Thursday, 16 July 2026

On This Day in Math - July 16

   



Pure mathematics is the world's best game. 
It is more absorbing than chess, more of a gamble than poker, 
and lasts longer than Monopoly. 
It's free. It can be played anywhere 
- Archimedes did it in a bathtub.


-Richard J. Trudeau


The 197th day of this year; 197 is the sum of all digits of all two-digit prime numbers: 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.  It is simple to show that the sum of one-digit primes is 17. Do the sum of the digits of n-digit primes always end in seven? (http://oeis.org/A130817) Or perhaps we ask, are there any others that do?  A nice problem for students, look at the sum of all the primes of n digits and decide are there an odd or even number of primes with n digits.For example, the sum of all the four-digit primes is 19879, is the total number of four-digit primes odd or even?

197 is the smallest prime number that is the sum of 7 consecutive primes: 17 + 19 + 23 + 29 + 31 + 37 + 41 (student challenge: can there be a prime that is the sum of eight consecutive primes?)

197 is the seventh, and last, year-day that will be a Keith number   created in 1987 by Michael Keith.  (they are also repfigit numbers, the term he originally used for them. )

197 is the sum of the first twelve prime numbers: 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37

More Math facts for every year date here



EVENTS

433 B.C. The Metonic 19-year cycle of the moon enacted. This masterpiece of approximation (19 solar years = 235 lunations) is still used today in the computation of the date of Easter. [See A. Philip, The Calendar: Its History, Structure and Improvement, p. 8]*VFR  (I have also seen June 27, 432 BC given for this event.  Purist may choose up sides and argue for their choice)

The cycle was introduced in ancient Greece by Athenian astronomer Meton around 432 BC. The cycle consists of 235 lunations, or synodic months, and seven intercalated months. After this cycle, the moon's phases return on the same days of the solar year. 

Depiction of the 19 years of the Metonic cycle as a wheel, with the Julian date of the Easter New Moon, from a 9th-century computistic manuscript made in St. Emmeram's Abbey (Clm 14456, fol. 71r)




1661 Europe’s earliest modern-style banknotes, available to all and sundry with each note worth a fixed sum, were introduced by the Bank of Stockholm. The bank had been started in 1657 by Johan Palmstruch in close collaboration with the royal government which pocketed half the profits. It was Palmstruch who suggested the kreditivsedlar (credit notes) and they provided a welcome alternative to Sweden’s massive copper coins, which were dismayingly heavy and clumsy. Colloquially known as Palmstruchers the notes were printed on thick, white watermarked paper with the word banco as the watermark and carried the date, the bank’s seal and eight signatures, headed by Palmstruch’s, as an assurance of reliability. They were in stated denominations and payable to the bearer and anybody who had one was promised payment by the bank.  (*History Today )




1669  Wallis writes to Oldenburg complaining about the public perception of the Royal Society after Doctor Robert Smith's dedication of the New Theater consisted of only, "Satyrical invectives against Cromwell, Fanaticks, the Royal Society and Philosophy." *The mathematical work of John Wallis, D.D., F.R.S., (1616-1703) By Joseph Frederick Scott, pg 11


1730 The famous lines of Alexander Pope (1688–1744) which were intended as an epitaph for Newton:
Nature and Nature’s Laws lay hid in night: God said, Let Newton be! and all was light.
were published in the Grub-Street Journal, the first time they appeared in print. *VFR

The Grub-Street Journal, published from 8 January 1730 to 1738,was a satire on popular journalism and hack-writing as it was conducted in Grub Street in London.It was largely edited by the nonjuror Richard Russel and the botanist John Martyn. While he disclaimed it, Alexander Pope was one of its contributors, continuing his satire which he had started with The Dunciad.




1828 James Ryan recorded his copyright for The Differential and Integral Calculus, the first calculus book written by a U.S. citizen.*VFR

Ryan’s book preceded more famous American calculus texts by authors such as Benjamin Peirce (father of Charles Sanders Peirce), whose works came later in the 19th century.


  • His book was never widely adopted.
  • Within a decade it was eclipsed by Charles Davies' Elements of Differential and Integral Calculus (1836), which became the standard American calculus text for many years. 
  • Ryan appears to have left almost no other mathematical publications, and historians have found remarkably little biographical information about him. *Chatgpt





  • 1848 Exactly 50 years earlier, Gauss received his doctorate. As part of the show at the golden jubilee Gauss was to light his pipe with a manuscript page from his Disquisitiones Arithmeticae. His student Dirichlet was outraged by this sacrilege and boldly snatched the paper as a treasured memento. [Eves, History of Mathematics, p. 370]*VFR 

    There is no reliable contemporary source that confirms this anecdote. It appears to be one of those colorful tales that circulate in the lore of mathematics, possibly to highlight the contrast between Gauss’s aloof attitude toward his own work and the reverence shown by others like Dirichlet.




    1945 The first atomic bomb explosion was carried out in a test at Alamogordo Air Base in New Mexico, at 12:29:15 G.C.T.  *VFR The atomic bomb was invented by two refugee German scientists in Britain, Professor Rudolph Peierls and Otto Frisch, of Birmingham University. They designed a "blue-print" for making an atom bomb in 1940. It actually began when the Italian-born physicist Enrico Fermi, working in the United States, invented an apparatus which produced the first atomic chain reactions. In 1940 both the Americans and British were researching the atom bomb and when the United States entered WW2, the British joined the American "Manhattan Project" and production of the bomb went on ahead in the US.*TIS


    1969  Apollo 11 lifts off.  Launched by a Saturn V rocket from Kennedy Space Center in Merritt Island, Florida on July 16, Apollo 11 was the fifth manned mission of NASA's Apollo program. It would result in the first astronauts to land on the Moon on July 20, 1969. *Wik




