THE CLIMATE OF GREAT BRITAIN. 273 



the heat-radiating power of a continent really influenced 

 the country lying to the north, it should tend to lower 

 rather than raise the temperature, for the ascending 

 currents of air would strengthen the currents of colder 

 air pouring in from the north, and these currents 

 on Humboldt's assumption that the country directly to 

 the north is that affected would lower the mean 

 annual temperature. It would only be exceptionally 

 that the warmer returning currents would descend, and 

 thus exalt the temperature. It seems clear, however, 

 that Asia is the continent chiefly affected by the heat- 

 radiating power of Africa ; since the cold currents from 

 the north travel eastwards, while the warm return- 

 current has a westerly motion. We should thus attri- 

 bute the milder climate of Europe rather to the 

 influence of the tropical parts of the Atlantic Ocean, 

 than to the cause assigned by Humboldt, and we 

 should invert the effects he attributes to oceans and 

 continents respectively. With this change somewhat 

 a bold one, I confess 1 we may say that all the non- 

 variable causes tending to exalt temperature operate in 

 England's favour. 



The constant causes tending to lower temperature 

 are simply the converse of those above considered. 



1 Not unsupported, however, by good authority. Thus Professor 

 Nichol, speaking of the climate of Europe, writes : ' The air that rises 

 in Africa blows rather over Asia than Europe. The cradle of our 

 winds is not in Sahara but in America.' Again, Kaemte notices, that 

 if the effects of oceans and continents were those assigned by Humboldt, 

 we should find in the western parts of America a colder climate than 

 in the eastern parts ; the reverse, however, is the case. 



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