John Harrison

John Harrison (– 24 March 1776) was a self-educated English carpenter and  clockmaker who invented the marine chronometer, a long-sought after device for solving the problem of calculating longitude while at sea. His solution revolutionized navigation and greatly increased the safety of long-distance sea travel. The problem he solved was considered so important following the Scilly naval disaster of 1707 that the British Parliament offered financial rewards of up to £20,000 (£) under the 1714 Longitude Act. Harrison came 39th in the BBC's 2002 public poll of the 100 Greatest Britons.