## Sunday 25 August 2024

### On This Day in Math - August 25

The lecturer should give the audience full reason to believe that all his powers
have been exerted for their pleasure and instruction.

The 237th day of the year; it would be a singularly uninteresting number (3 x 79) except that the room number in the film, "The Shining" was switched from 217 in the novel to 237 for the film? It seems that the Timberline Lodge had a room 217 but no room 237, so the hotel management asked Kubrick to change the room number because they were afraid their guests might not want to stay in room 217 after seeing the film. *Visual Memory.co.uk

237 is a congruent number, it is the area of a right triangle with rational sides. Can you find such a triangle?

Derek Orr added, 237 = 44th prime + 44 = 193 + 44 What's the next number that equals the n-th prime + n?

237 is the difference of two consecutive squares, like all odd integers, 119^2 - 118^2 = 237, but also 41^2 - 38^2 because 6*38+9 = 237.

The 237th square pyramidal number, 4465475, is also a sum of two smaller square pyramidal numbers. There are only four smaller numbers (55, 70, 147, and 226) with the same property. *Wikipedia

237 is a lucky number, it remains after all sieves in the Eratosthenes-like Sieve of Stan Ulam. " Start with the natural numbers. Delete every 2nd number, leaving 1 3 5 7 ...; the 2nd number remaining is 3, so delete every 3rd number, leaving 1 3 7 9 13 15 ...; now delete every 7th number, leaving 1 3 7 9 13 ...; now delete every 9th number; etc." *OEIS

237 is the last of three consecutive odd numbers that have all prime digits.

237 not only has all prime digits, any sub-string of 2 consecutive digits also form a prime, 23, 37.

EVENTS

1609 Galileo leads a procession of Venetian Senators across the Piazza San Marco and up the Campanile for their first look through a telescope. In his words,

"to detect sails and vessels on the sea, so far away that coming under full sail toward the harbor, two hours or more passed before they could be seen without my eyeglass"

*Timothy Ferris, Coming of Age in the Milky Way
Thony Christie, the Renaissance Mathematicus suggests that his actually happened on the 21st of August. This was about two weeks after Thomas Harriott had drawn sketches of the moon through his telescope. Thony suggests that Galileo would not turn his telescope to the heavens for several more months.
He gives the 25th as the day that Galileo is granted a lifetime contract as professor for mathematics at the University of Padua with a salary of 1000 Florins but with the subsidiary clause that he would never receive a raise in salary.

 Fresco by Bertini of Galileo showing the Doge of Venice how to use the telescope *ESA space history

1664 Hooke writes to Boyle about new experiments he is performing in the damaged steeple of Old St. Pauls.  One involves a 180 foot long pendulum with a four pound weight that swings with a 12 second period. *Lisa Jardine, Ingenious Pursuits pg 65

1691 Edmund Halley delivers paper at Royal Society describing a diving bell he had built for exploration of the “Guynie Friggott”, a Royal African Company ship which foundered on the south coast near Pagham around 1 April 1691:
"The Diving tub [a truncate cone] was made 5 foot at Bottom where it was open, 3 foot at top and 5 foot deep… and under the bell by three ropes I fastned a stage about 2½ foot below to stand on… Within the bell I placed a bench about a foot from the bottom for the men below to sitt on when they should be cold and where a man might sett with all his clouths at any depth drie. I made likewise in the top of the bell a window to let in the light which was very thick and strong but as clear glass as could be gotten, and I placed a small Cock in the same crown of the bell to let out the hot & effete air unfitt for further respiration."

 *© Science Museum/Science & Society Picture Library,

Robert Hooke was unimpressed, declaring Halley’s paper “the Same wth what I Shewed ye Society 25 years Since”.   * Beverley Brown, Halley's Log Blog

1835 "The Great Moon Hoax" refers to a series of six articles that were published in The Sun, a New York newspaper, beginning on August 25, 1835, about the supposed discovery of life and even civilization on the Moon. The discoveries were falsely attributed to Sir John Herschel, perhaps the best-known astronomer
of his time.The story was advertised on August 21, 1835, as an upcoming feature allegedly reprinted from The Edinburgh Courant. The first in a series of six was published four days later on August 25.

