Harrison, John

Harrison, John (1693–1776). Horologist. From the 15th cent. onwards, when mariners began to make long ocean voyages, the difficulty of estimating the exact longitude at sea had cost the lives of thousands of sailors, most notably of Sir Clowdesley Shovell and his crews off the Scillies in 1707. In 1714 Parliament, in the Longitude Act 12 Anne c. 15, offered a handsome first prize of £20,000 to anyone who could solve the problem. There were two approaches. First was by plotting moon, planets, and stars and observing them: this was difficult in boisterous or stormy weather, and impossible in heavy cloud. The second was to develop an extremely accurate timepiece, which would not be affected by salt water, damp, or violent motion on board, and use it to maintain the time of setting sail for comparison with the time as measured by the sun. Pendulum clocks would not serve since the metal was affected by heat and cold and the swing by the pitching of the vessel. John Harrison, a clock-maker from Foulby near Pontefract in Yorkshire, who later moved to Barrow-on-Humber, devoted his life to making four brilliant clocks, now preserved at Greenwich, and claimed the prize. For 40 years he was frustrated, partly by his own perfectionism, partly by obstruction by his rivals in the astronomic camp, particularly Nevil Maskelyne, appointed astronomer-royal in 1765. In the end the intervention of George III, who had an interest in astronomy, persuaded Parliament in 1773 to allow Harrison his full prize. He was then 80. His clocks were masterpieces of skill, precision, ingenuity, and determination.

J. A. Cannon