out half this: but three-fourths
of the whole surface is water. Hence, we see that the materials of the
interior of the earth must be either metallic or very compressible. To
assign a metallic nucleus to the earth, is repugnant to analogy; and it
is not rendered even probable by facts, as we find volcanic emissions to
contain no heavier elements than the sedimentary layers. Besides, there
are indications of a gradual increase of density downwards, such as
would arise from the compressibility of the layers. Seeing, therefore,
the equilibrium of the whole mass, and the consequent hydrostatic
balance of the land in the sea,--seeing also the small compressibility
of the solid portions, and the great compressibility of the fluid, the
inference is legitimate that the whole is hydrostatically balanced, and
that our globe is a globe of water, with an intermediate shell of land,
specifically lighter than the fluid in which it is suspended. Where this
shell is of great thickness, it penetrates to greater depths, and
attains to greater elevations above the surface of the aqueous globe;
where it is less thick, it is found below the surface, and forms the
bottom of the upper ocean. Recent soundings give much greater depths to
some parts of the ocean, than the most elevated land upon the globe.
Captain Denham, of H. B. M. ship Herald, lately sounded in 37d south and
37d west, and found bottom at 7,706 fathoms, or about nine English
miles.

As the interior portions of our globe are totally unknown, and the
compressibility of water is well established, it is just as sane to
consider water the most abundant element of nature, as solid land. The
great question to ask is, whether there may not be other phenomena
incompatible with this supposition? It is plain that the permanency of
terrestrial latitudes and longitudes would be unaffected by the
conditions we have supposed. Would the precession of the equinoxes be
also unaffected? Mr. Hopkins has entered into such an investigation, and
concludes: "Upon the whole, then, we may venture to assert that the
minimum thickness of the crust of the globe, which can be deemed
consistent with the observed amount of precession, cannot be less than
one-fourth or one-fifth of the radius of the earth." These
investigations were made on the hypothesis of the interior fluidity
being caused by the fusion of the central portions of a solid globe; but
it is evident that the analytical result would be the same