**The more I see of men, the better I like my dog**.

The 170th day of the year; the start of a record-breaking run of consecutive integers (170-176) with an odd number of prime factors.

170 is the smallest number that can be written as the sum of the squares of 2 distinct primes, where each of these primes is the square of a prime added to another prime (170 = (2

^{2}+ 3)

^{2}+ (3

^{2}+ 2)

^{2}).

*Prime Curios

170 is the largest integer for which its factorial can be stored in double-precision floating-point format. This is probably why it is also the largest factorial that Google's built-in calculator will calculate, returning the answer as 170! = 7.25741562 × 10

^{306}. (For 171! it returns "infinity".)

170 is the smallest number n for which phi(n)(the number of integers relatively prime to 170=64=8

^{2}) and sigma(n) (the sum of the divisors of 170=324=18

^{2}) are both square.

In

**240 BC**, Eratosthenes, a Greek astronomer and mathematician, estimated the circumference of the earth. As the director of the great library of Alexandria, he read in a papyrus book that in Syene, approaching noon on the summer solstice, the longest day of the year, shadows of temple columns grew shorter. At noon, they were gone. The sun was directly overhead. However, a stick in Alexandria, far to the north, could cast a pronounced shadow. Thus, he realized that the surface of the Earth could not be flat. It must be curved. Not only that, but the greater the curvature, the greater the difference in the shadow lengths. By measurement on the ground and application of geometry, he calculated the circumference of the earth. *TIS

**325**The early Christian church opened the council of Nicaea, which decided the rules for computing the date of Easter: The ﬁrst Sunday after the ﬁrst full moon on or after the vernal equinox *VFR

**1934**Jerzy Neyman's paper before the Royal Statistical Society entitled "On the Two Different Aspects of the Representative Method: The Method of Stratified Sampling and the Method of Purposive Selection. This paper was the one first presenting the concept of a "confidence interval" (interval estimate). *David Bee

**1934**1st motion picture of the solar surface was made using the McMath-Hulbert Spectroheliokinematograph :

K8MHO is the club radio station for the McMath-Hulbert Astronomical Society. The station is housed in the McGregor administration building of the McMath-Hulbert Solar Observatory which at one time was the second largest solar observatory in the world. The station is currently manned by Tom Hagen, NE9Y, and Dave Benham, K8TRF. Members of this radio club have a mutual interest in astronomy, ham radio and the preservation of the McMath-Hulbert Solar Observatory.

The McMath-Hulbert Solar Observatory was founded in 1929 by Francis McMath, his son Robert McMath and Henry Hulbert, neighbors who just had a mutual interest in astronomy. The first tower at this site was built with a 16 foot dome in 1930 and originally had a 10.5” equatorial telescope. As they gained more interest in observing the sun, this building became more exclusively devoted to solar observing. On June 19, 1934, they released the first ever motion picture film of the surface of the sun. *QRZ.Com with hat tip to David Dickinson @Astroguyz

**In 1963**, Soviet cosmonaut Valentina Tereshkova returned to Earth after spending nearly three days as the first woman in space. She had been interested in parachute jumping when she was young, and that expertise was one of the reasons she was picked for the cosmonaut program. She became the first person to be recruited without experience as a test pilot. On 16 Jun 1963, Tereshkova was launched into space aboard

*Vostok 6,*and became the first woman to travel in space. Her radio name was "Chaika," Russian for "seagull." Her flight made 48 orbits of Earth. Tereshkova never made a second trip into space. She became an important member of the Communist Party and a representative of the Soviet government.*TIS

**BIRTHS**

**1623 Blaise Pascal**( 19 June 1623 – 19 August 1662) born in Ferrand, Auvergne, France. He laid the foundation for the modern theory of probabilities. In hydrodynamics he formulated what came to be known as Pascal's law of pressure, and invented the syringe and hydraulic press. Pascal invented the first digital calculator to help his father with his work collecting taxes. He worked on it for three years (1642-45). The device, called the Pascaline, resembled a mechanical calculator of the 1940s. This, almost certainly, makes Pascal the second person to invent a mechanical calculator for Schickard had manufactured one in 1624. He died at the young age of 39 having been sickly and physically weak through life. Autopsy showed he had been born with a deformed skull.*TIS

**1669**

**Leonty Magnitsky**(June 9, 1669, Ostashkov – October 19, 1739, Moscow) was a Russian teacher who wrote the first guide to mathematics published in Russia.*SAU

