By knowing the shape of our planet we can create maps, survey the oceans, follow rivers, navigate the skies, and travel the globe. This is the story of how we discovered what no one thought possible: the shape of the earth. In 1735, the good ship Portefaix sailed across the Atlantic carrying the world’s first international team of scientists to a continent of unmapped rainforests and ice-shrouded volcanoes. Beset by egos and disease, storms and earthquakes, mutiny and murder, they struggled for ten years to reach the single figure they sought: the length of one degree of latitude. Twenty-five years after the publication of Longitude, this tells the other side of the story, one of our most important geographical discoveries.