BY SIR JOHN HERSCHEL, L.L.D. F.R.S. &c.
At the Cape of Good Hope
[From Supplement to the Edinburgh Journal of Science]"

The articles described fantastic animals on the Moon, including bison, goats, unicorns, bipedal tail-less beavers and bat-like winged humanoids ("Vespertilio-homo") who built temples. There were trees, oceans and beaches. These discoveries were supposedly made with "an immense telescope of an entirely new principle."

The author of the narrative was ostensibly Dr. Andrew Grant, the traveling companion and amanuensis of Sir John Herschel, but Grant was fictitious.
Portrait of a man-bat ("Vespertilio-homo"), from an edition of the Moon series published in Naples

Eventually, the authors announced that the observations had been terminated by the destruction of the telescope, by means of the Sun causing the lens to act as a "burning glass," setting fire to the observatory. *Wik

You can find all six articles here

1840  #OTD 182 years ago, on Aug 25, 1840: Joseph Gibbons, of Adrian, Michigan received a #patent for a "Grain Drill." It was the 1st practical seeding machine, combining a grain drill with openings & a volume regulating device to deliver seed. *The Nature of Invention @TnoiDoc

1875 Smithsonian Secretary Joseph Henry writes to Johns Hopkins President Daniel Gilman is first to suggest Sylvester for the proposed Chair of Mathematics: "Prof. Sylvester of London who intimates a willingness to accept a chair in your university provided one were tendered to him : he is one of the very first living mathematicians and his appointment would give a celebrity to the institution which would at once direct it to the attention of the whole scientific world." *Karen Hunger Parshall, David E. Rowe ; The Emergence of the American Mathematical Research Community, 1876-1900

1893 Eliakim Hastings Moore was apparently the first person to use the English word "field" in its modern mathematical sense and the first to allow for a finite field. He coined the expressions "field of order s" and "Galois-field of order s = qn." All were included in a paper presented to the Congress of Mathematics at Chicago #OTD. They would appear in print when the paper was published December in the Bulletin of the New York Mathematical Society. *Jeff Miller, Earliest Known Uses of Some of the Words of Mathematics

1955 The People’s Republic of China issued stamps honoring the mathematician Tsu Chung-chih (429–500), and astronomers Chang Heng (78–139) and Chong Sui (683–727) and physicist Li Shih-chen (1518–1593). [Scott #246, #245, #247, #248 respectively] *VFR

1959 The National Medal of Science was authorized by act of Congress (73 Stat. L. 431) for out-standing contribution in the physical, biological, mathematical, and engineering sciences on the basis or recommendation of the National Academy of Sciences. President Kennedy made the ﬁrst presentation February 17, 1963, to the Hungarian-born aerodynamicist Theodor von Karmen. [Kane, p. 373] Godel received one in 1975. Marston Morse did also. Did any other mathematicians? *VFR A list of laureates is here

1976 The Board of Governors of the MAA awarded an honorary life membership to Martin Gardner “for the substantial contributions he has made to the public appreciation of mathematics by his superb exposition in his texts and his column ‘Mathematical Games’ ” in the Scientiﬁc American. Gardner was both honored and embarrassed to receive this award, for he had never taken a mathematics course in college. “I consider myself more a journalist and popularizer of mathematics than a genuine mathematician.” While true, he has probability done more than anyone else to popularize mathematics. *VFR

In 1981, the U.S. spacecraft Voyager II came within 63,000 miles (100,000 km) of Saturn's cloud cover, sending back data and pictures of the ringed planet in its closest approach to Saturn, showing not a few, but thousands of rings. Photographs were also sent back of a number of Saturn's moons. The space probe was launched on 20 Aug 1977, and visited Jupiter on 9 Jul 1979, and continued on to Uranus (24 Jan 1986) and Neptune (25 Aug 1989) before leaving the Solar System. Having a nuclear power source, the space probe continues to study ultraviolet sources among the stars, and its fields and particles instruments continue to search for the boundary between the Sun's influence and interstellar space.*TIS

