ATMOSPHEROLOGY. — THEORY OF RAIN. 423 



27°, 2 lb. ; at temperature 54% 4 lb. ; at temperature 

 81°, 8 lb. and so on. As such, the numbers in the 

 second column of the above Table, show the quan- 

 tity of water in pounds which 365 lb. of air can 

 contain at any temperature between — 24° and 108°. 

 Suppose, then, for example, two masses of air of 

 365 lb. weight each, one of the temperature 18°, 

 the other 36°, a case quite within the limits of pro- 

 bability in the polar regions, to be mixed together, 

 the resulting temperature would be nearly the mean 

 of the two, or 27°. But the two masses of air be- 

 fore commixture, if saturated, must contain respec- 

 tively 1.58 lb. and 2.53 lb. of moisture, the sum of 

 which, 4.11, exceeds by 0.11 lb. or one-ninth of a 

 pound, the quantity of water, as shown by the 

 Table, which twice S65 lb. of air could possibly 

 sustain at the mean temperature of 27°. This 

 0.11 lb. of water must therefore be precipitated 

 after the commixture of every 730 lb. of saturated 

 air of the temperatures proposed. At higher tem- 

 peratures, however, the precipitation must be great- 

 er ; for, suppose the two assimilating streams of air 

 to be of the temperatures 42° and 84° ; then the 

 quantity of water suspended by 365 lb. of each, 

 would be respectively 2.95 and 8.64, amounting to 

 11.59 lb. ; but the quantity of moisture which 

 730 lb. of air could at most support, at the mean 

 temperature 63°, would be only 10.12 lb., so that 

 the excess 1.47 lb. must be precipitated. 



