ON THE STRUCTURE OF GLACIER ICE 497 



coloured liquids cannot be made to enter it ; — and he admits that 

 the establishment of a complete system of fissures through a block 

 of ice, and its consequent permeability, are matters of time and 

 exposure (10). See also citation (i), and p. 289 of the ' Systeme 

 Glaciaire.' 



I omitted to make the experiment detailed in (13). It is singular 

 that in (12) Prof Agassiz states that '' the angular fragments and the 

 capillary fissures seem to disappear the moment the ice is covered," 

 while in (13) the operation is said to take some time ; but, supposing 

 the fact to be as Prof Agassiz says, it seems to me to be in the 

 highest degree probable that the fissures have reunited during the 

 interval. At any rate, I cannot admit Prof Agassiz's explanation, 

 for surely loose gravel is not exactly a substance calculated to " inter- 

 cept air and keep fissures full of water.'' 



It would take up too much space, and serve no useful purpose, to 

 quote at length the account Prof i'\gassiz gives of his infiltration 

 experiments (' Syst. Glaciaire,' pp. 170-179). Those who will turn to 

 the original, will find that they are all vitiated by the absence of any 

 discrimination between the deep and the superficial ice, and between 

 " capillary fissures " and accidental cracks. Not one of Prof Agassiz's 

 experiments affords the slightest evidence that capillary fissures are a 

 primitive and essential constituent of the structure of the deep ice of 

 a glacier. 



The experiments of the Messrs. Schlagintweit (/. c. p. 12) appear 

 to me to be equally inconclusive ; these gentlemen, like Prof Agassiz, 

 having omitted to take the precaution of clearing away the superficial 

 layer from the mouth of the cavity to be filled with the infiltration 

 fluid. Unless this be done, the superficial layer sucks up the coloured 

 liquid, which becomes diffused in the way they describe. And if the 

 cavity (as may readily happen, especially with such large ones as 

 those employed by these experimenters) communicates by an 

 accidental fissure with some other part of the surface of the glacier 

 (say the wall of a crevasse, or the roof of such a cavity as Prof. 

 Agassiz's infiltration gallery), it should be well remembered that the 

 fluid which drains through will not run out in a stream from the 

 termination of a crack, unless the superficial layer has been cleared 

 away ; otherwise, it will fill the fissures of the superficial layer and 

 appear as a great patch. The observer then, seeing nothing but 

 fissures full of coloured infusion at each end of the course of the fluid,, 

 naturally enough imagines that in its intermediate course the fluid 

 has traversed similar fissures. This conclusion would be at once 

 dissipated by cutting away the superficial layer and laying open the 



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