on Evaporation. 423 
air, at about four o'clock in the afternoon : and the first ob- 
servation, made in that state, was thus : 
8,— P. M. 0,0 95,0 65,73 
The pump was then worked, for extracting a part of the 
air, and time given for the instruments to settle, and they 
were found, 
8,15*' ^,5 94,0 65,75 
After this observation, and after each of the following, the 
pump was worked, and time also given for the instruments 
to settle. 
8,3°' 
i3>° 
9i>° 
66,75 
8 >45 
86,5 
67 
£M5 
25.0 
86,0 
67.75 
9>3° 
29,3 
0,65 
67 
After this, the pump was no more worked the same day, 
but the two following observations were still made. 
10,0' 29,23 0,65 89,0 66,5 
11,0 29,23 0,65 95,0 64,5 
The apparatus was left in that situation till the next morn- 
ing, when the following observation was made before work- 
ing the pump. 
6,20' A. M. 29,35 0,55 97,5 63,15 
The pump was then worked, and the best possible vacuum 
was produced, in which, according to Mr. Nairne’s experi- 
ments, there could not be any sensible quantity of air. 
6,40' 29,40 0,50 96,5 63,15 
In comparing the results of this experiment with those of 
the first, moisture, as I have said, is generally greater in pro- 
portion to the temperature. But, setting this aside, and 
comparing the motions of the hygrometer and the thermo- 
3 1 2 
