acceleration of the pendulum in different latitudes. 165 
oil had undergone this process in the year 1803, and had 
been laid by since that time. 
The experiments, of which the account is now pre- 
sented to the Society, were made in the course of two voy- 
ages of discovery in search of a North-west passage ; one 
in the summer of 1818, and the second in the years 1819 and 
1820. 
In the first of these voyages, the clock and pendulum 
marked No. 2, were alone employed. No. 1, being sent at 
the same time to Spitzbergen with Mr. G. Fisher ; but both 
the clocks being disposable when the second expedition was 
fitted out, they were both embarked, with a view of obtain- 
ing double and corresponding results. 
It is designed to detail, in succession, the proceedings at 
each station, where an opportunity was afforded of landing and 
setting up the clocks ; and to conclude, by recapitulating the 
number of vibrations made by each pendulum in the diffe- 
rent latitudes in which it was tried ; and by stating the de- 
ductions regarding the figure of the earth, which follow 
from the accelerations which were thus determined. 
FIRST VOYAGE. 
Island of Brassa, Shetland. 
The ships having anchored in Brassa Sound on the 30th of 
April 1818, for the purpose of procuring a supply of fresh 
provision, and their stay, although designed to be very short, 
being understood to depend in some measure on the wind, 
the clock was landed, and, by the kindness of William 
Mouatt, Esq. was set up in a lower room at Gardie House, 
