270 Mr. J. Y. Buchanan [May 8, 



almost all the glaciers of Switzerland were, and had for long been 

 in an advanced state of decay, the Glacier des Bossons forming, as it 

 turned out, a temporary exception. Owing to the high external 

 temperature, I was obliged to creep into the innermost part of the 

 glacier in order to observe the relatively sHght effect of the agency, 

 which, in Hugi's case, produced such a striking effect in the broad 

 light of day. But, notwithstanding the fact that the advance of the 

 Glacier des Bossons which I witnessed in 1895 was shght and tem- 

 porary, it sufficed to show me the fundamental difference between 

 the effects produced by a glacier on its surroundings, according as it 

 is on the increase or on the decrease. When it is growing the 

 glacier is a living bearer of energy hke a river ; when it is shrinking, 

 it is inert as a salt lake. 



It has been noticed by those who have observed the occasional 

 advance of European glaciers in recent years, that there is little that 

 is gradual about their start. They get under way at once at a fair 

 speed, and proceed without delay in the work of handling the debris 

 that has accumulated in front of them during their repose. When 

 a glacier is really advancing there is no doubt about it ; where there 

 is doubt, it may be taken that the advance has not begun. 



External Work of a Glacier. — Owing to the enormous diminution 

 in the amount of land-ice in the course of the last half -century, we 

 are accustomed to talk of the retreat of the glaciers. But a glacier 

 never retreats ; it stops advancing, and melts where it stands. Even 

 in a stationary glacier, however, the flow of the ice in all its parts 

 continues ; but its effect outside of the glacier is almost if not quite 

 nil. In the stationary state its function in nature is conservation. 

 In the advancing state it adds the function of distribution. Its 

 destructive effect is very small. It protects the rock beneath it from 

 weathering, which is a chemical process, by the constant maintenance 

 of a low temperature and the practical exclusion of the atmosphere. 

 Any destructive action which it exerts must therefore be mechanical. 

 When two substances meet each other in mechanical strife it is 

 the harder that wears the softer, and in the strife between rock and 

 ice Nature makes no exception to this law. We have seen from 

 Hugi's description of a strife between rock and ice which went on 

 under his own eyes, what the effect was on the ice, which was at a 

 temperature much below that of melting. In a week or two, how- 

 ever, the evidence of the effect on the ice would be obhterated, great 

 though it was, while the reactive effect on the rock would remain, 

 but it is doubtful if it would be perceptible. In the battle between 

 ice and rock the ice suffers much ; the rock comes out with a scar 

 or two. The scars abide, but the destruction disappears and leaves 

 no record ; hence the neglect of the major effect and the exaggerated 

 importance generally attached to the minor. 



It has been said above that when the glacier begins to advance, it 

 performs a distributive function by digging up and pushing before it 



