His ship, HMS Dorothea, was charged to sail northwards across the pole to the Bering Strait in the belief that the polar ice had retreated.
The Dorothea and consort Trent reached their rendezvous at northwest Spitsbergen and set sail northwards on 7 June 1818.
He was then recommended by the Royal Society to be the astronomer for Captain William Parry’s second attempt to find a north-west passage.
He also measured the velocity of sound, the contraction of a series of different metal bars at low temperatures, and the behaviours of various chemicals.
The following summer Parry pressed on to little avail and during the following winter of 1822–23 Fisher once more set up the portable observatory ashore and continued his experiments.