# The New Student's Reference Work/Poisson, Simeon Denis

**Poisson** (*pwä′ sôn′*), **Simeon Denis,** an eminent French mathematical physicist, was born at Pithiviers, June 21, 1781, and died at Paris, April 25, 1840. He was educated at the *École Centrale* at Fontainebleau and at the *École Polytechnique* at Paris. Only four years after entering the latter he became its professor of mechanics and analysis. In 1812 he was elected to the Academy. Among his most important works must be mentioned, in pure mathematics, his contributions to the calculus of variations and to the theory of probabilities; in astronomy, his proof of the stability of the solar system; in physics, his very important theorems in electrostatics and in fluid motion, his theory of capillarity and his mathematical theory of heat. His *Mechanics* was a standard textbook for half a century. See Arago’s *Notices Biographiques,* Vol. 2.