The son of a receiver of taxes at Auxonne, Prieur was an officer in the Engineers at the time of the Revolution, which he joined from its outset. Elected by the _Côte d’Or_ to the Assembly, the Convention, and finally to the Council of the Five Hundred, he sat in all these Assemblies from 1791 to 1793, and distinguished himself by his genuine Republicanism, was for a short time President of the Convention, but after August 10 joined the Army of the Rhine. At the King’s trial he voted for the immediate execution of the accused. Three months later the Convention sent him to Normandy to put down the counter revolutionary projects of the Girondins, who succeeded in arresting Prieur and his brother commissionary, and they remained fifty-one days in the prisons of Caen. On his return to Paris, Prieur became a member of the Committee of Public Safety (August 1793). At the time of the Revolution of 18th Brumaire, Prieur was once more with the army, acting as a colonel in the Engineers, but being too republican to serve the First Consul, he in 1800 retired from military service. He was one of those few among the revolutionists who was an admirable organiser and a practical man. He worked heart and soul for the re-establishment of Public Instruction, and together with Mouge helped to found the _École Polytechnique_. Prieur was the author of the great reform in the metric system. PRONY, GASPARD CLAIR FRANÇAIS MARIE RICHE DE. Born, 1755; died, 1839. One of the greatest engineers of France. In 1787 he commenced the bridge, first called _Pont Louis XVI._, and now _Pont de la Concorde_, which was completed in 1791, when Prony was appointed chief engineer of France. The same year he undertook the composition of new tables of trigonometry adapted to the decimal division of the circle. Prony completed his work in three years, and in 1798 became the Director of the _École des Ponts et des Chaussées_ and professor of mechanics and mathematics at the _École Polytechnique_. Bonaparte made every effort to induce Prony to abandon this appointment and accompany him to Egypt, but was unsuccessful. During the Consulate and Empire, Prony’s word was considered law in all that concerned civil engineering in France, and after the restoration he retained his post at the _École Polytechnique_. In 1818 he was sent to Italy to carry out improvements in the Ports of Genoa, Pola, and Ancona, and to give an opinion upon the possible regularisation of the course of the Po, and in 1827 he carried out works which successfully stopped the annual floods in the Rhone valley, for which service Charles X. created him a Baron. He died at the age of eighty-four. LA REVEILLIÈRE, LOUIS MARIE. Born, 1753; died, 1824.