**1771 Joseph Gergonne**born. (19 June 1771 Nancy, France—4 May 1859 Montpellier, France) He came under the influence of Gaspard Monge, the Director of the new École Polytechnique in Paris. In 1810, in response to difficulties he encountered in trying to publish his work, Gergonne founded his own mathematics journal, officially named the

*Annales de mathématiques pures et appliquées*but generally referred to as the

*Annales de Gergonne*. The most common subject of articles in his journal was geometry, Gergonne's specialty. Over a period of 22 years, the

*Annales de Gergonne*published about 200 articles by Gergonne himself, and other articles by many distinguished mathematicians, including Poncelet, Servois, Bobillier, Steiner, Plücker, Chasles, Brianchon, Dupin, Lamé, even Galois.

Gergonne was appointed to the chair of astronomy at the University of Montpellier in 1816. In 1830, he was appointed Rector of the University of Montpellier, at which time he ceased publishing his journal. He retired in 1844.

Gergonne was the first mathematician to employ the word polar. In a series of papers beginning in 1810, he discovered the principle of duality in projective geometry, by noticing that every theorem in the plane connecting points and lines corresponds to another theorem in which points and lines are interchanged, provided that the theorem embodied no metrical notions. In 1816, he devised an elegant solution to the problem of Apollonius: find a circle which touches three given circles.

In 1813, Gergonne wrote the prize-winning essay for the Bordeaux Academy,

*Methods of synthesis and analysis in mathematics*, unpublished to this day and known only via a summary. The essay is very revealing of Gergonne's philosophical ideas. He called for the abandonment of the words analysis and synthesis, claiming they lacked clear meanings. Surprisingly for a geometer, he suggested that algebra is more important than geometry, at a time when algebra consisted almost entirely of the elementary algebra of the real field. He predicted that one day quasi-mechanical methods would be used to discover new results.

In 1815, Gergonne wrote the first paper on the optimal design of experiments for polynomial regression. According to S. M. Stigler, Gergonne is the pioneer of optimal design as well as response surface methodology.

**1846 Antonio Abetti**(19 Jun 1846, 20 Feb 1928 at age 81) Italian astronomer who was an authority on minor planets. At first a civil engineer, he became an astronomer at the University of Padua (1868-93), with an interest in positional astronomy and made many observations of small planets, comets and star occultations. In 1874, Abetti went to Muddapur, Bengal, to observe the transit of Venus across the sun's disk where his use of a spectroscope was the first use of this kind. Later, he became director at the Arcetri Observatory and Professor of astronomy at the University of Florence (1894-1921). The observatory had been founded by G. B. Donati in 1872, and Abetti equipped it with a new telescope that he had built in the workshops at Padua. He was active after retirement, until his death, and was followed by his son Giorgio.*TIS

**1851 Silvanus P. Thomson**(19 June 1851 – 12 June 1916) In 1910 he published Calculus Made Easy, which was published anonymously until after his death in 1916. It is still in print. *VFR He was a noted physicist and engineer, and a celebrated teacher and writer on electricity and magnetism. He also wrote popular biographies of Faraday and Lord Kelvin. At his death he was professor at City and Guilds Technical College at Finsbury (London). Thompson’s particular gift was in his ability to communicate difficult scientific concepts in a clear and interesting manner. He attended and lectured at the Royal Institution giving the Christmas lectures in 1896 on Light, Visible and Invisible with an account of Röntgen Light. He was an impressive lecturer and the radiologist AE Barclay said that: “None who heard him could forget the vividness of the word-pictures he placed before them.”

**DEATHS**

**1504 Bernhard Walther**(1430 – June 19, 1504) was a German merchant, humanist and astronomer based in Nuremberg, Germany.

Walther was born in Memmingen, and was a man of large means, which he devoted to scientific pursuits. When Regiomontanus settled in Nuremberg in 1471, they worked in collaboration to build an observatory and a printing press. After the death of Regiomontanus in 1476 at Rome, Walther bought his instruments, after Hans von Dorn, commissioned by the Hungarian king, had tried in vain about it with the council of Nuremberg. Thenceforward, he continued the observation of planets till his death in Nuremberg. His house, purchased in 1509 by Albrecht Dürer, is nowadays a museum

**1945 Stefan Mazurkiewicz**(September 25, 1888 in Warsaw, then Russian Empire – June 19, 1945, Grodzisk Mazowiecki, Poland)one of the founders of Fundamenta Mathematicae, died.

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