tn the Ice of Glaciers. 87 
and still more in forming a theory in the least plausible re- 
specting its origin. 
Its importance, however, as an indication of an unknown 
cause, is very great; not only because all that can illustrate 
what is so obscure as the manner of glacier formation and 
movement, is so, but because it is precisely on this very point 
of “ What is the internal structure of the ice of a glacier?’ 
that the question now pending respecting internal dilatation 
as a force producing progression, mainly hangs. Some con- 
sider ice as compact, others as granular ; some as crystallized, 
others as fractured into angular fragments ; some as horizon- 
tally stratified, others as homogeneous; some as rigid, others 
as plastic ; some as wasting, others as growing; some as ab- 
sorbing water, others as only parting with it ;—and yet no one 
seems to have observed, or at least observed as an object of 
study, this pervading slaty or ribboned structure, to be found 
probably in one part or other of every true glacier. 
With regard to exéent, this structure was observable on the 
Lower Glacier of the Aar, from its lower extremity up to the 
region of the /firn or nevé, where, the icy structure ceasing to 
exist, it could not be looked for; yet even there, where fre- 
quent thaws, induced by the neighbourhood of rocks or stones, 
produced a compacter structure, the veins became apparent. 
In some parts of the glacier, it appears more developed than 
in others: in the neighbourhood of the moraines, and the walls 
of the glacier, it was most apparent. This would seem to in- 
fer a relation to the frequency of thaws and recongelation. 
It penetrates the thickness of the glacier to great depths. 
It is an integral part of its inmost structure. That it could 
not be the production of a single season I was speedily con- 
vinced, by observing that where old crevices fissured the gla- 
cier transversely, the veined structure not only was reproduced 
on either side, but frequently with a sift or dislocation, or 
series of parallel fissures, presenting sometimes a series of dis- 
locations advancing in one direction. 
The course of the veined structure was, generally speaking, 
on the Glacier of the Aar, strictly parallel with its length, and 
that with a degree of accuracy which seems extraordinary, if 
we attribute its production to the remote influence of the re- 
