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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 t...
"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 centurie...
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...
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 opti...
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...
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" conta...
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. ...
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 Wisnovsk...
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 th...
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 ...
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 "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....
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 t...
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 c...
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 pres...
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. ...
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 b...
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...
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 a...
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 Counte...
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, Se...
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 ...
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 keen...
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 t...
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 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 con...
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 omitt...
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 ...
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 adequa...
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 kno...
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 a...
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-break...
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 unw...
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-...
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 probabl...
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 O...
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 ...
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 p...
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. ...
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 sta...
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 competito...
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 ...
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 A...
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 Aust...
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...
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...
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 losin...
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 ...
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...
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 ...
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 ...
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 w...
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 ...
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-spectrophotom...
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 hav...
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 founde...
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 deduc...
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 o...
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. Gettys...
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...
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...
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...
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. E...
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 o...
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, ...
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 basebal...
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 Ru...
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...
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 ...
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 ...
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 key...
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 fre...
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 co...
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 le...
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 wit...
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 produce...
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, ex...
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 ...
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 overmodul...
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 ...
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 f...
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...
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...
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 generat...
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 c...
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 ...
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...
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 M...
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 t...
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 con...
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 discove...
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 ...
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 perpend...
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 (whic...
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 on...
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 emergin...
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: fr...
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, a...
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 (t...
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 represen...

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