This book tells the story of an international scientific expedition during the European Enlightenment to measure the length of a degree of latitude at the equator, and to thereby determine the exact shape of the earth. The leaderships in France and her ally Spain put together an expedition to travel to the equator and measure a degree of latitude there; compared with the degree already measured in Paris, this new measurement would yield the exact shape of the earth. The Geodesic Mission to the Equator departed for colonial Peru (modern-day Ecuador) in 1735, with a motley team that included three French scientists, two Spanish naval officers and their assistants. When the expedition finally returned almost ten years later--battered by even more unexpected hardships and self-inflicted tragedies--all of Europe was waiting with bated breath. Using their measurements, the scientists successfully revealed the true figure of the Earth: a slightly flattened sphere, a conclusion that vindicated Newton's followers.