    In 1994, the first of 21 asteroids, major fragments of the comet Shoemaker-Levy 9 broken-up 2 years earlier, hit Jupiter, creating a 1200-mile wide fireball 600 miles high to the joy of astronomers awaiting the celestial fireworks, giving scientists their first chance to observe such a collision as it happened, and others through July 22. Jupiter is a gas giant, made up mostly of hydrogen and helium in gas and liquid form.When we observe Jupiter, we are looking not at a solid surface, but a banded atmosphere with swirling clouds and huge storms.*TIS


    1995 Amazon.com, incorporated a year earlier by Jeff Bezos in Washington (state) as an online bookstore, sells its first book, Douglas Hofstadter's Fluid Concepts and Creative Analogies: Computer Models of the Fundamental Mechanisms of Thought. *Wik


    2186 (In case you live a really long time) will be the Closest approach to maximum possible duration of totality with 7 min 29 sec in the Atlantic Ocean. Maximum theoretical
    duration is 7 min 31 sec. During the 4th millennium there are only 2 solar eclipses with maximum duration of totality longer than 7 min. In the years 3973 and 3991. There are none in 21st century. *NSEC


    BIRTHS

    1678 Jakob Hermann (16 July 1678, Basel – 11 July 1733, Basel) was a Swiss mathematician who made contributions to dynamics.*SAU In 1729, he proclaimed that it was as easy to graph a locus on the polar coordinate system as it was to graph it on the Cartesian coordinate system. However, no one listened. He was a distant relative of Leonhard Euler. 

    He appears to have been the first to show that the Laplace–Runge–Lenz vector is a constant of motion for particles acted upon by an inverse-square central force.*Wik



    1689 Samuel Molyneux FRS (16 July 1689 – 13 April 1728) was an amateur astronomer and politician who sat in the British House of Commons between 1715 and 1728 and in the Irish House of Commons from 1727 to 1728. His work with James Bradley attempting to measure stellar parallax led to the discovery of the aberration of light. The aberration was the first definite evidence that the earth moved and that Copernicus and Kepler were correct. In addition to his astronomical works, Molyneux wrote about the natural history and other features of Ireland.

    Bradley and Molyneux began their work in 1725, and they never did observe stellar parallax – it was too small for even their instrument to detect. But they did observe another unexpected slight annual motion of their target star, known as gamma Draconis. Bradley ultimately realized that it was a result of the fact that light moves with a finite speed, so that if the earth is moving across the path of the light, the result is a slight sideways deflection of the light. He called this new phenomenon the "aberration of light," and he announced it in a paper of 1729. It was one of the very first proofs that the earth moves through space. It is unfortunate that Molyneux, who should have shared in the approbation, had collapsed and died the previous year, at the age of only 38. Molyneux’s original telescope has disappeared, but Bradley ordered another from the same instrument maker for himself, just 12 feet long, and that one does survive, in the National Maritime Museum

     He died in suspicious circumstances.  Molyneux had married Lady Elizabeth Capel, daughter of Algernon Capell, 2nd Earl of Essex, on 5 April 1717. In 1728, he suffered a fit while in the House of Commons. He was treated by court anatomist Nathaniel St André, but the treatment did not prove successful, and Molyneux died in Kew in April. On the night of the death, St André eloped with Molyneux's wife, Elizabeth, the two marrying in 1730. Samuel Madden, a relative of Molyneux's, claimed that St André had poisoned the MP. Although St André won an action for defamation, he found himself unable to secure regular work.

    Molyneux’s telescope replacement 



    1746 Giuseppe Piazzi (July/June? 16, 1746 – July 22, 1826) Italian astronomer and author, born in Valtellina, discovered the first asteroid - Ceres. He established an observatory at Palermo and mapped the positions of 7,646 stars. He also discovered that the star 61 Cygni had a large Proper Motion, which led Bessel to chose it as the object of his parallax studies. He discovered Ceres on 1 Jan 1801, but was able to make only three observations. The term "asteroid," meaning "star-like" was coined (1803) by Herschel. Fortuitously, Gauss had recently developed mathematical techniques that allowed the orbit to be calculated. Within the next few years, astronomers discovered three more asteroids: Pallas, Juno, and Vesta. The thousandth Asteroid discovered was named Piazzi in his honor.*TIS

    Modelled shape of Piazzia from its lightcurve  



    *Wik



    1801 Julius Plücker (16 June 1801 – 22 May 1868)  German mathematician and physicist whose work suggested the far-reaching principle of duality, which states the equivalence of certain related types of theorems. He also discovered that cathode rays (electron rays produced in a vacuum) are diverted from their path by a magnetic field, a principle vital to the development of modern electronic devices, such as television. At first alone and later with the German physicist Johann W. Hittorf, Plücker made many important discoveries in spectroscopy. Before Bunsen and Kirchhoff, he announced that spectral lines were characteristic for each chemical substance and this had value to chemical analysis. In 1862 he pointed out that the same element may exhibit different spectra at different temperatures. *TIS




    1819 Siegfried Heinrich Aronhold (16 July 1819 Angerburg, East Prussia – 13 March 1884, Berlin, Germany) was a German mathematician who worked on invariant theory and introduced the symbolic method.*Wik


    1866 Edwin Brant Frost II (July 16, 1866 – May 14, 1935) American astronomer, born in Brattleboro, Vermont. His father, Carlton Pennington Frost, was dean of Dartmouth Medical School.
    Frost joined the staff of Yerkes Observatory in 1898 and became its director in 1905 when George Hale resigned. Frost kept the position until his retirement in 1932. He was the editor of the Astrophysical Journal from 1902 to 1932, known for his careful attention to details. In 1915 he lost the use of his right eye and in 1921, his left. Despite his blindness he continued working for eleven more years until his retirement in 1932.
    Frost's research focused on the determination of radial velocity using stellar spectroscopy and spectroscopic binaries. In 1902, he discovered the strange behavior of Beta Cephei, which later became the prototype for Beta Cephei variable stars. *TIA




