THEORY DEDUCED FROM PHYSICAL LAWS. 5 



up the air 42, which being added to 48 makes up the 90 

 which it would have fallen if there had been no latent 

 caloric in the vapor condensed. 



But as the atmosphere on the outside of the ascending 

 column is 60 colder at the elevation of sixty hundred yards, 

 and within the column only 48 colder, the specific gravity 

 of the cloud will be at least V less than the outer air at the 

 same elevation, even without allowing anything for the 140 

 of latent caloric given out by the congelation of the water. 

 In this calculation, no allowance is made for the greater 

 specific heat of rarefied air, but this will be fully compen- 

 sated by the 140 given out by the congelation of the water, 

 and by the higher dew point in the column than in the sur- 

 rounding air. 



13. If it had been assumed that air, in ascending, falls 

 only one degree for a hundred yards, then, according to the 

 same mode of calculation, it will be found that by falling 

 36, making allowance for the greater space now occupied 

 by the air, sufficient vapor would be condensed to raise the 

 temperature of the air 24, and then, 24 added to the 36, 

 will make up 60, which would have been the actual de- 

 pression of temperature in ascending sixty hundred yards, 

 if the vapor had contained no latent caloric. 



It is not at all probable that the actual depression of 

 temperature of air on being rarefied by diminished pressure, 

 would be greater than one degree and a half for every hun- 

 dred yards of ascent ; but even if it should be two degrees, 

 it will be found that the latent caloric evolved when the 

 dew point is high, would prevent it from falling one degree 

 for every hundred yards of perpendicular ascent, and there- 

 fore, even in this case, its specific gravity would be con- 

 stantly less than that of the atmosphere at its own elevation. 



14. If we suppose a very narrow column of air to begin 

 to rise, as mentioned in article 12, and a cloud to be formed 

 in it reaching to a height where the barometer would stand 



