Wednesday 24 April 2024

Pythagorean Parabolas

 


I recently came across a note on an Annual Meeting of the Rocky Mountain Section of the MAA in 1923. Among the list of presentations was one by W. J. Hazzard, Professor at the Colorado School of Mines on the topic of "Parabolic Grouping of Pythagorean triangles."
I was a little familiar with Prof. Hazard as I had leapfrogged off one of his old posts in the Mathematics Teacher on methods of solving a quadratic equation to write a little about the history of solving quadratics in twenty or so different ways, which I hope someday to reduce to blog posts, but not today. 
I even had a copy of one of the good Professor's books in my collection of old math books, but I had not read, nor was I aware of the idea he spoke of.  With a few words of guidance from a "very" brief coverage in the article, I was able to extract at least a little that may be of interest to anyone who enjoys Pythagorean relations, and especially if you teach high school math.

If you put one acute vertex of a right triangle at the origin and lay it out so that the shorter leg lies along the positive x-axis, the other vertex will be at the point (a,b) as determined by the two legs of the triangle.  In the graph I have shown the  position of a 3-4-5 triangle and a 5-12-13 triangle to make my meaning clear.

A natural question is, "So What?"  But if we look at several of the points determined by the upper vertex, and select out only some "related" Pythagorean triples, we notice a pattern.  In the image at right the points represent the set of triples 3-4-5; 5-12-13; 7-24-25; and 9-40-41.  (Any teacher or student who is not aware, there is a simple trick to find an infinite number of these triangles with a longer side one less than the hypotenuse.  Just take any odd number to be the short leg, square it, and then divide by two and round up to the next whole for the hypotenuse. For example, 11 is a good odd number, and its square is 121.  If we divide 121 by 2 we get 60.5, which is between 60 and 61, and 11, 60, 61 is a Pythagorean triple.) 
All the points lie on a parabola y= 1/2 x2 - 1/2 .  Since the focal length is 1/(4A), with A = 1/2, the focus must be a distance of 1/2 unit above the vertex, making the focal point at the origin. If we think about the definition of a parabola as the set of points equally distant from a focus and directrix, we realize the line of the directrix must be the line y = -1 so that, for instance the point (3,4) which is 5 units from the origin/focus will also be 5 units away from the directrix.  

Admittedly that is a pretty small (although infinity large) sub-set of the Pythagorean triples.  What would happen if we plotted other triangles like 8-15-17?  It turns out they are not on the parabola drawn... they are on another one.  In fact, all the triangles which have a longer leg two less than the hypotenuse will also have a focus at the origin, and the directrix will be ... yeah you knew it would be, y = - 2.  That makes the focus at (0,-1).   You can write the equation with ease for the parabola passing through any of these Pythagorean vertices, and all the ones with a common difference between the longer leg and hypotenuse share a parabola.

All the triples I've picked so far have been primitive triples.  A good question to ask is what would happen if we picked, say, a 6-8-10 triangle. Will it fall on the same parabola as the 3-4-5, or on the ones with a difference of two?

The image below shows parabolas for differences of 1, 2, and 8 between the longer side and hypotenuse, and point D is the 6-8-10 triangle, right there with 8-15-17 and others like it. 





I'm not sure you can swap this information for bread or ale at the local inn, but it's pretty interesting stuff.

On This Day in Math - April 24

  




Simplicibus itaque verbis gaudet Mathematica Veritas, cum etiam per se simplex sit Veritatis oratio.
(So Mathematical Truth prefers simple words
since the language of Truth is itself simple.)

~ Tycho Brahe


The 114th day of the year; this day begins a string of thirteen consecutive day numbers that are composite. There is no string of more composite year day numbers. The next such string of composite day numbers will include Halloween.

The sum of the first 114 digits of e after the decimal point, is prime. This is the third consecutive day number with this property.

114 is another of D R Kaprekar's Harshad (Joy-Giver) numbers, divisible by the sum of its digits.  Remembering that the famous Taxicab number of Ramanujan and Hardy, is also a Harshad number makes it easy to factor, since 1 + 7 + 2 + 9 = 19 is a factor.

114 is the sum of the first four hyperfactorials starting with zero, 0^0 + 1^1 + (2^2)(1^1) + (3^3)(2^2)(1^1) = 1+1+4+108 = 114.


The largest gap between two consecutive six digit primes is 114.

