158 JReport of the Researches ofM. Agassiz. 



thod in which the glaciers pass the projections of the rocks, 

 and in the following way. In the space included by this 

 band on the left bank, there exist two of these rocky promon- 

 tories. These very marked projections obstruct the passage 

 of the ice to an extent of not less than 600 feet, and force it 

 to diverge into a lateral creek. According, therefore, to the 

 manner in which the mass shall pass these projections, we may 

 deduce conclusions for or against the several theories which 

 have been proposed. 



The two lines of the transversal band which we have above 

 described, having been measured by Mr Wild between the 

 13th and 16th of July, he repeated the measurement on the 

 30th of August, and found that, during these 45 days, the 

 central portion had already advanced considerably more than 

 the sides, the former part having moved forward 30 feet 5 

 inches, whilst the movement of the latter parts of the glacier 

 diminished towards the margin nearly in the ratio of its dis- 

 tance from the central moraine. 



It is, moreover, of some consequence that we should be 

 made acquainted with the relations of the movement in dif- 

 ferent directions. Accordingly, a large triangle was traced on 

 the 12th of July, on the course of the Finster-Aar, imme- 

 diately above the hotel. One of the sides A B, which was 

 perpendicular to the axis of the glacier, measured 301 feet ; 

 the second A C, which was nearly parallel to the axis, mea- 

 sured 409 feet ; and the third B C, the hypotenuse, measured 

 492 feet 4 inches. This triangle was again measured on two 

 subsequent occasions, namely, on the 23d of July and on the 

 30th of August. On the first occasion, a slight difference only 

 was remarked in the line A B, which was shortened about 

 7 inches ; and on the 30th of August the following- were the 

 measurements : — The line A B equalled 299 feet 5 inches ; 

 the line A C 409 feet 6 inches ; and the line B C 492 feet 

 5 inches. Hence it results, that the side perpendicular to the 

 axis of the glacier had alone been shortened, as might natu- 

 rally have been expected ; whilst the side parallel to the axis 

 of the glacier had, on the contrary, been elongated 6 inches, 

 and the hypotenuse remained the same. 



But our observations should not be limited to the deter- 



