Split (1)

train · 367k rows

text stringlengths 9 2.4k
However, Avicenna posited the brain as the place where reason interacts with sensation. Sensation prepares the soul to receive rational concepts from the universal Agent Intellect. The first knowledge of the flying person would be "I am," affirming his or her essence. That essence could not be the body, obviously, as the flying person has no sensation. Thus, the knowledge that "I am" is the core of a human being: the soul exists and is self-aware. Avicenna thus concluded that the idea of the self is not logically dependent on any physical thing, and that the soul should not be seen in relative terms, but as a primary given, a substance. The body is unnecessary; in relation to it, the soul is its perfection. In itself, the soul is an immaterial substance. Principal works. "The Canon of Medicine". Avicenna authored a five-volume medical encyclopedia, "The Canon of Medicine" (). It was used as the standard medical textbook in the Islamic world and Europe up to the 18th century. The "Canon" still plays an important role in Unani medicine.
"Liber Primus Naturalium". Avicenna considered whether events like rare diseases or disorders have natural causes. He used the example of polydactyly to explain his perception that causal reasons exist for all medical events. This view of medical phenomena anticipated developments in the Enlightenment by seven centuries. "The Book of Healing". Earth sciences. Avicenna wrote on Earth sciences such as geology in "The Book of Healing". While discussing the formation of mountains, he explained: Philosophy of science. In the "Al-Burhan" ("On Demonstration") section of "The Book of Healing", Avicenna discussed the philosophy of science and described an early scientific method of inquiry. He discussed Aristotle's "Posterior Analytics" and significantly diverged from it on several points. Avicenna discussed the issue of a proper methodology for scientific inquiry and the question of "How does one acquire the first principles of a science?" He asked how a scientist would arrive at "the initial axioms or hypotheses of a deductive science without inferring them from some more basic premises?" He explained that the ideal situation is when one grasps that a "relation holds between the terms, which would allow for absolute, universal certainty". Avicenna then added two further methods for arriving at the first principles: the ancient Aristotelian method of induction ("istiqra"), and the method of examination and experimentation ("tajriba"). Avicenna criticized Aristotelian induction, arguing that "it does not lead to the absolute, universal, and certain premises that it purports to provide." In its place, he developed a "method of experimentation as a means for scientific inquiry."
Logic. An early formal system of temporal logic was studied by Avicenna. Although he did not develop a real theory of temporal propositions, he did study the relationship between "temporalis" and the implication. Avicenna's work was further developed by Najm al-Dīn al-Qazwīnī al-Kātibī and became the dominant system of Islamic logic until modern times. Avicennian logic also influenced several early European logicians such as Albertus Magnus and William of Ockham. Avicenna endorsed the law of non-contradiction proposed by Aristotle, that a fact could not be both true and false at the same time and in the same sense of the terminology used. He stated, "Anyone who denies the law of non-contradiction should be beaten and burned until he admits that to be beaten is not the same as not to be beaten, and to be burned is not the same as not to be burned." Physics. In mechanics, Avicenna, in "The Book of Healing", developed a theory of motion, in which he made a distinction between the inclination (tendency to motion) and force of a projectile, and concluded that motion was a result of an inclination ("mayl") transferred to the projectile by the thrower, and that projectile motion in a vacuum would not cease. He viewed inclination as a permanent force whose effect is dissipated by external forces such as air resistance.
The theory of motion presented by Avicenna was probably influenced by the 6th-century Alexandrian scholar John Philoponus. Avicenna's is a less sophisticated variant of the theory of impetus developed by Buridan in the 14th century. It is unclear if Buridan was influenced by Avicenna, or by Philoponus directly. In optics, Avicenna was among those who argued that light had a speed, observing that "if the perception of light is due to the emission of some sort of particles by a luminous source, the speed of light must be finite." He also provided a wrong explanation of the rainbow phenomenon. Carl Benjamin Boyer described Avicenna's ("Ibn Sīnā") theory on the rainbow as follows: In 1253, a Latin text entitled "Speculum Tripartitum" stated the following regarding Avicenna's theory on heat: Psychology. Avicenna's legacy in classical psychology is primarily embodied in the "Kitab al-nafs" parts of his "Kitab al-shifa" ("The Book of Healing") and "Kitab al-najat" ("The Book of Deliverance"). These were known in Latin under the title De Anima (treatises "on the soul"). Notably, Avicenna develops what is called the Flying Man argument in the Psychology of "The Cure" I.1.7 as defence of the argument that the soul is without quantitative extension, which has an affinity with Descartes's "cogito" argument (or what phenomenology designates as a form of an "epoche").
Avicenna's psychology requires that connection between the body and soul be strong enough to ensure the soul's individuation, but weak enough to allow for its immortality. Avicenna grounds his psychology on physiology, which means his account of the soul is one that deals almost entirely with the natural science of the body and its abilities of perception. Thus, the philosopher's connection between the soul and body is explained almost entirely by his understanding of perception; in this way, bodily perception interrelates with the immaterial human intellect. In sense perception, the perceiver senses the form of the object; first, by perceiving features of the object by our external senses. This sensory information is supplied to the internal senses, which merge all the pieces into a whole, unified conscious experience. This process of perception and abstraction is the nexus of the soul and body, for the material body may only perceive material objects, while the immaterial soul may only receive the immaterial, universal forms. The way the soul and body interact in the final abstraction of the universal from the concrete particular is the key to their relationship and interaction, which takes place in the physical body.
The soul completes the action of intellection by accepting forms that have been abstracted from matter. This process requires a concrete particular (material) to be abstracted into the universal intelligible (immaterial). The material and immaterial interact through the Active Intellect, which is a "divine light" containing the intelligible forms. The Active Intellect reveals the universals concealed in material objects much like the sun makes colour available to our eyes. Other contributions. Astronomy and astrology. Avicenna wrote an attack on astrology titled "Missive on the Champions of the Rule of the Stars" () in which he cited passages from the Quran to dispute the power of astrology to foretell the future. He believed that each classical planet had some influence on the Earth but argued against current astrological practices. Avicenna's astronomical writings had some influence on later writers, although in general his work could be considered less developed than that of ibn al-Haytham or al-Biruni. One important feature of his writing is that he considers mathematical astronomy a separate discipline from astrology. He criticized Aristotle's view of the stars receiving their light from the Sun, stating that the stars are self-luminous, and believed that the planets are also self-luminous. He claimed to have observed the transit of Venus. This is possible as there was a transit on 24 May 1032, but ibn Sina did not give the date of his observation and modern scholars have questioned whether he could have observed the transit from his location at that time; he may have mistaken a sunspot for Venus. He used his transit observation to help establish that Venus was, at least sometimes, below the Sun in the geocentric model, i.e. the sphere of Venus comes before the sphere of the Sun when moving out from the Earth.
He also wrote the "Summary of the Almagest" based on Ptolemy's "Almagest" with an appended treatise "to bring that which is stated in the Almagest and what is understood from Natural Science into conformity". For example, ibn Sina considers the motion of the solar apsis, which Ptolemy had taken to be fixed. Chemistry. Avicenna was first to derive the attar of flowers from distillation and used steam distillation to produce essential oils such as rose essence, which he used as aromatherapeutic treatments for heart conditions. Unlike al-Razi, Avicenna explicitly disputed the theory of the transmutation of substances commonly believed by alchemists: Four works on alchemy attributed to Avicenna were translated into Latin as: was the most influential, having influenced later medieval chemists and alchemists such as Vincent of Beauvais. However, Anawati argues (following Ruska) that the de Anima is a fake by a Spanish author. Similarly the Declaratio is believed not to be actually by Avicenna. The third work ("The Book of Minerals") is agreed to be Avicenna's writing, adapted from the "Kitab al-Shifa" ("Book of the Remedy"). Avicenna classified minerals into stones, fusible substances, sulfurs and salts, building on the ideas of Aristotle and Jabir. The "epistola de Re recta" is somewhat less sceptical of alchemy; Anawati argues that it is by Avicenna, but written earlier in his career when he had not yet firmly decided that transmutation was impossible.
Poetry. Almost half of Avicenna's works are versified. His poems appear in both Arabic and Persian. As an example, Edward Granville Browne claims that the following Persian verses are incorrectly attributed to Omar Khayyám, and were originally written by Ibn Sīnā: Legacy. Classical Islamic civilization. Robert Wisnovsky, a scholar of Avicenna attached to McGill University, says that "Avicenna was the central figure in the long history of the rational sciences in Islam, particularly in the fields of metaphysics, logic and medicine" but that his works did not only have an influence in these "secular" fields of knowledge alone, as "these works, or portions of them, were read, taught, copied, commented upon, quoted, paraphrased and cited by thousands of post-Avicennian scholars—not only philosophers, logicians, physicians and specialists in the mathematical or exact sciences, but also by those who specialized in the disciplines of ʿilm al-kalām (rational theology, but understood to include natural philosophy, epistemology and philosophy of mind) and usūl al-fiqh (jurisprudence, but understood to include philosophy of law, dialectic, and philosophy of language)."
Medieval and Renaissance Europe. As early as the 14th century when Dante Alighieri depicted him in Limbo alongside the virtuous non-Christian thinkers in his "Divine Comedy" such as Virgil, Averroes, Homer, Horace, Ovid, Lucan, Socrates, Plato and Saladin. Avicenna has been recognized by both East and West as one of the great figures in intellectual history. Johannes Kepler cites Avicenna's opinion when discussing the causes of planetary motions in Chapter 2 of "Astronomia Nova". George Sarton, the author of "The History of Science", described Avicenna as "one of the greatest thinkers and medical scholars in history" and called him "the most famous scientist of Islam and one of the most famous of all races, places, and times". He was one of the Islamic world's leading writers in the field of medicine. Along with Rhazes, Abulcasis, Ibn al-Nafis and al-Ibadi, Avicenna is considered an important compiler of early Muslim medicine. He is remembered in the Western history of medicine as a major historical figure who made important contributions to medicine and the European Renaissance. His medical texts were unusual in that where controversy existed between Galen and Aristotle's views on medical matters (such as anatomy), he preferred to side with Aristotle, where necessary updating Aristotle's position to take into account post-Aristotelian advances in anatomical knowledge. Aristotle's dominant intellectual influence among medieval European scholars meant that Avicenna's linking of Galen's medical writings with Aristotle's philosophical writings in the "Canon of Medicine" (along with its comprehensive and logical organisation of knowledge) significantly increased Avicenna's importance in medieval Europe in comparison to other Islamic writers on medicine. His influence following translation of the "Canon" was such that from the early fourteenth to the mid-sixteenth centuries he was ranked with Hippocrates and Galen as one of the acknowledged authorities, ("prince of physicians").
Modern reception. Institutions in a variety of counties have been named after Avicenna in honour of his scientific accomplishments, including the Avicenna Mausoleum and Museum, Bu-Ali Sina University, Avicenna Research Institute and Ibn Sina Academy of Medieval Medicine and Sciences. There is also a crater on the Moon named Avicenna. The Avicenna Prize, established in 2003, is awarded every two years by UNESCO and rewards individuals and groups for their achievements in the field of ethics in science. The Avicenna Directories (2008–2015; now the World Directory of Medical Schools) list universities and schools where doctors, public health practitioners, pharmacists and others, are educated. The original project team stated: In June 2009, Iran donated a "Persian Scholars Pavilion" to the United Nations Office in Vienna. It now sits in the Vienna International Center. In popular culture. The 1982 Soviet film "Youth of Genius" () by recounts Avicenna's younger years. The film is set in Bukhara at the turn of the millennium.
In Louis L'Amour's 1985 historical novel "The Walking Drum", Kerbouchard studies and discusses Avicenna's "The Canon of Medicine". In his book "The Physician" (1988) Noah Gordon tells the story of a young English medical apprentice who disguises himself as a Jew to travel from England to Persia and learn from Avicenna, the great master of his time. The novel was adapted into a feature film, "The Physician", in 2013. Avicenna was played by Ben Kingsley. List of works. The treatises of Avicenna influenced later Muslim thinkers in many areas including theology, philology, mathematics, astronomy, physics and music. His works numbered almost 450 volumes on a wide range of subjects, of which around 240 have survived. In particular, 150 volumes of his surviving works concentrate on philosophy and 40 of them concentrate on medicine. His most famous works are "The Book of Healing", and "The Canon of Medicine". Avicenna wrote at least one treatise on alchemy, but several others have been falsely attributed to him. His "Logic", "Metaphysics", "Physics", and "De Caelo", are treatises giving a synoptic view of Aristotelian doctrine, though "Metaphysics" demonstrates a significant departure from the brand of Neoplatonism known as Aristotelianism in Avicenna's world; Arabic philosophers have hinted at the idea that Avicenna was attempting to "re-Aristotelianise" Muslim philosophy in its entirety, unlike his predecessors, who accepted the conflation of Platonic, Aristotelian, Neo- and Middle-Platonic works transmitted into the Muslim world.
