Wednesday, 5 August 2026

On This Day in Math - August 6

  



God exists since mathematics is consistent,
and the Devil exists since we cannot prove it
.

~André Weil


The 218th Day of the Year
109 is the sum of two squares, 10^2 + 3^2. Can you see how to use this to get the sum of squares of 2x 109?
218 = 7^2 + 13^2  Students might try this with other sums of squares and see what else they can find.   
  




218 = 6^3 + 1^3 + 1^3, and the difference of two cubes, 7^3 - 5^3.

218 is the number of nonequivalent ways to color the 12 edges of a cube using at most 2 colors, where two colorings are equivalent if they differ only by a rotation of the cube.

The sum of its digits is 11, the sum of its prime factors is 111.

218 is a palindrome in base 9, 262_9

218 is the smallest number with a Merten funtion =3. (an acceptable definition for students is that the Merten number for n, M(n), is the count of square-free integers up to n that have an even number of prime factors, minus the count of those that have an odd number.) The function is named in honor of Franz Merten, who was a teacher of Schrodinger.

218 is the number of points on a 6x6x6 space lattice


See More Math Facts for every Year Date here




EVENTS


1181 a supernova was observed by Chinese astronomers in the constellation now known as Cassiopeia, and independently found one day later from Japan. The "guest star" remained visible for 185 days (over 6 months). A supernova remnant, 3C58, found by radio astronomers in the 1960's, was first proposed to be the remnant of the supernova 1181 by F. Richard Stephenson. 3C58 is a filled-center supernova remnant, extends now about 9x5 arc minutes and contains a pulsar which rotates about 15 times per second. In addition, an extended X-ray source surrounding the pulsar has been observed, thought to be produced by a cloud of high-energy particles about 20 light years across. *TIS

The pullout box shows the inner toroidal-shaped nebula *Wik



1456 According to one story that first appeared in a 1475 posthumous biography and was subsequently embellished and popularized by Pierre-Simon Laplace, Callixtus III excommunicated the 1456 apparition of Halley's Comet, believing it to be an ill omen for the Christian defenders of Belgrade from the besieging armies of the Ottoman Empire. No known primary source supports the authenticity of this account. The 29 June 1456 papal bull of Callixtus III calling for a public prayer for the success of the crusade, makes no mention of the comet. By 6 August, when the Turkish siege was broken the comet had not been visible in either Europe or Turkey for several weeks. 

The siege of Belgrade, or siege of Nándorfehérvár (Hungarian: Nándorfehérvár ostroma or nándorfehérvári diadal, lit. "Triumph of Nándorfehérvár"; Serbian Cyrillic: Опсада Београда, romanized: Opsada Beograda) was a military blockade of Belgrade that occurred 4–22 July 1456 in the aftermath of the fall of Constantinople in 1453 marking the Ottomans' attempts to expand further into Europe. Led by Sultan Mehmed II, the Ottoman forces sought to capture the strategic city of Belgrade (Hungarian: Nándorfehérvár), which was then under Hungarian control and was crucial for maintaining control over the Danube River and the Balkans.

The Hungarian defenders, under the leadership of John Hunyadi, who had garrisoned and strengthened the fortress city at his own expense, put up a determined resistance against the larger Ottoman army. The siege lasted for several weeks, during which both sides suffered heavy losses. The defenders used innovative tactics, including the use of heavy artillery and firearms, to repel the Ottoman assaults. Hunyadi's relief force destroyed a Turkish flotilla on 14 July 1456 before defeating their land forces outside Belgrade on 21–22 July. Wounded Mehmed II was compelled to lift the siege and retreat on 22 July 1456. This victory boosted the morale of European Christian forces and was seen as a turning point in their efforts as it provided a crucial buffer and temporarily halted Ottoman expansion in Europe. *Wik  

Ottoman miniature of the siege of Belgrade, 1456



1531  Petrus Apianus begins his observations and sketches of the 1531 comet that would become known in later years as Halley's comet.  He was the first to say that the comet's tail always pointed away from the sun.  His writings and measurements were part of the evidence that led to Halley rejecting Newton's conjecture that comets followed parabolic paths, and plotted out estimates for the comets return using elliptic orbits.


This image appeared in his Astronomicum Caesareum, unusual also for his use of several Volvelles that allowed users to calculate dates, the positions of constellations.  volvelle or wheel chart is a type of slide chart, a paper construction with rotating parts. It is considered an early example of a paper analog computer.
*Wik



1618 Johannes Kepler determined the distance to the sun to be 225 mil km. *NSEC  This was after he had the inspiration in March of the same year for what came to be known as the third law of planetary motion.  

[For the Students: Kepler's Third Law: the squares of the orbital periods of the planets are directly proportional to the cubes of the semi-major axes of their orbits. Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit.



In 1753, Professor Georg Richmann of St. Petersburg, Moscow, was killed by his experiment with lightning. One year after Benjamin Franklin's kite experiment, Richmann attached a wire to the top of his house and led it down to an iron bar suspended above "the electric needle" and a bowl of water partly filled with iron filings*. It was reported that during a storm, Richmann was struck while about a foot from the bar, and closely observing the needle. "A globe of blue and whitish fire about four inches diameter" from the bar struck Richmann's forehead" with "an explosion like that of a small cannon." His assistant, M. Sokolaw, who survived, was thrown to the floor feeling blows on his back. He found marks of burning hot wire fragments on the back of his clothes.*TIS

After his education, Richmann spent the rest of his life as a professor of physics at the university in St. Petersburg and a center of scientific research. There he dealt with problems of thermodynamics and with investigations of electrical phenomena.

He became famous above all for establishing the first general equation for calorimetric calculations. This law was later called Richmann's law in his honor.

Richmann also became famous for his investigations on thunderstorm electricity, which led to his tragic death in 1753. Richmann also worked as a tutor to the children of Count Andrei Osterman.[citation needed] Richmann translated Alexander Pope's Essay on Man into German from French, which appeared in 1741.[citation needed] In that year, he was also elected a member of the St. Petersburg Academy of Sciences.*Wik



1763   Alexander Wilson was awarded an honorary degree by the University of St Andrews. He was a Scottish surgeon, type-founder, astronomer, mathematician and meteorologist. 

