332 Mr. G. H. Knibbs : Mathematical Analysis oj 



revised edition (1907) of the Smithsonian Meteorological 

 Tables. 



An example will illustrate : the degrees are centigrade; 

 assumed pressure 760 mm., 



T = 27-2; * = 16-7j T-* = 10*5. 



From Table 43 we have forT = 27°*2 C, 26*78 mm.; and for 

 ; = 16°-7 C, 14-12 mm. From Table 44, for T-* = 10°'5 C. 

 and pressure 760 mm., we have by interpolation between 10 

 and 11, 5*34 ; hence for the relative dryness we have 



i i f-1 i f 14-12 -5-34\ „ 70 ,.* 



In this way the quantities r\ shown in the tables of data 

 were calculated for the whole of the observations. 



It is no doubt desirable to base the formula for evaporation 

 from a body not on the relative but on the absolute capacity, ?, 

 for further absorption of aqueous vapour in the air. This 

 would be 



S = F v = Y-f+q, (6) 



and may be called the absolute dryness or saturation deficit. 

 The rate of such absorption would then be regarded as 

 depending on the temperature, as well as on the exhaustion 

 of this capacity for absorption. 



Three methods of taking account of the effect of dryness in 

 promoting diffusion suggest themselves, viz., making the rate 

 of evaporation a function of : — 



(a) The temperature and relative dryness ; or 



(b) The temperature and absolute dryness (or amount 



necessary to saturate the air at the temperature in 

 question); or 



(c) Temperature and the difference of reading between 



the two bulbs. 



We shall now consider the question of evaporation from a 

 liquid in a circular tank of small dimensions, and its appli- 

 cations to the matter in hand. The data, and calculations 

 based thereon, furnishing measurements of total loss from 

 the human body, are the following : — 



