on the rates of chronometers. 
379 
Experiments with Pocket Chrono- 
meters C, D. 
Mean 
Temp. 
Pressure. 
Number 
of Days. 
Mean daily 
rate of C. 
Mean daily 
rate ofD. 
0 
46 
Detaebed 
29.1 in. 
4 
'/ 
+ 2.5 
+ 4.0 
46 
27 
4 
+ 3 -° 
+ 5-2 
47 
25 
4 
+ 3-4 
+ 6.1 
46 
23 
4 
+ 4-7 
+ 7-2 
45 
21 
3 
+ 6.4 
+ 9-4 
42 
19 
4 
+ 7-6 
+ 1 1-3 
43 
17 
3 
+ 10.5 
+ i 3-4 
44 
>5 
4 
+ 11 -7 
+ 144 
45 
*3 
4 
+ 13-4 
+ 15-8 
49 
11 
4 
+ I 4 -S 
+ 171 
48 
9 
4 
-£• 16.0 
-£* 18.2 I 
48 
7 
3 
+ 19.0 
+ 20.4 
50 
5 
4 
+ 18.6 
+ 22. 1 
49 
3 
4 
+ 19-9 
The next set of experiments was performed with the eight 
day chronometer E, possessing the very excellent detached 
rate recorded in the first of the following columns. In the 
second column of the same table is also entered the daily 
rate of the same chronometer when placed in air, diminished 
in density in the ratio of 60 to i ; and in the third column 
is its rate, when afterwards restored to the full pressure of 
the atmosphere. The mean temperature of the first period 
was 56 0 , of the second 58 0 , and of the third 57 0 . 
