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Longitude calculations can be simplified using a clock is set to the local time of a starting point whose longitude is known, transporting it to a new location, and using it for astronomical observations. The longitude of the new location can be determined by comparing the difference of local mean time and the time of the transported clock.
Longitude by chronometer is a method, in navigation, of determining longitude using a marine chronometer, which was developed by John Harrison during the first half of the eighteenth century. It is an astronomical method of calculating the longitude at which a position line, drawn from a sight by sextant of any celestial body, crosses the ...
A marine chronometer is a precision timepiece that is carried on a ship and employed in the determination of the ship's position by celestial navigation.It is used to determine longitude by comparing Greenwich Mean Time (GMT), and the time at the current location found from observations of celestial bodies.
Longitude is given as an angular measurement with 0° at the Prime Meridian, ranging from −180° westward to +180° eastward. The Greek letter λ (lambda) [38] [39] is used to denote the location of a place on Earth east or west of the Prime Meridian. Each degree of longitude is sub-divided into 60 minutes, each of which is divided into 60 ...
In the early 1700s, a series of maritime disasters occurred, including the wrecking of a squadron of naval vessels on the Isles of Scilly in 1707. [7] Around the same time, mathematician Thomas Axe decreed in his will that a £1,000 prize be awarded for promising research into finding "true longitude" and that annual sums be paid to scholars involved in making corrected world maps.
Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time is a 1995 best-selling book by Dava Sobel about John Harrison, an 18th-century clockmaker who created the first clock (chronometer) sufficiently accurate to be used to determine longitude at sea—an important development in navigation.
Since local apparent time could be determined with some ease, the problem centred on finding a means of determining (or in the case of chronometers, keeping) the time of the reference place when one is far away from it. For details of the efforts towards determining the longitude, see History of longitude.
The Longitude Act 1714 (13 Ann. c. 14), also known as the Discovery of Longitude at Sea Act 1713, was an act of Parliament of Great Britain passed in July 1714 at the end of the reign of Queen Anne. It established the Board of Longitude and offered monetary rewards ( Longitude rewards ) for anyone who could find a simple and practical method ...