H5,marine chronometer. This timepiece was completed in 1770 by John Harrison (1693-1776),British instrument maker. In 1713,the British Government offered a prize of £20,000 to the maker of the first truly accurate chronometer for ships. These were vital to navigation,as it was the only means of determining longitude with any precision. Harrison built five chronometers,each more accurate than the last and far better than the Government's specifications demanded. The fifth version,seen here,was more accurate at sea than any other clock on land. It was tested by King George III,gaining only 4.5 seconds in 10 weeks,and Harrison eventually received his prize |