********Find more of these at Math Day of the Year Facts. *********************




EVENTS


1066 Halley's Comet heralded an invasion when it appeared over England. A monk spotted it and predicted the destruction of the country. The monk, Eilmer of Malmesbury (also known as Oliver due to a scribe's miscopying, or Elmer) was an 11th-century English Benedictine monk best known for his early attempt at a gliding flight using wings. He seems to have predicted the destruction of England when he saw the comet and wrote, "You've come, have you? – You've come, you source of tears to many mothers. It is long since I saw you; but as I see you now you are much more terrible, for I see you brandishing the downfall of my country." William of Malmesbury, who provides almost all the known information about Eilmer, writes that, in Eilmer's youth, he had read and believed the Greek fable of Daedalus. Thus, Eilmer fixed wings to his hands and feet and launched himself from the top of a tower at Malmesbury Abbey.*Wik (well, he got the invasion part right)





1610 Galileo comes to demonstrate his telescope but is poorly received.
from a Letter from Martin Horky to Kepler, April, 1610

Galileo Galilei, the mathematician of Padua, came to us in Bologna and he brought with him that spyglass through which he sees four fictitious planets. On the twenty-fourth and twenty-fifth of April I never slept, day and night, but tested that instrument of Galileo's in innumerable ways, in these lower as well as the higher [realms]. On Earth it works miracles; in the heavens it deceives, for other fixed stars appear double. Thus, the following evening I observed with Galileo's spyglass the little star that is seen above the middle one of the three in the tail of the Great Bear, and I saw four very small stars nearby, just as Galileo observed about Jupiter. I have as witnesses most excellent men and most noble doctors, Antonio Roffeni, the most learned mathematician of the University of Bologna, and many others, who with me in a house observed the heavens on the same night of 25 April, with Galileo himself present. But all acknowledged that the instrument deceived. And Galileo became silent, and on the twenty-sixth, a Monday, dejected, he took his leave from Mr. Magini very early in the morning. And he gave no thanks for the favors and the many thoughts, because, full of himself, he hawked a fable. Mr. Magini provided Galileo with distinguished company, both splendid and delightful. Thus the wretched Galileo left Bologna with his spyglass on the twenty-sixth.

Beneath the letter in German he has written, "Unknown to anyone, I have made an impression of the spyglass in wax, and when God aids me in returning home, I want to make a much better spyglass than Galileo's." *Timothy J. McGrew, Western Michigan Univ.

Len Fisher ‏@LenFisherScienc sent a clip that pointed out that Galileo's fellow Pisano, was one of those who refused to look through the glass at all:

*from "Weighing the Soul"


1676 In a letter to the Royal Society, Leeuwenhock describes what happens after he put pepper water in his study for three weeks and then observed it through his scope, "I looked upon it the 24th of April, 1676 and discerned to my great wonder, an incredible number of very small animals of divers kinds." *Lisa Jardine, Incredible Pursuits, pg 92

HT to Greg Priest

1800 The Library of Congress established . $5000 was appropriated for the purchase of such books as may be necessary for the use of Congress at the said city of Washington and for filling up a suitable apartment for containing them and for placing them therein." The first catalog, dated April 1802, listed 964 volumes and 9 maps. *VFR


In 1851, the first engineering society of importance in the U.S. was incorporated. The Boston Society of Civil Engineers was organized at an informal meeting on 26 Apr 1848, and its first regular meeting was held 3 Jul 1848. Its purpose was "promoting science and instruction in the department of civil engineering." In the following year, the national American Society of Civil Engineers and Architects was founded on 5 Nov 1852 in New York City. Earlier attempts in the U.S. to sustain an engineering society were unsuccessful, including those by the engineers of the Cincinnati & Charleston Railroad in 1836; engineers in Baltimore, Md. in 1839; and a society in Albany, N.Y. in 1841.





1897 The Chicago Section of the American Mathematical Society held its organizational meeting in Chicago under the chairmanship of E. H. Moore. It was the first section of the AMS. [Cajori, Historical Introduction to the Mathematical Literature, p. 34] *VFR

E H Moore



In 1925, Darwin's theory of evolution was reputed to be taught in Dayton, Tennessee, by teacher John Scopes, who used the high school textbook, Civic Biology by George Hunter. For this, Scopes, 24, was prosecuted under the Butler Act, a state law enacted in the previous month, on 21 Mar 1925. It prohibited the teaching of evolution in public schools. The trial , which began 10 Jul 1925) was used as a platform to challenge the legality of the statute. Scopes was supported by the American Civil Liberties Union. At its end, on 21 Jul 1925, Scopes was convicted and fined $100. On appeal, the state supreme court upheld the constitutionality of the 1925 law but acquitted Scopes on the technicality that he had been fined excessively. The law was not repealed until 17 May 1967. *TIS 

 the Butler Act was passed in Tennessee, on March 25, 1925. Butler later stated, "I didn't know anything about evolution ... I'd read in the papers that boys and girls were coming home from school and telling their fathers and mothers that the Bible was all nonsense." Tennessee governor Austin Peay signed the law to gain support among rural legislators, but believed the law would neither be enforced nor interfere with education in Tennessee schools.William Jennings Bryan thanked Peay enthusiastically for the bill: "The Christian parents of the state owe you a debt of gratitude for saving their children from the poisonous influence of an unproven hypothesis."  The Tennessee college in Clarksville is named for Governor Peay.  

