Beport of the Besearches of M. Agasaiz. 171 



the investigation was at an end. But new difficulties arose in 

 connection with the researches concerning the method in which 

 glaciers advance in their onward course. Intimate relations 

 must of course exist between the form and arrangement of 

 the moraines, and the more or less accelerated movement of 

 the mighty mass. Hence arose the questions why certain 

 median moraines at first narrow, as in the median moraine of 

 the Aar, dilates in so remarkable a manner in the ultimate 

 course of the glacier, although no new materials are added to 

 it ; — why certain lateral moraines entirely disappear in their 

 course ; — and by the influence of what cause it is, that moraines, 

 after having formed very high ramparts, again become com- 

 paratively flat towards the extremity of the glacier. 



The question of movement or progress is that which has 

 always most engaged the attention of natural philosophers. 

 And it is the one which most merits attention, because, what- 

 ever theory be adopted, we must always come back to move- 

 ment before we can account for the existence of glaciers and 

 their preservation, in those positions in which they could not 

 have so formed themselves in situ. The displacements to 

 which glaciers are subjected, are too considerable and frequent, 

 even to be doubted by the native mountaineers, who regard 

 this state of matters only as natural. In their estimation, the 

 glacier is a river, which descends from the mountain, like 

 its torrents, only in a manner somewhat diff'erent. In fact, such 

 an intimate relation exists between a glacier and a river, that 

 the strongest possible parallelism naturally suggests itself to 

 the mind. A glacier is formed on the same principle, and is 

 composed of the same elements, as a river ; it is only water 

 under another form, which moreover occupies, as do torrents, 

 the bottom of valleys whose sinuosities it follows as if it were 

 really liquid. All this was so plain, that those who first di- 

 rected their attention to the subject, were at once convinced 

 of it. 



At the same time, when glaciers more particularly engaged 

 the attention of philosophers, they suggested other theories ; 

 and opinions diff'ered regarding the nature of their movement, 

 and the causes which produced it. Scheuchzer was the first who, 



