PEIRCE, BENJAMIN. LL.D., 1809-80, b. Mass.; graduated at Harvard in 1829; tutor there in 1831; university professor of physics and mathematics 1833; and Perkens pro fessor of astronomy and mathematics 1842, which position lie held till his death; in 1849 consulting astronomer to the American Ephemeris and ilrautical Almanac; and in 1855 one of the council to organize the Dudley observatory, Albany. In 1867 lie succeeded prof. A. D. Bache as supt. of coast survey, in which service he continued till 1874. In his early life lie was a contributor to the Mathematical Miscellany, and also published the Cambridge ili.seellany of Mathematics, Physics, and Astronomy, in which appeared his celebrated investigation of the motion of a top spinning on a plane surface. He also prepared a series of mathematical text books for the use of the university, and it was chiefly by his exertions that the Harvard observatory was established and perfected. In the first volume of the Proceedings of the American _Academy (f Arts and Sciences, lie published a paper on the discovery of Neptune, in which lie demonstrated that the mass, the distance from the sun, arch the conditions of the planet itself differed from the conclusions of and Adams, and that the discovery of Neptune by Calle nearly in the place indicated by Leverrier, although that astronomer's calculations were pro found, was due to accident. This paper was followed by another, discussing the relations of Neptune to Uranus. In 1851 he published in the Astronomical .Journal remarkable papers on the constitution of Saturn's rings, in which lie considered the con ditions of statical equilibrium of a transverse section of a ring, and came to the con clusion that if there are separate rings, they must be more numerous than Laplace had even supposed. From these deduetions others have followed by other mathematicians,
particularly prof. J. Clerk Maxwell, which have resulted in considerable changes of view in regard to the Saturnian system. See SATURN. lu 1857 be gave sonic of the most brilliant results in analytical mechanics, in a volume which also contained many original demonstrations. Prof. Peirce made other important contributions to mathematics and physics, which will for a long time form the basis of future investigations by others. Among these may be mentioned his researches upon the personal equation, and his investigation of the forms of an elastic sac containing a fluid, a subject which led to the theory of analytic morphology. His contributions to algebra are of the broadest and pro foundest character. They are principally embraced in certain communications on linear associative algebra, to the national academy of sciences, which had beets sug gested by the publication by Hamilton in 1852, of his " quaternions." These com munications were collected in 1870, and 100 lithograph copies, were published. This book is a marvel of profundity and mathematical genius. Prof. Peirce was made an associate of the royal astronomical society of London in 1849, and of the royal society of London in 1832: He was one of the original members of the national academy of sciences, and was a member of various learned societies in Europe and America.