Desargues, Girard

Born 1593 in Lyon; died there 1662. (According to other sources, born 1591 and died 1661.) French mathematician; military engineer.

Desargues laid the foundations of descriptive and projective geometry. He systematically used perspective in his studies and was the first to introduce elements at infinity into geometry. One of the fundamental theorems of projective geometry was derived by Desargues (Desargues’s theorem). He is also the author of works on stonecutting and sun dials, where he gave a geometrical foundation to practical activities.