**All truths are easy to understand once they are discovered;**

**the point is to discover them.**

~Galileo Galilei

The 163rd day of the year; \( e^{\pi*\sqrt{163}} \) is an integer. Ok, not quite, see the bottom of the blog for details. *Prime Curios

Colin Beveridge @icecolbeveridge pointed out that \( (2+\sqrt{3})^{163} \) is also very, very close to an integer. (but it is very large,greater than 10

^{93}, and was not, to my knowledge, ever the source of an April fools joke.)

163 is conjectured to be the largest prime that can be represented uniquely as the sum of three squares /( 163 = 1^2 + 9^2 + 9^2 /).

Most students know that the real numbers can be uniquely factored. . Some other fields can be uniquely factored as well, for instance, the complex field a+bi where i represents the square root of -1 is such a field. In 1801, Gauss conjectured that there were only nine integers k such that \(a + b\sqrt{-k} \) is a uniquely factorable field. The largest of these integers is 163. Today they are called Heegner numbers after a proof by Kurt Heegner in 1952.

**EVENTS**

**1644**Florentine scientist, Evangelista Torricelli described in a letter (to Michelangelo Ricci) the invention of a barometer, or "Torricellian tube.

"Many have said that a vacuum does not exist, others that it does exist in spite of the repugnance of nature and with difficulty; I know of no one who has said that it exists without difficulty and without a resistance from nature. I argued thus: If there can be found a manifest cause from which the resistance can be derived which is felt if we try to make a vacuum, it seems to me foolish to try to attribute to vacuum those operations which follow evidently from some other cause; and so by making some very easy calculations, I found that the cause assigned by me (that is, the weight of the atmosphere) ought by itself alone to offer a greater resistance than it does when we try to produce a vacuum."

"We live submerged at the bottom of an ocean of air.",

**1742**, Benjamin Franklin invented the Franklin stove. The wood fuel burns on an iron surface over a cold air duct which heats air which then passes through baffles in the back wall. The heated air is released through vents on each side of the stove. Rather than patent it, he chose to write about it in a book so that others could freely copy his design. As he wrote, "That as we enjoy great Advantages from the Inventions of others, we should be glad of an Opportunity to serve others by any Invention of ours, and this we should do freely and generously."*TIS

collections.rmg.co.uk |

**1795**The Board of Longitude awards a 200 pound payment to Ralph Walker for his invention of a compass/sundial combination. "Comparing this reading with the direction in which the compass needle was pointing gave the magnetic variation. This could, in theory, be used to discover the longitude, by finding where supposed ‘magnetic meridians’ intersected with the observed latitude....Nevil Maskelyne didn’t think it was an effective longitude method" *kmcalpine, Royal Museum Greenwich blog

A letter with the directions for the instruments use is here, and the letter from the board to authorize the payment is here. (with HT to Richard Dunn@Lordoflongitude)

**1929**

Walt Disney files a trademark application for the image of Mickey Mouse with the United States Patent Office.

**1955**France issued a postage stamp with a portrait of

Pierre Simon de Laplace (1749–1827)

**BIRTHS**

**1656 Charles René Reyneau**(11 June 1656 in Brissac, Maine-et-Loire, France - 24 Feb 1728 in Paris, France) was a French mathematician who published an influential textbook on the newly invented calculus.*SAU (He) "undertook to reduce into one body, for the use of his scholars, the principal theories scattered here and there in Newton, Descartes, Leibnitz, Bernoulli, the Leipsic Acts, the Memoirs of the Paris Academy, and in other works; treasures which by being so widely dispersed, proved much less useful than they otherwise might have been. The fruit of this undertaking, was his “Analyse Demontree,” or Analysis Demonstrated, which he published in 1708, 2 vols. 4to. He gave it the name of “Analysis Demonstrated,” because he demonstrates in it several methods which had not been handled by the authors of them, with sufficient perspicuity and exactness. The book was so well approved, that it soon became a maxim, at least in France, that to follow him was the best, if not the only way, to make any extraordinary progress in the mathematics and he was considered as the first master, as the Euclid of the sublime geometry." (From the 1812 Chalmer's Biography, vol. 26, p. 151)

**1687 Maurice Paul Auguste Charles Fabry**(11 June 1867, Marseille – 11 December 1945, Paris) was a French physicist who graduated from the École Polytechnique in Paris.

