on the rate of chronometers. 38 5 
Experiment for the summit of Chimborazo, elevated 
3573 fathoms above the level of the Sea. 
Place. 
Mean Temp, 
during the 
Experiment. 
Mean 
Pressure. 
Number 
of days. 
Daily rate 
of A. 
Daily rate 
of C. 
Daily rate 
ofF. 
Daily rate 
of H. 
Level of the Sea 
5 2 ° 
30 in. 
4 
— 1".9 
+ 2 ". 6 
+ z'.o 
+ 7"-9 
Summit of 
Chimborazo 
51 ° 
15 in. 
4 
+ 4 "- 2 
+ 9"-6 
-It - 
— ‘ 3 *3 
+ l/'-O 
Three of the chronometers used in the last experiment, 
viz. A, F, and H, were the same as those employed in the 
experiments for Geneva and Madrid ; and from which it 
will be perceived, that even under the influence of a much 
less pressure, the alterations of rate partook of the same 
character ; in one instance (F) losing from diminished pressure, 
and in the other cases (A, H,) gaining. The changes in the 
last experiment are more considerable, in consequence of the 
greater rarity of the air. 
As a final experiment on this part of the subject, the two 
excellent pocket chronometers (C, H,) employed in the last 
experiment, were placed beneath the receiver, and the air- 
exhausted until the mercurial guage sunk to 12.95 inches, 
being the elevation of the barometric column observed by 
Gay Lussac in his magnificent aerostatic ascent. The con- 
sequent alterations of rate were respectively -|- 13". 2, and 
+ i9".s. 
From the preceding experiments it may therefore be 
inferred, that a chronometer constructed in air, correspond- 
ing in density to its mean state at the level of the ocean, will 
undergo alterations of rate, when removed into a region 
MDCCCXXIV. 3 D 
