Antoine-Joseph Yvon Villarceau (1813 – 1883) was a French

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

, mathematician

Mathematician

A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

, and engineer

Engineer

An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...

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He constructed an equatorial meridian-instrument and an isochronometric regulator for the Paris Observatory

Paris Observatory

The Paris Observatory is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world...

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He wrote Mecanique Celeste. Expose des Methodes 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

Villarceau circles

In geometry, Villarceau circles are a pair of circles produced by cutting a torus diagonally through the center at the correct angle. Given an arbitrary point on a torus, four circles can be drawn through it. One is in the plane parallel to the equatorial plane of the torus. Another is...

, which are two circular sections of a torus

Torus

In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...

other than the two trivial ones.