Jacques Babinet

French physicist, born at Lusignan, Vienne, 5 March, 1794; died at Paris, 21 October, 1872. He began his studies at the Lycée Napoléon. There he became a pupil of Binet, whose influence caused him to abandon the study of law, for which his family had destined him, and to devote himself to the pursuit of science. He continued at the Polytechnic School, which he left in 1812 to enter the Military School at Metz. For some time he was attached to the Fifth Regiment of Artillery, but at the Restoration he left the army and began to teach. He was professor of mathematics at Fontenay-le-Comte, then professor of physics at Poitiers, and later at the Lycée Saint-Louis. From 1825 to 1828 he delivered a course of lectures on meteorology; in 1838 he succeeded Savary at the Collège de France; and in 1840 he was elected to the Academy of Sciences.

His scientific fame rests on his work in optics, although his contributions to science include the other branches of physics and mechanics. He improved the valves of the air-pump, attaining a very high vacuum; he constructed a hygrometer and a goniometer, and invented the Babinet compensator, a double quartz wedge used in the study of elliptically polarized light. "Babinet's theorem" deals with the diffraction of light. He must, however, be chiefly remembered as a great popularizer of science, an amusing and clever lecturer, a brilliant and entertaining writer of popular scientific articles. He fully recognized the limitations of physical science, while his sincere faith showed itself especially at the end, when he passed away with touching resignation, beloved by all for his kindly and charitable nature.

Babinet's contributions to the "Revue des Deux Mondes" and to the "Journal des Débats" and his lectures on observational science before the Polytechnic Association were collected in eight volumes: "Etudes et lectures sur les sciences d'observation" (1855-65). His other serious works include: "Résumé complet de la physique" (Paris, 1825); "Expériences pour vérifier celles de M. Trevelyan" (Paris, 1835). The following four monographs are published in the Memoirs of the Société Philomathique: "Sur la masse de la planète Mercure" (1825); "Sur la couleur des réseaux" (1829); "Sur la détermination du magnétisme terrestre" (1829); "Sur la cause du retard qu'éprouve la lumière dans les milieus réfringents" (1839).

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