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lowed no dilatation can take place ; that it was unlikely water could 

 percolate during the course of one day through a solid mass of ice, 

 more than 100 feet thick, especially when that ice was colder than 

 the freezing point of water ; that pools of water (in the Polar Re- 

 gions) remained unfrozen for whole weeks during the summer whilst 

 their progressive motion was greatest. For these and other reasons, 

 the author arrived at the conclusion " that glaciers do not advance 

 in consequence of a process of dilatation of their icy mass." 



The author next enquired into the proofs of the truth of the 

 sliding theory, and stated, that he had satisfied himself that every 

 phenomenon known to occur in glaciers could be explained by it. 

 He brought forwards, as explanatory circumstances, the descent of 

 avalanches; — the descent of trees, along the slide of Alpnach ; — the 

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

 Gi-eat St Bernard, when compared with the descent ofHugi'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 fact that the higher the moun- 

 tain range (and of course 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 disappeai-ance. 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 

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



