Poisson
SIMÉON-DENIS, a French geometer; born in Pithiviers, department of Loiret, June 21, 1781; and displaying an aptitude for mathematics, he was received into the Ecole Polytechnique in 1798. In 1802 he became a professor in the Polytechnique; in 1808 a member of the Bureau des Longitudes; in 1809 professor in the Faculty of Sciences; member of the Institute in 1812, etc.; and this list of distinctions was crowned in 1837 by his elevation to the dignity of a peer of France. Poisson's whole life was devoted to the prosecution of scientific research, and the fruits of his pen number about 300 memoirs. Of the separate treatises published by Poisson, the best known is the "Treatise on Me chanics" (1833); others were on capillary action, the mathematical theory of heat, the motion of projectiles, and, lastly, the celebrated work "On the Invaria bility of the Mean Movement of the Planetary Axes." Poisson is fairly considered one of the chief founders of the science of mathematical physics. He died April 25, 1840.