10 DISCUSSIONS IN CLIMATOLOGY. 



thereby reducing the temperature. Since, then, the 

 earth loses as well as gains the greater part of her 

 heat in equatorial regions, it is there that the sub- 

 stance best adapted for preventing the dissipation of 

 that heat must be distributed in order to raise the 

 general temperature. Now, of all substances in nature, 

 water seems to possess this quality in the highest 

 degree; and, being a fluid, it is adapted by means of 

 currents to carry the heat which it receives to every 

 region of the globe. 



It has been urged as an objection to any ocean- 

 current theory that, while it provides the requisite 

 amount of heat, it fails to remove the three or four 

 months' darkness of an Arctic winter, which must 

 have proved fatal to plants of the Miocene period. 

 This objection seems, however, to have no foundation 

 in fact. Sir Joseph Hooker stated to the Royal 

 Society, at the close of the reading of Prof. George 

 Darwin's paper, that palms and other plants brought 

 from the tropics survived the winter in St. Peters- 

 burg without damage, though matted down in absolute 

 darkness for more than six months ; and he was of 

 opinion that the want of sunlight during the Arctic 

 winter would not be very prejudicial to the plants. 



But a cause must be found as well for the cold of 

 the Glacial Epoch as for the warm climate of the 

 Arctic regions that obtained in Miocene times. Ac- 

 cording to Lyell the continents would require to be 

 moved to high temperate and polar regions to bring 

 about a glacial condition of things in Britain. But 

 this is an assumption which the present state of 

 geological science will hardly admit. It is perfectly 

 certain that there have been no such vast revolutions 

 in physical geography in post-Tertiary times. 



Tendency in Geology to Cataclysmic Theories. — 



