![]() ![]() Comparing the chronometer's time to local sun time, a navigator could measure longitude with high precision in short order. Over a period of 40 years, he developed four increasingly precise chronometers capable of holding accurate time over a long, rough sea voyage. Enter John Harrison, an apparently self-taught English clockmaker. But the calculations could take hours and were tricky even in the best of circumstances one future astronomer royal, under pressure, botched a measurement of the longitude of Barbados. British astronomers saw a solution in the stars, by making sufficiently accurate measurements of lunar positions and comparing them to positions calculated for a known reference point. ![]() After the loss of many ships and human lives as a result of navigational errors, in 1714 Parliament offered a rich prize for a practical way to measure longitude at sea. ![]() Former New York Times reporter Sobel (coauthor, Arthritis: What Works, 1989, etc.) sets the stage by recounting the difficulties early navigators had in determining their exact longitude. The Greek astronomers could measure latitude as early as the third century b.c., but more than 2,000 years passed before the development of a reliable method for measuring longitude. ![]() The subtitle here tells the reader exactly what the book is about what it doesn't say is how much fun it is to read. ![]()
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