70 Lieutenant Foster’s account , &c. 
By this experiment, it appears that the final number of 
vibrations which would have been made by the pendulum at 
Greenwich in 24 mean solar hours at the level of the sea, in 
vacuo, and at the temperature of 50° of Fahrenheit, by the 
method of disapp. of the white disk is - 86159,487 
and by the mean of its disapp. and re-app. 86159,621 
But from the final results deduced from the experiment 
made at Greenwich in April 1824, previous to leaving 
England, the total number of vibrations which would have 
been made by the same pendulum under the above circum- 
stances, by the 
method of disappearance, was - 86159,250 
and by the mean of disapp. and re-app. - 86159,380 
Having already stated, what I have considered to be the 
cause of the difference in the number of vibrations of the 
pendulum in these experiments ; the following arithmetical 
means of the results of the series in April 1824, and Novem- 
ber 1825, are to be considered as the proper number of 
vibrations of the pendulum, at Greenwich, to be compared 
with those obtained at Port Bowen, and are by the method of 
disappearance of the white disk - 86159,368 
and by the mean of its disapp. and re-app. 86159,500. 
