TISSERAND, FLIX

born Jan. 13, 1845, Nuits-St.-Georges, Cte-d'Or, Fr. died Oct. 20, 1896, Paris in full Franois-flix Tisserand French astronomer noted for his textbook Trait de mcanique cleste, 4 vol. (188996; Treatise on Celestial Mechanics). This work, an update of Pierre-Simon Laplace's work on the same subject, is still used as a sourcebook by authors writing on celestial mechanics. Before publishing this work, Tisserand had already established his brilliance in his doctoral dissertation (1868), analyzing Charles-Eugne Delaunay's lunar theory, and in his work as director of the Toulouse Observatory (187378). In 1874 he was elected to the Academy of Sciences as a corresponding member and was elevated to full membership in 1878. In 1892 Tisserand was appointed director of the Paris Observatory, and while there he contributed to the production of a still-unfinished international photographic star catalog, the Catalogue photographique de la carte du ciel (Photographic Catalog of the Map of the Sky).