8 DISCUSSIONS IN CLIMATOLOGY. 



polar regions does not point to such high tempera- 

 tures being specially due to submergence of the polar 

 land. What has chiefly tended to retard the accept- 

 ance of the theory of secular changes of climate dis- 

 cussed in my work entitled ' Climate and Time,' is 

 the fact that physicists have not fully realised to 

 what an immense extent the climatic condition of 

 our globe is dependent upon the distribution of heat 

 by means of ocean currents. Were it not for the 

 enormous amount of heat transferred from equa- 

 torial to temperate and polar regions by means of 

 ocean currents, the globe would scarcely be habitable 

 by the present orders of sentient beings., When this 

 fact becomes fully recognised, all difficulties felt in 

 accounting for geological climate will soon disappear. 

 The climatic influence of ocean currents has not been 

 sufficiently considered, owing doubtless to the fact that 

 before I attempted to compute the absolute amount 

 of heat conveyed by the Gulf Stream, so as to com- 

 pare it with the amount directly received by the 

 Atlantic from the sun, no one had ever imagined that 

 that ocean in temperate and Arctic regions was de- 

 pendent to such an extent on heat brought from the 

 Equator. And this being so, it was impossible for any 

 one fully to realise to what an extent climate must 

 necessarily be affected by an increase or a decrease 

 of that stream. 



Sir William Thomson speaks of his theory being 

 that of Lyell; but beyond the mere assumption of the 

 submergence of the circumpolar land, the two theories 

 have little in common. Indeed, no one who believes 

 (as Sir William does) that the former warm climatic 

 condition of the polar area was mainly due to a trans- 

 ference of heat from equatorial to Arctic regions by 

 means of ocean currents can logically adopt Lyell's 



