and Weber, established a successfully working line two or three miles long in 1833, and this system was commercially developed by Steinheil in 1837."}]}
{"messages": [{"role": "assistant", "content": "The two illustrious German physicists, Gauss and Weber, established a successfully working line two or three miles long in 1833, and this system was commercially developed by Steinheil in 1837. In England, Sir Charles Wheatstone made many important contributions, although using the needle system, which was afterwards abandoned. Before the middle of the century the commercial success of the electro-magnetic telegraph was assured, and in the matter of the transmission of messages distance was practically annihilated. Oersted, Arago, Ampère, Sturgeon, and Henry had made it possible to convert electricity into mechanical energy. Motors of various types had been invented, and the possibility of using the new source of power for running machinery, cars, boats, etc., was fully recognized. Several attempts had been made to do these things, but the great cost of producing the current by means of a battery stood in the way of success."}]}
{"messages": [{"role": "assistant", "content": "Several attempts had been made to do these things, but the great cost of producing the current by means of a battery stood in the way of success. Another epoch-making discovery was necessary, namely, a method of reversing the process and converting mechanical energy into electricity. This was supplied by the genius of Michael Faraday, who had succeeded Davy in the Royal Institution at London. In 1831 Faraday discovered _induction_, the key to the modern development of electricity. He showed that while Oersted had proved that a current of electricity would generate a magnetic field and set a magnet in motion, this process was reversible. A magnet set in motion in a magnetic field by a steam-engine or any other source of power would produce, in a conductor properly arranged, a current of electricity, and thus the dynamo came into existence."}]}
{"messages": [{"role": "assistant", "content": "A magnet set in motion in a magnetic field by a steam-engine or any other source of power would produce, in a conductor properly arranged, a current of electricity, and thus the dynamo came into existence. In this brilliant investigation he was almost anticipated by Henry, who was working at Albany along the same lines, but under much less favorable conditions. Indeed, in several of the most important points, the American actually did anticipate the Englishman. Nearly half a century elapsed before this most important discovery was sufficiently developed to become commercially valuable, and it is impossible in this place to trace the steps by which, during the last quarter of a century, the production and utilization of electricity as existing to-day was accomplished, as a result of which the century closed, as one might say, in a blaze of light; and it is unnecessary, because most people have witnessed the spread of the fire which Faraday and Henry kindled. Faraday’s discovery of induction furnished the basis of that marvellous improvement upon the telegraph by which actual speech is transmitted over hundreds and even thousands of miles. In connection with the invention of the telephone the names of Philip Reiss, Graham Bell, Elisha Gray, and Dolbear will always be mentioned, each of whom, doubtless independently, hit upon a way of accomplishing the result with more or less success."}]}
{"messages": [{"role": "assistant", "content": "In connection with the invention of the telephone the names of Philip Reiss, Graham Bell, Elisha Gray, and Dolbear will always be mentioned, each of whom, doubtless independently, hit upon a way of accomplishing the result with more or less success. To Bell, however, belongs the honor of having first practically solved the problem and of devising a system which, with numerous modifications and improvements, has come into extensive use in all parts of the world. No other application of electricity has come into such universal use, and none has contributed more to the comfort of life. While it is doubtless true that since Faraday’s time no discovery comparable with his in real importance has been made, the past twenty-five years have not lacked in results of scientific research, some of which may, in the not distant future, eclipse even that in the value of their practical applications. Among these must be ranked Clerk Maxwell’s theory of electric waves and its beautiful verification in 1888 by the young German physicist, Hertz. This brilliant student of electricity succeeded in actually producing, detecting, and controlling these waves, and out of this discovery has come the “wireless telegraphy” which has been so rapidly developed within the last few years."}]}
{"messages": [{"role": "assistant", "content": "This brilliant student of electricity succeeded in actually producing, detecting, and controlling these waves, and out of this discovery has come the “wireless telegraphy” which has been so rapidly developed within the last few years. Many other discoveries in electricity of great scientific interest and practical promise have been recorded in the closing years of the century, but the necessary limits of this article forbid their consideration. No account of the progress of physical science during the nineteenth century would be even approximately complete without mention of other investigations of profound significance. For instance, the study of the phenomena of sound has yielded results of great scientific and some practical value. The application of the theory of interference by Thomas Young; the publication of Helmholtz’s great work, the _Tonempfindungen_, in which his theory of harmony was first fully presented; the publication of Lord Rayleigh’s treatise; the invention and construction by König of acoustic apparatus, the best example yet furnished of scientific handicraft; all of these mark important advances, not only in acoustics but in general physics as well. The phonautograph of Scott and König, by which a graphic record of the vibrations of the vocal chords was made possible, was ingeniously converted by Edison into a speech recording and reproducing machine, the phonograph, by which the most marvellous results are accomplished in the simplest possible manner."}]}
{"messages": [{"role": "assistant", "content": "The phonautograph of Scott and König, by which a graphic record of the vibrations of the vocal chords was made possible, was ingeniously converted by Edison into a speech recording and reproducing machine, the phonograph, by which the most marvellous results are accomplished in the simplest possible manner. The century is also to be credited with the discovery and development of the art of photography, which, although not of the first importance, has contributed much to the pleasure of life, and as an aid to scientific investigation has become quite indispensable. The wonderfully beautiful experiments of Sir William Crookes, on the passage of an electric discharge through a high vacuum, and other phenomena connected with what has been called “radiant matter,” begun about a quarter of a century ago and continued by him and others up to the present time, laid the foundation for the brilliant work of Röntgen in the discovery and study of the so-called “X”-rays, the real nature of which is not yet understood. Their further investigation by J. J. Thomson, Becquerel, and others, seems to have revealed new forms and phases of radiation, a fuller knowledge of which is likely to throw much light on obscure problems relating to the nature of matter."}]}
{"messages": [{"role": "assistant", "content": "Thomson, Becquerel, and others, seems to have revealed new forms and phases of radiation, a fuller knowledge of which is likely to throw much light on obscure problems relating to the nature of matter. Concerning the “Nature of Matter,” the ablest physicists of the century have thought and written much, and doubtless our present knowledge of the subject is much more nearly the truth than that of a hundred years ago. The molecular theory of gases has met with such complete experimental verification, and is so in accord with all observed phenomena, that it must be accepted as essentially correct. As to the ultimate nature of what is called matter, as distinguished from the ethereal medium, what is known as the “vortex theory of atoms” has received the most consideration. This theory was developed by Lord Kelvin out of Helmholtz’s mathematical demonstration of the indestructibility of a vortex ring when once formed in a medium possessing the properties which are generally attributed to the ether. Perhaps the most remarkable as well as the most promising fact relating to physical science at the close of the nineteenth century is the great and rapidly increasing number of well-organized and splendidly equipped laboratories in which original research is systematically planned and carried out."}]}
{"messages": [{"role": "assistant", "content": "Perhaps the most remarkable as well as the most promising fact relating to physical science at the close of the nineteenth century is the great and rapidly increasing number of well-organized and splendidly equipped laboratories in which original research is systematically planned and carried out. When one reflects that for the most part during the century just ended the advance of science was more or less of the nature of a guerrilla warfare against ignorance, it seems safe to predict for that just beginning victories more glorious than any yet won. T. C. MENDENHALL. WAR \n\nIt is doubtful how far, even if as civilians we get over our natural dislike of talking of military change as “progress,” there has been any considerable advance in the larger aspects of military science within the century."}]}
{"messages": [{"role": "assistant", "content": "WAR \n\nIt is doubtful how far, even if as civilians we get over our natural dislike of talking of military change as “progress,” there has been any considerable advance in the larger aspects of military science within the century. The genius of Bonaparte, working upon the foundations laid by Frederick the Great, established a century ago principles which are essentially applicable to the military matters of the present day; and although the scientific developments of artillery and musketry have affected the dispositions of battle-fields, the essential principles of the art of preparation for war and of strategy stand where they stood before. Scharnhorst was the Prussian officer who began to reduce the Napoleonic military system to rules applicable to the use of German armies. Under Bonaparte the whole management of the army was too often concentrated in the hands of the man of genius, and the actual method of Napoleon had the defect that, failing the man of genius at the head of the army, it broke down. The main change made by the Germans, who followed Scharnhorst, in the course of the century has been to codify the Napoleonic system so that it was possible to more generally decentralize in practice without impairing its essence. They have also established a division of its supply department (under a Minister of War) from the “brain of the army,” as Mr."}]}
{"messages": [{"role": "assistant", "content": "They have also established a division of its supply department (under a Minister of War) from the “brain of the army,” as Mr. Spenser Wilkinson has well called it, which manages the preparation for the strategy of war and the strategy itself. These so-called Prussian principles of decentralization and “initiative” are, however, not new and not Prussian, and may be discovered in the conversations of Napoleon Bonaparte. The French in 1870 had forgotten his teaching, and the Germans had retained it. It is, nevertheless, the case that the number of men placed in the field by the military powers having increased, the intelligent initiative of corps commanders and even of generals commanding divisions has become the more essential. It is impossible that the great general staff can give orders in advance which will cover the responsibility of all the inferior generals, and brains have to be added in all ranks to obedience."}]}
{"messages": [{"role": "assistant", "content": "It is impossible that the great general staff can give orders in advance which will cover the responsibility of all the inferior generals, and brains have to be added in all ranks to obedience. The commander-in-chief in the field cannot with advantage drown himself in details, and he can only provide in his orders an outline sketch which his subordinates in various parts of the field of operations have to fill in. The “initiative of subordinates” is but the natural division of labor. If I, a civilian student of military politics, rather than a military expert, have been called upon to write upon the military progress of the century, it must be because of a desire to bring largely into the account the changes in military organization which on the continent of Europe have made it permanently national, and which in the United States made it temporarily national during the Civil War, and would make it so again in the event of any fresh struggle on a great scale in which the North American continent might become involved. Although the “armed nation” has replaced in France, Germany, Switzerland, Austria-Hungary, Italy, Roumania, and Bulgaria the smaller professional armies of the eighteenth century, the popular belief that the numerical strength of field armies has enormously increased is not so completely well founded as at first sight might be supposed. It is true that each nation can put into the entire field of warfare larger numbers than that nation could put into the field a century ago."}]}
{"messages": [{"role": "assistant", "content": "It is true that each nation can put into the entire field of warfare larger numbers than that nation could put into the field a century ago. But it is still not beyond the bounds of possibility that in certain cases small armies may produce results as remarkable as those which attended British operations in the Peninsula in the early part of the nineteenth century, and, on the other hand, although there will, upon the whole, in future continental wars, be larger armies in the field, no one general is likely personally to handle or to place upon a field of battle a larger army than that with which Napoleon traversed Europe before he invaded Russia. The principles of pure military science as set forth in books have not been greatly changed during the nineteenth century. The Prussian Clausewitz only explained for us the doctrines of Bonaparte; and the latest writers—such as the Frenchmen Derrécagaix and Lewal—only continue Clausewitz. The theory of the armed nation has received extension, but, after all, the Prussian system in its essentials dates from Jena, and the steps by which it has produced the admirable existing armies of France, Austria, and Roumania have been but slow. The United States stand apart."}]}
{"messages": [{"role": "assistant", "content": "The United States stand apart. Their resources are so fabulously great that they and they alone are able to wait for war before making war preparations. No power will attack the United States. All powers will submit to many things and yield many strong points rather than fight the United States. The only territorial neighbors of the republic are not only not in a position to enter into military rivalry with her on the American continent, but are not advancing their military establishments with the growth of their or of her population. They are of themselves not only unable to attack, but equally unable in the long run effectively to resist her."}]}
{"messages": [{"role": "assistant", "content": "They are of themselves not only unable to attack, but equally unable in the long run effectively to resist her. The whole question, then, unfortunately for us Europeans, is a European question, and I need make but little reference to happier lands across the greater seas. In Europe the United Kingdom stands absolutely apart. The existence of the British Empire depends less upon our armies than on our fleets. India is garrisoned by a small but costly army, sufficient for present needs, but insufficient to meet their probable growth. The home army, kept mainly in England and Ireland (and in Ireland now only because life is cheap in Ireland and the country healthy and well fitted for the drill and discipline of troops), has been chiefly a nursery for the white army in India, and will be for that in South Africa and in India."}]}
{"messages": [{"role": "assistant", "content": "The home army, kept mainly in England and Ireland (and in Ireland now only because life is cheap in Ireland and the country healthy and well fitted for the drill and discipline of troops), has been chiefly a nursery for the white army in India, and will be for that in South Africa and in India. The expeditions which the country is obliged to send from time to time across the seas have but a domestic interest, and are unimportant when viewed from a world-wide military stand-point. In the event of war the attention of the country would be concentrated upon her fleets, with a view to retain that command of the sea without which her old-fashioned army would be useless. Belgium has an old-fashioned army of another type. A small force of conscripts is “drawn” and the men are allowed to find substitutes for money. But Belgium and the other smaller Powers, except Switzerland, Roumania, and Bulgaria, may be neglected in our survey."}]}
{"messages": [{"role": "assistant", "content": "But Belgium and the other smaller Powers, except Switzerland, Roumania, and Bulgaria, may be neglected in our survey. Switzerland has developed an excellent army of a special local type, a cheap but highly efficient militia, the most interesting point about which is that, while field artillery is supposed to be difficult of creation and only to be obtained upon a costly and regular system, Switzerland produces an excellent field artillery upon a militia footing. The garrison artillery militia of Great Britain have longer training than the field artillery of the Swiss Federation, but the results of the training are very different. Similarly, while cavalry is supposed to be in the same position as artillery in these matters, Hungary produces a good cavalry upon a militia system. It is, however, to the native army in India that we have to turn if we want to see what long service cavalry in past centuries used to be, for in these days of shorter service cavalry at least has suffered a decline, and, so far from cavalry, on the whole, presenting us with a picture of military progress in the century, the cavalry of the present day is not to be compared with the cavalry of the past. Roumania and Bulgaria, although small countries, have remarkable armies of the most modern type, of great strength when considered proportionately to their populations; but these need not come under our examination, because substantially they are on the Prussian plan."}]}
{"messages": [{"role": "assistant", "content": "Roumania and Bulgaria, although small countries, have remarkable armies of the most modern type, of great strength when considered proportionately to their populations; but these need not come under our examination, because substantially they are on the Prussian plan. Russia differs from Germany, France, and Austria in having an immense peace army. Her peace army is indeed as large as that of the whole of the Triple Alliance, and the enormous distances of Russia and the difficulties of mobilization and concentration force her into the retention and development of a system which is now peculiar to herself. The armies of Russia resemble more closely (although on a far larger scale) the old armies of the time before the changes which followed 1866 than the French, German, and Austrian armies of to-day. Italy is decreasing her army, and has been driven by her financial straits to completely spoil a system which was never good except on paper. It is doubtful whether now in a sudden war the Italians could put into the field any thoroughly good troops, except their Alpine battalions, which are equal to those of the French."}]}
{"messages": [{"role": "assistant", "content": "It is doubtful whether now in a sudden war the Italians could put into the field any thoroughly good troops, except their Alpine battalions, which are equal to those of the French. The Austrian system does not differ sufficiently from those of Germany and of France to be worthy special note, although it may be said in passing that the Austrian army is now considered by competent observers to be excellent. We may take as our type of the armies of to-day those of Germany and of France. These armies are also normal as regards their cost. Great Britain having no conscription, and being in the habit of paying dearly for all services, is extravagant in her military expenditure for the results obtained. Switzerland and Russia, with their different systems, and for different reasons, obtain their armies very cheaply; and if we wish to know the cost of the modern military system it is to Germany and to France that we should turn."}]}
{"messages": [{"role": "assistant", "content": "Switzerland and Russia, with their different systems, and for different reasons, obtain their armies very cheaply; and if we wish to know the cost of the modern military system it is to Germany and to France that we should turn. Those who would study the French or German army for themselves will find a large literature on the subject. The principles which govern the establishment of an armed nation upon the modern Prussian scale, improved after the experiences of 1866 and again after those of 1870, are explained in the work of Von der Goltz, _The Nation in Arms_. Those who would follow these principles into their detailed application, and see how the armies are divided between, and nourished and supplied from the military districts of one of the great countries, will find the facts set forth in such publications as the illustrated _Annual of the French Army_, published each year by Plon, Nourrit, et Cie., or in the official handbooks published by the Librairie Militaire Baudoin. In the time of Bonaparte and even in the time of the Second Empire in France army corps were of varying strength, and there was no certain knowledge on the part of administrators less admirable than the first Napoleon himself of the exact numbers of men who could be placed in the field. In 1870 Louis Napoleon was wholly misinformed as to his own strength and as to that of his opponents, which were, however, accurately known to Von Moltke."}]}
{"messages": [{"role": "assistant", "content": "In 1870 Louis Napoleon was wholly misinformed as to his own strength and as to that of his opponents, which were, however, accurately known to Von Moltke. In these days such confusions and difficulties are impossible. The army corps of the great military powers are of equal strength and would be equally reinforced in the extraordinarily rapid mobilization which would immediately precede and immediately follow a declaration of war. The chief changes in the century have been a greater exactitude in these respects, a general increase of numbers (especially a great increase in the strength of field artillery), and in these last years a grouping of the army corps into armies, which exist in Germany, France, and Russia even in time of peace, with all their generals and staffs named ready for war. In each of the great military countries the army is guided by the counsel of a general staff. Around the chief of the staff and the Minister of War are the “generals of armies,” and in France a potential generalissimo (who on the outbreak of war would often be superseded by another general in the actual command)."}]}
{"messages": [{"role": "assistant", "content": "Around the chief of the staff and the Minister of War are the “generals of armies,” and in France a potential generalissimo (who on the outbreak of war would often be superseded by another general in the actual command). In the case of Germany the command would now be exercised by the young Emperor. In the case of France it would be exercised by the generalissimo, with the chief of the staff as his “Berthier” or major-general. Enormously important duties in the case of armies so unwieldy as the entire forces of the first line and of the second line in Germany or France and of the first line in Russia would be exercised by the “generals of armies.” These generals in time of peace are called “inspectors of armies” in France, Germany, and Austria, and they inspect groups of army corps which would be united in war to form the armies which these generals would actually command. These generals also form the council of war or principal promotion board and committee of advice for the generalissimo and chief of the staff. In Germany and in Austria-Hungary the German Emperor and the Emperor-King respectively are virtual general inspectors-in-chief of the whole army, but in France and in Russia there is less unity of command."}]}
{"messages": [{"role": "assistant", "content": "In Germany and in Austria-Hungary the German Emperor and the Emperor-King respectively are virtual general inspectors-in-chief of the whole army, but in France and in Russia there is less unity of command. The Minister of War in Russia, in Germany, and in France is intended to be at the head of the supplies of the army in time of war, directing the administration from the capital, and not taking his place in the field. The Prussian system, as far as the men are concerned, was adopted after the disasters of Prussia early in the century, in order to pass great numbers of men through the ranks without attracting attention by keeping up a large peace army. The system is now maintained by Germany, Austria, and France for a different reason. Such powers desire to have an enormous force for war, but, for budgetary reasons, to keep with the flag in time of peace the smallest force which is consistent with training the men sufficiently to enable them upon mobilization to be brought back to their regiments as real soldiers. It is these considerations which have induced the younger and more thoughtful of the Prussian generals to force on Germany a reduction of the period of infantry service to two years."}]}
{"messages": [{"role": "assistant", "content": "It is these considerations which have induced the younger and more thoughtful of the Prussian generals to force on Germany a reduction of the period of infantry service to two years. The army in time of peace becomes a mere training-school for war, and the service is made as short as possible, given the necessity of turning out a man who for some years will continue to have the traditions of a soldier. It is a question whether something has not been sacrificed, in France, at all events, to uniformity. A longer period of training is undoubtedly necessary to make an efficient cavalry soldier than is necessary to make an efficient infantry private; and a man who has served about two and a half years only in a cavalry regiment cannot in the majority of cases be brought back into the cavalry after he has returned to civil life. Cavalry, in the modern armies, is likely to be a diminishing force as war goes on. The armies will enter upon war with a number of infantry which can be kept up, the losses of war being supplied by reserve men as good as the men of the first line; but each army will enter upon war with a force of cavalry which will be rapidly destroyed if it is much used, and which will not be replaced in the same manner."}]}