It would remain the law in Tennessee until repealed on September 1, 1967. *Wik





In 1928, the fathometer was patented by Herbert Grove Dorsey (No. 1,667,540). His invention was an electro-mechanical sounding instrument that measured underwater depths by using a series of electrical sounds signals and their echoes. He coined the name fathometer. The same instrument could measure both very shoal water and very deep water. His fathometers not only improved hydrographic surveying but also were valuable to the maritime shipping industry by saving time over line soundings. His instruments helped delineate much of the continental shelf and slope of the United States and its territories as well as much of the deep sea, in particular the northeast Pacific Ocean, the mid-Atlantic shelf and slope, and Gulf of Mexico.*TIS

Dorsey and his fathometer




A model of 1862 Apollo viewed from the pole (top) and from the equator (bottom). The irregular shape of asteroids like 1862 Apollo means that photons adsorbed and re-emitted from the surface can produce a net torque that gradually makes the asteroids spin faster – what is known to astronomers as the "YORP" effect. Image credit: Mikko Kaasalainen and Josef Durech

1932 Minor Planet Apollo Discovered on April 24 by K. Reinmuth at Heidelberg. This object is named for the god of the Sun. Patrick Poitevin ‏@PatrickPoitevin
The prototype asteroid of the Apollo group. In 1932 it approached Earth to within 10.5 million km (0.07 AU), but was then lost until 1973. Apollo can come as close to Earth as 4.2 million km (0.028 AU) and also make near passes of Venus and Mars, whose orbits it crosses at perihelion and aphelion,respectively.*http://www.daviddarling.info


1949 Columbia issued a stamp honoring the mathematician Julio Garavito Armero (1865{1920). [Scott #573] *VFR [He is also on the 20,000 peso bank note] As an astronomer of the observatory, he did many useful scientific investigations such as calculating the latitude of Bogotá, studies about the comets which passed by the Earth between 1901 and 1910 (such as Comet Halley), and the 1916 solar eclipse (seen in the majority of Colombia). But perhaps the most important were his studies about celestial mechanics, which finally turned into studies about lunar fluctuations and their influence on weather, floods, polar ice, and the Earth's orbital acceleration (this was corroborated later). He worked also in other areas such as optics (this work was left unfinished at his death), and economics, by which he helped the country recover from the rough civil war. With this objective, he gave lectures and conferences in economics and the human factors which affected it, such as war or overpopulation. *Wik


1980 The winning number in the Pennsylvania lottery was 666. On this day a group of men bet some $20,000 on all combinations involving just 4 and 6. The state lost two million. In 1982 two men were convicted of a lottery fix. Ironically, on the day they went to prison, Delaware's daily number came up 555.




1981 first IBM personal computer was introduced.IBM's own Personal Computer (IBM 5150) was introduced in August 1981, only a year after corporate executives gave the go-ahead to Bill Lowe, the lab director in the company's Boca Raton, Fla., facilities. He set up a task force that developed the proposal for the first IBM PC. Early studies had concluded that there were not enough applications to justify acceptance on a broad basis and the task force was fighting the idea that things couldn't be done quickly in IBM. One analyst was quoted as saying that "IBM bringing out a personal computer would be like teaching an elephant to tap dance." During a meeting with top executives in New York, Lowe claimed his group could develop a small, new computer within a year. The response: "You're on. Come back in two weeks with a proposal." *IBM


1981 Apple Computer introduces its Apple IIc, a portable machine designed to have the same operating capacity as the standard IIe model. The machine came with 128 kilobytes of RAM and a 5 1/4 inch floppy disk drive. *CHM    Perfect for its time! *PB




In 1990, space shuttle Discover was launched from Cape Canaveral, carrying the Hubble Space Telescope to be placed into orbit. *TIS   The following day (4/25/90) the Hubble telescope would be deployed from Discoverer into orbit.  It would be almost another month (5/20/90) before the first image ("first light")  shows the 50% sharper images than Earth based images. 

The image is of the 1/4 sized replica on the courthouse lawn in Hubble's birthplace, Marshfield Missouri.




BIRTHS

1562 Xu Guang-qi ( April 24, 1562 - November 8, 1633 ,aged 71) was a Chinese mathematician who made Western mathematics available by translating works into Chinese. *SAU

Xu Guangqi with Matteo Ricci (left) From Athanasius Kircher's China Illustrata, 1667




1620 John Graunt(24 April 1620 – 18 April 1674)His book Natural and Political Observations Made upon the Bills of Mortality (1662) used analysis of the mortality rolls in early modern London as Charles II and other officials attempted to create a system to warn of the onset and spread of bubonic plague in the city. Though the system was never truly created, Graunt's work in studying the rolls resulted in the first statistically-based estimation of the population of London. It was his only book but it was the foundations of both statistics and demography. *VFR [A nice essay on his "Bills of Mortality" and life is at the Rice University Stats Page by Thompson. Some personal history is at The Renaissance Mathematicus





