The laws of nature are but the mathematical thoughts of God.
~Euclid
The 235th day of the year; 235 is the number of trees with 11 vertices.
(Counting the number of unlabeled free trees is still an open problem in math. No closed formula for the number of trees with n vertices up to graph isomorphism is known.)
235, like all numbers ending in 5 that are greater than 25, is the difference of two squares of integers that differ by five, 26^2 - 21^2 = 235. Like all odd numbers, it is the difference of two consecutive squares, 235 = 118^2 - 117^2.
235 is a semi-prime (5 x 47) that is the concatenation of the first three Fibonacci primes
235 is a palindrome in base 4 (32234), 7 (4547), and 8 (3538),
U-235 is the fissile isotope of uranium used in the first atomic bombs.
If you build an equilateral triangle with nine matchsticks on each side, then subdivide into additional equilateral triangles, there will be a total of 235 triangles of several different sizes. The image shows the subdivision of a equilateral triangle with three matchsticks on a side. Can you find the thirteen triangles in it?
EVENTS
1638 Descartes, in a letter to Mersenne, proposed his folium (x3 + y3 = 2axy) as a test case to challenge Fermat’s differentiation techniques. To Descartes’ embarrassment, Fermat’s method worked better than his own. *VFR
1735 Abraham deMoivre elected to the Berlin Academy after Philipp Naud´e (1684–1747) presented a copy of deMoivre’s Miscellanea analytica of 1730. Among other things this book contains work on the Fibonacci sequence. See “Abraham deMoivre” by Helen M. Walker, Scripta Mathematica, 2(1933), 316–333. *VFR
In a historical note by Karl Pearson in 19241, evidence was presented which shows that Abraham De Moivre (1667–1754) invented the normal curve and the normal probability integral about 1721. The name of Gauss is usually attached to the normal curve, although it is not uncommon to find it more correctly attributed to Laplace. But as Pearson shows, De Moivre ante-dated both Laplace and Gauss in this by many years. “The matter is,” Pearson says, “a very singular one historically. De Moivre published in 1730 his Miscellanea AnalyticaMany copies of this work have attached to them a Supplementum with separate pagination, ending in a table of 14 figure logarithms of factorials from 10! to 900! by differences of 10. But only a very few copies have a second supplement, also with separate pagination (pp. 1–7) and dated Nov. 12, 1733.” The title of the second supplement is “Approximatio ad Summam Terminorum Binomii (a + b)n in Seriem expansi”, and it contains not only the first use of the normal curve, but also the first use of the approximation for large factorials commonly but improperly known as Stirling's. It is also clear that herein occurred the first correct use of the law of large numbers, usually attributed to Jacques Bernoulli (1654–1705) and often called Bernoulli's theorem. *W. EDWARDS DEMING in Nature, 04 November, 1933
1811 The aged Thomas Jefferson, confined to his room due to rheumatism, amuses him self with mathematical pursuits by calculating the lines for a sun-dial, as he reports in a letter to Charles Clay, "I have amused myself with calculating the hour lines of an horizontal dial for the latitude of this place, which I find to be 37o 22' 26". The calculations are for every five minutes of time, and are always exact to within less than half a second of a degree. " *John Fauval, From a lecture at the Univ of Va.
1993 Nintendo agreed to use Silicon Graphics Inc. technology in a video game player it was developing. The move came as SGI entered a struggle that would continue to sustain its business in designing machines and software for graphics-intensive computer work. Partnerships such as the one with Nintendo didn't stop SGI's decline as it struggled with decreasing revenues and leadership changes.
In 1966, the Lunar Orbiter 1 took the first photograph of the Earth from the Moon.*TIS
1977 Dr. Paul MacCready’s Gossamer Condor, powered only by the pilot, Bryan Allen, completed a 800-yard figure-8 flight to win the Kremer Prize. [Air & Space] *VFR
The MacCready Gossamer Condor was the first human-powered aircraft capable of controlled and sustained flight; as such, it won the Kremer prize in 1977. Its design was led by Paul MacCready of AeroVironment, Inc.