Wilson made the first recorded use of kites in meteorology with his lodger, a 23-year-old University of Glasgow student Thomas Melvill. They measured air temperature at various levels above the ground simultaneously with a train of kites. Melvill went on to discover sodium light. Wilson was also the inventor of hydrostatic bubbles, a form of hydrometer, 

 He was known for his sunspot studies and Wilson noted that sunspots viewed near the edge of the Sun's visible disk appear depressed below the solar surface, a phenomenon referred to as the Wilson effect. When the Royal Danish Academy of Sciences and Letters announced a prize to be awarded for the best essay on the nature of solar spots, Wilson submitted an entry. On 18 February 1772 the Academy presented Wilson with a gold medal for his work on sunspots. *Wik




1855 Thomas Penyngton Kirkman presented a paper on the general question of determining a condition under which a graph is Hamiltonian. Unlike Hamilton, who was primarily interested in the algebraic connections of one specific graph, Kirkman was  interested in the general study of ‘Hamiltonian circuits’ in arbitrary graphs. He was the rector of a small and isolated English parish, but made regular and important contributions to mathematics. His solution of the problem was incorrect; but he did present a second paper in 1856 in which he described a general class of graphs which do not contain such a circuit. Kirkman also studied the existence of Hamiltonian circuits on the dodecahedron, a variation of the Icosian Game which Hamilton also studied. In fact, the two men met once in 1861 when Hamilton visited Kirkman at his rectory. That Hamilton’s name became associated with the circuits, and not Kirkman’s, appears to be one of the accidents of history, or perhaps a credit to the fame of Hamilton’s quarternions and work in mathematical physics. *Janet Barnett, Early Writings on Graph Theory


1926 Gertrude Ederle, age 19, of New York became the first woman to swim the English Channel, breaking the men’s record by nearly two hours.

She started at Cap Gris-Nez in France at 07:08 am on August 6, 1926, and came ashore at Kingsdown, Kent, 14 hours and 34 minutes later, having swum the equivalent of 35 miles due to stormy conditions taking her past her anticipated end point. The first person to greet her was a British immigration officer who requested a passport from "the bleary-eyed, waterlogged teenager". Her record stood until Florence Chadwick swam the Channel in 1950 in 13 hours and 23 minutes.:

Prior to Ederle, only five men had completed the swim across the English Channel, with the best time of 16 hours, 33 minutes by Enrique Tirabocchi. *PB notes




1945 First atomic bomb explosion over a populated area, Hiroshima, Japan, from the Enola Gay, a B-29 bomber. The pilot was Colonel Paul Tibbits, the bombardier, Major Thomas Ferebee. *VFR The city was chosen because it had not been bombed and its area was perfect for evaluating the effect of the bomb.

The Hiroshima Peace Memorial (広島平和記念碑, Hiroshima Heiwa Kinenhi), originally the Hiroshima Prefectural Industrial Promotion Hall, and now commonly called the Genbaku Dome, Atomic Bomb Dome or A-Bomb Dome (原爆ドーム, Genbaku Dōmu), is part of Hiroshima Peace Memorial Park in Hiroshima, Japan, and was designated a UNESCO World Heritage Site in 1996.

The building is a prominent structure that remained standing in the area around the atomic bombing of Hiroshima on 6 August 1945, three days before the atomic bombing of Nagasaki and nine days before Japan surrendered, ending World War II. The ruin serves as a memorial to the over 140,000[2] people killed in the bombing. It is permanently kept in a state of preserved ruin as a reminder of the destructive effects of nuclear warfare. *Wik 








1997 In an effort to help save Apple Computer and possibly deflect criticism in its own anti-trust trial, Microsoft Corp. buys $150 million in shares of Apple Computer Inc. Apple, which had been struggling to find direction and profits for years, agreed to the boost in funding with terms that dictated cooperation in the design of computers as well as shared patents. Microsoft agreed to continue supporting MS-Office for the Mac for another five years as well. *CHM



2002 The first Polynomial-time primality test was published. The first provably polynomial time test for primality was invented by Manindra Agrawal, Neeraj Kayal and Nitin Saxena. The AKS primality test, runs in Õ((log n)12) (improved to Õ((log n)7.5) in the published revision of their paper), which can be further reduced to Õ((log n)6) if the Sophie Germain conjecture is true. Subsequently, Lenstra and Pomerance presented a version of the test which runs in time Õ((log n)6) unconditionally. *Wik


2003 After 61.40 days of computation, a 150-year-old unsolved problem has finally been answered, there is no 8x8 knights tour which forms a magic square. A knight's tour is a sequence of moves of a knight on a chessboard such that the knight visits every square only once. The earliest known reference to the knight's tour problem dates back to the 9th century AD. In Rudraṭa's Kavyalankara, a Sanskrit work on Poetics. If starting square is labled "one" and each square it lands on is numbered sequentially, an 8x8 number square is formed. If that square is a magic square, then you have formed a magic knights tour (except now we know you can't). It has long been known that magic knight's tours are not possible on n x n boards for n odd. It was also known that such tours are possible for all boards of size 4k x 4k for k > 2.
This longstanding open problem has now been settled in the negative by an exhaustive computer enumeration of all possibilities. The software for the computation was written by J. C. Meyrignac, and the website was established by Guenter Stertenbrink to distribute and collect results for all possible tours. After 61.40 CPU-days, corresponding to 138.25 days of computation at 1 GHz, the project was completed on August 5, 2003. What are the results? In addition to netting a total of 140 distinct semimagic knight's tours, the computation demonstrated for the first time that no 8 x 8 magic knight's tour is possible, thus finally laying this long-open problem to rest. *Mathworld

a semi-magic square where rows and columns sum to 260, but the diagonals do not.

Historical Example: William Beverley published a famous semi-magic knight's tour in 1848 where every row and column adds up to 260, and each half-row and half-column sums to 130.




2011 During the first excavation campaign of the Paphos Agora Project (3rd July – 6th August 2011), an interesting object was discovered. An ancient, two-sided amulet with a 59-letter palindromic inscription. It was translated in the following way: “Yahweh is the bearer of the secret name, the lion of Re secure in his shrine”.
The opposite side of the amulet has several images, including a bandaged mummy (likely representing the Egyptian god Osiris) lying on a boat and an image of Harpocrates, the god of silence, who is shown sitting on a stool while holding his right hand up to his lips. Strangely, the amulet also displays a mythical dog-headed creature called a cynocephalus, which is shown holding a paw up to its lips, as if mimicking Harpocrates' gesture. *livescience


2015 Three planets and our moon put on a show for astronaut Scott Kelly, who spent a year aboard the International Space Station to conduct research of long-duration space flight.

Kelly's Tweet from space: ""Day 114. #Moon #Venus #Jupiter...#Earth Good night from @space_station! #YearInSpace"

From bottom to top: Earth's Moon, Venus, Jupiter and the crescent of Earth at the top.



