in the length of the pendulum vibrating seconds. 377 
level of the sea, the correction for which is 3,04 x -fo — 2,13. 
These corrections being applied, we have 86065,05 for the 
number of vibrations which would be made by the pendulum 
in a mean solar day in vacuo and at the level of the sea. 
On leaving Arbury Hill, I hastened to Dunnose in the Isle 
of Wight, anxious to complete my experiments before the 
winter; but on arriving there, I found the weather so bad, 
that after a short stay I was reluctantly obliged to postpone 
my observations at that station until the following spring. 
Operations at London. 
Before I left London in June, I took four series of vibrations 
of the pendulum at a high temperature, at Mr. Browne’s house 
in Portland Place ; chiefly with a view to afford me the means 
of checking my expansion of the pendulum by a comparison with 
other series of vibrations, which I purposed to observe at a low 
temperature on my return, and also to enable me to form some 
idea of the acceleration, when I should arrive at Unst. For 
the rate of the clock I am indebted to the observations of Mr. 
Browne. The results are contained in the following Table. 
Vibrations of the Pendulum at London. — ist Series. 
Date, 
1818 . 
Barometer. 
Thermom. 
Vibrations 
in 24 hours. 
Correction 
for 
Temp. 
Correct Vibrations 
in a mean solar 
day at 62 degrees. 
June 
1 3 
29,90 
O 
71,6 
86051,32 
4,06 
86055,38 
*4 
30,00 
70,1 
8605 1 ,90 
3>43 
86055,33 
l 5 
30,05 
69,9 
86051,99 
3>34 
86055,33 
16 
2 9>95 
7°>5 
8605 1,82 
3,60 
86055,42 
Mean 
29,98 
70,5 
86055,36 
The barometer being at 29,98 inches, and the thermometer 
mdcccxix. 3 D 
