98 DISCUSSIONS IN CLIMATOLOGY. 



resulting from those physical agencies called into 

 operation by an increase of eccentricity. To have 

 speculated on hypothetical geographical conditions 

 different from those which now obtain, and on the 

 influence which these may have had in bringing about 

 the glacial epoch, would have been on my part per- 

 fectly absurd, as I knew we had no evidence of the 

 existence of any such conditions. Besides, my aim was 

 to account for that epoch from known and established 

 facts and principles, without the introduction of hypo- 

 thetical causes. I fear that the fact of my making 

 little or no allusion to geographical conditions in my 

 explanations may have unfortunately led Mr. Wallace 

 and others to conclude that I altogether ignore, or, at 

 least, undervalue their importance, which is certainly 

 not the case. 



Although Mr. Wallace so frequently alludes to the 

 importance of geographical conditions, I am not sure if 

 he believes that during the glacial epoch those condi- 

 tions differed materially from what they are at present, 

 or that glaciation could have been greatly influenced 

 by any difference which did exist. 



7. Mr. Wallace alludes to one or two geographical 

 conditions which, if they had existed during the glacial 

 epoch, would have greatly aided glaciation; as, for 

 example, if a land-barrier had extended from the 

 British Isles, across the Faroe Islands and Iceland to 

 Greenland, cutting off from Northern Europe the 

 warm waters of the Atlantic, including the Gulf 

 Stream. "The result," he says, "would almost certainly 

 be that snow would accumulate on the high mountains 

 of Scandinavia till they became glaciated to as great 

 an extent as Greenland." 



It would be easy to multiply cases of this kind where 

 a distribution of land and water different from the 



