Clairaut's theorem is a general mathematical law applying to spheroids of revolution. Published in 1743 by Alexis Claude Clairaut in his Théorie de la figure de la terre, tirée des principes de l'hydrostatique, which synthesized physical and geodetic evidence that the Earth is an oblate rotational ellipsoid, it was initially used to relate the gravity at any point on the Earth's surface to the position of that point, allowing the ellipticity of the Earth to be calculated from measurements of gravity at different latitudes.