162 On tlte Influence of the Humidity of the Atmosphere 
theory, but still more because his extreme accuracy as an ob- 
server, joined to his profound knowledge of this department of 
physical science, gives them an authority which can be claimed 
for the. materials of few meteorological journals. 
Mean Tempe- 
rature of the 
Air. 
Degrees of Les- 
lie’s Hygrome- 
ter. 
Grains of Mois- 1 
1 ture in 100 Cu- 
bic Inches of 
Air. 
Point of Depo- 
sition by For- 
mula. 
Mean Mini- I 
mum Tempe- | 
rature. 
Difference of 
Point of Depo- 
sition, and Mi- 
j nimum Temp. 
January, 
O 
33 
O 
4,9 
.1238 
29.1 
28.5 
-f 0.6 
February, 
42 
8.1 
.1612 
36.8 
35.7 
-j- 1.1 
.March, 
43 
14.7 
.1451 
33.8 
34.9 
+ 1.1 
April, 
47 
23.1 
.1458 
33.9 
36.9 
-i- 3.0 
May, 
54 
23 
.2050 
44.3 
45.5 
— 1.2 
June, 
59 
29.7 
,2304 
47.9 
48.9 
— 1.0 
July, 
61 
32 
.2444 
49,7 
50.3 
— 0.6 
August, 
60 
27.7 
.2463 
49.9 
50.9 
— 1.0 
September, 
55 
20.3 
.2214 
46.7 
46.9 
— .2 
October, 
4 9 
12.2 
.1967 
42.9 
42.6 
+ -3 
November, 
38 
7.8 
.1396 
32.6 
31.4 
4 1.2 
December, 
33 
6.5 
.1177 
27.9 
27.8 
+ 0.1 
48 
.1814 
39.6 
40.0 
The absolute humidity of the atmosphere, exhibited in the 
column entitled Grains of Moisture in 100 cubic inches of air, 
was computed by a formula which I have given in the article 
Hygrometry already alluded to, and the correctness of which 
I have since verified by a careful comparison of the results it 
affords, with the quantity of moisture in the air, as determined 
by direct experiment. The column shewing the mean point of 
deposition for each month, exhibits the temperature at which 
the air, at the time of observation, if cooled down to that point, 
would begin to deposite the vapour in admixture with it. The 
adjoining column contains the mean minimum temperature as 
given by a self-registering thermometer ; and the last column 
shews the difference between the lowest temperature and the 
point of deposition.. The coincidence is sufficiently great to 
establish the important fact, that the quantity of moisture dis- 
solved in the atmosphere is so intimately connected with its mi- 
nimum temperature, that the former may be readily inferred 
from the latter. It was not difficult, indeed, to arrive at the 
conclusion, that, as the quantity of moisture which can exist in 