1996  Netscape Communications Corp. announced it had created a software company to enter an alliance with IBM, Oracle, and four Japanese electronics companies: Sony, Nintendo, Sega, and NEC. The new company, Navio Corp., is intended to compete with Microsoft Corp. in creating a new operating system. Netscape and Microsoft remain locked in a bitter battle over Microsoft's linking of its Internet Explorer World Wide Web browser with its Windows operating system, taking customers away from Netscape's Navigator browser. Netscape hoped the new company would develop a variety of computer applications, including video game systems, televisions, and network computers that would use its cheaper technology rather than Microsoft applications.

2012 Voyager 1 had crossed the heliopause and entered interstellar space on August 25, 2012, making it the first human-made object to do so. Moving with relative velocity to the Sun of about 17 km/s *Wik

2014 The Pluto-bound New Horizons spacecraft is now well over halfway through its journey to Pluto. Motoring along at 57,900 km/hr (36,000 mph), it will travel more than 4.8 billion km (3 billion miles) to fly past Pluto and its moons Nix, Hydra and Charon in July 2015.The next planetary milestone for New Horizons will be the orbit of Neptune, which it crosses on Aug. 25, 2014, exactly 25 years after Voyager 2 made its historic exploration of that giant planet. *Universe Today (Hat tip to David Dickinson@Astroguyz

A 1991 Pluto: Not Yet Explored stamp traveled more than 3 billion miles on a spacecraft to the dwarf planet has earned the GUINNESS WORLD RECORDS achievement for the farthest distance traveled by a postage stamp. The stamp also served as NASA’s rallying cry to set the record straight for exploring Pluto.

BIRTHS

1561 Philippe van Lansberge (25 August 1561 – 8 December 1632) was a Flemish clergyman who wrote on mathematics and astronomy. He calculated π to 28 places by a new method. Lansberge's work on astronomy followed Copernicus. He wrote works supporting Copernicus's theories in both 1619 and 1629. However he did not accept Kepler's ellipse theories and he published astronomical tables which he hoped would support Copernicus over Kepler. *SAU He may also have been one of the earliest (1604) to write Q.E.D to abbreviate the Latin phrase "quod erat demonstrandum". *Wik Does anyone have information on what his "new method" for calculating pi was?

 *Linda Hall Org

1699 Charles-Étienne Camus (25 August 1699 – 2 February 1768) was a French mathematician who worked on mechanics and cartography and published an important textbook: Cours de mathématiques.*SAU

1844 Thomas Muir (25 August 1844 – 21 March 1934) He is noted for a four volume work on the history of determinants. *VFR He also proved an important lemma about determinants of skew symmetric matrices.

At the University of Glasgow he changed his studies from classics to mathematics after advice from the future Lord Kelvin. After graduating he held positions at the University of St Andrews and the University of Glasgow. From 1874 to 1892 he taught at Glasgow High School. In 1882 he published Treatise on the theory of determinants; then in 1890 he published a History of determinants. In his 1882 work, Muir rediscovered an important lemma that was first proved by Cayley 35 years earlier: In Glasgow he lived at Beechcroft in the Bothwell district.[

In 1874 he was elected a Fellow of the Royal Society of Edinburgh, His proposers were William Thomson, Lord Kelvin, Hugh Blackburn, Philip Kelland and Peter Guthrie Tait. He won the Society's Keith Prize for 1881-1883 and a second time in 1895–1897. He served as the Society's Vice President 1888 to 1891. He won the Gunning Victoria Jubilee Prize for 1912 to 1916.

