Greenwich Mean Time
Greenwich Mean Time (GMT) refers to the mean solar time at the Royal Observatory in Greenwich, London, which became adopted as a global time standard. Coordinated Universal Time (UTC) is arranged so...
Greenwich Mean Time - Wikipedia
History of longitude
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 ...
History of longitude - Wikipedia
Marine chronometer
A marine chronometer is a clock that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation. When first...
Marine chronometer - Wikipedia
John Harrison
John Harrison (3 April  [O.S. 24 March] 1693– 24 March 1776) was a self-educated English carpenter and clockmaker. He invented the marine chronometer, a long-sought after device for...
John Harrison - Wikipedia
Geodesy
Geodesy (/dʒiːˈɒdɨsi/), — also known as geodetics or geodetics engineering — a branch of applied mathematics and earth sciences, is the scientific discipline that deals with the measurement and repre...
Geodesy - Wikipedia