“ He is famous chiefly as the founder of descriptive geometry (see Geometry) , a science long kept as a Government secret. But he made important contributions to other branches of mathematics as well. The development of modern geometry dates from him; he introduced into analytic geometry of three dimensions a thorough treatment of linear equations, completed the study of surfaces of the second degree which had been begun by Euler, and established the principles of the integration of partial differential equations in connection with the theory of surfaces. ”

“ He was also active in the organization of public education, was one of the first professors in the Ecole Normale, and was one of the founders of the Ecole Polytechnique. He went with Bonaparte to Egypt in 1798, undertook the direction of the Egyptian Institute, and conducted the search for Egyptian antiquities. ”