430 PHILOSOPHY OF STORMS. 



by radiation. If it stays where it is, it would prevent the 

 condensation of vapor altogether; and if it is radiated off 

 into space as fast as it is evolved, it is not there to do the 

 work assigned to it by me. In fact, that my proposition is 

 absurd and impossible ; that I speak of a great cold to con- 

 dense the vapor, and a great heat to expand the air in the 

 cloud so much as to make it greatly lighter than air sur- 

 rounding the cloud at the same height." To avoid this di- 

 lemma, the Professor says " the caloric evolved during the 

 formation of cloud is actually radiated off into space ; at 

 least, so much of it as to prevent the cloud from being 

 warmer than the surrounding air at the same elevation. " 



The answer to this objection is very easy. First, it is 

 known from the dew point, that if air is cooled down by 

 expansion from diminished pressure 30 below the point of 

 condensation, a large portion of its vapor will be condensed 

 into cloud. Now, if air goes up in a column six thousand 

 yards high, it will expand, by diminished pressure, suffi- 

 cient to produce 30 of cold, even if it should receive latent 

 caloric enough to heat it 30, for without this latent caloric, 

 it would be more than sixty degrees colder on reaching that 

 height; so it is not necessary to the formation of cloud of 

 great density that any of the 'caloric evolved should escape 

 into space by radiation during its formation. 



This will not be denied by any one who understands my 

 theory well enough to repeat the numbers just mentioned. 

 He will perceive that the air, in going up six thousand 

 yards, has been subjected to a cooling process, which would 

 have reduced its temperature more than 60, if no latent ca- 

 loric had been given out ; but, in consequence of the latent ca- 

 loric evolved, it will be cooled only about half that quantity, 

 and of course will then be about 30 warmer than the air 

 surrounding the cloud at the same height; consequently 

 it will be about ^ lighter. 



Besides, what right has the Professor to take it for granted 