    1888 Frits Zernike (16 July 1888 – 10 March 1966) Dutch physicist who was awarded the Nobel Prize for Physics in 1953 for his invention of the phase-contrast microscope, an instrument that permits the study of internal cell structure without the need to stain and thus kill the cells. In addition to its capacity to render colourless and transparent objects visible in the microscope, it also enables one to detect slight flaws in mirrors, telescope lenses, and other instruments indispensable for research. In this connection, Zernike's phase-plate serves as an indicator which locates and measures small surface irregularities to a fraction of a light-wavelength.*TiS



    1902 Gheorghe Calugareanu (16 July 1902 - 15 November 1976)As a lecturer, Calugareanu gave simple, clear explanations. He spoke quietly and he would start every lecture by spending ten minutes going over the material from the previous lecture. At the end of the lecture he would explain what was coming in the next lecture. This makes it sound as if he would make little progress, but on the contrary, he was able to go steadily though the material. Students really understood the lectures as he gave them and his lectures were models for the highest quality of teaching. His research was elegant and his personality shone through his mathematical papers as it did in his teaching. Some of his results had applications in molecular biology or fluid mechanics. In fact Calugareanu spoke of about the tension between pure and applied mathematics in his autobiographical paper . He remarks there that, in Communist Romania, the party and the state stress the importance of research which leads to improvements in the conditions of life. However, they also recognize the importance of fundamental research as a foundation for and preliminary to applications. The paper allows us to glimpse other aspects of Calugareanu's approach to mathematics. He addresses younger mathematicians explaining that because of the rapid expansion in mathematics there is great importance in having a guiding thread or theme in one's research. This, he explains, is especially true if one's work spans several fields. His own work did indeed span several fields, and he recognises that his thread was the idea of invariance which ran through his work in complex variables, differential topology, and modern algebra.*SAU




    1903 Irmgard Flugge-Lotz (6 July 1903 - 22 May 1974)born in Hameln, Germany. Her father encouraged her in mathematics, but she chose engineering because “I wanted a life which would never be boring—a life in which new things would always occur.” She studied applied mathematics at the Technical University of Hanover and in 1929 she became a Doktor-Ingenieur, the equivalent of an American Ph.D. in Engineering. She made contributions to aerodynamics, control theory, and fluid mechanics. In 1960 she became full professor at Stanford. *WM




    1951 Daniel Singer Bricklin (born July 16, 1951; ) is an American businessman and engineer who is the co-creator, with Bob Frankston, of VisiCalc, the first spreadsheet program. He also founded Software Garden, Inc., of which he is currently president, and Trellix, which he left in 2004. He currently serves as the chief technology officer of Alpha Software.

    His book, Bricklin on Technology, was published by Wiley in May 2009. For his work with VisiCalc, Bricklin is often referred to as “the father of the Spreadsheet.” He was one of 6 people spotlighted when the Computer was denoted "Machine of the Year" by Time magazine in 1982.








    DEATHS

    1739 Charles François de Cisternay Du Fay (14 September 1698 – 16 July 1739) was a French chemist who made early experiments in electricity. In 1733, he distinguished electrical fluid in two types he named "vitreous electricity" and "resinous electricity" depending on the objects that produced the charge (subsequently called "positive" and "negative" by Benjamin Franklin). Du Fay discovered that objects with like charges repel each other, but oppositely charged objects repel. He also noted the effect of electricity shock on his body, and visible spark when making contact with a highly charged object. He observed that electricity may be conducted in the gaseous matter (now called plasma) adjacent to a red-hot body. Du Fay was also a pioneer in crystal optics.*TIS




    1981 Jacob Wolfowitz (March 19, 1910 – July 16, 1981) was a Polish-born American statistician and Shannon Award-winning information theorist. He was the father of former Deputy Secretary of Defense and World Bank Group President Paul Wolfowitz.
    While a part-time graduate student, Wolfowitz met Abraham Wald, with whom he collaborated in numerous joint papers in the field of mathematical statistics. This collaboration continued until Wald's death in an airplane crash in 1950. In 1951, Wolfowitz became a professor of mathematics at Cornell University, where he stayed until 1970. He died of a heart attack in Tampa, Florida, where he was a professor at the University of South Florida.
    Wolfowitz's main contributions were in the fields of statistical decision theory, non-parametric statistics, sequential analysis, and information theory.*Wik



    1994 Julian Seymour Schwinger (February 12, 1918 – July 16, 1994) American physicist who shared the 1965 Nobel Prize in Physics for his contributions to quantum electrodynamics (with Richard Feynman and Shin-Itiro Tomonaga). Schwinger worked on reconciling quantum mechanics with Albert Einstein's special theory of relativity. He published his first physics paper at the age of sixteen. During WW II, he developed important methods in electromagnetic field theory, which advanced the theory of wave guides. His variational techniques were applied in several fields of mathematical physics. In the 1940's he was one of the inventors of the "renormalization" technique. In 1957, he proposed that theoretically there were two different neutrinos: one associated with the electron and one with the muon. Later experimental work provided verification. He invented source theory. *TIS  Schwinger was Oppenheimer's most brilliant student. Oppenheimer once said of him, "When ordinary people give a talk, they tell you how to do it.  When Julian gives a talk, it is to tell you that only he can do it." *Freeman Dyson, Infinities in all Directions.




