Alexis Claude Clairault (or Clairaut), French mathematician, 1763.
© Science Museum / Science & Society Picture Library
Engraving by Delafose after L C DeCarmontel. Clairault (1713-1765) was a child prodigy who understood differential and integral calculus and analytical geometry at nine, and at 13, after research on double curvature curves, was the youngest person ever to be elected as a member of the Paris Academy of Sciences. From 1736-37 he went on an expedition to Lapland to measure a degree of longitude and to verify Newton's theoretical proof that the Earth is an oblate (flattened at the poles) spheroid. He concluded there was an error in Newton's inverse square law and that his theory of gravity in relation to the moon's orbit was incorrect. He gained great public acclaim when he calculated, to within a month, the return of Halley's comet in 1759.