Whose measurements helped prove that the Earth is not a perfect sphere?

Maupertuis led a famous scientific expedition to Lapland in 1736–1737 to measure a degree of latitude near the Arctic Circle. The results supported Isaac Newton’s prediction that Earth is an oblate spheroid, flattened at the poles and wider at the equator. This was an important test of Newtonian physics against rival ideas. The expedition combined field surveying, astronomy, and geometry. It became one of the landmark geodesy projects of the Enlightenment.