446 PHILOSOPHY OF STORMS. 



Let us suppose then, that one half of the atmosphere at 

 80 Fahr., should be mingled with the other half at zero, 

 over the region round Wilmington, and that 5.1 inches of 

 rain is the result. What will be the temperature of the 

 mingled mass after the rain? The mean temperature is 

 40, which would be the temperature after the mixture, if 

 no latent caloric is given out in the condensation of vapor. 

 But from the principles explained before, it will be found 

 that as five inches of rain is ^ of the whole atmosphere in 

 weight, the latent caloric given out in the condensation of 

 the vapor forming this rain, will be sufficient to heat the 

 whole compound 59.7, which being added to the mean 

 temperature 40, will make the temperature of the air after 

 the rain 99.7, almost 20 hotter than the hottest half of the 

 atmosphere before the mixture. 



This result, however unexpected, ought not to appear sur- 

 prising. For if gentlemen will frame theories on loose prin- 

 ciples, without once putting these principles to the test of 

 calculation, and without even taking the least notice of the 

 latent heat of vapor, or the specific heat of air, they ought 

 not to be surprised that a little plain arithmetic should dis- 

 sipate their empty visions, and "leave not a wreck behind." 



Theorists will pardon me for this sweeping denunciation, 

 when I now voluntarily come forward and plead guilty to 

 the same charge; for I too framed an hypothesis to account 

 for rain, and advanced it under the high sounding name of 

 theory. 



Having found that the Huttonian theory would not bear 

 the test of calculation, I imagined there was but one other 

 possible mode of condensing vapor, and that was, that the 

 vapor, by its own elasticity in the lower parts of the atmos- 

 phere, thrust itself up into a cold stratum above, whenever 

 such a one overlapped the one below, and was thus con- 

 densed into rain. 



This hypothesis I thought was altogether reasonable, from 



