LAPLACE, PIERRE SIMON, Marquis (le, one of the greatest of mathematicians and astroziorners, was b. Mar. 23, 1749, at Beaumont-en-Auge, in the department of Calva dos; was for some time a teacher of mathematics in the military school there, and afterwards went to Parisi where,. having attracted the notice. of .1‘)'Alenabert, he was, through his influence, appointed professor in the military school, and was admitted a member of the academy of sciences. Ile had by this time mastered the whole of mathematical science as then known, and had besides solved several problems had for many years defied the attempts of geometers; and now it occurred to him to devote his mathematical powers to the service of astronomy, and he accordingly com menced to plan the work which afterwards appeared as the Mecanique Celeste. In his political life, Laplace presents a sorry picture. He was appointed minister of the inte rior by Bonaparte, but was, after six weeks, deposed for incapacity. He continued, however, to receive marks of honor from Napoleon, and on the erection of the imperial throne was made a count. In 1814 he voted for the appointment of the provisional government, for Napoleon's deposition, and the restoration of the Bourbons. After the second restoration, Louis XV111. made him a peer and a marquis. In the chamber of peers he showed, as he had done under the revolutionary government, the greathst unfit ness for political affairs, and the most extreme servility. He died at Paris, Mar. 5,
1827. Laplace was gifted with wonderful scientific sagacity; this appears especially in his explanations certain results of mathematical analysis formerly looked upon as inexplicable, but which he showed to be the expression of physical phenomena which had hitherto escaped detection, and subsequent observations generally confirmed Laplace's conclusions. Above all his powers, his wonderful memory shone pre-emi nent. His Alecanique Celeste, and supplements to it (5 vols., Paris, 1709-1825), are, next to Newton's Principia, the greatest of astronomical works. Ilis Exposition de,Systilne du Monde (2 vols., Paris, 1796; 6th ed. 1824) is intended for thoSe who cannot follow the difficult demonstrations and calculations in his great work. All Laplace's important investigations were made for the purpose of testing the generality of the law of gravi tation, and the cause of sundry irregularities in the motions of the planets. His works comprise many able treatises on particular subjects in astronomy, pure mathematics, probabilities, mechanics, heat, and electricity; most of then' being memoirs communi cated to the academy of sciences.