Solar Energy in Relation to Ice. 143 



temperature of the cold currents of air, which are, so to 

 speak, continually waiting over our heads for an opportunity 

 to descend and chill our atmosphere to their own icy 

 temperature. 



It will be evident, from a consideration of these facts, how 

 delicately adjusted our climatal balance must be, and how 

 enormous must be the expenditure of Solar Energy required 

 to maintain the balance of temperature. A very slight 

 relaxation of Solar Energy suffices to turn this balance in the 

 wrong direction, and, by letting in icy-cold currents from 

 above, or by diverting the " Gulf Stream," to permit our 

 climate to relapse into the sub-frigid condition proper to its 

 latitude. 



It often snows on the Highland mountains when it is 

 raining on the low grounds of western Scotland, and when, 

 perhaps, there is neither rain nor snow on the east. Also, 

 it is often the case that snow lingers from year to year in 

 shady spots at high elevations, as for example, in the 

 Cairngorms or on Ben Nevis. If these mountain summits 

 stood higher by only a few hundred feet, there would probably 

 be twice as much snow as falls there now, and some of that 

 snow would certainly lie. Now, if the whole of western 

 Europe were elevated to about that level, something more 

 than these things would happen. Under these conditions 

 the aqueous component of the " Gulf Stream " would be 

 more than a hundred miles distant from the western shores 

 of the Scottish mainland. What is now the North Sea 

 would be a broad lowland, with the Ehine flowing north- 

 wards into the Atlantic at a point somewhere between the 

 north of Shetland and the south of Norway. Under these 

 conditions of elevation there could be no sidewash (as we 

 may term it) from the warm waters of the Atlantic into 

 the North Sea, the Irish Sea, and the English Channel. 

 Moreover, between the mainland of Scotland and the sea 

 margin to the west there would intervene a wide plain with 

 only a few eminences of any great elevation. Under such 

 conditions as these, which almost certainly represent the 

 geographical conditions that prevailed during the greater part 



VOL. XIV. K 



