Longitude
Videos
Longitude is a geographic coordinate that specifies the east-west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees
The clockwork in John Harrison's H4 marine chronometer on display at the Royal Observatory, Greenwich
Marine sandglass MMM
History of longitude
Videos
The history of longitude describes the centuries-long effort by astronomers, cartographers and navigators to discover a means of determining the longitude of any given place on Earth. The measurement
Longitude
…Great-circle distance History of longitude The Island of the Day Before…
Monuments of International Longitude Determination at Sheshan Observatory, Shanghai
John Flamsteed's mural arc. The telescope was mounted on a frame with a radius of about 2 metres. It was attached to a wall aligned to the meridian. There was rackwork and a micrometer, which are not shown.
A Transit Instrument from 1793
Galileo's celatone (2013 replica)