experiments made with an invariable pendulum. 21 
Results. 
1824. 
Correct Number of Vibrations 
made by the Pendulum in 
a mean solar day, by 
Disappearance. 
Mean of Disap. 
and Re-ap. 
From 20th April P. M. to 21st A. M. 
86152,44 
86152,57 
22(1 
86152,71 
86152,82 
23d 
86152,67 
86152,78 
24th 
86152,72 
86152,85 
25th 
86152,70 
86152,83 
— - 2 1 st — P. M. to 22d A. M. 
86152,87 
86152,97 
23d 
86152,75 
86152,85 
24th 
86152,79 
86152,91 
25th 
86152,77 
86152,90 
— 2 2d — P. M. to 23d A. M. 
861 52,63 
86152,74 
24th 
861 52,75 
86152,89 
25 th 
86152,79 
86152,92 
— 23d — P. M. to 24th A. M. 
86152,87 
86153,03 
25th 
86152,83 
86152,98 
— 24th — P. M. to 25th A. M. 
86152,81 
86152,95 
Mean 
86152,74 
86152,87 
Barom. 29,82, Ther. 56,0°, Buoyancy 
=2 -f 6,06 
+ 6,06 
Elevation 181,5 feet. Correction i 
= °’75 X 1 <7 • • • $ 
= + 0,45 
+ <M 5 
No. of vibra. at Greenwich in vacuo at} 
the level of the sea, temp. 50° of Fah. \ ^ 9 » 5 
86159,38 
The above correction for buoyancy of the atmosphere, 
has been deduced from the mean height of the barometer 
29,82, and temperature 56°, o, together with the specific 
gravity of the pendulum supposed to be 8,61 . That for eleva- 
tion, by the duplicate ratio of distances from the earth’s centre 
(3954,583 miles) the ball of the pendulum at Greenwich 
being 18 l~ feet above the level of the sea. This was deduced 
from the Account of the Trigonometrical Survey of Great 
