LIFE ON THE EARTH. 153 



On the other hand, he supposes that if all the 

 land, similarly shaped, were collected along the 

 equator, while the poles were overflowed, the whole 

 earth would be warmer than it is now. This ap- 

 pears somewhat doubtful; for though the equatorial 

 regions of land might gather more heat from the 

 sun, and the polar regions receive more warmth by 

 oceanic communications, still these polar surfaces of 

 warmed water might lose more heat by radiation 

 into space than equal surfaces of snowy land ; and 

 thus the whole ocean might be cooler, as well as 

 more equal in temperature. Whatever changes we 

 suppose possible in the distribution of land and sea 

 must fall short of these extreme suppositions, which 

 besides do not so well match the phenomena of any 

 geological period, as to prevent our turning to other 

 causes of change not in the temperature of the 

 whole surface of the globe, but in the climates of 

 particular parts, still following the guidance of Lyell. 

 Of these two are very prominent ; the flowing of 

 oceanic currents, and the course of the winds ; and to 

 these a great and real influence is justly attributed, 

 in heating some parts of the earth above the average, 

 and in cooling other parts below it. Thus the well- 

 known broad and constant stream which flows from 

 the Gulf of Florida up the North Atlantic, carries a 

 vast body of warmed water from the tropical shores 



