496 ON THE STRUCTURE OF GLACIER ICE 



If the extract (8) were to be taken merely as a description of the' 

 superficial layer of a glacier, I should only have to object, that, so far 

 as I have been able to observe, the colour of the disintegrated blue 

 veins is not much affected by the water they contain, and that no. 

 amount of watery infiltration will confer on the white ice the beautiful' 

 transparency and colour of the blue veins. But Prof Agassiz over 

 and over again affirms that the whole substance of the glacier is. 

 traversed by capillary fissures, and his infiltration experiments are 

 supposed by himself conclusively to demonstrate the fact. I must 

 confess, however, that I have neither been able to observe what Prof - 

 Agassiz supposes he has observed, nor, were our observations in, 

 unison, could I admit his explanations. 



Take for instance the citation (9). How can the elasticity of the 

 air-bubbles influence the formation of fissures in the continuous mass 

 of rigid and eminently brittle ice which encloses them ? How is the 

 statement, that the ice becomes more rigid as the fissures are^ 

 developed in it, these fissures being supposed to be filled with water,, 

 compatible with that made in (2), that this same water is the chief 

 source of the plasticity and compressibility of ice ? 



Again, I am at a loss to understand the " diathermanicity " theory. 

 Prof Agassiz brings forward no experimental proof that air contained 

 within ice is more heated by the sun's rays than the ice itself; and,, 

 a priori, it seems improbable that the more diathermanous body 

 should be more heated than the less. It is true, I cannot pretend to. 

 have " followed the progress of modern physics ; " but I am em- 

 boldened to say this much by the fact, that you, who have, seem to 

 find at least equal difficulty in adopting Prof Agassiz's explanation. 



With regard to the experiments detailed in (10), (12), and (13), it 

 will be observed that my results in the main agree with those of Prof. 

 Agassiz, if, as before, we confine ourselves to the superficial layer ; but, 

 as I have shown, it is an error to extend the conclusions drawn from the 

 structure of the superficial layer to the deep ice. This, however, is what 

 Prof Agassiz has done ; and it is curious to find him in (12) refusing 

 to follow out a suggestion which would have led to the solution of his 

 difficulty, because it is "contrary to all we know of the transformations 

 of the ice." What do we know at present of the transformations of" 

 the ice ? 



It is important to remark again, that as regards matters of fact,. 

 Prof Agassiz's statements with respect even to the deep ice are, so far 

 as they go, not essentially different from mine. He admits (12) that 

 no fissures are at first visible in the deep ice ; — had he taken the 

 trouble to make the experiment, he would have found also that 



