John Harrison (1693 1776) was a self-educated English carpenter and clockmaker. He invented the marine chronometer, a long-sought after device for solving the problem of establishing the East-West position or longitude of a ship at sea, thus revolutionising and extending the possibility of safe long-distance sea travel in the Age of Sail. The problem was considered so important, that the British Parliament offered financial rewards of up to ?20,000 (?2.75 million) under the 1714 Longitude Act.