    2005  Magdalena Araceli Mouján Otaño (26 March 1926, 16 July 2005)  Mouján was born in Pehuajó (Buenos Aires Province), the granddaughter of Basque writer Pedro Mari Otaño [eu]. After studying mathematics at the National University of La Plata, she completed a doctorate in 1950.

    In 1957, Mouján became one of four founding members of an operations research group funded by the Argentine Army and led by mathematician Agustín Durañona y Vedia. In the 1960s, she joined the National Atomic Energy Commission and began using the Clementina computer [es], the first scientific computer in Argentina, at the University of Buenos Aires. Her calculations were used to help build the RA-1 Enrico Fermi nuclear reactor.

    Mouján began writing science fiction in the early 1960s under a pseudonym, "Inge Matquim". A science fiction story by Mouján, "Los Huáqueros", won joint first prize at Mardelcon, the 1968 Argentine science fiction convention.

    Another of her stories, "Gu ta Gutarrak" (Basque for "we and ours"), was written in homage to her grandfather's 1899 poem of the same title, and as "a satire of the Basque nationalist myth of the antiquity and purity of the Basque race". It describes the adventures of a time-traveling Basque family who return to their homeland in the time of their ancestors. The story was accepted for a 1970 issue of the Spanish science fiction magazine Nueva Dimensión, but its publication was blocked by the Franco regime as being contrary to the ideals of Spanish unity. The story was translated into multiple languages, and finally republished by Nueva Dimensión in 1979, after Franco's death. *Wik




    2013 Yuri Vasilyevich Prokhorov (15 December 1929 – 16 July 2013) was a Soviet and Russian mathematician, active in the field of probability theory. He was a PhD student of Andrey Kolmogorov at the Moscow State University, where he obtained his PhD in 1956.

    Prokhorov became a corresponding member of the Academy of Sciences of the Soviet Union in 1966, a full member in 1972. He was a vice-president of the IMU. He received Lenin Prize in 1970, Order of the Red Banner of Labour in 1975 and 1979. He was also an editor of the Great Soviet Encyclopedia. *Wik







    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
    *WM = Women of Mathematics, Grinstein & Campbell

    Wednesday, 15 July 2026

    On This Day in Math - July 15

     



    Mathematics is as much an aspect of culture as it is a collection of algorithms.

    -Carl Boyer


    The 196th day of the year, A Lychrel number is a natural number which cannot form a palindromic number through the iterative process of repeatedly reversing its base 10 digits and adding the resulting numbers. 196 is the lowest number conjectured to be a Lychrel number; the process has been carried out for one billion iterations without finding a palindrome, but no one has ever proven that it will never produce one. The number produced on the one billionth iteration had 413,930,770 digitsThe name "Lychrel" was coined by Wade VanLandingham—a rough anagram of his girlfriend's name Cheryl. No Lychrel numbers are known, though many numbers are suspected Lychrels, the smallest being 196. (Students might try finding the number of iterations of the process to find a palindrome for various n. 195, for example, takes four iterations :
    195 + 591 = 786
    786 + 687 = 1473
    1473 + 3741 = 5214
    5214 + 4125 = 9339)
    DO not try the numbers 89 or 98. Harry J Saal used a computer to repeatedly iterate this process and finally did come up with a palindrome, the number 8,813,200,023,188 on the 24th iteration.

    Jim Wilder noticed that 142 =196 and 132=169... are there other squares of consecutive numbers that share the same digits?

    and a palindromic expression of 196 using only its digits, 19 + 16 +  9 + 61 + 91  OR 96 +1 + 9 + 11 + 9 + 1 + 69 


    A number is said to be square-full if for every prime, p, that divides it, p2 also divides it. 196 is such a number, 196 = 2^2 x 7^2   Are there cube-full numbers? (of course there are, but what are they? 8 would be, as would any cube, I guess smallest with more than one is 6^3 = 216, coming up soon)

    More Math facts for every year date here



    EVENTS


    622 Mohammed’s flight, the Hegira, from Mecca to Medina began. Traditionally, the Islamic calendar began at sunset on this day.*VFR


    1662 The Royal Society of London received its charter. *VFR Its official foundation date is 28 November 1660, when a group of 12 met at Gresham College after a lecture by Christopher Wren, then the Gresham Professor of Astronomy, and decided to found 'a Colledge for the Promoting of Physico-Mathematicall Experimentall Learning'. This group included Wren himself, Robert Boyle, John Wilkins, Sir Robert Moray, and William, Viscount Brouncker.  In 1662 the Society was permitted by Royal Charter to publish and the first two books it produced were John Evelyn's Sylva and Micrographia by Robert Hooke. *Royal Society Web page







    1808 Thomas Jefferson writes to Augustin-François Silvestre French inventor and popularizer of science to thank him for sharing copies of " volumes of the Memoirs of the Agricultural Society of the Seine" and shares his ideas about the importance of the plough, including details of a mould board of his own design. "I shall with great pleasure attend to the construction and transmission to the Society of a plough with my mould board. This is the only part of that useful instrument to which I have paid any particular attention. But knowing how much the perfection of the plough must depend, 1st, on the line of traction; 2d, on the direction of the share; 3d, on the angle of the wing; 4th, on the form of the mould-board; " *Letters of Thomas Jefferson, http://www.let.rug.nl  



    The mould board is the part of the plough that receives the furrow slice from the share. It is responsible for lifting and turning the furrow slice.


    1828 The Board of Longitude is dissolved by act of Parliament. In the Parliamentary discussions prior to the act, John Crocker, First Secretary of the Admiralty,  argued that the Board was :

    "wholly occupied in reading the wild ravings of mad men, who fancied they had discovered perpetual motion and such like chimeras."


