Jean Nicolas Pierre Hachette (1769-1834), French mathematician. Hachette was born at Mezieres and was the son of a bookseller. He was educated at Charleville and Reims before taking a post as draughtsman at the school of engineering in his home town. In 1793 he became professor of hydrography and started studying geometrical solutions to problems in navigation. This brought him to the attention of Gaspard Monge, who arranged for a post in Paris. Hachette taught descriptive geometry at the Ecole Polytechnique, his students included Poisson, Arago and Fresnel. His own researches brought geometrical concepts to bear to solve problems in engineering and even the arts. He lost most of his posts during the restoration of the monarchy in 1816, but retained the professorship in the science faculty of the Ecole Normal. After the 1831 revolution he was elected to the Academie des Sciences.