Jacques de Billy

Jacques de Billy was a French Jesuit mathematician, born in Compiègne on 18 March 1602 and dead in Dijon on 14 January 1679. He taught mathematics at the Jesuit colleges of Pont-à-Mousson from 1629 and Rheims from 1631, where his pupil Claude Gaspard Bachet de Méziriac became a close friend and introduced him to indeterminate analysis, and from 1665 at Dijon, where Jacques Ozanam was among his pupils. He also served as rector of Jesuit colleges at Châlons, Langres and Sens. He corresponded with Pierre de Fermat, and his Doctrinae Analyticae inventum novum, drawn from that correspondence, was printed in the 1670 edition of Diophantus with Fermat's notes, helping to make Fermat's number-theoretic methods known. His books include an Abregé des Preceptes d'Algebre of 1637, a Nova Geometriae Clavis Algebra of 1643, Diophantus Redivivus and the eclipse tables Tabulae Lodoicaeae of 1656, and in 1665 he argued that comets are natural events open to scientific study.