BIRTHS


1638 Nicolas Malebranche(6 August 1638 – 13 October 1715) was a major French philosopher and follower of Descartes whose ideas he developed to bring them more in line with standard Roman Catholic orthodox belief.*SAU



1667 Johann (Jean) I Bernoulli born. ( August 6, 1667– 1 January 1748) was a Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is known for his contributions to infinitesimal calculus and educated Leonhard Euler in his youth. In 1691 Johann Bernoulli again fueled the tensions between himself and his brother when he solved the problem of the catenary presented by Jakob. In 1696 Johann Bernoulli proposed the problem of the brachistochrone, despite already having solved the problem himself. Within two years he received five answers, one of which was from his older brother, Jacob. Bernoulli also proposed a fluid energy perpetual motion machine.
Bernoulli was hired by Guillaume François Antoine de L'Hôpital to tutor him in mathematics. Bernoulli and L'Hôpital signed a contract which gave L'Hôpital the right to use Bernoulli’s discoveries as he pleased. L'Hôpital authored the first textbook on infinitesimal calculus, "Analyse des Infiniment Petits pour l'Intelligence des Lignes Courbes", which mainly consisted of the work of Bernoulli, including what is now known as L'Hôpital's rule. *Wik



1741 John Wilson (6 August 1741, Applethwaite, Westmorland – 18 October 1793, Kendal, Westmorland) born English laywer and mathematician. The theorem that bears his name [If p is prime, then (p − 1)! ≡−1 (mod p)] was published without proof in Waring’s Meditationes algebraicae of 1770, but we now know that Leibniz knew the result. The first published proof was by Lagrange (1773), who showed that it is equivalent to Fermat’s Little Theorem of 1640: If p is prime and  p divides a Then ap−1 ≡ 1 (mod p).
Euler first proved this in 1736. Lagrange also showed that the converse of Wilson’s Theorem is true. (The converse of Fermat’s is false—the counterexamples are called pseudoprimes.) Sir Frederick Pollack has conjectured that Wilson’s Theorem was a guess that neither he nor Waring could prove. See DeMorgan’s Budget of Paradoxes. *VFR In the 11th century Alhazen (Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham )solved problems involving congruences using what is now called Wilson's theorem. In his Opuscula, Alhazen considers the solution of a system of congruences, and gives two general methods of solution. His first method, the canonical method, involved Wilson's theorem, while his second method involved a version of the Chinese remainder theorem.



1766 William Hyde Wollaston (6 August 1766 – 22 December 1828), British Doctor and chemist. He saw in 1802 the Fraunhofer lines in the Solar spectrum but considered it as a limitation of colors. *NSEC
He is also known for discovering two chemical elements and for developing a way to process platinum ore. Wollaston also performed important work in electricity. In 1801, he performed an experiment showing that the electricity from friction was identical to that produced by voltaic piles. *Wik



1838 George James Symons (6 Aug 1838 - 10 Mar 1900) British meteorologist who strove to provide reliable observational data by imposing standards of accuracy and uniformity on meteorological measurements and by substantially increasing the number of reporting stations from 168 to 3,500. He was elected to Royal Meteorological Society (1856) when only 17 years old. He established the British Rainfall Organization (1860) and issued annual rainfall reports (1860-98). Symons's Monthly Meteorological Magazine first appeared in 1866. He wrote hundreds of articles and several books, and he amassed the UK's most comprehensive collection of meteorological books, many of great historical interest.*TIS




1844  James Henry Greathead(6 August 1844 – 21 October 1896) a British civil engineer.  Greathead, working with Peter Barlow, built the first subway tunnel under the Thames (and the second Thames tunnel ever), completing the Tower Subway in 1870.  To accomplish this, he utilized a tunneling shield of his own design that was different from the first tunneling shield, used by Marc Isambard Brunel in building the first Thames tunnel from 1825 to 1843 .  Greathead's shield was cylindrical, rather than square as Brunel's had been.  Workers entered the shield through a small door, shoveled out dirt behind the shield, and then the shield was jacked forward by screws, and cast iron segments were bolted in place behind it as it inched forward.  The result was a "tube," the first tube.  Barlow had invented and patented a similar shield in 1868, but it was never built, and it appears Greathead was unaware of the patent and designed his independently.  The first Greathead shield was only 7.25 feet across, so the resulting tube was small and the cars that would fit through it even smaller . The train of cars was pulled though the tunnel by a cable connected to a stationary engine on the bank.  *Linda Hall Org




1943 Jonathan Bruce Postel (August 6, 1943 – October 16, 1998) was an American computer scientist who played a pivotal role in creating and administering the Internet. In the late 1960s, Postel was a graduate student developing the ARPANET, a forerunner of the Internet for use by the U.S. Dept. of Defense. As director of the Internet Assigned Numbers Authority (IANA), which he formed, Postel was a creator of the Internet's address system. The Internet grew rapidly in the 1990s, and there was concern about its lack of regulation. Shortly before his death, Postel submitted a proposal to the U.S. government for an international nonprofit organization that would oversee the Internet and its assigned names and numbers. He died at age 55, from complications after heart surgery.*TIS




DEATHS


1694 Antoine Arnauld (Feb 6, 1622; Aug 6, 1694) was a French supporter of Jansen who published some important works on logic and philosphy. 

Antoine Arnauld, sometimes called The Great Arnauld, was the son of Antoine Arnauld senior (1560-1619) and Catherine Marie de Druy. Antoine Arnauld senior and his wife were the founders of a French family of the lesser nobility who became the leading Jansenist family of France.

Jansenists were followers of Cornelist Otto Jansen (1585-1638) who led a Roman Catholic reform movement named after him. Jansen put forward his views in Augustinus (1640) which he based on the teachings of St Augustine, particularly St Augustine's arguments against Pelagius. Pelagius had argued that men can achieve salvation through their actions but Jansen argued that men cannot achieve salvation through their actions since it is predestined who Christ will lead to eternal life, the select few, and who are doomed to damnation, the multitude. *SAU




1879 Johann Von Lamont (December 13, 1805; Corriemulzie, Scotland - August 6, 1879 Munich, Germany) Scottish-born German astronomer noted for discovering (1852) that the magnetic field of the Earth fluctuates with a 10.3-year activity cycle, but does not correlate it with the period of the sunspot cycle. From 1 Aug 1840, Johann von Lamont (as director of the Royal Astronomical Observatory in Munich) started regular and permanent observations of the earth's magnetic field. In the 1850's he started making regional magnetic surveys in the kingdom of Bavaria, later extended to other states in south Germany, France, Holland, Belgium, Spain, Portugal, Prussia and Denmark. His central European maps with isolines of geomagnetic elements, reduced to 1854, were the first worldwide*TIS




