Harrison's Precision Pendulum Clock 2 being dismantled by a clock expert. This clock was the second of three built by the English clockmaker John Harrison (1693-1776). These clocks, made between 1725 and 1728, are said to have been the most accurate in the world at the time. Harrison is famous as the inventor of the marine chronometer that solved the problem of determining longitude at sea. Harrison's number 2 clock is part of the collections of Leeds Museums and Galleries, West Yorkshire, UK.