**I believe that we do not know anything for certain,**

**but everything probably.**

~ Christiaan Huygens

The 117th day of the year; 117 can be written as the difference of prime squares (11

^{2}- 2

^{2}) or prime cubes (5

^{3}- 2

^{3}). *Prime Curios (Can you find another number which can be expressed as both the difference of squared primes and cubed primes?)

117 is the smallest possible length for the longest side of a Heronian tetrahedron (one whose sides are all integers, and all surface areas and volume are rational). The other edges are 51, 52, 53, 80, & 84. (Are the areas / volume integral?)

*Mathworld.Wolfram |

**EVENTS**

**1657 Christiaan Huygens**published De ratiociniis in ludo aleae. *VFR [Download of English version printed in London in pdf]

**1740**The French Academie des Sciences announced that their prize on the ebb and ﬂow of the tides would be shared between Leonhard Euler, Daniel Bernoulli, Antoine Cavalleri, one of the last of the Cartesians, and Colin Maclaurin, then Professor of Mathematics at the University of Edinburgh. [Niccol´o Guiciardini, The Development of Newtonian Calculus in Britain 1700–1800 (1989), p. 69.] *VFR

**1783**In a letter to A. M. Lorgna, Gian Francesco Malfatti gave the polar equation concerning the squaring of the circle. [DSB 9, 55] Does this refer to the polar equation of the spiral of Archimedes, r = aθ? *VFR

In 1871, the American Museum of Natural History opened to the public in New York City. With a series of exhibits, the Museum's collection Went on view for the first time in the Central Park Arsenal, the Museum's original home, on the eastern side of Central Park. The museum began from the efforts of Albert Smith Bickmore, one-time student of Harvard zoologist Louis Agassiz, who was successful in his proposal to create a natural history museum in Central Park, New York City, with the support of William E. Dodge, Jr., Theodore Roosevelt, Sr., Joseph Choate, and J. Pierpont Morgan. The Governor of New York, John Thompson Hoffman, signed a bill officially creating the American Museum of Natural History on 6 Apr 1869. *TIS

1865 King George V of Hanover visited Gottingen and ordered a commemorative plate placed at the room in which Gauss had died ten years before.

In 1895, Professor Charles F. Marvin, a future chief of the Weather Bureau, began experimenting with kites for routine use in the Bureau. In 1896 he perfected his kite meteorograph, an instrument capable of measuring and recording temperature, pressure and humidity. These measurements were recorded by pens tracings on paper, or on a smoked copper sheet, which was attached to a clock rotated drum. i

n 1898, the first Weather Bureau kite was launched from Topeka, Kansas, and by the end of the year, 16 additional kite stations were attempting daily, early morning, simultaneous observations. The kites were large "box types" with dimensions of 8 feet long, 7 feet wide and 3 feet high. As many as seven kites would be attached to the kite wire during and observation. These kites were placed at regular intervals with the second 1500 feet behind the first, the third 2000 feet behind the second and from there on a spacing of 2500 feet.*TIS

**1961**Patent issued for multilayer circuit boards. Hazeltyne, a US firm, patented hole technology and its use in multi-layer printed circuit board assemblies. The result was that component density increased, and the newly close-spaced electrical paths changed the design of printed circuit board assemblies dramatically.

**1962**The Netherlands issued a stamp showing Christiaan Huygens’ Pendulum

Clock as pictured by van Ceulen. [Scott #B365] *VFR

1994 U.S. Companies Get Aid From Government The Clinton administration unveils a multimillion-dollar program to aid U.S. companies that make flat-panel display screens as part of an effort to help the industry stay afloat in light of Japanese domination of 95 percent of the industry. The funding comes partly from the Defense Department, for use of flat screens on military equipment. The flat-panel display market had previously been limited to laptop computers. *CHM

2002 The last successful reception of telemetry was received from Pioneer 10 on April 27, 2002; subsequent signals were barely strong enough to detect, and provided no usable data. Pioneer 10 was launched in 1972 . Pioneer 10 crossed the orbit of Saturn in 1976 and the orbit of Uranus in 1979.

