Harrison John

Harrison, John (1693-1776), inventor of the marine chronometer, was the son of a Yorkshire carpenter. He received little education, and soon began to help his father. In 1726 he invented the "gridiron pendulum." His first chronometer was finished in 1735, and was tested in a voyage to Lisbon. A second was constructed four years later, a third in 1749, and a fourth in 1759. By this it was proved in a voyage to Barbadoes in 1764 that the longitude could be determined within 10 miles, but the Admiralty did not award the inventor the promised premium of £20,000 until in 1775 a fifth watch had been made. The first four are to be seen at the Greenwich Observatory. The Principles of Mr. Harrison's Timeleeeper, with plates and preface by Maskelyne, appeared in 1767.