The Magic of Cornwall
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John Arnold 1736 - 1799

John Arnold was born in Bodmin in 1736 and was apprenticed to his father at an early age as a watchmaker. Their place of work was at what is now known as Arnold´s Passage, just off the Fore Street in Bodmin, where a commemorative plaque has been erected. A quarrel between the two led to the ending of their partnership and John left the county, moving initially to The Hague in Holland and then to London in 1756.

He started to gain a reputation as a maker of fine timepieces and was eventually introduced to Court. In 1764 he constructed the smallest ever repeating and striking watch, which was set into a ring and presented to King George III as a gift. Because of the innovative design and the intricacy of the work involved he had to make many of the tools needed himself. He was reputed to have been paid 500 guineas for its manufacture.

John Arnold next turned his attention to the manufacture of more accurate timepieces and invented one of such quality and reliability that Captain James Cook used it on his South Sea Voyages 1772 ­ 1775. One of the most innovative design features was the temperature compensation using a bi-metallic strip. He also solved the problem of friction in the balance spring.

He set up a factory in Chigwell and farmed out part of the production to outworkers and made most of the complicated parts himself. In 1788 he produced the first Pocket Chronometer which so impressed the Astronomer Royal that he decided to test it himself at Greenwich . The watch, no. 1/36 went so well in trials that he decided to give it a new name, that of chronometer and was thus the first person to use that term in its modern sense.

The greatest scientific quest at this time was to find a solution to the problem of calculating longitude aboard ships and the race was on to produce an accurate marine chronometer. There is some controversy about Arnolds contribution to the solution and his work was only recognized by the Board of Longitude after his death, when in 1805 after legal wrangles with his rival Earnshaw his son was awarded the sum of £3000.

His son John Roger Arnold was born in 1769 and was apprenticed to Breguet of Paris, a contemporary of Arnold and possibly the leading watchmaker of his day. Arnold and Breguet held each other in such high regard that they exchanged sons as apprentices. John Roger Arnold continued and improved on his fathers work and together they founded the firm of J. Arnold & Son between 1787 and 1799, whose name survives today, renowned for the production of precision watches and chronometers.

John Arnold was the leading chronometer maker of his day, his contribution to solving the problem of measuring longitude was very important and he was responsible for many improvements to the manufacture of watches and chronometers.

He died in 1799 at the age of 63 and is buried in Chislehurst, Kent.


National Maritime Museum and the race to find a reliable Marine Chronometer