FOURIER, JEAN BAPTISTE JOSEPH, Baron, a distinguished French mathematician, was b. of a respectable family at Auxerre, 21st Mar., 1768. He became a pupil, end at the age of 18, a professor, in the military school of his native place. He was after wards removed to the normal school in Paris, and then to the Polytechnic, and accom• panted gen. Bonaparte to Egypt. Besides performing political services on this occasion, he was secretary to the Institut d'Egypte, and an active contributor to the Description de r Egypte, the masterly historical introduction to which is from his pen. On returning to France, he was made prefet of the department of Isere in 1802, an office which he held till 1815, and was created baron in 1808. As prefet, he succeeded in draining the marshes in Bourgoin, near Lyons, which had for centuries baffled all attempts. On the return of Napoleon from Elba, F. issued a royalist proclamation; notwithstanding which he was appointed by Napoleon prefet of the department of the Rhone, but was sliortly after removed. He now took up his abode in Paris, and devoted himself exclusively to
science. The academy of sciences, which in 1807 had crowned his essay on the propa gation of heat through solid bodies,' chose him a member in 1815, and afterwards secretary for life, conjointly with envier. He died 16th May, 1830.
His most famous work is the Theorie Analytique de la. Cliakur (Par. 1822), in which he applies new methods of mathematical investigation. An allied subject is discussed in his Memoire sur les Temperatures du Globe Terrestre et des Espaces Planetaires (Par. 1827). Besides heat, he occupied himself with the theory of equations, which received from him important improvements. His work, Analyse des Equations Piterminees, distin guished both for its substance and manner of exposition, was left unfinished, and was published after his death by Navier (Par. 1831).