{"messages": [{"role": "assistant", "content": "The armies will enter upon war with a number of infantry which can be kept up, the losses of war being supplied by reserve men as good as the men of the first line; but each army will enter upon war with a force of cavalry which will be rapidly destroyed if it is much used, and which will not be replaced in the same manner. The reserve cavalry of which the French press boasts is a paper force, and the pretended mobilization of two of its regiments a farce. The French would take the field with the cavalry of the first line only, seventy-nine regiments of five hundred horses (all over six years old), or less than half the eighty-four thousand cavalry with which Napoleon marched in 1812. The same thing might possibly be said of artillery as is said of cavalry but for the fact that Switzerland tells a different story as to the possibility of rapidly training artillerymen with a considerable measure of success. The French improvised artillery of the latter part of the war of 1870 were also a creditable force, while it was discovered to be impossible to create a cavalry. The efficiency of the reserves in France, Germany, and Austria is tested by the calling out of large portions of them every year for training, and they are found, as far as the infantry go, thoroughly competent for the work of war."}]}
{"messages": [{"role": "assistant", "content": "The efficiency of the reserves in France, Germany, and Austria is tested by the calling out of large portions of them every year for training, and they are found, as far as the infantry go, thoroughly competent for the work of war. The difficulties as regards cavalry are so obvious that it is becoming more and more recognized by Germany and by France that the cavalry will have to take the field as they stand in peace, and that their reserve men will have to be kept back with a view to the selection among them of those who are fit to serve as cavalry, and the relegation of the greater number to the train and other services where ability to ride and manage horses is more necessary than the smartness of a good cavalryman. France and Germany nominally look forward to the creation of two kinds of armies in time of war, one of the first line to take the field at once, and the other to guard the communications and garrison and support the fortresses, but in fact it is the intention of these powers to divide their armies into three—a field army of the first line, a field army of the second line, out of which fresh army corps will at once be created on the outbreak of war, and, thirdly, a territorial army for communications and for fortress purposes and as a last reserve. It is a portion of the French and German system that each army corps of the first line—and the same would be the case in war with the second line corps—has its separate organization of ammunition train and baggage train, and draws as largely as possible its supplies from its own territorial district. The peace strength of the great modern armies is for France and Germany about five hundred thousand men each, and the war strength between four million and five million men each. The peace strength of Russia is now over nine hundred thousand men."}]}
{"messages": [{"role": "assistant", "content": "The peace strength of Russia is now over nine hundred thousand men. Of the war armies the training is not uniformly complete, but there are in Germany, France, Austria, and Roumania sufficient reserves of clothing and rifles to equip the war armies of those powers for the field. The cost of the system of a modern army is very much less than that of the old-fashioned armies. The United Kingdom spent till lately (including loan money) about eighteen million pounds sterling upon her army, India rarely less than fourteen million pounds sterling and an average of fifteen million pounds, and the British Empire, outside the United Kingdom and India, two million pounds, or an average of thirty-five million pounds sterling in all upon land forces. The expenditure of the United Kingdom upon land forces has been permanently increased to an enormous extent by the South African war and cannot now be estimated. The expenditure of France and Germany upon land forces is greatly less; and of Russia, large as is her peace army, less again."}]}
{"messages": [{"role": "assistant", "content": "The expenditure of France and Germany upon land forces is greatly less; and of Russia, large as is her peace army, less again. But France and Germany in the event of war can immediately each of them place millions of armed men in the field in proper army formation and with adequate command, whereas the United Kingdom can place a doubtful three corps in the field in India with great difficulty, and, in the true sense of the word, no organized force at all at home without an incredible amount of reorganization and waste of time after the declaration of war. It is contended by the authorities responsible for the British army that two army corps could be placed in the field at home, and elaborate paper arrangements exist for this purpose; but the facts are as I state them, and not as they are professed to be. It is pretended that three corps of regulars were despatched to South Africa. But the cavalry and artillery were, in fact, created by lavish expenditure a long time after the war had begun and after disasters caused by their non-existence. Centralized as is the administrative system of France and Germany in everything except war, the necessities of modern warfare have forced upon the governments of those countries a large amount of decentralization as concerns military matters, and the less efficient military machines of the United Kingdom and of Russia are far more centralized than are the more efficient machines of Germany and of France."}]}
{"messages": [{"role": "assistant", "content": "Centralized as is the administrative system of France and Germany in everything except war, the necessities of modern warfare have forced upon the governments of those countries a large amount of decentralization as concerns military matters, and the less efficient military machines of the United Kingdom and of Russia are far more centralized than are the more efficient machines of Germany and of France. The army corps districts have in the latter countries so much autonomy as to recall to the political student the federal organization of the United States rather than the government of a highly centralized modern power. As soon, however, as war breaks out, the military states of time of peace would be grouped, and the four or five groups known as “armies,” also, of course, theoretically, brought together under the directing eye of the generalissimo. In the case, at all events, of Germany, unity of direction is perfectly combined with decentralization and individual initiative. The mode in which a modern army on the anticipation of war prepares itself for the field is extraordinarily rapid in point of time as compared with the mode found necessary in the time of Napoleon Bonaparte; and it is this rapidity of mobilization and concentration which strikes the observer as the greatest change or progress of the century in connection with armies. But it is a mere consequence of railroads and telegraphs, and is only the application to military purposes of those increased facilities of locomotion which have played so great a part in the progress of the century."}]}
{"messages": [{"role": "assistant", "content": "But it is a mere consequence of railroads and telegraphs, and is only the application to military purposes of those increased facilities of locomotion which have played so great a part in the progress of the century. Mobilization is, of course, the union at points fixed beforehand of the men of the reserves who bring the army up to its war footing, and the clothing and equipment of these men, and the distribution to the mobilized regiments of their full materials of war. The cavalry and horse artillery kept upon the frontier are now in a condition of permanent readiness in the principal military countries, as they would be used to cover the mobilization of the remainder of the army. The moment mobilization is accomplished concentration takes place—on the frontier in the case of the principal powers. Near the line of concentration are forts, which play a greater part in the French scheme of defence than they do in the German. The French in the days of their weakness after 1870 both constructed a line of intrenched camps and built a kind of wall of China along the most exposed portion of their eastern frontier; whereas the Germans are prepared to rely upon their field armies, supported by a few immense fortresses, such as those (on their western frontier) of Metz and Strasburg."}]}
{"messages": [{"role": "assistant", "content": "The French in the days of their weakness after 1870 both constructed a line of intrenched camps and built a kind of wall of China along the most exposed portion of their eastern frontier; whereas the Germans are prepared to rely upon their field armies, supported by a few immense fortresses, such as those (on their western frontier) of Metz and Strasburg. The French keep in front of their fortresses at Nancy a strong division, which is virtually always on a war footing, and both in France and Germany the frontier corps are at a higher peace strength than those of the interior, and are meant to take the field at once so as to help the cavalry and horse artillery to protect the mobilization and concentration of the remainder, and, if possible, to disturb the mobilization and concentration of the foe. Those who would study modern armies for themselves should visit Nancy and Metz, but should not neglect the Swiss annual manœuvres. The work of the recruit of Germany and of France, during his two years’ or nearly three years’ training as the case may be, is as hard as any human work; and the populations of the continental countries submit, not on the whole unwillingly, from patriotic motives, to a slavery of which the more fortunate inhabitants of the United Kingdom and of the United States have no conception. The British or the Belgian paid recruit would mutiny if forced to work as works the virtually unpaid and ill-fed recruit of Russia, Germany, Austria, and France. The enormous loss to many industries which is caused by the withdrawal of the men at the age of twenty, just when they are most apt to become skilled workmen, is in the opinion of some Germans compensated for by the habit of discipline and the moral tone of stiffness and endurance which is communicated to the soldier for the rest of his life."}]}
{"messages": [{"role": "assistant", "content": "The enormous loss to many industries which is caused by the withdrawal of the men at the age of twenty, just when they are most apt to become skilled workmen, is in the opinion of some Germans compensated for by the habit of discipline and the moral tone of stiffness and endurance which is communicated to the soldier for the rest of his life. This is perhaps more true of the German character than it is of the inhabitants of the other countries; and in France, at least, the soldier training of the entire population is a heavy drawback to industrial and to intellectual life. There are, however, as will be seen in the concluding passage of this article, other considerations to be taken into account, some of which tell the other way. The one successful exception to the prevailing military system of the day is to be found in Switzerland, which has a very cheap army of the militia type, but one which is, nevertheless, pronounced efficient by the best judges. The mobilization of Switzerland in 1870 was more rapid than that of either Germany or France, and, great as are the strides that both France and Germany have made in rapidity of organization and as regards numbers since 1870, the Swiss also have reorganized their mobilization system since that time, and are still able, at a much less proportional cost, to place in the field at least as large a proportional force as Germany, and this force believed to be efficient, although not largely provided with cavalry. The greatest change in the battle-fields of the future, as compared with those of a few years ago, will be found in the development and increased strength of the artillery."}]}
{"messages": [{"role": "assistant", "content": "The greatest change in the battle-fields of the future, as compared with those of a few years ago, will be found in the development and increased strength of the artillery. A modern army, when it takes up a position, has miles of front almost entirely occupied with guns, and the guns have to fire over the infantry, because there is no room for such numbers of guns to be used in any other way. The attacking side (if both, indeed, in one form or another, do not attempt attack) will be chiefly occupied in obtaining positions on which to place its guns, and the repeating-rifle itself, deadly as is its fire, cannot contend at ranges over a thousand yards, unless the riflemen are heavily intrenched, with the improved shrapnel fire of modern guns. The early engagements of a war will, indeed, be engagements of cavalry massed upon the frontier on the second day of mobilization, so rapid will the opening of war in the future be. This cavalry will be accompanied by horse artillery and followed by light infantry, constantly practised in rapid marching in time of peace, or by mounted infantry. But the great battle-fields of the later weeks will be battle-fields, above all, of artillery."}]}
{"messages": [{"role": "assistant", "content": "But the great battle-fields of the later weeks will be battle-fields, above all, of artillery. The numbers engaged will be so great that the heaviest of all the responsibilities of the generals will be the feeding of their troops during the battles prolonged during several days, which will probably occur, and it is doubtful how far the old generals (often grown unwieldy in time of peace) will be able to stand the daily and nightly strain of war. Jomini has said that when both sides are equally strong in numbers, in courage, and in many other elements of force, the great tragedy of Borodino is the typical battle. Lewal has pointed out that in the battles of the future such equality must be expected: “The battle will begin on the outbreak of war in the operations of the frontier regiments. The great masses as they come to the field will pour into a fight already raging. The battle will be immense and prolonged.” Promotion will probably be rapid among the generals, owing to incompetence and retirement, and certainly among other officers owing to their exposure in these days of smokeless powder, when good shots can pick off officers in a manner unknown in wars which have hitherto occurred."}]}
{"messages": [{"role": "assistant", "content": "The battle will be immense and prolonged.” Promotion will probably be rapid among the generals, owing to incompetence and retirement, and certainly among other officers owing to their exposure in these days of smokeless powder, when good shots can pick off officers in a manner unknown in wars which have hitherto occurred. Whether it will be possible to get armies to advance under heavy fire after the officers have been killed is doubtful, when we remember that modern armies consist of the whole population, cowards and brave men alike, and that regimental cohesion is weakened by the sudden infusion of an overwhelming proportion of reserve men at the last moment. On the other hand, in the German army the reserve men will be fewer in the first line than in the French, and the regimental system more available in the field, while on the French side the greater military aptitude of the French race may perhaps be counted upon to remedy the comparative defect. The Prussians make up for the inferior military aptitude of the German people by patriotism, discipline, and the conferring of honor and of civil employment, in after life, on all who do their duty in war. They also provide more effectively than do the French against incapacity in high place. Above all, however, we should attach importance to the wisdom of successive Kings of Prussia in treating the Prussian army as an almost sacred institution, and in constantly working in time of peace to make it and keep it a perfect instrument of war."}]}
{"messages": [{"role": "assistant", "content": "Above all, however, we should attach importance to the wisdom of successive Kings of Prussia in treating the Prussian army as an almost sacred institution, and in constantly working in time of peace to make it and keep it a perfect instrument of war. The weakest point, relatively speaking, in the French organization, and the strongest point, relatively speaking, in the German, is the officering of the second and third line. The one-year-volunteer system gives the Germans excellent “territorial” officers, while the French have been forced virtually to abolish it as impossible of successful application in a country so jealous of privilege as is modern France. The territorial infantry regiments of France would be excellent for the defence of fortresses, but would for field purposes be inferior to that part of the Prussian landwehr which would remain over after the completion of the reserve corps. The reserve cavalry regiments of France have been created in order to provide promotion and sinecure appointments, and would not produce a cavalry fit for true cavalry service in the field. It would carry us beyond the proper limits of this article to explain how it is that the French could create a field artillery of the second line in time of war which would probably be superior to that of Germany."}]}
{"messages": [{"role": "assistant", "content": "It would carry us beyond the proper limits of this article to explain how it is that the French could create a field artillery of the second line in time of war which would probably be superior to that of Germany. This forms a set-off against some other inferiority of the French. The newest point in the development of modern armies is the recent separation in the German army of the cavalry intended for patrol duties from the cavalry intended for fighting in the field. We have had to face the same problem in South Africa, but this condition of our war was peculiar. It has been said that the history of warfare is the history of the struggle among weapons, and that each change in tactics and even in strategy has come from scientific change affecting weapons. In the century we have seen the change from the smooth-bore to the rifle and from the ordinary to the repeating rifle."}]}
{"messages": [{"role": "assistant", "content": "In the century we have seen the change from the smooth-bore to the rifle and from the ordinary to the repeating rifle. We have seen the modifications of artillery, which are beginning to give an application of the quick-firing principle to field artillery, and the use of high explosive shells, likely to affect by their explosion even those who are near the bursting shell and who are not struck by its fragments. Smokeless powder has altered the look of battles and has reduced their noise. It provides excuse for the incompetent. It would be easy, however, to exaggerate the importance of these changes as regards tactics, and still more with regard to strategy, while with tactics we are not here concerned. The great continental military nations have hitherto not allowed themselves to be much affected by the changes in the weapons, and many of the modern fads which are adopted in small armies are condemned by the leaders of these great forces."}]}
{"messages": [{"role": "assistant", "content": "The great continental military nations have hitherto not allowed themselves to be much affected by the changes in the weapons, and many of the modern fads which are adopted in small armies are condemned by the leaders of these great forces. The British machine guns, for example, like British mounted infantry, are generally regarded on the continent as a fancy of our own. All nations have their military fads, except, perhaps, the severely practical Germans. Russia has its dragoon organization, from which it is receding; America has her dynamite gun; the French have their submarine torpedo-boats. Our machine guns are not thought much more of by most Prussians than the steam-gun of 1844, ridiculed by Dickens in _Martin Chuzzlewit_. If great change was to have been made in the art of war by modern weapons, one would have thought that the first things to disappear would be all vestige of protective armor and the use of cavalry in the field."}]}
{"messages": [{"role": "assistant", "content": "If great change was to have been made in the art of war by modern weapons, one would have thought that the first things to disappear would be all vestige of protective armor and the use of cavalry in the field. Yet protective armor has been recently restored to as large a proportion of many armies as used it in the wars of the beginning of the century, and the use of cavalry in the field is defended as still possible by all the highest authorities on the continent. My own opinion on such matters is that of a layman and should be worthless, but it agrees with that of several distinguished military writers. I confess that I doubt whether in future wars between good armies, such as those of France and Germany, it will be possible to employ cavalry on the field of battle, and I go so far as to think that the direct offensive, still believed in by the Prussians, will be found to have become too costly to be possible. Our South African experience is not, however, regarded by continental authorities as conclusive. The author of _Ironclads in Action_, Mr."}]}
{"messages": [{"role": "assistant", "content": "The author of _Ironclads in Action_, Mr. Wilson, who has made a very thorough study of the future of naval war, has pointed out with great force the most striking difficulties of war in the future as caused by the enormous concentration of forces in a particular tract of country. The result of that concentration must be great difficulties about supply, prolonged battles of an indecisive kind leading to exposure, absence of sleep, and to conditions which would form the severest strain for professional men of war, while those who will now be subject to them will be the ordinary population, not very specially warriors, except so far as patriotism may in some cases make up as regards courage and endurance for absence of military tradition. The vast number of wounded will be exposed for longer periods than was the case in many of the earlier wars; but when we remember Leipsic, and Dresden, and the retreat from Moscow, it is again easy to see that the change is rather in the direction of generalization of conditions, which were formerly exceptional, than a change to conditions wholly without precedent. I have all through this article written of Germany and France as the modern military countries to be taken as a standard in all comparisons. The French have imitated the Germans very closely since the war of 1870."}]}
{"messages": [{"role": "assistant", "content": "The French have imitated the Germans very closely since the war of 1870. But, although imitation is generally feeble, it must always be borne in mind that the French people have greater military aptitude than the German, and that unless beaten at the beginning of a war they are always in the highest degree formidable. The perfection of system is to be found in Germany, and the peculiarities of the German system are the combination of enlightened patriotism in all its individuality with iron discipline. The system is so strong that unless well managed it would crush out individual responsibility; but the system itself encourages this individual responsibility all down the gradations of the army to the humblest non-commissioned officer and even to the detached private. The universality of promotion by a certain high standard of merit and the absence of jobbery are more thoroughly obtained in Germany than in any other army, and Lord Wolseley’s criticisms on the 1898 manœuvres of our own army, criticisms renewed in 1900, in which he told us that no one had done well in the field, and that this proved that no one could have done his duty during the past year, would be impossible in Germany, and must have shocked military opinion throughout that country. It is not unusual to assume that the enormous military establishments of the continent of Europe are an almost unmixed evil."}]}
{"messages": [{"role": "assistant", "content": "It is not unusual to assume that the enormous military establishments of the continent of Europe are an almost unmixed evil. But this may perhaps be disputed on two grounds. In some cases, such as that of Italy, the army acts as a kind of rough national university in which the varied life of districts often discordant is fused into a patriotic whole, dialects are forgotten, and a common language learned. In the case of France the new military system is a powerful engine of democracy. There is a French prince (not of the blood) serving at this moment in a squad of which the corporal is a young peasant from the same department. A few years ago I found the Duc de Luynes, who is also Duc de Chaulnes and Duc de Chevreuse, the owner of Dampierre, the personal friend of kings, serving, by his own wish, for, as the eldest son of a widow, he was exempt, as a private of dragoons, and respectfully saluting young officers, some of whom were his own tenants."}]}
{"messages": [{"role": "assistant", "content": "A few years ago I found the Duc de Luynes, who is also Duc de Chaulnes and Duc de Chevreuse, the owner of Dampierre, the personal friend of kings, serving, by his own wish, for, as the eldest son of a widow, he was exempt, as a private of dragoons, and respectfully saluting young officers, some of whom were his own tenants. The modern military system of the continent, in the case of France and Germany at least, may also, I think, be shown to have told in favor of peace. It is possible for us to occasionally demand a war with the greater freedom, because we do not as a rule know what war means. Those of us who have seen something of it with our own eyes are a very small minority. But every inhabitant of France and Germany has the reality of war brought home to him with the knowledge that those of his own kin would have to furnish their tribute of “cannon flesh” (as the French and Germans call it) at the outbreak of any war; and the influence of the whole of the women of both countries is powerfully exerted in consequence upon the side of peace. CHARLES W."}]}
