Poncelet, Jean Victor

SUBJECT AREA: Mechanical, pneumatic and hydraulic engineering

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b. 1 July 1788 Metz, France

d. 22 December 1867 Paris, France

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French mathematician and military and hydraulic engineer.

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Poncelet studied mathematics at the Ecole Polytechnique in Paris from 1807 to 1810. He joined the Army, gaining admission to the Corps of Engineers. He worked on the fortifications on the Isle of Walcheren in Holland, and in 1812 he found himself on the Russian front, engulfed in the disastrous defeat of the French at Krasnoi. Poncelet was left for dead on the field, but he was found by the Russians and taken to Saratov, where he was imprisoned for two years. He had ample opportunity there to ponder mathematical problems, a mental process from which stemmed his pioneering advances in projective geometry.

After his release he returned to this native city of Metz, where he undertook routine military engineering and teaching tasks. These left him time to pursue his mathematical studies in projective geometry. This bore fruit in a series of publications, most notably the first volume of his Traité des propriétés projectives des figures (1822, Paris), the first book to be devoted to the new discipline of projective geometry. With his election to the Académie des Sciences in 1834, Poncelet moved to Paris and devoted much of his time to developing courses in applied mechanics in the Faculty of Science, resulting in a number of books, especially the Introduction à la mécanique industrielle, physique ou expérimentale (1841, Paris: Metz). In 1848 he had attained the rank of general and was made Commandant of the Ecole Polytechnique, a post he held for two years. After his retirement in 1850 he was deeply involved in the industrial machines and tools division at both the Great Exhibition in London in 1851 and the similar exhibition in Paris in 1855.

Most of Poncelet's work in applied mechanics and technology was conceived during the period 1825–40. His technological innovations were centred on hydraulic engineering, and in 1826 he invented an inward-flow turbine. At the same time he directed his attention to the vertical undershot water-wheel, with wooden blades set radially and substituted curved metal blades: he used tight-fitting masonry and floors in the wheel pits so that all the water would be swept into the spaces between the blades. In addition, he ensured that the water flowing from the blades fell clear of the wheel and did not run in tail water. This greatly improved the efficiency of the water-wheel.

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Bibliography

H.Tribout, 1936, Un Grand Savant: le général Jean-Victor Poncelet, Paris, pp. 204–20 (the most complete list of his published works).

Further Reading

I.Didion, 1870, "Notice sur la vie et les ouvrages du général J.-V.Poncelet", Mémoires de l'Académie de Metz 50:101–59.

M.Daumas (ed), 1968, Histoire des techniques, Vol. 3, Paris (briefly describes his technological work).

LRD