1867 Gury Vasilievich Kolosov (25 August 1867 - 7 November 1936) was a Russian mathematician who worked on the theory of elasticity.*SAU In 1907 Kolosov derived the solution for stresses around an elliptical hole. It showed that the concentration of stress could become far greater, as the radius of curvature at an end of the hole becomes small compared with the overall length of the hole.*Wik

1867 Hendrik De Vries (25 Aug 1867 in Amsterdam, The Netherlands - 3 March 1954 in Binyamina, Israel)"Paul Bockstable describes de Vries's contributions:

Even greater emphasis was placed on the historical development of mathematical sciences in the historical writings of Hendrik de Vries (1867-1954), professor at the Municipal University of Amsterdam. His lectures took in algebra and analysis, but from 1921-22 onwards, he focussed increasingly on his preferred field, giving public lectures on the development of geometry. These culminated in a series of articles in the Nieuw Tijdschrift voor Wiskunde (New Journal of Mathematics), which were later collected, together with some other items, in a three volume publication entitled 'Historische Studien' (1926). De Vries wrote in the introduction that he wanted to focus attention on the historical development of very precisely defined topics, even specific problems or theorems. He pointed out the didactic benefits that the historical approach to mathematical problems could offer.

He continued to publish Historical studies, and as examples we give the title of a small number of these later articles: On the contact and intersection of circles and conic sections (1946), How analytic geometry became a science (1948), On the infinite and the imaginary, or "surrealism" in mathematics (1949), and On relations and transformations (1949).*SAU

1880
Joshua Lionel Cowen
(25 Aug 1880; 8 Sep 1965) American inventor of electric model trains who founded the Lionel Corporation (1901), which became the largest U.S. toy train manufacturer. At age 18, he had invented a fuse to ignite the magnesium powder for flash photography, which the Navy Department bought from him to be a fuse to detonate submarine mines. He designed an early battery tube light, but without practical application. (His partner, Conrad Hubert, to whom he gave the rights improved it and founded the Eveready Flashlight Company.) At age 22, he created a battery-powered train engine intended only as an eye-catcher for other goods in a store window. To his surprise, many customers wanted to purchase the toy train. Thus he started a model railroad company. *TIS (For Xander)

1898 Helmut Hasse (25 August 1898 – 26 December 1979) was a German mathematician working in algebraic number theory, known for fundamental contributions to class field theory, the application of p-adic numbers to local classfield theory and diophantine geometry (Hasse principle), and to local zeta functions.

1902 Seishi Kikuchi (August 25, 1902 – November 12, 1974) was a Japanese physicist, known for his explanation of the Kikuchi lines that show up in diffraction patterns of diffusely scattered electrons. *Wik

1904 Cecil John Alvin Evelyn (25 August 1904 in London, England, 24 May 1976 in Deptford, Kent, England) He graduated with a B.A. in 1927. At Oxford he had become friendly with Hubert Linfoot who was one year older than Evelyn. Linfoot graduated in 1926 but had remained at Oxford undertaking research advised by G H Hardy. Both Evelyn and Linfoot were interested in number theory at this time and they worked together.

Between 1929 and 1933, Evelyn and Linfoot produced six joint papers, all with the title On a problem in the additive theory of numbers.
A book was to be Evelyn's final mathematical publication. He published the book (with G B Money-Coutts and J A Tyrrell) The seven circles theorem and other new theorems (1974) which was translated into French and published as (with G B Money-Coutts and J A Tyrrell) Le théorème des sept cercles (1975). R D Nelson, Ampleforth College, York, writes :-

