John Crosley (1762–1817) was an English astronomer and mathematician who was an assistant at the

Royal Observatory, Greenwich The Royal Observatory, Greenwich (ROG; known as the Old Royal Observatory from 1957 to 1998, when the working Royal Greenwich Observatory, RGO, temporarily moved south from Greenwich to Herstmonceux) is an observatory situated on a hill in ...

, a computer of the '' Nautical Almanac'', an observer on maritime voyages of scientific exploration and a member and President of the

Spitalfields Mathematical Society The Spitalfields Mathematical Society was founded in 1717 by Joseph Middleton. The society had 64 members when it was established, and at first meetings were held in the Monmouth's Head, a public house in the Spitalfields district of London. Fellow ...

Life

John Crosley was born in Yorkshire, but little is known of his life before his employment as an assistant at the

to the Astronomer Royal, Nevil Maskelyne. He was the Observatory's assistant in 1789–1792 and again in 1798. He was an observer appointed by the

Board of Longitude The Commissioners for the Discovery of the Longitude at Sea, or more popularly Board of Longitude, was a British government body formed in 1714 to administer a scheme of prizes intended to encourage innovators to solve the problem of finding lon ...

between 1793 and 1798 to

George Vancouver Captain George Vancouver (22 June 1757 – 10 May 1798) was a British Royal Navy officer best known for his 1791–1795 expedition, which explored and charted North America's northwestern Pacific Coast regions, including the coasts of what a ...

's expedition to the north-west coast of America, replacing William Gooch, who was murdered in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

. During this voyage his ship, , was wrecked on a reef near

Okinawa is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi). Naha is the capital and largest city ...

, and he returned to England on another sloop. His salary was £400 per annum, but he spent some years seeking compensation from the Board of Longitude for the loss of his books and instruments, ultimately receiving another £400 reward. As a Board-appointed observer he was required to use and care for the instruments with which he was issued. These included three timekeepers made by

Thomas Earnshaw Thomas Earnshaw (4 February 1749 in Ashton-under-Lyne – 1 March 1829 in London) was an English watchmaker who, following John Arnold's earlier work, further simplified the process of marine chronometer production, making them available to the ...

and one by John Arnold. He recorded all his observations and the problems encountered, including giving an account of the ship's wreck. Crosley returned to the Royal Observatory for a few months in the summer of 1798. He was later appointed as observer to

Matthew Flinders Captain Matthew Flinders (16 March 1774 – 19 July 1814) was a British navigator and cartographer who led the first inshore circumnavigation of mainland Australia, then called New Holland. He is also credited as being the first person to u ...

's circumnavigation of Australia (1801–1803), although ill health forced him to return in 1802, having only got as far as the

Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...

. On this voyage he made observations of position, particularly longitude, using both the astronomical lunar-distance method and timekeepers. As well as acting as assistant to the Astronomer Royal at Greenwich, Nevil Maskelyne, Crosley was appointed by him as a computer of the '' Nautical Almanac'', an important source of income from 1799 and for the rest of his life. He was a member of the

for 31 years and became its president from about 1800 until his death in 1817. He was recorded on a Society membership list as living at 54 North Street, City Road and, in a subsequent entry, as at 84 Leonard Street. An engraving of him that was included in a 1813 Mathematical Society Scrapbook records that he was then "13 Years President of the Mathematical Society".

References

{{DEFAULTSORT:Crosley, John 1762 births 1817 deaths 18th-century British astronomers English mathematicians 19th-century British astronomers