Chasles, MICHEL

Chasles, MICHEL, was born near Chartres on 15th November 1793. He entered the École Poly- technique in 1812, and on leaving was classed among the engineers; but with rare generosity he renounced his place as an officer in order to assure a career to one of his unsuccessful comrades. In December 1829 he addressed to the Brussels Academy a memoir on two general principles of geometry, duality and homography. The introduction to this memoir expanded into the well-known Aperçu historique sur l'Origine et le Développement des Méthodes en Géométrie, the first edition of which was published in 1837. In 1841 he was appointed to the chair of Machines and Geodesy at the École Polytechnique, and in 1846 to that of Higher Geometry, which had just been instituted at the Sorbonne. In 1852 appeared his Traité de Géométrie supérieure; in 1860, Les Trois Livres de Porismes d'Euclide rétablis pour la Première Foix; in 1865, the Traité des Sections Coniques; in 1870, the Rapport sur les Progrès de la Géométrie. These, his principal works, are geometrical and historical. His contributions to the Comptes rendus of the Academy of Sciences and to other scientific publications are extremely numerous, and though in the main geometrical, are not exclusively so. In particular he treated in several memoirs the question of attraction, and gave the first synthetic demonstration of a celebrated theorem of Maclaurin on the attraction of ellipsoids. Two of his memoirs on the properties of cones of the second degree, and on the spherical conics, were translated into English, and published, with additions, by Charles Graves in 1841. The best account of Chasles's writings is that given by himself in the Rapport above mentioned. During his long life he was the recipient of many scientific distinctions, and he will always be cited as one of the great geometers of the 19th century. He died at Paris on 18th December 1880. An unfortunate episode in his life was that of the autographs. In 1867 he reported to the Academy that he had come into possession of autographs of Pascal's which proved that Pascal had anticipated Newton's greatest discoveries. Ultimately, however, he had to admit that these and about 27,000 other autographs (including letters from Julius Cæsar, Dante, and Shakespeare) were forgeries. The forger, Irène Lucas, was convicted and punished.