PHILOSOPHY OF STORMS. 



SECTION FIRST. 



THEORY DEDUCED FROM PHYSICAL LAWS. 



1. THE experiments of the illustrious Dalton and Gay- 

 Lussac have shown that when the dew point is 80 Fahren- 

 heit, and the barometer 30 inches, the quantity of vapor in 

 atmospheric air is one forty-eighth of the whole weight and 

 one thirtieth of the whole bulk ; when the dew point is 71, 

 the quantity is one-fourth less; and when the dew point is 

 59, the quantity of vapor is only one half as much as when 

 it is 80 ; and at 39, the quantity would be reduced to one 

 quarter, &c. 



2. It is well known by observation that the temperature 

 of the atmosphere falls about one degree for every hundred 

 yards above the level of the ocean, in temperate latitudes, 

 at a mean, in the summer season, and a little less, perhaps, 

 in winter : and in the torrid zone at all seasons, it is pro- 

 bable this quantity is near the truth. This rule extends to 

 the height of seventy or eighty hundred yards at least. 



3. It is known by direct experiment and also indirectly 



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