    1895 Rudolf Diesel applies for patent for an internal combustion engine in the US (patented Aug 9, 1898.) "My invention has reference to improvements in apparatus for regulating the fuel supply in slow-combustion motors" *Google.com


    1913 A window at Westminster Abbey, in memory of Lord Kelvin, was unveiled.*VFR (If someone has a better image of this window to offer, please send me a copy and I will replace this very small image.) 

    The memorial window to Lord Kelvin, subscribed for by engineers in Great Britain, Canada, and the United States, was dedicated at a special service in Westminster Abbey. The window is in the east bay of the nave on the north side. The light from it falls upon the graves of Kelvin and Isaac Newton, and immediately beneath it are the graves of Darwin and Herschel.




    1928 The first message for transmission by the Enigma was encoded.*VFR The first Enigma was invented by German engineer Arthur Scherbius at the end of World War I. This model and its variants were used commercially from the early 1920s, and adopted by military and government services of several countries — most notably by Nazi Germany before and during World War II. Several different Enigma models were produced, but the German military models are the ones most commonly discussed. *Wik

    Military Enigma machine, model "Enigma I", used during the late 1930s and during the war; displayed at Museo Nazionale Scienza e Tecnologia Leonardo da Vinci, Milan, Italy

    The Polish made an early contribution to the war effort starting almost a decade before the war. Their contribution to breaking the Enigma cipher was a foundational achievement in the history of cryptanalysis. In the early 1930s, a team of young Polish mathematicians—Marian Rejewski, Jerzy Różycki, and Henryk Zygalski—working for the Polish Cipher Bureau, made the first successful attempts to understand and decipher messages encoded with the German Enigma machine. Using mathematical techniques and intelligence obtained through French sources, Rejewski was able to reconstruct the internal wiring of the Enigma's rotors—a breakthrough that turned the abstract problem of codebreaking into a solvable equation. This approach marked a shift from traditional linguistic codebreaking to mathematical cryptanalysis.

    To keep up with evolving German procedures, the Poles developed mechanical tools to automate parts of the decryption process. Rejewski designed the bomba kryptologiczna, an electromechanical device that could help determine the machine's daily settings, while Zygalski created a system of perforated sheets—later known as Zygalski sheets—which exploited weaknesses in message encipherment protocols. In July 1939, with war imminent, the Polish team shared their methods, tools, and a working Enigma replica with British and French intelligence. This crucial handoff gave the Allies a vital head start, enabling the British work at Bletchley Park, including the famous Bombe designed by Alan Turing, to proceed much more rapidly. Though long underrecognized, the Polish mathematicians' early breakthroughs were essential to the eventual success in cracking Enigma and shortening World War II.






    BIRTHS


    1808 Sir Henry Cole (15 July 1808 – 18 April 1882) British industrial designer, museum director and writer who produced the first commercial Christmas card.* Cole played a pivotal role in the introduction of the Penny Post, the English postal system (assistant to Rowland Hill, 1837-40), influenced the expansion of railways, helped establish the Victoria and Albert Museum, contributed greatly to the success of London’s Great Exhibition of 1851, and promoted art and science education. In 1843, wishing to save much handwriting of seasonal correspondance, Cole introduced the world's first commercial Christmas card. He commissioned artist John Callcott Horsley to make the artwork for 1000 hand-coloured lithographs. (Individuals' homemade Christmas cards had existed earlier.)


    1848 Vilfredo Federico Damaso Pareto (15 July 1848 – 19 August 1923) born Wilfried Fritz Pareto, was an Italian engineer, sociologist, economist, and philosopher. He made several important contributions to economics, particularly in the study of income distribution and in the analysis of individuals' choices. "His legacy as an economist was profound. Partly because of him, the field evolved from a branch of moral philosophy as practiced by Adam Smith into a data intensive field of scientific research and mathematical equations. His books look more like modern economics than most other texts of that day: tables of statistics from across the world and ages, rows of integral signs and equations, intricate charts and graphs."He introduced the concept of Pareto efficiency and helped develop the field of microeconomics. He also was the first to discover that income follows a Pareto distribution, which is a power law probability distribution. The Pareto principle was named after him and built on observations of his such as that 80% of the land in Italy was owned by 20% of the population. He also contributed to the fields of sociology and mathematics.*Wik



    1865 Wilhelm Wirtinger (15 July 1865 – 15 January 1945) was an Austrian mathematician, working in complex analysis, geometry, algebra, number theory, Lie groups and knot theory. Wirtinger was greatly influenced by Felix Klein with whom he studied at the University of Berlin and the University of Göttingen. In 1907 the Royal Society of London awarded him the Sylvester Medal, for his contributions to the general theory of functions. *Wik





    1897 Letitia Chitty (15 July 1897 – 29 September 1982) was an English engineer who became a respected structural analytical engineer, achieving several firsts for women engineers, including becoming the first female fellow of the Royal Aeronautical Society and the second female recipient of the Telford Medal.
     She entered Newnham College, Cambridge in 1916, taking the first part of the Tripos. During World War I, as part of a British program to identify the best female mathematics graduates and current students, she was selected for war work with Alfred Pippard at the Admiralty Air Department at age 19. After the war she returned to her studies, changed subject to engineering, and graduated with a titular degree from Newnham College with first class honors in the Mechanical Sciences Tripos, 1921, the first woman to do so.
    Her early career focused on analyzing the stresses of airframes, airships and civil engineering structures, initially with the Admiralty Air Department and then, after graduating, at the Air Ministry with Richard Southwell and Alfred Pippard.
    Chitty moved to Imperial College in 1934 where she remained for the rest of her career, initially specialising in structural stresses in aircraft. During the 1930s, she was part of a group which analysed the crash of the airship R38, and published various Air Ministry papers on stresses and strains on airship structures. She was an early member of the Women's Engineering Society.
    In her will, she left a bequest to Imperial College, which named its Library reading room after her. Imperial College also presents a Letitia Chitty Centenary Memorial Prize, while Newnham College has presented a 'Letitia Chitty Award for Engineering'.




