Offprint from the Bulletin of Mathematical Sciences, 2nd series, TIII, 1879
Gaston Darboux (1842-1917) is a French mathematician, he succeeds in 1878 to Chasles at the chair of geometry superior of the faculty of sciences of Paris.
references: Françoise Pécaut [Quadrilatères articulés. Journées nationales APM 1997. p.16 : le théorème de Darboux].