The "Logic" and "Metaphysics" have been extensively reprinted, the latter, e.g., at Venice in 1493, 1495 and 1546. Some of his shorter essays on medicine, logic, etc., take a poetical form (the poem on logic was published by Schmoelders in 1836). Two encyclopedic treatises, dealing with philosophy, are often mentioned. The larger, "Al-Shifa"' ("Sanatio"), exists nearly complete in manuscript in the Bodleian Library and elsewhere; part of it on the "De Anima" appeared at Pavia (1490) as the "Liber Sextus Naturalium", and the long account of Avicenna's philosophy given by Muhammad al-Shahrastani seems to be mainly an analysis, and in many places a reproduction, of the Al-Shifa'. A shorter form of the work is known as the An-najat ("Liberatio"). The Latin editions of part of these works have been modified by the corrections which the monastic editors confess that they applied. There is also a ("hikmat-al-mashriqqiyya", in Latin "Philosophia Orientalis"), mentioned by Roger Bacon, the majority of which is lost in antiquity, which according to Averroes was pantheistic in tone.
Avicenna's works further include: Persian works. Avicenna's most important Persian work is the "Danishnama" (, "Book of Knowledge". Avicenna created a new scientific vocabulary that had not previously existed in Persian. The "Danishnama" covers such topics as logic, metaphysics, music theory and other sciences of his time. It has been translated into English by Parwiz Morewedge in 1977. The book is also important in respect to Persian scientific works. "Andar Dānish-i Rag" (, "On the Science of the Pulse") contains nine chapters on the science of the pulse and is a condensed synopsis. Persian poetry from Avicenna is recorded in various manuscripts and later anthologies such as "Nozhat al-Majales".
The Ashes The Ashes is a Test cricket series played biennially between England and Australia. The term originated in a satirical obituary published in a British newspaper, "The Sporting Times", immediately after Australia's 1882 victory at The Oval, its first Test win on English soil. The obituary stated that English cricket had died, and that "the body will be cremated and the ashes taken to Australia". The mythical ashes immediately became associated with the 1882–83 series played in Australia, before which the English captain Ivo Bligh had vowed to "regain those ashes". The English media therefore dubbed the tour "the quest to regain the Ashes". After England won two of the three Tests on the tour, a small urn was presented to Bligh in Melbourne. The contents of the urn are reputed to be the ashes of a wooden bail, and were humorously described as "the ashes of Australian cricket". It is not clear whether that "tiny silver urn" is the same as the small terracotta urn given to Marylebone Cricket Club (MCC) by Bligh's widow after his death in 1927.
The Ashes urn has never been the official trophy of the series, having been a personal gift to Bligh, but replicas of the urn have often been held aloft by the winning team as a symbol of their victory. Since the 1998–99 Ashes series, the Ashes Trophy, a Waterford Crystal trophy modelled on the Ashes urn, has been presented to the winners of the series. Irrespective of which side holds the trophy, the original urn remains in the MCC Museum at Lord's. It has been taken to Australia twice to be put on touring display, as part of the Australian Bicentenary celebrations in 1988 and to accompany the Ashes series in 2006–07. Ashes series have usually consisted of five Tests, hosted in turn by England and Australia approximately every two years. The Ashes are regarded as being held by the team that most recently won the series. If the series is drawn, the team that currently holds the Ashes "retains" the trophy. There have been 73 Ashes series. Australia have won 34 and retained six times from draws (40); England have won 32 and retained once (33). 1882 origins.
The first Test match between England and Australia was played in Melbourne, Australia, in 1877, though the Ashes legend started later, after the ninth Test, played in 1882. On their tour of England that year the Australians played just one Test, at the Oval in London. It was a low-scoring affair on a difficult wicket. Australia made a mere 63 runs in their first innings, and England, led by A. N. Hornby, took a 38-run lead with a total of 101. In their second innings, Australia, boosted by a spectacular 55 runs off 60 deliveries from Hugh Massie, managed 122, which left England only 85 runs to win. The Australians were greatly demoralised by the manner of their second-innings collapse, but fast bowler Fred Spofforth, spurred on by the gamesmanship of his opponents, in particular W. G. Grace, refused to give in. "This thing can be done," he declared. Spofforth went on to devastate the English batting, taking his final four wickets for only two runs to leave England just eight runs short of victory. When Ted Peate, England's last batsman, came to the crease, his side needed just ten runs to win, but Peate managed only two before he was bowled by Harry Boyle. An astonished Oval crowd fell silent, struggling to believe that England could possibly have lost on home soil. When it finally sank in, the crowd swarmed onto the field, cheering loudly and chairing Boyle and Spofforth to the pavilion.
When Peate returned to the pavilion he was reprimanded by his captain for not allowing his partner, Charles Studd (one of the best batsmen in England, having already hit two centuries that season against the colonists), to get the runs. Peate humorously replied, "I had no confidence in Mr Studd, sir, so thought I had better do my best." The momentous defeat was widely recorded in the British press, which praised the Australians for their plentiful "pluck" and berated the Englishmen for their lack thereof. A celebrated poem appeared in "Punch" on Saturday, 9 September. The first verse, quoted most frequently, reads: <poem> Well done, Cornstalks! Whipt us Fair and square, Was it luck that tript us? Was it scare? Kangaroo Land's 'Demon', or our own Want of 'devil', coolness, nerve, backbone? </poem> On 31 August, in the Charles Alcock-edited magazine "Cricket: A Weekly Record of The Game", there appeared a mock obituary: On 2 September a more celebrated mock obituary, written by Reginald Shirley Brooks, appeared in "The Sporting Times". It read:
Ivo Bligh promised that on the 1882–83 tour of Australia, he would, as England's captain, "recover those Ashes". He spoke of them several times over the course of the tour, and the Australian media quickly caught on. The three-match series resulted in a two-one win to England, notwithstanding a fourth match, won by the Australians, whose status remains a matter of ardent dispute. In the 20 years following Bligh's campaign the term "the Ashes" largely disappeared from public use. There is no indication that this was the accepted name for the series, at least not in England. The term became popular again in Australia first, when George Giffen, in his memoirs ("With Bat and Ball", 1899), used the term as if it were well known. The true and global revitalisation of interest in the concept dates from 1903, when Pelham Warner took a team to Australia with the promise that he would regain "the ashes". As had been the case on Bligh's tour 20 years before, the Australian media latched fervently onto the term and, this time, it stuck. Having fulfilled his promise, Warner published a book entitled "How We Recovered the Ashes". Although the origins of the term are not referred to in the text, the title served (along with the general hype created in Australia) to revive public interest in the legend. The first mention of "the Ashes" in "Wisden Cricketers' Almanack" occurs in 1905, while "Wisden"'s first account of the legend is in the 1922 edition.
Urn. It took many years before the contests between England and Australia were consistently called "The Ashes", and so there was no concept of either a trophy or a physical representation of the ashes. As late as 1925, the following verse appeared in "The Cricketers Annual": <poem> So here's to Chapman, Hendren and Hobbs, Gilligan, Woolley and Hearne May they bring back to the Motherland, The ashes which have no urn! </poem> Nevertheless, several attempts had been made to embody the Ashes in a physical memorial. Examples include one presented to Warner in 1904, another to Australian captain M. A. Noble in 1909, and another to Australian captain W. M. Woodfull in 1934. The oldest, and the one to enjoy enduring fame, was the one presented to Bligh, later Lord Darnley, during the 1882–83 tour. The precise nature of the origin of this urn is a matter of dispute. Based on a statement by Darnley in 1894, it was believed that a group of Victorian ladies, including Darnley's later wife Florence Morphy, made the presentation after the victory in the Third Test in 1883. More recent researchers, in particular Ronald Willis and Joy Munns have studied the tour in detail and concluded that the presentation was made after a private cricket match played over Christmas 1882 when the English team were guests of Sir William Clarke, at his property "Rupertswood", in Sunbury, Victoria. This was before the matches had started. The prime evidence for this theory was provided by a descendant of Clarke.
In August 1926 Ivo Bligh (now Lord Darnley) displayed the Ashes urn at the "Morning Post" Decorative Art Exhibition held in the Central Hall, Westminster. He made the following statement about how he was given the urn: A more detailed account of how the Ashes were given to Ivo Bligh was outlined by his wife, the Countess of Darnley, in 1930 during a speech at a cricket luncheon. Her speech was reported by the "Times" as follows: There is another statement which is not totally clear made by Lord Darnley in 1921 about the timing of the presentation of the urn. He was interviewed in his home at Cobham Hall by Montague Grover and the report of this interview was as follows: He made a similar statement in 1926. The report of this statement in the "Brisbane Courier" was as follows: The contents of the urn are also problematic; they were variously reported to be the remains of a stump, bail or the outer casing of a ball, but in 1998 Darnley's 82-year-old daughter-in-law said they were the remains of her mother-in-law's veil, casting a further layer of doubt on the matter. However, during the tour of Australia in 2006/7, the MCC official accompanying the urn said the veil legend had been discounted, and it was now "95% certain" that the urn contains the ashes of a cricket bail. Speaking on Channel Nine TV on 25 November 2006, he said x-rays of the urn had shown the pedestal and handles were cracked, and repair work had to be carried out. The urn is made of terracotta and is about tall and may originally have been a perfume jar.
A label containing a six-line verse is pasted on the urn. This is the fourth verse of a song-lyric published in the "Melbourne Punch" on 1 February 1883: <poem> When Ivo goes back with the urn, the urn; Studds, Steel, Read and Tylecote return, return; The welkin will ring loud, The great crowd will feel proud, Seeing Barlow and Bates with the urn, the urn; And the rest coming home with the urn. </poem> In February 1883, just before the disputed Fourth Test, a velvet bag made by Mrs Ann Fletcher, the daughter of Joseph Hines Clarke and Marion Wright, both of Dublin, was given to Bligh to contain the urn. During Darnley's lifetime there was little public knowledge of the urn, and no record of a published photograph exists before 1921. "The Illustrated London News" published this photo in January 1921 (shown above). When Darnley died in 1927 his widow presented the urn to the Marylebone Cricket Club and that was the key event in establishing the urn as the physical embodiment of the legendary ashes. MCC first displayed the urn in the Long Room at Lord's and since 1953 in the MCC Cricket Museum at the ground. MCC's wish for it to be seen by as wide a range of cricket enthusiasts as possible has led to its being mistaken for an official trophy. It is in fact a private memento, and for this reason it is never awarded to either England or Australia, but is kept permanently in the MCC Cricket Museum where it can be seen together with the specially made red and gold velvet bag and the scorecard of the 1882 match.
Because the urn itself is so delicate, it has been allowed to travel to Australia only twice. The first occasion was in 1988 for a museum tour as part of the Australian Bicentenary celebrations; the second was for the 2006/7 Ashes series. The urn arrived on 17 October 2006, going on display at the Museum of Sydney. It then toured to other states, with the final appearance at the Tasmanian Museum and Art Gallery on 21 January 2007. In the 1990s, given Australia's long dominance of the Ashes and the popular acceptance of the Darnley urn as "the Ashes", the idea was mooted that the victorious team should be awarded the urn as a trophy and allowed to retain it until the next series. As its condition is fragile and it is a prized exhibit at the MCC Cricket Museum, the MCC would not agree. Furthermore, in 2002, Bligh's great-great-grandson Lord Clifton, the heir-apparent to the Earldom of Darnley, argued that the Ashes urn should not be returned to Australia because it belonged to his family and was given to the MCC only for safe keeping.
As a compromise, the MCC commissioned a larger replica of the urn in Waterford Crystal, known as the Ashes Trophy, to award to the winning team of each series starting with the 1998–99 Ashes. This did little to diminish the status of the Darnley urn as the most important icon in cricket, the symbol of this old and keenly fought contest. Series and matches. Quest to "recover those ashes". Later in 1882, following the famous Australian victory at The Oval, Bligh led an England team to Australia, as he said, to "recover those ashes". Publicity surrounding the series was intense, and it was at some time during this series that the Ashes urn was crafted. Australia won the First Test by nine wickets, but in the next two England were victorious. At the end of the Third Test, England were generally considered to have "won back the Ashes" 2–1. A fourth match was played, against a "United Australian XI", which was arguably stronger than the Australian sides that had competed in the previous three matches; this game, however, is not generally considered part of the 1882–83 series. It "is" counted as a Test, but as a standalone. This match ended in a victory for Australia. 1884 to 1896.
After Bligh's victory, there was an extended period of English dominance. The tours generally had fewer Tests in the 1880s and 1890s than people have grown accustomed to in more recent years, the first five-Test series taking place only in 1894–95. England lost only four Ashes Tests in the 1880s out of 23 played, and they won all the seven series contested. There was more chopping and changing in the teams, given that there was no official board of selectors for each country (in 1887–88, two separate English teams were on tour in Australia) and popularity with the fans varied. The 1890s games were more closely fought, Australia taking its first series win since 1882 with a 2–1 victory in 1891–92. But England dominated, winning the next three series to 1896 despite continuing player disputes. The 1894–95 series began in sensational fashion when England won the First Test at Sydney by just 10 runs having followed on. Australia had scored a massive 586 (Syd Gregory 201, George Giffen 161) and then dismissed England for 325. But England responded with 437 and then dramatically dismissed Australia for 166 with Bobby Peel taking 6 for 67. At the close of the second last day's play, Australia were 113–2, needing only 64 more runs. But heavy rain fell overnight and next morning the two slow left-arm bowlers, Peel and Johnny Briggs, were all but unplayable. England went on to win the series 3–2 after it had been all square before the Final Test, which England won by 6 wickets. The English heroes were Peel, with 27 wickets in the series at an average of 26.70, and Tom Richardson, with 32 at 26.53.
