478 



In the tabular view which is given in page 469 of the 

 differences between the observed and computed rates, 

 Trinidad, Ascension, and Maranham are three stations 

 at which, in my experiments, the discrepancies were 

 most considerable in amount: 



At Trinidad the observed vibrations were in defect 3-97 

 At Ascension in excess 5'18 



At Maranham in defect 4-23 



Sum - - 13-38 



For this reason it appeared to the committee of the 

 Royal Society, by whom suggestions were made for 

 Captain Foster's voyage, very desirable that the ex- 

 periments should be repeated at those stations. This 

 was accordingly done, and the results of the repetition 

 are stated in Mr. Baily's report in the table, p. 88. The 

 comparative results are as follows : The pendulum, 

 which vibrated seconds in London, made at Trinidad 

 86267-27 vibrations according to Sabine, and 86267-24 

 according to Foster; at Ascension, 86273-04 Sabine, 

 and 86272-25 Foster; at Maranham, 86259-77 Sabine, 

 and 86258-74 Foster. At Trinidad and Maranham the 

 places of observation were identical ; at Ascension there 

 was a slight difference, Captain Foster's pendulums 

 were vibrated in a house in the Barrack Square, mine in 

 a storehouse, within, I believe, a quarter of a mile's 



netical meridians might influence its time of vibration. Experiment, 

 however, had already decided this question. At Sierra Leone, the 

 first station which I visited, the pendulums were successively 

 vibrated in planes at right angles with each other, with results so 

 nearly accordant as to be in effect identical. (Pend. Expts., pp. 

 15-16.) 



