Clairault, Alexis Claude

, a celebrated French mathematician and academician, was born at Paris, May 13, 1713, and died May 17, 1765. His father, a teacher of the mathematics at Paris, who was his sole instructor, taught him even the letters of the alphabet on the figures of Euclid’s Elements, by which he was able to read and write at four years of age, and by a similar stratagem calculations were rendered familiar to him. At nine years of age he put into his hands Guisnee’s “Application of Algebra to Geometry” at ten he studied l'Hopital’s “Conic Sections;” and between twelve and thirteen, he read a memoir to the academy of sciences, concerning four new geometrical curves of his own invention. About the same time he laid the first foundation of his work upon curves that have a double curvature, which he finished in 1729, at sixteen years of age. He was named adjoint-mechanician to the academy in 1731, at the age of eighteen, associate in 1733, and pensioner in 1738. During his connection with the academy, he sent a great multitude of learned and ingenious communications to their Memoirs, from 1727, almost every year, to 1762, and wrote several other works, which he published separately, as, 1. “On Curves of a Double Curvature,” in 1730, 4to. 2. “Elements of Geometry,” 1741, 8vo. 3. “Theory of the Figure of the Earth,” 1743, 8vo. 4. “Elements of Algebra,” 1746, 8vo. 5. “Tables of the Moon,” 1754, 8vo. ²