{"messages": [{"role": "assistant", "content": "CHARLES W. DILKE. NAVAL SHIPS \n\nIn the conditions of naval warfare the century now closed has seen a revolution unparalleled in the rapidity of the transition and equalled in degree only by the changes which followed the general introduction of cannon and the abandonment of oars in favor of sails for the propulsion of ships of war. The latter step was consequent, ultimately, upon the discovery of the New World and of the sea-passage to India by the Cape of Good Hope. The voyage to those distant regions was too long and the remoteness from ports of refuge too great for rowing galleys, a class of vessels whose construction unfitted them for developing great size and for contending with heavy weather. The change of motive power made possible and entailed a different disposition of the fighting power, the main battery weight of ships being transferred from the bows and sterns—end-on fire—to the broadsides."}]}
{"messages": [{"role": "assistant", "content": "The change of motive power made possible and entailed a different disposition of the fighting power, the main battery weight of ships being transferred from the bows and sterns—end-on fire—to the broadsides. The combination of these two new factors caused ships and fleets necessarily to be fought in a different manner from formerly—entailed, to use the technical word, new tactics. The innovations thus briefly mentioned, though equally radical, were much more gradual in their progress than those witnessed by our generation. The latter have occurred not merely within the lifetime but within the memory of many who are still among us. They are embraced, easily and entirely, within the reign of Queen Victoria. It has been said, plausibly, that if a naval officer who died half a century ago could revisit the earth he would find himself more at home in the ships of Elizabeth than in those of her present successor."}]}
{"messages": [{"role": "assistant", "content": "It has been said, plausibly, that if a naval officer who died half a century ago could revisit the earth he would find himself more at home in the ships of Elizabeth than in those of her present successor. No such sudden and sharp contrast troubled the seamen of the earlier era. It is true and interesting to note that the battle of Lepanto in 1573, although a few vessels of broadside type therein exercised a decisive influence, was fought chiefly by galleys, while in the contest with the Spanish Armada in the English Channel fifteen years later sailing ships played the leading part; but while the fact gives a valuable assistance to precision of memory by fixing an approximate date when the one type was definitely supplanted by the other, it remains that the turning-point thus indicated was reached long after cannon and sails first were used afloat, and that another century elapsed before the galley was definitively abandoned. BIRD’S-EYE VIEW OF THE TRANSITION \nA few dates will illustrate the swiftness of our recent transformations. In 1838, when the French navy reduced San Juan de Ulloa, the principal defence of Vera Cruz, and in 1840, in the British attack upon Acre, the fighting power was wholly in sailing ships such as had fought at Trafalgar thirty-five years before. Two small paddle steamers towed the French frigate into position, while the four British vessels of the same type contributed only a desultory addition to the broadsides of seven sailing ships of the line, which compelled the surrender of the fortress."}]}
{"messages": [{"role": "assistant", "content": "Two small paddle steamers towed the French frigate into position, while the four British vessels of the same type contributed only a desultory addition to the broadsides of seven sailing ships of the line, which compelled the surrender of the fortress. The first screw ship of the line in the British navy was launched in 1852; the last sailing ship of that class went out of commission in 1860. All alike, the ships of Vera Cruz and of Acre, and their short-reigning successors, the steam frigates and ships of the line, are now as much things of the past, in sails, in engines, and in guns, as are the galleys of Lepanto and the ships of the Armada. By 1870 it had been recognized everywhere that a type of vessel corresponding in essential features with the present armored battle-ships had displaced all competitors. The span of a single generation had seen the transition of the ships of Drake and Nelson to those of our own day. The career of Farragut was run in the intermediate period."}]}
{"messages": [{"role": "assistant", "content": "The career of Farragut was run in the intermediate period. His success for the most part was achieved and his renown won with vessels substantially of the older type, but with auxiliary steam-power. It is almost needless to remark that this seemingly abrupt transition is but one incident in the startling progress made during the century in all the arts of peace as of war. Like the others, it is due to an intellectual activity, greater probably than that of our predecessors, and directed since the peace of 1815 less upon external political interests than upon scientific investigation, and upon the application of the results to the improvement of processes of every kind. The changes in conception and in development of the instruments of naval warfare result from the increased power of dealing with refractory material which has been acquired by scientific and practical men in the laboratory and the workshop. Thus viewed, though so rapid in realization as to amount to a revolution, not only is the change seen to be the outcome of a long, though silent preparation, but it is brought also into its due relation to the general movement of the age, and found to share its special characteristics."}]}
{"messages": [{"role": "assistant", "content": "Thus viewed, though so rapid in realization as to amount to a revolution, not only is the change seen to be the outcome of a long, though silent preparation, but it is brought also into its due relation to the general movement of the age, and found to share its special characteristics. Our ancestors of the eighteenth century had their own problems, noble and absorbing, but chiefly political in character. While new worlds were being gathered into the embrace of European civilization, the leading powers struggling among themselves for pre-eminence in the work, and while the harvest was ripening for the French Revolution, science crept forward, but slowly and silently, the pre-occupation of the few, not the interest of the many. The object of the present article is to describe the type of war vessel prevalent universally among civilized nations when the nineteenth century opened, and to trace historically the sequence of ideas and of facts which have resulted in the type whose general acceptance is seen now in the practice of the chief naval states. SAILING SHIPS AND BROADSIDE BATTERIES \nWhen the nineteenth century began, the ships that contended for the control of the sea were, and for two centuries had been, sailing ships with broadside batteries: the guns, that is, were distributed along both sides from the bow to the stern on one, two, three, or four decks. From the largest down, all were of this type until the very smallest class was reached."}]}
{"messages": [{"role": "assistant", "content": "From the largest down, all were of this type until the very smallest class was reached. In the latter, which could scarcely be considered fighting ships, the gun power was at times concentrated into a single piece, which swept from side to side round the horizon, thus anticipating partially the modern turreted ironclad with its concentrated revolving battery. The arrangement of guns in broadside involved anomalies and inconveniences which seem most singular when first noted. A ship in chase of another, for instance, had no guns which threw straight ahead. If it were wished to fire, in order to cripple the fleeing enemy, it was necessary to deflect from the course; and in order to bring most of the guns on one side into play the vessel had to swing round nearly at right angles to the direction of pursuit. This, of course, lost both time and ground."}]}
{"messages": [{"role": "assistant", "content": "This, of course, lost both time and ground. Broadside fire—the distribution of guns in broadside—rests, however, upon an unchangeable condition, which controls now as it did a century ago. Ships then were from three to four times as long as they were broad; the proportion now is, length from four to six times the breadth—or beam, as it is technically called. Therefore, except in small vessels, where the concentration of the whole weight that can be carried in battery gave but one piece effective against a probable target, a full development of fire required the utilization of the long side of the ship rather than of its short cross-section. This is precisely analogous to the necessity that an army has of deploying into line, from any order of march, in order to develop its full musketry fire. The mechanical attainment of the last century did not permit the construction of single guns that would contain the weight of the whole battery of a big ship: but even had it, guns are not wanted bigger than will penetrate their target most effectively."}]}
{"messages": [{"role": "assistant", "content": "The mechanical attainment of the last century did not permit the construction of single guns that would contain the weight of the whole battery of a big ship: but even had it, guns are not wanted bigger than will penetrate their target most effectively. When an ounce of lead will kill a man it is useless to fire a pound. The limit of penetration once reached, it is numbers, not size, that tell: and numbers could be had only by utilizing the broadside. This condition remains operative now; but as modern battle-ships present two or more kinds of target—the heavy armored and that which is light armored, or unprotected—the application of the principle in practice becomes more complicated. Batteries now are necessarily less homogeneous than they once were, because targets vary more. DISAPPEARANCE OF BOW FIRE \nThe adoption of broadside batteries followed, therefore, necessarily upon increase of size and consequent length, but not upon that only."}]}
{"messages": [{"role": "assistant", "content": "DISAPPEARANCE OF BOW FIRE \nThe adoption of broadside batteries followed, therefore, necessarily upon increase of size and consequent length, but not upon that only. It is instructive to observe that the sailing fighting ship was derived, in part, at least, from the galley, and its resemblance in form to the latter is traceable for at least a century after the general disuse of the oar. As the galley, however, was small, it could concentrate its fire advantageously in one or two pieces, for which small number the cross-section offered a sufficient line of emplacement: and as, when it could move at all, it could move in any direction, there was a further advantage in being able to fire in the direction of its motion. Hence, bow fire prevailed in galleys to the end, although the great galleasses of Lepanto and the Armada had accepted broadside batteries in great part, and whenever the galley type has recurred, as on Lake Champlain during our Revolutionary War, bow fire has predominated. The sailing ship, on the contrary, was limited as to the direction in which she could move. Taking her as the centre of a circle, she could not steer directly for much more than half the points on the circumference."}]}
{"messages": [{"role": "assistant", "content": "Taking her as the centre of a circle, she could not steer directly for much more than half the points on the circumference. Bow fire consequently was much less beneficial to her, and, further, it was found that, for reasons not necessary to particularize, her sailing, steering, and manœuvring were greatly benefited by the leverage of sails carried on the bowsprit and its booms, projecting forward of the bow, where they interfered decisively with right-ahead fire. For all these reasons, bow fire disappeared and broadside fire prevailed; but the fundamental one to be remembered is the greater development of fire conferred by greater length. All ships—except the very small ones known as schooners, cutters, and gunboats—were broadside vessels, moved by canvas which was carried commonly on two or three masts; but into the particulars of the sails it is presumed readers will not care to enter. Being thus homogeneous in general characteristics, the ships of this era were divided commonly into three principal classes, each of which had subdivisions; but it was recognized then, as it is now in theory though too little in practice, that such multiplication of species is harmful, and our forerunners, by a process of gradual elimination, had settled down upon certain clearly defined medium types. The smallest of the three principal classes of fighting ships were called sloops-of-war, or corvettes."}]}
{"messages": [{"role": "assistant", "content": "The smallest of the three principal classes of fighting ships were called sloops-of-war, or corvettes. These had sometimes two masts, sometimes three; but the particular feature that differentiated them was that they had but one row of guns in broadside, on an uncovered deck. The offices discharged by this class of vessel were various, but in the apprehension of the writer they may be considered rightly as being above all the protectors or destroyers of commerce in transit. All ships of war, of course, contributed to this end; but the direct preying upon commerce, upon merchant ships, whose resisting power was small, was done most economically by small vessels of relatively small power. Having a given amount of tonnage to devote to commerce destroying, many small vessels are more effective than a few big ones of unnecessary force. Such being the nature of the attack, the resistance must be similar in kind."}]}
{"messages": [{"role": "assistant", "content": "Such being the nature of the attack, the resistance must be similar in kind. That is, a flock of merchant ships being liable to attack by many small adversaries, several small protectors would be more efficient than one or two large ones. Sloops-of-war served also as despatch vessels and lookouts of a fleet, but were less well adapted to this service than the frigate was. THE FRIGATE AND HER GUNS \nThis latter celebrated and favorite class of ship stood next in order of power above the corvette, with which it might also be said to have blended; for although in the frigate class there were two, or at the most three, rates that predominated vastly in numbers over all the rest, yet the name covered many differing degrees of force. The distinguishing feature of the frigate was that it carried one complete row of guns upon a covered deck—upon a deck, that is, which had another deck over it. On this upper or spar deck there were also guns—more or fewer—but lighter in weight than those on the covered deck, usually styled the main deck."}]}
{"messages": [{"role": "assistant", "content": "On this upper or spar deck there were also guns—more or fewer—but lighter in weight than those on the covered deck, usually styled the main deck. The two principal classes of frigates at the beginning of this century were the thirty-two-gun and the thirty-eight-gun. That is, they carried nominally sixteen or nineteen guns on each side; but the enumeration is misleading, except as a matter of comparison, for guns of some classes were not counted. Ships generally had a few more cannon than their rate implied. The United States thirty-two-gun frigate _Essex_, for example, carried at first twenty-six long twelves on the main deck, with sixteen carronades and two chase guns on the spar deck. Above these two classes came the forty-four-gun frigate, a very powerful rate, which was favored by the United States navy and received a development of strength then unprecedented."}]}
{"messages": [{"role": "assistant", "content": "Above these two classes came the forty-four-gun frigate, a very powerful rate, which was favored by the United States navy and received a development of strength then unprecedented. Being such as here described, the frigate was essentially, though not exclusively, the appendage of a fleet of line-of-battle ships. Wars are decided not by commerce destroying nor by raids, however vexatious, but by fleets and armies, by great organized masses—that is, by crushing, not by harassment. But ships of the line, to perform their function, must keep together, both when cruising and when on the field of battle, in order to put forth their strength in combination. The innumerable detached services that must be discharged for every great organized force need for a fleet to be done by vessels of inferior strength, yet so strong that they cannot be intercepted or driven off lightly by every whipper-snapper of an armed ship that comes along. Moreover, a fact not always realized, speed—speed to hasten on a mission, to overtake a foe, or to escape pursuit—depends upon size, masts that can carry sail and hold way amid heavy seas."}]}
{"messages": [{"role": "assistant", "content": "Moreover, a fact not always realized, speed—speed to hasten on a mission, to overtake a foe, or to escape pursuit—depends upon size, masts that can carry sail and hold way amid heavy seas. Hence the frigate, not the lighter sloop, was indicated for the momentous duties upon which depended the intelligence and the communications of the fleet. Such leading considerations are needed to be stated and to be kept in mind, for they affected the warfare of the last decade of the century quite as really as they did that of the first, and a paper would indeed be incomplete which confined itself to indicating points of difference of progress, so-called, and failed to recognize those essential and permanent conditions which time will never remove. Frigates and sloops have disappeared in name and form, in motive power and in armament. Their essential functions remain, and will remain while war lasts. DUTIES OF THE FRIGATE \nThe truth of this statement will be evident from a brief mention of the duties frigates actually used to perform."}]}
{"messages": [{"role": "assistant", "content": "DUTIES OF THE FRIGATE \nThe truth of this statement will be evident from a brief mention of the duties frigates actually used to perform. While attending the fleet, not merely a part of it, the frigates were thrown out far in advance and on each side, as cavalry on land scours the country towards or through which the army advances. The distance to which they would be thus detached would sometimes amount to one hundred or two hundred miles, and the absence to days, rejoining being assured by the assignment of a rendezvous, or by an adequate knowledge of the admiral’s intended movements. It will be recognized that when thus alone frigates might meet equal or superior forces, to resist or to escape from which both strength and speed were needed. An extreme and particular case of such service was the watching of an enemy’s port by one or more frigates, when they had to keep close to the entrance, although a fleet might be within. Again, frigates were placed in certain central positions, rendezvous known only to the superior officers, where they cruised steadily, having information as to the whereabouts of the fleet, or instructions for expected vessels."}]}
{"messages": [{"role": "assistant", "content": "Again, frigates were placed in certain central positions, rendezvous known only to the superior officers, where they cruised steadily, having information as to the whereabouts of the fleet, or instructions for expected vessels. They were there centres of intelligence, round which the movements of the whole body revolved. When the fleet was actually in touch with a hostile fleet, in pursuit, or when expecting battle, the frigates were placed between their own force and the enemy; nearer, however, to the latter, as the essential point was to keep knowledge of his whereabouts and probable intentions. Such a position was at times extremely exposed. The frigates had to avoid equally capture and being driven and shaken off; they must keep close, yet not be caught. When engagement ensued they passed through to the off side of their own fleet, where they were dispersed at intervals abreast the main line, like the file closers of a military line ashore."}]}
{"messages": [{"role": "assistant", "content": "When engagement ensued they passed through to the off side of their own fleet, where they were dispersed at intervals abreast the main line, like the file closers of a military line ashore. Here they fulfilled one special purpose, besides others. As the fleet fought with broadsides only, its ships were ranged one ahead of the other. Consequently signals made on the masts of the admiral could not be seen always by those ahead or astern of him; but the frigates in the other line made the same signals, “repeated,” as it was said, where they could be read more certainly. But frigates did also more hazardous work. They went to crippled ships of the line and towed them into other positions, into or out of fire, and at times the admiral summoned a frigate alongside to carry a message to some part of the battle."}]}
{"messages": [{"role": "assistant", "content": "They went to crippled ships of the line and towed them into other positions, into or out of fire, and at times the admiral summoned a frigate alongside to carry a message to some part of the battle. “I noticed,” says Marryatt, in one of his novels, “the look of pride on the faces of our officers when it appeared that the loss on board our frigate was greater than that of some of the ships in the line.” \nFor such offices it is evident there were wanted a strength and a weight which the corvette did not have. A corvette would make poor work of towing a heavy ship, and could not carry as surely the sail needed to maintain a position. At the same time it should be observed that excess of size above the requirements stated should be exceptional. In the opinion of the writer the forty-four-gun frigate in her day possessed a fighting force and a weight of body in excess of that required by the ordinary functions of her nominal class. For exceptional reasons, a few of the type were permissible in a large navy."}]}
{"messages": [{"role": "assistant", "content": "For exceptional reasons, a few of the type were permissible in a large navy. On the other hand, it may be inferred from the long experience of the British navy, and the resultant practice, that ships of twenty-eight, twenty-four, and twenty guns, though often styled frigates, were not found satisfactory as such. In the distribution of tonnage between size and numbers, a mean must be found; and it must be added that a just mean is a very different thing from a compromise. These considerations also apply to present-day problems. EARLY SHIPS OF THE LINE \nIn the fleet-ship, likewise the ship of the line, as the opening century styled the class of vessel known in the closing days as the battle-ship, our predecessors had reached a mean conclusion. The line-of-battle ship, or the ship of the line, as more usually called, differed from the frigate generically, in that it had two or more covered decks."}]}
{"messages": [{"role": "assistant", "content": "The line-of-battle ship, or the ship of the line, as more usually called, differed from the frigate generically, in that it had two or more covered decks. There were one or two cases of ships with four decks, but, as a rule, three were the extreme; and ships of the line were roughly classed as two or three deckers. Under these heads two-deckers carried in their two centuries of history from fifty to eighty-four guns; three-deckers from ninety to one hundred and twenty. The increase in number of guns, resulting, as it did, from increase of size, was not the sole gain of ships of the line. The bigger ships got, the heavier were their timbers, the thicker their planking, the more impenetrable, therefore, their sides. There was a gain, in short, of defensive as well as offensive strength, analogous to the protection given by armor."}]}
{"messages": [{"role": "assistant", "content": "There was a gain, in short, of defensive as well as offensive strength, analogous to the protection given by armor. “As the enemy’s ships were big,” wrote a renowned British admiral, “they took a great deal of drubbing.” \nBetween the great extremes of strength indicated by fifty and one hundred and twenty guns—whose existence at one and the same time was the evidence of blind historical development, rather than of intelligent relative processes—the navy of a century ago had settled upon a mean, to appreciate which the main idea and purport of the ship of the line must be grasped. The essential function of the ship “of the line” was, as the name implies, to act in combination with other ships in a line of battle. To do this was needed not only fighting power, but manœuvring ability—speed and handiness—and in order that these qualities might approach homogeneousness throughout the fleet, and so promote action in concert, the acceptance of a mean type was essential. To carry three decks of guns, a ship had to expose above water a side disproportionately high relatively to her length, her depth, and her hold upon the water. She consequently drifted rapidly when her side was turned to the wind; while, if her length was increased, and so her hold on the water, she needed more time and room to tack and to wear—that is, to turn around."}]}
{"messages": [{"role": "assistant", "content": "She consequently drifted rapidly when her side was turned to the wind; while, if her length was increased, and so her hold on the water, she needed more time and room to tack and to wear—that is, to turn around. Ships of this class also were generally—though not necessarily—slow. ADVANTAGES OF THE SEVENTY-FOURS \nThe two-decked ship was superior in speed and in handiness, and for that reason, even when acting singly, she could put forth such power as she possessed more quickly and more certainly. But these qualities were most conspicuously valuable when ship had to act with ship. The great secret of military success, concerted action in masses, was in the hands of the two-decked ship, because in her were united to the highest point individual power and facility for combined action. And this was true not only of two-deckers in general, but of the particular species known as the seventy-four-gun ship."}]}
{"messages": [{"role": "assistant", "content": "And this was true not only of two-deckers in general, but of the particular species known as the seventy-four-gun ship. Ships below that rate lacked individual fighting power. Ships above it, the eighty and eighty-four, lost manœuvring power because of their greater length and weight. Under the conditions of sail a fleet of seventy-fours could get out the whole power of the force more surely and more rapidly than the equivalent number of guns in ships of any other kind. Thus offensive power dictated its survival. To our own day it reads the lesson that offensive power, the _sine quâ non_ of a military organization, lies not merely in the greatest strength of the single ships, but in the uniformity of their action and rapidity of their movements, as conducive to the quick putting forth of the strength of the whole body at once and in mutual support."}]}
