144 Proceedings of the Royal Physical Society. 



of the Glacial Period, our climatal conditions would be very- 

 different from what they are at present. Fuschias could not 

 then grow to the size of small trees, as they do out-of-doors 

 now in islands off the west of Scotland. Nor would palm 

 trees grow and grapes ripen as they do in those same parts. 

 With the aqueous component of the " Gulf Stream " more than 

 a hundred miles distant, a very marked lowering of the winter 

 temperature must have set in. But the aerial component 

 would probably remain in full force. It must have drifted, 

 under these conditions, across the " continental shelf " to the 

 Hebrides, and thence to the Highland mountains, much as it 

 does now. But the effects would be essentially different. 

 There would be on the western margin a wide belt where 

 much of the aqueous vapour would be chilled into fog ; 

 within that belt another of varying width in different parts, 

 where the precipitation took the form of rain ; and within that 

 still, and extending to the mountain centres, a zone where 

 instead of rain, there fell more or less snow. 



Kow Western Europe during the Glacial Period did, almost 

 certainly, stand several hundred feet higher above the sea- 

 level than it does at the present day. And I wish to 

 emphasise the opinion that, with the land at that level, and 

 with the "Gulf Stream" acting much as it does at the 

 present day, we should have all the conditions needful to 

 bring about a Glacial Period in both Britain and Scandinavia, 

 and that there is no need to invoke any other cause to 

 explain all the known facts relating to that remarkable 

 episode. 



With a copious precipitation, and its concomitant libera- 

 tion of heat, there would seem, at first sight, to be present 

 on our shores all the conditions for the amelioration, rather 

 than for the deterioration, of our climate. Why, then, it 

 may be asked, did it happen during the Glacial Period that 

 climatal conditions went on from bad to worse ? To give 

 a satisfactory answer to that question, requires that we should 

 first consider some additional factors connected with Solar 

 Energy in relation to Ice. One of the most important of 

 these lies in the fact that different substances warm up at 

 different rates in sunshine ; and another is, that the rays of 



