The New International Encyclopædia/Fourier, Jean-Baptiste Joseph, Baron

FOURIER,, Baron (1768-1830). A French geometer and physicist, born at Auxerre. He was the son of a poor tailor, and was left an orphan at the age of eight. The Bishop of Auxerre, recognizing his ability, placed him in a Church military school, where he soon showed a decided aptitude for mathematics. At the age of nineteen he wrote his memoir, Sur la résolution des équations numériques de degré quelconque, which was presented to the Academy in 1789. He took part in the Revolution, but in 1795 was sent as a student to the newly founded Ecole Normale, and soon after obtained the chair of analysis in the Ecole Polytechnique (1795-98). He went to Egypt in 1798 and was made perpetual secretary of the Institute of Cairo, and in the following year was placed at the head of one of the two scientific expeditions to the upper Nile. He returned to France in 1801 and was made (1802) Prefect of Isère, a position which he filled with his usual tact and energy. Napoleon created him a baron in 1808; but as, in 1814, he gave brief allegiance to the Bourbons, his political career was wrecked by the return of the Emperor from Elba. He was, after much difficulty, made a member of the Academy of Sciences in 1815, and succeeded Delambre (1822) as perpetual secretary for the mathematical sciences. He later became a member of the French Academy (1826). Fourier was one of the leading mathematical physicists of his time. His labors were divided between the study of the theory of

heat and of numerical equations. Among his leading works are the following: Théorie analytique de la chaleur (1822); Analyse des équations déterminées (posthumous, 1831); a memoir on statics (Journal de l'Ecole Polytechnique, 1797-98); and numerous memoirs on equations. His works, including references to numerous biographical sketches, were published by Darboux under the title, Œuvres de Fourier (Paris, 1889-90).

Fourier's Series, communicated by Fourier to the Academy toward the end of 1807, plays an important part in mathematical physics. Consult Du Bois-Reymond, Zur Geschichte der trigonometrischen Reihen (Tübingen, 1880).