In 1896, England under the captaincy of W. G. Grace won the series 2–1, and this marked the end of England's longest period of Ashes dominance. 1897 to 1902. Australia resoundingly won the 1897–98 series by 4–1 under the captaincy of Harry Trott. His successor Joe Darling won the next three series in 1899, 1901–02, and the classic 1902 series, which became one of the most famous in the history of Test cricket. Five matches were played in 1902 but the first two were drawn after being hit by bad weather. In the First Test (the first played at Edgbaston), after scoring 376 England bowled out Australia for 36 (Wilfred Rhodes 7/17) and reduced them to 46–2 when they followed on. Australia won the Third and Fourth Tests at Bramall Lane and Old Trafford respectively. At Old Trafford, Australia won by just 3 runs after Victor Trumper had scored 104 on a "bad wicket", reaching his hundred before lunch on the first day. England won the last Test at The Oval by one wicket. Chasing 263 to win, they slumped to 48–5 before Gilbert Jessop's 104 gave them a chance. He reached his hundred in just 75 minutes. The last-wicket pair of George Hirst and Rhodes were required to score 15 runs for victory. When Rhodes joined him, Hirst reportedly said: "We'll get them in singles, Wilfred." In fact, they scored thirteen singles and a two.
The period of Darling's captaincy saw the emergence of outstanding Australian players such as Trumper, Warwick Armstrong, James Kelly, Monty Noble, Clem Hill, Hugh Trumble and Ernie Jones. Reviving the legend. After what the MCC saw as the problems of the earlier professional and amateur series they decided to take control of organising tours themselves, and this led to the first MCC tour of Australia in 1903–04. England won it against the odds, and Plum Warner, the England captain, wrote up his version of the tour in his book "How We Recovered The Ashes". The title of this book revived the Ashes legend and it was after this that England v Australia series were customarily referred to as "The Ashes". 1905 to 1912. England and Australia were evenly matched until the outbreak of the First World War in 1914. Five more series took place between 1905 and 1912. In 1905, England's captain Stanley Jackson not only won the series 2–0, but also won the toss in all five matches and headed both the batting and the bowling averages. Monty Noble led Australia to victory in both 1907–08 and 1909. Then England won in 1911–12 by four matches to one. Jack Hobbs establishing himself as England's first-choice opening batsman with three centuries, while Frank Foster (32 wickets at 21.62) and Sydney Barnes (34 wickets at 22.88) formed a formidable bowling partnership.
England retained the Ashes when it won the 1912 Triangular Tournament, which also featured South Africa. The Australian touring party had been severely weakened by a dispute between the board and players that caused Clem Hill, Victor Trumper, Warwick Armstrong, Tibby Cotter, Sammy Carter and Vernon Ransford to be omitted. 1920 to 1933. After the war, Australia took firm control of both the Ashes and world cricket. For the first time, the tactic of using two express bowlers in tandem paid off as Jack Gregory and Ted McDonald crippled the English batting on a regular basis. Australia recorded overwhelming victories both in England and on home soil. It won the first eight matches in succession including a 5–0 whitewash in 1920–1921 at the hands of Warwick Armstrong's team. The ruthless and belligerent Armstrong led his team back to England in 1921 where his men lost only two games late in the tour to narrowly miss out of being the first team to complete a tour of England without defeat. England won only one Test out of 15 from the end of the war until 1925.
In a rain-hit series in 1926, England managed to eke out a 1–0 victory with a win in the final Test at The Oval. Because the series was at stake, the match was to be "timeless", i.e., played to a finish. Australia had a narrow first innings lead of 22. Jack Hobbs and Herbert Sutcliffe took the score to 49–0 at the end of the second day, a lead of 27. Heavy rain fell overnight, and next day the pitch soon developed into a traditional sticky wicket. England seemed doomed to be bowled out cheaply and to lose the match. In spite of the very difficult batting conditions, however, Hobbs and Sutcliffe took their partnership to 172 before Hobbs was out for exactly 100. Sutcliffe went on to make 161 and England won the game comfortably. Australian captain Herbie Collins was stripped of all captaincy positions down to club level, and some accused him of throwing the match. Australia's ageing post-war team broke up after 1926, with Collins, Charlie Macartney and Warren Bardsley all departing, and Gregory breaking down at the start of the 1928–29 series.
Despite the debut of Donald Bradman, the inexperienced Australians, led by Jack Ryder, were heavily defeated, losing 4–1. England had a very strong batting side, with Wally Hammond contributing 905 runs at an average of 113.12, and Hobbs, Sutcliffe and Patsy Hendren all scoring heavily; the bowling was more than adequate, without being outstanding. In 1930, Bill Woodfull led an extremely inexperienced team to England. Bradman fulfilled his promise in the 1930 series when he scored 974 runs at 139.14, which remains a world record Test series aggregate. A modest Bradman can be heard in a 1930 recording saying "I have always endeavoured to do my best for the side, and the few centuries that have come my way have been achieved in the hope of winning matches. My one idea when going into bat was to make runs for Australia." In the Headingley Test, he made 334, reaching 309* at the end of the first day, including a century before lunch. Bradman himself thought that his 254 in the preceding match, at Lord's, was a better innings. England managed to stay in contention until the deciding final Test at The Oval, but yet another double hundred by Bradman, and 7/92 by Percy Hornibrook in England's second innings, enabled Australia to win by an innings and take the series 2–1. Clarrie Grimmett's 29 wickets at 31.89 for Australia in this high-scoring series were also important.
Australia had one of the strongest batting line-ups ever in the early 1930s, with Bradman, Archie Jackson, Stan McCabe, Bill Woodfull, Bill Ponsford and Jack Fingleton. It was the prospect of bowling at this line-up that caused England's 1932–33 captain Douglas Jardine to adopt the tactic of fast leg theory, better known as Bodyline. Jardine instructed his fast bowlers, most notably Harold Larwood and Bill Voce, to bowl at the bodies of the Australian batsmen, with the goal of forcing them to defend their bodies with their bats, thus providing easy catches to a stacked leg-side field. Jardine insisted that the tactic was legitimate and called it "leg theory" but it was widely disparaged by its opponents, who dubbed it "Bodyline" (from "on the line of the body"). Although England decisively won the Ashes 4–1, Bodyline caused such a furore in Australia that diplomats had to intervene to prevent serious harm to Anglo-Australian relations, and the MCC eventually changed the Laws of cricket to curtail the number of leg side fielders.
Jardine's comment was: "I've not travelled 6,000 miles to make friends. I'm here to win the Ashes". Some of the Australians wanted to use Bodyline in retaliation, but Woodfull flatly refused. He famously told England manager Pelham Warner, "There are two teams out there. One is playing cricket; the other is making no attempt to do so" after the latter had come into the Australian rooms to express sympathy after a Larwood bouncer had struck the Australian skipper in the heart and felled him. 1934 to 1953. On the batting-friendly wickets that prevailed in the late 1930s, most Tests up to the Second World War still gave results. It should be borne in mind that Tests in Australia prior to the war were all played to a finish, with many batting records set during this period. The 1934 Ashes series began with the notable absence of Larwood, Voce and Jardine. The MCC had made it clear, in light of the revelations of the bodyline series, that these players would not face Australia. The MCC, although it had earlier condoned and encouraged bodyline tactics in the 1932–33 series, laid the blame on Larwood when relations turned sour. Larwood was forced by the MCC to either apologise or be removed from the Test side. He went for the latter.
Australia recovered the Ashes in 1934 and held them until 1953, though no Test cricket was played during the Second World War. As in 1930, the 1934 series was decided in the final Test at The Oval. Australia, batting first, posted a massive 701 in the first innings. Bradman (244) and Ponsford (266) were in record-breaking form with a partnership of 451 for the second wicket. England eventually faced a massive 707-run target for victory and failed, Australia winning the series 2–1. This made Woodfull the only captain to regain the Ashes and he retired upon his return to Australia. In 1936–37 Bradman succeeded Woodfull as Australian captain. He started badly, losing the first two Tests heavily after Australia were caught on sticky wickets. However, the Australians fought back and Bradman won his first series in charge 3–2. The 1938 series was a high-scoring affair with two high-scoring draws, resulting in a 1–1 result, Australia retaining the Ashes. After the first two matches ended in stalemate and the Third Test at Old Trafford never started due to rain, Australia then scraped home by five wickets inside three days in a low-scoring match at Headingley to retain the urn. In the timeless Fifth Test at The Oval, the highlight was Len Hutton's then world-record score of 364 as England made 903-7 declared. Bradman and Jack Fingleton injured themselves during Hutton's marathon effort, and with only nine men, Australia fell to defeat by an innings and 579 runs, the heaviest in Test history.
The Ashes resumed after the war when England toured in 1946–47 and, as in 1920–21, found that Australia had made the better post-war recovery. Still captained by Bradman and now featuring the potent new-ball partnership of Ray Lindwall and Keith Miller, Australia were convincing 3–0 winners. Aged 38 and having been unwell during the war, Bradman had been reluctant to play. He batted unconvincingly and reached 28 when he hit a ball to Jack Ikin; England believed it was a catch, but Bradman stood his ground, believing it to be a bump ball. The umpire ruled in the Australian captain's favour and he appeared to regain his fluency of yesteryear, scoring 187. Australia promptly seized the initiative, won the First Test convincingly and inaugurated a dominant post-war era. The controversy over the Ikin catch was one of the biggest disputes of the era. In 1948, Australia set new standards, completely outplaying its hosts to win 4–0 with one draw. This Australian team, led by Bradman, who turned 40 during his final tour of England, has gone down in history as "The Invincibles". Playing 34 matches on tour—three of which were not first-class—and including the five Tests, they remained unbeaten, winning 27 and drawing 7.
Bradman's men were greeted by packed crowds across the country, and records for Test attendances in England were set in the Second and Fourth Tests at Lord's and Headingley respectively. Before a record attendance of spectators at Headingley, Australia set a world record by chasing down 404 on the last day for a seven-wicket victory. The 1948 series ended with one of the most poignant moments in cricket history, as Bradman played his final innings for Australia in the Fifth Test at The Oval, needing to score only four runs to end with a career batting average of exactly 100. However, Bradman made a second-ball duck, bowled by an Eric Hollies googly that sent him into retirement with a career average of 99.94. Bradman was succeeded as Australian captain by Lindsay Hassett, who led the team to a 4–1 series victory in 1950–51. The series was not as one-sided as the number of wins suggest, with several tight matches. The tide finally turned in 1953 when England won the final Test at The Oval to take the series 1–0, having narrowly avoided defeat in the preceding Test at Headingley. This was the beginning of one of the greatest periods in English cricket history with players such as captain Len Hutton, batsmen Denis Compton, Peter May, Tom Graveney, Colin Cowdrey, bowlers Fred Trueman, Brian Statham, Alec Bedser, Jim Laker, Tony Lock, wicket-keeper Godfrey Evans and all-rounder Trevor Bailey. 1954 to 1971.
In 1954–55, Australia's batsmen had no answer to the pace of Frank Tyson and Statham. After winning the First Test by an innings after being controversially sent in by Hutton, Australia lost its way and England took a hat-trick of victories to win the series 3–1. A dramatic series in 1956 saw a record that will probably never be beaten: off-spinner Jim Laker's monumental effort at Old Trafford when he bowled 68 of 191 overs to take 19 out of 20 possible Australian wickets in the Fourth Test. It was Australia's second consecutive innings defeat in a wet summer, and the hosts were in strong positions in the two drawn Tests, in which half the playing time was washed out. Bradman rated the team that won the series 2–1 as England's best ever. England's dominance was not to last. Australia won 4–0 in 1958–59, having found a high-quality spinner of their own in new skipper Richie Benaud, who took 31 wickets in the five-Test series, and paceman Alan Davidson, who took 24 wickets at 19.00. The series was overshadowed by the furore over various Australian bowlers, most notably Ian Meckiff, whom the English management and media accused of illegally throwing Australia to victory.
In 1961, Australia won a hard-fought series 2–1, their first Ashes series win in England for 13 years. After narrowly winning the Second Test at Lord's, dubbed "The Battle of the Ridge" because of a protrusion on the pitch that caused erratic bounce, Australia mounted a comeback on the final day of the Fourth Test at Old Trafford and sealed the series with Richie Benaud taking 6-70 during the English runchase. The tempo of the play changed over the next four series in the 1960s, held in 1962–63, 1964, 1965–66 and 1968. The powerful array of bowlers that both countries boasted in the preceding decade moved into retirement, and their replacements were of lesser quality, making it more difficult to force a result. England failed to win any series during the 1960s, a period dominated by draws as teams found it more prudent to save face than risk losing. Of the 20 Tests played during the four series, Australia won four and England three. As they held the Ashes, Australia's captains Bob Simpson and Bill Lawry were happy to adopt safety-first tactics and their strategy of sedate batting saw many draws. During this period, spectator attendances dropped and media condemnation increased, but Simpson and Lawry flatly disregarded the public dissatisfaction.
