André, Charles Louis Fran

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André, Charles Louis François

(b. Chauny, Asine, France, 18 March 1842; d. St. GenisLavel, Rhône, France, 6 June 1912), astronomy, meteorology.

André worked on observational techniques for determining the distance to the sun—the problem of the solar parallax. In this connection he headed a French expedition sent to Nouméa in 1874 to observe a transit of Venus. Difficulties encountered in timing the transit led him to investigate sources of instrumental error. In later years he compiled statistics on the weather and climate of Lyons.

In 1864 André graduated from the École Normale Supérieure in Paris with a degree in physics. After teaching for a year in Nevers, he returned to Paris as an assistant astronomer under Urbain Leverrier, then director of the Paris Observatory.

His interest in methods of evaluating the solar parallax was shown in two papers written to acquaint French astronomers with work being done in this field by their colleagues in other countries. The first, “Sur la parallaxe du soleil déduite des observations méridiennes de Mars en 1862,” was a summary of a cooperative effort, organized by Friedrich Winnecke, to measure the sun’s distance by making meridian observations of Mars simultaneously from different latitudes on earth during the favorable opposition of 1862. The second, “Sur l’emploi des petites planètes pour la détermination de la parallaxe du soleil,” discussed the merit of Johann Galle’s suggestion that serial observations of asteroids would be even more profitable.

André was willing to go along with the majority, who favored observations of Venus made from widely separated places on earth on the approaching rare occasion when that planet would pass directly between earth and sun. But the failure in both 1761 and 1769 of France’s previous attempts, made by Guillaume le Gentil de la Galaisière, reminded him how vulnerable the observing of so brief an occurrence as a transit could be. André therefore advocated a second program with asteroids. All that came of this was that André was chosen to head a Venus expedition and went to the French possession of New Caledonia for the transit of 9 December 1874. His results, when combined with those obtained in St. Paul, Minnesota, led to a solar parallax of 8.88”. This figure does not compare very favorably with the best modern value of 8.79415”. determined in 1961 by timing radar echoes from Venus, but André felt—as is now generally recognized—that he had isolated one major source of error: his observations led him to believe that the troublesome black drop effect, observed telescopically when the disc of Venus approached inner tangency with the solar limb, had its source in the instrument itself. He therefore investigated the effects of diffraction in optical instruments. With this works as his thesis, André was awarded a doctor’s degree by the Sorbonne in 1876. He went to Ogden, Utah, to test his results at the transit of Mercury of 6 May 1878, but a snowstorm intervened.

On his return to France, André became a professor in the University of Lyons and director of the Lyons Observatory, for which he chose a new site at St. Genis-Laval. Here he spent the remaining thrity-four years of his life. He was a corresponding member of the Académie Française and of the Bureau des Longitudes.

BIBLIOGRAPHY

I. Orginal Works. André’s works include “Sur la parallaxe du soleil déduite des observations méridienns de Mars en 1862,” in Bulletin des sciences mathématiques et astronomiques, 2 (1871), 89–96; “Sur l’emploi des petites planètes pour la déterminition de la parallaxe du soleil,” ibid., 3 (1872), 274–278; L’astronomie pratique et les observatoires en Europe et en Amériue, depuis le milieu du 17e siècle jusquʿà nos jours, 5 vols. (Paris, 1874–1878), Vols. III and IV written with A. Angot, Vol. V with G. Rayet and A. Angot; “Sur les documents scientifiques recueillis à Nouméa par la mision envoyée pour oberver le passage de Vénus,” in Comptes rendus de l’Acdémie des Sciences (Paris), 80 (1875), 1282–1285 and 1599; his thesis, “Diffraction dans les instruments d’optique; son influence sur les obsevations astronmiques,” in Annales scientifiques de lʾÉcole Normale Supérieure, 2nd series, 5 (1876), 275-354; “Sur le passage de Vénus de 9 december 1874,” in comptes rentus de l’Académie des Science (Paris), 82 (1876), 205–208; “Resultats des obsevations du passage de Mercure, Ogden, Utah,” ibid., 86 (1878), 1380–1383; also several texbooks and works on meterology, includeing Recherches sue le climat du Lynnais (Lyosn, 1880); and Relations des phenomènes météorologiques déduites de leurs variations diurnes et annueles (Lyons, 1892). His papers, with the exception of a few published in Comptes rendus de l’Académie des Sceience (Paris) after 1900, are listed in the Royal Socity of London’s Catalogue of Scientific papers, Vol. VII (London, 1877), Vol. IX (London, 1891), and Vol. XIII (Cambeige, 1914), where he is mistakently identified as “l’abbé Charle André.”

II. Secondary Literature. An obituary, with portrait, appeard in Bulletin de la Société des Amis de l’Université de Lyon (1911–1912), 171–184; another, also in French, in Astronomische Nachrichten, 192 (1912), no. 4595. cols. 187–188.

Sally H. Dieke

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