he introduction of a very little mud, and without any
degree of concretion; muddy water, indeed, cannot be made to pass
through such a body without compacting it so; and this every body finds,
to their cost, who have attempted to make a filter of that kind.

But I shall suppose Lasius has informed our author that there had been
a petrifaction in this case; and, before I admit this example of the
formation of granite, I must ask what sort of a granite it was;--whether
of two, three, or four ingredients; and, how these were disposed. If,
again, it were not properly a granite, but a stone formed of granite
sand, What is the cementing substance?--Is it quartz, felt-spar, mica,
or schorl?--or, Was it calcareous? If our author knows any thing about
these necessary questions, Why has he not informed us, as minutely as
he has done with regard to the dimensions of the mole, with which we
certainly are less concerned? If, again, he knows no more about the
matter than what he has informed us of, he must have strangely imposed
upon himself, to suppose that he was giving us an example of the
_formation of granite in the moist way_, when he has only described an
effectual way of retaining water, by means of sand and mud.

CHAP. III.

Of Physical Systems, and Geological Theories, in general.

In the first chapter I have given a general theory of the earth,
with such proofs as I thought were sufficient for the information of
intelligent men, who might satisfy themselves by examining the facts on
which the reasoning in that theory had been founded.

In the second chapter, I have endeavoured to remove the objections which
have been made to that theory, by a strenuous patron of the commonly
received opinion of mineralogists and geologists,--an opinion which, if
not diametrically opposite, differs essentially from mine. But now I am
to examine nature more particularly, in order to compare those different
opinions with the actual state of things, on which every physical theory
must be founded. Therefore, the opinions of other geologists should be
clearly stated, that so a fair comparison may be made of theories which
are to represent the system of this earth.

Now, if I am to compare that which I have given as a theory of the
earth, with the theories given by others under that denomination, I
find so little similarity, in the things to be compared, that no other
judgment could hence be formed, perhaps, than that they had little or