Alexis Claude Clairaut http://www.sciencedaily.com/encyclopedia/alexis_claude_clairaut

A.C. Clairaut was a leading French mathimatician of his time. He was very well known as both a mathimatician and a physicist. By the time he was 10 years old, he had already influenced the calculus world with the make up of his own differential equation:

Y = Dxy + f(Dxy) => y = cx + f(c)

At the age of twelve, he had begun working on curves and space, which had gained him acceptance into the Academy of Science in Paris. The academy allowed him the time to grow and further his studies of geometry. At the age of eighteen, Clairaut published his first work that consisted of all types of additions to the world of geometry. He gave a demonstration on one of Newton’s fact that all curves of the third order were projections of 1 of 5 parabolas. These geometric additions won him membership into the Academy of Science in 1731.

Clairaut was one of the participating scientist who helped obtain and measure the meridian degree of the earth’s surface. This exhibition allowed him to publish his "Theory on the Shape of the Earth" which dealt with the equilibrium and attractions of ellipsoids of revolution in 1743. In 1752, Clairaut published his "Theory of the Moon" which is considered by many to be completely Newton in character.

Alexis Claude Clairaut (May 13 1713 - May 17 1765) was a French mathematician. He was a prodigy - at the age of twelve he wrote a memoir on four geometrical curves; his first important work was a treatise on tortuous curves, published when he was eighteen - a work which procured for him admission to the French Academy. He was born and died in Paris. In 1731 he gave a demonstration of the fact noted by Newton that all curves of the third order were projections of one of five parabolas. In 1741 Clairaut went on a scientific expedition to measure the length of a meridian degree on the earth's surface, and on his return in 1743 he published his Théorie de la figure de la terre. This is founded on a paper by Maclaurin, which had shown that a mass of homogeneous fluid set in rotation about a line through its centre of mass would, under the mutual attraction of its particles, take the form of a spheroid. This work of Clairaut treated of heterogeneous spheroids and contains the proof of his formula for the accelerating effect of gravity in a place of latitude l. In 1849 Stokes shewed that the same result was true whatever was the interior constitution or density of the earth, provide the surface was a spheroid of equilibrium of small ellipticity. Impressed by the power of geometry as shewn in the writings of Newton and Maclaurin, Clairaut abandoned analysis, and his next work, the Théorie de la lune, published in 1752, is strictly Newtonian in character. This contains the explanation of the motion of the apsis which had previously puzzled astronomers, and which Clairaut had at first deemed so inexplicable that he was on the point of publishing a new hypothesis as to the law of attraction when it occurred to him to carry the approximation to the third order, and he thereupon found that the result was in accordance with the observations. This was followed in 1754 by some lunar tables. Clairaut subsequently wrote various papers on the orbit of the moon, and on the motion of comets as affected by the perturbation of the planets, particularly on the path of Halley's comet. His growing popularity in society hindered his scientific work: engagé, says Bossut, à des soupers, à des veilles, entraîné par un goût vif pour les femmes, voulant allier le plaisir à ses travaux ordinaires, il perdit le repos, la santé, enfin la vie à l'âge de cinquante-deux ans. See also: Clairaut's equation This page is based on public domain text taken from 'A Short Account of the History of Mathematics' (4th edition, 1908) by W. W. Rouse Ball.