BIRTHS
1683 Giovanni Poleni ( 23 Aug, 1683;Venice,- 14 Nov, 1761; Padua) was an Italian mathematician who worked on hydraulics, physics, astronomy and archaeology *SAU He was the son of Marquess Jacopo Poleni and studied the classics, philosophy, theology, mathematics, and physics at the School of the Padri Somaschi, Venice. He was appointed, at the age of twenty-five, professor of astronomy at Padua. In 1715 he was assigned to the chair of physics, and in 1719 he succeeded Nicholas II Bernoulli as professor of mathematics. As an expert in hydraulic engineering he was charged by the Venetian Senate with the care of the waters of lower Lombardy and with the constructions necessary to prevent floods. He was also repeatedly called in to decide cases between sovereigns whose states were bordered by waterways.
Poleni was the first to build a calculator that used a pinwheel design. Made of wood, his calculating clock was built in 1709; he destroyed it after hearing that Antonius Braun had received 10,000 Guldens for dedicating a pinwheel machine of his own design to the emperor Charles VI of Vienna. Poleni described his machine in his Miscellanea in 1709, but it was also described by Jacob Leupold in his Theatrum Machinarum Generale ("The General Theory of Machines") which was published in 1727. In 1729, he also built a tractional device that enabled logarithmic functions to be drawn.
Poleni's observations on the impact of falling weights (similar to William 's Gravesande's) led to a controversy with Samuel Clarke and other Newtonians that became a part of the so-called "vis viva dispute" in the history of classical mechanics.
His knowledge of architecture caused Benedict XIV to call him to Rome in 1748 to examine the cupola of St. Peter's, which was rapidly disintegrating. He promptly indicated the repairs necessary. He also wrote a number of antiquarian dissertations. In 1710 he was elected a Fellow of the Royal Society, in 1739 the French Academy of Sciences made him a member and later the societies of Berlin and St. Petersburg did the same. The city of Padua elected him as magistrate, and after his death erected his statue by Canova. Venice also honoured him by striking a medal.
He married Orsola Roberti of Bassano della Grappa. *Wik
1778 Josef-Maria Hoëné de Wronski (23 August 1776 – 9 August 1853) wrote on the philosophy of mathematics. *SAU He wrote exclusively in French, desirous that his ideas, of whose immortality he was convinced, should be accessible to all; he worked, he said, "through France for Poland." He published over a hundred works, and left many more in manuscript. When dying in the seventy-fifth year of his life, he exclaimed: "God Almighty, there's still so much more I wanted to say!"
In science, Hoene-Wroński set himself maximal tasks: the complete reform of philosophy and of mathematics, astronomy, technology. He not only elaborated a system of philosophy, but applications to politics, history, economics, law, psychology, music, pedagogy. It was his aspiration to reform human knowledge in an "absolute, that is, ultimate" manner.
Though during his lifetime nearly all his work was dismissed as nonsense, some of it has come in later years to be seen in a more favorable light. Although nearly all his grandiose claims were in fact unfounded, his mathematical work contains flashes of deep insight and many important intermediary results. Most significant was his work on series. He had strongly criticized Lagrange's use of infinite series, introducing instead a novel series expansion for a function. His criticisms of Lagrange were for the most part unfounded, but the coefficients in Wroński's new series were found to be important after his death, forming the determinants now known as the Wronskians (the name was given them by Thomas Muir in 1882).
The level of Wroński's scientific and scholarly accomplishments, and the amplitude of his objectives, placed Wroński in the first rank of European metaphysicians in the early 19th century. But the abstractness, formalism and obscurity of his thought, the difficulty of his language, his boundless self-assurance, his uncompromising judgments of others—alienated. He was perhaps the most original of the Polish metaphysicians, but others were more representative of the Polish outlook. *Wik
1797 Adhémar Jean Claude Barré de Saint-Venant (August 23, 1797, Villiers-en-Bière, Seine-et-Marne – January 1886, Saint-Ouen, Loir-et-Cher) was a mechanician and mathematician who contributed to early stress analysis and also developed the one-dimensional unsteady open channel flow shallow water equations or Saint-Venant equations that are a fundamental set of equations used in modern hydraulic engineering. Although his surname was Barré de Saint-Venant in non-French mathematical literature he is known simply as Saint-Venant. His name is also associated with Saint-Venant's principle of statically equivalent systems of load, Saint-Venant's theorem and for Saint-Venant's compatibility condition, the integrability conditions for a symmetric tensor field to be a strain.
