iven of the mechanism of the glacier, in connection with its structure,
are presented in the language of the unprofessional observer, without
any attempt at the technicalities of the physicist. I do not wonder,
therefore, that those who have looked upon the glacier chiefly with
reference to the physical and mechanical principles involved in its
structure and movement should have found my Natural Philosophy
defective. I am satisfied with their agreement as to my correct
observation of the facts, and am the less inclined to quarrel with the
doubts thrown on my theory since I see that the most eminent physicists
of the day do not differ from me more sharply than they do from each
other. The facts will eventually test all our theories, and they form,
after all, the only impartial jury to which we can appeal. In the mean
while, I am not sorry that just at this moment, when recent
investigations and publications have aroused new interest in the
glaciers, the course of these articles brings me naturally to a
discussion of the subject in its bearing upon geological questions. I
shall, however, address myself especially, as I have done throughout
these papers, to my unprofessional readers, who, while they admire the
glaciers, may also wish to form a general idea of their structure and
mode of action, as well as to know something of the important part they
have played in the later geological history of our earth. It would,
indeed, be out of place, were I to undertake here a discussion of the
different views entertained by the various students who have
investigated the glacier itself, among whom Dr. Tyndall is especially
distinguished, or those of the more theoretical writers, among whom Mr.
Hopkins occupies a prominent position.

Removed, as I am, from all possibility of renewing my own observations,
begun in 1836 and ended in 1845, I will take this opportunity to call
the attention of those particularly interested in the matter to one
essential point with reference to which all other observers differ from
me. I mean the stratification of the glacier, which I do not believe to
be rightly understood, even at this moment. It may seem presumptuous to
dissent absolutely from the statements of one who has seen so much and
so well as Dr. Tyndall, on a question for the solution of which, from
the physicist's point of view, his special studies have been a far
better preparation than mine; and yet I feel confident that I was
correct in de