    1898 Mary Taylor Slow (15 July 1898 – 26 May 1984) was a British physicist who worked on the theory of radio waves and the application of differential equations to physics. She was the first woman to take up the study of radio as a profession.
    Mary Taylor was born in Sheffield, England. Both her parents were schoolteachers. She was educated at Pomona Street Elementary School in Sheffield and then Sheffield High School, from which she won a Clothworker's Scholarship to Girton College, Cambridge. She studied the Natural Sciences Tripos; in 1919 she was awarded the equivalent of a first-class BA degree, and in 1920 she graduated in mathematics and natural sciences.
    Taylor continued to study at Girton College under a series of research studentships. From 1922 to 1924 she was Assistant Lecturer in Mathematics at Girton. During this time she became interested in the theory of radio waves and started to conduct research under the guidance of Edward Appleton who was then assistant demonstrator in experimental physics at the Cavendish Laboratory in Cambridge.

    When Appleton left Cambridge to join King's College, London, Taylor moved from Cambridge to the University of Göttingen in Germany. Here she was awarded her PhD in 1926 for a thesis on aspects of electromagnetic waves that she wrote in German. Taylor was awarded a Yarrow Research Fellowship which enabled her to remain at Göttingen and continue her work on electromagnetic waves with Professor Richard Courant.

    In 1929 Taylor returned to the UK and took up a post as Scientific Officer at the Radio Research Station in Slough, Berkshire (part of the UK Department of Scientific and Industrial Research and the UK National Physics Laboratory, now the National Physical Laboratory). Here she continued to carry out research into the theory of electromagnetic waves, specializing in the magneto-ionic theory of radio wave propagation and in the application of differential equations to physics and radio. During this period she published two papers in the Proceedings of the Physical Society, both on aspects of the Appleton-Hartree Equation. Taylor was a member of the London Mathematical Society and the Cambridge Philosophical Society.






    1906 Adolph Andrei Pavlovich Yushkevich (15 July, 1906 – 17 July, 1993) was one of the leading historians of mathematics in the world. His doctorate was on Russian mathematics during the 18th century and he began publishing in 1929 the first of over 300 works on the history of mathematics. He contributed 21 articles to the Dictionary of Scientific Biography which are referenced in this Archive. This Archive also references over 50 articles by Yushkevich about a wide range of mathematicians from the earliest to modern times. Yushkevich was arguably the leading world authority on Euler and he was one of the leading authorities on medieval mathematics. *SAU



    1909 William Gemmell Cochran (15 July 1909, Rutherglen – 29 March 1980, Orleans, Massachusetts) Statistician. In 1934 R A Fisher left Rothamsted Experimental Station to accept the Galton chair at University College, London and Frank Yates became head at Rothamsted. Cochran was offered the vacant post but he had not finished his doctoral course at Cambridge. Yates later wrote:-
    ... it was a measure of good sense that he accepted my argument that a PhD, even from Cambridge, was little evidence of research ability, and that Cambridge had at that time little to teach him in statistics that could not be much better learnt from practical work in a research institute.
    Cochran accepted the post at Rothamsted where he worked for 5 years on experimental designs and sample survey techniques. During this time he worked closely with Yates. At this time he also had the chance to work with Fisher who was a frequent visitor at Rothamsted.
    Cochran visited Iowa Statistical Laboratory in 1938, then he accepted a statistics post there in 1939. His task was to develop the graduate programme in statistics within the Mathematics Department. In 1943 he joined Wilks research team at Princeton.
    At Princeton he was involved in war work examining probabilities of hits in naval warfare. By 1945 he was working on bombing raid strategies.
    He joined the newly created North Carolina Institute of Statistics in 1946, again to develop the graduate programme in statistics. From 1949 until 1957 he was at Johns Hopkins University in the chair of biostatistics. Here he was more involved in medical applications of statistics rather than the agricultural application he had studied earlier.
    From 1957 until he retired in 1976 Cochran was at Harvard. His initial task was to help set up a statistics department, something which he had a great deal of experience with by this time. He had almost become a professional at starting statistics within universities in the USA. *SAU



    1912 Tibor Gallai (born Tibor Grünwald, 15 July 1912 – 2 January 1992) was a Hungarian mathematician. He worked in combinatorics, especially in graph theory, and was a lifelong friend and collaborator of Paul Erdős. He was a student of Dénes Kőnig and an advisor of László Lovász. He was a corresponding member of the Hungarian Academy of Sciences (1991).

    The Edmonds–Gallai decomposition theorem, which was proved independently by Gallai and Jack Edmonds, describes finite graphs from the point of view of matchings. Gallai also proved, with Milgram, Dilworth's theorem in 1947, but as they hesitated to publish the result, Dilworth independently discovered and published it.

    Gallai was the first to prove the higher-dimensional version of van der Waerden's theorem.

    With Paul Erdős he gave a necessary and sufficient condition for a sequence to be the degree sequence of a graph, known as the Erdős–Gallai theorem.



    1922 Leon Max Lederman (July 15, 1922 - October 3, 2018 American physicist who, along with Melvin Schwartz and Jack Steinberger, received the Nobel Prize for Physics in1988 for their joint research and discovery (1960-62) of a new subatomic particle, the muon neutrino. Neutrinos are subatomic particles having no detectable mass and no electric charge, which travel at nearly the speed of light. The discovery of muon neutrinos, a new type of neutrino, was followed by discoveries by other scientists of a number of different "families" of subatomic particle. Together, they now form a standard model, a scheme that has been used to classify all known elementary particles. He was director of the Fermi National Accelerator Laboratory in Batavia, Ill.*TIS
    The Higgs Boson's media nickname "The God Particle" came from Lederman, who wrote a book he wanted titled "The Goddamn Particle", making fun at how hard it was to find. The publishers changed the title to "The God Particle" and the nickname stuck.



