On Oct. 21, 1707, a sailor aboard the English warship Association approached his captain, Adm. Clowdisley Shovell. The sailor had kept his own "reckoning," as it was termed, of the ship's position at sea during a recent spate of foggy weather that had made for difficult navigation. He felt certain, he informed Shovell, that the fleet was heading the wrong way.
Shovell had him hanged on the spot for mutiny.
The next day, the Association and the rest of the fleet ran aground on the Scilly Isles, near the southwest tip of England. The wreck left 2,000 dead and two injured, one of the latter being the admiral. Shovell dragged himself ashore and collapsed, shortly after which a local woman discovered and murdered the weakened seaman for his emerald ring.
Some time earlier, sailors had mastered the measurement of latitude, the displacement of distance north or south of the equator, but they had failed to develop a system that could accurately determine longitude, the measure of how far one had traveled east or west. For every year scientists and inventors failed to engineer a method to measure longitude, men would die at sea as a result of poor reckoning, and commerce and progress would be impeded.
Enter John Harrison, a self-taught clockmaker who believed he could create a clock that would be the first to survive the rigors of the sea. Experts agreed that an accurate determination of duration at sea, combined with latitude readings, could pinpoint a ship's location. Harrison succeeded, only to have politics shelve his invention -- for a time.
Author Dava Sobel tells the dramatic story in Longitude, a brief 1995 work of nonfiction. The latest entry from the science-loving Sobel is Galileo's Daughter, a biography of the great scientist told through letters between the man and his daughter, a nun. Like Longitude, the new book is a compelling and emotional journey through scientific discovery.