1 74 Proceedlnffft of the Roi/al Societt/. 



avalanclies ; — tlio descent of trees, along the slide of Alpnacli ; — the 

 fact proved by the meteorological tables kept at the Hospice of the 

 Great St Bernard, when compared with the descent of Ilngi's hut on 

 the Aar Glacier, — that the greater the fall of snow in the upper re- 

 gions during winter, the greater is the descent of the glaciers during 

 the following summer; — and lastly, the f\\ctthat the higher the moun- 

 tain range (and ofcour.se the greater the quantity of ice or snow), the 

 lower was the level to which glaciers descend. He also endeavoured to 

 shew that the glaciers, or icy masses, covering the mountains, and 

 filling their vallies, at no part of their course are frozen to the soil on 

 which they rest; and that the temperature of the soil covered with 

 deep masses of snow or ice, was probably never below 32° Fahren- 

 heit. 



The author made a short digression here, to account for the pro- 

 bable cause of the former extension of glaciers, and their subse- 

 quent disappearance. He endeavoured to shew, that the scattered 

 boulders, &c. marking the former extension of glaciers, were all 

 over the surface of the older alluvium (diluvium of Buckland) and 

 he hence endeavoured to ascertain at what period that alluvium was 

 formed. After a full examination of the subject, and especially 

 from the examination of the fossil remains found in that alluvium, 

 he arrived at the conclusion, that the waters of the deluge were the 

 cause of the formation of that alluvium ; and he accounted for 

 the former extension of glaciers, by the known effect of water, in 

 the act of evaporating, producing cold, especially when acted on by 

 a brisk wind, which was the state of the earth immediately after 

 the deluge. The increased moisture in the atmosphere at this 

 period, he thought, would furnish ample supplies of snow and ice 

 for the purpose, and being first deposited on the elevated peaks, 

 would rapidly spread over all those extended surfaces which glaciers 

 are thought once to have covered. Their subsequent disappearance 

 he accounted for, by supposing that the icy or snowy. covering pre- 

 vented the loss by radiation of the heat received by the earth's crust 

 from the interior of the earth ; since this heat, gradually accumu- 

 lating below, would in time melt the icy masses at their lower ex- 

 tremities faster than they could be supplied from above, and thus 

 reduce them to their present dimensions. He illustrated this view, 

 by mentioning the fact, that the angular boulders, &c. are pretty 

 equally scattered over all the extended surfaces which glaciers are 



