SHORT MEMOIRS ON METEOROLOGICAL SUBJECTS. Jhd 



One can persuade himself of tbe correctness of this conclusion by the 

 following computation. The weight (in kilograms) of the aqueous vapor 

 having a tension j) (in millimeters) in one cubic meter is found by the 

 well-known formula 



^P.o So P 0001058 



where So is the specific gravity of air at temperature 0° 0. Hence tbe 

 weight of aqueous vapor contained in a stratum of air of differential 

 thickness dh and horizontal area unity is 



^ 0.0010582 .jETi.j 



The integration of this equation gives a formula for the total weight 

 of the aqueous v apor contained in the atmosphere up to any definite 

 height. The temperature t is, strictly speaking, also dependent on the 

 altitude ; but we will, in accordance with all experience, put 



_ ^0+ ^n _ ., 

 I — ^ — t , 



and thus find 



^^ 0.0010582 ^, /_ ^.m:i\ 

 ^= 1 + at' i^o C log e (^1-10 J, 



or 



^ 0.0010582 oQQn/i 1^^^^ 



^ = ' l + aV P" ^ ^^^^ (^1-10 J 



For large values of Ji, therefore, by extending the integral to the 

 limits of the atmosphere, the negative member of this expression dis- 

 appears, and it is now quite clear that the actual weight of the aqueous 

 vapor in the atmosphere is to that resulting from Dalton's hypothesis 

 as 2830 to 12829, or as 0.22 to 1. 



For example, the mean vapor-tension at Vienna in July is 11 milli- 

 meters, the temperature 20o.3 C. ; at the altitude of 8,000 meters, the 

 probable temperature is about — 19o.7 C. ; the mean temperature of the 

 whole atmosphere of aqueous vapor is therefore nearly 0° C. The 

 formula gives the total weight of aqueous vapor = 33 kilograms, corre- 

 sponding to a pressure of yoY32 — 0.0032 atmosphere, or a mercurial 

 column of 2.4 millimeters. If, therefore, the aqueous vapor contained 

 in July in the atmosphere above Vienna could expand according to 

 Dalton's law, the vapor-tension at the earth's surface would sink from 

 11 millimeters to 2.4 millimeters. 



[Note. — The following equation resulting by integration from our 

 previously given formula of interpolation : 



1 058*^ 

 Q = (]V^) ^I'l'o (1 - 0.123 Ji + 0.00523 ¥), 



where the unit of ^ is a thousand meters, gives Q = 32.6 kilograms, or 

 2.3 millimeters on the mercurial barometer, for h = 8,000 meters.] 