{"messages": [{"role": "assistant", "content": "To our own day it reads the lesson that offensive power, the _sine quâ non_ of a military organization, lies not merely in the greatest strength of the single ships, but in the uniformity of their action and rapidity of their movements, as conducive to the quick putting forth of the strength of the whole body at once and in mutual support. It may be asked naturally, why, then, were there any ships bigger or smaller than this favored type? For smaller, the answer is that short ships of lighter draught are best suited for shoal or intricate navigation. The shoals of Holland forbade heavy ships to the Dutch navy, materially reducing its fighting strength. Before France entered our Revolutionary struggle the British sent only sixty-fours to operate upon our comparatively shallow coasts and bars. As regards bigger ships, they were useful exceptionally, as were forty-four-gun frigates, and for the following reason: Every line of battle has three particularly dangerous points—the centre, because there the line, if pierced, divides into the two smaller fragments; and the flanks, or ends, because the extremities are supported less easily by the rest of the force than the centre is, one extremity being farther from the other than the centre is from either."}]}
{"messages": [{"role": "assistant", "content": "As regards bigger ships, they were useful exceptionally, as were forty-four-gun frigates, and for the following reason: Every line of battle has three particularly dangerous points—the centre, because there the line, if pierced, divides into the two smaller fragments; and the flanks, or ends, because the extremities are supported less easily by the rest of the force than the centre is, one extremity being farther from the other than the centre is from either. Such local weakness could not be remedied by the use of two ships, for, if the line were properly closed, one of them could fire at the enemy only through or over the other. The sole way of giving the strength there required was by concentrating it into individual ships, either by putting on the additional battery, which gives a three-decker, or by making the seventy-four heavier, resulting in an eighty-gun ship on two decks. These stronger vessels were, therefore, stationed in the centre or on the flanks of a line of battle. The particular functions, the _raison d’être_, of the three leading classes of ships of war—the sloop, the frigate, and the ship of the line—have now been stated. It remains to give an account of the chief features of the armament carried on their broadsides, as described."}]}
{"messages": [{"role": "assistant", "content": "It remains to give an account of the chief features of the armament carried on their broadsides, as described. BATTERIES SEVENTY-FIVE YEARS AGO \nWhen the nineteenth century began, batteries of ships were composed of two principal classes of guns: the long gun and the short gun, or carronade. The difference between these lay in the way the weight of metal allowed for each was utilized. The long gun, as its name implies, was comparatively long and thick, and threw a small ball with a heavy charge of powder. The ball, therefore, flew swiftly, and had a long range. A carronade of the same weight was short and comparatively thin, could use only a small charge of powder, lest it burst, and threw a large ball."}]}
{"messages": [{"role": "assistant", "content": "A carronade of the same weight was short and comparatively thin, could use only a small charge of powder, lest it burst, and threw a large ball. Its shot, therefore, moved slowly and had short range. Fired at a target—a ship’s side—within range of both guns, the shot from the long gun penetrated quickly, the wood had not time to splinter badly, and a clean hole was the result. The carronade’s shot, on the contrary, being both larger and slower, penetrated with difficulty, all the surrounding wood felt the strain and broke up into splinters, leaving a large jagged hole, if the shot got through. These effects were called respectively piercing and smashing, and are reproduced, in measure, upon targets representing the side of a modern ironclad. They have been likened familiarly to the effect of a pistol-ball and of a stone upon a window pane: the one goes through clean, the other crashes."}]}
{"messages": [{"role": "assistant", "content": "They have been likened familiarly to the effect of a pistol-ball and of a stone upon a window pane: the one goes through clean, the other crashes. The smashing of the carronades, when fully realized, was worse than penetration, and was greatly dreaded; but, on the other hand, a ship which feared them in an opponent might keep out of their range. This expedient was so effective that carronades, which did great damage until their tactics were understood, gradually fell into disfavor. Nevertheless, they remained in use till after the peace of 1815. In 1814 the battery of the U. S."}]}
{"messages": [{"role": "assistant", "content": "S. S. _Essex_ was chiefly carronades, and their inadequate range was a large factor in her defeat. At the period in question guns of all sorts fired only non-explosive projectiles, solid or hollow shot. The destructive shell of the present day was used only by pieces called mortars, in vertical firing, which will be spoken of farther on. Such were not mounted on the ships of the fleet generally, nor used against shipping, except when packed in a small harbor."}]}
{"messages": [{"role": "assistant", "content": "Such were not mounted on the ships of the fleet generally, nor used against shipping, except when packed in a small harbor. They did not enter into naval warfare proper. The ram and the torpedo of present warfare were unknown. On the other hand, there was practised a form of fighting which is thought now to have disappeared forever, namely, boarding and fighting hand-to-hand on the deck. Even then, however, boarding did not decide the main issue of a sea-fight, except occasionally in very small vessels. The deck of a large and fresh ship was not to be reached easily."}]}
{"messages": [{"role": "assistant", "content": "The deck of a large and fresh ship was not to be reached easily. Boarding was like the cavalry charge that routs a wavering line; the ship had been beaten at the guns before it occurred. The real fighting was done by the long guns and carronades disposed in the broadsides. Besides rapidity and precision of fire, always invaluable, the two opponents sought advantage of position by manœuvring. They closed, or they kept apart, according to their understanding of the other’s weight and kind of battery. Each tried, when possible, to lie across the bow or the stern of the enemy, for then his guns ranged from end to end of the hostile ship, while the latter’s broadside could not reply."}]}
{"messages": [{"role": "assistant", "content": "Each tried, when possible, to lie across the bow or the stern of the enemy, for then his guns ranged from end to end of the hostile ship, while the latter’s broadside could not reply. Failing this extreme advantage of position, the effort was made so to place one’s self that the opponent’s guns could not bear—for they swept only a few degrees before and abaft the broadside—while your own could. If this also was impossible, the contestants lay side to side at a greater or less distance, and the affair became an artillery duel. BRITISH AND FRENCH STYLES OF FIGHTING \nBesides these recognized advantages of position, there was also a question upon what part of the enemy the fire should be directed. In this there were two principal schools of tactics, one of which aimed at the hull, to break down the fire of the hostile ship and destroy her fighting men, while the other sought, by pointing higher, to cut away the sails, rigging, and masts, rendering the foe helpless. The latter, in general, was the policy of the French; the former, and, it may be affirmed, the more surely successful, was the practice of the British."}]}
{"messages": [{"role": "assistant", "content": "The latter, in general, was the policy of the French; the former, and, it may be affirmed, the more surely successful, was the practice of the British. The two schools find their counterpart in the tactical considerations which now affect the question of rapid-fire and of heavy guns, each of which has its appropriate target, covering in the latter case the motive power, in the former the personnel. These three leading classes of vessels, with their functions, armaments, and tactics of the single ship, as described, performed in their day and during the great maritime contests of two centuries all the duties that at any time can be required of a maritime fighting organization. By them the control of the sea in the largest sense was disputed and was determined; by them commerce was attacked, and by them it was protected. They themselves have passed away, but the military factors remain the same. The mastery of the sea and the control of its commerce—of which blockade is but a special case—are now and must remain always the chief ends of maritime war."}]}
{"messages": [{"role": "assistant", "content": "The mastery of the sea and the control of its commerce—of which blockade is but a special case—are now and must remain always the chief ends of maritime war. The ends continuing the same, the grand disposition of navies—their strategy—reposes upon the same principles that it ever did. Similarly, while the changes in the characteristics of ships will cause the individual vessel to be fought in manners different from its predecessors, the handling of masses of ships in battle—fleet tactics—must proceed on the same general principles as of old. The centre and the two extremities of all orders are always the points of danger; concentration upon one or two of the three, however effected, must be always the principle of action. These things, which cannot vary, form, therefore, no part of a paper which deals with changes. THEY HAD THEIR BREAK-DOWNS THEN, TOO \nThere should be added for the general public the caution that the difficulties, the imperfections, and the frequent halting state of ships-of-war in commission for sea service at the present day are no new things."}]}
{"messages": [{"role": "assistant", "content": "THEY HAD THEIR BREAK-DOWNS THEN, TOO \nThere should be added for the general public the caution that the difficulties, the imperfections, and the frequent halting state of ships-of-war in commission for sea service at the present day are no new things. To the naval historian familiar with the correspondence of the past they are the inevitable attendants of all government action, wherein the most economical methods are always dominated, historically, by considerations of expediency which are political in character. The necessity of keeping the public in good-humor, and of not laying open points upon which opposition can enlarge, induces apparent economies, which sacrifice not only economy, but the best results. This is a great evil, as yet apparently inseparable from public enterprises as distinguished from private ones. If any one supposes that the ships with which Great Britain overthrew Napoleon, and with which Nelson and his contemporaries won their as yet unparalleled victories, were always or generally in good material condition, he is greatly mistaken. What is different in our day, apparently, is a tendency in ships to rely for their repairs and material efficiency more upon dock-yards and workshops than upon their own resources, a disposition also to be unduly discouraged by imperfections in the motive enginery."}]}
{"messages": [{"role": "assistant", "content": "What is different in our day, apparently, is a tendency in ships to rely for their repairs and material efficiency more upon dock-yards and workshops than upon their own resources, a disposition also to be unduly discouraged by imperfections in the motive enginery. War will correct this or war will fail. In maintaining efficiency while keeping the sea, quite as much as in fighting skill, lay the supreme excellence of officers like Nelson and Jervis. Men now ought to appreciate better than they do what difficulties of this sort seamen underwent a hundred years ago and how they refused to yield to them. “The difference between myself and the French marshals,” the Duke of Wellington is reported to have said, “was as when a man starts on a journey with a new harness. What if something gives way, as in war something is sure to go wrong?"}]}
{"messages": [{"role": "assistant", "content": "What if something gives way, as in war something is sure to go wrong? Shall you stop or go back for a workman? Not so; hitch up the break with a bit of rope, or whatever comes handy, and go on. That is what I did.” \nThe succession of cause and effect which has produced the present ship-of-war will be traced in rapid outline, in order to leave as much room as may be for the description of the essential feature of the ship herself as she now exists. Two chief factors concur to a ship-of-war—motive power and fighting power. The displacement of sails by engines, and the progressive development of the latter, are features of the general progress of the century."}]}
{"messages": [{"role": "assistant", "content": "The displacement of sails by engines, and the progressive development of the latter, are features of the general progress of the century. The engines of a ship-of-war are differentiated from those of merchant ships chiefly by the necessity of protection. This affects their design, which must be subordinated to the requirement of being as far as possible below the water-line. The further great protection now afforded is incident rather to the use and development of armor as a part of the fighting power. Fighting power divides into offensive and defensive. Armor now represents the latter."}]}
{"messages": [{"role": "assistant", "content": "Armor now represents the latter. The fighting ship in every age is the product of the race between the two, and in the nineteenth century this was unprecedented in the ground covered and in the rapidity of the pace, due to the increased power of dealing with materials, already alluded to. CONTEST OF ARMOR AND PROJECTILE \nThe modern contest began with the introduction of horizontal shell fire in the third decade of the century. This term must be explained. It has been said that all ships’ guns up to 1815 threw non-explosive projectiles. In practice this is true; although Nelson alludes to certain shell supplied to him for trial, which he was unwilling to use because he wished not to burn his prizes, but to take them alive."}]}
{"messages": [{"role": "assistant", "content": "In practice this is true; although Nelson alludes to certain shell supplied to him for trial, which he was unwilling to use because he wished not to burn his prizes, but to take them alive. A shell is a hollow projectile filled with powder, the idea of which is that upon reaching the enemy it will burst into several pieces, each capable of killing a man, and the flame not impossibly setting woodwork on fire. It was necessary that the powder within should not explode from the combustion of the cartridge of the gun, for if it did its force, combined with the latter, might burst the gun; yet the process that should result in bursting must begin at that moment or else it would not take place at all. This difficulty was met by a short column of hard, compressed powder called the fuse, which extended from the outside to the inside of the shell. The outer end was inflamed by the charge of the gun, but from its density it burned slowly, so that the charge of the shell was not enkindled for five, ten, or more seconds. This expedient was in use over a century ago; but owing to imperfections of manufacture, no certainty was attained that the fuse might not be driven in or broken by the force of the discharge, or the shell itself be cracked and so explode prematurely."}]}
{"messages": [{"role": "assistant", "content": "This expedient was in use over a century ago; but owing to imperfections of manufacture, no certainty was attained that the fuse might not be driven in or broken by the force of the discharge, or the shell itself be cracked and so explode prematurely. Shell, therefore, were fired with very light charges; and, to obtain sufficient range—go far enough—they were used in very short, very thick guns, called bombs or mortars, to which great elevation was given. Such firing, because the shell flew high in the air, was called vertical firing, in contradistinction to the fire of the long gun or carronade, called horizontal fire because their projectiles rose little above the level. The destructiveness of shell from ordinary guns was so obvious, especially for forts to use against wooden ships, that the difficulties were gradually overcome, and horizontal shell fire was introduced soon after the cessation of wars allowed men time for thought and change. But although the idea was accepted and the fact realized, practice changed slowly, as it tends to do in the absence of emergency. In the attack on Vera Cruz, in 1848, Farragut was present, and was greatly impressed, as with a novelty, by the effect of what he called the “shell shot,” a hybrid term which aptly expresses the transition state of men’s minds at the time."}]}
{"messages": [{"role": "assistant", "content": "In the attack on Vera Cruz, in 1848, Farragut was present, and was greatly impressed, as with a novelty, by the effect of what he called the “shell shot,” a hybrid term which aptly expresses the transition state of men’s minds at the time. I remember an officer who entered the navy in 1840 telling me the respectful awe and distrust with which his superiors then regarded the new weapon, a very few of which for each gun were supplied tentatively. Ten years more, however, saw a great change, and in 1853 the attack of the Russian squadron of wooden sailing-ships upon the Turkish vessels in the Bay of Sinope gave an object-lesson that aroused the naval world to what wooden ships must expect from horizontal shell fire. In a few minutes three out of seven Turkish frigates were in flames; while of nine sailing-ships and two steamers only one of the latter escaped. HORIZONTAL SHELL FIRE \nThe Crimean War followed quickly, and in 1854 the wooden steamships of the line of the allies, vessels identical in fighting characteristics with those of Trafalgar, attempted to silence masonry works at Sebastopol. Though the disaster was not so great, the lesson of Sinope was reaffirmed."}]}
{"messages": [{"role": "assistant", "content": "Though the disaster was not so great, the lesson of Sinope was reaffirmed. Louis Napoleon, a thoughtful man though scarcely a man of action, had foreseen the difficulty, and had already directed the construction of five floating batteries which were to carry armor. Before the war ended these vessels attacked the forts at Kinburn, which they compelled to surrender, losing, themselves, no men except by shells that entered the gun ports. Their armor was not pierced. Horizontal shell fire had called for iron armor, and the two, as opposing factors, were now established in the recognition of men. The contest between the two sums up the progression and the fluctuations of military ideas which have resulted in the battle-ship of to-day, which, as the fleet-ship, remains the dominant factor in naval warfare, not only in actual fact but in present probability."}]}
{"messages": [{"role": "assistant", "content": "The contest between the two sums up the progression and the fluctuations of military ideas which have resulted in the battle-ship of to-day, which, as the fleet-ship, remains the dominant factor in naval warfare, not only in actual fact but in present probability. From the first feeble beginnings at Kinburn to the present time, although the strife has waxed greatly in degree, it remains unchanged in principle and in kind. To exclude the shell, because, starting as one projectile, it became many after penetration, in what does it differ from excluding the rapid-fire gun, whose projectiles are many from the first, and penetrate singly? There occurred, however, one singular development, an aberration from the normal line of advance, the chief manifestation of which, from local and temporary conditions, was in our own country. This was the transient predominance of the monitor type and idea; the iron-clad vessel, with very few very heavy guns, mounted in one or two circular revolving turrets, protected by very heavy armor. The monitor type embodied two ideas."}]}
{"messages": [{"role": "assistant", "content": "The monitor type embodied two ideas. The first was the extreme of defensive power, owing to the smallness of the target and the thickness of its armor—the hull of the vessel rising but little above the water—the turret was substantially the only target. The second was an extreme compression of offensive power, the turret containing two of the heaviest guns of the day, consequently guns of the heaviest penetration, which could fire, not in one direction, nor in several, but in all directions as the turret revolved, and which were practically the sole armament of the ship. The defensive power of the monitor was absolute up to the extreme resisting endurance of its armor. Its offensive power must be considered relatively to the target to which its guns were to be opposed. If much in excess of that target’s resistance, there was waste of power."}]}
{"messages": [{"role": "assistant", "content": "If much in excess of that target’s resistance, there was waste of power. Actually in our Civil War monitors were opposed to fortifications, except in one or two instances when they had to contend with the imperfect structures which the Confederates could put afloat. The target, therefore, was not in excess of their gun power. Moreover, being for coast warfare, the monitor then was necessarily of small draught and small tonnage. Her battery weight, therefore, must be small, and consequently lent itself to concentration into two guns, just as the battery weight of a schooner a century since found its best disposition in one long traversing gun. This was the infancy period of the iron-clad ship."}]}
{"messages": [{"role": "assistant", "content": "This was the infancy period of the iron-clad ship. The race between guns and armor was barely begun, and manufacturing processes still were crude. As these improved, with astounding rapidity, the successful production of rifled cannon of ever-increasing dimensions and penetrative force imposed an increased armor protection, which at the first was obtained chiefly by an increase of thickness, _i.e._, of weight. As guns and armor got heavier, ships had to be bigger to carry them, and, if bigger, of course longer. But the monitor idea, admirably suited to small ships, had now fast hold of men’s minds—in England especially, for the United States lapsed into naval somnolence after the war—and it was carried irreflectively into vessels of huge dimensions whose hulls rose much above the water. Weight for weight, the power of the gun outstripped the resistance of armor, and it soon became evident that even in a large ship perfect protection could be given only to a part of the structure."}]}
{"messages": [{"role": "assistant", "content": "Weight for weight, the power of the gun outstripped the resistance of armor, and it soon became evident that even in a large ship perfect protection could be given only to a part of the structure. Passing over intermediate steps, the extreme and final development of the monitor idea was reached in the _Inflexible_, planned in 1876 by the British Admiralty, built in the following years, and still in service. This vessel was of eleven thousand eight hundred and eighty tons displacement. She was three hundred and twenty feet long, and of that length only the central one hundred and ten feet had protection, but that was by armor two feet thick, while armored partitions extended from each end of this side belt across the vessel, forming a box one hundred and ten feet long by seventy-four broad. Within this box were two turrets, each with sixteen inches of armor, and carrying two guns which threw a shell of a ton weight. THE COMING OF THE MONITOR \nThe first monitor has been called an epoch-making ship, for she began an era."}]}
{"messages": [{"role": "assistant", "content": "THE COMING OF THE MONITOR \nThe first monitor has been called an epoch-making ship, for she began an era. The _Inflexible_ was also epoch-making, for she closed the era of the monitor pure and simple. Upon a development of three hundred and twenty feet of length she carried only four guns, of which it is not too much to say that their power was very far in excess of almost all targets that could be opposed to them. If, indeed, her possible opponents could have carried such an armor as her own all over their exposed surface, her guns would have been no heavier than needed, and the fewness must be accepted; but this was not the case. Like herself, ships of twelve thousand tons must have a penetrable target far exceeding in surface the almost impregnable box she presented. The unreasonableness of the result struck men at once, though of course she had advocates."}]}
{"messages": [{"role": "assistant", "content": "The unreasonableness of the result struck men at once, though of course she had advocates. As an exception, such a ship might pass; as a type, never. It was pointed out that guns of very small power could pierce the exposed ends about the water-line, and that, as water entered by numerous holes, she would not only sink lower, but for constructional reasons, not necessary here to give, she would lose stability rapidly—become liable to overset. If under such conditions she attempted to turn round, the inclination vessels take in so doing would be enough alone to cause her to capsize. Her defenders did not deny this; but they said that the likelihood of her exposed ends being so riddled was too slight to justify alarm. Under artillery conditions, then, this reply was plausible, though it soon ceased to be so."}]}
{"messages": [{"role": "assistant", "content": "Under artillery conditions, then, this reply was plausible, though it soon ceased to be so. Even then, however, it was true that a ship with only four guns that fired very slowly, and with such an exposed surface, was liable to serious injury from a nimble antagonist firing many guns rapidly. The defensive weakness of the _Inflexible_ is apparent; her offensive power, great as in the aggregate it was, was much impaired by lack of proper development, by undue compression into very few guns, the larger part of whose effect was wasted, except in the rare instances when they struck a target not often to be encountered. But this was not the only deduction from her strength through the excess of concentration. Very large guns fire very slowly, yet they are as subject to inaccuracy from the motion of the ship as is the smallest piece. Where the target is missed, it is immaterial whether the shot weighs a ton or a pound; and a gun that fires ten times to another’s once has ten times the chance of hitting."}]}
