Tempeeatuke of Evaporation. 



411 



TABLE VII. — Daily, Weekly, and Monthly Means of the Temperature of Evaporation, as deduced 

 from the Readings of the Wet Bulb Thermometer, in 1844. 



Annual Variation of the Temperature of Evaporation. — This follows the same law as the temperature of • 

 the air. The maximum occurs in July and the minimum in December and February. The means for the 

 thermal seasons are as follow : — 



Winter, Dec, Jan., Feb., 32°-54 Summer, June, July, Aug., 51°-48 



Spring, March, April, May, 41°-37 Autumn, Sept., Oct", Nov., 44°-72 



The mean temperature of evaporation for 1844 = 42°'55 



Diurnal Variation of the Temperature of Evaporation. — This, on the whole, also follows the same law as the 

 temperature of the air. The hours of maximum and minimum for the astronomical seasons and for the year. 



The epochs for the year for the temperature of the air and of evaporation are the same, and they are nearly 

 the same for the quarters. The secondary maximum in winter at midnight is also shewn in the means for the 

 tempei'ature of evaporation. 



The mean temperature of evaporation for the year occurs at 8* 19™ a.m. 

 T*" 32>n P.M. 



The interval between the two periods of mean temperature is ll*" 13" 