Together with Henri Buisson, he discovered the ozone layer in 1913. In optics, he discovered an explanation for the phenomenon of interference fringes. Together with his colleague Alfred Pérot he invented the Fabry–Pérot interferometer.

In 1921, he was appointed Professor of General Physics at the Sorbonne and the first director of the new Institute of Optics. He was the first general director of the Institut d'optique théorique et appliquée and director of "grande école" École supérieure d'optique (SupOptique).

During his career Fabry published 197 scientific papers, 14 books, and over 100 popular articles. For his important scientific achievements he received the Rumford Medal from the Royal Society of London in 1918. In the United States his work was recognized by the Henry Draper Medal from the National Academy of Sciences (1919) and the Franklin Medal from the Franklin Institute (1921). In 1927 he was elected to the French Academy of Sciences. *Wik

**1723 Johann Georg Palitzsch**(June 11, 1723 – February 21, 1788) was born. As a German farmer and amateur astronomer from the village of Prohlis near Dresden, he would observe a comet on Christmas day in 1758 and confirm one of the most significant scientific theories in history. See the full story of his Christmas/birthday observation from Thony Christie.

**1862 Lothar Heffter**(June 11th 1862 in Koszalin , January 1 1962 in Freiburg )At the age of 99 he published the second edition of his Begr¨undung der Funktionentheorie. *VFR He did research in the theory of linear differential equations , the complex analysis and analytic geometry and worked on the four-color problem. Lazarus Fuchs was his teacher. His main concern was the popularization of mathematics.

**1881 Hilda Phoebe Hudson**(June 11, 1881 Cambridge – November 26, 1965 London) was an English mathematician who worked on algebraic geometry, in particular on Cremona transformations.

Educated at Newnham College, University of Cambridge, after a year studying at the University of Berlin she returned to Newnham as lecturer in mathematics and later Associate Research Fellow. She was also awarded MA and ScD degrees by Trinity College, Dublin. Most of Hudson's research was in the area of pure mathematics concerned with surfaces and plane curves, her special interest was in cremona transformation. Her monograph Ruler and Compasses was well-received as "a welcome addition to the literature on the boundary between elementary and advanced mathematics". In 1917 she joined an Air Ministry subdivision undertaking aeronautical engineering research, where she applied pioneering work on the application of mathematical modelling to aircraft design for which she was appointed OBE in 1919. As a distinguished mathematician she was one of the few women of her time to serve on the council of the London Mathematical Society. *Wik

**1886 David Barnard Steinman**(June 11, 1886 - August 21, 1960) Designer of the BIG MAC Bridge between the Upper and Lower Peninsulas of Michigan (

*top*). American engineer whose studies of airflow and wind velocity helped make possible the design of aerodynamically stable bridges. Steinman's thesis for his Ph.D. from Colombia University (1911) was published as "The Design of the Henry Hudson Memorial Bridge as a Steel Arch, and more than 20 years later he built the bridge he had planned over the Harlem River. Steinman designed more than 400 bridges, for instance Sidney Harbor Bridge in Australia, Mackinac Straits Bridge, Carquinez Strait Bridge, San Francisco (1937), Saint Johns Bridge, Portland, Ore, Deer Isle Bridge, Maine, Mount Hope Bridge, Rhode Island. *TIS

**1910 Jacques-Yves Cousteau**(11 June 1910 – 25 June 1997) French naval officer, oceanographer, marine biologist and ocean explorer, known for his extensive underseas investigations. He was co-inventor of the aqualung which made SCUBA diving possible (1943). Cousteau the developed the Conshelf series of manned habitats, the Diving Saucer, a process of underwater television and numerous other platforms and specialized instruments of ocean science. In 1945 he founded the French Navy's Undersea Research Group. He modified a WWII wooden hull minesweeper into the research vesselCalypso, in 1950. An observation dome added to the foot of Calypso's bow was found to increase the ship's stability, speed and fuel efficiency. *TIS For whom my oldest son is named.

