John Harrison, English clockmaker and inventor of the marine chronometer that solved the longitude problem (b. 24 March 1693 - d. 24 March 1776). An engraving by W. Holl in \The Gallery of Portraits\" 1835, with later colouring, from an engraving by Tassaert - itself from a painting by Thomas King 1767. Harrison with his famous watch 'H4' that solved the marine longitude problem by keeping time accurately enough to gauge Greenwich noon during a long voyage. The watch became embroiled in a dispute when the Board, responsible for awarding the longitude prize, took it for further testing. Their concern was that its accuracy was a freak and could not be duplicated by another watch of the same design. Partly this was a result of their own bias towards astronomical methods of longitude reckoning. A copy of H4 (K1) was used on Cook's second and third voyage and he praised its accuracy."