Thomas Earnshaw

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

Life and horological performance

Earnshaw began at the age of 14 years in London apprenticeship as a watchmaker. He also collaborated with John Brockbank (CC ) and opened a manufactory 1785-1790. Around 1780 he had invented a chronometer escapement lever with rest, but it could not afford to patent himself. He therefore struck a deal with a certain Wright, who was waiting for some unknown reason with the patent application, to John Arnold (CC ) has its own chronometer escapement was patented. Due to the striking resemblance between the two inhibitions Earnshaw later accused Brockbank, of having betrayed his chronometer escapement to Arnold. Earnshaw's chronometer escapement was able to prevail against the construction of Arnold as the standard for marine chronometers and was, together with the compensation balance, a commercial success.

Even if they could not solve the length problem, were both Earnshaw and Arnold, 1805 considered by the Board of Longitude for their improvements to the chronometer with larger sums of money. Since then, the chronometer escapement in the construction of Earnshaw and the bimetallic compensation balance were used in almost all marine chronometers. For this reason, Earnshaw is also referred to as the father of the chronometer. Earnshaw sat down to rest in 1822 and handed over the factory to his son Thomas. He had made ​​up to that point about 4,500 watches, including 1,500 bags and marine chronometers.

Alexander von Humboldt used on his trip to Siberia in 1829, next to a pocket chronometer by Abraham Louis Breguet, even such Earnshaw.

Clocks

Although he was really small watchmaker, Earnshaw did not shrink even before the construction of clocks. He designed at the request of the British Nevil Maskelyne Hofastronoms the Transit Clock for the Armagh Observatory in Northern Ireland. The clock had to avoid a number of new features, including an air-tight box dust and drafts. The transit clock has been praised in the 19th century by the Irish astronomer Thomas Romney Robinson ( 1792-1882 ) in the highest tones and called the most accurate clock in the world.

The selling price was £ 100 and Earnshaw calculated further £ 100 for the safe transport to Armagh and installing it in the new observatory. The observatory also bought Earnshaw's second clock winding, which indicated that sidereal time and was operated in conjunction with a telescope on equatorial mount by Edward Troughton ( 1753-1835 ).

Earnshaw's chronometer E520

From 1801 sailed Matthew Flinders, an English explorer, with his ship HMS Investigator the south and east coast of Australia. He was the first complete circumnavigation of Australia. In order to test and to reliably determine the longitude at sea were 5 marine chronometers on board, including the chronometer E520 Earnshaw, who was mounted on gimbals in a wooden box to compensate for the ship's movements. Flinders went regularly to the coast and had to check the progress of the chronometer with the help of a regular clock. On the ship they were aligned with the position of the stars. Earnshaw's chronometer was the only one who was still working at the end of the trip. This led Flinders to call him in his book A Voyage to Terra Australis as an excellent timepiece.

On the way back from Sydney to England came Flinders in 1803 on what was then the French island of Mauritius in captivity. Two years later, a Captain Aken, a companion Flinders, released and allowed to return to England. Flinders gave him the chronometer to take him to the Royal Greenwich Observatory, where he arrived in December 1805. After that lost its track until it was sold in 1937 by an Australian collector at the Powerhouse Museum in Sydney, where he is kept ever since. Only in 1976, however, he was identified as the chronometer, Flinders had accompanied on his historic journey.

Writings

• Longitude, to appeal to the public. London 1808.