{"messages": [{"role": "assistant", "content": "Where the target is missed, it is immaterial whether the shot weighs a ton or a pound; and a gun that fires ten times to another’s once has ten times the chance of hitting. It is evident, therefore, taking the _Inflexible_ as she was, that a ship of the same weight and length with ten guns in broadside—twenty altogether—and with similar armor over her engines only, would have at the least a fair chance against the _Inflexible_, and would be much more efficient against vessels with average armor. Each of her ten guns firing once a minute, while the _Inflexible’s_ cannon required five minutes for discharge, would give over ten shots to one. CRITICISM OF THE _INFLEXIBLE_ \nWhile the _Inflexible_ was building there was born the idea whose present maturity enforces the abandonment of the pure monitor, except for vessels comparatively small and for special purposes. Machine guns, the Gatling, and the mitrailleuse were already known, and the principle was being applied to throw projectiles of a pound weight and over, which were automatically loaded and fired, requiring only to be aimed. Upon these followed the rapid-fire gun, of weight greatly exceeding theirs, the principle of which may be said to be that it is loaded by hand, but with ammunition so prepared and mechanism for loading so simple and expeditious as to permit a rate of firing heretofore unparalleled."}]}
{"messages": [{"role": "assistant", "content": "Upon these followed the rapid-fire gun, of weight greatly exceeding theirs, the principle of which may be said to be that it is loaded by hand, but with ammunition so prepared and mechanism for loading so simple and expeditious as to permit a rate of firing heretofore unparalleled. The highest extension of this principle is reached in the five-inch gun, up to which size the cartridge and the projectile make a single package called fixed ammunition, which is placed by one motion. Together they weigh ninety-five pounds, about as much as an average man can handle in a seaway, the projectile itself weighing fifty pounds. There are, it is true, six-inch rapid-fire guns, but in them the cartridge and shell are placed separately, and it is questionable whether such increase of effect, through greater weight, as they give is not gained at a loss of due rapidity. The _Inflexible_ exemplified in an extreme form the elements of offensive and defensive strength and weakness. Four guns of enormous calibre and no other battery, except pieces so light as to be useless against the thinnest armor, an impenetrable wall, covering a very limited area, and the remainder of the hull exposed, to be cut to pieces by a battery of numerous light cannon."}]}
{"messages": [{"role": "assistant", "content": "Four guns of enormous calibre and no other battery, except pieces so light as to be useless against the thinnest armor, an impenetrable wall, covering a very limited area, and the remainder of the hull exposed, to be cut to pieces by a battery of numerous light cannon. When to the latter the rapid-fire idea was successfully applied, multiplying their efficiency three or fourfold, her position, as an example to be followed, became untenable. The monitor idea, which refused to utilize the broadside for developing fire, and aimed chiefly at minimizing the target, evidently needed qualification after a certain moderate limit of size was passed; and that limit of size was when the entire weight of battery the ship could carry sufficed only for two, or, at the most, four guns of power great enough to pierce heavy armor. Strictly, in the opinion of the writer, the monitor type should not prevail beyond the size that can bear only one turret. In the strife of guns with armor, therefore, increase of power in guns, outstripping continually the increase of resistance in armor, called for bigger ships to bear the increased armor weight, till the latter could not possibly be placed all over the ship’s body. Hence the exposed target, upon which plays the smaller battery of rapid-fire guns."}]}
{"messages": [{"role": "assistant", "content": "Hence the exposed target, upon which plays the smaller battery of rapid-fire guns. To comprehend fundamentally the subsequent development, we must recur to the rudimentary idea that a ship of war possesses two chief factors, motive force and fighting force, the latter being composed of guns mainly and of men. Corresponding to these two chief powers there were of old, and there are still, two vulnerable elements, two targets, upon one or the other of which hostile effort logically and practically must be directed. A century ago the French, aiming at sails and spars, sought the destruction of the motive force; the British directed their fire upon the guns and men. In strict analogy now, the heavy guns seek the motive power, over which the heaviest armor is concentrated; the rapid-fire guns, searching the other portions of the ship, aim at the guns and men there stationed. BATTLE-SHIPS OF THIS DAY \nThe logical outcome of these leading ideas is realized in the present battle-ships as follows: There are two turrets, protected by armor, the thickest that can be given them, considering the other weights the ship has to carry, and of the highest resisting quality that processes of manufacture can develop."}]}
{"messages": [{"role": "assistant", "content": "BATTLE-SHIPS OF THIS DAY \nThe logical outcome of these leading ideas is realized in the present battle-ships as follows: There are two turrets, protected by armor, the thickest that can be given them, considering the other weights the ship has to carry, and of the highest resisting quality that processes of manufacture can develop. Armor of similar character and weight protects the sides about the engines. In each turret are guns whose power corresponds to the armor which protects them. Their proper aim—not, of course, always reached—is the heavy armored part of the enemy, chiefly the engines, the motive power. When they strike outside of this target, as often must happen, there is excess of blow, and consequent waste. The turrets are separated, fore and aft, by a distance as great as possible, to minimize the danger of a single shot or any other local incident disabling both."}]}
{"messages": [{"role": "assistant", "content": "The turrets are separated, fore and aft, by a distance as great as possible, to minimize the danger of a single shot or any other local incident disabling both. The fact that the ends of ships, being comparatively sharp, are less waterborne and cannot support extreme weights, chiefly limits this severance of the turrets. Between the two, and occasionally before or abaft them, is distributed the broadside rapid fire of the ship, which in its development is in contradistinction to the compressed fire of the monitor. This fire is rapid because the guns are many and because individually they can fire fast. Thus, the turret gun, twelve or thirteen inch in bore, fires once in five minutes; the five-inch rapid-fire gun thrice in one minute. The rapid-fire battery aims outside of the heaviest armor."}]}
{"messages": [{"role": "assistant", "content": "The rapid-fire battery aims outside of the heaviest armor. When it strikes that, unless it chance to enter a gun port, its effect is lost; but as much the greater part of the ship is penetrable by it, the chance of wasting power is less than in the case of the heavier guns. As most of a ship’s company are outside the protection of the heaviest armor, the rapid-fire gun aims, as did the British in the old line-of-battle ship, at the personnel of the enemy. The reader will comprehend that in the application of these leading ideas there is considerable variety in detail. The two turrets may be looked upon at present as the least variable factor; and in disposing armor all practice agrees that the turrets and engines receive the greatest protection. But how to distribute the total available weight of armor gives rise to varieties of practice which find their reflection in similar variety in the sizes and numbers of the rapid-fire guns, to whose penetrative force there is a corresponding thickness of armor."}]}
{"messages": [{"role": "assistant", "content": "But how to distribute the total available weight of armor gives rise to varieties of practice which find their reflection in similar variety in the sizes and numbers of the rapid-fire guns, to whose penetrative force there is a corresponding thickness of armor. For example, two battle-ships now building for the United States navy have four thirteen-inch guns in turrets, and in broadside fourteen five-inch, twenty six-pounder, and six one-pounder rapid-fire guns; between the two classes they have four eight-inch guns, also mounted in smaller turrets, superimposed on the main turrets. A ship since designed will have the same thirteen-inch gun fire, but in place of the eight-inch and five-inch will have fourteen six-inch rapid-fire guns. An expert officer, discussing these, says: “In the former the weight of fire per minute is two thousand and fifty pounds on the broadside and five hundred ahead or astern, while with the latter plan it is only one thousand seven hundred and fifty on the broadside and five hundred ahead and astern. But the main objection to the second plan is that the volume of effective fire is enormously diminished by the omission of eight-inch guns. The larger area covered with their armor is fairly safe from the six-inch gun at fighting ranges, whereas the eight-inch projectile at any range, and at even a considerable angle of incidence, will penetrate it.” In the judgment of the present writer the weight of this argument depends upon what is behind the armor the eight-inch only will penetrate."}]}
{"messages": [{"role": "assistant", "content": "The larger area covered with their armor is fairly safe from the six-inch gun at fighting ranges, whereas the eight-inch projectile at any range, and at even a considerable angle of incidence, will penetrate it.” In the judgment of the present writer the weight of this argument depends upon what is behind the armor the eight-inch only will penetrate. If battery and men, it is strong, if not decisive; if motive power only, not. HISTORY’S TEACHING AND THE FUTURE \nThe object of this paper has been not to present an accumulation of details, but to elucidate the principles upon which the details rest. The latter, when correct, are but the application of principles to practice. Subject to the imperfections attendant on all human work, the writer is persuaded that the greatest errors in practice—and especially the lack of homogeneousness which characterizes the present battle-ships—arise chiefly from the failure to refer back to principles. Until war has given us the abundant experience which led our predecessors to the broadside seventy-four as the rule, with occasional exceptions, we must depend upon reasoning alone for the solution of our problems; and the reasoner keeps within the limits of safety only by constant reference to fundamental facts."}]}
{"messages": [{"role": "assistant", "content": "Until war has given us the abundant experience which led our predecessors to the broadside seventy-four as the rule, with occasional exceptions, we must depend upon reasoning alone for the solution of our problems; and the reasoner keeps within the limits of safety only by constant reference to fundamental facts. The one experience of war which ships really contemporary have had was in the battle of the Yalu. Its teachings lose some value from the fact that the well-drilled Japanese used their weapons to advantage, while the Chinese were ill trained; still, some fair inferences can be made. The Japanese had a great many rapid-fire guns, with few very heavy ones, and their vessels were not battle-ships properly so-called. The Chinese, besides other vessels, had two battle-ships with heavy armor and heavy guns. Victory remained with the Japanese."}]}
{"messages": [{"role": "assistant", "content": "Victory remained with the Japanese. In the opinion of the writer two probable conclusions can be reached: That rapid-fire guns in due proportion to the entire battery will beat down a ship dependent mainly upon turret guns; that is, between two ships whose batteries are alike the issue of the contest will depend upon the one or the other gaining first a predominance of rapid fire. That done, the turret guns of the predominant ship will give the final blows to the engines and turrets of the other, whose own turret guns cannot be used with the necessary deliberation under the preponderant storm of projectiles now turned upon them. The other conclusion, even more certain than the first, is that rapid-fire guns alone, while they may determine an action, cannot make it decisive. Despite the well-established superiority of the Japanese rapid fire in that action, the Chinese battle-ships, though overborne, were not taken. Their heaviest armor being unpierced, the engines and turret guns remained effective, and they withdrew unmolested."}]}
{"messages": [{"role": "assistant", "content": "Their heaviest armor being unpierced, the engines and turret guns remained effective, and they withdrew unmolested. BATTLE-SHIPS THAT ARE TOO LARGE \nThe battle-ship constituted as described remains for the present the fighting ship upon which the issues of war will depend. The type is accepted by all the leading naval states, though with considerable variations in size. As regards the latter feature, the writer believes that the enormous tonnage recently given is excessive, and that the reasons which support it, too numerous and various to be enumerated at length, have the following fundamental fault: they look too much to the development of the individual ship and too little to the fact that the prime requisite of the battle-ship is facility for co-operating with other ships of its own type—facility in manœuvring together, facility in massing, facility also in subdividing when occasion demands. It may be remarked, too, that the increase of size has gone much more to increase of defensive power than of offensive—a result so contrary to the universal teachings of war as of itself to suggest pausing. Does the present hold out any probabilities of important changes in the near future, of revolutionary changes?"}]}
{"messages": [{"role": "assistant", "content": "Does the present hold out any probabilities of important changes in the near future, of revolutionary changes? No. For twenty-five or thirty years now we have been expecting from the ram and from the torpedo results which would displace the gun from its supremacy of centuries. Those results, however, are not yet visible. No one disputes the tremendous effects of the ram and of the torpedo when successfully used; but I believe I am correct in saying that the great preponderance of professional opinion does not attribute to them a certainty, or an approach to certainty, impairing the predominance of the gun. This is not the conclusion of mere conservation in a profession naturally conservative."}]}
{"messages": [{"role": "assistant", "content": "This is not the conclusion of mere conservation in a profession naturally conservative. The fluctuations of professional opinion have been sufficiently marked and the matter sufficiently argued to dispose of that contention. Nor is this supremacy of the gun probably a transient matter, liable to pass away with improvements greater than those of the last quarter of a century. The advantage of the gun depends upon conditions probably permanent—upon its greater range, its greater accuracy, its greater rapidity. The individual effect of each shot may be less than that of a torpedo or of a ram thrust; but, as was said in comparing very heavy guns with rapid fire, the probability of many hits prevails over the possibilities of one great blow. THE GUN AND THE TORPEDO \nIn none of these features is either of the other weapons likely to overtake the gun."}]}
{"messages": [{"role": "assistant", "content": "THE GUN AND THE TORPEDO \nIn none of these features is either of the other weapons likely to overtake the gun. The torpedo relies mainly upon stealth, the ram mainly upon a happy chance for effective use. Both stealth and chance have their place in war; stratagem and readiness, each in place, may contribute much. But the decisive issues of war depend upon the handling of masses with celerity and precision, according to certain general principles of recognized universality. Afloat, such massed force, to be wielded accurately and rapidly, must consist of units not too numerous because of their smallness—as torpedo craft would be—nor too unwieldy because of their size. We may not be able to determine yet, in advance of prolonged experience of war, just what the happy mean may be corresponding in principle to the old seventy-four, but we may be reasonably sure that it will be somewhere in the ranks of the present battle-ships; and that in the range, accuracy and rapidity of their gun-fire—especially when acting in fleets—will be found a protection which the small vessels that rely upon the torpedo or ram alone will not be able to overcome, though they may in rare instances elude."}]}
{"messages": [{"role": "assistant", "content": "We may not be able to determine yet, in advance of prolonged experience of war, just what the happy mean may be corresponding in principle to the old seventy-four, but we may be reasonably sure that it will be somewhere in the ranks of the present battle-ships; and that in the range, accuracy and rapidity of their gun-fire—especially when acting in fleets—will be found a protection which the small vessels that rely upon the torpedo or ram alone will not be able to overcome, though they may in rare instances elude. Concerning the frigates and sloops of our predecessors, their place is now taken, and their duties will be done, by the classes of vessel known generically as cruisers, protected or unprotected. The protection, the defensive element of strength, has reference mainly to the engines, to the motive power. The battery, the offensive factor, tends upon the whole to revert more and more to the development of fire, to utilizing the length of the vessel by multiplying the number of guns and diminishing their individual size; and the tendency is increased by the fact that, as such ships are expected to fight only vessels of their own kind, their probable target is penetrable by light guns. Speed is the great element in the efficiency of cruisers, and whatever the speed in smooth water, a great advantage inures to larger ships in heavy winds and seas. As for “armored” cruisers, of which there are many, they belong rather to the class of battle-ships than of cruisers."}]}
{"messages": [{"role": "assistant", "content": "As for “armored” cruisers, of which there are many, they belong rather to the class of battle-ships than of cruisers. Whatever the advantages of the particular ships, the name suggests a regrettable confusion of purpose, and, in practice, a still more regrettable departure from homogeneity. A. T. MAHAN. LITERATURE \n\n“Time and space,” a noble philosopher has observed, “are but hallucinations.” It may be so, and from the point of view of the metaphysician ours may have been merely a “so-called nineteenth century.” Certain it is that to judge literature in blocks of centuries is to make a convenient but illogical cross-division."}]}
{"messages": [{"role": "assistant", "content": "LITERATURE \n\n“Time and space,” a noble philosopher has observed, “are but hallucinations.” It may be so, and from the point of view of the metaphysician ours may have been merely a “so-called nineteenth century.” Certain it is that to judge literature in blocks of centuries is to make a convenient but illogical cross-division. The early, and perhaps the most important, literary influences of the century were in existence long before 1801. Thus, if we look at whatever is now called _fin de siècle_, at violent antagonism to tradition and convention, at discontent of every sort with everything—with rank, wealth, morality, law, marriage, the family—we find that this passion was as noisy and self-complacent a hundred years ago as it is to-day. The French Revolution was the lurid playground of “New Women,” full of what they supposed to be new ideas. The German drama of 1780–1800, now best remembered by the parody called “The Rovers,” in the _Anti-Jacobin_, was replete with the humorless paradoxes and strained situations of Ibsen. The shortest way to an understanding of the antiquity of our “new ideas” is, in fact, a study of the Poetry of the _Anti-Jacobin_."}]}
{"messages": [{"role": "assistant", "content": "The shortest way to an understanding of the antiquity of our “new ideas” is, in fact, a study of the Poetry of the _Anti-Jacobin_. Romance, again, as far as romance depends for her effects on desperate deeds, on the rhetoric of noble brigands, on the phantasms of the sheeted dead shivering down dark passages among skeletons, on clanking chains, and on distressed damsels, was as much alive in the end of the eighteenth century as at any age of literary history. Goethe, Schiller, Bürger, Mrs. Radcliffe, all following in the Gothic wake of honest Horace Walpole and his _Castle of Otranto_, were preparing the ground for Scott and Dumas. Once more the old “popular” elements so necessary to literature (which, like Antæus, regains vigor on touching mother-earth) had been wholly absent from the poetry and prose of the last reigning Stuart and of the first two Hanoverian kings of England. But, about 1770–1780, literature had returned to its archaic popular sources."}]}
{"messages": [{"role": "assistant", "content": "But, about 1770–1780, literature had returned to its archaic popular sources. Percy had made _volks-lieder_ fashionable, Fergusson and Burns had revived the rustic muse of Scotland, and Macpherson had given mankind a draught, though an adulterated draught, from the cup of the sorceries of the Celtic enchantress. In opposition to the urban self-restraint and contented complacency of the Augustan age, Rousseau had preached the pleasures of virtue, sentiment, and of a “blessed state of Nature”; young Werther had gotten him a stool to be sad upon, like Master Stephen: weeping was the mode. Rousseau, as Mr. Pater once observed in conversation, was “the grandmother of us all,” and as tearful as Mrs. Gummidge in _David Copperfield_."}]}
{"messages": [{"role": "assistant", "content": "Gummidge in _David Copperfield_. Meanwhile the “emancipation” born of science had set in; people thought they knew all about everything; the elder Darwin could explain the universe without a God, quite as easily as any modern Darwinian, if not so elaborately. He may not have been always correct in his theories and facts, still, there they were, and they were “emancipating.” Yet, far from being laughed out of court by the gratifying progress of science, a more mystical religion and a life more austere had come in from the preaching of Wesley, who was practically the parent of our neo-Catholicism in its varying forms. The “Oxford Movement,” with all the strange after-symptoms which it has left behind it, is directly descended from Wesley. Thus romance, sentiment, freedom and variety in poetic form, philanthropy, revolt against the past, return to and reverence for the past, scientific doubt, weariness of life, love of nature, wistful belief, relapse on the forms of the Church, and everything else which stamps the literature of the nineteenth century were alive and active in the last half of the eighteenth century. The year 1801 made no sudden break."}]}
{"messages": [{"role": "assistant", "content": "The year 1801 made no sudden break. The nineteenth century merely went on evolving the principles, revolutionary or reactionary, of the last half of the eighteenth century. Thus Crabbe, the precursor of whoever, Englishman, American, Frenchman, or Slav, has written of the sombre tragedies of the poor, was born in 1754. Blake, whose perfectly un-Augustan rhapsodies and mystic lyrics were made fashionable about 1870, was born in 1757, out of due time, for his best side is Elizabethan in quality. Burns, born in 1759, is as much at home in the nineteenth century as Tolstoï, while Godwin could not be more “advanced,” or Mary Wollstonecraft more of “a New Woman,” if the former belonged to our “Forward Liberals” and the latter perorated at congresses of her sex. The first twenty-five years of Miss Austen belong to the eighteenth century; yet, except for a certain “old-fashioned” primness of style, she is the first, and, beyond all doubt, the greatest of all nineteenth-century “realistic” novelists of domestic life."}]}
{"messages": [{"role": "assistant", "content": "The first twenty-five years of Miss Austen belong to the eighteenth century; yet, except for a certain “old-fashioned” primness of style, she is the first, and, beyond all doubt, the greatest of all nineteenth-century “realistic” novelists of domestic life. For, though a “realist,” she is a humorist, and the combination is almost unexampled. Your common realist is a gloomy thing, with no more sense of the comic than M. Zola. Of the new poets, revolutionary in metre and matter, Wordsworth, Scott, Coleridge, and Southey were born in 1770–1774; they were mature before the nineteenth century dawned. His northern home, among the hills and lakes, fitted Wordsworth to be the austere and mystical poet of nature and of man in relation to nature."}]}
{"messages": [{"role": "assistant", "content": "His northern home, among the hills and lakes, fitted Wordsworth to be the austere and mystical poet of nature and of man in relation to nature. Born a poet, his genius was determined by his environment, while his ardent sympathy with the Revolution at once turned his attention to the unregarded poor, and inspired his not wholly successful attempt to shake off the trammels of Augustan “poetic diction,” the survival of the Latinism of Boileau and Pope. Later, of course, Wordsworth became the Tory, the patriot, the Churchman, and the Stamp Collector. But his poetical creed he never consciously changed, though he often lapsed from it unconsciously. If Scott was to be a poet at all he was fated to be influenced by the New World, not in its emancipated ideas, but in its wistful return to the Old World of reivers, spearmen, claymores, goblin, ghost, and fairy. The Border ballads lulled his cradle and were the joy of his childhood and manhood."}]}
