311 
experiments made with an invariable pendulum , &c. 
From the preceding observations we have the following 
results. 
Vibrations of the Pendulum at London. 
Date. 
Barom. 
Therm. 
Vibrations in 
24 hours. 
Corr. for 
Temp. 
Vibrations in 
24 hours, at 
60 degrees. 
Inches. 
O 
April 18 
29,70 
57,5 
86084,56 
— 1,06 
86083,50 
19 
29,60 
57,3 
86084,58 
— 1,14 
86083,44 
20 
29,58 
58,4 
86084,39 
— 0,68 
86083,71 
21 
29,80 
59,7 
86083,89 
— 0,13 
86083,76 
22 
29,98 
59,1 
86084,63 
— 0,38 
86084,25 
23 
29,53 
60,8 
86083,33 
+ 0,34 
86083,67 
29,70 
58,8 
86083,72 
The mean height of the barometer being 29,70 inches, and 
that of the thermometer 58°, 80, if the specific gravity of the 
pendulum be taken at 8, the correction for the buoyancy of 
the atmosphere will be 6,45. Adding this to the mean num- 
ber of vibrations before found, we obtain 86090,17 for the 
number of vibrations which would be made in a mean solar 
day at the temperature of 6o°, and in a vacuum. The cor- 
rections applied for temperature are calculated on the suppo- 
sition of the expansion of this pendulum being the same as 
that of the one before alluded to, which, as both are con- 
structed of plate brass, will probably not occasion any sen- 
sible error. 
On the completion of the preceding observations, the 
following were made by Sir Thomas Brisbane, and Mr. 
Rumker. 
