246 FKAGMENTS OF SCIENCE. 



permit the adherent of the erosion theory to make a 

 similar assumption. 



The influence of small accidents on the direction of 

 rivers is beautifully illustrated in glacier streams, which 

 are made to cut either straight or sinuous channels by 

 causes apparently of the most trivial character. In 

 his interesting paper ' On the Lakes of Switzerland,' 

 M. Studer also refers to the bend of the Ehine at 

 Sargans in proof that the river must there follow a 

 pre-existing fissure. I made a special expedition to the 

 place in 1 864 ; and though it was plain that M. Studer 

 had good grounds for the selection of this spot, I was 

 unable to arrive at his conclusion as to the necessity of 

 a fissure. 



Again, in the interesting volume recently published 

 by the Swiss Alpine Club, M. Desor informs us that 

 the Swiss naturalists who met last year at Samaden 

 visited the end of the Morteratsch glacier, and there 

 convinced themselves that a glacier had no tendency 

 whatever to imbed itself in the soil. I scarcely think 

 that the question of glacier erosion, as applied either to 

 lakes or valleys, is to be disposed of so easily. Let me 

 record here my experience of the Morteratsch glacier. 

 I took with me in 1864 a theodolite to Pontresina, 

 and while there had to congratulate myself on the 

 aid of my friend Mr. Hirst, who in 1857 did such 

 good service upon the Mer de Glace and its tribu- 

 taries. We set out three lines across the Morteratsch 

 glacier, one of which crossed the ice-stream near the 

 well-known hut of the painter Georgei, while the two 

 others were staked out, the one above the hut and the 

 other below it. Calling the highest line A, the line 

 which crossed the glacier at the hut B, and the lowest 

 line C, the following are the mean hourly motions of 

 the three lines, deduced from observations which ex 



