Gaspard Monge solved a week-long fortress problem with drawings in two days
Military engineers at Mézières expected a fortification calculation to take a week. Gaspard Monge, a merchant's son barred from the officer school because he was not noble, handed back an answer in two days using geometry on paper. His superiors first refused to believe it, then adopted his method.
Monge was born in Beaune on 9 May 1746 and was teaching physics at a Lyon college by seventeen. Back home in 1764 he drew a large-scale map of Beaune, inventing both the surveying methods and the instruments, and the town still keeps it in its library. An engineering officer who saw it recommended him to the royal engineering school at Mézières, where he was hired as a draftsman, since only aristocrats could enrol as students.
The task that made his name was défilement: arranging a fort's walls so attackers firing from raised positions could not see into defended spaces or rake a wall along its length. Vauban had proposed measuring this slowly by hand, and the accepted calculation took a week. Monge's graphical solution became the basis of descriptive geometry, and the historian L. T. C. Rolt credited him with the birth of engineering drawing. He replaced the mathematician Charles Bossut at the school in 1769.
Marriage in 1777 to Cathérine Huart, owner of a forge, drew him into metallurgy, and in 1780 he joined the French Academy of Sciences. A 1781 memoir on moving earth efficiently is the earliest known anticipation of the optimal transport problem, later rediscovered by L. V. Kantorovich among others. He also gave the general theory of curvature lines on surfaces, making him a father of differential geometry.
A strong backer of the Revolution, he served as Minister of the Navy from August 1792 to April 1793 and helped found the École Polytechnique, where he taught descriptive geometry. He befriended Napoleon in Italy, joined the expedition to Egypt, and became Comte de Péluse. He died on 28 July 1818; his remains now lie in the Panthéon, and his name is among the 72 engraved on the Eiffel Tower.
Source: Gaspard Monge
