Wednesday 28 December 2016

Royal Observatory, Greenwich

The Royal Observatory, Greenwich  is an observatory situated on a hill in Greenwich Park, overlooking the River Thames. It played a major role in the history of astronomy and navigation, and is best known as the location of the prime meridian.
The observatory was commissioned in 1675 by King Charles II, with the foundation stone being laid on 10 August. The site was chosen by Sir Christopher Wren. At that time the king also created the position of Astronomer Royal, to serve as the director of the observatory and to "apply himself with the most exact care and diligence to the rectifying of the tables of the motions of the heavens, and the places of the fixed stars, so as to find out the so much desired longitude of places for the perfecting of the art of navigation." He appointed John Flamsteed as the first Astronomer Royal. The building was completed in the summer of 1676. The building was often called "Flamsteed House", in reference to its first occupant.
The scientific work of the observatory was relocated elsewhere in stages in the first half of the 20th century, and the Greenwich site is now maintained as a museum.






By 1700, skilled seamen could find their position north or south (their latitude), but still lacked accurate instruments or methods to calculate their east-west position, known as longitude.
With growing international trade, the lives and valuable cargoes lost in shipwrecks made solving this problem of longitude urgent for all sea-going nations.




John Harrison's H4 is the most important timekeeper ever made. It is the machine that helped solve the problem of keeping accurate time at sea and finally won Harrison huge rewards from the Board of Longitude and the British Government. H4's high-energy watch balance was less affected by the movement of a ship and was the design breakthrough that Harrison needed. He believed his fourth timekeeper was the most perfect and beautiful machine ever constructed. H4's predecessors H1, H2 and H3 are all also on display in Time and Longitude.




























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