r 



347 



1 



J 



IdoCely, for it is ftated to be from 14 to 15 or 1 6 degrees of Reaa- 

 iQur. See Hygrometer: p. 104 and 284.. 



Saussure has given us a table, by the help of which the ab? 

 folute quantity of vapour at any barometrical height, in a cubic 

 foot of air being known, the proportion and abfolute quantity in 

 a cubic foot, at another barometrical height 3,6 inches lower, may 

 be known from the mercurial height 28,77 ^'^ ^'^^ °^ three inches 

 and one-half, nearly. 



This table I here give, adapting it to our meafures. 



Thus fuppofing the abfolute quantity of 

 diffolved vapour at any temperature, and 

 barometer 28,77 to be 10 grains per cubic 

 foot, then the quantity of vapour at a 

 height at which a barometer would ftand 

 at 25,17 inches would be 10 x 0,9528 = 9,528 

 and at the height at which a barometer 

 would ftand at feven inches, the quantity in 

 a cubic foot would be only 10 x 56230 = 6,23. 

 But ftill it is fuppofed that at ihofe great 

 heights, at which barometers would ftand fo 



lo.w, that the air is of the fame temperature as the original expe- 

 riment 



