Before revision: Formula Clairaut's formula for the acceleration due to gravity g on the surface of a spheroid at latitude , was :W. W. Rouse Ball A Short Account of the History of Mathematics (4th edition, 1908) where is the value of the acceleration of gravity at the equator, m the ratio of the centrifugal force to gravity at the equator, and f the flattening of a meridian section of the earth, defined as: (where a = semimajor axis, b = semiminor axis).
After revision: Formula Clairaut's theorem says that the acceleration due to gravity g on the surface of a spheroid in hydrostatic equilibrium (being a fluid or having been a fluid in the past, or having a surface near sea level) at latitude is(including the effect of centrifugal force) :W. W. Rouse Ball A Short Account of the History of Mathematics (4th edition, 1908) where is the value of the acceleration of gravity at the equator, m the ratio of the centrifugal force to gravity at the equator, and f the flattening of a meridian section of the earth, defined as: (where a = semimajor axis, b = semiminor axis).