It was in the 1960s that the bipolar dominance of England and Australia in world cricket was seriously challenged for the first time. West Indies defeated England twice in the mid-1960s and South Africa, in two series before they were banned for apartheid, completely outplayed Australia 3–1 and 4–0. Australia had lost 2–1 during a tour of the West Indies in 1964–65, the first time it had lost a series to any team other than England. In 1970–71, Ray Illingworth led England to a 2–0 win in Australia, mainly due to John Snow's fast bowling, and the prolific batting of Geoffrey Boycott and John Edrich. It was not until the last session of what was the 7th Test (one match having been abandoned without a ball bowled) that England's success was secured. Lawry was sacked after the Sixth Test after the selectors finally lost patience with Australia's lack of success and dour strategy. Lawry was not informed of the decision privately and heard his fate over the radio. 1972 to 1987. The 1972 series finished 2–2, with England under Illingworth retaining the Ashes.
In the 1974–75 series, with the England team breaking up and their best batsman Geoff Boycott refusing to play, Australian pace bowlers Jeff Thomson and Dennis Lillee wreaked havoc. A 4–1 result was a fair reflection as England were left shell shocked. England then lost the 1975 series 0–1, but at least restored some pride under new captain Tony Greig. Australia won the 1977 Centenary Test which was not an Ashes contest, but then a storm broke as Kerry Packer announced his intention to form World Series Cricket. WSC affected all Test-playing nations but it weakened Australia especially as the bulk of its players had signed up with Packer; the Australian Cricket Board (ACB) would not select WSC-contracted players and an almost completely new Test team had to be formed. WSC came after an era during which the duopoly of Australian and English dominance dissipated; the Ashes had long been seen as a cricket world championship but the rise of the West Indies in the late 1970s challenged that view. The West Indies would go on to record resounding Test series wins over Australia and England and dominated world cricket until the 1990s.
With Greig having joined WSC, England appointed Mike Brearley as its captain and he enjoyed great success against Australia. Largely assisted by the return of Boycott, Brearley's men won the 1977 series 3–0 and then completed an overwhelming 5–1 series win against an Australian side missing its WSC players in 1978–79. Allan Border made his Test debut for Australia in 1978–79. Brearley retired from Test cricket in 1980 and was succeeded by Ian Botham, who started the 1981 series as England captain, by which time the WSC split had ended. After Australia took a 1–0 lead in the first two Tests, Botham was forced to resign or was sacked (depending on the source). Brearley surprisingly agreed to be reappointed before the Third Test at Headingley. This was a remarkable match in which Australia looked certain to take a 2–0 series lead after it had forced England to follow-on 227 runs behind. England, despite being 135 for 7, produced a second innings total of 356, Botham scoring 149*. Chasing just 130, Australia were sensationally dismissed for 111, Bob Willis taking 8–43. It was the first time since 1894–95 that a team following on had won a Test match. Under Brearley's leadership, England went on to win the next two matches before a drawn final match at The Oval. This series became known as 'Botham's Ashes' for his extraordinary feats with both bat and ball, after being dismissed as captain.
In 1982–83 Australia had Greg Chappell back from WSC as captain, while the England team was weakened by the enforced omission of their South African tour rebels, particularly Graham Gooch and John Emburey. Australia went 2–0 up after three Tests, but England won the Fourth Test by 3 runs (after a 70-run last wicket stand) to set up the final decider, which was drawn. In 1985, David Gower's England team was strengthened by the return of Gooch and Emburey as well as the emergence at international level of Tim Robinson and Mike Gatting. Australia, now captained by Allan Border, had itself been weakened by a rebel South African tour, the loss of Terry Alderman being a particular factor. England won 3–1. Despite suffering heavy defeats against the West Indies during the 1980s, England continued to do well in the Ashes. Mike Gatting was the captain in 1986–87 but his team started badly and attracted some criticism. Then Chris Broad scored three hundreds in successive Tests and bowling successes from Graham Dilley and Gladstone Small meant England won the series 2–1. 1989 to 2005.
The Australian team of 1989 was comparable to the great Australian teams of the past, and resoundingly defeated England 4–0. Well led by Allan Border, the team included the young cricketers Mark Taylor, Merv Hughes, David Boon, Ian Healy and Steve Waugh, who were all to prove long-serving and successful Ashes competitors. England, now led once again by David Gower, suffered from injuries and poor form. During the Fourth Test news broke that prominent England players had agreed to take part in a "rebel tour" of South Africa the following winter; three of them (Tim Robinson, Neil Foster and John Emburey) were playing in the match, and were subsequently dropped from the England side. Australia reached a cricketing peak in the 1990s and early 2000s, coupled with a general decline in England's fortunes. After re-establishing its credibility in 1989, Australia underlined its superiority with victories in the 1990–91, 1993, 1994–95, 1997, 1998–99, 2001 and 2002–03 series, all by convincing margins. Great Australian players in the early years included batsmen Border, Boon, Taylor and Steve Waugh. The captaincy passed from Border to Taylor in the mid-1990s and then to Steve Waugh before the 2001 series. In the latter part of the 1990s Waugh himself, along with his twin brother Mark, scored heavily for Australia and fast bowlers Glenn McGrath and Jason Gillespie made a serious impact, especially the former. The wicketkeeper-batsman position was held by Ian Healy for most of the 1990s and by Adam Gilchrist from 2001 to 2006–07. In the 2000s, batsmen Justin Langer, Damien Martyn and Matthew Hayden became noted players for Australia. But the most dominant Australian player was leg-spinner Shane Warne, whose first delivery in Ashes cricket in 1993, to dismiss Mike Gatting, became known as the Ball of the Century.
Australia's record between 1989 and 2005 had a significant impact on the statistics between the two sides. Before the 1989 series began, the win–loss ratio was almost even, with 87 test wins for Australia to England's 86, 74 tests having been drawn. By the 2005 series Australia's test wins had increased to 115 whereas England's had increased to only 93 (with 82 draws). In the period between 1989 and the beginning of the 2005 series, the two sides had played 43 times; Australia winning 28 times, England 7 times, with 8 draws. Only a single England victory had come in a match in which the Ashes were still at stake, namely the First Test of the 1997 series. All others were consolation victories when the Ashes had been secured by Australia. 2005 to 2015. England were undefeated in Test matches through the 2004 calendar year. This elevated them to second in the ICC Test Championship. Hopes that the 2005 Ashes series would be closely fought proved well-founded, the series remaining undecided as the closing session of the final Test began. Experienced journalists including Richie Benaud rated the series as the most exciting in living memory. It has been compared with the great series of the distant past, such as 1894–95 and 1902.
The First Test at Lord's was convincingly won by Australia, but in the remaining four matches the teams were evenly matched and England fought back to win the Second Test by 2 runs, the smallest winning margin in Ashes history, and the second-smallest in all Tests. The rain-affected Third Test ended with the last two Australian batsmen holding out for a draw; and England won the Fourth Test by three wickets after forcing Australia to follow-on for the first time in 191 Tests. A draw in the final Test gave England victory in an Ashes series for the first time in 18 years and their first Ashes victory at home since 1985. Australia regained the Ashes on its home turf in the 2006–07 series with a convincing 5–0 victory, only the second time an Ashes series had been won by that margin. Shane Warne, Glenn McGrath and Justin Langer retired from Test cricket after that series, while Damien Martyn retired during the series. The 2009 series began with a tense draw in the First Test at SWALEC Stadium in Cardiff, with England's last-wicket batsmen James Anderson and Monty Panesar surviving 69 balls. England then achieved its first Ashes win at Lord's since 1934 to go 1–0 up. After a rain-affected draw at Edgbaston, the fourth match at Headingley was convincingly won by Australia by an innings and 80 runs to level the series. Finally, England won the Fifth Test at The Oval by a margin of 197 runs to regain the Ashes. Andrew Flintoff retired from Test cricket soon afterwards.
The 2010–11 series was played in Australia. The First Test at Brisbane ended in a draw, but England won the Second Test, at Adelaide, by an innings and 71 runs. Australia came back with a victory at Perth in the Third Test. In the Fourth Test at Melbourne Cricket Ground, England batting second scored 513 to defeat Australia (98 and 258) by an innings and 157 runs. This gave England an unbeatable 2–1 lead in the series and so it retained the Ashes. England went on to win the series 3–1, beating Australia by an innings and 83 runs at Sydney in the Fifth Test, including their highest innings total since 1938 (644). England's series victory was its first on Australian soil for 24 years. The 2010–11 Ashes series was the only one in which a team had won three Tests by innings margins and it was the first time England had scored 500 or more four times in a single series. England opener Cook scored 766 runs at average 127.66 in the series, the most dominant batsman in an Ashes series since Bradman in 1930. Australia's build-up to the 2013 Ashes series was far from ideal. Darren Lehmann took over as coach from Mickey Arthur following a string of poor results. A batting line-up weakened by the previous year's retirements of former captain Ricky Ponting and Mike Hussey was also shorn of opener David Warner, who was suspended for the start of the series following an off-field incident. England won a closely fought First Test by 14 runs, despite 19-year-old debutant Ashton Agar making a world-record 98 for a number 11 in the first innings. England then won a very one-sided Second Test by 347 runs while the rain-affected Third Test, held at a newly refurbished Old Trafford, was drawn, ensuring that England retained the Ashes. England won the Fourth Test by 74 runs after Australia lost their last eight second-innings wickets for only 86 runs. The final Test was drawn, giving England a 3–0 series win.
In the second of two Ashes series held in 2013 (the series ended in 2014), this time hosted by Australia, the home team won the series five test matches to nil. This was the third time Australia has completed a clean sweep (or "whitewash") in Ashes history, a feat never matched by England. All six Australian specialist batsmen scored more runs than any Englishman with 10 centuries among them, with only debutant Ben Stokes scoring a century for England. Mitchell Johnson took 37 English wickets at 13.97 and Ryan Harris 22 wickets at 19.31 in the 5-Test series. Only Stuart Broad and all-rounder Stokes bowled effectively for England, with their spinner Graeme Swann retiring due to a chronic elbow injury after the decisive Third Test. Australia came into the 2015 Ashes series in England as favourites to retain the Ashes. Although England won the first Test in Cardiff, Australia won comfortably in the second Test at Lords. In the next two Tests, the Australian batsmen struggled, being bowled out for 136 in the first innings at Edgbaston, with England proceeding to win by eight wickets. This was followed by Australia being bowled out for 60 as Stuart Broad took 8 for 15 in the first innings at Trent Bridge, the quickest – in terms of balls faced – a team has been bowled out in the first innings of a Test match. With victory by an innings and 78 runs on the morning of the third day of the Fourth Test, England regained the Ashes. 2017 to present.
During the buildup, the 2017–18 Ashes series was regarded as a turning point for both sides. Australia were criticised for being too reliant on captain Steve Smith and vice-captain David Warner, while England was said to have a shoddy middle to lower order. Off the field, England all-rounder Ben Stokes was ruled out of the side indefinitely due to a police investigation. Australia won the first Test match in Brisbane by 10 wickets and the second Test at Adelaide by 120 runs in the first ever day-night Ashes test match. Australia regained The Ashes with an innings and 41 run win in the third Test at Perth; the final Ashes Test at the WACA Ground. Prior to the 2019 Ashes series, both teams were considered to have very strong bowling attacks but struggling batting orders. Australia had its top-order batsmen David Warner, Steve Smith and Cameron Bancroft available for international selection after being banned from international cricket for 9–12 months following the ball-tampering scandal in South Africa, during which time India had won its first ever Test series in Australia. However, Australia recovered to win the Test series against Sri Lanka 2–0.
Despite winning the Cricket World Cup in July 2019 for the first time, England had also been criticised for its fragile top-order in Tests. The retirement of opener Alastair Cook in August 2018 ensured potential top-order batsmen Rory Burns, Joe Denly and Jason Roy were able to secure a place in the side. Despite losing a Test series 2–1 in their tour of the West Indies, England then improved to win the one-off Test against Ireland, by 143 runs. The 2019 series was eventually drawn 2–2, with Australia retaining the Ashes. The 2021-22 Ashes series was played from December 2021 through January 2022, and featured the first Ashes Test match to be played in Tasmania, at Hobart's Bellerive Oval. Australia retained the Ashes in the 2021–22 Ashes series, after comfortably beating England 4–0. England were the hosts of the five Test matches of the 2023 Ashes series. The series got off to a good start for Australia as they won the first two Tests to go 0–2 up. The hosts won the third Test to put the series at 1-2 for the visitors. England needed to win the fourth Test in a hope to not only level the series but prevent Australia from retaining the Ashes. The match looked good for England to win, but rain intervened on the last two days and forced a draw, thus Australia retained the Ashes with the series at 1–2 after four Tests. The fifth and final Test was played at The Oval. During the contest Stuart Broad announced that he would retire from cricket at the end of the match. England went on to win the final Test match to draw the series at 2-2.
