Mathematician:Joseph Louis François Bertrand

French mathematician working in the fields of number theory, differential geometry, probability theory, economics and thermodynamics.

He conjectured Bertrand's Postulate, in 1845, that there is at least one prime between $n$ and $2n - 2$ for every $n > 3$. This was proved in 1850 by Chebyshev, and hence it is also known as the Bertrand-Chebyshev Theorem.

Also wrote plenty on the history of mathematics.

Brother-in-law of Charles Hermite.

Nationality
French

History

 * Born: March 11, 1822, Paris, France
 * Died: April 5, 1900, Paris, France

Theorems and Definitions

 * Bertrand's Postulate, a.k.a. Bertrand-Chebyshev Theorem.

Books and Papers

 * 1843: Surfaces isothermes orthogonale
 * 1845: Mémoire sur le nombre de valeurs que peut prendre une fonction quand on y permute les lettres qu'elle renferme
 * 1849: Traité d'arithmétique
 * 1850: Traité élémentaire d'algèbre
 * 1853: Lagrange's Mécanique analytique (editor)
 * 1855: Méthode des moindres carrés (a translation of Gauss's work on least squares)
 * 1864-1870: Traité de calcul différentiel et de calcul intégral (2 volumes: a third volume was written but the manuscript was destroyed by fire during the political unrest in 1871 and was never rewritten)
 * 1865: Arago et sa vie scientifique (biography of Arago)
 * 1865: Les fondateurs de l'astronomie moderne: Copernic, Tycho Brahé, Képler, Galilée, Newton (biographies)
 * 1867: Rapport sur les progrès les plus récents de l'analyse mathématique
 * 1887: Thermodynamique
 * 1888: Calcul des probabilités
 * 1890: Leçons sur la théorie mathématique de l'électricité
 * 1891: Blaise Pascal (biography)