French mathematician and astronomer, b. 16 April, 1820, at Argenteuil (Seine-et-Oise); d. 9 September, 1883, at Frontenay (Jura). He went to school at Pont-à-Mousson (Lorraine). His brother persuaded the family to send the boy to a boarding-school in Paris (1834). In a year's time he entered the Collège Rollin, where he studied mathematics under Sturm. He took the competitive examinations of the Paris lycées and, having won the prizes in mathematics and physics, he was admitted to the Ecole Normale in 1837. Three years later he was appointed associate professor in science and in 1841 received the degree of doctor in mathematical sciences and the appointment to teach at the College of Rennes. In 1845 he was called to the new University of Besançon, where he taught science until 1849. He then returned to Paris as maître de conférences at the Ecole Normale. He substituted repeatedly both at the Sorbonne and at the Collège de France, lecturing for Sturm, Le Verrier, and Binet. In 1853 and 1854 he had charge of the examinations for admission to the polytechnic school. From 1855 to 1859 he was assistant astronomer at the Paris observatory, placed at the head of the bureau of calculation by Le Verrier. From 1857 until six months before his death Puiseux was the successor of Cauchy in the chair of celestial mechanics at the Sorbonne. He resigned, but was granted the right to keep his title. He also gave up his appointment as member of the Bureau des Longitudes (1868-1872), on account of failing health.
Puiseux excelled especially in mathematical analysis. In his account of algebraic functions, first published in the "Journal de Liouville" (1851), he introduced new methods, marking an epoch in this subject. His numerous contributions to celestial mechanics have considerably advanced knowledge in this direction. He supervised the new edition of Laplace's works, published under the auspices of the Academy of Sciences, revising all the formulæ and scrupulously verifying all his calculations in celestial mechanics. He performed a great deal of dry and labourious work himself, such as the reduction of the observations on the moon at Paris during the years 1801-29, and the intricate computations and deductions from the observations on the transit of Venus in 1874 and again in 1882. He had also a decided taste for botany and natural sciences in general. He was fond of philosophy and the classics.
While a student at the normal school he took part in the religious discussions of the day, displaying strong convictions and a keen intelligence. He seconded the efforts of his friend and comrade in the school, Pierre Olivant, founding with him a Society of St. Vincent de Paul among the students and devoting a large part of his vacations to works of charity. His kindness, his charity, and above all his simple, unaffected modesty overshadowed even his talents. His election (1871) to the French Academy was unanimous. Bertrand says of it: "The election was due to his merit, but its unanimity, to his character ". As a last wish he requested that no discourse should be held over his body. His profound faith helped him to bear with resignation the death of a devoted wife and of four grown children. A great number of his memoranda are to be found in "Journal des Savants", "Journal de Liouville", "Comptes Rendus", "Recueils des savants étrangers", "Annales de l'Observatoire de Paris ". He edited "Connaissance des Temps" (Paris) from 1868 to 1872 and from 1864 with Bertrand "Annales scientifiques de l'école normale supérieure".
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