An Expository Outline of the Vestiges of the Natural History of Creation | Page 8

nearer home and more within cognizance, the work seems
finished, perfect, and unchangeable, and, like the Great Architect, made
to endure for ever. This was the conclusion of LAPLACE; he proved
that the state of our system is stable; that is, the ellipsis the planets
describe will always remain nearly circular, and the axis of revolution
of the earth will never deviate much from its present position. He also
gave a mathematical proof that this stability is not accidental, but the
result of design, of an arrangement by which the planets all move in the
same direction, in orbits of small eccentricity and slightly inclined to
each other. Reasoning from analogy, as the author of the Vestiges is
prone to do--extending our views from our solar system to other
systems--other suns and revolving planets--it is fair to conclude that
they are not less perfect in arrangement--subject to like conditions of
permanency, and alike exempt from mutation, decay, collision, or
extinction.
Descending from this high region, we accompany the author to his next
and lower field--the
EARTH AND ITS GEOLOGICAL HISTORY.
Our globe is somewhat less than 8,000 miles in diameter; it is of a
spheroidal form, the equatorial exceeding the polar axis in the
proportion of 300 to 299, and which slight inequality, in consequence
of its diurnal revolution, is necessary to preserve the land near the
equator from inundation by the sea. The mean density or average
weight of the earth is, in proportion to that of distilled water, as 5.66 to
1. So that its specific gravity is considerably less than that of tin, the
lightest of the metals, but exceeds that of granite, which is three times
heavier than water.
Descending below the surface, the first sensation that strikes is the
increase of temperature. This is so rapid, that for every one hundred
feet of sinking we obtain an increase of more than one degree of
Fahrenheit's thermometer. If there be no interruption to this law, and no
reason exists to conclude there is, it is manifest that at the depth of a
few miles we must reach an intensity of heat utterly unbearable. Hence
it follows that by no improvements in machinery can mining operations

be carried down to a great depth below the surface. The greatest depth
yet penetrated does not exceed three thousand feet, and forms a very
small advance towards the earth's centre, distant 4,000 miles.
Geologists, however, without penetrating far into the earth, have found
means for obtaining an insight for several miles into its interior
structure, and armed with hammer, chisel, and climbing hook, they
explore the beetling sea-cliff, traverse the deepest valleys, and scale the
highest mountains, carefully examining their formation, disposition,
and substance, and are thus enabled to obtain some knowledge of the
earth's stomach, as it were, by scrutinising the deposits and eruptive
ejectments on its surface. For example, we come to a mountain
composed of a particular substance with strata or beds of other rock
lying against its sloped sides; we, of course, infer that the substance of
the mountain dips away under the strata that we see lying against it.
Suppose that we walk away from the mountain across the turned-up
edges of the stratified rocks, and that for many miles we continue to
pass over other stratified rocks, all disposed in the same way, till we
begin to cross the opposite edges of the same beds; after which we pass
over these rocks all in reverse order, till we come to another extensive
mountain composed of similar materials to the first, and shelving away
under the strata in the same way; we should then infer that the stratified
rocks occupied a basin formed by the rocks of these two mountains,
and by calculating the thickness right through these strata could say to
what depths the rock of the mountain extended below. In this way has
the interior of the globe been examined, and its contents and
arrangement, for several miles below the surface, ascertained. The
result of such inspection we leave the author of the Vestiges to
describe:--
"It appears that the basis rock of the earth, as it may be called, is of
hard texture, and crystalline in its constitution. Of this rock, granite
may be said to be the type, though it runs into many varieties. Over this,
except in the comparatively few places where it projects above the
general level in mountains, other rocks are disposed in sheets or strata,
with the appearance of having been deposited originally from water.
But these last rocks have nowhere been allowed to rest in their original

arrangement. Uneasy movements from below have broken them up in
great inclined masses, while in many cases there has been projected
through the rents rocky matter more or less resembling the