Jacques de Billy

Jacques de Billy ( born March 18, 1602 Compiègne, † January 14, 1679 in Dijon ) was a French Jesuit, astronomer and mathematician.

De Billy studied at Jesuit colleges in the Champagne and taught mathematics there. For example, he taught 1629/30 in Pont -à -Mousson and studied theology there, and from 1631 to 1633 he taught in Reims. One of his pupils was Claude Gaspard Bachet de there Méziriac. He then taught in Grenoble, Chalons, Langres, Sens and from 1665 to 1668 in Dijon, where Jacques Ozanam was one of his students.

De Billy corresponded with Pierre de Fermat on number theory. A collection of problems from the letters of Fermat with an essay by De Billy on Fermat's number theory was developed by Fermat's son Samuel in the posthumous publication of Diophantus edition of Fermat in 1670 published in the appendix ( Doctrinae analyticae inventum novum ). They allow insight into Fermat's mathematical approach in solving Diophantine equations. De Billy published several mathematical treatises and textbooks.

He also published astronomical tables, as tables of eclipses from 1656 to 1693. He leaned astrology and superstitions that were associated with the appearance of comets, from.

The lunar crater Billy is named after him.

Writings

• Abrégé of préceptes d' algèbre, 1637
• Nova geometricae clavis algebra, 1643
• Tractatus de proportione harmonicae, 1658
• Diophantus geometria immersive opus contextum ex arithmetica geometria et simul, 1660
• The Inventum novelty is in Fermat, Oeuvres, III ( ed. by Paul Tannery ), Paris 1896, pp. 325-398