656 Mb W. HOPKINS, ON THE EXTERNAL TEMPERATURE OF THE EARTH, 



Hence we deduce as before the following corrected results : 



s a - s, = 6°,5 

 s -s 2 =ll°,4 

 s - « 3 = MM 



s - S 4 = 22°,4. 



Therefore 



H — H t 



These results are free from the anomaly presented by those previously obtained. Taking 

 the mean of them, we may assume generally, where s and H correspond to any assigned 

 latitude, that 



8 - 8 



or s -s = ,93 (H - H). 

 We may also take the condition that s and H would vanish together, which gives 



«o ■ >93H , 

 and therefore 



s = ,93/7, 



= ,93 h Q, 

 as the general relation between s and H. 



24. The whole effect, it will be recollected, of the solar heat on the mean annual tem- 

 perature of the Earth's surface in any proposed latitude consists of the direct effect (AQ) of 

 solar heat radiating upon the Earth, and the indirect effect (s) of that heat arising from the 

 consequent elevation of the temperature of the atmosphere. The above result shews that the 

 latter of these is very nearly equal to the former, or rather that it would be so if there were 

 no causes for a lateral transference of heat perpendicular to the parallels of latitude, and no 

 local causes of disturbance of mean annual temperature. We may assert, therefore, in general 

 terms, that the mean annual temperature of the surface of the Earth at any point is higher by 

 nearly 2hQ than it would be if the solar heat did not exist. And the same proposition may 

 be enunciated equally with reference to the lower stratum of the atmosphere, which, as already 

 stated, may be considered to have the same mean temperature as the surface of the Earth 

 itself 



