382 Mr. Harvey on the effects of the density of air 
These results having been produced by air corresponding 
in density to its mean state at 201 fathoms above the level 
of the sea, another set of experiments was instituted on the 
supposition that a chronometer was removed from the shores 
of the Mediterranean to the lofty plains of La Mancha and 
the Castiles, where the mean barometric pressure is denoted 
by 27.81 inches. The following table contains the results : 
Experiment for Madrid, elevated 329 fathoms above 
the level of the Sea. 
Place. 
Mean Temp. 
during the 
Experiment. 
Mean 
Pressure. 
Number of 
Days. 
Mean daily 
rate of A. 
Mean daily 
rate of F. 
Mean daily 
rate of H. 
Mean daily 
rate of I. 
London 
0 
s* 
detached 
Z9.86 in. 
4 
// 
— 4-5 
'/ 
+ 3-* 
+ 7-4 
'/ 
— *7-4 
Madrid 
S3 
27.81 
5 
- 2.4 
-i- 0.8 
+ 9- 6 
— 13.1 
Three of the chronometers employed in the two preceding 
sets of experiments, viz.. A, F, H, were the same, and which 
therefore enables us to perceive, that a difference of -^ths of 
an inch in the barometric column produces an alteration of 
rate. The changes also are more considerable in proportion 
as the difference in the altitudes of the mercurial column is 
increased, as is proved in the succeeding table. 
Difference in the 
Altitudes of 
the Mercurial 
Columns. 
Increment 
communicated 
to the 
Chronometer A. 
Increment 
communicated 
to the 
Chronometer H. 
Decrement 
communicated 
to the 
Chronometer F. 
1.26 in. 
+ o''.6 
-{- l".8 
~ l'-5 
.205 in. 
-f- 2". 1 
-f 2. "2 
— 2 ". 3 
