Mr Troughton on the Length qfthe Pendulum, 75 
separately ; an important circumstance in analysing those bodies, 
the composition of which is multifarious and complicated. 
( To he continued.) 
Art. XII. — Comparison between the length of the Seconds 
Pendulum^ as detei'mined by Mr Whitehurst and Captain 
Kater. By Edward Troughton, Esq. E. R. S. 
Tn examining Mr Whitehurst’s experiments on the length of 
the Seconds Pendulum, Mr Troughton observed, that the re- 
sult admitted of various corrections, which were not applied by 
the gentleman who calculated the length of the pendulum from 
these experiments*. He therefore proceeded to compute the 
amount of those corrections, and obtained the following results. 
The length of the Seconds Pendulum, as calculated by Dr 
Rotheram, and examined and approved of by Dr Hutton, was 
39.11960 inches, when vibrating in a total arc of 6° 40', and 
in air at the temperature of 60°. 
Inches. 
Whitehurst’s length of the pendulum, 39.11960 
Correction for circular arcs, + 0.01654 
Correction for the weight of the wire rod, — 0.00080 
Correction for of temperature, in order to com- 
pare it with Captain Kater’s result, — 0.00052 
Correction for the buoyancy of the air, -f- 0.00404 
Correction for elevation above the sea, + 0.00030 
Sum of positive corrections, + 0.02088 
Sum of negative corrections, — 0.00132 
Difference to be added to the length of the pendu- 
lum, 4- 0.01956 
Whitehurst’s length of the pendulum, 39.11960 
Whitehurst’s length of the pendulum corrected, 39. 13916 
* The object of Mr Whitehurst was not to obtain the length of the simple pen- 
dulum ; but, from two pendulums of different lengths, to obtain a measure, in 
such a way, that every other person who used the same means could obtain the 
same measure, He had no occasion, therefore, to apply any corrections to his re.* 
suits. 