1914 Rufus Philip Isaacs (11 June 1914 in New York City, New York -18 January 1981 in Baltimore) was a game theorist especially prominent in the 1950s and 1960s with his work on differential games.

He worked for the RAND Corporation from 1948 until winter 1954/1955. His investigation stemmed from classic pursuit-evasion type zero-sum dynamic two player games such as the Princess and monster game. In 1942, He married Rose Barcov, and they had two daughters.

His work in pure mathematics included working with monodiffric functions, fractional-order mappings, graph theory, analytic functions, and number theory. In graph theory he constructed the first two infinite families of snarks. In applied mathematics, he worked with aerodynamics, elasticity, optimization, and differential games, which he is most known for. He received his bachelors from MIT in 1936, and received his MA and PhD from Columbia University in 1942 and 1943 respectively. His first post after the war ended was at Notre Dame, but he left in 1947 due to salary issues. While at RAND, much of his work was classified, and thus remained unknown until the publication of his classic text on differential games a decade after leaving RAND. His career after RAND was spent largely in the defense and avionics industries. While at RAND, he worked with researchers including Richard E. Bellman, Leonard D. Berkovitz, David H. Blackwell, John M. Danskin, Melvin Dresher, Wendell H. Fleming, Irving L. Glicksberg, Oliver A. Gross, Samuel Karlin, John W. Milnor, John F. Nash, and Lloyd S. Shapley. His work has significant influence on mathematical optimization including fundamental concepts such as dynamic programming (Richard E. Bellman) and the Pontryagin maximum principle (Breitner 2005) which are widely used in economics and many other fields. *Wik

**1921 Rodney Hill FRS**(11 June 1921 – 2 February 2011) was an applied mathematician and a former Professor of Mechanics of Solids at Gonville and Caius College, Cambridge.

In 1953 he was appointed Professor of Applied Mathematics at Nottingham University. His 1950 The Mathematical Theory of Plasticity forms the foundation of plasticity theory. Hill is widely regarded as among the foremost contributors to the foundations of solid mechanics over the second half of the 20th century. His early work was central to founding the mathematical theory of plasticity. This deep interest led eventually to general studies of uniqueness and stability in nonlinear continuum mechanics, work which has had a profound influence on the field of solid mechanics—theoretical, computational and experimental alike—over the past decades. Hill was the founding editor of the Journal of the Mechanics and Physics of Solids, still among the principal journals in the field.

His work is recognized worldwide for its concise style of presentation and exemplary standards of scholarship. Publisher Elsevier, in collaboration with IUTAM, established a quadrennial award in the field of solid mechanics, known as the Rodney Hill Prize, first presented at ICTAM in Adelaide in August 2008. The prize consists of a plaque and a cheque for US$25,000. Its first recipient is Michael Ortiz, for his contribution to nonconvex plasticity and deformation microstructures (California Institute of Technology, USA).