On June 13, 1983, Pioneer 10 crossed the orbit of Neptune, the outermost planet at the time, and so became the first man-made object to leave the proximity of the major planets of the solar system. The final, very weak signal from Pioneer 10 was received on January 23, 2003 when it was 12 billion kilometers (80 AU) from Earth. *Wik

**BIRTHS**

**1791 Samuel Finley Breese Morse**(27 Apr 1791; 2 Apr 1872 at age 81) was an American artist and inventor who is famous for developing the Morse Code (1838) and independently perfecting an electric telegraph (1832-35). He spent the first part of his life as a portrait artist, and did not turn to science until 1832, when he was past his 40th birthday. He was returning to America from a tour of Europe, when he met Charles T. Jackson on the boat, who inspired him about newly discovered electromagnets. From that point, Morse worked to develop apparatus for electrical communications. Backed by Congress, he erected a line spanning 40 miles between Baltimore, Maryland and Washington D.C. which had its first trial on 23 May 1843. It was ready for public use on 1 Apr 1845. *TIS

**1837 Paul Albert Gordan**,(27 April 1837 – 21 December 1912) king of the invariant theorists, (died: 1912). He found simpler proofs that π and e are transcendental. Emmy Noether, the ﬁrst woman to get a doctorate in Germany, was his student. *VFR

**1843 Felix Muller**He compiled the earliest mathematical calendar (that I know of)*VFR. Interests were in the history of mathematical terminology. His advisors were Weierstrass and Kummer.

1875 (6th duke) (Louis-César-Victor-) Maurice de Broglie (27 Apr 1875; died 14 Jul 1960 at age 85.) a French physicist who made many contributions to the study of X rays. While in the navy (1895-1908), he first distinguished himself by installing the first French shipboard wireless. From 1912, his chief interest was X-ray spectroscopy. His “method of the rotating crystal” was an application of Bragg's “focussing effect” to eliminate spurious spectral lines. De Broglie discovered the third L absorption edge (1916), which led to the exploration of “corpuscular spectra.” During 1921-22, he worked with his brother Louis to refine Bohr's specification of the substructure of the various atomic shells. He also did pioneer work in nuclear physics and cosmic radiation.*TIS

1920 Mark Alexandrovich Krasnosel'skii (April 27, 1920, Starokostiantyniv – February 13, 1997, Moscow) was a Soviet, Russian and Ukrainian mathematician renowned for his work on nonlinear functional analysis and its applications. *Wik

**DEATHS**

**1936 Karl Pearson**, (27 March 1857 in London, England - 27 April 1936 in Coldharbour, Surrey, England) English mathematician, one of the founders of modern statistics. Pearson's lectures as professor of geometry evolved into The Grammar of Science (1892), his most widely read book and a classic in the philosophy of science. Stimulated by the evolutionary writings of Francis Galton and a personal friendship with Walter F.R. Weldon, Pearson became immersed in the problem of applying statistics to biological problems of heredity and evolution. The methods he developed are essential to every serious application of statistics. From 1893 to 1912 he wrote a series of 18 papers entitled Mathematical Contributions to the Theory of Evolution, which contained much of his most valuable work, including the chi-square test of statistical significance. *TIS l There is a plaque in the church at Crambe in No. Yorkshire where he was born and many of his family are buried.

**1978 Guido Stampacchia**(March 26, 1922 - April 27, 1978) was a 20th century mathematician. Stampacchia was active in research and teaching throughout his career. He made key contributions to a number of fields, including calculus of variation and differential equations. In 1967 Stampacchia was elected President of the Unione Matematica Italiana. It was about this time that his research efforts shifted toward the emerging field of variational inequalities, which he modeled after boundary value problems for partial differential equations.

Stampacchia accepted the position of Professor Mathematical Analysis at the University of Rome in 1968 and returned to Pisa in 1970. He suffered a serious heart attack in early 1978 and died of heart arrest on April 27 of that year *Wik

1999 Rolf William Landauer (4 Feb 1927; 27 Apr 1999) German-born American physicist known for his formulation of Landauer's principle concerning the energy used during a computer's operation. Whenever the machine is resetting for another computation, bits are flushed from the computer's memory, and in that electronic operation, a certain amount of energy is lost. Thus, when information is erased, there is an inevitable "thermodynamic cost of forgetting," which governs the development of more energy-efficient computers. While engineers dealt with practical limitations of compacting ever more circuitry onto tiny chips, Landauer considered the theoretical limit, that if technology improved indefinitely, how soon will it run into the insuperable barriers set by nature?*TIS

**1999 Mark David Weiser**(23 Jul 1952, 27 Apr 1999 at age 46) American computer scientist and visionary who was the chief technology officer at XEROX PARC, and is remembered for developed the pioneering idea for what he referred to as “ubiquitous computing.” He coined that term in 1988 to describe a future in which personal computers will be replaced with tiny computers embedded in everyday “smart” devices (everyday items such as coffeepots and copy machines) and their connection via a network. He said, “First were mainframes, each shared by lots of people. Now we are in the personal computing era, person and machine staring uneasily at each other across the desktop. Next comes ubiquitous computing, or the age of calm technology, when technology recedes into the background of our lives.” He died at age 46, only six weeks after being diagnosed as having gastric cancer. *TIS

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