Summary of results and statistics. In the 140 years since 1883, Australia have held the Ashes for approximately 84.5 years, and England for 55.5 years: Test results, up to and including 31 July 2023: Series results, up to and including 31 July 2023: A team must win a series to gain the right to hold the Ashes. A drawn series results in the previous holders retaining the Ashes. Ashes series have generally been played over five Test matches, although there have been four-match series (1938 and 1975) and six-match series (1970–71, 1974–75, 1978–79, 1981, 1985, 1989, 1993 and 1997). Australians have made 264 centuries in Ashes Tests, of which 23 have been scores over 200, while Englishmen have scored 212 centuries, of which 10 have been over 200. Australians have taken 10 wickets in a match on 41 occasions, Englishmen 38 times. Match venues. The series alternates between England (and Wales) and Australia, and each match of a series is held at a different ground. Australia. In Australia, the grounds currently used are The Gabba in Brisbane (first staged an England–Australia Test in the 1932–33 season), Adelaide Oval (1884–85), the Melbourne Cricket Ground (MCG) (1876–77), and the Sydney Cricket Ground (SCG) (1881–82). A single Test was held at the Brisbane Exhibition Ground in 1928–29. Traditionally, Melbourne hosts the Boxing Day Test and Sydney hosts the New Year's Day Test.
Additionally the WACA in Perth (1970–71) hosted its final Ashes Test in 2017–18 and was due to be replaced by Perth Stadium for the 2021–22 series. However, Western Australian border restrictions and quarantine requirements during the COVID-19 pandemic led to a change in venue for the final Ashes Test to Bellerive Oval in Hobart. This was the first Ashes Test match to be held in Tasmania. Cricket Australia proposed that the 2010–11 series consist of six Tests, with the additional game to be played at Bellerive Oval in Hobart. The England and Wales Cricket Board declined and the series was played over five Tests. England. In England and Wales, the grounds currently used are: Old Trafford in Manchester (1884), The Oval in Kennington, South London (1884); Lord's in St John's Wood, North London (1884); Headingley in Leeds (1899) and Edgbaston in Birmingham (1902). Additionally Sophia Gardens in Cardiff, Wales (2009); the Riverside Ground in Chester-le-Street, County Durham (2013) and Trent Bridge at West Bridgford (1899), have been used and one Test was also held at Bramall Lane in Sheffield in 1902. Traditionally the final Test of the series is played at the Oval.
Sophia Gardens and the Riverside were excluded as Test grounds between the years of 2020 and 2031 and therefore will not host an Ashes Test until at least 2035. The ECB announced the 2027 and 2031 Ashes series venues will be held at Lord's (2027 and 2031), The Oval (2027 and 2031), Edgbaston (2027), Trent Bridge (2027 and 2031), The Rose Bowl (2027), Old Trafford (2031) and Headingley (2031). Cultural references. The popularity and reputation of the cricket series has led to other sports and games using the name "Ashes" for contests between England/Great Britain and Australia. The best-known and longest-running of these events is the rugby league Ashes competition between Great Britain now England and Australia national rugby league teams. Use of the name "Ashes" was suggested by the Australian team when rugby league matches between the two countries commenced in 1908. Other examples included the television game shows "Gladiators" and "Sale of the Century", both of which broadcast special editions containing contestants from the Australian and English versions of the shows competing against each other.
The term was further genericised in Australia in the first half of the twentieth century, and was used to describe the most prominent rivalry or competition within a sport even if outside the context of Australia vs England. The Australian rules football interstate carnival, and the small silver casket which served as its trophy, were symbolically known as "the Ashes" of Australian football, and was spoken of as such until at least the 1940s. The soccer rivalry between Australia and New Zealand was described as "the soccer ashes of Australasia" until as late as the 1950s; ashes from cigars smoked by the two countries' captains were put into a casket in 1923 to make the trophy literal. The interstate rugby league rivalry between Queensland and New South Wales was known for a time as Australia's rugby league ashes, and bowls competitions between the two states also regularly used the term. Even some local rivalries, such as southern Western Australia's annual Great Southern Football Carnival, were locally described as "the ashes". This genericised usage is no longer common, and "the Ashes" would today be assumed only to apply to a contest between Australia and England.
The Ashes featured in the film "The Final Test", released in 1953, based on a television play by Terence Rattigan. It stars Jack Warner as an England cricketer playing the last Test of his career, which is the last of an Ashes series; the film includes cameo appearances of English captain Len Hutton and other players who were part of England's 1953 triumph. Douglas Adams's 1982 science fiction comedy novel "Life, the Universe and Everything" – the third part of "The Hitchhiker's Guide to the Galaxy" series – features the urn containing the Ashes as a significant element of its plot. The urn is stolen by alien robots, as the burnt stump inside is part of a key needed to unlock the "Wikkit Gate" and release an imprisoned world called Krikkit. "Bodyline", a fictionalised television miniseries based on the "Bodyline" Ashes series of 1932–33, was screened in Australia in 1984. The cast included Gary Sweet as Donald Bradman and Hugo Weaving as England captain Douglas Jardine. In the 1938 film "The Lady Vanishes", Charters and Caldicott, played by Basil Radford and Naunton Wayne are two cricket fans who are desperate to get home from Europe in order to see the last day's play in the Third Test at Manchester. It is not until they see a newsboy's poster near the end of the film that they discover that the match had been abandoned, due to floods.
Analysis Analysis (: analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (384–322 BC), though "analysis" as a formal concept is a relatively recent development. The word comes from the Ancient Greek ("analysis", "a breaking-up" or "an untying" from "ana-" "up, throughout" and "lysis" "a loosening"). From it also comes the word's plural, "analyses". As a formal concept, the method has variously been ascribed to René Descartes ("Discourse on the Method"), and Galileo Galilei. It has also been ascribed to Isaac Newton, in the form of a practical method of physical discovery (which he did not name). The converse of analysis is synthesis: putting the pieces back together again in a new or different whole. Science and technology. Chemistry. The field of chemistry uses analysis in three ways: to identify the components of a particular chemical compound (qualitative analysis), to identify the proportions of components in a mixture (quantitative analysis), and to break down chemical processes and examine chemical reactions between elements of matter. For an example of its use, analysis of the concentration of elements is important in managing a nuclear reactor, so nuclear scientists will analyze neutron activation to develop discrete measurements within vast samples. A matrix can have a considerable effect on the way a chemical analysis is conducted and the quality of its results. Analysis can be done manually or with a device.
Types of Analysis. A) Qualitative Analysis: It is concerned with which components are in a given sample or compound. Example: Precipitation reaction B) Quantitative Analysis: It is to determine the quantity of individual component present in a given sample or compound. Example: To find concentration by uv-spectrophotometer. Isotopes. Chemists can use isotope analysis to assist analysts with issues in anthropology, archeology, food chemistry, forensics, geology, and a host of other questions of physical science. Analysts can discern the origins of natural and man-made isotopes in the study of environmental radioactivity. Engineering. Analysts in the field of engineering look at requirements, structures, mechanisms, systems and dimensions. Electrical engineers analyse systems in electronics. Life cycles and system failures are broken down and studied by engineers. It is also looking at different factors incorporated within the design. Mathematics. Modern mathematical analysis is the study of infinite processes. It is the branch of mathematics that includes calculus. It can be applied in the study of classical concepts of mathematics, such as real numbers, complex variables, trigonometric functions, and algorithms, or of non-classical concepts like constructivism, harmonics, infinity, and vectors.
Florian Cajori explains in (1893) the difference between modern and ancient mathematical analysis, as distinct from logical analysis, as follows: The terms "synthesis" and "analysis" are used in mathematics in a more special sense than in logic. In ancient mathematics they had a different meaning from what they now have. The oldest definition of mathematical analysis as opposed to synthesis is that given in [appended to] Euclid, XIII. 5, which in all probability was framed by Eudoxus: "Analysis is the obtaining of the thing sought by assuming it and so reasoning up to an admitted truth; synthesis is the obtaining of the thing sought by reasoning up to the inference and proof of it." The analytic method is not conclusive, unless all operations involved in it are known to be reversible. To remove all doubt, the Greeks, as a rule, added to the analytic process a synthetic one, consisting of a reversion of all operations occurring in the analysis. Thus the aim of analysis was to aid in the discovery of synthetic proofs or solutions.
James Gow uses a similar argument as Cajori, with the following clarification, in his "A Short History of Greek Mathematics" (1884): The synthetic proof proceeds by shewing that the proposed new truth involves certain admitted truths. An analytic proof begins by an assumption, upon which a synthetic reasoning is founded. The Greeks distinguished "theoretic" from "problematic" analysis. A theoretic analysis is of the following kind. To "prove" that A is B, "assume" first that A is B. If so, then, since B is C and C is D and D is E, therefore A is E. If this be known a falsity, A is not B. But if this be a known truth and all the intermediate propositions be convertible, then the reverse process, A is E, E is D, D is C, C is B, therefore A is B, constitutes a synthetic proof of the original theorem. Problematic analysis is applied in all cases where it is proposed to construct a figure which is assumed to satisfy a given condition. The problem is then converted into some theorem which is involved in the condition and which is proved synthetically, and the steps of this synthetic proof taken backwards are a synthetic solution of the problem.
Statistics. In statistics, the term "analysis" may refer to any method used for data analysis. Among the many such methods, some are: Government. Intelligence. The field of intelligence employs analysts to break down and understand a wide array of questions. Intelligence agencies may use heuristics, inductive and deductive reasoning, social network analysis, dynamic network analysis, link analysis, and brainstorming to sort through problems they face. Military intelligence may explore issues through the use of game theory, Red Teaming, and wargaming. Signals intelligence applies cryptanalysis and frequency analysis to break codes and ciphers. Business intelligence applies theories of competitive intelligence analysis and competitor analysis to resolve questions in the marketplace. Law enforcement intelligence applies a number of theories in crime analysis. Humanities and social sciences. Linguistics. Linguistics explores individual languages and language in general. It breaks language down and analyses its component parts: theory, sounds and their meaning, utterance usage, word origins, the history of words, the meaning of words and word combinations, sentence construction, basic construction beyond the sentence level, stylistics, and conversation. It examines the above using statistics and modeling, and semantics. It analyses language in context of anthropology, biology, evolution, geography, history, neurology, psychology, and sociology. It also takes the applied approach, looking at individual language development and clinical issues.
Literature. Literary criticism is the analysis of literature. The focus can be as diverse as the analysis of Homer or Freud. While not all literary-critical methods are primarily analytical in nature, the main approach to the teaching of literature in the west since the mid-twentieth century, literary formal analysis or close reading, is. This method, rooted in the academic movement labelled The New Criticism, approaches texts – chiefly short poems such as sonnets, which by virtue of their small size and significant complexity lend themselves well to this type of analysis – as units of discourse that can be understood in themselves, without reference to biographical or historical frameworks. This method of analysis breaks up the text linguistically in a study of prosody (the formal analysis of meter) and phonic effects such as alliteration and rhyme, and cognitively in examination of the interplay of syntactic structures, figurative language, and other elements of the poem that work to produce its larger effects.
Abner Doubleday Abner Doubleday (June 26, 1819 – January 26, 1893) was a career United States Army officer and Union major general in the American Civil War. He fired the first shot in defense of Fort Sumter, the opening battle of the war, and had a pivotal role in the early fighting at the Battle of Gettysburg. Gettysburg was his finest hour, but his relief by Maj. Gen. George G. Meade caused lasting enmity between the two men. In San Francisco, after the war, he obtained a patent on the cable car railway that still runs there. In his final years in New Jersey, he was a prominent member and later president of the Theosophical Society. In 1908, 15 years after his death, the Mills Commission declared that Doubleday had invented the game of baseball, although Doubleday never made such a claim. This claim has been thoroughly debunked by baseball historians. Early years. Doubleday, the son of Ulysses F. Doubleday and Hester Donnelly, was born in Ballston Spa, New York, in a small house on the corner of Washington and Fenwick streets. As a child, Abner was very short. The family all slept in the attic loft of the one-room house. His paternal grandfather, also named Abner, had fought in the American Revolutionary War. His maternal grandfather Thomas Donnelly had joined the army at 14 and was a mounted messenger for George Washington. His great-grandfather Peter Donnelly was a Minuteman. His father, Ulysses F., fought in the War of 1812, published newspapers and books, and represented Auburn, New York, for four years in the United States Congress. Abner spent his childhood in Auburn and later was sent to Cooperstown to live with his uncle and attend a private preparatory high school. He practiced as a surveyor and civil engineer for two years before entering the United States Military Academy in 1838. He graduated in 1842, 24th in a class of 56 cadets, and was commissioned a brevet second lieutenant in the 3rd U.S. Artillery. In 1852, he married Mary Hewitt of Baltimore, the daughter of a local lawyer.