This elegant book will please all geometers, amateur and professional, and deserves a place in every library. Using a variety of essentially elementary methods, the authors present and prove a number of new or little known theorems in plane geometry. To emphasise the aesthetic appeal of these results and to assist the argument in places, over forty of its pages carry diagrams of high quality. The book has three independent sections but the style of writing is uniform. The authors invite and sometimes require the co-operation of the reader as he works through the book and, in this way, they prepare him for the intricacies of the final and most difficult section. The first part re-introduces an algebra of vectors, due to Silberstein, in which the laws of addition and equivalence are such that few of the usual properties are obvious. For example, associativity of addition requires two applications of Desargues' theorem for its proof. No use is made of this algebra. The second section opens with a delightful new theorem concerning seven Pascal lines derived from a heptagon inscribed in a conic. This is followed by a number of extensions and generalisations of the theorems of Pascal and Brianchon. ... Finally there are four new theorems about closed chains of six circles ... In the first theorem each circle touches a seventh, in the second the circles alternately touch a pair of parallel lines, in the third each circle touches two of the sides of a triangle and in the fourth each circle touches two out of three fixed circles making a configuration of nine circles in all. The first theorem, beautifully proved by inversion, gives the book its title.

The remarkable thing about this book is that the theorem of the title is an elementary geometry theorem which appears to have been first discovered by the authors of this book. The theorem concerns six circles, all inside and touching a seventh circle. These six circles all touch each other. Join each of the six points on the outer circle where the six inner circles touch it, to the point of contact directly opposite it. The theorem states that these three lines are concurrent. *SAU

1924 Harlan James Smith (August 25, 1924 – October 17, 1991)

Harlan J. Smith was an American astronomer born in Wheeling, West Virginia, the son of Paul and Anna McGregor Smith.
In 1963 he was named chair of the University of Texas astronomy department where he also became the director of the McDonald Observatory. At the observatory he oversaw the construction of the 2.7m telescope he had persuaded NASA to build in support of planetary missions. From 1966 until 1970 he was a member of the Committee on the Large Space Telescope, an ad hoc group formed by the National Academy of Sciences, the work of which resulted in the Hubble Space Telescope. He also was the chairperson of the NASA Space Science Board from 1977 until 1980, and there helped propose NASA's Great Observatories program. He retired in 1989.
During his career he studied variable stars, the radio emission from planets, as well as photometry and astronomical instruments. With Dorrit Hoffleit, he was the first to observe the optical variability of quasars, and discovered a class of variable stars known as Delta Scuti variables.
He was an enthusiastic proponent of educating the public on astronomy, and developed the radio program "Star Date". He also developed "The Story of the Universe", a series of educational films. He was also a proponent of international cooperation, particularly with China which he visited several times. He served as co-editor of the Astronomical Journal as well as acting secretary for the American Astronomical Society. *TIA

1964 Maxim Lvovich Kontsevich (25 August 1964) is a Russian mathematician. He is a professor at the Institut des Hautes Études Scientifiques and a distinguished professor at the University of Miami. He received the Henri Poincaré Prize in 1997, the Fields Medal in 1998, and the Crafoord Prize in 2008. His work concentrates on geometric aspects of mathematical physics, most notably on knot theory, quantization, and mirror symmetry. His most famous result is a formal deformation quantization that holds for any Poisson manifold. He also introduced knot invariants defined by complicated integrals analogous to Feynman integrals. In topological field theory, he introduced the moduli space of stable maps, which may be considered a mathematically rigorous formulation of the Feynman integral for topological string theory. These results are a part of his "contributions to four problems of geometry" for which he was awarded the Fields Medal in 1998. *Wik

DEATHS

1679 Jonas Moore was an English man of science important for his support of mathematics and astronomy.*SAU He seems to have been the first to use "cot" for the cotangent function. He also founded the Royal Mathematical School at Christ's Hospital with Samual Pepys to train young men in the mathematics of navigation. *Wik He made critical contributions to the draining of the fens in England (making my drive from Lakenheath to Stoke Ferry much easier) and was instrumental in convincing Charles II to create the Royal Observatory and appoint Flamsteed as Astronomer Royal. *The day that Jonas died, Renaissance Mathematicus.

