388 Mr. Harvey’s on the effects of the density of air 
atmosphere, always received increments to its rate ; and from 
its having lost through the whole of its experiments relating 
to the condensed air, the same inference may be deduced 
from it as from the preceding chronometer. The decrements 
in the above table, it will be remarked, are very nearly uni- 
form, from 30 inches to 48 inches ; but in the transition from 
48 inches to 54 inches, the change is considerable. It is also 
worthy of observation, that this time-keeper, when finally 
detached for twenty days, preserved a rate of nearly — i 5 ,, .o ; 
the dense air to which it had been so long exposed having 
materially augmented its losing rate, and apparently, com- 
municated to it a permanent character. 
The third set of experiments was with the pocket chrono- 
meters B and C, employed in the inquiries with the air pump, 
and the results of which are entered in the succeeding table. 
Experiments with the Pocket Chronometers 
B, C. 
Mean 
Temp. 
Mean 
Pressure. 
Number 
of days. 
Mean daily 
rate of B. 
Mean daily 
rate of C. 
O 
47 
30 in. 
6 
+ 4-3 
// 
+ 1.2 
47 
45 in. 
5 
=—5.2 
“4.4 
46 
60 in. 
5 
— 9.7 
— 8.2 
45 
75 in. 
5 
— 17.2 
— 9-5 
4 b 
30 in. 
5 
+ 4-5 
+ 0.6 
The rates recorded in the above table, it will be perceived, 
