The Longitude Act

In order for sailors to know exactly where they were at sea, it became increasingly vital to calculate longitude – the ship’s east/ westw position. Accurate pendulum clocks existed from the 17th century but the e movement of the ship, air humidity and temperature badly affected the timepieces. In 1714, the British government issued a competition offering a £20,000 reward for anyone who could come up with a solution to the longitude problem and provide a portable clock accuratee to within three seconds a day – unhe eard of at that time. Enter John Harrison (1693-1776), a joiner/clock maker from Yorkshire who had built his first longcase clock aged 20. The factual but quasi-fictionalised Longitude by Dava Sobel, published by Harper in 1995, depicts his endeavours and was filmed by Granada TV in 2000. The development of his clocks to solve the longitude problem is explained by the Royal Museums s in Greenwich at rmg.co.uk/ exploore/astronomy-and-time/ timme-facts/harrison# longitude.

There was considerably chicanery innvolved in paying him the prize ffund and he had to submit all his cclocks to the commissioners before hhe could receive anything. Having started his work in 1728, he was awwarded £10,000 in 1765 but it toook an appeal to King George III in 17722 before he was finally bestowed a further £8,750 by Act of Parliament in June 1773. Over 23 years, he received a total of £23,065 worth more than £1.25 million today – a prize well worth striving towards.

Examples of his clocks are held at the Science Museum, London, and Nostell Priory, Yorkshire.