1925 Gregorio Ricci-Curbastro (12 January 1853 – 6 August 1925) Much of Ricci-Curbastro's work ... was done jointly with his student Levi-Civita. In a fundamental joint paper that year Méthodes de calcul différentiel absolu et leurs applications he used (for the only time) the name Ricci instead of his full name. This paper had been requested five years earlier by Klein. The authors state their aims in the preface to their important seventy-seven page paper:-
The algorithm of absolute differential calculus, the instrument matériel of the methods ... can be found complete in a remark due to Christoffel. But the methods themselves and the advantages they offer have their raison d'être and their source in the intimate relationships that join them to the notion of an n-dimensional variety, which we owe to the brilliant minds of Gauss and Riemann. ... Being thus associated in an essential way with Vn, it is the natural instrument of all those studies that have as their subject, such a variety, or in which one encounters as a characteristic element a positive quadratic form of the differentials of n variables or of their derivatives.
In the paper, applications are given by Ricci-Curbastro and Levi-Civita to the classification of the quadratic forms of differentials and there are other analytic applications; they give applications to geometry including the theory of surfaces and groups of motions; and mechanical applications including dynamics and solutions to Lagrange's equations. The main ideas of this paper are discussed in. Ricci-Curbastro's absolute differential calculus became the foundation of tensor analysis and was used by Einstein in his theory of general relativity. *SAU




1945 Paul Koebe; (February 15, 1882, Luckenwalde, Brandenburg – August 6, 1945) Koebe's work was all on complex functions, his most important results being on the uniformisation of Riemann surfaces. Shortly after 1900 Koebe established the general principle of uniformisation which had been originally conceived by Klein and Poincaré. Koebe's proof of the uniformisation theorem has been described as: ... arguably one of the great theorems of the century. *SAU




1970 Joichi Suetsuna (Japanese: 末綱 恕一 Suetsuna Joichi; alternative Romanziation: Zyoiti Suetuna; November 28, 1898 – August 6, 1970) was a Japanese mathematician who worked mainly on number theory. In addition to working in Japan, where he held a chair at Tokyo University and was eventually selected to the Japan Academy, Suetsuna also spent time studying in Europe and introduced to Japan research styles he witnessed there. Later in life, especially after World War II, he studied Buddhist philosophy.

He was a teacher of Hirofumi Uzawa.




1998 André Weil (6 May 1906 – 6 August 1998) was a French mathematician who worked on algebraic geometry and number theory.*SAU ..renowned for the breadth and quality of his research output, its influence on future work, and the elegance of his exposition. He is especially known for his foundational work in number theory and algebraic geometry. He was a founding member and the de facto early leader of the influential Bourbaki group. The philosopher Simone Weil was his sister.*Wik
To avoid the draft, he went to Finland. ''As a soldier,'' he said, ''I would be entirely useless, but as a mathematician I could be of some use.'' The Finns returned him to the French, who imprisoned him for six months. In prison, he created the Riemann hypothesis -- named for a German mathematician -- which became a basic element of number theory and is regarded as one of his most insightful mathematical achievements, Dr. Phillips said.



2002 Edsger Wybe Dijkstra (May 11, 1930 – August 6, 2002)was a Dutch computer scientist. He received the 1972 Turing Award for fundamental contributions to developing programming languages, and was the Schlumberger Centennial Chair of Computer Sciences at The University of Texas at Austin from 1984 until 2000. Among his contributions to computer science are the shortest path-algorithm, also known as Dijkstra's algorithm; Reverse Polish Notation and related Shunting yard algorithm; the THE multiprogramming system, an important early example of structuring a system as a set of layers; Banker's algorithm; and the semaphore construct for coordinating multiple processors and programs. Another concept due to Dijkstra in the field of distributed computing is that of self-stabilization – an alternative way to ensure the reliability of the system. Dijkstra's algorithm is used in SPF, Shortest Path First, which is used in the routing protocols OSPF and IS-IS. *Wik




2007 Atle Selberg (14 June 1917 – 6 August 2007) was a Norwegian mathematician known for his work in analytic number theory, and in the theory of automorphic forms, in particular bringing them into relation with spectral theory. He was awarded the Fields Medal in 1950.*Wik



2012 Sir Alfred Charles Bernard Lovell (31 August 1913 – 6 August 2012) is an English radio astronomer who established and directed (1951-81) Jodrell Bank Experimental Station, Cheshire, England, with (then) the world's largest steerable radiotelescope, now named after him Prior to WW II, he worked at Manchester University on cosmic ray research. During the war, he helped develop aircraft onboard radar systems. After the war, to escape interference to radar equipment from city trams, he moved his research to the University's more remote Jodrell Bank property. In 1946, he showed that radar echoes could detect optically invisible daytime meteor showers. He gained funding to build the 250-ft-diam. telescope. When completed in 1957, it was able to track the first artificial satellite, Sputnik I. *TIS

The Lovell Telescope at Jodrell Bank, *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




Easy?!?! Computations for the Back of a Napkin

Another from the Archives, Enjoy!


Some calculations are easier than you think! I’m drawn to math that can be done on a napkin at a restaurant. Quick mental calculations and methods of approximation that give you the ball park quick answer…”It’s about …blah.” and then I try to look as if I don’t think I’m really clever. I had a couple of these come up recently, so I thought I would share…

One was at a backyard barbecue…an electrical engineer, a graduate physics student, and a math teacher, beers in hand as the hamburgers burned and the hot dogs turned to charcoal… One had just come back from New York City and pointed out that the Empire State bldg. was 1224 feet high to the upper observatory… then someone brought up the old conjecture that a penny dropped from the Empire State building would kill you. The engineer suggests that in truth the penny would reach some terminal velocity that would keep it from actually killing anyone. The physics student suggests that it would not be too hard to figure out using differential equations if we just ignored the air resistance, but he didn’t have his calculator (which apparently is his main resource for doing integration). The math teacher offers, “Well, with only high school math and physics, and a little mental calculation, it should be about 280 feet per second.”

A long silence, followed by “How did you get that number?” So I explained. In physics the big ideas often provide great simplifications…and in this case the big idea was the conservation of energy laws…. The total energy remains constant. The Penny on the 102nd floor has a potential energy equal to its weight times its height. When it hits the ground the potential energy has all been converted to kinetic energy (and a very small amount of heat due to air friction which I ignore) . Epot= m g h and Ekin = ½ m v^2. Cancel the mass on each side and we have gh = ½ v^2. If we use the common value of 32 ft/sec2 for the gravitational force, then we can simplify this all down to v^2= 64 h.. or taking square roots, we get v= 8 times the square root of h…. Now the square root of 1224 is about the same as the square root of 1225 which is 35 (one of those multiplication tricks I teach my students each year) and 8 x 35 = 280, so the answer is about 280 ft/second.

