Yvon_Villarceau

Antoine-Joseph Yvon Villarceau (15 January 1813 – 23 December 1883) was a French astronomer, mathematician, and engineer.
He constructed an equatorial meridian-instrument and an isochronometric regulator for the Paris Observatory.
He wrote Mécanique Céleste. Expose des Méthodes de Wronski et Composantes des Forces Perturbatrices suivant les Axes Mobiles (Paris: Gauthier-Villars, 1881) and Sur l'établissement des arches de pont, envisagé au point de vue de la plus grande stabilité (Paris: Imprimerie Impériale, 1853).
He is the eponym of Villarceau circles, which are two circular sections of a torus other than the two trivial ones.
A short street in the 16th arrondissement of Paris is named after Villarceau.