CLAIRAUT, ALEXIS CLAUDE (1713 65). A prominent French mathematician, physicist, and astronomer, horn in Paris. He showed a precocity analogous to that of Pascal. At the age of ten he read 111CipitaFs works on infinitesimal analysis and comic sections; be fore lie was thirteen he presented a memoir on curves to the French Academy of Sciences; at sixteen he published his first work. on curves of double curvature, and at eighteen he was elected a member of the Aeademy. In 1736 he was appointed to accompany 1:\faupertuis on an expedition to Lapland, for the purpose of meas uring a degree of the meridian—a work which proved, contrary to the opinion of Cassini, the flattening of the I-3 t II toward the noles. Shortly after his return, in 17-1:3, appeared his Th,:orie de la figure de la tern-. based on Newton's law of gravitation, and on Maclaurin's results con cerning homogeneous ellipsoids. in the field of mathematics Cla iraut studied curves of the third order, tortuous curves and projections, and was the first to find the singular solution of a dif ferential equation of the first degree in in and q. The equation used by Clairant. often called Clairaut's form, is y = f (p), in which p d In physics lie first showed the sity of considering the attraction between the parts of the fluid itself, in order to explain the phenomenon of eapillary action; computed the change in gravity at high latitudes. and so fully
demonstrated the figure of the that little essentially new has since been added. At least. according to Todh on ter. "The splendid analysis which Laplace supplied, adorned but did not really alter the theory which started from the creative hands of Clairaut." In the tield of astronomy he solved the famous problem of three bodies in the case of the sun, earth, and moon; explained the motion of •the lunar up sides, and constructed lunar tables, later sup planted by those of Mayer. Clairaut also pre dicted the return of Halley's comet for about April 15, 1759; although the degree of accuracy was remarkable for the time, and the approxima tion closer than Halley's, it failed by a month, and subjected its author to the ridicule of his rival, D'Alembert. During his last years fond TICS!: for society and desire for luxury hindered his scientific work. His leading works (pub lished in Paris) are: Recherches snr lee cou•bes d double courbuie (1731) ; Truitt' de in figure de la term (1743 and 1808): The'orie de In lime (1752 and 1765) ; El•'ments de yjonie'trie (1741 and 1765) : Ehccnents d'aigare (1746 and 1760) ; and Theorie du moueenient des (-metes (1760).