MODIFICATION OF THEORY EXAMINED. 113 



the southern hemisphere is in aphelion ? The mere geo- 

 graphical position of the southern extremity of America 

 does not seem especially favourable to the production of 

 such a state of glaciation. The land narrows from the 

 tropics southwards, and terminates altogether in about the 

 latitude of Edinburgh ; the mountains are of moderate 

 height; while during summer the sun is three millions 

 of miles nearer, and the heat received from it is equivalent 

 to a rise of 20° F. as compared with the same season in the 

 northern hemisphere." * 



In a similar glacial condition are the islands of 

 South Georgia, South Shetland, Graham Land, Enderby 

 Land, Sandwich Land. There can be little doubt that 

 the present extension of ice in the Antarctic regions 

 is to a considerable extent due also to the influence of 

 eccentricity. 



Let us now glance for a moment at the influence 

 which this state of things has at present on north- 

 ward-flowing currents. One result is that the south- 

 east trades are stronger than the north-east, and as a 

 consequence blow over on the northern hemisphere ten 

 or fifteen degrees beyond the equator. This has the 

 effect, as has been shown (' Climate and Time,' Chapters 

 V. and XIIL, and other places), of impelling the warm 

 surface-water of the southern intertropical regions over 

 on the northern hemisphere. It is possible that the 

 greater strength of the south-east trades may to some 

 extent be due to the preponderance of ocean on the 

 southern hemisphere ; but there can be little doubt 

 that it is mainly the effect of eccentricity. 



The result of this transference of water from the 

 southern to the northern hemisphere is that the inter- 

 tropical waters of the northern hemisphere are between 

 three and four degrees warmer than those of the 



* " Island Life," p. 142. 



I 