They both look incredulous… so I offer a second approach… OK, an object dropped from rest will fall 16t2 feet in t seconds. To fall 1224 seconds it would take t=sqrt(1224/16) and taking the square root of top and bottom we get 35/4 seconds… OK, so velocity is 32 times t, so 32 times 35/4 = (wait for it…. ) 8 x 35 = 280 again… “Easier than you thought… right”

The second event corrected a misconception I have had for years. I have mentioned earlier that one of my preoccupations on the road is looking at mile markers and license plate numbers and trying to factor them. I know all the easy tricks for divisibility by small numbers, except seven…. The rules for divisibility by seven always seemed harder than just dividing by seven, so I was surprised to read a note from a guy who seems to have invented (I never saw it before) an easy way to test divisibility by seven

Without going into the derivation, here is the rule. Take the number, call it N, and think of it as 10A + B. For example if the number is 2345 the A = 234 and the B= 5. Now the method is just to calculate A-2B and if that answer is divisible by seven, so is the original. And if you don’t know, just reapply the same rule again. For example 2345 is divisible by 7 only if 234-10 = 224 is also….which can be applied again with 22-8 = 14… ohh….. I KNOW that is a multiple of seven, so 2345 is also a multiple of seven, in fact it is 7 x 335.

This is getting a little long, so on a later day I’ll explain how he found it, and even show you a method I found for testing 13 which is almost as easy, and another for testing divisibility by 17… as the tv folks say….stay tuned 

Ok, I put this off for a long time, but here is the reason for the A-2B approach:

Suppose we have a number that is (or isn't) divisible by 7.  you could test divisibility by simply removing multiples of seven until you gey down to a number you know by heart.  In some ways this is the most understandable way of all.  Is 34265 divisible by seven?  Well 2800 is, so we can subtract that to get 6265.  if 34265 is divisible by 7 then so is 6265.  We can work on the other end also.  6265-(9x7)= 6202 and our line of plausibility still stands....either all these numbers are divisible by seven, are all of them are not.  What about lopping off 5600 from 6202. now we are down to 602.  Now 560 looks like a good reduction, and we are down to 42... I think I know that one.  

Ok, so A-2B.... remember the test number is N=10 A + B  and 10≡3(mod7),   sooo N≡3A+B(mod7).

So checking divisibility by 7 is equivalent to asking whether 3A+B0(mod7).

It seems trivial (but it is helpful) to write 2(3A+B)=6A+2B.   Since 6≡−1(mod7),

this becomes   2(3A+B)≡−A+2B≡−(A−2B)(mod7). And that's all there is too it.


On This Day in Math - August 5

  


Mathematics is like checkers in being suitable for the young,
not too difficult, amusing, and without peril to the state. 

~Plato

On non-leap years, this is the 217th day of the year; 217 is both the sum of two positive cubes and the difference of two positive consecutive cubes in exactly one way: 217 = 63 + 13 = 93 − 83. (How frequently would the difference of two consecutive cubes also be expressible as the sum of two cubes?)

on leap years this is the 218th day of the year; 218 = 72 + 132

218 is the number of nonequivalent ways to color the 12 edges of a cube using at most 2 colors, where two colorings are equivalent if they differ only by a rotation of the cube. 

218 is the smallest number with a Merten funtion =3. (an acceptable definition for students is that the Merten number for n, M(n), is the count of square-free integers up to n that have an even number of prime factors, minus the count of those that have an odd number.) The function is named in honor of Franz Merten, who was a teacher of Schrodinger.
More Math Facts for every Year Day here


EVENTS

1638 One of the early reports on hurricanes came from John Taylor, domestic adventurer, poet, propagandist, Royalist, and sometime overseer of the Company of Watermen in London. In 1638 he seems to have published New and Strange News from St. Christophers, of a tempestuous Spirit, which is called by the Indians a Hurry Cano, which happeneth in many of those Islands of America, or the West-Indies, as it did in August last the 5. 1638. Blowing downe houses, tearing up trees by the rootes, and it did puffe men up from the earth, as they had beene Feathers, killing divers men. *PACHS blog

For those, like me, who are not sure of the meaning of Watermen, "A waterman is a river worker who transfers passengers across and along city centre rivers and estuaries in the United Kingdom and its colonies. Most notable are those on the River Thames and River Medway in England, but other rivers such as the River Tyne and River Dee, Wales, also had their watermen who formed guilds in medieval times. Waterman can also be a person who navigates a boat carrying passengers. These boats were often rowing boat or boats with sails. Over the years watermen acquired additional skills such as local pilotage, mooring vessels at berths, jetties, buoys, and docks, and acting as helmsman aboard large vessel." *Wik

The Doggett's Coat and Badge, the oldest rowing race in the world, sees apprentice watermen competing on the River Thames.  painting by Thomas Rowlandson (1756–1827).




1775 Montucla, who was the anonymous editor, served as Royal Censer for a new edition of Jacques Ozanam’s book on mathematical recreations (the first edition was written in Ozanam’s spare time during war time and published in 1694). *VFR The book was later published in English by Charles Hutton in 1803.

Hutton rose from digging coal in the Newcastle area to start his own mathematical school and became an English mathematician and surveyor. He was professor of mathematics at the Royal Military Academy, Woolwich from 1773 to 1807. He is remembered for his calculation of the density of the earth from Nevil Maskelyne's measurements collected during the Schiehallion experiment.


*MAA



1766 Eclipse observed southeast of Newfoundland: Eclipse Island (part of Burgeo Islands). Mentioned in the Chronology of Captains James Cooks (1728-1779) travels by Paul Capper. *NSEC


In 1816, Francis Ronalds built a working telegraph in the garden of the family house in Hammersmith in west London. Part of it was underground, but above ground he strung out 8 miles of insulated wire in ribbon-candy fashion, with clocks at each end whose faces contained letters instead of numbers; the electrical signals in some way synchronized the clocks and spelled out a message.  Apparently, the device worked; he gave a demonstration on 5 August, 1816 for the Admiralty, offering it to them gratis, but the Secretary of the Admiralty, John Barrow, rejected it as an unnecessary invention, preferring the semaphore telegraph then in use.  Two years later, Barrow distinguished himself by sending out the first ships in search of a Northwest Passage, but he has never quite lived down the ignominy of rejecting the electrical telegraph as useless.  It would be 20 more years before England re-entered the telegraph business, and by that time, they were well behind the Americans.  Many today regard Ronalds as the true inventor of the telegraph, and there was considerable scholarly commotion in his behalf in 2016, the bicentennial of his invention. *Linda Hall Org

*Linda Hall Org


*Wik



In 1864, Giovanni Batista Donati (1827-73) made the first spectroscopic observations of a comet tail (from the small comet, Tempel, 1864 II). At a distance from the Sun the spectrum of a comet is identical to that of the Sun, and its visibility is due only to reflected sunlight. Donati showed that comet tail formed close to the Sun contains luminous gas. In the spectrum of light from the comet tail, Donati saw three absorption lines bands superimposed on a continuous spectrum, which he named alpha, beta and gamma, and are now known as the Swan bands. These bands were also seen in a comet tail viewed by Pietro Secchi in 1866. Sir William Huggins (1868) identified that these were due to the presence of carbon (molecular carbon, C2).*TIS

Swan bands are a characteristic of the spectra of carbon stars, comets and of burning hydrocarbon fuels.They are named for the Scottish physicist William Swan, who first studied the spectral analysis of radical diatomic carbon (C2) in 1856. *Wik 



1900  On this day in 1900, the engineer Frank Baldwin was awarded a U.S. Patent for his mechanical calculator. This machine was capable of doing a calculation such as  54679285×3298=180332281930 in about 20 seconds with eight turns of the handle.  The  "Baldwin Computing Engine", a machine by which multiplication or division was performed by one stroke for each digit.

