to Chasles, conveying Vrain-Lucas's perspective on these events, itself an invention. In 1986, Alexander Jones published a commentary on Book 7 of the Collection of Pappus of Alexandria, which Chasles had referred to in his history of geometric methods. Jones makes these comments about Chasles, Pappus and Euclid: Chasles's contribution to our comprehension of the Porisms tends to be obscured by the inherent unreasonableness of his claim to have restored substantially the contents of Euclid's book on the basis of the meagre data of Pappus and Proclus...one still turns to Chasles for the first appreciation of the interest in the Porisms from the point of view of modern geometry. Above all, he was the first to notice the recurrence of cross-ratios and harmonic ratios in the lemmas, and because these concepts suffuse most of his restoration, it is probable that many of his inventions coincide with some of Euclid's, even if we cannot now tell which they are. Chasles's name is one of the 72 names inscribed on the Eiffel Tower. Publications M. Chasles (1837) Aperçu historique sur l'origine et le développement des méthodes en géométrie, originally published by Hayez in Bruxelles, now from archive.org. M. Chasles (1841) Two geometrical memoirs on the general properties of cones of the second degree, and other spherical conics, Charles Graves translator, originally published in Dublin, now from Cornell University. M. Chasles (1865) Traité des sections coniques, Gauthier-Villars, from University of Michigan. M. Chasles (1852, 1880) Traité de Géométrie Supérieure, Gauthier-Villars, from Google. See also Chasles–Cayley–Brill formula Chasles's theorem (disambiguation) Asteroid 18510 Chasles Notes References 1793 births 1880 deaths Burials at Père Lachaise Cemetery 19th-century French mathematicians French geometers French historians of mathematics Academic staff of the University of Paris Recipients of the Copley Medal French Roman Catholics École Polytechnique alumni Members of the French Academy of Sciences Lycée Louis-le-Grand alumni Fellows of the American Academy of Arts and Sciences Foreign Members of the Royal Society Foreign associates of the National Academy of Sciences Corresponding members of the Saint Petersburg Academy of Sciences French military personnel of the Napoleonic Wars