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degrees higher thnn that at five feet above the furface of the 

 earth ; contrary to the grounds of calculation. Nor is the hotteft 

 hour of the day the fitteft time, fince the heat is above all pro- 

 portion fome degrees greater than at the height of 75 feet. The 

 propereft times are therefore the mean hours between fun-rife 

 and the hotteft hour of the day*, and between this and fun-fet. 

 EJfais des Phj's. §131, &c. 



However, fuch confiderable difparities occur only in calm, 

 clear and ferene weather; on cloudy days, when the fun does not. 

 appear, they vanifh. Ibid. § 135. 



Whenever a fog or mift appears in any ftratum of air, it com- 

 municates about a degree, or half a degree, of heat to the ftratum 

 in which it is found. Ibid. § 142. A circuraftance that deferves 

 notice in eftimating the mean temperature of the atmofphere.. 

 Mr. James Six, of Canterbury, made a number of obfervations on 

 the temperatures fix or nine feet above the earth ; and alfo on 

 that which prevailed 220 feet above it; and his refults were in 

 general analogous to thofe previoufly obtained by Pidet. But the 

 temperatures of whole days, or of days and nights only, were 

 noticed, and not the fimultaneous differences at different heights; 



befides 



* This I have added. 



1 