1902 model 



1912  “At the final session of the Spectral Classification Committee, on August 5, the Solar Union dissolved its old committees and regrouped into new ones for the work to be done over the next three years, before they would all meet again in Rome. “When the names of committees were read,” wrote Miss Cannon(Annie Jump Cannon, 49 at this time.), “I was very much surprised to find that I was put on the Committee on Classification of Stellar Spectra—and one of the novel experiences of the summer was to meet with this Committee. They sat at a long table, these men of many nations, and I was the only woman. Since I have done almost all the world’s work in this one branch, it was necessary for me to do most of the talking.””

— The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars by Dava Sobel

With Edward C. Pickering, she is credited with the creation of the Harvard Classification Scheme, which was the first serious attempt to organize and classify stars based on their temperatures and spectral types. She developed the mnemonic "Oh! Be A Fine Girl — Kiss Me!" used by students to memorize the spectral classification of stars. *Wik 




1935 Institute of Mathematical Statistics founded.*VFR The Institute of Mathematical Statistics is an international professional and scholarly society devoted to the development, dissemination, and application of statistics and probability. The Institute currently has about 4,000 members in all parts of the world. Beginning in 2005, the institute started offering joint membership with the Bernoulli Society for Mathematical Statistics and Probability as well as with the International Statistical Institute.




1962 a lunar occultation on August 5 enabled Australian radio astronomers to more precisely fix the location of the previously known radio source 3C 273, in Virgo. In 1963 this became the first member of a new class of object eventually to be called quasars or "quasi-stellar radio sources." Maarten Schmidt, using the Hale optical telescope, saw it as a faint star-like object with a visible jet. Its spectrum featured unusual emission lines, which he identified as ordinary hydrogen lines shifted toward longer wavelengths (redshifted) by 16%. If the shift is due to velocity, it is moving away at one-sixth the speed of light and one of the most distant objects visible. Quasars radiate as much energy per second as a hundred or more galaxies. 3C273 is the brightest quasar known.*TIS

image:3C 273 as imaged by the Hubble Space Telescope's Advanced Camera for Surveys. Light from the bright quasar nucleus is blocked by a coronagraph so that the surrounding host galaxy can be more easily seen. Credit: NASA/ESA,  *Wik



1977 Fermilab announces the discovery of what would come to be known as the Bottom Quark. In the summer of 1977, a team of physicists, led by Leon M. Lederman, working on experiment 288 in the proton center beam line of the Fermilab fixed target areas discovered the Upsilon. This discovery was eventually understood as being the bound state of the bottom quark and its antiquark. Their data was confirmed in experiments conducted in 1978 *Fermilab History and Archives Projec 

The bottom quark or b quark, also known as the beauty quark, is a third-generation heavy quark with a charge of −1/3 e.   All quarks are described in a similar way by electroweak and quantum chromodynamics, but the bottom quark has exceptionally low rates of transition to lower-mass quarks. The bottom quark is also notable because it is a product in almost all top quark decays, and is a frequent decay product of the Higgs boson.

The bottom quark was first described theoretically in 1973 by physicists Makoto Kobayashi and Toshihide Maskawa to explain CP violation. The name "bottom" was introduced in 1975 by Haim Harari.

Kobayashi and Maskawa won the 2008 Nobel Prize in Physics for their explanation of CP-violation.  *Wik

Image  Wilson Building at Fermilab, named for former director Robert R. Wilson, was reportedly inspired by the Gothic cathedral in Beauvais, France. 



1982 Cook 3061 (1982 UB1): Minor planet discovered October 21, 1982 by E. Bowe II at Anderson Mesa. Named for James Cook (1728-1779), British circumnavigator and one of the first scientific navigators. He observed the Solar Eclipse of 1766 August 5 from Newfoundland and in 1769 measured the transit of Venus from Tahiti. Named proposed by the discoverer.*NSEC






BIRTHS


1798 John Wrottesley, 2nd Baron Wrottesley, (5 August 1798 – 27 October 1867) was an English astronomer, who published Catalogue Of The RA Of 1318 Stars. He was a founder member of the Royal Astronomical Society. From his first Observatory in Blackheath, London, he recorded over 12,000 observations. After he inherited the title and the Staffordshire family estate at Wrottesley in 1841, he built an observatory there. In 1855, the city of Wolverhampton nearby decreed that if any ... furnace chimney ...was built ... within three miles of the observatory, it shall be constructed on the best and approved principles "for consuming the smoke arising ... therefrom". This of course was so that observations from the observatory would not be hampered by smoke pollution.*TIS



1802 Neils Henrik Abel (5 August 1802 – 6 April 1829) was born at Fomm¨oy, a small island near Stavanger in Norway. Before going to the university in 1821 he attacked, with the vigor and immodesty of youth, the problem of the solution of the quintic equation. He submitted a solution for publication but found an error before it was published. In 1823 he proved the impossibility of a solution involving radicals that solves fifth or higher degree equations. *VFR He developed the concept of elliptic functions independently of Carl Gustav Jacobi, and the theory of Abelian integrals and functions became a central theme of later 19th-century analysis. He had difficulty finding an academic position, was troubled by poverty, and died in poverty in his late twenties.*TIS  I love Abel's comment on Gauss' writing style, "He is like the fox, who effaces his tracks in the sand with his tail."




1855 William Henry Dines (5 August 1855 – 24 December 1927) was an English meterologist and inventor of related measurement instruments such as the Dines pressure tube anemometer (the first instrument to measure both the velocity and direction of wind, 1901), a very lightweight meteorograph, and a radiometer (1920). He joined the Royal Meteorological Society study of the cause of the disastrous Tay Bridge collapse of 1879. His measurements of upper air conditions, first with kites and later by balloon ascents (1907), brought an understanding of cyclones from dynamic processes in the lower stratosphere rather than thermal effects nearer to the ground.*TIS




1855  Alfredo Capelli (5 Aug 1855, Milan, Italy – 28 Jan 1910, Naples, Italy) was an Italian mathematician who discovered Capelli's identity.


