352 LOUIS AGASSIZ. 



than during the day. This was explained by 

 the fact that the fissures were then free from 

 any moisture arising from surface melting, so 

 that the passage through them was unim- 

 peded. 1 



The comparative rate of advance in the 

 different parts of the glacier was ascertained 

 this summer with greater precision than before. 

 The rows of stakes planted in a straight line 

 across the glacier by Agassiz and Escher de 

 la Linth, in the previous September, now de- 

 scribed a crescent with the curve turned to- 

 ward the terminus of the glacier, showing, 

 contrary to the expectation of Agassiz, that 

 the centre moved faster than the sides. The 



1 Distrust has been thrown upon these results by the fail- 

 ure of more recent attempts to repeat the same experiments. 

 In reference to this, Agassiz himself says : " The infiltra- 

 tion has been denied in consequence of the failure of some 

 experiments in which an attempt was made to introduce 

 colored fluids into the glacier. To this I can only answer 

 that I succeeded completely myself in the self-same experi- 

 ment which a later investigator found impracticable, and that 

 I see no reason why the failure of the latter attempt should 

 cast a doubt upon the success of the former. The explana- 

 tion of the difference in the result may perhaps be found in 

 the fact that as a sponge gorged with water can admit no 

 more fluid than it already contains, so the glacier, under cer- 

 tain circumstances, and especially at noonday in summer, may 

 be so soaked with water that all attempts to pour colored 

 fluids into it would necessarily fail." See Geological Sketches, 

 by L. Agassiz, p. 236. 



