19 February 2017 - JOHN HARRISON


G'day folks,

John Harrison was a self-educated English carpenter and clock maker who invented the marine chronometer, a long-sought after device for solving the "longitude problem" - a practical method of calculating longitude while at sea.

 John Harrison was born in Foulby, near Wakefield in West Yorkshire. His father worked as a carpenter, and John followed his father into the carpentry business. He also developed a passion for music and learning how clocks work. It was said, as a youngster, he would take clocks apart and put them back together.

Harrison combined his skills of being a carpenter with making new clocks. Later clocks also added extra features, such as the grasshopper escapement to improve the quality of clocks. The grasshopper escapement provided a controlled and step by set process for releasing the energy of the clock. His pendulum clocks are considered to be some of the most accurate clocks of the age.

Although a good inventor, he was less skilled at dealing with people, Harrison was helped by George Graham and Edmond Halley, who helped finance, encourage and advocate on behalf of Harrison.

 His most important invention was finding a solution to the issue of longitude. For a long time, the ability to know a ship’s longitude position had not been found. Numerous attempts had been made, but none successful. The ability to know longitude was essential to the safe navigation of ships. The problem was considered so important, Parliament offered a £20,000 reward for the first person who could provide a solution. Sir Isaac Newton himself had doubted whether such a device could be created.

Harrison’s invention was to develop a clock able to tolerate fluctuations in temperature and air pressure, and could keep very exact time for a long time. It took Harrison five years to develop his first sea clock (H1). It incorporated roller pinions, wooden wheels and two dumbbell balances linked together. After receiving approval of Royal Society, it was given its first sea trial on a route to Portugal. The tests proved very favourable, with Harrison’s clock accurately predicting longitude (compared to the old methods which were 60 miles out.) However, this was not enough for the Parliamentary prize which required use on transatlantic routes.

 Over the next few years, he built different versions, improving on the design. Changing bar balances to circular balances (not affected by the rolling action of the sea). His next models, H2 and H3 were never entirely successful, and around 1750 Harrison abandoned his Sea Clock, and started working on a smaller sea watch.

Incorporating elements of other watches, built by Thomas Judge, Harrison worked on a Marine watch (H4). Although taking another six years to build, Harrison was able to prove successfully that by using this watch Longitude could be accurately measured. On the first trial to Jamaica, the Marine Watch proved very accurate. However, the Parliament board kept back the prize, arguing that it might have been due to good luck. Harrison had to do other trials, and in the meantime came up with a second sea watch H5. Again, it proved reliable, but again Parliament withheld the full prize. Enlisting the help of the King George III, Harrison was eventually award £8,750 – though by that time he was 80 years old. The full prize was never awarded to anyone.

Harrison’s lifework had been completed after years of hard work on improving the design. It was soon widely used. For example, fellow Yorkshireman Captain James Cook, used a copy of H4 on his second and third journeys. Despite their high cost, they proved very useful for safer navigation.
Harrison died at the ripe age of 83, and was buried in Hampstead. Harrison’s device was later improved upon by John Arnold, who enabled the production of cheaper Chronometer’s – enabling their widespread use in shipping.

Clancy's comment: Amazing, eh? Another inventive man.

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