1750 Simon Antoine Jean Lhuilier (24 April 1750 in Geneva, Switzerland - 28 March 1840 in Geneva, Switzerland) His work on Euler's polyhedra formula, and exceptions to that formula, were important in the development of topology. Lhuilier also corrected Euler's solution of the Königsberg bridge problem. He also wrote four important articles on probability during the years 1796 and 1797. His most famous pupil was Charles-François Sturm who studied under Lhuilier during the last few years of his career in Geneva. *SAU He won the mathematics section prize of the Berlin Academy of Sciences for 1784 in response to a question on the foundations of the calculus. The work was published in his 1787 book Exposition elementaire des principes des calculs superieurs. It was in this book that he first introduced the "lim." (the period would soon fall out use) notation for the limit of a function. he wrote, "lim.\( \frac{\delta x}{\delta x} \). The symbol reappeared in 1821 in Cours d'Analyse by Augustin Louis Cauchy. *Florian Cajori, The History of Notations on the Calculus.





1863 Giovanni Vailati (24 April 1863 – 14 May 1909) was an Italian proto-analytic philosopher, historian of science, and mathematician. Vailata's main historical interests concerned mechanics, logic, and geometry, and he was an important contributor to a number of areas, including the study of post-Aristotelian Greek mechanics, of Galileo's predecessors, of the notion and rôle of definition in the work of Plato and Euclid, of mathematical influences on logic and epistemology, and of the non-Euclidean geometry of Gerolamo Saccheri. He was particularly interested in the ways in which what might be seen as the same problems are addressed and dealt with at different times.
His historical work was interrelated with his philosophical work, involving the same fundamental views and methodology. Vailati saw the two as differing in approach rather than subject matter, and believed that there should be co-operation between philosophers and scientists in the pursuit of historical studies. He also held that a complete history demanded that one take into account the relevant social background. *Wik




1899 Oscar Zariski (24 April 1899 in Kobrin, Russian Empire (now Belarus) - 4 July 1986 in Brookline, Massachusetts, USA) Zariski's work was on foundations of algebraic geometry using algebraic methods. He worked on the theory of normal varieties, local uniformisation and the reduction of singularities of algebraic varieties. *SAU


1919 David H. Blackwell (April 24, 1919 – July 8, 2010) American Statistician, President of the Institute of Mathematical Statistics. Many more honours were to come his way. He was elected Vice President of the American Statistical Association, Vice President of the International Statistical Institute, and Vice President of the American Mathematical Society. In 1965 he was elected to the National Academy of Sciences. He received the John von Neumann Theory Prize from the Operations Research Society of America in 1979 for his work in dynamic programming and the R A Fisher Award from the Committee of Presidents of Statistical Societies in 1986.*SAU
and a nice links for more information, with thanks to Dave Bee:
For the extensive “An Oral History With David Blackwell”, conducted by Nadine Wilmot in 2002 and 2003.




1947 Ovide Arino (24 April 1947 - 29 September 2003) mathematician working on delay differential equations. His field of application was population dynamics. He was a quite prolific writer, publishing over 150 articles in his lifetime. He also was very active in terms of student supervision, having supervised about 60 theses in total in about 20 years. Also, he organized or coorganized many scientific events. But, most of all, he was an extremely kind human being, interested in finding the good in everyone he met. *euromedbiomath.com


DEATHS

1572 Petrus Ramus (1515, 24 Apr 1572 [Wik gives his death on 26 August]).
(Pierre de La Ramée) French mathematician and logician who challenged Aristotelian philosophy. As early as in his Master of Arts thesis (1536) he held that quaecumque ab Aristotle dicta essent, commentitia esse ("everything which Aristotle said is invented or contrived"). His book Aristotelicae animadversiones (1543) led to a decree from Francis I (Mar 1544) prohibiting such teachings. Though the decree was rescinded three years later by Henry II, Ramus continued to draw hostility from other scholars. He was an early adherent of the Copernican system. Ramus was murdered during the St. Bartholomew's Day massacre, but his theories remained influential after his death. *TIS




1656 Thomas Fincke (6 January 1561 – 24 April 1656) was a Danish mathematician and physicist, and a professor at the University of Copenhagen for more than 60 years. His lasting achievement is found in his book Geometria rotundi (1583), in which he introduced the modern names of the trigonometric functions tangent and secant.
His son in law was the Danish physician and natural historian, Ole Worm, who married Fincke's daughter Dorothea.*Wik

 His most famous book Geometriae rotundi (1583), was intended as a textbook. Based on works of Ramus from whom he took the word 'radius', the book introduces the terms 'tangents' and 'secants' and Fincke devised new formulae such as the law of tangents.

