CHASLES, Michel.

Autograph Letter Signed, to William Spottiswoode (physicist, 1825-1883), inviting Spottiswoode and his wife to dine, and discussing the tickets for an Academy event. In French. 1 page 8 x 5 inches, black borders, fine. Paris, 11 November 1873.

Michel Floréal Chasles (1793 – 1880),  French mathematician. In 1837 he published the book Aperçu historique sur l'origine et le développement des méthodes en géométrie ("Historical view of the origin and development of methods in geometry"), a study of the method of reciprocal polars in projective geometry. Chasles's description of a Euclidean motion in space as screw displacement was seminal to the development of the theories of dynamics of rigid bodies. Chasles was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1864.[5] In 1865 he was awarded the Copley Medal.