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 ?0;000 (?.75 million) under the 1714 Longitude Act. Pictures From History