John Arnold (watchmaker)

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John Arnold (left) with his son and wife. Painting by Robert Davy , around 1775

John Arnold (* 1736 in Bodmin , Cornwall ; † August 25, 1799 in Eltham , Kent ) was a watchmaker and inventor of very reliable marine chronometers . With his work, he made a decisive contribution to the solution of the length problem .

Longitude Act

Because the longitude could not be determined or only very imprecisely, ships and crews were repeatedly lost. You also had to sail considerably longer distances without knowing the longitude. In 1714 the British Parliament therefore offered a reward of 20,000 pounds for a solution to the length problem, a very substantial sum by the standards of the time (a ship then cost around 2,000 pounds). One can determine the degree of longitude, if one knows a reference time of a place of known length, one has to carry a clock which is as accurate as possible on a ship and shows the time of the port of departure throughout the voyage. Any inaccuracy of this watch leads directly to an error in the length calculation.

Inventions

John Arnold significantly improved the watches of that time. He invented a new type of escapement and simplified the clockwork. The chronometers could thus be built cheaply and in large numbers. He also made the first pocket chronometer . Thanks to special precision manufacturing, his watches withstood the harsh conditions of seafaring and ran very precisely. An exact time measurement was possible for the first time and thus the exact determination of the longitude. It was not until 1805, six years after his death, that his services were recognized by the Longitude Commission and half of the money awarded was paid to his son John Roger Arnold .

literature

  • Dava Sobel: Longitude . btb Goldmann Verlag, 1998, ISBN 3442723183
  • Alexander Chalmers: The General Biographical Dictionary . Nichols [et al.], London 1812-1817. 32 volumes
  • George Long : The Biographical Dictionary of the Society for the Diffusion of Useful Knowledge . Longman, Brown, Green & Longmans, London 1842–1844, 4 volumes
  • Charles Knight: Biography . Bradbury, Agnew & Co, London 1856–1872, 7 volumes (The English Cyclopaedia, Division III)

Web links

Commons : John Arnold  - collection of pictures, videos and audio files
personal data
SURNAME Arnold, John
BRIEF DESCRIPTION English watchmaker and inventor
DATE OF BIRTH 1736
PLACE OF BIRTH Bodmin , Cornwall
DATE OF DEATH August 25, 1799
Place of death Eltham , Kent