Fincke's book was recommended by Clavius, Napier and Pitiscus all of whom adopted much from it. His other books on astronomy and astrology are of much less interest despite the fact that he was in touch with Brahe and Kepler. *SAU







1952 Hendrik Anthony Kramers (17 Dec 1894 - 24 Apr 1952 at age 57)Dutch physicist who, with Ralph de Laer Kronig, derived important equations relating the absorption to the dispersion of light. He also predicted (1924) the existence of the Raman effect, an inelastic scattering of light. Kramer's work covers almost the entire field of theoretical physics. He published papers dealing with mathematical formalism of quantum mechanics, and others on paramagnetism, magneto-optical rotation, ferro-magnetism, kinetic theory of gases, relativistic formalisms in particle theory, and on theory of radiation. His work shows outstanding mathematical skill and careful analysis of physical principles. *TIS

He worked with Niels Bohr to understand how electromagnetic waves interact with matter and made important contributions to quantum mechanics and statistical physics. *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

Tuesday 23 April 2024

On This Day in Math - April 23

 


"Whatever is worth saying,
can be stated in fifty words or less"
~ Stanislaw Ulam *bt (before twitter)

Thanks to @cytiaB for this one



The 113th day of the year; 113 is prime, its reversal (311) is prime, and the number you get by any reordering of its digits is still prime. Students might try to find other of these "absolute" or "permutable" primes.

Also the sum of the first 113 digits of e is prime. That was also true of yesterday's number, and tomorrow's. (I was just wondering to myself, what is the longest known string of consecutive n for which the first n digits of e are prime? And a similar question for pi? "Anyone...anyone??? Bueller???)

355 is almost exactly \(113 \pi = 354.9999699.. \) No year day is closer,


This is the only solution to a² + b³ = c⁷ in positive integers *Fermat's Library



There are 13 consecutive divisible integers (non-primes) between 113 and 127. How far until the next streak as long, or longer?

********Find more of these at Math Day of the Year Facts. *********************



EVENTS

1635 The 1st public school in the United States, Boston Latin School, was founded. It is still enrolling students. *George Costanza

1827 Sir William Hamilton presented his Theory of Systems of Rays at the Royal Irish Academy in Dublin. Although he was still an undergraduate, only 21 years old, his work is one of the important works in optics, for it provided a single function that brings together mechanics, optics and mathematics. It led to establishing the wave theory of light, which gives that light is a form of energy that travels in waves. *TIS  In it he begins by proving that a system of light rays filling a region of space can be focused down to a single point by a suitably curved mirror if and only if those light rays are orthogonal to some series of surfaces. Moreover, the latter property is preserved under reflection in any number of mirrors. Hamilton’s innovation was to associate with such a system of rays a characteristic function, constant on each of the surfaces to which the rays are orthogonal, which he employed in the mathematical investigation of the foci and caustics of reflected light.






1867, the Zoetrope was patented by William E. Lincoln of Providence, R.I. (No. 64,117). The device was the first animated picture machine. It provided an animation sequence of pictures lining the inside wall of a shallow cylinder, with vertical slits between the images. By spinning the cylinder and looking through the slits, a repeating loop of a moving image could be viewed.




 In 1896, the first movie shown to a paying theatre audience in the U.S. was presented using Thomas Edison’s Vitascope. The movie had a series of short scenes, and were part of a program with other acts at Koster and Bial’s Music Hall, 34th St, New York City. Included in the film shorts were a ballet scene, a burlesque boxing match, waves on a sea shore, and a comic allegory The Monroe Doctrine,all of which were projected at about half life size.





1906 First American automobile meets the first American speed bump. In March of 1906, residents of Chatham Borough, New Jersey had begun construction of a speed control device, crosswalks that were five Inches high, constructed of flagstones and cobblestones. Their creation was a plan to slow down the "very fast pace" (10-15 miles per hour) of the new motor carriages that have begone to take over the roads of the center of town. On "April 22, 1906 with great fanfare and many spectators. Bystanders set up seating and vendors sold hot dogs and pop corn to serve the growing group of onlookers. The next day local newspapers reported on the wreckage and carnage from the newly discovered speed reducers." Here is the article from the New York Times on April 23:
There were several persons in the machine, and when the heavy rubber tires struck the elevation there was a palpitation of the machinery and the car shot up several feet in the air. Goggles, hats, a monkey wrench, sidecombs, hairpins and other articles flew in all directions. The crowd gave a cheer and decided the borough’s plan was effective. The ‘bumps' installed by the borough officials of the village of Chatham to check the speed of automobiles through the village had their first test yesterday, and proved a decided success.
 The more conventional speed bumps we are familiar with were not invented until June of 1953.  They were created by Nobel Prize winning physicist, Arthur Holly Compton, while  he was Chancellor of Washington University in St. Louis, Missouri. *Quora.Com, Wik