{"messages": [{"role": "assistant", "content": "The Border ballads lulled his cradle and were the joy of his childhood and manhood. All tradition murmured to him her charms of Border and Highland legend; every ruined abbey and castle had its tale for him; to Ettrick and Yarrow he needed not to say, like Lady John Scott, “Have you no message for me?” He never had a touch of the Augustan horror of mountain and torrent, never a touch of the Augustan contempt of “Barbarism.” Walpole’s _Castle of Otranto_ and Mrs. Radcliffe’s novels of terror went to the molding of his genius, as the novels of Miss Edgeworth (born 1767) suggested fiction about the lives and manners of his own people. In his return to the past he came, like Lamb, on the Elizabethan drama, and, unlike Lamb, on the unpublished documents of the Tudor age, the age of desperate resistance to England. But Scott would never have been exactly the poet that he was if he had not heard “Christabel” recited. “Christabel,” the entirely original utterance of a genius which, at first, was a child of the enlightenment of the eighteenth century."}]}
{"messages": [{"role": "assistant", "content": "“Christabel,” the entirely original utterance of a genius which, at first, was a child of the enlightenment of the eighteenth century. The early ideas of Coleridge were the ideas of Rousseau and of Bernardin de Saint Pierre, who was, like Coleridge, but more energetically, a seeker for an ideal land where pantisocracy might flourish and a clown might be the poet’s “brother.” \nIn poetry, in poetic form, Coleridge was the real and daring innovator, inspired by the eighteenth century reaction against convention, and played on like an æolian harp by every wind of his mystic spirit. His reaction was too violent even for Lamb; his originality too extreme even for Wordsworth. In him, of all our later poets, the “unconscious self” was the strongest and the most free, and of all our poets he had the hardest battle with the dull Augustan survival in such critics as Jeffrey. To them all the ripened fruit of the blossoming time of the late eighteenth century, the poetry of Scott and of Wordsworth, was but dimly intelligible, but Coleridge was the most unintelligible of all. From the Germany of the late eighteenth century came one of Scott’s springs of poetic action; from the _Lenore_ of Bürger (a popular ballad rewritten) and from the _Götz von Berlichingen_ of Goethe."}]}
{"messages": [{"role": "assistant", "content": "From the Germany of the late eighteenth century came one of Scott’s springs of poetic action; from the _Lenore_ of Bürger (a popular ballad rewritten) and from the _Götz von Berlichingen_ of Goethe. These were the days when Scott longed to possess a skull and cross-bones, and in a love-letter dilated on his choice of a sepulchre. But what came to Coleridge from Germany was the late eighteenth century’s reaction against the truly “common-sense” ideas of Hume, the philosophy of Kant, Schelling, and Fichte. In this field, too, he was unintelligible (and no wonder), but he was but adapting the ideas of 1770–1800, and the neo-Hegelians of Oxford are doing the same thing. A reaction against the materialism of common-sense was inevitable; Mesmer, Swedenborg, and Kant began what survives in the hands of the Master of Balliol and of Professor William James. In a more recent generation Byron prolonged the Wertherism of Werther, Byron being thus a grandson of Rousseau, while he borrowed his form, and borrowed it very ill, from what Scott borrowed of Coleridge."}]}
{"messages": [{"role": "assistant", "content": "In a more recent generation Byron prolonged the Wertherism of Werther, Byron being thus a grandson of Rousseau, while he borrowed his form, and borrowed it very ill, from what Scott borrowed of Coleridge. The genius of Byron is not contested by the sane, but except in satire it seldom found clear and adequate, because it sought hurried, heedless, and tumultuous, expression. Scott had a better ear and was not so reckless an _improvisatore_. Poems that can endure are not written like Byron’s, in the brief leisure of fashionable industry. We admire the native impetus of Byron, his gift of satire, his sensitiveness to elemental force in nature and in man, but we cannot understand the furore which was so much the child of his title, his beauty, his recklessness, and his studiously cultivated air of mystery. Mr."}]}
{"messages": [{"role": "assistant", "content": "Mr. Lenville, as reported by Mr. Folair, said that Nicholas Nickleby was “a regular stick of an actor, and it’s only the mystery about him that has caused him to go down with the people here, though Lenville says he don’t believe there’s anything at all in it.” A later age must partly adopt the same theory of Byron’s original and unparalleled success in Europe as well as in England. He was mysterious Manfred, he was Childe Harold, he was the Corsair; a hero of Mrs. Radcliffe’s, with an Oriental air and a gloomy secret and a heart burning with indignation against the unworthy species of men. What had Byron done?"}]}
{"messages": [{"role": "assistant", "content": "What had Byron done? Even Goethe was curious, believing wild anecdotes; now we really do not care what Byron did, recognizing in him, his genius, and his pose, not so much the “Satanic,” as the result of hysteria and madness in his race. Satanism, from of old, has been mainly hysteria. The element of personal _reclame_ in Byron has faded, and with it fades his reputation as an earth-shaking poet. Attempts to revive that fame in our day, attempts to bring us back to “the noble poet,” are respectable, being based on loyalty to the taste of our great-grandfathers and grandmothers in all civilized countries. But the efforts are futile."}]}
{"messages": [{"role": "assistant", "content": "But the efforts are futile. “Byron,” says Mr. Saintsbury, “seems to me a poet distinctly of the second class, and not even of the best kind of second, inasmuch as his greatness is chiefly derived from a sort of parody, a sort of imitation of the qualities of the first. His verse is to the greatest poetry what melodrama is to tragedy, what plaster is to marble, what pinchbeck is to gold.” Such, however unpopular they may be, are my own candid sentiments, for though from childhood I could and did read all our great poets with pleasure, it was not with the kind of pleasure which Byron in his satire and his declamation could occasionally give me. He is monotonous, he is rhetorical, his versification is often incredibly bad, and he is more obscure, mainly by dint of hurry, bad printing, and bad grammar, than Mr. Browning."}]}
{"messages": [{"role": "assistant", "content": "Browning. Thus Byron leaves us impressed as with a vast, even volcanic, yet dandified force, untrained and often misdirected. Either by nature, or in reaction, he professed sympathy with the Augustan school of Queen Anne’s reign, and sided with Pope in the long quarrel as to whether Pope is a poet. Even the modern opponents of Byron must recognize in him qualities which won the admiration and affection of Scott and Shelley. In Shelley we had a true child of the revolution, the _Aufklarung_, and the later eighteenth century. His boyhood trifled with chemical science (probably not then popular with the human boy); his adolescence was given to converting school-girls into “dear little atheists.” His social ideas, like those of some advanced moderns, aimed at the absolute destruction of the family; and the moral of _Laon and Cythna_ went far behind the morals of the most backward savages, who make incest a capital offence."}]}
{"messages": [{"role": "assistant", "content": "His boyhood trifled with chemical science (probably not then popular with the human boy); his adolescence was given to converting school-girls into “dear little atheists.” His social ideas, like those of some advanced moderns, aimed at the absolute destruction of the family; and the moral of _Laon and Cythna_ went far behind the morals of the most backward savages, who make incest a capital offence. Shelley, a boy all his life, was more boyishly devoted to destruction than even the newest writers on the relations of the sexes. In “making all things new” both he and they are, in fact, relapsing on a condition of society which, if it ever existed, is so old that it may be called “pre-human,” and is contrary to nature, as far as we can study human nature in the least developed of tribes. His ideas conducted Shelley to the tragedy and farce of his career: his desertion of one young wife, followed by her suicide, and his marriage with another, in entire opposition to his own opinions. In literature he began at school with a devout following of Mrs. Radcliffe; while, in _Queen Mab_ and _Alastor_, vigorous but vague and misty _Childe Harold_, wandering in No Man’s Land, he first displayed his originality in poetical form."}]}
{"messages": [{"role": "assistant", "content": "Radcliffe; while, in _Queen Mab_ and _Alastor_, vigorous but vague and misty _Childe Harold_, wandering in No Man’s Land, he first displayed his originality in poetical form. His personal character being noble and generous in the highest degree, his sympathy with the poor and the oppressed being a true passion, Shelley’s errors arose from the fixed idea that almost every human ordinance must, being old, be necessarily bad. He would recognize that there is, after all, something right in the sixth commandment, but did not draw the inference that a gleam of reason might also be found in most of the rest of the Decalogue. The state of society then, as always, provoked revolt, but the state of society was grievous, not because its moral laws were bad, but because its laws were not obeyed. Shelley had no turn for narrative, and, in such poems as _The Revolt of Islam_, it is the splendid meteoric genius, the unexcelled music that captivate. In lyrics he was probably the most original force since the Elizabethan age: his verse is a singing and soaring flame."}]}
{"messages": [{"role": "assistant", "content": "In lyrics he was probably the most original force since the Elizabethan age: his verse is a singing and soaring flame. In _Adonis_ his righteous indignation carries him forward like an angel with a sword of fire; and _The Witch of Atlas_ is a triumph in a new “fairy way of writing.” His is the Muse of clouds and stars, of sea and tempest, of all the aspects, and, in appearance, most capricious forces of the world, yet his is also the Muse of flowers and peaceful woods, of dejection and of delight. What the born rebel, Milton, might have been without the foundation and trammels of Puritanism, that Shelley was, though his wild and tender lyric note was even more exquisite than Milton’s. Neither was, in the full sense, human, for both were without humor, as may be seen in their humorous pieces. Keats, but three years younger than Shelley (1795), was more a true child of the nineteenth century. His social ideas, though of course liberal, were more in abeyance; he was more exclusively an artist; and his art was more controlled by the revived Elizabethanism of Leigh Hunt (1784)."}]}
{"messages": [{"role": "assistant", "content": "His social ideas, though of course liberal, were more in abeyance; he was more exclusively an artist; and his art was more controlled by the revived Elizabethanism of Leigh Hunt (1784). That singular man, who had so much taste, and so much of it bad; so intense a theory of social benevolence, and so keen a belief that it was more blessed to receive than to give, “owed little” (in the way of literature) “to any but the old masters, and many contemporaries owed not a little to him.” Few owed more, for good and bad, than Keats. Virgil he had found out for himself, and had translated when a schoolboy. Spenser, too, he found for himself, and Greece he discovered afresh in Lemprière’s _Dictionary_ and in Chapman’s _Homer_. But this superficial euphuism and elaborate verbal quaintness he partly derived at second hand from Leigh Hunt. That something in Leigh Hunt which suggested Harold Skimpole to Dickens, and his violent conception of _The Cockney School_ to Lockhart, was not hidden from Keats, and inspired him with some bitter words."}]}
{"messages": [{"role": "assistant", "content": "That something in Leigh Hunt which suggested Harold Skimpole to Dickens, and his violent conception of _The Cockney School_ to Lockhart, was not hidden from Keats, and inspired him with some bitter words. It was what he derived from Hunt that gave occasion to Keats’s assailants, who were more of political than of literary partisans. Lockhart, or Wilson, or both, with the _Quarterly_ reviewer, in attacking _Endymion_ were attacking, they thought, a member of an affected, effeminate, and radical coterie. Keats himself, maturing with the suddenness of genius, looked on _Endymion_ as thoroughly immature. But killed, or even discouraged, by his critics he was not, and on a page of a copy of _Lamia_ where his publishers spoke of his discouragment he wrote “This is a lie.” (The copy is in the possession of Canon Ainger.) Keats, like Burns, whom he so intensely admired and so unerringly judged as a man and a poet, was his own best critic. Despite his boyish lusciousness of taste, and the fever of letters written when dying, there was no manlier or more chivalrous soul in England than that of the poet of the odes to the nightingale and to autumn."}]}
{"messages": [{"role": "assistant", "content": "Despite his boyish lusciousness of taste, and the fever of letters written when dying, there was no manlier or more chivalrous soul in England than that of the poet of the odes to the nightingale and to autumn. Keats at his best attained sheer perfection of language, of emotion, and of thought. As he advised Shelley to be, he was not content with less than filling all the rifts with pure gold. “Untaught,” like the minstrel of Odysseus, he combined a Greek clarity and largeness of manner with that romance which Greece does not lack, but which he possessed in a degree more conspicuous, at least to readers who are not Greeks. Though he has not been and cannot be imitated, he has supplied to Tennyson and the best moderns a standard and an ideal. That the Shakespearian copiousness of humanity and humor and dramatic genius would ever have been his nothing indicates, but what writer of the nineteenth century, except Scott, has possessed a large share of these qualities?"}]}
{"messages": [{"role": "assistant", "content": "That the Shakespearian copiousness of humanity and humor and dramatic genius would ever have been his nothing indicates, but what writer of the nineteenth century, except Scott, has possessed a large share of these qualities? In poetry, not one, and it was in prose that Scott wore his fragment of the cloak of Shakespeare. For the century has not produced, in England or America, a great dramatic poet. It is to fiction, to Scott, Dickens, Thackeray, Stevenson, Meredith, Hawthorne, George Eliot, that we must look for the humor and humanity and passion which, earlier, found their vehicle in the drama. Ours is a reading rather than a seeing century, though this does not explain the reason which made the great novelists incapable of writing for the stage. Of the other poets of the early century, Campbell, Rogers, Moore, Landor, Hogg, and the ladies, Mrs."}]}
{"messages": [{"role": "assistant", "content": "Of the other poets of the early century, Campbell, Rogers, Moore, Landor, Hogg, and the ladies, Mrs. Hemans, and L. E. L., and Beddoes, space does not permit us to treat. Landor’s audience has not increased; Rogers has none; Campbell is best remembered for war songs which I fear are overrated; Hogg, despite some exquisite passages in _Kilmeny_, and some admirable songs, suffers from his countrymen’s exclusive devotion to Robbie Burns. When Scott turned to fiction (1814) the current of popular taste at once changed into that channel."}]}
{"messages": [{"role": "assistant", "content": "When Scott turned to fiction (1814) the current of popular taste at once changed into that channel. Byron had still his vogue; Keats, Shelley, and Coleridge then sang only to the few initiated; Wordsworth was past his prime; and with the general public nothing was really popular but fiction, and that fiction was Scott’s. Miss Austen is probably much more widely appreciated to-day than when she died, little noted by the world, in 1817. A criticism of Scott’s novels, which first made fiction supreme and far above poetry in the estimation of “the reading public,” cannot be attempted in this place. The best estimate of Scott, if far from most favorable, is his own, in the introduction to _The Fortunes of Nigel_. His faults of prolixity, haste, indifference to delicacy of style, and even to grammar; his “big bow-wow” vein (as he calls it); the stilted theatrical language of his Catherine Glovers and Helen Macgregors—all these defects, with his hasty denouéments (as of Shakespeare and Molière), are patent, are confessed, and probably deter many readers from making profit of his humor, his rich knowledge of and sympathy with all human nature, his infrequent but exquisite touches of passion, his tragedy and comedy."}]}
{"messages": [{"role": "assistant", "content": "His faults of prolixity, haste, indifference to delicacy of style, and even to grammar; his “big bow-wow” vein (as he calls it); the stilted theatrical language of his Catherine Glovers and Helen Macgregors—all these defects, with his hasty denouéments (as of Shakespeare and Molière), are patent, are confessed, and probably deter many readers from making profit of his humor, his rich knowledge of and sympathy with all human nature, his infrequent but exquisite touches of passion, his tragedy and comedy. None the less, Scott is the main stock of the fiction of the century. Men may now have more minute knowledge, though so wide a knowledge has none; may have more wit, if less humor; may eagerly hunt for all that Scott loathed and avoided in our animal nature; may, indeed must, practise a more careful style, but all the novelists are, willy-nilly, children of Scott and Miss Austen. Dickens, indeed, owed more to Smollett (one of Scott’s chief favorites), Thackeray owed more to Fielding, the “Kailyard School” owed more to Galt (1779—1839). But Scott is “the father of the rest,” above all, of Dumas; and Miss Austen is the mother. Lord Lytton and Mr."}]}
{"messages": [{"role": "assistant", "content": "Lord Lytton and Mr. Disraeli had, especially at first, a tinge of Byronism, later developing on their own lines: Mr. Disraeli’s political; Lord Lytton’s multifarious, including the line of modern mysticism, now often worked. Scott lived to be interested in Lytton, and might have seen (though probably he did not see them) the little-noted beginnings of Browning and Tennyson, about 1830. What he did see, and admire, was the performance of Cooper, with whom actual and living American fiction may perhaps be said to take its rise. In England, Cooper was regarded as the Scott of America; and it is to be regretted that Lockhart did not excise a splenetic personal reference to Cooper in Sir Walter’s _Journal_."}]}
{"messages": [{"role": "assistant", "content": "In England, Cooper was regarded as the Scott of America; and it is to be regretted that Lockhart did not excise a splenetic personal reference to Cooper in Sir Walter’s _Journal_. He was old, tired, and fatigued with the pressure of society in Paris when he wrote. Cooper had the genius to appropriate the unworked fields of American patriotic seafaring life, and of the manners of the Red Man; he is “Cooper of the wood and wave.” Eagerly were his works read by boys, when Thackeray was a boy, and when I was a boy. Never shall his readers forget the “Long Carabine,” to whom Thackeray was devoted, and Uncas, and Chingachgook. “Still we love the Delaware,     And still we hate the Mingos.” \nDoubtless Cooper’s Indians are not “realistically” treated, though there is infinitely more of truth in his dignified hunters and warriors than people conversant only with the Red Man of to-day are ready to believe. But Cooper, probably, does not live with the immortality of his first renowned successor, Hawthorne, who, for secure perfection of form, is to modern fiction what Keats is to modern poetry."}]}
{"messages": [{"role": "assistant", "content": "But Cooper, probably, does not live with the immortality of his first renowned successor, Hawthorne, who, for secure perfection of form, is to modern fiction what Keats is to modern poetry. Like Scott, Hawthorne is the unforced fruit of his ancestry and the society into which he was born—a Puritan, not a Cavalier artist, with a background of austere faith and of old superstition, differentiated from that of the Covenanters by the shadow of deep forests and of struggles with the Indians and the wild things of the woods. These had passed into mellow memories, as, for Scott, had passed the age of witches, fairies, reivers, and claymores. Entirely, in the _Scarlet Letter_, as by way of hereditary influence in the _House of Seven Gables_, Hawthorne reproduced what was old, making it poetically enduring. _His Mosses from an Old Manse_, and other brief tales set the fashion, except by Poe, long unfollowed, of the _conte_. Neither author has been excelled in his own portion of this field."}]}
{"messages": [{"role": "assistant", "content": "Neither author has been excelled in his own portion of this field. Hawthorne’s haunted consciences, Poe’s treasure tale, his detective stories, and his tales of terror remain unequalled, though so profusely imitated. This epoch, say from 1830 to 1855, was a kind of classical interspace in the literature of the century. France, preoccupied by war in the first thirty years of the age, now awoke to her own famous romantic era, with Hugo, Dumas, Musset, Gautier, George Sand, Sainte-Beuve, Mérimée—names of the highest. Germany, to the non-Teutonic world, is, in poetry, represented by Heine, and, in science, philosophy, philology, and history by a galaxy of innovators ingenious and industrious. America saw Hawthorne, Poe, Lowell, Holmes, Whittier, Ticknor, Prescott, Motley, Longfellow, Bryant, Emerson, in their prime; while England had Carlyle, Tennyson, Newman, Browning, the Brontës, Kingsley, Thackeray, Dickens, and Ruskin, all recognized and flourishing."}]}
{"messages": [{"role": "assistant", "content": "America saw Hawthorne, Poe, Lowell, Holmes, Whittier, Ticknor, Prescott, Motley, Longfellow, Bryant, Emerson, in their prime; while England had Carlyle, Tennyson, Newman, Browning, the Brontës, Kingsley, Thackeray, Dickens, and Ruskin, all recognized and flourishing. We look around and see, as Mr. Stevenson says in a letter, that “the suns have set,” while we are scarcely conscious of new dawns. Who can explain, by circumstances of social evolution and historical event, the rising and the setting of such constellations of genius? It is not enough to speak of the democratic demand, naturally indifferent to style, for never was style the object of such anxious research, except in other ages of euphuism. Encouragement is even overabundant; “masterpieces” are announced every week, and forgotten every year."}]}
{"messages": [{"role": "assistant", "content": "Encouragement is even overabundant; “masterpieces” are announced every week, and forgotten every year. It may be the prejudice of hoary eld, but I must confess that our new literature does not seem to me to show such promise of permanence as the literature of 1830–1860 gave, and, so far, has fulfilled. Has fulfilled in spite of our sneers at the “early Victorian,” which was not socialistic, or evolutionist and Darwin-ridden, and was “respectable,” and did avert its eyes from all that most people in real life don’t care to stare at. This “prudery” was no new thing. The Greeks, in except some late decadents and in the old comedy, have a “prudish” literature. The Latin classics are not in the taste of M."}]}
{"messages": [{"role": "assistant", "content": "The Latin classics are not in the taste of M. Zola. The age of Chaucer, the age of Elizabeth, were grossly frank, that of the Restoration was frankly lewd, but we have sought out many inventions over which Sedley and Rochester would not have cared to linger. Their grossness was gay; ours is morbidly squalid. Such things are absent from the work of Hawthorne and Holmes, Longfellow, Dickens, Thackeray, and the rest. Such things we now treat of, greatly daring, and somehow our elders appear apt to outlaugh and outlive us as humorists, novelists, and poets."}]}
{"messages": [{"role": "assistant", "content": "Such things we now treat of, greatly daring, and somehow our elders appear apt to outlaugh and outlive us as humorists, novelists, and poets. It is strange. Into the merits of that remarkable middle age of the century we cannot enter in much detail. Tennyson holds unimperilled the throne of the poet of the time. That his thought is not especially penetrating, whether he deals with the intricacies of human character, or with the problems of the universe, may be readily admitted. But I am unaware that any poet has yet “got the absolute into a corner,” or solved the problems of the universe."}]}
{"messages": [{"role": "assistant", "content": "But I am unaware that any poet has yet “got the absolute into a corner,” or solved the problems of the universe. Tennyson, more than people suppose, was, personally, a mystic, with his own mystic experiences; and his philosophy was influenced by them. He “followed the Gleam.” Neither in the _Idylls of the King_ nor in plays, was dramatic rendering of character his forte. His forte was charm, and music, and the interpretation of nature. In these he is the equal of the Mantuan, is the Virgil of the modern world, “golden branch among the shadows.” Moreover, he has infinite variety: from _Mariana_ to _Fatima_ and _Rizpah_; from the _Lotos-Eaters_, which “adds a new charm” after the _Faërie Queene_, to the _Northern Farmer_, from _Ulysses_ to _Crossing the Bar_. The early _Morte d’Arthur_ is of unsurpassed nobility and magic; the last poem, _Crossing the Bar_, is no less pre-eminent in these qualities."}]}
{"messages": [{"role": "assistant", "content": "The early _Morte d’Arthur_ is of unsurpassed nobility and magic; the last poem, _Crossing the Bar_, is no less pre-eminent in these qualities. Tennyson, in short, had genius; new, as all genius is new, and no occasional defects of taste or temper can impair the splendor and richness of his gift to the world, nor the immortality of his fame. His contemporary, Browning, had the misfortune to attract, by his faults, the people who wish to believe themselves clever, because they labor at appreciating passages which the poet had made obscure. Darkness is not depth, nor is obscurity a merit. From his letters it is plain that Mr. Browning had not the gift of lucid expression; from his poems it is manifest that he had not, in a high degree, the gift of verbal music and of charms."}]}
{"messages": [{"role": "assistant", "content": "Browning had not the gift of lucid expression; from his poems it is manifest that he had not, in a high degree, the gift of verbal music and of charms. His gift of the grotesque, very real and original, was also his snare. In _Christmas Eve_ and _Easter Day_, with _Men and Women_, we have the true essence of Browning at his best; we have his dramatic lyrics, with their amazing abundance of character and variety of measure. After the first fascinating volume _The Ring and the Book_ became monotonous. One song in _Paracelsus_, to myself, seems worth all the dissection of character in the blank verse. There are many who find a kind of spiritual help in such pieces as _Prospice_."}]}
