4 BappicKER—On the Influence of Magnetism on the Rate of a Chronometer. 
The same circumstances occurred when the chronometers were landed upon a 
small island in Fair Haven, on the north coast of Spitzbergen, but Fisher finds it 
‘‘ needless to detail them.” 
On page 200 a Table is given containing the sea-rates of the nine chronometers, 
deduced by dividing the difference between the chronometer errors in London 
and Spitzbergen by the interval in days between them, and the probable approxi- 
mate land-rates, obtained by taking the mean of the rates taken on shore before 
leaving England and those observed at Spitzbergen. ‘‘ And although a mean 
between the rates of chronometers obtained at different times may not accurately 
be the mean rate they would have had during the interval of those times, from the 
continued variation to which they are subject,” yet a comparison of these rates 
shows that the daily rates of all the chronometers had been accelerated on board 
ship by, respectively— 
Ae 87, Saeed 8s 4196 54 0848, 4 643s F085 47535. 
‘This acceleration is not peculiar to high latitudes; it was observed very soon 
after the chronometers were put on board in the river.” 
Fisher adds some more instances, which it will hardly be necessary to repro- 
duce. Especially the cases of acceleration in Harrison’s time-keeper, in 1764, and 
a watch of Kendal, on Cooke’s voyage towards the South Pole, in 1772-3-4, do 
not prove much, since it is well known that acceleration is peculiar to new 
chronometers, where (even in first-rate instruments) it not seldom lasts some years 
before it ceases, and that inferior chronometers show frequently a tendency to 
gain continually. ; 
Fisher, on trying to explain the above changes of rates, adds that they cannot 
be attributed to the motion of the vessels, as the acceleration was observed when 
the ships were firmly beset with ice, or riding at anchor, without any perceptible 
motion ; and that the temperature cannot be the cause either, since a two-hourly 
account of it, kept on board and on shore, did not show the least correspondence 
between the change of rates and the temperature at the time. He then proceeds 
to poit out the ship’s magnetism as the source from which the acceleration arose, 
which he makes probable by her action on a compass. The reason why I have 
given Fisher’s observations so fully lies in their remarkable results, which will 
be referred to below, as also in their having called forward the criticism of 
Peter Barlow, which is now to be shortly reproduced. 
In his first Paper (No. 6) he is surprised at the considerable amount of the 
changes of rate in the chronometers, as well as at their lying all in the same 
direction—acceleration on board ship. He is unable to find any sufficient reason 
why the ship’s action should not be retarding as well, and remarks ‘that we are 
led strongly to suspect that the remarkable change in the rates of the nine 
chronometers of the ‘ Dorothea’ and ‘ Trent,’ reported by Mr. Fisher, must have 