Early commands and Fort Sumter. Doubleday initially served in coastal garrisons and then in the Mexican–American War from 1846 to 1848 and the Seminole Wars from 1856 to 1858. In 1858, he was transferred to Fort Moultrie in Charleston Harbor serving under Colonel John L. Gardner. By the start of the Civil War, he was a captain and second in command in the garrison at Fort Sumter, under Major Robert Anderson. He aimed the cannon that fired the first return shot in answer to the Confederate bombardment on April 12, 1861. He subsequently referred to himself as the "hero of Sumter" for this role. Of note, although Doubleday did not invent baseball, by sheer coincidence the Fort Sumter Garrison Flag (or Storm Flag) has the star pattern arranged in a diamond shape, which by that time in history, was the shape of the baseball infield. Brigade and division command in Virginia.
Doubleday again led the division, now assigned to the I Corps of the Army of the Potomac, after South Mountain, where Hatch was wounded again. At Antietam, he led his men into the deadly fighting in the Cornfield and the West Woods, and one colonel described him as a "gallant officer ... remarkably cool and at the very front of battle." He was wounded when an artillery shell exploded near his horse, throwing him to the ground in a violent fall. He received a brevet promotion to lieutenant colonel in the regular army for his actions at Antietam and was promoted in March 1863 to major general of volunteers, to rank from November 29, 1862. At Fredericksburg in December 1862, his division mostly sat idle. During the winter, the I Corps was reorganized and Doubleday assumed command of the 3rd Division. At Chancellorsville in May 1863, the division was kept in reserve. Gettysburg.
On July 2, 1863, Army of the Potomac commander Maj. Gen. George G. Meade replaced Doubleday with Major General John Newton, a more junior officer from another corps. The ostensible reason was a false report by XI Corps commander Major General Oliver O. Howard that Doubleday's corps broke first, causing the entire Union line to collapse, but Meade also had a long history of disdain for Doubleday's combat effectiveness, dating back to South Mountain. Doubleday was humiliated by this snub and held a lasting grudge against Meade, but he returned to division command and fought well for the remainder of the battle. He was wounded in the neck on the second day of Gettysburg and received a brevet promotion to colonel in the regular army for his service. He formally requested reinstatement as I Corps commander, but Meade refused, and Doubleday left Gettysburg on July 7 for Washington. Doubleday's staff nicknamed him "Forty-Eight Hours" as a compliment to recognize his tendency to avoid reckless or impulsive actions and his thoughtfulness and deliberateness in considering circumstances and possible responses. In recent years, biographers have turned the nickname into an insult, incorrectly claiming "Forty-Eight Hours" was coined to highlight Doubleday's supposed incompetence and slowness to act.
Washington. Doubleday assumed administrative duties in the defenses of Washington, D.C., where he was in charge of courts martial, which gave him legal experience that he used after the war. His only return to combat was directing a portion of the defenses against the attack by Confederate Lieutenant General Jubal A. Early in the Valley Campaigns of 1864. Also while in Washington, Doubleday testified against George Meade at the United States Congress Joint Committee on the Conduct of the War, criticizing him harshly over his conduct of the Battle of Gettysburg. While in Washington, Doubleday remained a loyal Republican and staunch supporter of President Abraham Lincoln. Doubleday rode with Lincoln on the train to Gettysburg for the Gettysburg Address and Col. and Mrs. Doubleday attended events with Mr. and Mrs. Lincoln in Washington. Postbellum career. After the Civil War, Doubleday mustered out of the volunteer service on August 24, 1865, reverted to the rank of lieutenant colonel, and became the colonel of the 35th U.S. Infantry in September 1867. He was stationed in San Francisco from 1869 through 1871 and he took out a patent for the cable car railway that still runs there, receiving a charter for its operation, but signing away his rights when he was reassigned. In 1871, he commanded the 24th U.S. Infantry, an all African-American regiment with headquarters at Fort McKavett, Texas. He retired in 1873.
In the 1870s, he was listed in the New York business directory as a lawyer. Doubleday spent much of his time writing. He published two important works on the Civil War: "Reminiscences of Forts Sumter and Moultrie" (1876), and "Chancellorsville and Gettysburg" (1882), the latter being a volume of the series "Campaigns of the Civil War". Theosophy. In the summer of 1878, Doubleday lived in Mendham Township, New Jersey, and became a prominent member of the Theosophical Society. When two of the founders of that society, Helena Blavatsky and Henry Steel Olcott, moved to India at the end of that year, he was constituted as the president of the American body. Death. Doubleday died of heart disease in Mendham Township on January 26, 1893. Doubleday's body was laid in state in New York's City Hall and then was taken to Washington by train from Mendham, and was buried in Arlington National Cemetery in Arlington County, Virginia. He was survived by his wife. Baseball. Although Doubleday achieved minor fame as a competent combat general with experience in many important Civil War battles, he is more widely known as the supposed inventor of the game of baseball, in Elihu Phinney's cow pasture in Cooperstown, New York, in 1839.
The Mills Commission, chaired by Abraham G. Mills, the fourth president of the National League, was appointed in 1905 to determine the origin of baseball. The committee's final report, on December 30, 1907, stated, in part, that "the first scheme for playing baseball, according to the best evidence obtainable to date, was devised by Abner Doubleday at Cooperstown, New York, in 1839." It concluded by saying, "in the years to come, in the view of the hundreds of thousands of people who are devoted to baseball, and the millions who will be, Abner Doubleday's fame will rest evenly, if not quite as much, upon the fact that he was its inventor ... as upon his brilliant and distinguished career as an officer in the Federal Army."
Despite the lack of solid evidence linking Doubleday to the origins of baseball, Cooperstown, New York, became the new home of what is today the National Baseball Hall of Fame and Museum in 1937. There may have been some relationship to baseball as a national sport and Abner Doubleday. While the modern rules of baseball were formulated in New York during the 1840s, it was the scattering of New Yorkers exposed to these rules throughout the country, that spread not only baseball, but also the "New York Rules", thereby harmonizing the rules, and being a catalyst for its growth. Doubleday was a high-ranking officer, whose duties included seeing to provisions for the US Army fighting throughout the south and border states. For the morale of the men, he is said to have provisioned balls and bats for the men. Namesakes and honors. Doubleday's men, admirers, and the state of New York erected a monument to him at Gettysburg. There is a obelisk monument at Arlington National Cemetery where he is buried. Doubleday Field is a 9,791-seat baseball stadium named for Abner Doubleday, located in Cooperstown, New York, near the Baseball Hall of Fame. It hosted the annual Hall of Fame Game, an exhibition game between two major league teams that was played from 1940 until 2008. It has hosted the Hall of Fame Classic since 2009.
The Auburn Doubledays are a collegiate summer baseball team based in Doubleday's hometown of Auburn, New York. Doubleday Field at the United States Military Academy at West Point, New York, where the Army Black Knights play at Johnson Stadium, is named in Doubleday's honor. The Abner Doubleday Little League and Babe Ruth Fields in Ballston Spa, New York, the town of his birth. The house of his birth still stands in the middle of town and there is a monument to him on Front Street. A sign at the Doubleday Hill Monument, erected in Williamsport, Maryland, to commemorate Doubleday's occupation of a hill there during the Civil War, claims he invented the game in 1835. Mendham Borough and Mendham Township, New Jersey has held a municipal holiday known as "Abner Doubleday Day" for numerous years in the General's honor and commissioned a plaque near the site of his home in the borough in 1998, even though the borough was known as Mendham Township back then. In 2004, the Abner Doubleday Society erected a monument to Doubleday in Iron Spring Park, Ballston Spa, near his birthplace.
America's National Game America's National Game is a book by Albert Spalding, published in 1911, that details the early history of the sport of baseball. It is one of the defining books in the early formative years of modern baseball. Much of the story is told first-hand; since the 1850s, Spalding had been involved in the game, first as a pitcher and later a manager and club owner. Later he branched out to become a leading manufacturer of sporting goods. In addition to his personal recollections, he had access to the records of Henry Chadwick, the game's first statistician and archivist. Much of his early history of the game is considered to be reliable. Spalding was, however, said to aggrandize his role in the major moments in baseball's history. Early editions of the book include quality full-page photo-plates of important players.
Amplitude modulation Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation. AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden's radiotelephone experiments in 1900. This original form of AM is sometimes called double-sideband amplitude modulation (DSBAM), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands and possibly the carrier signal, which improves the ratio of message power to total transmission power, reduces power handling requirements of line repeaters, and permits better bandwidth utilization of the transmission medium.
AM remains in use in many forms of communication in addition to AM broadcasting: shortwave radio, amateur radio, two-way radios, VHF aircraft radio, citizens band radio, and in computer modems in the form of quadrature amplitude modulation (QAM). Foundation. In electronics, telecommunications and mechanics, modulation means varying some aspect of a continuous wave carrier signal with an information-bearing modulation waveform, such as an audio signal which represents sound, or a video signal which represents images. In this sense, the carrier wave, which has a much higher frequency than the message signal, "carries" the information. At the receiving station, the message signal is extracted from the modulated carrier by demodulation. In general form, a modulation process of a sinusoidal carrier wave may be described by the following equation: "A(t)" represents the time-varying amplitude of the sinusoidal carrier wave and the cosine-term is the carrier at its angular frequency formula_2, and the instantaneous phase deviation formula_3. This description directly provides the two major groups of modulation, amplitude modulation and angle modulation. In angle modulation, the term "A"("t") is constant and the second term of the equation has a functional relationship to the modulating message signal. Angle modulation provides two methods of modulation, frequency modulation and phase modulation.
In amplitude modulation, the angle term is held constant and the first term, "A"("t"), of the equation has a functional relationship to the modulating message signal. The modulating message signal may be analog in nature, or it may be a digital signal, in which case the technique is generally called amplitude-shift keying. For example, in AM radio communication, a continuous wave radio-frequency signal has its amplitude modulated by an audio waveform before transmission. The message signal determines the "envelope" of the transmitted waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency and two adjacent sidebands. Each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called "double-sideband amplitude modulation" (DSBAM). A disadvantage of all amplitude modulation techniques, not only standard AM, is that the receiver amplifies and detects noise and electromagnetic interference in equal proportion to the signal. Increasing the received signal-to-noise ratio, say, by a factor of 10 (a 10 decibel improvement), thus would require increasing the transmitter power by a factor of 10. This is in contrast to frequency modulation (FM) and digital radio where the effect of such noise following demodulation is strongly reduced so long as the received signal is well above the threshold for reception. For this reason AM broadcast is not favored for music and high fidelity broadcasting, but rather for voice communications and broadcasts (sports, news, talk radio etc.).
AM is also inefficient in power usage; at least two-thirds of the power is concentrated in the carrier signal. The carrier signal contains none of the original information being transmitted (voice, video, data, etc.). However its presence provides a simple means of demodulation using envelope detection, providing a frequency and phase reference to extract the modulation from the sidebands. In some modulation systems based on AM, a lower transmitter power is required through partial or total elimination of the carrier component, however receivers for these signals are more complex because they must provide a precise carrier frequency reference signal (usually as shifted to the intermediate frequency) from a greatly reduced "pilot" carrier (in reduced-carrier transmission or DSB-RC) to use in the demodulation process. Even with the carrier eliminated in double-sideband suppressed-carrier transmission, carrier regeneration is possible using a Costas phase-locked loop. This does not work for single-sideband suppressed-carrier transmission (SSB-SC), leading to the characteristic "Donald Duck" sound from such receivers when slightly detuned. Single-sideband AM is nevertheless used widely in amateur radio and other voice communications because it has power and bandwidth efficiency (cutting the RF bandwidth in half compared to standard AM). On the other hand, in medium wave and short wave broadcasting, standard AM with the full carrier allows for reception using inexpensive receivers. The broadcaster absorbs the extra power cost to greatly increase potential audience.
Shift keying. A simple form of digital amplitude modulation which can be used for transmitting binary data is on–off keying, the simplest form of amplitude-shift keying, in which ones and zeros are represented by the presence or absence of a carrier. On–off keying is likewise used by radio amateurs to transmit Morse code where it is known as continuous wave (CW) operation, even though the transmission is not strictly "continuous". A more complex form of AM, quadrature amplitude modulation is now more commonly used with digital data, while making more efficient use of the available bandwidth. Analog telephony. A simple form of amplitude modulation is the transmission of speech signals from a traditional analog telephone set using a common battery local loop. The direct current provided by the central office battery is a carrier with a frequency of 0 Hz. It is modulated by a microphone ("transmitter") in the telephone set according to the acoustic signal from the speaker. The result is a varying amplitude direct current, whose AC-component is the speech signal extracted at the central office for transmission to another subscriber.
Amplitude reference. An additional function provided by the carrier in standard AM, but which is lost in either single or double-sideband suppressed-carrier transmission, is that it provides an amplitude reference. In the receiver, the automatic gain control (AGC) responds to the carrier so that the reproduced audio level stays in a fixed proportion to the original modulation. On the other hand, with suppressed-carrier transmissions there is "no" transmitted power during pauses in the modulation, so the AGC must respond to peaks of the transmitted power during peaks in the modulation. This typically involves a so-called "fast attack, slow decay" circuit which holds the AGC level for a second or more following such peaks, in between syllables or short pauses in the program. This is very acceptable for communications radios, where compression of the audio aids intelligibility. However, it is absolutely undesired for music or normal broadcast programming, where a faithful reproduction of the original program, including its varying modulation levels, is expected.