In 1843 he published the correct derivation of the Navier-Stokes equations for a viscous flow and was the first to "properly identify the coefficient of viscosity and its role as a multiplying factor for the velocity gradients in the flow". Although he published before Stokes the equations do not bear his name.
Barré de Saint-Venant developed a version of vector calculus similar to that of Grassmann (now understood as exterior differential forms) which he published in 1845. A dispute arose between Saint-Venant and Grassmann over priority for this invention. Grassmann had published his results in 1844, but Barré de Saint-Venant claimed he had developed the method in 1832. *Wik
1811 Auguste Bravais (23 Aug 1811; 30 Mar 1863) French physicist and mineralogist, best remembered for his work on the lattice theory of crystals. Bravais lattices are named for him. In 1850, he showed that crystals could be divided into 14 unit cells for which: (a) the unit cell is the simplest repeating unit in the crystal; (b) opposite faces of a unit cell are parallel; and (c) the edge of the unit cell connects equivalent points. These unit cells fall into seven geometrical categories, which differ in their relative edge lengths and internal angles. In 1866, he elaborated the relationships between the ideal lattice and the material crystal. Sixty years later, Bravais' work provided the mathematical and conceptual basis for the determination of crystal structures after Laue's discovery of X-ray diffraction in 1911. *TIS Auguste Bravais is best known for pointing out that there are in total 14 types of crystallographic lattices. His ordering and denomination of lattices is still in use today. *Arjen Dijksman, commonsensequantum.blogspot.fr
1817 Sarah Frances Whiting (August 23, 1847 – September 12, 1927), American physicist and astronomer, was the instructor to several astronomers, including Annie Jump Cannon.
Whiting graduated from Ingham University in 1865.
She was appointed by Wellesley College president Henry Fowle Durant, one year after the College's 1875 opening, as its first professor of physics. She established its physics department and the undergraduate experimental physics lab at Wellesley, the second of its kind to be started in the country. At the request of Durant, she attended lectures at MIT given by Edward Charles Pickering. He invited Whiting to observe some of the new techniques being applied to astronomy, such as spectroscopy. In 1880, Whiting started teaching a course on Practical Astronomy at Wellesley.
In 1895, as told by biographer Annie Jump Cannon,
An especially exciting moment came when the Boston morning papers reported the discovery of the Rontgen or X-rays in 1895. The advanced students in physics of those days will always remember the zeal with which Miss Whiting immediately set up an old Crookes tube and the delight when she actually obtained some of the very first photographs taken in this country of coins within a purse and bones within the flesh.
Between 1896 and 1900, Whiting helped Wellesley College trustee Sarah Elizabeth Whitin to establish the Whitin Observatory, of which Whiting became the first director.
Tufts College bestowed an honorary doctorate on Whiting in 1905. She was also known for supporting prohibition.
Whiting retired from Wellesley in 1916 and was a Professor Emeritus until her death in 1927. She is buried in Machpelah Cemetery in Le Roy, New York, near her now-defunct alma mater.*Wik
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| Whitin Observatory |
1829 Birthdate of Moritz Cantor, (23 Aug 1829;10 Apr 1920)
German historian of mathematics, one of the greatest of the 19th century. He is best remembered for the four volume work Vorlesungen über Geschichte der Mathematik which traces the history of mathematics up to 1799. The first volume (published 1880) traces the general history of mathematics up to 1200. The second volume traces the history up to 1668 (the year Newton and Leibniz were just about to embark on their mathematicalresearches). The third volume continues up to 1758 (Lagrange's work began shortly after this date). Cantor then, at the age of 69, as editor-in-chief, organised a team with nine further contributors to collaborate on the fourth volume (published 1908), continuing to 1799, the year of Gauss's doctoral thesis. *TIS
1842 Osborne Reynolds (23 Aug 1842 in Belfast, Ireland - 21 Feb 1912 in Watchet, Somerset, England) was an Irish mathematician best known for introducing the Reynolds number classifying fluid flow.*SAU British innovator in the understanding of fluid dynamics. Separately, his studies of heat transfer between solids and fluids brought improvements in boiler and condenser design. He spent his entire career at what is now the University of Manchester. *Wik
1875 William Henry Eccles (23 Aug 1875; 29 Apr 1966); British physicist who pioneered in the development of radio communication. Eccles was an early proponent of Oliver Heaviside's theory that an upper layer of the atmosphere reflects radio waves, thus enabling their transmission over long distances. He also suggested in 1912 that solar radiation accounted for the differences in wave propagation during the day and night. He experimented with detectors and amplifiers for radio reception, coined the term "diode," and studied atmospheric disturbances of radio reception. After WW I, he made many contributions to electronic circuit development*, including the Eccles-Jordan "flip-flop" patented in 1918 and used in binary counters (working with F.W. Jordan).*TIS
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1893 Joseph Fels Ritt (August 23, 1893–January 5, 1951) was an American mathematician at Columbia University in the early 20th century.
