Mr. Hopkins’s Abstract of his Memoir on Physical Geology. 365 
blems, to which it is strictly applicable, and which are chosen 
so as to bear the closest analogy to the corresponding ones 
which nature presents to us; and it is simply on the strictness 
of this analogy that we are called upon to decide, in judging 
of the admissibility of our mode of investigation. It is im- 
portant to have a clear conception of this principle, on which 
the application of strict analysis to the problems of nature 
must always be made. In fact, this is the principle on which 
every one must tacitly (sometimes perhaps unconsciously) pro- 
ceed, in forming a distinct idea of the necessary relations be- 
tween any physical cause acting under complicated conditions, 
and its remoter consequences. We must form our conclu- 
sions from the consideration of some comparatively simple 
but strictly analogous case, and apply them to the actual one, 
with such limitations as circumstances may require. The 
advantage which the mathematician possesses, consists in this 
—that the standard case to which he refers his more complex 
problem, is a definite one, from which he has means of de- 
ducing his results free from that uncertainty which necessarily 
attends other modes of investigation. It is a standard case of 
this kind, which I have endeavoured to supply for geological 
theories of elevation; nor am I without hopes, that the attempt 
may at least so far succeed as to remove some of that inde- 
finiteness on this subject, by which the earlier speculations in 
every science must almost necessarily be characterized. More 
particularly, perhaps, may this be asserted of geology, which, 
notwithstanding the rapidity of its growth, is yet hardly strong 
enough to emerge from the cloudiness in which its phraseo- 
logy alone, with reference to the phenomena of elevation, by 
addressing itself more to the imagination than the judgement 
of the student, has sometimes been sufficient to involve it. An 
impression has thus been too frequently created, that little 
hope exists of elevating the science to any rank among the 
stricter physical sciences. Such a notion, however, appears 
to me most fatal to its healthy progress. The author of the 
Principles of Geology, whatever may be thought of some of 
his theoretical views, must be allowed by all to have set us an 
example well calculated to improve in this respect the tone of 
' geological speculation, in as much as he has boldly grappled 
with the difficulties of his problems in detail, and not been 
content to meet them with indeterminate generalities. In 
these investigations I have endeavoured to act upon the same 
principle, as the only one on which, if we are to speculate at 
all, we can speculate with safety; and if, perchance, a some- 
what vagué and misty sublimity which has appertained to this 
