156 LIFE ON THE EARTH. 



distribution of water wanned between the tropics, 

 we must conclude that no material elevation of mean 

 temperature can be effected by means of oceanic 

 currents, beyond that imparted by the gulf-stream 

 and winds which blow in the same direction. 



What appears to be the most favourable distribu- 

 tion of land and water for the diffusion of heat, is 

 neither an equatorial nor a polar position of large 

 continents; nor indeed of large continents at all, 

 but low islands scattered over the area of the globe, 

 amidst large breadths of water 1 . By this means 

 the watery communications being everywhere easy, 

 the whole ocean would acquire the greatest uni- 

 formity of which it is capable, the lands would par- 

 take in this equality, and the general temperature 

 would be something exalted by the absence of the 

 cooling effect on the atmosphere of the lofty moun- 

 tain-ridges, for these intercept and mix the aerial 

 currents, and chill the winds which cross their 

 snowy tops and afterwards traverse the lower 

 ground. The thermometric range of mean temper- 

 ature on the surface of the earth (the Pole not being 

 in the coldest zone) is about 100 Fahr.; that of the 

 sea, where most warmed by the Atlantic currents, 

 even to the Pole, probably not above 80 Fahr. 



1 Prof. Hennessy has suggested a similar view of the subject. 

 Atlantis, Jan. 1859. 