{"messages": [{"role": "assistant", "content": "There are many who find a kind of spiritual help in such pieces as _Prospice_. There are thousands who find in _Men and Women_ a sort of intellectual enjoyment (or entertainment) which they can derive from no other poet who ever lived. An energy, life, and sympathy, breaking forth in fresh, unheard-of ways; vocal in strange, piercing, untried measures: these are the imperishable qualities of Browning. Look at his rendering of the Agamemnon: such is his version of life. The poetry of Æschylus is not there: “_carmina desunt_”; but there is a new, odd, unexpected rendering of the tragedy. So poignant and broken, sad, glad, grotesque, and pitiful, was Browning’s rendering of life."}]}
{"messages": [{"role": "assistant", "content": "So poignant and broken, sad, glad, grotesque, and pitiful, was Browning’s rendering of life. He was “ever a fighter”: no poet is more exempt from whining and despair. Destiny linked him with Mrs. Browning, whose genius, sincere and original, is apt to be obscured by palpable faults of manner, emotion, and even rhyme, on which it is superfluous to dwell. Her merits, and some of her defects, made Mrs. Browning the most popular of women poets in England, except, perhaps, Miss Ingelow."}]}
{"messages": [{"role": "assistant", "content": "Browning the most popular of women poets in England, except, perhaps, Miss Ingelow. Both, in the crowd of accomplished versifiers, appear as true poets, though both, no doubt, fail to reach the place of Miss Christina Rossetti, who never can be popular. The matter of popularity is full of puzzles and paradoxes. Tennyson was popular, yet great because he is popular. There was a moment when popularity without permanence might have been expected for Longfellow. The excellence of his moral intentions was then more obvious than the poetry."}]}
{"messages": [{"role": "assistant", "content": "The excellence of his moral intentions was then more obvious than the poetry. Such early pieces as _Excelsior_ and _The Psalm of Life_ yield odd results on analysis. But not much better can be said for the _Queen of the May_, and for parts of _The Miller’s Daughter_. In these is a marvellous dexterity in sinking. But sink, and remain sunk, was as little characteristic of Longfellow as of Tennyson. He was a true poet, in his lyrics, even in his translations, as well as in _Evangeline_, and that excellent experiment _Hiawatha_, where the measure of the Finnish popular poems is applied to the not dissimilar legends of another woodland race."}]}
{"messages": [{"role": "assistant", "content": "He was a true poet, in his lyrics, even in his translations, as well as in _Evangeline_, and that excellent experiment _Hiawatha_, where the measure of the Finnish popular poems is applied to the not dissimilar legends of another woodland race. But Longfellow lacked that undefinable quality of the rare, the strange, the hitherto unheard yet delightful note which now and again is heard in the verse of Edgar Poe. He was an Ishmaelite in literature, his hand against every man’s hand, and hence seems to be less admired where he was personally known than in France and England. It is not the famous _Raven_, but such pieces as _To Helen_, _the Sleeper_, and at most a dozen others which give Poe his high place in the judgment of his admirers. Not his ideas, but the beauty of his haunting lines, confers on him the laurel. Of Bryant, as a rule, and of Whittier almost always, the reverse is the truth."}]}
{"messages": [{"role": "assistant", "content": "Of Bryant, as a rule, and of Whittier almost always, the reverse is the truth. The acceptability of their ideas, the refined simplicity, not the natural magic, of their form, are their claims to renown. Except in a few places, as in such as his _Commemoration Ode_, Mr. Lowell is better remembered for the wit and vigor of his Biglow poems than for his serious verse, at least in England; while Emerson’s prose has precedence here over his poetry. The wisdom of the East and West, blended with his happy, courageous temper, made Emerson a corrective Carlyle, while Thoreau is the complement of Emerson. Concerning the great Victorian novelists, Thackeray and Dickens, so much is daily written that remark is superfluous."}]}
{"messages": [{"role": "assistant", "content": "Concerning the great Victorian novelists, Thackeray and Dickens, so much is daily written that remark is superfluous. A master of observation of all that had rarely been observed, a generous heart, an original and abundant humorist, the greatest source of mirth in our century, Dickens appears to wear less well than his rival. The unapproached merits of Thackeray’s style must preserve him in literature; his pathos is rare and unforced; his form of humor is as permanent as that of Fielding, and as successfully matched by his phrasing. Even his verse, mirthful or melancholy, does not fade, and has its own place on the borderland of poetry. George Eliot’s fame, too, must revive the success of her earlier and more humorous novels, before she became too fond of the Spencerian philosophy, and took herself too seriously, a natural result of adulation. Charlotte Brontë, in the same way, has been, as it were, rediscovered amid a chorus of fresh applauses, and with perhaps rather too curious investigations."}]}
{"messages": [{"role": "assistant", "content": "Charlotte Brontë, in the same way, has been, as it were, rediscovered amid a chorus of fresh applauses, and with perhaps rather too curious investigations. In America, after Hawthorne, Dr. Oliver Wendell Holmes and Mrs. Beecher Stowe were the novelists most generally admired in England, when Thackeray and Dickens were verging to their decline. It is, indeed, to be regretted that Dr. Holmes did not write more fiction when in his prime."}]}
{"messages": [{"role": "assistant", "content": "Holmes did not write more fiction when in his prime. His excellent and original _Elsie Venner_, and _Guardian Angel_, with their humorous pictures of real life and their thread of phantasy, half mystical, half scientific, border (as often in the _Poet_ and _Professor at the Breakfast Table_) on the ground of “psychical research.” Dr. Holmes was not merely, in verse and prose, an exquisite wit, but a man of rare knowledge, a man of science, and a sturdy defender of the purity of the language. Mrs. Beecher Stowe, on the other hand, took the world by storm with a vivid tract in the form of fiction; a book now not easy to criticise, but which can still move to laughter and tears. It is my “insular ignorance” which prevents me from appreciating other American fictions of that age, before the days of writers still happily living and working: Mark Twain, Bret Harte, W."}]}
{"messages": [{"role": "assistant", "content": "It is my “insular ignorance” which prevents me from appreciating other American fictions of that age, before the days of writers still happily living and working: Mark Twain, Bret Harte, W. D. Howells, Henry James, and scores of others, who, being here to speak for themselves, shall not be commented upon in this place. With Mr. Howells, as a critic, I have tried to break lances, while ready to admit one of his main contentions, that the art of Scott, Thackeray, Dickens, and others of our fathers would have profited much by being a finer art, by condensation, by omission, by avoidance of the superfluous. But that our modern fiction is a greater art, that romance and story-telling and adventure are obsolete, or ought to be obsolete, that I can never admit while human nature is human nature."}]}
{"messages": [{"role": "assistant", "content": "But that our modern fiction is a greater art, that romance and story-telling and adventure are obsolete, or ought to be obsolete, that I can never admit while human nature is human nature. Mankind will never be content, in fiction, with tales of the psychology of the ordinary person; ordinary as we are, we desire to be, like Homer’s Heracles, conversant with great adventures. Mr. Howells perhaps may think Aristotle a Greek snob when he maintains that tragedy must find its theme in the sorrows of the god-descended kings. Are not the griefs of the poor or of the middle classes as poignant? They are; but they do not involve such heights and depths of fortune, raising or wrecking whole states, as do the woes “of Thebes, or Atreus’s line.” The fall of Prince Charles from an hour even of shadowy royalty, from the leadership of an army, from the wondering admiration of Europe and the applause of Voltaire into the subject and dependent sot is an example of modern historical tragedy; in its elevation and its decline more apt to move “pity and terror” than the circumstance that a journalist has taken to drink."}]}
{"messages": [{"role": "assistant", "content": "They are; but they do not involve such heights and depths of fortune, raising or wrecking whole states, as do the woes “of Thebes, or Atreus’s line.” The fall of Prince Charles from an hour even of shadowy royalty, from the leadership of an army, from the wondering admiration of Europe and the applause of Voltaire into the subject and dependent sot is an example of modern historical tragedy; in its elevation and its decline more apt to move “pity and terror” than the circumstance that a journalist has taken to drink. As in the case of America, so in that of England, I cannot enter into the merits of living novelists in so wide a task as the brief review of a century. Mr. Meredith, as a veteran of the 60’s, has shown, perhaps, fully what is the nature of his achievement; he shines as a creator of character (the highest praise) and as a writer with a thoroughly original view of the world, as a poet and as a wit. That his manner is entirely fortunate, and not rather tinged with wilful eccentricities like those of Browning and Carlyle, can scarcely be disputed. An accomplished young novelist has admitted to me that his manner is “catching,” and that he has to struggle against half-conscious efforts at imitation."}]}
{"messages": [{"role": "assistant", "content": "An accomplished young novelist has admitted to me that his manner is “catching,” and that he has to struggle against half-conscious efforts at imitation. Others do not struggle; and most grow older before they are able to write like themselves, with their own voices. Even Mr. Stevenson was caught now and then, his own voice being original indeed, but yet full of memories of the seventeenth and eighteenth centuries, and even of the Cameronian writers. To my mind Mr. Stevenson was the greatest, or, at least, the most enjoyable, of our novelists since George Eliot, excelling in matter and form, though probably always prevented by thwarting circumstances from doing himself complete justice."}]}
{"messages": [{"role": "assistant", "content": "Stevenson was the greatest, or, at least, the most enjoyable, of our novelists since George Eliot, excelling in matter and form, though probably always prevented by thwarting circumstances from doing himself complete justice. He practically revived in England the novel historical, now so abundantly practised, and practised with spirit, by Mr. Stanley Weyman, Mr. Anthony Hope, Dr. Conan Doyle, Mr. A."}]}
{"messages": [{"role": "assistant", "content": "A. E. W. Mason, and a regiment of followers. The novel scientific, as in the hands of Mr. Wells, and the novel of adventure, “beyond the bounds of known romanticism,” as in Mr."}]}
{"messages": [{"role": "assistant", "content": "Wells, and the novel of adventure, “beyond the bounds of known romanticism,” as in Mr. Rider Haggard’s works, with the detective novel and the Oriental and imperialistic romances of Mr. Kipling, prove that man will not be satisfied with domestic realism alone. I never thought he would! Mr. Kipling’s astonishing powers of vision, his habit of ruthlessly cutting the superfluous, and his amazing command of technicalities, help to account for his world-wide fame."}]}
{"messages": [{"role": "assistant", "content": "Kipling’s astonishing powers of vision, his habit of ruthlessly cutting the superfluous, and his amazing command of technicalities, help to account for his world-wide fame. But the greatest of these is vision, not an acquired result of thought, but a gift of Heaven. The age has also produced a wealth of novels with a purpose. Would that the authors could be induced to state their purposes squarely, in undecorative treatises! But I confess that the treatises would not be read. The specialism of modern science has also invaded fiction, and some authors find a county or a parish wide enough for the work of a lifetime."}]}
{"messages": [{"role": "assistant", "content": "The specialism of modern science has also invaded fiction, and some authors find a county or a parish wide enough for the work of a lifetime. The district has its dialect, and who can reprove it when spoken by the creatures of Mr. Barrie and Mr. Crockett? This kind of fiction is the result of our desire to learn (through novels) about the lives of all sorts and conditions of men. _Enfin_, the whole scope of mortal existence is now the _farrage libelli_ of the novelists who range from prehistoric man to Bethnal Green; from Thrums to Central Africa."}]}
{"messages": [{"role": "assistant", "content": "_Enfin_, the whole scope of mortal existence is now the _farrage libelli_ of the novelists who range from prehistoric man to Bethnal Green; from Thrums to Central Africa. There is not the same eagerness to read history, which James II. regarded as “more instructive, and quite as amusing.” My heart is here with King James, and I confess to gaining more entertainment from Carlyle’s _Frederick the Great_ than from most novels. The earlier historians, from Scott to Carlyle, Macaulay and Froude, placed the human interest in the front rank. They conceived that history had to do with human beings of passions, caprices, moods, loves, and hates, dwelling in a world of interesting costumes, arms, architecture, ideas, and beliefs. Thus Carlyle, with much research, created his Cromwell or his Frederick, as Scott created his Queen Mary, his Louis XI., his James VI., or his Cromwell in _Woodstock_, who is not too remote from Carlyle’s."}]}
{"messages": [{"role": "assistant", "content": "Thus Carlyle, with much research, created his Cromwell or his Frederick, as Scott created his Queen Mary, his Louis XI., his James VI., or his Cromwell in _Woodstock_, who is not too remote from Carlyle’s. For these reasons Scott, Froude, Carlyle, and Macaulay really are “amusing” as well as instructive historians. When institutions and constitutions had to be described they were placed in separate compartments, as in the works of Hallam and Bishop Stubbs. Historians studied manuscripts, of course, but it was not held that only the unprinted was the valuable, that a new survey of known matter was absolutely valueless. In the end of the century we have history which is not “as interesting as a novel” (like that of Prescott, Motley, Froude, and Macaulay), but very far from gay. Novelty of research is, quite justly, insisted upon (though research is as old as Hemingburgh, and was much advanced by Gibbon, Carter, Rymer, Walpole, Tytler, and so on) till, by a natural error, every scrap won from a wilderness of charters is valued beyond its deserts."}]}
{"messages": [{"role": "assistant", "content": "Novelty of research is, quite justly, insisted upon (though research is as old as Hemingburgh, and was much advanced by Gibbon, Carter, Rymer, Walpole, Tytler, and so on) till, by a natural error, every scrap won from a wilderness of charters is valued beyond its deserts. The human interest is frowned upon; movements of forces, political and social, are treated in preference to personal character and adventure. Meticulous accuracy is insisted upon, till nervous students are actually afraid to publish. Even Mommsen, greatest of original students, is regarded as frivolous, even Curtius as “popular” by the modern school. It is natural to man to run into these excesses of reaction. Froude is not often accurate, Macaulay has prejudices, even Mr."}]}
{"messages": [{"role": "assistant", "content": "Froude is not often accurate, Macaulay has prejudices, even Mr. Freeman was not sound about Knights’ Fees and about a certain palisade. Now the public does not care about Knights’ Fees or about the Manor, much; nor even about the obscure early history of civic institutions. In fact, even references to authorities frighten away part of the public, whose timidity I do not applaud. The results of our frivolity and of the portentous gravity of some modern historians is that, since Mr. Green, scarcely any writer of history is read except for examinations."}]}
{"messages": [{"role": "assistant", "content": "Green, scarcely any writer of history is read except for examinations. As long as historians declare (often with perfect truth) that their own works are not literature, but something far more awful and solemn, namely science, history must be unpopular. But we are only waiting for a man of genius as accurate as the most meticulous, and as interesting as the agreeably irresponsible Froude. Of science I am not to treat, so I am dispensed from remarks on our scientific modern historians. It is certain that in collecting and printing and calendaring documents the age in all countries has shown praiseworthy industry, while Mr. Parkman in America, like our mid-century historians, was not too scientific to be readable."}]}
{"messages": [{"role": "assistant", "content": "Parkman in America, like our mid-century historians, was not too scientific to be readable. Of theology, except when recommended by the art of a Newman or a Jowett, nothing is here to be said; though I could cheerfully say a good deal, especially about Biblical criticism. But that is science, though scarcely the sort of science which has been defined as “organized common-sense.” The poetry of the late century in England boasts the names of Rossetti, William Morris, Matthew Arnold, and Mr. Swinburne. It is tinged, in the former with mediævalism derived from the Italians and Chaucer; while in Mr. Swinburne every conceivable literary influence, from the Greeks to Baudelaire, from the Elizabethans to Victor Hugo, makes itself abundantly conspicuous."}]}
{"messages": [{"role": "assistant", "content": "Swinburne every conceivable literary influence, from the Greeks to Baudelaire, from the Elizabethans to Victor Hugo, makes itself abundantly conspicuous. These poets, younger than Matthew Arnold, are not much influenced by Wordsworth, though by Shelley Mr. Swinburne was influenced. On the other hand, Mr. Arnold was a modern, academic, heterodox Wordsworth, and often a truly delightful poet. He stood much aloof from the contemporary literature of his day, and his letters prove that he was no fervent admirer even of Tennyson or Browning."}]}
{"messages": [{"role": "assistant", "content": "He stood much aloof from the contemporary literature of his day, and his letters prove that he was no fervent admirer even of Tennyson or Browning. His own poetry has been to many, as to myself, full of delightful passages, whether he wrote of the Oxford country-side, or of Wordsworth’s hills, of “the shorn and parcelled Oxus,” or of the moaning sea that Sophocles long ago heard as he heard it on Dover beach. He was our greatest modern elegiac poet; a master of the Dirge. Of the living, again, no criticism can be offered; we only note the names, and real if very various merits, of Mr. Robert Bridges, Mr. Watson, Mr."}]}
{"messages": [{"role": "assistant", "content": "Watson, Mr. Davidson, Mr. Dobson, Mr. Benson, Mr. Thompson, Mr. Henley, Mr."}]}
{"messages": [{"role": "assistant", "content": "Henley, Mr. Gosse, Mr. Stephen Philips, Mrs. Marriott Watson, Mrs. Maynell, Mr. Kipling, “a nest of singing birds.” It would be impertinent, and indeed perilous, to “draw invidious distinctions,” as the undergraduate said about the major and minor prophets: nor is it for this century to sift the poetic sheep from the goats, who, in an age that reads little poetry, are greatly guilty of much verse."}]}
{"messages": [{"role": "assistant", "content": "Kipling, “a nest of singing birds.” It would be impertinent, and indeed perilous, to “draw invidious distinctions,” as the undergraduate said about the major and minor prophets: nor is it for this century to sift the poetic sheep from the goats, who, in an age that reads little poetry, are greatly guilty of much verse. The unassuming and decried art of criticism remains. Essays are of no one age; there are similar excellences in every good essayist since Montaigne. We have no Hazlitt, Lamb, or Leigh Hunt, but we had Mr. Stephenson and Mr. Pater, so unlike in all but conscious interest in style, and reminiscence of the best models."}]}
{"messages": [{"role": "assistant", "content": "Pater, so unlike in all but conscious interest in style, and reminiscence of the best models. Indeed, essay writing is almost an unpractised art, as the public “has no use for it,” any more than for the letter H on the Sandwich boards. A fairly bad novelist can live; to an appallingly bad novelist the workhouse unfolds its awful valves. In literary criticism Mr. Arnold stood alone in his age, and Mr. Arnold’s literary income, it is known, surprised, when stated, the Commissioners of Income Tax: not by its affluence."}]}
{"messages": [{"role": "assistant", "content": "Arnold’s literary income, it is known, surprised, when stated, the Commissioners of Income Tax: not by its affluence. Of living critics it would be in the highest degree dangerous to say a word, though many words, both of praise and dispraise, might be said of a person of reckless character. That (with obvious exceptions) most critics are men intimately familiar with what is best, from Homer to Mr. Stephen Philips, few students would venture to aver. That we (for am I not the least of all critics, and not worthy to be called a critic?) are entirely devoid of ignorance, personal bias, likes, dislikes, prejudices, pet aversions, indolence, we are not so blindly conceited as to maintain. We have been taught by many centuries of creative geniuses, from Theocritus to the latest protesting popular novelists, to know our proper place, and we take refuge in “confession and avoidance.” The new century will not know our names when we pass where Dennis and where Cibber are, unless Mr."}]}
{"messages": [{"role": "assistant", "content": "We have been taught by many centuries of creative geniuses, from Theocritus to the latest protesting popular novelists, to know our proper place, and we take refuge in “confession and avoidance.” The new century will not know our names when we pass where Dennis and where Cibber are, unless Mr. Robert Buchanan writes a new _Dunciad_. The century, even if we are in full decadence (of which we are not the best judges), has been glorious in literature, and holds its own well with any in modern history. English itself has passed from the occasionally stilted Augustan survival, through the novelties of Macaulay, De Quincey, and Carlyle, and the early decorated of Mr. Ruskin, into slipshod slang in one extreme, and euphuism in the other. But the main stream keeps its course, and English may be written with perfect purity, and with new fluency and variety, by the men for whom the task is reserved by fate."}]}
{"messages": [{"role": "assistant", "content": "But the main stream keeps its course, and English may be written with perfect purity, and with new fluency and variety, by the men for whom the task is reserved by fate. But what does the century bequeath by way of intellectual motive? Little but the more or less transformed forces of the eighteenth century. There is science, but science, happily, is beginning to be aware that she is not really omniscient. Conceivably her foot is on the border of a new region, often surmised, never explored, full of light on the problems of spirit and matter. Hence, indeed, might come a new force in letters."}]}
{"messages": [{"role": "assistant", "content": "Hence, indeed, might come a new force in letters. Again, the social ideas of 1750–1800 may take practical shapes of incalculable momentousness, but these would not for long be favorable to literature. Or, less probably, the return on the past may assume practical shape, though this element of the later eighteenth century may seem, as far as letters go, to be exhausted. In brief, as I began by saying, the division of literary periods by measures of time is a cross-division. This peculiarity the last hundred years possess: that literature now blossoms on a far wider field. English-speaking America had, indeed, a literature long before the War of Independence; but it was not a literature for every reader of to-day."}]}
{"messages": [{"role": "assistant", "content": "English-speaking America had, indeed, a literature long before the War of Independence; but it was not a literature for every reader of to-day. Now, and for long, the States have taken their own part in history, fiction, poetry, and all other branches of letters. Germany came back into world literature again just at the ending of the eighteenth century, after unregarded ages of neglect. Russia and the Scandinavian North awoke about the same time, and daily widen their influence, as does Belgium in the sunshine of Maeterlinck. France, of course, has in all time been in the foremost rank; while to balance America, Russia, and the North, Italy and Spain have scarcely held the place which through so many centuries was their own. Such changes in national literatures resemble the political waxings and wanings of national fortunes."}]}
{"messages": [{"role": "assistant", "content": "Such changes in national literatures resemble the political waxings and wanings of national fortunes. The English-speaking peoples may have their eclipse; perhaps it is heralded by a modern comparative deficiency in humor which, if England and America cease to laugh, will die out of a profoundly solemn world. In the foregoing remarks little has been said about the literature of the century except among English-speaking peoples. Not being a Mezzofanti, I am not personally acquainted with the literature of all languages, and it is a vain thing to speak of books at second hand. It was not the nineteenth but the eighteenth century that saw Germany re-enter the field of pure literature, as distinguished from that of scholarship and science. Since the end of the Middle Ages, with their poets, German writers had mainly been devoted to theology and classical criticism."}]}
{"messages": [{"role": "assistant", "content": "Since the end of the Middle Ages, with their poets, German writers had mainly been devoted to theology and classical criticism. Latin was the language of the learned. Many ascertainable causes, in the middle and end of the eighteenth century, and doubtless many causes which cannot be ascertained, awoke again the Teutonic genius. The victories of Frederick the Great gave Germans patriotism and confidence in their own tongue. The philosophic and social works which preluded to the French Revolution stirred the German mind and required popular expression. Thus Kant wrote in his own native speech in reaction against the sceptical philosophy of David Hume, and Kant became the father of the long array of German metaphysicians from Hegel and Fichte to Schopenhauer and Hartmann."}]}
