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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: 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.
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 ...
John Harrison (3 April [O.S. 24 March] 1693 – 24 March 1776) was an English carpenter and clockmaker who invented the marine chronometer, a long-sought-after device for solving the problem of how to calculate longitude while at sea.
The Greek Marinus of Tyre (CE 70–130) was the first to assign a latitude and longitude to every place on his maps. From the late 9th century CE, the Arabian Kamal was used in equatorial regions, to measure the height of Polaris above the horizon. This instrument could only be used in latitudes where Polaris is close to the horizon.
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.
£20,000 for a method that could determine longitude within 30 nautical miles (56 km; 35 mi) (£3,700,000 as of 2023). In addition, the Board had the discretion to make awards to persons who were making significant contributions to the effort or to provide financial support to those who were working towards a solution.
The French Bureau of Longitude established a commission in the year 1897 to extend the metric system to the measurement of time. They planned to abolish the antiquated division of the day into hours, minutes, and seconds, and replace it by a division into tenths, thousandths, and hundred-thousandths of a day.