Capelli graduated from the University of Rome in 1877, and moved to the University of Pavia where he worked as an assistant for Felice Casorati. In 1881 he became a professor at the University of Palermo, replacing Cesare Arzelà who had recently moved to Bologna. In 1886, he moved again to the University of Naples, where he held the chair in algebra. He remained at Naples until his death in 1910. As well as being a professor there, he was editor of the Giornale di Matematiche di Battaglini from 1894 to 1910, and was elected to the Accademia dei Lincei.*Wik

In mathematics, Capelli's identity, named after Alfredo Capelli (1887), is an analogue of the formula det(AB) = det(A) det(B), for certain matrices with noncommuting entries, related to the representation theory of the Lie algebra . It can be used to relate an invariant ƒ to the invariant Ωƒ, where Ω is Cayley's Ω process.




1878 Louis Charles Karpinski (5 August 1878 – 25 January 1956) was an American mathematician.

He was born on August 5, 1878, in Rochester, New York. His parents were Henry Hermanagle Karpinski of Warsaw, Poland and Mary Louise Engesser of Guebwiller, France. He earned his Bachelor of Arts at Cornell University in 1901 and his Ph.D. at Universität Straßburg in 1903.

At Columbia University, Karpinski became a fellow and a university extension lecturer. He taught at Berea College and at the Normal School in Oswego, New York, now SUNY Oswego. He then accepted a position at the University of Michigan, where he became a full professor of mathematics by 1919. He devoted his attention chiefly to the history and pedagogy of mathematics.

Karpinski served as the president of the History of Science Society from 1943 to 1944



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

Armstrong died following complications resulting from cardiovascular procedures. *Mercury News





1936 Ki-Hang Kim (5 August 1936 – 15 January 2009), also known as Kim Ki-Hang Butler, Hang Kim, Keyhany Keem, or Kim Ki-Hang was a Korean-American Mathematician and Alabama State University professor known for his contributions in semigroups, Boolean matrices, and Social Sciences. He frequently co-wrote with Fred Roush.
Kim graduated from the University of Southern Mississippi in 1960 with a B.S. in mathematics. He received a M.S. a year later, in 1961. Unable to fund a Ph.D., Kim taught briefly at University of Hartford. He then obtained a Ph.D. in mathematics from George Washington University in 1970, for On (0,1)-Matrix Semigroups.

Kim began teaching at St. Mary's College in 1968, moving to Pembroke State University in 1971. Finally, he accepted the position of professor of mathematics and Director of the Mathematics Research Group at Alabama State University. Kim additionally taught at institutions abroad, in Portugal and India, as well as attending many international conferences, including those in China and Hungary, particularly the conference on Algebraic Semigroup Theory in Szeged, Hungary, where he was the only American invited. He was also active in many conferences within the US, including the American Mathematical Society meeting at Auburn University in 1971, Southeastern Conference on Combinatorics, Graph Theory, Computing in Boca Raton, Florida in 1974. Kim spent 35 years teaching at Alabama State University, ending his tenure in 2007.

From 1971 to 1976, Kim published 25 papers on semigroups and Boolean matrices (under the name Kim Butler). Following meeting fellow mathematician Fred Roush, Kim published over 150 more papers over a variety of subjects. He is remembered for bridging the gap between social sciences, particularly economics, psychology, and political sciences. In 1980, he launched and became editor of Mathematical Social Sciences, focusing on Game Theory and Social Choice Theory. Kim also disproved an established theorem dictating the way computer coding was written. Kim wrote seven books, most co-authored by Roush.




1946 Shirley Ann Jackson (August 5, 1946; Washington D.C. - ) is an American physicist, and the 18th president of Rensselaer Polytechnic Institute. She received her Ph.D. in physics from the Massachusetts Institute of Technology in 1973, becoming the first African American woman to earn a doctorate from MIT in nuclear physics.

Jackson joined the Theoretical Physics Research Department at AT&T Bell Laboratories in 1976, examining the fundamental properties of various materials. She began her time at Bell Labs by studying materials to be used in the semiconductor industry. In 1978, Jackson became part of the Scattering and Low Energy Physics Research Department, and in 1988 she moved to the Solid State and Quantum Physics Research Department. At Bell Labs, Jackson researched the optical and electronic properties of two-dimensional and quasi-two dimensional systems. In her research, Jackson has made contributions to the knowledge of charged density waves in layered compounds, polaronic aspects of electrons in the surface of liquid helium films, and optical and electronic properties of semiconductor strained-layer superlattices. On these topics and others she has prepared or collaborated on over 100 scientific articles.
Jackson served on the faculty at Rutgers University in Piscataway and New Brunswick, New Jersey from 1991 to 1995, in addition to continuing to consult with Bell Labs on semiconductor theory. Her research during this time focused on the electronic and optical properties of two-dimensional systems.
In 1995, President Bill Clinton appointed Jackson to serve as Chairman of the U.S. Nuclear Regulatory Commission (NRC), becoming the first woman and first African American to hold that position.*Wik





DEATHS


1729 Thomas Newcomen (shortly before 24 February 1664 – 5 August 1729) inventor of the atmospheric steam engine, died in London. His invention of c.1711 came into use to pump water out of coal mines by 1725. It had a piston connected to one end of a large crossbeam; the other end was connected to a very heavy pump piston. On each stroke, water chilled and condensed the steam in the cylinder, dropping the piston thus moving the crossbeam and operating the pump. This was wasteful of fuel needed to reheat the cylinder for the next stroke. Although it was slow and inefficient, Newcomen's engine was relied on for the first 60 years of the new steam age it began. *TIS





1853 Théodore Olivier (21 Jan 1793 in France - 5 Aug 1853 in France) From the 1840's Olivier wrote textbooks. His greatest fame, however, is as a result of the mathematical models which he created to assist in his teaching of geometry. Some of the models were of ruled surfaces, with moving parts to illustrate to students how the ruled surfaces were generated. Others were designed to illustrate the curves of intersection of certain surfaces. In fact Olivier earned quite a good income from selling these models, particularly in the United States.
The United States Military Academy at West Point had 23 mathematical models made for them by Olivier to use as teaching aids.
These models are built on wooden boxes as bases, have metal supports, and consist of strings suspended from movable arms and arranged to form a variety of geometrical figures. The strings are held in place by lead weights that are concealed by the bases. The models illustrate such things as the intersection of two half cones, the intersection of a plane, hyperbolic paraboloid and a hyperboloid of one sheet, and the intersection of two half cylinders.
Other institutions in the United States such as the Columbia School of Mines also purchased models from Olivier while Princeton had copies of Olivier's models made for them. In 1849 Olivier presented a full set of the range of models he had created to the Conservatoire National des Arts et Métiers. The models had been manufactured by the firm of Pixii, Père et Fils, and later by the firm of Fabre de Lagrange which took over their manufacture. In 1857, four years after Olivier died, Harvard University purchased 24 of Olivier's models from Fabre de Lagrange and after the university received the order Benjamin Peirce gave a series of lectures on the mathematics which they illustrated. These models are still in Harvard's collection of scientific instruments.
Even after giving a complete set of his models to the Conservatoire National des Arts et Métiers, forty models were still in Olivier's possession at the time of his death. These were sold in 1869 to William Gillispie from Union College in Schenectady, east-central New York, United States. Gillispie exhibited the models at Union College which was appropriate since, twenty years earlier, Union College had became one of the first liberal arts colleges in the United States to give engineering courses. When Gillispie died Olivier's models were sold to the college. *SAU