 1948 Contract signed by A. Nielsen for UNIVAC I. The UNIVAC I (UNIVersal Automatic Computer I) was the first commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC. Design work was begun by their company, Eckert-Mauchly Computer Corporation, and was completed after the company had been acquired by Remington Rand. (In the years before successor models of the UNIVAC I appeared, the machine was simply known as "the UNIVAC".) The image is not the computer, but the operators console... (no mouse for that monster)
The first UNIVAC was delivered to the United States Census Bureau on March 31, 1951, and was dedicated on June 14 that year. The fifth machine (built for the U.S. Atomic Energy Commission) was used by CBS to predict the result of the 1952 presidential election. With a sample of just 1% of the voting population it correctly predicted that Dwight Eisenhower would win. The UNIVAC I computers were built by Remington Rand's UNIVAC division (successor of the Eckert-Mauchly Computer Corporation, bought by Rand in 1950 which later became part of Sperry, now Unisys). *Wik

In 1962, the first American satellite to reach the moon surface, the Ranger IV, was launched at 3:50pm from Cape Canaveral, Florida. As intended, it impacted on the moon three days later at 7:50pm on 26 Apr, travelling at 5,963 mph. The launch vehicle was an Atlas-Agena B rocket, 102 feet high, 16 feet in diameter at the base. The distance the satellite would travel was about 229,541 miles. *TIS

1964 SEAC Computer Retired:
The National Bureau of Standards retires its SEAC (Standards Eastern Automatic Computer), which it built in Washington 15 years earlier as a laboratory for testing components and systems for setting computer standards. The SEAC was the first computer to use all-diode logic, a technology more reliable than vacuum tubes, and the first stored-program computer completed in the United States. Magnetic tape in the external storage units stores programming information, coded subroutines, numerical data, and output.*CHM

1973 The US issued a commemorative stamp honoring the 500th year of the birth of Copernicus who wrote the  De Revolutionibus.

In 1994, physicists at the Department of Energy's Fermi National Accelerator Laboratory discovered the subatomic particle called the top quark.*TIS  A quark is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei.  

For some time, Gell-Mann was undecided on an actual spelling for the term he intended to coin, until he found the word quark in James Joyce's 1939 book Finnegans Wake:

– Three quarks for Muster Mark!
Sure he hasn't got much of a bark
And sure any he has it's all beside the mark.

The word quark is an outdated English word meaning to croak and the above-quoted lines are about a bird choir mocking king Mark of Cornwall in the legend of Tristan and Iseult.  
Another explanation by some, Especially in the German-speaking parts of the world there is a widespread legend, however, that Joyce had taken it from the word Quark, a German word of Slavic origin which denotes a curd cheese, but is also a colloquial term for "trivial nonsense". *Wik




2012 An active sunspot period leads to incredible aurora in US Midwest. The aurora borealis put on a dazzling show in more than a dozen states Monday night, according to SpaceWeather.com.
A particularly spectacular display was seen in Fergus Falls in western Minnesota, and Douglas Kiesling was on hand to film a stunning time-lapse video of the event,


BIRTHS

1628 Johann Hudde was a Dutch mathematician who worked on maxima and minima and the theory of equations. He gave an ingenious method to find multiple roots of an equation. He worked on improving the algebraic methods of René Descartes, seeking to extend them to the solution of equations of a higher degree by applying an algorithm. He also developed an algorithm based on Fermat's method to deal with the maxima, minima and tangents to curves of algebraic functions. Later, he served as burgomaster of Amsterdam for 30 years. During this time time he made a mathematical study of annuities. Hudde continued with an interest in physics and astronomy, producing lenses and microscopes. He collaborated with Baruch Spinoza, of Amsterdam, on telescopes. Hudde determine that in a telescope, a plano-convex lenses were better than concavo-convex. *TIS He is buried in #58 in the high choir of the Oude kerk (old church) in Amsterdam. (Help, send pictures please?) Unfortunately, Donovan Carroll informed me that his stone is covered over by the choir loft. More about Hudde and the "lost calculus" here.  And the Renaissance Mathematics has a nice article about Hudde's circle of associates that is both political and mathematical, and involves a violent murder....



1743 Samuel Williams (23 Apr 1743; 2 Jan 1817 at age 73) American natural philosopher and clergyman who organized the first expedition of its kind in the U.S. (departing on 9 Oct 1780) to observe a total solar eclipse in Penobscot Bay, Maine, although it was held by the British enemy. The eclipse was very slightly less than being total, and he is believed to be the first to observe the “ Baily's Beads” phenomenon seen along the sun's last sliver. Previously, with John Winthrop (under whom he studied) he travelled to St. John's, Newfoundland (1761) to observer the Transit of Venus. When Wintrop died, Williams succeeded him (1779) as the Hollis Professor of Mathematics and Natural Philosophy at Harvard University. He researched and taught astronomy, meteorology, and magnetism. He resigned in June 1788. He also engaged in state boundary surveys: NY and Mass. (1785-88), and Vermont and Canada (1795).*TIS