ITU type designations. In 1982, the International Telecommunication Union (ITU) designated the types of amplitude modulation: History. Amplitude modulation was used in experiments of multiplex telegraph and telephone transmission in the late 1800s. However, the practical development of this technology is identified with the period between 1900 and 1920 of radiotelephone transmission, that is, the effort to send audio signals by radio waves. The first radio transmitters, called spark gap transmitters, transmitted information by wireless telegraphy, using pulses of the carrier wave to spell out text messages in Morse code. They could not transmit audio because the carrier consisted of strings of damped waves, pulses of radio waves that declined to zero, and sounded like a buzz in receivers. In effect they were already amplitude modulated. Continuous waves. The first AM transmission was made by Canadian-born American researcher Reginald Fessenden on December 23, 1900 using a spark gap transmitter with a specially designed high frequency 10 kHz interrupter, over a distance of at Cobb Island, Maryland, US. His first transmitted words were, "Hello. One, two, three, four. Is it snowing where you are, Mr. Thiessen?". Though his words were "perfectly intelligible", the spark created a loud and unpleasant noise.
Fessenden was a significant figure in the development of AM radio. He was one of the first researchers to realize, from experiments like the above, that the existing technology for producing radio waves, the spark transmitter, was not usable for amplitude modulation, and that a new kind of transmitter, one that produced sinusoidal "continuous waves", was needed. This was a radical idea at the time, because experts believed the impulsive spark was necessary to produce radio frequency waves, and Fessenden was ridiculed. He invented and helped develop one of the first continuous wave transmitters – the Alexanderson alternator, with which he made what is considered the first AM public entertainment broadcast on Christmas Eve, 1906. He also discovered the principle on which AM is based, heterodyning, and invented one of the first detectors able to rectify and receive AM, the electrolytic detector or "liquid baretter", in 1902. Other radio detectors invented for wireless telegraphy, such as the Fleming valve (1904) and the crystal detector (1906) also proved able to rectify AM signals, so the technological hurdle was generating AM waves; receiving them was not a problem.
Early technologies. Early experiments in AM radio transmission, conducted by Fessenden, Valdemar Poulsen, Ernst Ruhmer, Quirino Majorana, Charles Herrold, and Lee de Forest, were hampered by the lack of a technology for amplification. The first practical continuous wave AM transmitters were based on either the huge, expensive Alexanderson alternator, developed 1906–1910, or versions of the Poulsen arc transmitter (arc converter), invented in 1903. The modifications necessary to transmit AM were clumsy and resulted in very low quality audio. Modulation was usually accomplished by a carbon microphone inserted directly in the antenna or ground wire; its varying resistance varied the current to the antenna. The limited power handling ability of the microphone severely limited the power of the first radiotelephones; many of the microphones were water-cooled. Vacuum tubes. The 1912 discovery of the amplifying ability of the Audion tube, invented in 1906 by Lee de Forest, solved these problems. The vacuum tube feedback oscillator, invented in 1912 by Edwin Armstrong and Alexander Meissner, was a cheap source of continuous waves and could be easily modulated to make an AM transmitter. Modulation did not have to be done at the output but could be applied to the signal before the final amplifier tube, so the microphone or other audio source didn't have to modulate a high-power radio signal. Wartime research greatly advanced the art of AM modulation, and after the war the availability of cheap tubes sparked a great increase in the number of radio stations experimenting with AM transmission of news or music. The vacuum tube was responsible for the rise of AM broadcasting around 1920, the first electronic mass communication medium. Amplitude modulation was virtually the only type used for radio broadcasting until FM broadcasting began after World War II.
At the same time as AM radio began, telephone companies such as AT&T were developing the other large application for AM: sending multiple telephone calls through a single wire by modulating them on separate carrier frequencies, called "frequency division multiplexing". Single-sideband. In 1915, John Renshaw Carson formulated the first mathematical description of amplitude modulation, showing that a signal and carrier frequency combined in a nonlinear device creates a sideband on both sides of the carrier frequency. Passing the modulated signal through another nonlinear device can extract the original baseband signal. His analysis also showed that only one sideband was necessary to transmit the audio signal, and Carson patented single-sideband modulation (SSB) on 1 December 1915. This advanced variant of amplitude modulation was adopted by AT&T for longwave transatlantic telephone service beginning 7 January 1927. After WW-II, it was developed for military aircraft communication. Analysis. The carrier wave (sine wave) of frequency "fc" and amplitude "A" is expressed by
The message signal, such as an audio signal that is used for modulating the carrier, is "m"("t"), and has a frequency "fm", much lower than "fc": where "m" is the amplitude sensitivity, "M" is the amplitude of modulation. If "m" < 1, "(1 + m(t)/A)" is always positive for undermodulation. If "m" > 1 then overmodulation occurs and reconstruction of message signal from the transmitted signal would lead in loss of original signal. Amplitude modulation results when the carrier "c(t)" is multiplied by the positive quantity "(1 + m(t)/A)": In this simple case "m" is identical to the modulation index, discussed below. With "m" = 0.5 the amplitude modulated signal "y"("t") thus corresponds to the top graph (labelled "50% Modulation") in figure 4. Using prosthaphaeresis identities, "y"("t") can be shown to be the sum of three sine waves: Therefore, the modulated signal has three components: the carrier wave "c(t)" which is unchanged in frequency, and two sidebands with frequencies slightly above and below the carrier frequency "fc".
Spectrum. A useful modulation signal "m(t)" is usually more complex than a single sine wave, as treated above. However, by the principle of Fourier decomposition, "m(t)" can be expressed as the sum of a set of sine waves of various frequencies, amplitudes, and phases. Carrying out the multiplication of "1 + m(t)" with "c(t)" as above, the result consists of a sum of sine waves. Again, the carrier "c(t)" is present unchanged, but each frequency component of "m" at "fi" has two sidebands at frequencies "fc + fi" and "fc – fi". The collection of the former frequencies above the carrier frequency is known as the upper sideband, and those below constitute the lower sideband. The modulation "m(t)" may be considered to consist of an equal mix of positive and negative frequency components, as shown in the top of figure 2. One can view the sidebands as that modulation "m(t)" having simply been shifted in frequency by "fc" as depicted at the bottom right of figure 2. The short-term spectrum of modulation, changing as it would for a human voice for instance, the frequency content (horizontal axis) may be plotted as a function of time (vertical axis), as in figure 3. It can again be seen that as the modulation frequency content varies, an upper sideband is generated according to those frequencies shifted "above" the carrier frequency, and the same content mirror-imaged in the lower sideband below the carrier frequency. At all times, the carrier itself remains constant, and of greater power than the total sideband power.
Power and spectrum efficiency. The RF bandwidth of an AM transmission (refer to figure 2, but only considering positive frequencies) is twice the bandwidth of the modulating (or "baseband") signal, since the upper and lower sidebands around the carrier frequency each have a bandwidth as wide as the highest modulating frequency. Although the bandwidth of an AM signal is narrower than one using frequency modulation (FM), it is twice as wide as single-sideband techniques; it thus may be viewed as spectrally inefficient. Within a frequency band, only half as many transmissions (or "channels") can thus be accommodated. For this reason analog television employs a variant of single-sideband (known as vestigial sideband, somewhat of a compromise in terms of bandwidth) in order to reduce the required channel spacing.
A technique used widely in broadcast AM transmitters is an application of the Hapburg carrier, first proposed in the 1930s but impractical with the technology then available. During periods of low modulation the carrier power would be reduced and would return to full power during periods of high modulation levels. This has the effect of reducing the overall power demand of the transmitter and is most effective on speech type programmes. Various trade names are used for its implementation by the transmitter manufacturers from the late 80's onwards. Modulation index. The AM modulation index is a measure based on the ratio of the modulation excursions of the RF signal to the level of the unmodulated carrier. It is thus defined as: where formula_9 and formula_10 are the modulation amplitude and carrier amplitude, respectively; the modulation amplitude is the peak (positive or negative) change in the RF amplitude from its unmodulated value. Modulation index is normally expressed as a percentage, and may be displayed on a meter connected to an AM transmitter.
So if formula_11, carrier amplitude varies by 50% above (and below) its unmodulated level, as is shown in the first waveform, below. For formula_12, it varies by 100% as shown in the illustration below it. With 100% modulation the wave amplitude sometimes reaches zero, and this represents full modulation using standard AM and is often a target (in order to obtain the highest possible signal-to-noise ratio) but mustn't be exceeded. Increasing the modulating signal beyond that point, known as overmodulation, causes a standard AM modulator (see below) to fail, as the negative excursions of the wave envelope cannot become less than zero, resulting in distortion ("clipping") of the received modulation. Transmitters typically incorporate a limiter circuit to avoid overmodulation, and/or a compressor circuit (especially for voice communications) in order to still approach 100% modulation for maximum intelligibility above the noise. Such circuits are sometimes referred to as a vogad.
Modulation methods. Modulation circuit designs may be classified as low- or high-level (depending on whether they modulate in a low-power domain—followed by amplification for transmission—or in the high-power domain of the transmitted signal). Low-level generation. In modern radio systems, modulated signals are generated via digital signal processing (DSP). With DSP many types of AM are possible with software control (including DSB with carrier, SSB suppressed-carrier and independent sideband, or ISB). Calculated digital samples are converted to voltages with a digital-to-analog converter, typically at a frequency less than the desired RF-output frequency. The analog signal must then be shifted in frequency and linearly amplified to the desired frequency and power level (linear amplification must be used to prevent modulation distortion). This low-level method for AM is used in many Amateur Radio transceivers. AM may also be generated at a low level, using analog methods described in the next section. High-level generation.
High-power AM transmitters (such as those used for AM broadcasting) are based on high-efficiency class-D and class-E power amplifier stages, modulated by varying the supply voltage. Older designs (for broadcast and amateur radio) also generate AM by controlling the gain of the transmitter's final amplifier (generally class-C, for efficiency). The following types are for vacuum tube transmitters (but similar options are available with transistors): Demodulation methods. The simplest form of AM demodulator consists of a diode which is configured to act as envelope detector. Another type of demodulator, the product detector, can provide better-quality demodulation with additional circuit complexity.
Augustin-Jean Fresnel Augustin-Jean Fresnel (10 May 1788 – 14 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light, excluding any remnant of Newton's corpuscular theory, from the late 1830s until the end of the 19th century. He is perhaps better known for inventing the catadioptric (reflective/refractive) Fresnel lens and for pioneering the use of "stepped" lenses to extend the visibility of lighthouses, saving countless lives at sea. The simpler dioptric (purely refractive) stepped lens, first proposed by Count Buffon and independently reinvented by Fresnel, is used in screen magnifiers and in condenser lenses for overhead projectors. By expressing Huygens's principle of secondary waves and Young's principle of interference in quantitative terms, and supposing that simple colors consist of sinusoidal waves, Fresnel gave the first satisfactory explanation of diffraction by straight edges, including the first satisfactory wave-based explanation of rectilinear propagation. Part of his argument was a proof that the addition of sinusoidal functions of the same frequency but different phases is analogous to the addition of forces with different directions. By further supposing that light waves are purely transverse, Fresnel explained the nature of polarization, the mechanism of chromatic polarization, and the transmission and reflection coefficients at the interface between two transparent isotropic media. Then, by generalizing the direction-speed-polarization relation for calcite, he accounted for the directions and polarizations of the refracted rays in doubly-refractive crystals of the "biaxial" class (those for which Huygens's secondary wavefronts are not axisymmetric). The period between the first publication of his pure-transverse-wave hypothesis, and the submission of his first correct solution to the biaxial problem, was less than a year.
Later, he coined the terms "linear polarization", "circular polarization", and "elliptical polarization", explained how optical rotation could be understood as a difference in propagation speeds for the two directions of circular polarization, and (by allowing the reflection coefficient to be complex) accounted for the change in polarization due to total internal reflection, as exploited in the Fresnel rhomb. Defenders of the established corpuscular theory could not match his quantitative explanations of so many phenomena on so few assumptions. Fresnel had a lifelong battle with tuberculosis, to which he succumbed at the age of 39. Although he did not become a public celebrity in his lifetime, he lived just long enough to receive due recognition from his peers, including (on his deathbed) the Rumford Medal of the Royal Society of London, and his name is ubiquitous in the modern terminology of optics and waves. After the wave theory of light was subsumed by Maxwell's electromagnetic theory in the 1860s, some attention was diverted from the magnitude of Fresnel's contribution. In the period between Fresnel's unification of physical optics and Maxwell's wider unification, a contemporary authority, Humphrey Lloyd, described Fresnel's transverse-wave theory as "the noblest fabric which has ever adorned the domain of physical science, Newton's system of the universe alone excepted."
