ently accomplished. Note,
however, that we have no clear evidence, hitherto, of the time taken to
produce any of them. We know that a change of temperature alters the
position and the angles of the atoms of crystals, and also the entire
bulk of rocks. We know that in all volcanic, and the greater part of all
subterranean, action, temperatures are continually changing, and
therefore masses of rock must be expanding or contracting, with infinite
slowness, but with infinite force. This pressure must result in
mechanical strain somewhere, both in their own substance, and in that of
the rocks surrounding them; and we can form no conception of the result
of irresistible pressure, applied so as to rend and raise, with
imperceptible slowness of gradation, masses thousands of feet in
thickness. We want some experiments tried on masses of iron and stone;
and we can't get them tried, because Christian creatures never will
seriously and sufficiently spend money, except to find out the shortest
ways of killing each other. But, besides this slow kind of pressure,
there is evidence of more or less sudden violence, on the same terrific
scale; and, through it all, the wonder, as I said, is always to me the
delicacy of touch. I cut a block of the Saleve limestone from the edge
of one of the principal faults which have formed the precipice; it is a
lovely compact limestone, and the fault itself is filled up with a red
breccia formed of the crushed fragments of the torn rock, cemented by a
rich red crystalline paste. I have had the piece I cut from it smoothed,
and polished across the junction; here it is; and you may now pass your
soft little fingers over the surface, without so much as feeling the
place where a rock which all the hills of England might have been sunk
in the body of, and not a summit seen, was torn asunder through that
whole thickness, as a thin dress is torn when you tread upon it.

(_The audience examine the stone, and touch it timidly; but
the matter remains inconceivable to them._)

MARY (_struck by the beauty of the stone_). But this is almost marble?

L. It is quite marble. And another singular point in the business, to my
mind, is that these stones, which men have been cutting into slabs, for
thousands of years, to ornament their principal buildings with,--and
which, under the general name of 'marble,' have been the delight of the
eyes, and the wealth of architecture, among all civilised nations,--are
p