    1930 Steven Smale (July 15, 1930 - ) born in Flint, Michigan. He earned three degrees at the University of Michigan and now teaches at Berkeley. He has made significant contributions to topology (Fields Medal, 1966), dynamical systems, economics, and numerical analysis. This still leaves time for chess, go, sailing, collecting minerals, and lots of political activism. For an interview with this fa­cinating mathematician, see More Mathematical People (1990), edited by Donald J. Albers, G. L. Alexanderson and Constance Reid.*VFR



    1943 Jocelyn Bell Burnel(15 July 1943- ) British astronomer who discovered the first four pulsars. She was a Cambridge University graduate student, age 24, searching for quasars in 1967, when she noticed an unusual stellar radio signal - a rapid series of pulses repeating every 1.337 sec. This interstellar beacon was not man-made, so it was nicknamed in fun as LGM, for Little Green Men. In the next few months, Bell (her maiden name) found three more sources of radio pulses by careful scrutiny of hundreds of feet of pen-recorder paper. These represented a new class of celestial objects - pulsars - which astronomers eventually associated with superdense matter in the final stage of the evolution of massive stars. To date, hundreds more pulsars have been identified. *TIS

    80 periods of the pulsar CP 1919 stacked together, graphic originated by Howard D. Craft, Jr, 1970, reworked for Scientific American, July 1971 



    *Linda Hall Org



    1978  Caucher Birkar FRS,  born Fereydoun Derakhshani ( July ?, 1978) is a UK-based Iranian Kurdish and British mathematician (born in Iran) and a professor at Tsinghua University. He is also an Honorary Professor at the University of Nottingham. 

    Birkar is an important contributor to modern birational geometry. In 2010 he received the Leverhulme Prize in mathematics and statistics for his contributions to algebraic geometry, and in 2016, shared the AMS Moore Prize for the article "Existence of minimal models for varieties of log general type". He was awarded the Fields Medal in 2018, "for his proof of boundedness of Fano varieties and contributions to the minimal model program". In his office at the University, Birkar has two photographs of Alexander Grothendieck, his favorite mathematician, who like Birkar, was a refugee and Fields medalist.

    Birkar maintains strong ties to his Kurdish heritage and actively encourages Kurdish identity while also separating it from nationalism and politics. According to Birkar, his strong Kurdish identity is not a part of nationalism nor politics and he is not striving for such achievements. This can be a reflection of his name change to Caucher Birkar which roughly translates into ”the Migrating Mathematician”.

    Birkar is an important contributor to modern birational geometry. In 2010 he received the Leverhulme Prize in mathematics and statistics for his contributions to algebraic geometry, and in 2016, shared the AMS Moore Prize for the article "Existence of minimal models for varieties of log general type". He was awarded the Fields Medal in 2018, "for his proof of boundedness of Fano varieties and contributions to the minimal model program" In his office at the University, Birkar has two photographs of Alexander Grothendieck, his favorite mathematician, who like Birkar, was a refugee and Fields medalist.

    Birkar maintains strong ties to his Kurdish heritage and actively encourages Kurdish identity while also separating it from nationalism and politics. According to Birkar, his strong Kurdish identity is not a part of nationalism nor politics and he is not striving for such achievements. This can be a reflection of his name change to Caucher Birkar which roughly translates into ”the Migrating Mathematician”. *Wik






    DEATHS


    998 Abu'l-Wafa (10 June 940 – 15 July 998) was an Islamic astronomer and mathematician who wrote commentaries on the works of earlier mathematicians. He made astronomical observations and constructed accurate trigonometric tables.*SAU
    He made important innovations in spherical trigonometry, and his work on arithmetics for businessmen contains the first instance of using negative numbers in a medieval Islamic text.
    He is also credited of compiling tables of sines and tangents at 15' intervals. He also introduced the sec and cosec and studied the interrelations between the six trigonometric lines associated with an arc. His Almagest was widely read by medieval Arabic astronomers in the centuries after his death. He is known to have written several other books that have not survived. *Wik




    1841 Félix Savary (October 4, 1797, Paris - July 15, 1841 in Estagel) was a student at the École Polytechnique completing his studies in 1815. He then taught at the École, becoming a professor of astronomy and geodesy there in 1831. There he became a founder of studies into surveying and machines.
    Savary also served as librarian at the Bureau des Longitudes from 1823 to 1829. Then on 24 December 1832, in recognition of his achievements, he was elected to the Académie des Sciences.
    He worked on electromagnetism and electrodynamics, some work being done jointly with Ampère. In particular, on this topic, he wrote Mémoire sur l'application du calcul aux phenomènes élecro-dynamique (1823).
    Savary also developed a theorem (named after him) on the curvature of a roulette, the curve traced out by a point on a fixed curve which rolls on a second curve.
    He wrote on the rotation of magnets, studied the intensity of magnetism through an electrical discharge (1827), and applied the laws of gravity to determine the orbits of double stars in close orbit round each other (1827). In fact, on the topic of double stars, he published Mémoire sur les orbites des étoiles doubles (1827), and Sur la détermination des orbites que décrivent autour de leur centre de gravité deux étoiles très rapprochées l'une de l'autre (1827) in Connaissance des Temps. The star x Ursae Majoris is a double star and Savary demonstrated that the two stars move in elliptical orbits with the centre of gravity at the focus of the ellipses. Although this might appear to be a fairly simple consequence of Newton's law of gravitation, nevertheless it was important for it was the first verification of the laws for objects outside the solar system. This was the first verification of the universal nature of Newton's laws.*SAU


