Self-taught John Harrison spent 43 years overcoming engineering challenges to develop the first marine chronometer. Harrison won a British competition to resolve deep sea navigation problems, but it took him several years to win the full prize.
In 1714, the British government offered a longitude prize for a method of determining longitude at sea, with the awards ranging from £10,000 to £20,000 (£2 million to £4 million in 2019 terms) depending on accuracy. John Harrison, a Yorkshire carpenter, submitted a project in 1730, and in 1735 completed a clock based on a pair of counter-oscillating weighted beams connected by springs whose motion was not influenced by gravity or the motion of a ship. His first two sea timepieces H1 and H2 (completed in 1741) used this system, but he realized that they had a fundamental sensitivity to centrifugal force, which meant that they could never be accurate enough at sea. Construction of his third machine, designated H3, in 1759 included novel circular balances and the invention of the bi-metallic strip and caged roller bearings, inventions which are still widely used. However, H3’s circular balances still proved too inaccurate and he eventually abandoned the large machines.
Harrison solved the precision problems with his much smaller H4 chronometer design in 1761. H4 looked much like a large five-inch (12 cm) diameter pocket watch. In 1761, Harrison submitted H4 for the £20,000 longitude prize. His design used a fast-beating balance wheel controlled by a temperature-compensated spiral spring. These features remained in use until stable electronic oscillators allowed very accurate portable timepieces to be made at affordable cost.
£20,000 in 1714 = ±£3,837,000 in 2018 = ±$4,733,000 USD.
$110k/year is not a bad payoff for a 45 year-long side project. Harrison began as a 21 year-old, and was 66 when he resolved the problem and received the full amount of the prize. He died 17 years later in 1776.
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