Chasles
# Michel Chasles

### Born: 15 Nov 1793
in Épernon, France

Died: 18 Dec 1880
in Paris, France

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**Chasles** became professor at the École Polytechnique in Paris in 1841. He worked on algebraic and projective geometry. Chasles wrote Apercu historique sur l'origine et le développement des méthodes en géométrie (1837) which is still an important historical reference.
He also wrote an extremely important text on geometry showing the power of synthetic geometry. In his text Traité de géométrie in 1852 Chasles discusses cross ratio, pencils and involutions, all notions which he introduced. In fact Möbius independently introduced the cross ratio. A second text, Traité des sections coniques (1865), applied these techniques to conic sections. The principle of duality occurs throughout his work which was carried on by Steiner.

Chasles was the victim of a celebrated fraud paying the equivalent of 20,000 pounds for various letters from famous men of science and others which turned out to be forged.

**References (5 books/articles)**

**References elsewhere in this archive:**

Tell me about Chasles's work on abstract linear spaces

Michel Chasles was elected to the Royal Society of London in 1854. You can see a history of the Royal Society and a list of the members among the mathematicians in our archive.

He was awarded the Copley Medal of the Royal Society in 1865. You can see a history of the Copley Medal and a list of the winners.

Rue Michel Chasles is in the 12th Arrondissement in Paris. You can see a list of Paris streets named after mathematicians in our archive.

JOC/EFR December 1996