He is known for his work on characterizing the indefinite integrals that can be solved in closed form, for his work on the theory of ordinary differential equations and partial differential equations, for beginning the study of differential algebraic groups, and for the method of characteristic sets used in the solution of systems of polynomial equations.*Wik
1909 Florence Nightingale David, also known as F. N. David (August 23, 1909 - July 23, 1993) was an English statistician, born in Ivington, Herefordshire, England. She was named after Florence Nightingale, who was a friend of her parents.
David read mathematics at Bedford College for Women in London. After graduation, she worked for the eminent statistician Karl Pearson at University College, London as his research student. She calculated the distribution of correlation coefficients, producing in 1938 her first book, Tables of the correlation coefficient.
After Karl Pearson died in 1934, she returned to the Biometrics laboratory to work with Jerzy Neyman where she submitted her last four published papers as her PhD thesis. During World War II, David worked for the Ministry of Home Security. In late 1939 when war had started but England had not yet been attacked, she created statistical models to predict the possible consequences of bombs exploding in high density populations such as the big cities of England and especially London. From these models, she determined estimates of harm to humans and damage to non-humans This included the possible numbers living and dead, the reactions to fires and damaged buildings as well as damages to communications,utilities such as phones, water, gas, electricity and sewers. As a result when the Germans bombed London in 1940 and 1941, vital services were kept going and her models were updated and modified with the evidence from the real harms and real damage.
David became head of the Statistics Department at the University of California at Riverside in 1970.*Wik
1919 Dirk Polder (August 23, 1919, The Hague — March 18, 2001, Iran) was a Dutch physicist who, together with Hendrik Casimir, first predicted the existence of what today is known as the Casimir-Polder force, sometimes also referred to as the Casimir effect or Casimir force. He also worked on the similar topic of radiative heat transfer at nanoscale.
In quantum field theory, the Casimir effect (or Casimir force) is a physical force acting on the macroscopic boundaries of a confined space which arises from the quantum fluctuations of a field. It is named after the Dutch physicist Hendrik Casimir, who predicted the effect for electromagnetic systems in 1948.
In the same year, Casimir together with Dirk Polder described a similar effect experienced by a neutral atom in the vicinity of a macroscopic interface, which is called the Casimir–Polder force. Their result is a generalization of the London–van der Waals force and includes retardation due to the finite speed of light. The fundamental principles leading to the London–van der Waals force, the Casimir force, and the Casimir–Polder force can be formulated on the same footing.*Wik
1923 Edgar Frank "Ted" Codd (19 August 1923 – 18 April 2003). His main achievement besides many contributions to computer science was the invention of the relational model for database management, the theoretical basis for relational databases.
“At the time, Nixon was normalizing relations with China. I figured that if he could normalize relations, then so could I.”
When you talk about databases today, usually you are referring to relational databases that store their data within tables, interconnected via so-called keys. Of course there are also modern alternatives such as e.g. graph based databases, but relational databases are widespread and rather common today. And this is also thanks to E.F. Codd and his relational algebra.
*/scihi.org/
1928 Israel Gohberg ( 23 August 1928 – 12 October 2009) was a Bessarabian-born Soviet and Israeli mathematician, most known for his work in operator theory and functional analysis, in particular linear operators and integral equations.
He studied at the Kyrgyz Pedagogical Institute in Bishkek and at Moldova State University in Chișinău, completed his doctorate at Leningrad State University on a thesis advised by Mark Krein (1954), and attended Moscow State University for his habilitation degree.
