584 On Evaporation. 
with the same evaporating force, a strong wind 
will double the effect produced in a still atmos- 
phere. Thus, if the aqueous atmosphere be 
correspondent to 40° of temperature and the 
air be 60°, the evaporation is the same as if the 
aqueous atmosphere were at 60° of temperature 
and the air 72°; and in a calm air the evapora- 
tion froma vessel of 6 inches in diameter in 
such circumstances would be about .g of a grain 
per minute, and about 1. 8 grains per minute 
in avery strong wind ; the different intermediate 
quantities being regulated solely by the force of 
the wind. 
The following table exhibits the ratios and 
quantity of water evaporated in each temper- 
ature, derived from’ the preceding theory, and 
confirmed by experiments, as far as they have 
been extended. The first column expresses the 
temperature; the second, the corresponding 
force of vapour taken from the preceding table; 
the other three columns give the number of grains 
of water that would be evaporated from a surface 
of 6 inches in diameter in the respective tem- 
peratures, on the supposition of there being 
previously no aqueous vapour in the atmos- 
phere. These columns present the extremes and 
the mean of evaporation, likely to be noticed, 
or nearly such: for, the first is calculated upon 
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