Early life. Family. Augustin-Jean Fresnel (also called Augustin Jean or simply Augustin), born in Broglie, Normandy, on 10 May 1788, was the second of four sons of the architect Jacques Fresnel and his wife Augustine, "née" Mérimée. The family moved twice—in 1789/90 to Cherbourg, and in 1794 to Jacques's home town of Mathieu, where Augustine would spend 25 years as a widow, outliving two of her sons. The first son, Louis, was admitted to the École Polytechnique, became a lieutenant in the artillery, and was killed in action at Jaca, Spain. The third, Léonor, followed Augustin into civil engineering, succeeded him as secretary of the Lighthouse Commission, and helped to edit his collected works. The fourth, Fulgence Fresnel, became a linguist, diplomat, and orientalist, and occasionally assisted Augustin with negotiations. Fulgence died in Bagdad in 1855 having led a mission to explore Babylon. Madame Fresnel's younger brother, Jean François "Léonor" Mérimée, father of the writer Prosper Mérimée, was a painter who turned his attention to the chemistry of painting. He became the Permanent Secretary of the École des Beaux-Arts and (until 1814) a professor at the École Polytechnique, and was the initial point of contact between Augustin and the leading optical physicists of the day .
Education. The Fresnel brothers were initially home-schooled by their mother. The sickly Augustin was considered the slow one, not inclined to memorization; but the popular story that he hardly began to read until the age of eight is disputed. At the age of nine or ten he was undistinguished except for his ability to turn tree-branches into toy bows and guns that worked far too well, earning himself the title "l'homme de génie" (the man of genius) from his accomplices, and a united crackdown from their elders. In 1801, Augustin was sent to the "École Centrale" at Caen, as company for Louis. But Augustin lifted his performance: in late 1804 he was accepted into the École Polytechnique, being placed 17th in the entrance examination. As the detailed records of the École Polytechnique begin in 1808, we know little of Augustin's time there, except that he made few if any friends and—in spite of continuing poor health—excelled in drawing and geometry: in his first year he took a prize for his solution to a geometry problem posed by Adrien-Marie Legendre. Graduating in 1806, he then enrolled at the École Nationale des Ponts et Chaussées (National School of Bridges and Roads, also known as "ENPC" or "École des Ponts"), from which he graduated in 1809, entering the service of the Corps des Ponts et Chaussées as an "ingénieur ordinaire aspirant" (ordinary engineer in training). Directly or indirectly, he was to remain in the employment of the "Corps des Ponts" for the rest of his life.
Religious formation. Fresnel's parents were Roman Catholics of the Jansenist sect, characterized by an extreme Augustinian view of original sin. Religion took first place in the boys' home-schooling. In 1802, his mother said: Augustin remained a Jansenist. He regarded his intellectual talents as gifts from God, and considered it his duty to use them for the benefit of others. According to his fellow engineer Alphonse Duleau, who helped to nurse him through his final illness, Fresnel saw the study of nature as part of the study of the power and goodness of God. He placed virtue above science and genius. In his last days he prayed for "strength of soul," not against death alone, but against "the interruption of discoveries… of which he hoped to derive useful applications." Jansenism is considered heretical by the Roman Catholic Church, and Grattan-Guinness suggests this is why Fresnel never gained a permanent academic teaching post; his only teaching appointment was at the Athénée in the winter of 1819–20. The article on Fresnel in the "Catholic Encyclopedia" does not mention his Jansenism, but describes him as "a deeply religious man and remarkable for his keen sense of duty."
Engineering assignments. Fresnel was initially posted to the western département of Vendée. There, in 1811, he anticipated what became known as the Solvay process for producing soda ash, except that recycling of the ammonia was not considered. That difference may explain why leading chemists, who learned of his discovery through his uncle Léonor, eventually thought it uneconomic. About 1812, Fresnel was sent to Nyons, in the southern département of Drôme, to assist with the imperial highway that was to connect Spain and Italy. It is from Nyons that we have the first evidence of his interest in optics. On 15 May 1814, while work was slack due to Napoleon's defeat, Fresnel wrote a "P.S." to his brother Léonor, saying in part: As late as 28 December he was still waiting for information, but by 10 February 1815 he had received Biot's memoir. (The "Institut de France" had taken over the functions of the French "Académie des Sciences" and other "académies" in 1795. In 1816 the "Académie des Sciences" regained its name and autonomy, but remained part of the institute.)
In March 1815, perceiving Napoleon's return from Elba as "an attack on civilization", Fresnel departed without leave, hastened to Toulouse and offered his services to the royalist resistance, but soon found himself on the sick list. Returning to Nyons in defeat, he was threatened and had his windows broken. During the Hundred Days he was placed on suspension, which he was eventually allowed to spend at his mother's house in Mathieu. There he used his enforced leisure to begin his optical experiments. Contributions to physical optics. Historical context: From Newton to Biot. The appreciation of Fresnel's reconstruction of physical optics might be assisted by an overview of the fragmented state in which he found the subject. In this subsection, optical phenomena that were unexplained or whose explanations were disputed are named in bold type.
Huygens's theory neatly explained the law of ordinary reflection and the law of ordinary refraction ("Snell's law"), provided that the secondary waves traveled slower in denser media (those of higher refractive index). The corpuscular theory, with the hypothesis that the corpuscles were subject to forces acting perpendicular to surfaces, explained the same laws equally well, albeit with the implication that light traveled "faster" in denser media; that implication was wrong, but could not be directly disproven with the technology of Newton's time or even Fresnel's time . Similarly inconclusive was stellar aberration—that is, the apparent change in the position of a star due to the velocity of the earth across the line of sight (not to be confused with stellar parallax, which is due to the "displacement" of the earth across the line of sight). Identified by James Bradley in 1728, stellar aberration was widely taken as confirmation of the corpuscular theory. But it was equally compatible with the wave theory, as Euler noted in 1746—tacitly assuming that the aether (the supposed wave-bearing medium) near the earth was not disturbed by the motion of the earth.
The outstanding strength of Huygens's theory was his explanation of the birefringence (double refraction) of "Iceland crystal" (transparent calcite), on the assumption that the secondary waves are spherical for the ordinary refraction (which satisfies Snell's law) and spheroidal for the "extraordinary" refraction (which does not). In general, Huygens's common-tangent construction implies that rays are "paths of least time" between successive positions of the wavefront, in accordance with Fermat's principle. In the special case of isotropic media, the secondary wavefronts must be spherical, and Huygens's construction then implies that the rays are perpendicular to the wavefront; indeed, the law of "ordinary" refraction can be separately derived from that premise, as Ignace-Gaston Pardies did before Huygens.
Neither Newton nor Huygens satisfactorily explained diffraction—the blurring and fringing of shadows where, according to rectilinear propagation, they ought to be sharp. Newton, who called diffraction "inflexion", supposed that rays of light passing close to obstacles were bent ("inflected"); but his explanation was only qualitative. Huygens's common-tangent construction, without modifications, could not accommodate diffraction at all. Two such modifications were proposed by Young in the same 1801 Bakerian Lecture: first, that the secondary waves near the edge of an obstacle could diverge into the shadow, but only weakly, due to limited reinforcement from other secondary waves; and second, that diffraction by an edge was caused by interference between two rays: one reflected off the edge, and the other inflected while passing near the edge. The latter ray would be undeviated if sufficiently far from the edge, but Young did not elaborate on that case. These were the earliest suggestions that the degree of diffraction depends on wavelength. Later, in the 1803 Bakerian Lecture, Young ceased to regard inflection as a separate phenomenon, and produced evidence that diffraction fringes "inside" the shadow of a narrow obstacle were due to interference: when the light from one side was blocked, the internal fringes disappeared. But Young was alone in such efforts until Fresnel entered the field.
Huygens, in his investigation of double refraction, noticed something that he could not explain: when light passes through two similarly oriented calcite crystals at normal incidence, the ordinary ray emerging from the first crystal suffers only the ordinary refraction in the second, while the extraordinary ray emerging from the first suffers only the extraordinary refraction in the second; but when the second crystal is rotated 90° about the incident rays, the roles are interchanged, so that the ordinary ray emerging from the first crystal suffers only the extraordinary refraction in the second, and vice versa. This discovery gave Newton another reason to reject the wave theory: rays of light evidently had "sides". Corpuscles could have sides (or "poles", as they would later be called); but waves of light could not, because (so it seemed) any such waves would need to be longitudinal (with vibrations in the direction of propagation). Newton offered an alternative "Rule" for the extraordinary refraction, which rode on his authority through the 18th century, although he made "no known attempt to deduce it from any principles of optics, corpuscular or otherwise."
In 1808, the extraordinary refraction of calcite was investigated experimentally, with unprecedented accuracy, by Étienne-Louis Malus, and found to be consistent with Huygens's spheroid construction, not Newton's "Rule". Malus, encouraged by Pierre-Simon Laplace, then sought to explain this law in corpuscular terms: from the known relation between the incident and refracted ray directions, Malus derived the corpuscular velocity (as a function of direction) that would satisfy Maupertuis's "least action" principle. But, as Young pointed out, the existence of such a velocity law was guaranteed by Huygens's spheroid, because Huygens's construction leads to Fermat's principle, which becomes Maupertuis's principle if the ray speed is replaced by the reciprocal of the particle speed! The corpuscularists had not found a "force" law that would yield the alleged velocity law, except by a circular argument in which a force acting at the "surface" of the crystal inexplicably depended on the direction of the (possibly subsequent) velocity "within" the crystal. Worse, it was doubtful that any such force would satisfy the conditions of Maupertuis's principle. In contrast, Young proceeded to show that "a medium more easily compressible in one direction than in any direction perpendicular to it, as if it consisted of an infinite number of parallel plates connected by a substance somewhat less elastic" admits spheroidal longitudinal wavefronts, as Huygens supposed.
But Malus, in the midst of his experiments on double refraction, noticed something else: when a ray of light is reflected off a non-metallic surface at the appropriate angle, it behaves like "one" of the two rays emerging from a calcite crystal. It was Malus who coined the term polarization to describe this behavior, although the polarizing angle became known as Brewster's angle after its dependence on the refractive index was determined experimentally by David Brewster in 1815. Malus also introduced the term "plane of polarization". In the case of polarization by reflection, his "plane of polarization" was the plane of the incident and reflected rays; in modern terms, this is the plane "normal" to the "electric" vibration. In 1809, Malus further discovered that the intensity of light passing through "two" polarizers is proportional to the squared cosine of the angle between their planes of polarization (Malus's law), whether the polarizers work by reflection or double refraction, and that "all" birefringent crystals produce both extraordinary refraction and polarization. As the corpuscularists started trying to explain these things in terms of polar "molecules" of light, the wave-theorists had "no working hypothesis" on the nature of polarization, prompting Young to remark that Malus's observations "present greater difficulties to the advocates of the undulatory theory than any other facts with which we are acquainted."
Malus died in February 1812, at the age of 36, shortly after receiving the Rumford Medal for his work on polarization. In August 1811, François Arago reported that if a thin plate of mica was viewed against a white polarized backlight through a calcite crystal, the two images of the mica were of complementary colors (the overlap having the same color as the background). The light emerging from the mica was ""de"polarized" in the sense that there was no orientation of the calcite that made one image disappear; yet it was not ordinary (""un"polarized") light, for which the two images would be of the same color. Rotating the calcite around the line of sight changed the colors, though they remained complementary. Rotating the mica changed the "saturation" (not the hue) of the colors. This phenomenon became known as chromatic polarization. Replacing the mica with a much thicker plate of quartz, with its faces perpendicular to the optic axis (the axis of Huygens's spheroid or Malus's velocity function), produced a similar effect, except that rotating the quartz made no difference. Arago tried to explain his observations in "corpuscular" terms.
In 1812, as Arago pursued further qualitative experiments and other commitments, Jean-Baptiste Biot reworked the same ground using a gypsum lamina in place of the mica, and found empirical formulae for the intensities of the ordinary and extraordinary images. The formulae contained two coefficients, supposedly representing colors of rays "affected" and "unaffected" by the plate—the "affected" rays being of the same color mix as those reflected by amorphous thin plates of proportional, but lesser, thickness. Arago protested, declaring that he had made some of the same discoveries but had not had time to write them up. In fact the overlap between Arago's work and Biot's was minimal, Arago's being only qualitative and wider in scope (attempting to include polarization by reflection). But the dispute triggered a notorious falling-out between the two men. Later that year, Biot tried to explain the observations as an oscillation of the alignment of the "affected" corpuscles at a frequency proportional to that of Newton's "fits", due to forces depending on the alignment. This theory became known as "mobile polarization". To reconcile his results with a sinusoidal oscillation, Biot had to suppose that the corpuscles emerged with one of two permitted orientations, namely the extremes of the oscillation, with probabilities depending on the phase of the oscillation. Corpuscular optics was becoming expensive on assumptions. But in 1813, Biot reported that the case of quartz was simpler: the observable phenomenon (now called optical rotation or "optical activity" or sometimes "rotary polarization") was a gradual rotation of the polarization direction with distance, and could be explained by a corresponding rotation ("not" oscillation) of the corpuscles.

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.