Gohberg joined the faculty at the Teacher's college in Soroca and the Teachers college in Bălți before returning to Chișinău where he was elected into the Academy of Sciences and also being appointed head of functional analysis at Moldova State University (1964–73). After moving to Israel, he joined Tel Aviv University (1974) and was at the Weizmann Institute at Rehovot. Since then he also had positions at Vrije Universiteit in Amsterdam (1983), as well as at the University of Calgary and the University of Maryland, College Park.
He founded the Integral equations and operator theory journal (1983).
Gohberg was the visionary and driving force of the International Workshop on Operator Theory and its Applications, or IWOTA, starting with its first meeting on August 1, 1981. He became a lifetime president of the IWOTA Steering Committee and a founder of the Springer / Birkhäuser Verlag book series Operator Theory: Advances and Applications (OTAA).
Gohberg was awarded the Humboldt Prize in 1992. He received honorary doctorates from the Darmstadt University of Technology in 1997; from the Vienna University of Technology in 2001; from West University of Timișoara in 2002; from Moldova State University, Chișinău, Moldova in 2002; from Alecu Russo State University, Bălți, Moldova in 2002; and from Technion, June 2008. He also was awarded the M.G. Krein Prize of the Ukrainian Academy of Sciences in 2008, and was elected SIAM Fellow in 2009.
He died in Ra'anana in 2009.
1929 Anthony James Merrill Spencer (23 August 1929 — 26 January 2008) FRS was an applied mathematician whose main field of research was in understanding and predicting the mechanical behavior of advanced materials.*Wik
Anthony J. M. Spencer, known to all as Tony, was one of the most outstanding British applied mathematicians of his generation. His main field of research was in understanding and predicting the mechanical behaviour of advanced materials. His insight and skill in formulating constitutive equations enabled him to develop new models of materials and then solve physically significant problems in the fields of composites, granular materials and laminates. He studied at Cambridge, Birmingham and Keele and, after postdoctoral research in the acclaimed Division of Applied Mathematics at Brown University in the USA and a short period of employment in government service, moved to Nottingham University and spent the rest of his career there. He soon became Head of the Department of Theoretical Mechanics, which had been formed in 1960 and given responsibility for teaching mathematics to students in the Faculty of Applied Science. Under Tony's guidance and inspirational leadership it gained an unrivalled reputation, by virtue of its productivity in research, the quality of its staff and its innovative approach to undergraduate teaching and graduate training. Although firmly rooted in Nottingham, Tony travelled widely and was very well known. He was an astute and highly proficient research worker whose views were prized by his many collaborators and friends in the solid mechanics community. It is a measure of his intellectual strength and dedication that he published 40 research papers in his 13 years of retirement. *Royal Society Pub
1933 Robert Floyd Curl Jr. (August 23, 1933 – July 3, 2022) American chemist who with Richard E. Smalley and Sir Harold W. Kroto discovered the first fullerene, a spherical cluster of carbon atoms, in 1985. The discovery opened a new branch of chemistry, and all three men were awarded the 1996 Nobel Prize for Chemistry for their work. In Sep 1985 Curl met with Kroto of the University of Sussex, Eng., and Smalley, a colleague at Rice, and, in 11 days of research, they discovered fullerenes. They announced their findings to the public in the 14 Nov 1985, issue of the journal Nature.*TIS
Born in Alice, Texas, United States, Curl was the son of a Methodist minister. Due to his father's missionary work, his family moved several times within southern and southwestern Texas, and the elder Curl was involved in starting the San Antonio Medical Center's Methodist Hospital.[Curl attributes his interest in chemistry to a chemistry set he received as a nine-year-old, recalling that he ruined the finish on his mother's porcelain stove when nitric acid boiled over onto it.
DEATHS
1806 Charles-Augustin de Coulomb (14 June 1736, 23 Aug 1806) French physicist best known for the formulation of Coulomb's law, which states that the force between two electrical charges is proportional to the product of the charges and inversely proportional to the square of the distance between them. Coulombic force is one of the principal forces involved in atomic reactions.*TIS
1923 Phoebe Sarah Hertha Ayrton (28 April 1854 – 23 August 1923), was a British engineer, mathematician, physicist, and inventor. Known in adult life as Hertha Ayrton, born Phoebe Sarah Marks, she was awarded the Hughes Medal by the Royal Society for her work on electric arcs and ripples in sand and water.