The Baily's beads, diamond ring or more rarely double diamond ring effects,[1] are features of total and annular solar eclipses. Although caused by the same phenomenon, they are distinct events during these types of solar eclipses. As the Moon covers the Sun during a solar eclipse, the rugged topography of the lunar limb allows beads of sunlight to shine through in some places while not in others. They are named for Francis Baily, who explained the effects in 1836.[2][3] The diamond ring effects are seen when only one or two beads are left, appearing as shining "diamonds" set in a bright ring around the lunar silhouette.*Wik

*Linda Hall Org






1853 Alphonse Bertillon (23 Apr 1853, 13 Feb 1914 at age 60) French criminologist who was chief of criminal identification for the Paris police from 1880. He developed an identification system known as anthropometry, or the Bertillon system, that came into wide use in France and other countries. The system records physical characteristics (eye colour, scars, deformities, etc.) and specified measurements (height, fingertip reach, head length and width, ear, foot, arm and finger length, etc) These are recorded on cards and classified according to the length of the head. After two decades this system was replaced by fingerprinting in the early 1900s because Bertillon measurements were difficult to take with uniform exactness, and could change later due to growth or surgery. *TIS



1856 Granville Tailer Woods (April 23, 1856 – January 30, 1910) was an American inventor who held more than 50 patents in the United States. He was the first African American mechanical and electrical engineer after the Civil War. Self-taught, he concentrated most of his work on trains and streetcars. One of his inventions is the Synchronous Multiplex Railway Telegraph, a variation of the induction telegraph that relied on ambient static electricity from existing telegraph lines to send messages between train stations and moving trains.
Granville T. Woods invented and patented Tunnel Construction for the electric railroad system and was referred to by some as the "Black Edison". Over the course of his lifetime, Granville Woods obtained more than 50 patents for inventions including an automatic brake and an egg incubator and for improvements to other technologies such as the safety circuit, telegraph, telephone, and phonograph.*Wik






1858 Max Planck, (April 23, 1858 – October 4, 1947)  German physicist, born. He studied at Munich and Berlin, where he studied under Helmholz, Clausius and Kirchoff and subsequently joined the faculty.he became professor of theoretical physics (1889-1926). His work on the law of thermodynamics and the distribution of radiation from a black body led him to abandon classical Newtonian principles and introduce the quantum theory (1900), for which he was awarded the Nobel Prize for Physics in 1918. This assumes that energy is not infinitely subdivisible, but ultimately exists as discrete amounts he called quanta (Latin, "how much"). Further, the energy carried by a quantum depends in direct proportion to the frequency of its source radiation.*TIS



1910 Sheila Scott Macintyre (née Sheila Scott, April 23, 1910 - March 21, 1960) was a Scottish mathematician well known for her work on the Whittaker constant.(The constant isn't actually a known constant, but is known to be in a small interval.  Macintyre lowered the upper bound and reduced the interval of uncertainty by about 10%).  Macintyre is also well known for creating a multilingual scientific dictionary: written in English, German, and Russian; at the time of her death, she was working on Japanese.*Wik



1911 Felix Adalbert Behrend (23 April 1911 in Charlottenburg, Berlin, Germany -27 May 1962 in Richmond, Victoria, Australia) Behrend studied number theory for his doctorate at the University of Berlin with Erhard Schmidt as his advisor. He was awarded his doctorate in 1933 for his dissertation Über numeri abundantes. Even before the award of his doctorate he had published three papers on number theory, the first two being Über einen Satz von Herrn Jarnik (1932) and Über numeri abundantes (1932). Of course 1933, the year that Behrend was awarded his doctorate, was also the year that Hitler came to power in Germany.
Like many Germans who fled from the Nazi threat, he found himself in England which was at war with his native Germany. He continued his work on number theory and published "On obtaining an estimate of the frequency of the primes by means of the elementary properties of the integers" in the Journal of the London Mathematical Society in 1940. The fact that he was passionately anti-Nazi did nothing to help save him from being interned as an enemy alien in 1940 and he was put on the ship the Dunera bound for Australia. He served periods of internment at Hay, Orange and Tatura in Australia. His experiences in Camp 7 at Hay during 1940-41 are related in . One should not think that internment meant an end to mathematics, for he gave lecture courses at the Camp and prepared some of his younger fellow internees for mathematics examinations at the University of Melbourne.
After his release in 1942, Behrend was appointed as a tutor at the University of Melbourne. He continued his research in number theory and published On the frequency of the primes in the Journal of the Royal Society of New South Wales in 1942. This paper was a continuation of the one he had published in London two years earlier. In the following year he published a paper on a totally different topic. This was A polyhedral model of the projective plane which also appeared in the Journal of the Royal Society of New South Wales. Behrend is commemorated by the 'Behrend memorial lecture in mathematics', established at the University of Melbourne in 1963 with funds provided by his widow. *SAU

1914 Georgii Nikolaevich Polozii (23 April 1914 in Transbaikal, Russia - 26 Nov 1968 in Kiev, Ukraine) Polozii studied at Saratov University which had been founded in 1919. He graduated in 1937 and then was appointed to the teaching staff of the university. In 1949 Polozii was appointed to the University of Kiev and he remained at Kiev until his death in 1968.
Polozii's major pure mathematical contributions were to the theory of functions of a complex variable, approximation theory, and numerical analysis. He also made major contributions to mathematical physics and applied mathematics in particular working on the theory of elasticity.