1819 James Watt (19 Jan 1736,25 Aug 1819) Scottish instrument maker and inventor whose steam engine contributed substantially to the Industrial Revolution. In 1763 he repaired the model of Newcomen's steam engine belonging to Glasgow University, and began experiments on properties of steam. The Newcomen engine was simple in design: it acted as a pump and a jet of cold water was used to condense the steam. Watt improved on this design by adding a separate condenser and a system of valves to make the piston return to the top of the cylinder after descending. He took out a patent for the separate condenser in 1769. He later adapted the engine to rotary motion, making it suitable for a variety of industrial purposes, and invented the flywheel and the governor.*TIS

1822 Sir William (Frederick) Herschel (15 Nov 1738, 25 Aug 1822) German-born British astronomer, the founder of sidereal astronomy for the systematic observation of the heavens. In 1773, Herschel made and began using his first telescope. With it he began a project that would continue for the rest of his life: that of systematically studying the sky. Through this study he discovered the planet Uranus, many new nebulae, clusters of stars and binary stars. Herschel hypothesized that nebulae are composed of stars, developed a theory of stellar evolution and was the first person to correctly describe the form of our Galaxy, the Milky Way. He discovered the Saturnian satellites Mimas and Enceladus (1789) and the Uranian satellites Titania and Oberon (1787). He was probably the most famous astronomer of the 18th century.*TIS

1867 Michael Faraday(22 September 1791 – 25 August 1867) died at Hampton Court, Middlesex, England. English physicist and chemist whose many experiments contributed greatly to the understanding of electromagnetism. Although one of the greatest experimentalists, he was largely self-educated. Appointed by Sir Humphry Davy as his assistant at the Royal Institution, Faraday initially concentrated on analytical chemistry, and discovered benzene in 1825. His most important work was in electromagnetism, in which field he demonstrated electromagnetic rotation and discovered electromagnetic induction (the key to the development of the electric dynamo and motor). He also discovered diamagnetism and the laws of electrolysis. He published pioneering papers that led to the practical use of electricity, and he advocated the use of electric light in lighthouses. *TIS

1908 Antoine-Henri Becquerel (15 Dec 1852, 25 Aug 1908) Antoine-Henri Becquerel was a French physicist who discovered radioactivity. In 1903 he shared the Nobel Prize for Physics with Pierre and Marie Curie. His early researches were in optics, then in 1896 he accidentally discovered radioactivity in fluorescent salts of uranium. He left some uranium mineral crystals in a drawer on a plate in black paper. Later, he developed the plate and found it was fogged, even though the crystals without ultraviolet radiation from sunlight were not fluorescing. Thus the salt was a source of a penetrating radiation. Three years afterwards he showed that it consists of charged particles that are deflected by a magnetic field. Initially, the rays emitted by radioactive substances were named after him. *TIS

1921 Peter Cooper Hewitt (May 5, 1861 – August 25, 1921) was an American electrical engineer and inventor, who invented the first mercury-vapor lamp in 1901. Hewitt was issued U.S. patent #682692 on September 17, 1901.
In 1902 Hewitt developed the mercury arc rectifier, the first rectifier which could convert alternating current power to direct current without mechanical means. It was widely used in electric railways, industry, electroplating, and high-voltage direct current (HVDC) power transmission. Although it was largely replaced by power semiconductor devices in the 1970s and 80s, it is still used in some high power applications.
In 1907 he developed and tested an early hydrofoil. In 1916, Hewitt joined Elmer Sperry to develop the Hewitt-Sperry Automatic Airplane, one of the first successful precursors of the UAV. *Wik

1956
George Washington Pierce
(11 Jan 1872, 25 Aug 1956) American inventor who was a pioneer in radiotelephony and a noted teacher of communication engineering. He did work that led to the practical application of a variety of experimental discoveries in piezoelectricity and magnetostriction. He developed the Pierce oscillator, which utilizes quartz crystal to keep radio transmissions precisely on the assigned frequency and to provide similar accuracy for frequency meters. His other accomplishments include the mathematical calculation of the radiation properties of radio antennae; invention of the mercury-vapor discharge tube, which was the forerunner of the thyratron; invention of a method of recording sound on film; and sound generation by bats and insects. *TIS

1997 Calogero Vinti ( Agrigento , 12 July 1926 – Perugia , 25 August 1997 ) was an Italian mathematician , student of Emilio Bajada . He majored in mathematics at the university of Palermo in 1949 , under the direction of prof. Michele Cipolla , Benedetto Pettineo, but above all Emilio Bajada . Still at the University of Palermo, he dealt with problems inherent to the study of partial differential equations . Professor of Mathematical Analysis since 1960 , from 1962 he taught at the University of Modena and Reggio Emilia until 1970 , when he became a professor at the University of Perugia . In Perugia he was also among the founders of the university faculty of engineering of which he was also the first dean .

