The French mathematical physicist Jean Baptiste Joseph, Baron Fourier (1768-1830), was the first to discuss in a comprehensive manner the various aspects of the flow of heat in bodies.

# Baron Jean Baptiste Joseph Fourier

On March 21, 1768, J.B.J. Fourier was born in Auxerre. At the age of 8 he lost his father, but the bishop of Auxerre secured his admission to the local military school conducted by Benedictine monks. After 2 years (1787-1789) in the novitiate of the Benedictine abbey of Saint-Benoît-sur-Loire, he left to serve as a lay teacher in his former school at Auxerre.

In 1789 Fourier's first memoir on the numerical solution of algebraic equations was read before the French Academy of Sciences. In 1794 a central teachers' college (École Normale) was established in Paris, and Fourier was one of its first students, but before long he was promoted to the faculty as lecturer. He then received an appointment to the newly founded École Polytechnique, where he first served as chief lecturer on fortifications and later as professor of mathematical analysis.

Fourier was 30 when Napoleon requested his participation as scientific adviser on an expedition to Egypt. Fourier served from 1798 to 1802 as secretary of the Institut d'Égypte, established by Napoleon to explore systematically the archeological riches of that ancient land. His papers, published in the *Décade* and the *Courrier d'Égypte,* showed him to be preoccupied with problems that ranged from the general solution of algebraic equations to irrigation projects.

Fourier proved himself a tactful diplomat, and upon his return to France Napoleon appointed him perfect of the department of lsère, with Grenoble as its capital, where he served from 1801 to 1814. There he wrote the work on the mathematical theory of heat conduction which earned him lasting fame. Its first draft was submitted to the academy in 1807; a second, much expanded version, which received the award of the academy in 1812, was *entitled Théorie des mouvements de la chaleur dans les corps solides.* The first part of it was printed in book form in 1822 under the title *Théorie analytique de la chaleur.* It was a masterpiece, not only because it covered the hitherto unexplored field of heat propagation but also because it contained the mathematical techniques which later were developed into a special branch of mathematics—Fourier analysis and Fourier integrals.

From 1815 Fourier served as director of the Bureau of Statistics in Paris. In the eyes of the new, royalist regime, Fourier's long service under Napoleon was offset by his opposition to Napoleon upon the latter's return from Elba. In 1817 he became a member of the Academy of Sciences and served from 1822 as its perpetual secretary.

During the course of his career Fourier wrote several papers on statistics, but his lifelong love was the theory of algebraic equations on which he had just completed the manuscript of a book, *Analyse des équations déterminées,* and a lengthy memoir when he died in Paris on May 16, 1830.

## Further Reading on Baron Jean Baptiste Joseph Fourier

The most detailed biography of Fourier in English is in François Arago, *Biographies of Distinguished Scientific Men* (trans. 1857). A later biography of Fourier is in Eric Temple Bell, *Men of Mathematics* (1937). The subsequent development and use of Fourier's outstanding contribution to mathematical physics is given in detail in H.S. Carslaw, *Introduction to the Theory of Fourier's Series and Integrals* (1906; 3d ed. 1930). Dirk J. Struik, *A Concise History of Mathematics* (1948; 3d rev. ed. 1967), is recommended for general background.