The history of longitude is a record of the effort, by navigators and scientists over several centuries, to discover a means of determining longitude.
The measurement of longitude is important to both cartography and navigation. Historically, the most important practical application of these was to provide safe ocean navigation. Knowledge of both latitude and longitude was required. Finding a method of determining longitude took centuries and involved some of the greatest scientific minds.
John Harrison (24 March 1693 â€“ 24 March 1776) was a self-educated English clockmaker. He invented the marine chronometer, a long-sought device in 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 intractable that the British Parliament offered a prize of Â£20,000 (comparable to Â£2.87 million / â‚¬3.65 million / .72 million in modern currency) for the solution.