Jean Victor Poncelet, a French geometrician, born in Metz, July 1, 1788, died in December, 1867. He studied at the polytechnic school, and served as a lieutenant of engineers in the Russian campaign of 1812, when he fell into the hands of the enemy, and was detained as a prisoner at Saratov until the end of the war. He employed his time in researches relating to descriptive geometry, and returned to France with his health greatly impaired. During the next 15 years he was professor at the artillery school in Metz, and subsequently at the Sor-bonne and the college de France; and he was at the head of the polytechnic school from 1848 to 1850, with the rank of general. He bequeathed 2,500 francs to the academy of sciences as a prize for the best work on mathematics. He invented hydraulic wheels known by his name. The academy awarded a prize in 1825 to his treatise entitled Les roues hy-drauliques verticals, d aubes couroes, mues par dessous. His other writings comprise, besides his contributions to Gergonne's Annates de mathematique (1817-'21), treatises Sur les proprietes projeetives des sections coniques, Sur les proprietes projeetives des figures, and Sur les centres des moyennes harmoniques (1822), and Applications d'analyse et de geometrie (2 vols., 1862-'4; revised ed., 1865).