Measure of the Earth

April 11, 2011
Science writer Ferreiro (Ships and Science) recounts exhaustively a joint (at least in name if not in spirit) 1735 expedition of France and Spain designed to discover the size and shape of the Earth. Expected to take two years, the expedition to what is now Peru, where the expeditioners would calculate the measure of a degree of latitude at the equator, lasted almost a decade. It's impossible not to be impressed with the operation's technical achievement while reading the author's fascinating and clearly written account of the complex astronomical tools and methodology employed. Equally impressive are the myriad examples of interpersonal dysfunction, political intrigue, and wasted efforts that Ferreiro recounts with straightforward enthusiasm. For example, at one point the scientists are forced to discard two years of astronomical calculations that turned out to be inaccurate. But the mission was ultimately successful and made a scientific star of its de facto leader, Pierre Bouguer, and a celebrity of another, Charles Marie de La Condamine. Despite some dense but clearly explained scientific material, readers will be drawn in by the personalities and trials of the ambitious expedition. Maps.