1872 Charles-Eugène Delaunay (9 April 1816 – 5 August 1872) French mathematician and astronomer whose theory of lunar motion advanced the development of planetary-motion theories. After 20 years of work, he published two volumes on lunar theory, La Théorie du mouvement de la lune (1860,1867). This is an important case of the three body problem. Delaunay found the longitude, latitude and parallax of the Moon as infinite series. These gave results correct to 1 second of arc but were not too practical as the series converged slowly. However this work was important in the beginnings of functional analysis. Delaunay succeeded Le Verrier as director of the Paris Observatory in 1870 but two years later he and three companions drowned in a boating accident.*TIS



1910 Julius Petersen (16 June 1839, Sorø, West Zealand – 5 August 1910, Copenhagen) was a Danish mathematician who worked on geometry and graph theory. He is best remembered for the Petersen graph. *SAU  In the mathematical field of graph theory, the Petersen graph is an undirected graph with 10 vertices and 15 edges. It is a small graph that serves as a useful example and counterexample for many problems in graph theory. The Petersen graph is named for Julius Petersen, who in 1898 constructed it to be the smallest bridgeless cubic graph with no three-edge-coloring. Although the graph is generally credited to Petersen, it had in fact first appeared 12 years earlier, in a paper by A. B. Kempe (1886). Donald Knuth states that the Petersen graph is "a remarkable configuration that serves as a counterexample to many optimistic predictions about what might be true for graphs in general."  *Wik

One of the remarkable things about the Petersen graph is that is the smallest hypohamiltonian graph -- it has no Hamiltonian cycle, but deleting any vertex makes it Hamiltonian. In less formal terms, it's possible to start at any node and visit all 10 nodes while traveling on line segments alone, but there's no way to close the loop and return to the starting node at the end of the trip; but if you remove one vertex, any of them, then it is possible to connect every node in a complete circuit.  This fact seems to have first been discovered by  René Sousselier in 1963.  




1957 Heinrich Otto Wieland (4 June 1877 – 5 August 1957) was a German chemist. He won the 1927 Nobel Prize in Chemistry for his research into the bile acids.

German chemist, winner of the 1927 Nobel Prize for Chemistry for his studies of steroid chemistry in which he determined the molecular structure of bile acids. He is also noted for studying the conversion of food into energy. In 1912, he began work on bile acids, secretions of the liver known for the best part of a century to consist of a large number of substances. He studied three of them: cholic acid, deoxycholic acid, and lithocholic acid, finding that they were all steroids, very similar to each other, and all convertible into cholanic acid. After 1921, he studied some curious alkaloids including toxiferin (curare's active ingredient), bufotalin (in venom from toads), and phalloidine and amatine (poisonous ingredients in the deadly amanita mushroom). *TiS



1981 Jerzy Neyman, (April 16, 1894 – August 5, 1981) in a paper with his long-time friend and colleague Elizabeth Scott, wrote:

Each morning before breakfast every single one of us approaches an urn filled with white and black balls. We draw a ball. If it is white, we survive the day. If it is black, we die. The proportion of black balls in the urn is not the same for each day, but grows as we become older ... Still there are always some white balls present, and some of us continue to draw them day after day for many years.

On this date, Neyman, age 87, drew a black ball. As he wished of many of his friends, “May the earth rest lightly on him.” [From a review, by Robert V. Hogg, of Neyman—From Life, by Constance Reid (Springer, 1983), in the The College Mathematics Journal, 15(1984), 82–84]*VFR
Neyman was a Russian-American mathematician who was one of the principal architects of modern theoretical statistics. His papers on hypothesis testing (1928-33) helped establish the subject. During 1934-38, he gave a theory of confidence intervals (important in the analysis of data); extended statistical theory to contagious distributions, (for interpretation of biological data); wrote on sampling stratified populations (which led to such applications as the Gallup Poll); and developed the model for randomised experiments (widely relevant across the fields of science, including agriculture, biology, medicine, and physical sciences). His later research applied statistics to meteorology and medicine. In 1968 he was awarded the prestigious National Medal of Science.*TIS



1985 Mary P. Dolciani Halloran, noted writer of several High School texts, of Hunter College died at the age of 62. The MAA book series Dolciani Mathematical Expositions is named in her honor. *VFR

Dolciani earned her Bachelor of Arts degree (B.A.) at Hunter College in New York City, and she completed her Doctor of Philosophy (Ph.D.) degree at Cornell University in 1947 with B. W. Jones as thesis advisor. She taught briefly at Vassar College before returning to Hunter, where she spent the next forty years. Dolciani taught mathematics there, and at times, she also served as a Dean or the Provost.

Although Dolciani is not well known by the general public, she was influential in developing the basic modern method used for teaching basic algebra in the United States (called "Dolciani algebra", which teaches it on the basis of drill like arithmetic, rather than on the basis of proofs as in Euclidean geometry). Dolciani also popularized the short-form names of the Properties that are familiar to many high school algebra students, e.g. the "Zero Property". *Wik




1986 Banesh Hoffmann,(September 6, 1906 - August 6, 1986) a physicist, mathematician and author who was a colleague and biographer of Albert Einstein.

In 1935, Mr. Hoffmann joined the Institute for Advanced Study in Princeton, N.J., where he worked with Einstein and a Polish physicist, Leopold Infeld, on a paper, "Gravitational Equations and the Problem of Motion."
While at Oxford, he was invited to go to Princeton and work as research associate to Dr. Oswald Veblen, a mathematics professor. In 1932, he received a doctorate in mathematics and physics from Princeton.
Mr. Hoffman worked as instructor at the University of Rochester from 1932 until 1935 and joined the faculty of Queens College in 1937. He rose to full professor and retired in the late 70s.
Hoffmann had been for the last quarter-century perhaps the best-known critic of multiple-choice testing. In his 1962 book The Tyranny of Testing and other writings, Mr. Hoffmann vehemently opposed standardized tests as superficial measures of a person`s knowledge. He died August 6, 1986 at his home in Flushing, N.Y. He was 79. *Sun Sentinal Obituary





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