of Secular Changes of Climate. 103 



consider how the condition of south temperate America at the 

 present day is explicable if they reject this agency. The line of 

 perpetual snow in the southern Andes is so low as 6000 feet in the 

 same latitude as the Pyrenees ; in the latitude of the Swiss Alps, 

 mountains only 6200 feet high produce immense glaciers which 

 descend to the sea-level ; while in the latitude of Cumberland, 

 mountains only from 3000 to 4000 feet high have every valley 

 filled with streams of ice descending to the sea-coast and giving 

 off abundance of huge icebergs. Here we have exactly the con- 

 dition of things to which England and Western Europe were sub- 

 jected during the latter portion of the glacial epoch, when every 

 valley in Wales, Cumberland, and Scotland had its glacier ; and to 

 what can this state of things be imputed, if not to the fact that 

 there is now a moderate amount of eccentricity and the winter 

 of the southern hemisphere is in aphelion ? The mere geogra- 

 phical 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° E. as compared with the same season in the northern 

 hemisphere."— P. 142. 



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 northward-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 Q Climate and Time,' chap- 

 ters v. and xiii., 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 intertropical waters of 

 the northern hemisphere are between three and four degrees 

 warmer than those of the southern. Another result which 

 follows, as has also been shown, is that the great equatorial 

 currents are made to lie at some distance to the north of the 



