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from which the weight at any other barometrical height may 

 in the fame manner be deduced. Thus barometer 30 in tem- 

 perature 32^*, 1000 cubic inches of air weigh 329,855. grains; 

 then if the barometer be at 29,5, then 1000 cubic inches of air 

 will weigh by this rule 324,357 grains; for as 30. 29,5 :: 329,855. 

 324,357, but more exadly 324, 218; for fince a cubic foot of 

 air at barometer 29,5 weighs 560,249 grains; then as 1728. 

 560,249 :: loop. 324,218; the difference however is inconfide- 

 rable. 



To expedite calculations of the weight of air, I have formed the 

 annexed table of the weight of 1000 cubic inches of air (equal 

 13,888 fathoms or 83,333 feet,) at the following barometrical 

 heights. 



Weight 