Between 1962 and 1966 Polozii developed the theory for a new class of (p,q) analytic functions.
In approximation theory Polozii worked mainly with the aim of developing effective methods to solve boundary value problems which arise in mathematical physics. He work here produced the method of summary representation.*SAU



1970 My Oldest son is born, "Happy Birthday Beau".

DEATHS

1616 Miguel de Cervantes Saavedra died and William Shakespeare both died on this date, the former in Madrid, Spain, the latter in Stratford-on-Avon, England. Which one died first? This is not a trick question; they died several days apart. All you need to solve it is some knowledge of the calendar. *VFR (Curiously, Shakespeare was also born on this date in 1564. If you see April 26th, that is date of his baptism.)


1839 The Very Reverend James Wood (14 December 1760 – 23 April 1839) was a mathematician, Dean of Ely and Master of St John's College, Cambridge.
Wood was born in Holcombe where his father ran an evening school and taught his son the elements of arithmetic and algebra. From Bury Grammar School he proceeded to St John's College, Cambridge in 1778, graduating as senior wrangler in 1782. On graduating he became a fellow of the college and in his long tenure there produced several successful academic textbooks for students of mathematics. (The Elements of Algebra (1795); The Principles of Mechanics (1796); The Elements of Optics (1798))
Wood remained for sixty years at St. John's, serving as both President (1802–1815) and Master (1815–1839); on his death in 1839 he was interred in the college chapel and bequeathed his extensive library to the college, comprising almost 4,500 printed books on classics, history, mathematics, theology and travel, dating from the 17th to the 19th centuries.[3]
Wood was also ordained as a priest in 1787 and served as Dean of Ely from 1820 until his death.{He was succeeded by another eminent mathematician, George Peacock)*Wik



1922   Laroy S. Starrett (25 Apr, 1836-23 Apr 1922) was an American inventor and manufacturer who held over 100 patents, many for fine measurement tools, including the micrometer screw guage (patented 29 Jul 1890) that is familiar to present-day machinists and physics lab workers. His first patent (23 May 1865) was for a meat chopper, which he had manufactured for him, but marketed it himself. This product was successful, and his next patents for shoe studs and hooks provided enough income to establish his own factory. He began making a combination square. This was a try-square with a head that could be moved and clamped at any position along the blade, which he patented 26 Feb 1879. He added products including rules, surface guages, and other small tools. His business became the world's largest in his specialty. When he died, it had over five acres of production space, and 1,000 workers. *TIS  The company is still making quality instruments today.  I've owned a few fine Starrett micrometers and other gauging equipment in my days.






1930 Henry Ernest Dudeney, (10 April 1857–23 April 1930)  England's greatest puzzlist. He was unusually skilled at geometrical dissections, cutting a polygon into the smallest number of pieces that can be refitted to make a different type of polygon. He was also the first to apply digital roots, a term he coined, to recreational mathematics. *VFR
In April 1930, Dudeney died of throat cancer in Lewes, where he and his wife had moved in 1914 after a period of separation to rekindle their marriage. Alice Dudeney survived him by fourteen years and died November 21, 1945, after a stroke. Both are buried in the Lewes town cemetery. Their grave is marked by a copy of an 18th century Sussex sandstone obelisk, which Alice had copied after Ernest's death to serve as their mutual tombstone.(would love a photo if anyone is in that area)
For samples of his puzzles, the Amazon Kindle edition is free.






1960 Max von Laue (9 Oct 1879, 23 Apr 1960 at age 80)German physicist who was a recipient of the Nobel Prize for Physics in 1914 for his discovery of the diffraction of X-rays in crystals. This enabled scientists to study the structure of crystals and hence marked the origin of solid-state physics, an important field in the development of modern electronics. *TIS


Norio Ohga, otherwise spelled Norio Oga (January 29, 1930 – April 23, 2011), was the former president and chairman of Sony Corporation, credited with spurring the development of the compact disc as a commercially viable audio format.
He insisted that a CD should hold 75 minutes of music, sufficient for the entire Beethoven's Ninth Symphony, which accounts for the designed 4.8-inch diameter. Having had a career as an opera singer before he joined the company in the 1950s, he remained a music connoisseur, and recognized the importance of improved sound quality made possible by the CD. Sony issued the world's first CD in 1982, and in Japan, within five years the format overtook LP record sales. He rose through the company to become its chief executive in 1989, always pursuing improvements to quality and appealing design, and led Sony's expansion from hardware to software to entertainment including music, films and video games.




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