In 1880, Ayrton passed the Mathematical Tripos, but Cambridge did not grant her an academic degree because, at the time, Cambridge gave only certificates and not full degrees to women. Ayrton passed an external examination at the University of London, which awarded her a Bachelor of Science degree in 1881.
In 1899, she was the first woman ever to read her own paper before the Institution of Electrical Engineers (IEE). Her paper was entitled "The Hissing of the Electric Arc". Shortly thereafter, Ayrton was elected the first female member of the IEE; the next woman to be admitted to the IEE was in 1958. She petitioned to present a paper before the Royal Society but was not allowed because of her sex and "The Mechanism of the Electric Arc" was read by John Perry in her stead in 1901. Ayrton was also the first woman to win a prize from the Society, the Hughes Medal, awarded to her in 1906 in honour of her research on the motion of ripples in sand and water and her work on the electric arc. By the late nineteenth century, Ayrton's work in the field of electrical engineering was recognised more widely, domestically and internationally. At the International Congress of Women held in London in 1899, she presided over the physical science section. Ayrton also spoke at the International Electrical Congress in Paris in 1900. Her success there led the British Association for the Advancement of Science to allow women to serve on general and sectional committees. *Wik
1973 Helmuth Kneser (April 16, 1898 – August 23, 1973) published on sums of squares in fields, on groups, on non-Euclidean geometry, on Harald Bohr's almost periodic functions, on iteration of analytic functions, on the differential geometry of manifolds, on local uniformisation and boundary values. He succeeded in pushing forward Weierstrass and Hadamard's ideas to open up the area of the value distribution of meromorphic functions. Kneser, writing of his work on this last topic said:"I hope that this theory will also prove fruitful for the special functions used in analysis, this has to be required of a new theory, in particular, if one considers that the general theory of rational functions of one indeterminate came from the treatment of special functions, namely the gamma and sigma functions by Weierstrass and of the Riemann zeta function by Hadamard. " *SAU
1988 Hans Lewy (October 20, 1904 – August 23, 1988) was an American mathematician, known for his work on partial differential equations and on the theory of functions of several complex variables. *Wik
1907 Gordon Stanley Brown (August 30, 1907 in Australia – August 23, 1996 in Tucson, Arizona) was a professor of electrical engineering at MIT. He originated many of the concepts behind automatic-feedback control systems and the numerical control of machine tools] From 1959 to 1968, he served as the dean of MIT's engineering school. With his former student Donald P. Campbell, he wrote Principles of Servomechanisms in 1948, which is still a standard reference in the field.
2001 Fred Hoyle (24 Jun 1915, 23 Aug 2001) English astronomer who coined the term "Big Bang." He became Britain's best-known astronomer in 1950 with his broadcast lectures on the nature of the universe. He recalled using "big bang" for the first time in the last of those talks, though he never accepted that theory for the origin of the universe. Working with Hermann Bondi and Thomas Gold, Hoyle had proposed the steady state theory in the 1940s, arguing that the universe developed in a process of continuous growth. Over time, his belief in a "steady state" universe was shared by fewer and fewer scientists because of new discoveries. Hoyle also did theoretical work on the formation - in older, hotter stars - of other elements as helium nuclei fuse to produce carbon, oxygen, and eventually elements up to iron. *TIS
I am told he is also the author of Robin Whitty's (Theorem of the Day) favorite sci-fi novel, The Black Cloud
Hoyle is often confused with the origin of "According to Hoyle" explained in my post, Done Right.
2016 Reinhard Justus Reginald Selten (5 October 1930 – 23 August 2016) was a German economist, who won the 1994 Nobel Memorial Prize in Economic Sciences (shared with John Harsanyi and John Nash). He is also well known for his work in bounded rationality and can be considered one of the founding fathers of experimental economics.
He was a visiting professor at Berkeley and taught from 1969 to 1972 at the Free University of Berlin and, from 1972 to 1984, at the University of Bielefeld. He then accepted a professorship at the University of Bonn. There he built the BonnEconLab, a laboratory for experimental economic research, where he was active even after his retirement.
Selten was professor emeritus at the University of Bonn, Germany, and held several honorary doctoral degrees. He had been an Esperantist since 1959 and met his wife through the Esperanto movement. He was a member and co-founder of the International Academy of Sciences San Marino.
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
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