FAILURE OF CLIMATIC THEORIES. 9 



theory* According to that eminent geologist, the 

 temperature of the Arctic regions would be raised by 

 the removal of the continents from polar and temperate 

 regions to a position along the equator. But if the 

 equatorial regions were occupied by land instead of 

 water, the possibility of conveying heat to temperate 

 and Arctic regions by means of ocean currents would 

 be completely cut off. In fact, one of the most effectual 

 ways of lowering the mean temperature of the globe 

 would be to group the continents along the equator. 



The surface of the ground at the equator becomes 

 intensely heated by the solar rays, and this heat is 

 radiated into space much more rapidly than it would be 

 from a surface of water warmed under the same con- 

 ditions. Again, the air in contact with the hot ground 

 becomes more speedily heated than it would if it were 

 in contact with water, and consequently the ascending- 

 current of air over the equatorial lands carries off a 

 greater amount of heat than it could take away from a 

 water-surface. Now, were the heat thus carried off to 

 be transferred by means of the upper currents to high 

 latitudes, and there employed in heating the earth, 

 then it might to a considerable degree compensate for 

 the absence of warm ocean currents. In such a case 

 land at the equator might be nearly as well adapted 

 as water for raising the temperature of the whole 

 earth. We know very well, however, that the heat 

 carried up by the ascending current at the equator 

 performs little work of this kind, but on the con- 

 trary is almost wholly dissipated into the cold stellar 

 space above. Thus, instead of warming the globe, this 

 ascending current is in reality a most effectual means 

 of getting rid of the heat received from the sun, and 



* For a fuller statement of Sir Wm. Thomson's views, see chapter 

 on the Cause of Mild Polar Climates. 



