temperature affecting the whole mass of the interior of the globe
was believed to be presented in the small mean density of the earth, a
density not more than 5.66 times that of water, the mean density of the
solid surface being 2.7, and that of the solid and sea-surface together
1.6. But this is not a density answering to that which the earth should
have in virtue of the attraction of her own parts. It implied some agent
capable of rarefying and dilating, and the only such agent is heat.
Although the law of the increase of density from the upper surface to
the centre is unknown, yet a comparison of the earth's compression with
her velocity of rotation demonstrated that there is an increasing
density in the strata as we descend. The great fact, however, which
stands prominently forth is the interior heat.

Not only were evidences thus offered of the existence of a high
temperature, and, therefore, of the lapse of a long time by the present
circumstances of the globe; every trace of its former state, duly
considered, yielded similar indications, the old evidence corroborating
the new. And soon it appeared that this would hold good whether
considered in the inorganic or organic aspect.

[Sidenote: Inorganic proofs of a former high temperature.] In the
inorganic, what other interpretation could be put on the universal
occurrence of igneous rocks, some in enormous mountain ranges, some
ejected from beneath, forcing their tortuous way through thus resisting
superincumbent strata; veins of various mineral constitution, and, as
their relations with one another showed, veins of very different dates?
What other interpretation of layers of lava in succession, one under
another, and often with old disintegrated material between? What of
those numerous volcanoes which have never been known to show any signs
of activity in the period of history, though they sometimes occur in
countries like France, eminently historic? What meaning could be
assigned to all those dislocations, subsidences, and elevations which
the crust of the earth in every country presents, indications of a loss
of heat, of a contraction in diameter, and its necessary consequence,
fracture of the exterior consolidated shell along lines of least
resistance? And though it was asserted by some that the catastrophes of
which these are the evidences were occasioned by forces of unparalleled
energy and incessant operation--unparalleled when compared with such
terrestria