The Vinti Prize awarded by the Italian Mathematical Union is dedicated to the memory of Calogero Vinti .

2005 Ruth Aaronson Bari (November 17, 1917 – August 25, 2005) was an American mathematician known for her work in graph theory and homomorphisms. The daughter of Polish-Jewish immigrants to the U.S., she was a professor at George Washington University beginning in 1966. She was the mother of environmental activist Judi Bari, science reporter Gina Kolata and art historian Martha Bari.*Wik

2012 Neil Alden Armstrong, (August 5, 1930, August 25, 2012) U.S. astronaut, was the first man to walk on the moon (20 Jul 1969, Apollo 11). He served as a Navy pilot during the Korean War, then joined the National Advisory Committee for Aeronautics (which became NASA), as a civilian test pilot. In 1962, he was the first civilian to enter the astronaut-training program. He gained experience as command pilot of the Gemini 8 mission, which accomplished the first physical joining of two orbiting spacecraft. Later he was commander of the Apollo 11 lunar mission. From 1971, he worked as professor of aerospace engineering at the University of Cincinnati. He was a member of the commission that investigated the 1986 Challenger space shuttle disaster.*TIS Armstrong died following complications resulting from cardiovascular procedures. *Mercury News

2016 – George Spencer-Brown (April 2, 1923, Grimsby, Lincolnshire, England, August 25, 2016  ) is a polymath best known as the author of Laws of Form. He describes himself as a "mathematician, consulting engineer, psychologist, educational consultant and practitioner, consulting psychotherapist, author, and poet.",*Wik
In a 1976 letter to the Editor of Nature, Spencer-Brown claimed a proof of the four-color theorem, which is not computer-assisted. The preface of the 1979 edition of Laws of Form repeats that claim, and further states that the generally accepted computational proof by Appel, Haken, and Koch has 'failed' (page xii). Spencer-Brown's claimed proof of the four-color theorem has yet to find any defenders; Kauffman provides a detailed review of parts of that work. *VFR

During his time at Cambridge,[clarification needed] Spencer-Brown was a chess half-blue. He held two world records as a glider pilot, and was a sports correspondent to the Daily Express.[9] He also wrote some novels and poems, sometimes employing the pen name James Keys.

Spencer-Brown died on 25 August 2016. He was buried at the London Necropolis, Brookwood, Surrey.

1931   James Watson Cronin (September 29, 1931 – August 25, 2016) American particle physicist, who shared (with Val Logsdon Fitch) the 1980 Nobel Prize for Physics for "the discovery of violations of fundamental symmetry principles in the decay of neutral K-mesons." Their experiment proved that a reaction run in reverse does not follow the path of the original reaction, which implied that time has an effect on subatomic-particle interactions. Thus the experiment demonstrated a break in particle-antiparticle symmetry for certain reactions of subatomic particles.*TIS

2020 Rebeca Guber was one of the first Argentinian women mathematicians. She played a major role in the development of computing in Argentina. She also made important contributions to education particularly teaching science in schools.

Credits :
*CHM=Computer History Museum
*FFF=Kane, Famous First Facts
*NSEC= NASA Solar Eclipse Calendar
*RMAT= The Renaissance Mathematicus, Thony Christie
*SAU=St Andrews Univ. Math History
*TIA = Today in Astronomy
*TIS= Today in Science History
*VFR = V Frederick Rickey, USMA
*Wik = Wikipedia