{"messages": [{"role": "assistant", "content": "Thus Kant wrote in his own native speech in reaction against the sceptical philosophy of David Hume, and Kant became the father of the long array of German metaphysicians from Hegel and Fichte to Schopenhauer and Hartmann. Their philosophy “cannot be briefly stated, especially in French,” as one of them said, but its general effect has been rather to counteract materialism by making it pretty plain that human nature is not so simple and easily to be explained as the Scottish philosophers were apt to suppose. In England, Coleridge gave an Anglican heart to the new German philosophy, which also influenced Hamilton, and still affects the philosophical teaching of Oxford. “It is nonsense, but is it _the right sort_ of nonsense?” asked the late Professor Sidgwick (a Cambridge man) when struggling with the examination papers of a Hegelian undergraduate. More important as literature were the double influences of return on the mediæval past and of inspiration by the new political and social ideas which gave the impulse to the genius of Goethe, Schiller, Bürger, and others. Goethe began as the child of Rousseau, but as a child who had read Kant, and drunk deep of the romance of the Middle Ages."}]}
{"messages": [{"role": "assistant", "content": "Goethe began as the child of Rousseau, but as a child who had read Kant, and drunk deep of the romance of the Middle Ages. Doubtless his is the greatest name of modern Germany, both as a student of life, of nature, of history, and of thought. He was the spiritual parent of Scott, with his _Götz von Berlichingen_, and, with Richter, of Carlyle. Through himself and his English or Scottish disciples, Goethe has been the most fertile source of change in the literature of the nineteenth century. In extreme old age, curious to say, he gave the first impulse to the study of early religion as displayed in the obscure rites and beliefs of the Australian natives: a theme remote enough from his effect on the poetry of Matthew Arnold. Probably the two parts of his _Faust_ and his _Roman Lyrics_ are the most popular, and, as literature, the most permanent parts of his work, with _Werther_, _Wilhelm Meister_, and _Elective Affinities_, in prose."}]}
{"messages": [{"role": "assistant", "content": "Probably the two parts of his _Faust_ and his _Roman Lyrics_ are the most popular, and, as literature, the most permanent parts of his work, with _Werther_, _Wilhelm Meister_, and _Elective Affinities_, in prose. Schiller, beginning with the boyish romanticism of _The Robbers_, became a kind of classic in his later dramas. Lessing and Winckelmann were the most sound and fertile influences in criticism. _The Laocoon_ remains indispensable. The patriotic lyrists resurrected the national spirit of the Teutonic race, and Heine, Hebrew by race and half French in character, combined the characteristics of Lucian, Burns, and Voltaire. Wolf, writing in Latin (and I believe that his work on Homer has never attained a third edition, and has never been translated into English), became the parent, for good or evil, of what is called the Higher Criticism, Lachmann introducing the painfully conjectural tendencies of that intellectual exercise."}]}
{"messages": [{"role": "assistant", "content": "Wolf, writing in Latin (and I believe that his work on Homer has never attained a third edition, and has never been translated into English), became the parent, for good or evil, of what is called the Higher Criticism, Lachmann introducing the painfully conjectural tendencies of that intellectual exercise. Its application to scriptural texts is notorious, but not precisely as part of literature. Like other European countries, the Germany of the close of the century is not remarkable for resplendent genius in poetry or fiction, though novels abound. The scientific, historical, and scholarly literature is of vast profusion. In thoroughness and tireless patience, Germany is the teacher of the world, while in curious contrast to her practical genius is the love of some of her scholars for baseless conjecture. The “insularity” with which the English are charged is a matter of reproach by French scholars against Germany."}]}
{"messages": [{"role": "assistant", "content": "The “insularity” with which the English are charged is a matter of reproach by French scholars against Germany. Some sets of ideas, long familiar in America, England, and the Latin nations, are only now beginning to reach German classical scholars. To write an account of the changes in French literature during the century is impossible within moderate space. The revolutionary and Napoleonic wars were unfavorable to the literary art, and the head of so great a poet as André Chénier fell under the guillotine. Till about 1825–1830 the Restoration was accompanied by literature in the old classic style of Boileau and of the Augustan age, only enlivened by the romantic if somewhat affected style of that great rhetorician, Châteaubriand. The year 1830 is the sacred year of French romanticism, drawing its ideals partly from the German romantic movement, partly from Scott and Shakespeare, read, of course, only in translations."}]}
{"messages": [{"role": "assistant", "content": "The year 1830 is the sacred year of French romanticism, drawing its ideals partly from the German romantic movement, partly from Scott and Shakespeare, read, of course, only in translations. Everything was now to be mediæval, Spanish, and passionate: the drama was to be emancipated from Aristotle, also read in translations. As far as classicism went the young adventurers had no more Greek than Shakespeare or Scott. But they had the colossal and Titanic genius of Hugo, exquisitely sweet, rapid, strange, and versatile in lyric: potent, if inflated, in the drama and the novel. They had the charming humor and exquisite taste of Théophile Gautier; the feverish passion and mastery in verse of Alfred de Musset; the delicate, dreamy, and wandering spirit of Gérard de Nerval; and the manly, courageous, humorous, and unwearied vigor, in drama and in fiction, of Alexandre Dumas. This was, indeed, an extraordinary generation, by far the greatest since that of Corneille, Racine, and Molière."}]}
{"messages": [{"role": "assistant", "content": "This was, indeed, an extraordinary generation, by far the greatest since that of Corneille, Racine, and Molière. Many others might be named: the reserved force and incisive irony of Mérimée; the learned and genial criticism of Sainte-Beuve; the inexhaustible talent of George Sand, and the mighty Balzac, the maker and founder of the modern work of introspection. Probably, of all these writers, Dumas and Balzac have exercised most influence on later fiction in England and America. Flaubert continued, with painful elaboration, the traditions of Balzac; from Flaubert, and round him, grew up Daudet and M. Zola, and the Goncourts. Poetry, after Lamartine, dwindled into the prettinesses of the Parnasse and the eccentricities, too obviously intentional, of Baudelaire, Verlaine, and the Symbolistes."}]}
{"messages": [{"role": "assistant", "content": "Poetry, after Lamartine, dwindled into the prettinesses of the Parnasse and the eccentricities, too obviously intentional, of Baudelaire, Verlaine, and the Symbolistes. Literary art, at the end of the century, became too self-conscious, too fond of argument about ideals and methods, the tattle of the studio. Great men have not thus dissipated their energy; they have done what they could do; they have not talked about how they did it. What English literature was borrowed from France, at this time, is more in the nature of words than work. Criticism has been a _chimaera bombinans in vacuo_, chattering about realism, naturalism, symbolism, the use of documents, and so forth. The defects, rather than the merits, of France have been imitated; a squalid pessimism is easily affected."}]}
{"messages": [{"role": "assistant", "content": "The defects, rather than the merits, of France have been imitated; a squalid pessimism is easily affected. The closing century has seen Russia awake, as the close of the eighteenth century beheld the literary revival of Germany. Russian poetry has only reached the learned among us: the novels of Turguenieff, Dustoiefsky, and Tolstoï are read in translation, with curiosity, antipathy, enthusiasm, and an absence of that emotion. It is very long since Terentianus Maurus remarked that the fortunes of a book depended on the taste of the reader. Often he is favorably impressed, not by the actual merit of the story as a story or as a work of literary art, but by its appeal to his private sentiments, as of socialism, pessimism, toryism, or whatever they may be. Possibly the vehement admirers of some Russian writers have been thus misguided."}]}
{"messages": [{"role": "assistant", "content": "Possibly the vehement admirers of some Russian writers have been thus misguided. In any case, no qualified critic thinks that his opinion of works which he cannot read in the original language is of any value. For this reason I need not offend or please the reader by offering any uninstructed sentiments about the great Scandinavian dramatist, Dr. Ibsen; or concerning the work of Signor d’Annunzio, or the plays of M. Maeterlinck. To pronounce each of these gentlemen a Shakespeare or Æschylus is not unusual in cultivated circles; it remains for the new century to ratify or quash the verdict."}]}
{"messages": [{"role": "assistant", "content": "To pronounce each of these gentlemen a Shakespeare or Æschylus is not unusual in cultivated circles; it remains for the new century to ratify or quash the verdict. In the mean time, have the approving critics taken the precaution of reading Æschylus and Shakespeare? ANDREW LANG. ENGINEERING \n\nThe material prosperity of the last century is due to the co-operation of three classes of men: the man of science, who lives only for truth and the discovery of nature’s laws; the inventor, eager to apply these discoveries to money-making machines and processes, and the engineer, trained in mathematical investigation and in knowledge of the physical conditions which govern his profession, which is the mechanical application of the laws of nature. Engineering is sometimes divided into civil, military, and naval engineering. The term civil engineering, which will be here described, is often used by writers as covering structural engineering only, but it has a much wider meaning."}]}
{"messages": [{"role": "assistant", "content": "The term civil engineering, which will be here described, is often used by writers as covering structural engineering only, but it has a much wider meaning. The logical classification is: statical engineering, including that of all fixed bodies, and dynamical, covering the movement of all bodies by the development and application of power. Statical engineering can be again subdivided into structural engineering, or that of railways, highways, bridges, foundations, tunnels, buildings, etc.; also, into hydraulic engineering, which governs the application of water to canals, river improvements, harbors, the supply of water to towns and for irrigation, disposal of sewage, etc. Dynamical engineering can be divided into mechanical engineering, which covers the construction of all prime motors, the transmission of power, and the use of machines and machine tools. Closely allied is electrical engineering, the art of the transformation and transmission of energy for traction, lighting, telegraphy, telephoning, operating machinery, and many other uses, such as its electrolytic application to ores and metals. Then we have the combined application of statical, mechanical, and electrical engineering to what is now called industrial engineering, or the production of articles useful to man."}]}
{"messages": [{"role": "assistant", "content": "Then we have the combined application of statical, mechanical, and electrical engineering to what is now called industrial engineering, or the production of articles useful to man. This may be divided into agricultural, mining, metallurgical, and chemical engineering. Surely this is a vast field, and can only be hastily described in the sketch which we are about to give. STRUCTURAL ENGINEERING \nThis is the oldest of all. We have not been able to surpass the works of the past in grandeur or durability. The pyramids of Egypt still stand, and will stand for thousands of years."}]}
{"messages": [{"role": "assistant", "content": "The pyramids of Egypt still stand, and will stand for thousands of years. Roman bridges, aqueducts, and sewers still perform their duties. Joseph’s canal still irrigates Lower Egypt. The great wall of China, running for fifteen hundred miles over mountains and plains, contains one hundred and fifty millions of cubic yards of materials and is the greatest of artificial works. No modern building compares in grandeur with St. Peter’s, and the mediæval cathedrals shame our puny imitations."}]}
{"messages": [{"role": "assistant", "content": "Peter’s, and the mediæval cathedrals shame our puny imitations. These mighty works were built to show the piety of the Church or to gratify the pride of kings. Time and money were of no account. All this has now been changed. Capital controls, and the question of time, money, and usefulness rules everything. Hence come scientific design and labor-saving machinery."}]}
{"messages": [{"role": "assistant", "content": "Hence come scientific design and labor-saving machinery. The engineer of our modern works first calculates the stresses on all their parts, and proportions them accordingly, so that there is no waste of material. Hand labor has given place to steam machinery. All parts are interchangeable, so that they can be made and fitted together in the least possible time, as is seen every day in the construction of a steel-framed office building. Our workmen receive much higher wages than in the past, while time and cost have been diminished. RAILWAYS \nThe greatest engineering work of the nineteenth century was the development of the railway system which has changed the face of the world."}]}
{"messages": [{"role": "assistant", "content": "RAILWAYS \nThe greatest engineering work of the nineteenth century was the development of the railway system which has changed the face of the world. Beginning in 1829 with the locomotive of George Stephenson, it has extended with such strides that, after seventy years, there are 466,000 miles of railways in the world, of which 190,000 miles are in the United States. Their cost is estimated at forty thousand millions of dollars, of which ten thousand millions belong to the United States. The rapidity with which railways are built in the United States and Canada contrasts strongly with what has been done in other countries. Much has been written of the energy of Russia in building 3000 miles of Siberian railway in five or six years. In the United States an average of 6147 miles was completed every year during ten successive years, and in 1887 there were built 12,982 miles."}]}
{"messages": [{"role": "assistant", "content": "In the United States an average of 6147 miles was completed every year during ten successive years, and in 1887 there were built 12,982 miles. The physical difficulties overcome in Siberia are no greater than have been overcome here. This rapid construction is due to several causes, the most potent of which has been the need of extending railways over great distances with little money. Hence they were built economically, and at first in not as solid a manner as those of Europe. Steeper gradients, sharper curves, and lighter rails were used. This rendered necessary a different kind of rolling-stock suitable to such construction."}]}
{"messages": [{"role": "assistant", "content": "This rendered necessary a different kind of rolling-stock suitable to such construction. The swivelling-truck and equalizing-beam enabled our engines to run safely on tracks where the rigid European engines would soon have been in the ditch. Our cars were made longer, and by the use of longitudinal framing much stronger. A great economy came from the use of annealed cast-iron wheels, with hardened tires, all in one piece, instead of being built up of spokes, hubs, and tires in separate parts. These wheels now seldom break, and cost much less than European wheels. As there are some eleven million car-wheels in use in the United States the resulting economy is great."}]}
{"messages": [{"role": "assistant", "content": "As there are some eleven million car-wheels in use in the United States the resulting economy is great. It was soon seen that longer cars would carry a greater proportion of paying load, and the more cars that one engine could draw in a train, the less would be the cost. It was not until the invention by Bessemer in 1864 of a steel of quality and cost that made it available for rails that much heavier cars and locomotives could be used. Then came a rapid increase. As soon as Bessemer rails were made in this country, the cost fell from $175 per ton to $50, and now to $26. Before that time a wooden car weighed sixteen tons, and could carry a paying load of fifteen tons."}]}
{"messages": [{"role": "assistant", "content": "Before that time a wooden car weighed sixteen tons, and could carry a paying load of fifteen tons. The thirty-ton engines of those days could not draw on a level over thirty cars weighing 900 tons. The pressed steel car of to-day weighs no more than the wooden car, but carries a paying load of fifty tons. The heaviest engines have now drawn on a level fifty steel cars, weighing 3750 tons. In the one case the paying load of an engine was 450 tons; now it is 2500 tons. Steep grades soon developed a better brake system, and these heavier trains have led to the invention of the automatic brake worked from the engine, and also automatic couplers, saving time and many lives."}]}
{"messages": [{"role": "assistant", "content": "Steep grades soon developed a better brake system, and these heavier trains have led to the invention of the automatic brake worked from the engine, and also automatic couplers, saving time and many lives. The capacity of our railways has been greatly increased by the use of electric block-signals. The perfecting of both the railway and its rolling-stock has led to remarkable results. We have no accurate statistics of the early operation of American railways. In 1867 Poor’s Manual estimated their total freight tonnage at 75,000,000 and the total freight receipts at $400,000,000. This was an average rate per ton of $5.33."}]}
{"messages": [{"role": "assistant", "content": "This was an average rate per ton of $5.33. In 1899 Poor gives the total freight tonnage at 975,789,941 tons, and the freight receipts at $922,436,314, or an average rate per ton of ninety-five cents. Had the rates of 1867 prevailed, the additional yearly cost to the public would have been $4,275,000,000, or sufficient to replace the whole railway system in two and a half years. This is an illustration only, but a very striking one. Everybody knows that such high rates of freight as those of 1867 would have checked traffic. This much can surely be said: the reduction in cost of operating our railways, and the consequent fall in freight rates, have been potent factors in enabling the United States to send abroad last year $1,456,000,000 worth of exports and flood the world with our food and manufactured products."}]}
{"messages": [{"role": "assistant", "content": "This much can surely be said: the reduction in cost of operating our railways, and the consequent fall in freight rates, have been potent factors in enabling the United States to send abroad last year $1,456,000,000 worth of exports and flood the world with our food and manufactured products. BRIDGE BUILDING \nIn early days the building of a bridge was a matter of great ceremony, and it was consecrated to protect it from evil spirits. Its construction was controlled by priests, as the title of the Pope of Rome, “Pontifex Maximus,” indicates. Railways changed all this. Instead of the picturesque stone bridge, whose long line of low arches harmonized with the landscape, there came the straight girder or high truss, ugly indeed, but quickly built, and costing much less. Bridge construction has made greater progress in the United States than abroad."}]}
{"messages": [{"role": "assistant", "content": "Bridge construction has made greater progress in the United States than abroad. The heavy trains that we have described called for stronger bridges. The large American rolling-stock is not used in England, and but little on the continent of Europe, as the width of tunnels and other obstacles will not allow of it. It is said that there is an average of one bridge for every three miles of railway in the United States, making 63,000 bridges, most of which have been replaced by new and stronger ones during the last twenty years. This demand has brought into existence many bridge-building companies, some of whom make the whole bridge, from the ore to the finished product. Before the advent of railways, highway bridges in America were made of wood, and called trusses."}]}
{"messages": [{"role": "assistant", "content": "Before the advent of railways, highway bridges in America were made of wood, and called trusses. Few of them existed before railways. The large rivers and estuaries were crossed in horse-boats, a trip more dangerous than an Atlantic voyage now is. A few smaller rivers had wooden truss bridges. Although originally invented by Leonardo da Vinci, in the sixteenth century, they were reinvented by American carpenters. Some of Burr’s bridges are still standing after more than one hundred years’ use."}]}
{"messages": [{"role": "assistant", "content": "Some of Burr’s bridges are still standing after more than one hundred years’ use. This shows what wood can do when not overstrained and protected from weather and fire. The coming of railways required a stronger type of bridge to carry concentrated loads, and the Howe truss, with vertical iron rods, was invented, capable of 150-foot spans. About 1868 iron bridges began to take the place of wooden bridges. Die-forged eyebars and pin connections allowed of longer panels and longer spans. One of the first long-span bridges was a single-track railway bridge of 400-foot span over the Ohio at Cincinnati, which was considered to be a great achievement in 1870."}]}
{"messages": [{"role": "assistant", "content": "One of the first long-span bridges was a single-track railway bridge of 400-foot span over the Ohio at Cincinnati, which was considered to be a great achievement in 1870. The Kinzua viaduct, 310 feet high and over half a mile long, belongs to this era. It is the type of the numerous high viaducts now so common. About 1885 a new material was given to engineers, having greater strength and tenacity than iron, and commercially available from its low cost. This is basic steel. After many experiments, the proper proportions of carbon, phosphorus, sulphur, and manganese were ascertained, and uniformity resulted."}]}
{"messages": [{"role": "assistant", "content": "After many experiments, the proper proportions of carbon, phosphorus, sulphur, and manganese were ascertained, and uniformity resulted. The open-hearth process is now generally used. This new chemical metal, for such it is, is fifty per cent. stronger than iron, and can be tied in a knot when cold. The effect of improved devices and the use of steel is shown by the weights of the 400-foot Ohio River iron bridge, built in 1870, and a bridge at the same place, built in 1886. The bridge of 1870 was of iron, had panels twelve feet long, and its height was forty-five feet, and span 400 feet."}]}
{"messages": [{"role": "assistant", "content": "The bridge of 1870 was of iron, had panels twelve feet long, and its height was forty-five feet, and span 400 feet. The bridge of 1886 was of steel, had panels thirty feet long, and its height was eighty feet. Its span was 550 feet. The weights of the two were nearly alike. The cantilever design, which is a revival of a very ancient type, came into use. The great Forth Bridge, in Scotland, 1600-foot span, is of this style, as are the 500-foot spans at Poughkeepsie, and now a new one is being designed to cross the St."}]}
{"messages": [{"role": "assistant", "content": "The great Forth Bridge, in Scotland, 1600-foot span, is of this style, as are the 500-foot spans at Poughkeepsie, and now a new one is being designed to cross the St. Lawrence near Quebec, of 1800-foot span. This is probably near the economic limit of cantilever construction, but the suspension bridge can be extended much farther, as it carries no dead weight of compression members. The Niagara Suspension Bridge, of 810-foot span, built by Roebling, in 1852, and the Brooklyn Bridge, of 1600 feet, built by Roebling and his son, twenty years after, marked a wonderful advance in bridge design. Thirty years later, when a new bridge of 1600 feet was wanted to cross another part of the East River at New York, the same lines of construction were followed, and they will be followed in the 2700-foot span, designed to cross the North River some time in the present century. The only radical advance is the use of a better steel than could be had in earlier days."}]}
{"messages": [{"role": "assistant", "content": "The only radical advance is the use of a better steel than could be had in earlier days. Steel-arched bridges are now scientifically designed. Such are the new Niagara Bridge, of 840-foot span, and the Alexandra Bridge at Paris. It is curious to see how little is said about these beautiful bridges, which the public takes as a matter of course. If they had been built fifty years ago, their engineers would have received the same praise as Robert Stephenson or Roebling, and justly so, as they would have been men of exceptional genius. When these bridges were built, in 1898, the path had been made so clear by mathematical investigation and the command of a better steel, that the task seemed easy."}]}
{"messages": [{"role": "assistant", "content": "When these bridges were built, in 1898, the path had been made so clear by mathematical investigation and the command of a better steel, that the task seemed easy. That which marks more clearly than anything else the great advance in American bridge building, during the last forty years, is the reconstruction of the famous Victoria Bridge, over the St. Lawrence, above Montreal. This bridge was designed by Robert Stephenson, and the stone piers are a monument to his engineering skill. For forty winters they have resisted the great fields of ice borne by a rapid current. Their dimensions were so liberal that the new bridge was put upon them, although four times as wide as the old one."}]}
{"messages": [{"role": "assistant", "content": "Their dimensions were so liberal that the new bridge was put upon them, although four times as wide as the old one."}]}