CLOUDS AND HI VERS, ICE AND GLACIERS, 155 



§ 57. Glacier Theories. 



390. You have not forgotten, and hardly ever can 

 forget, our climbs to the Cleft Station. Thoughts were 

 then suggested which we have not yet discussed. We 

 saw the branch glaciers coming down from their neves, 

 welding themselves together, pushing through Trela- 

 porte, and afterwards moving through the sinuous 

 valley of the Mer de Glace. These appearances alone, 

 without taking into account subsequent observations, 

 were sufficient to suggest the idea that glacier ice, how- 

 ever hard and brittle it may appear, is really a viscous 

 substance, resembling treacle, or honey, or tar, or 

 lava. 



§ 58. Dilatation and Sliding Theories. 



391. Still this was not the notion expressed by the 

 majority of writers upon glaciers. Scheuchzer of 

 Zurich, a great naturalist, visited the glaciers in 1705, 

 and propounded a theory of their motion. Water, he 

 knew, expands in freezing, and the force of expansion is 

 so great, that thick bombshells filled with water, and 

 permitted to freeze, are, as we know (312), shattered to 

 pieces by the ice within. Scheuchzer supposed that the 

 water in the fissures of the glaciers, freezing there and 

 expanding with resistless force, was the power which 

 urged the glacier downwards. He added to this theory 

 other notions of a less scientific kind. 



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