Gaspard Monge, French mathematician and engineer (died 1818)

Gaspard Monge, Comte de Péluse was a French mathematician, commonly presented as the inventor of descriptive geometry, technical drawing, and the father of differential geometry. During the French Revolution he served as the Minister of the Marine, and was involved in the reform of the French educational system, helping to found the École Polytechnique.

May 9 is the 129th day of the year in the Gregorian calendar; 236 days remain until the end of the year.