REPORT ON GEOLOGY. 
407 
of the present day ; but many of us may nevertheless be per? 
mitted to doubt, whether the same identity can be predicated 
of the general physical conditions affecting the surface of our 
planet at those earlier primordial periods, when as yet the 
series of rocks, constituting the whole mass of that portion of 
the terrestrial crust with which we are acquainted, were only 
beginning to be deposited ; since, even after the long interval 
which must have elapsed from the first primordial epoch of the 
micaceous slates, to the deposition of the carboniferous rocks, 
we are led to infer that, at this later and comparatively modern 
period, the surface of the globe was still chiefly oceanic, inter¬ 
spersed only with scattered groups of islands, having a tropi¬ 
cal temperature; while the animal inhabitants of that surface 
were restricted to shell-fish, Zoophytes, and possibly a few 
vertebrated fish, and still fewer Saurians; and its Flora exhibited 
only gigantic ferns, palms, Equisetaceae, and Coniferae. I would 
repeat then, that we may still perhaps be permitted to doubt, 
that an identity of physical conditions can be predicated of the 
surface of our planet between these periods and the present,— 
even without going as far back as a reviewer (and he a very 
favourable one,) has done, and referring to the original state of 
fluidity of the planet, as deduced from its spheroidal form. It 
may perhaps be the most truly philosophical rule to guide the 
spirit of our investigations, that whereas the actual operations of 
nature, and those indicated by geological observations, present 
certain points of analogy, and other points of difference,—so it is 
equally contrary to a sound spirit of inductive reasoning, to con¬ 
fine our attention exclusively to the one class of facts or to the 
other. It may be that former geologists have erred in restrict¬ 
ing their considerations too much to the class of differences,— 
and Mr. Lyell has done well to recall their minds to the contem¬ 
plation of the many analogies ; but that these alone deserve our 
regard is quite another thing. 
I now in conclusion proceed to offer the views, which are 
most impressed on my own mind, as to the present prospects of 
our science, and the objects which most claim our attention at 
this time, and promise most fairly to reward that attention. 
The first points of the science are undoubtedly those which 
connect it with its elder and far superior sister, Physical Astro¬ 
nomy. I mean such questions as those relating to the sphe¬ 
roidal figure *, and to the density, of the Earth ;—the inquiry 
* It has been well observed in a very able article in a late periodical, that 
“ the most conclusive argument against the fact of any disturbance having, in 
remote antiquity, taken place in the axis of the earth’s rotation, is to be found 
in the amount of the lunar irregularities which depend on the earth’s spheroidal 
figure. However insufficient the mere transfer of the mass of the ocean, from 
the old to the new equator, might be to ensure the permanence of the new axis, 
