|Place of work
|16 Jul 1789 – 01 Apr 1792 & 21 Jul – 22 Sep 1798
Born in Yorkshire, Crosley did two stints as Maskelyne’s assistant. He first arrived at the Observatory in 1789 as a replacement for William Smith, staying rather longer than either him or the previous eight individuals who had come and gone in quick succession since Maskelyne parted company with Joseph Lindley at the end of September 1786. When he resigned in 1792, he was replaced by Benedict Chapman.
From 7 December 1793, he was employed by the Board of Longitude to replace William Gooch who had been appointed as astronomer to George Vancouver’s expedition to the north-west coast of America and subsequently been murdered while ashore in May 1792. On 16 May 1797 Crosley’s ship, HMS Providence struck a coral reef and sank. Crosley transferred to an accompanying sloop, arriving back in England ahead of the rest of the party on 7 July 1798. He subsequently made a second voyage as astronomer for the Board of longitude, this time, with Captain Flinders on his 1801–3 trip to Terra Australis on the Investigator. During this trip, he fell ill and was set down at the Cape of Good Hope in 1802 from where he returned to England in 1803 and settled in London. His salary for each trip was £400 a year; considerably more than the £96 a year he had earned as Maskelyne’s assistant at Greenwich.
During the gaps between the two voyages, he not only returned to the Observatory for a couple of months to act as Maskelyne’s assistant, he also did work for him as a Computer on the Nautical Almanac, continuing this work after his return from the Cape. His return to the Observatory as an assistant appears to have been to help Maskelyne plug a gap following the departure of Thomas Evans in 1798. He took over from another former assistant William Garrard who had been helping Maskelyne out for the previous three weeks and was replaced on 22 September by Robert Wallace. He was President of the Spitalfields Mathematical Society from 1805 until his death.
Correspondence relating to John Crosley’s claims for payment for an expedition to the north-west coast of America to make nautical, astronomical and trigonometrical observations for the Navy. Board of Longitude papers (from Cambridge Digital Library)