He won the Royal Medal in 1993 for his contribution to the theoretical mechanics of soil and the plasticity of solids and was elected a Fellow of the Royal Society in 1961. He was awarded an Honorary Degree (Doctor of Science) by the University of Bath in 1978. *Wik

**1937 David Bryant Mumford**(11 June 1937- ) born in Worth, Sussex, England. In 1974 he won a Fields Medal for his work on “problems of the existence and structure of varieties of moduli, varieties whose points parameterize isomorhphism clases of some type of geometric object.” *VFR In the 1980s he turned to applied mathematics with the question "Is there a mathematical approach to understanding thought and the brain?" This is part of "Pattern Theory," as introduced by Ulf Grenander in the 70's to give a theoretical setting for a large number of related ideas, techniques and results from fields such as computer vision, speech recognition, image and acoustic signal processing, pattern recognition and its statistical side, neural nets and parts of artificial intelligence. *TIS

**DEATHS**

**1292 Roger Bacon**(Ilchester, Somersetshire, about 1214 - Oxford,

*perhaps*11 June, 1294) English scholar who was one of the first to propose mathematics and experimentation as appropriate methods of science. He studied mathematics, astronomy, optics, alchemy, and languages. He elucidated the principles of refraction, reflection, and spherical aberration, and described spectacles, which soon thereafter came into use. He developed many mathematical results concerning lenses, proposed mechanically propelled ships, carriages, and flying machines, and used a camera obscura to observe eclipses of the Sun. Bacon was the first European give a detailed description of the process of making gunpowder.*TIS

**1895 Daniel Kirkwood**(September 27, 1814 - June 11, 1895) American mathematician and astronomer who noted in about 1860 that there were several zones of low density in the minor-planet population. These gaps in the distribution of asteroid distances from the Sun are now known as Kirkwood gaps. He explained the gaps as resulting from perturbations by Jupiter. An object that revolved in one of the gaps would be disturbed regularly by the planet's gravitational pull and eventually would be moved to another orbit. Thus gaps appeared in the distribution of asteroids where the orbital period of any small body present would be a simple fraction of that of Jupiter. Kirwood showed that a similar effect accounted for gaps in Saturns rings.*TIS

1903 Nikolai Vasilievich Bugaev (September 14, 1837 – June 11, 1903) was a prominent Russian mathematician, the father of Andrei Bely.

Bugaev was born in Georgia, Russian Empire into a somewhat unstable family (his father was an army doctor), and at the age of ten young Nikolai was sent to Moscow to find his own means of obtaining an education. He succeeded, graduating in 1859 from Moscow University, where he majored in mathematics and physics. He went on to study engineering, but in 1863 wrote a Master's thesis on the convergence of infinite series. This document was sufficiently impressive to win him a place studying under Karl Weierstrass and Ernst Kummer in Berlin. He also spent some time in Paris studying under Joseph Liouville. He earned his doctoral degree in 1866 and returned to Moscow, where he taught for the remainder of his career. Some of his most influential papers offered proofs of previously unproven assertions of Liouville, but his most original work centered around the development of formal analogies between arithmetic and analytic operations. *Wik

**1931 Franklin H(enry) Giddings**(March 23, 1855 – June 11, 1931) American sociologist, one of the first in the United States to turn sociology from a branch of philosophy into a research science dependent on statistics. He was noted for his doctrine of the "consciousness of kind," which he derived from Adam Smith's conception of "sympathy," or shared moral reactions. His explanation of social phenomena was based this doctrine - his theory that each person has an innate sense of belonging to particular social groups. He encouraged statistical studies in sociology. *TIS

**1934 Friedrich Wilhelm Franz Meyer**(2 Sept 1856 in Magdeburg, Germany - 11 June 1934 in Königsberg, Germany (now Kaliningrad, Russia) studied algebraic geometry, algebraic curves and invariant theory. *SAU

*** Actually, \( e^{\pi*\sqrt{163}} \) is approximately 262537412640768743.9999999999992

In the April 1975 issue of Scientific American, Martin Gardner wrote (jokingly) that Ramanujan's constant (e^(pi*sqrt(163))) is an integer. The name "Ramanujan's constant" was actually coined by Simon Plouffe and derives from the above April Fool's joke played by Gardner. The French mathematician Charles Hermite (1822-1901) observed this property of 163 long before Ramanujan's work on these so-called "almost integers."

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