    1931 Ladislaus Josephowitsch Bortkiewic  (7 August 1868 – 15 July 1931)  studied law at St Petersburg, graduating in 1890 and then went on to study political economy and statistics for a year of postgraduate work. He studied at Strasbourg from 1891 to 1892, then at Göttingen under Lexis in 1892, going on to also study at Vienna and Leipzig. After submitting a dissertation, he was awarded a doctorate in 1893 from Göttingen.
    After lecturing in statistics and actuarial science from 1895 to 1897 as a privatdozent in Strasbourg he went to St Petersburg where he was a clerk in the Railway Office from 1897 until 1901. However, during this time he returned to academic life, teaching statistics from 1899 until December 1900 at the Alexandrowskii Lyceum. Then in 1901 he was appointed as an extraordinary professor of statistics at the University of Berlin. Bortkiewicz became an ordinary professor of statistics and political economy at the University of Berlin in 1920 and he spent the rest of his life there. An unfortunate argument with an Italian statistician Gini, who accused Bortkiewicz of plagiarism, led to an unhappy episode near the end of Bortkiewicz's life.
    Bortkiewicz worked on mathematical statistics and applications to actuarial science and political economy. His work on actuarial science was largely concerned with mortality tables. He examined life expectancy in an increasing population and showed in 1893, contrary to what had previously been believed, that life expectancy in such a population could only be computed from mortality tables and was not a function of the observed birth rate and death rate. He published on mortality rates again in publication of 1904 and 1911 where he examined methods to compare mortality rates.
    Good argues that the Poisson distribution should have been named the von Bortkiewicz distribution. Bortkiewicz was interested in the law of small numbers and he used the divergence coefficient Q, deducing its expectation and standard deviation. He published a work The Law of Small Numbers in 1898. In this he was the first to note that events with low frequency in a large population followed a Poisson distribution even when the probabilities of the events varied.Other areas to which Bortkiewicz applied his statistical methods include radioactivity (1913), order statistics, and applications to legal studies. *SAU




    1961 Nina Karlova Bari (November 19, 1901, Moscow – July 15, 1961, Moscow) was hit by a train in Moscow Metro. It is unclear whether it was an accident or a suicide brought on by despondency over the death of Nikolai Nikolaevich Luzin (1883–1950), her teacher and reported lover.*VFR  

    She was a Soviet mathematician known for her work on trigonometric series. She is also well-known for two textbooks, Higher Algebra and The Theory of Series.

    Bari applied for and received the only paid research fellowship awarded by the newly created Research Institute of Mathematics and Mechanics. As a student, Bari was drawn to an elite group nicknamed the Luzitania—an informal academic and social organization. She studied trigonometric series and functions under the tutelage of Nikolai Luzin, becoming one of his star students. She presented the main result of her research to the Moscow Mathematical Society in 1922—the first woman to address the society. *Wik

    At some point itseems she became Luzin's lover. *PB notes




    1965 Dudley Weldon Woodard (October 3, 1881 – July 1  {or 15?}, 1965) was a Galveston-born American mathematician and professor, and the second African-American to earn a PhD in mathematics; the first was Woodard's mentor Elbert Frank Cox, who earned a PhD from Cornell in 1925).

    He received his B.A. degree from Wilberforce University in Ohio (1903), his B.S. degree (1906) and M.Sc. degree (1907) at the University of Chicago. He taught collegiate mathematics in Tuskegee for many years, until finally he earned his PhD at the University of Pennsylvania (1928). His doctoral thesis was entitled, On Two-Dimensional Analysis Situs with Special Reference to the Jordan Curve Theorem, and was advised by John R. Kline.

    During his lifetime, he published three papers. The second of these, The Characterization of the Closed N-Cell in Fundamenta Mathematicae, 13 (1929), is, according to Scott Williams, Professor of Mathematics at the State University of New York-Buffalo, the first paper published in an accredited mathematics journal by an African American. He also published a study for the Committee of twelve for the advancement of the interests of the Negro race on Jackson, Mississippi in 1909, a textbook, Practical Arithmetic (1911), and an article on geometry teaching at Tuskegee in 1913.

    Woodard was a respected mathematician, professor and mentor to his students at Howard University in Washington DC, where he established the masters program in mathematics. One of his best known students was William Waldron Schieffelin Claytor, who later took his PhD at the University of Pennsylvania (1933), also under Woodard's former advisor, John R. Kline.

    Woodard retired in 1947, after having become chairman of the mathematics department. He died on July 1, 1965, at his home in Cleveland, Ohio, aged 83.




    1995 Paul Joseph Kelly (June 26, 1915 – July 15, 1995) was an American mathematician who worked in geometry and graph theory. Kelly was born in Riverside, California. He earned bachelor's and master's degrees from the University of California, Los Angeles before moving to the University of Wisconsin–Madison for doctoral studies; he earned his Ph.D. in 1942 with a dissertation concerning geometric transformations under the supervision of Stanislaw Ulam.
    Kelly is known for posing the reconstruction conjecture with his advisor Ulam, which states that every graph is uniquely determined by the ensemble of subgraphs formed by deleting one vertex in each possible way. He also proved a special case of this conjecture, for trees.

    He is the coauthor of three textbooks: Projective geometry and projective metrics (1953, with Herbert Busemann), Geometry and convexity: A study in mathematical methods (1979, with Max L. Weiss), and The non-Euclidean, hyperbolic plane: Its structure and consistency (1981, with Gordon Matthews).






    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
    *WM = Women of Mathematics, Grinstein & Campbell