Prof. Huxley on the Structure of Glacier Ice. 255 
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 him- 
self conclusively to demonstrate the fact. I must confess, how- 
ever, 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 con- 
tinuous 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 com- 
pressibility 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, @ 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 emboldened to say this much b 
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 trans- 
formations 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 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 (1), and p. 289 of the ‘ Systéme Glaciaire.’ 
I omitted to make the experiment detailed in (18). It is 
