DELAUNAY, CHARLES-EUGNE

born April 9, 1816, Lusigny-sur-Barse, Fr. died Aug. 5, 1872, near Cherbourg French mathematician and astronomer whose theory of lunar motion advanced the development of planetary-motion theories. Delaunay was educated as an engineer at the cole des Mines from 1836, becoming an engineer in 1843 and chief engineer in 1858. He studied mathematics and astronomy with Jean-Baptiste Biot at the Sorbonne (184148). He taught mechanics at the cole Polytechnique from 1850 and also later taught at the cole des Mines. He was made a member of the Acadmie des Sciences in 1855; and in 1870 he succeeded U.-J.-J. Le Verrier as director of the Paris Observatory. He wrote Cours lmentaire de mcanique (1850; 8th ed., 1874; Elementary Course of Mechanics), Cours lmentaire d'astronomie (1853; 5th ed., 1870; Elementary Course of Astronomy), La Thorie du mouvement de la lune, 2 vol. (186067; The Theory of Lunar Motion), Trait de mcanique rationnelle (1856; 4th ed., 1873; Treatise of Theoretical Mechanics), Ralentissement de la rotation de la terre (1866; Slowing of the Rotation of the Earth), and Rapport sur les progrs de l'astronomie (1867; Report on the Progress of Astronomy).