Thomas Earnshaw

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Thomas Earnshaw (1749-1829)

Thomas Earnshaw (born February 4, 1749 in Ashton-under-Lyne , † March 1, 1829 in London ) was an English watchmaker who was the first to simplify the construction of marine chronometers so that a wider public could afford such instruments. He is also known for the invention of a chronometer escapement and the bimetallic compensation balance.

Life and horological achievement

Earnshaw began an apprenticeship as a watchmaker in London at the age of 14. There he also worked with John Brockbank ( CC ) and opened a manufactory between 1785 and 1790. Around 1780 he had invented a chronometer escapement with a rest lever, but could not afford to have it patented. He therefore reached an agreement with a certain Wright, who, for some inexplicable reason, waited to apply for a patent until John Arnold (CC) had patented his own chronometer escapement. Because of the striking similarity of the two escapements, Earnshaw later accused Brockbank of having betrayed his chronometer escapement to Arnold. Earnshaw's chronometer escapement was able to prevail against Arnold's design as the standard for marine chronometers and, together with the compensation balance, became a commercial success.

Even though they could not solve the length problem, both Earnshaw and Arnold were given larger sums of money by the Board of Longitude in 1805 for their improvements to the chronometer. Since then, the Earnshaw type of escapement and the bimetallic compensation balance have been used in almost all marine chronometers. For this reason, Earnshaw is also known as the father of the chronometer . Earnshaw retired in 1822 and handed over the manufacture to his son Thomas. By then he had made around 4,500 watches, including 1,500 pocket and marine chronometers.

On his trip to Siberia in 1829, Alexander von Humboldt used a pocket chronometer from Abraham Louis Breguet as well as one from Earnshaw.

Clocks

Earnshaw's Chronometer No. 506, which was used on the HMS Beagle from 1831 to 1836

Although he was actually a watchmaker, Earnshaw didn’t shy away from making clocks . At the request of the British astronomer Nevil Maskelyne, he designed the transit clock for the Armagh Observatory in Northern Ireland . The watch had a number of new features, including an airtight case to prevent dust and drafts. The transit clock was highly praised in the 19th century by the Irish astronomer Thomas Romney Robinson (1792–1882) and called the most accurate clock in the world.

The sale price was £ 100 and Earnshaw charged an additional £ 100 for safe transport to Armagh and installation in the new observatory. The observatory also bought Earnshaw's second clock, which showed the sidereal time and was operated together with a telescope on an equatorial mount according to Edward Troughton (1753-1835).

Earnshaws Chronometer E520

From 1801, Matthew Flinders , an English explorer, sailed the south and east coast of Australia with his ship HMS Investigator . He was the first to succeed in completely circumnavigating Australia. For testing purposes and for the reliable determination of the longitude at sea, 5 marine chronometers were on board, including the Earnshaw E520 chronometer, which was gimbaled in a wooden box to compensate for the ship's movements . Flinders drove regularly to the coast and had the chronometer checked with the help of a regular clock. On the ship, they were compared with the stars. Earnshaw's chronometer was the only one that was still working at the end of the trip. This led Flinders to call it an excellent timepiece in his book A Voyage to Terra Australis .

On his way back from Sydney to England, Flinders was captured on the then French island of Mauritius in 1803 . Two years later, a Captain Aken, one of Flinder's companions, was released and allowed to return to England. Flinders gave him the chronometer to take to the Royal Greenwich Observatory , where he arrived in December 1805. After that, its track was lost until it was sold in 1937 by an Australian collector to the Powerhouse Museum in Sydney , where it has been kept ever since. It wasn't until 1976, however, that it was identified as the chronometer that accompanied Flinders on his historic journey.

The Earnshaw Glacier in Antarctica is named after him in his honor.

Fonts

  • Longitude, an Appeal to the Public . London 1808.

Individual evidence

  1. ^ A b G. H. Baillie, C. Clutton, C. A. Ilbert: Britten's Old Clocks and Watches and their Makers . Bonanza Books, New York (USA) 1956.
  2. ↑ http://www.bridica.com/EBchecked/topic/175942/Thomas-Earnshaw Encyclopaedia Britannica Online
  3. ↑ a b Fritz von Osterhausen: Callweys Uhrenlexikon . Callwey, Munich 1999, ISBN 978-3766713537 .
  4. ↑ # Reinhard Meis: Pocket watches. From the neck watch to the tourbillon . 4th edition. Callwey, Munich 1999, ISBN 978-3766713964 .
  5. ↑ The amount of the sums is stated differently. They range between £ 2,500 and £ 3,000 for Earnshaw and £ 1,672 and £ 3,000 for Arnold's heirs.
  6. ↑ http://www.nmm.ac.uk/collections/explore/object.cfm?ID=BHC2674 Royal Observatory, Greenwich
  7. ↑ Matthew Flinders: A Voyage To Terra Australis; undertaken for the Purpose of completing the Discovery of that Vast Country, and prosecuted in the Years 1801, 1802, and 1803, in His Majesty's Ship the Investigator, and subsequently in the Armed Vessel Porpoise and Cumberlan .
  8. ^ Thomas Tooth: The Earnshaw Chronometer 'a monograph originally published by the Powerhouse Museum of Applied Arts and Sciences , Sydney 1981.

literature

  • Rupert T. Gould: The Marine Chronometer. Its history and development . Antique Collectors' Club Ltd, London 1988, ISBN 978-0907462057 .

Web links

Commons : Thomas Earnshaw  - collection of images, videos and audio files
personal data
SURNAME Earnshaw, Thomas
BRIEF DESCRIPTION English watchmaker
DATE OF BIRTH February 4, 1749
PLACE OF BIRTH Ashton-under-Lyne
DATE OF DEATH March 1, 1829
Place of death London