Background

Charles Louis François André was born on March 14, 1842, in Chauny, Aisne, France. He was a son of Louis Alexandre François André, who was a watchmaker, and Placidie Godet.

Education

First Charles André studied at the Institution Saint-Charles, then in 1864 he graduated from the École Normale Supérieure in Paris with a degree in physics.

Career

After teaching for a year in Nevers, André 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 modem 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 eifect, 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 work 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 thirty-four years of his life. He was a corresponding member of the Académie Française and of the Bureau des Longitudes.

He died on June 6, 1912 in St. Genis-Laval, Rhone, France.

Achievements

• André`s chief achievement was in founding the Observatory of Lyon of which he was a director from 1878 to 1912 . He also achieved a remarkable success working on observational techniques for determining the distance to the sun—the problem of the solar parallax. The result of such investigation was shown in two papers that made a significant impact on his colleagues in other countries. The first paper is titled, “Sur la parallaxe du soleil déduite des observations méridiennes de Mars en 1862,” was about measuring 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. In this connection he headed a French expedition sent to Nouméa in 1874 to observe a transit of Venus. During such observations Andre made another achievements investigating the effects of diffraction in optical instruments, and with this work as his thesis, he was awarded a doctor’s degree by the Sorbonne in 1876.
  
  

Works

More photos

• book

  • L'astronomie pratique et les observatoires en Europe et en Amérique
  • Relations des phénomènes météorologiques déduites de leurs variations diurnes et annuelles
  • Les planètes et leur origine
  • Cours De Physique À L'usage Der Élèves De La Classe De Mathématiques Spéciales
  • Traité d'Astronomie Stellaire

• Other Work

  • L'astronomie Pratique Et Les Observatoires En Europe Et En Amérique, Depuis Le Milieu Du Xviie Siècle Jusq'à Nos Jours

Connections

Father:

Louis Alexandre François André

Mother:

Placidie Godet

collaborator:

Friedrich August Theodor Winnecke

He collaborated with Andre on his publication "Sur la parallaxe du soleil déduite des observations méridiennes de Mars en 1862.”

References

• Dictionary of Scientific Biography