ting
primarily in the vertical, but in _tangential pressures acting
horizontally, and resolved by mutual pressures at certain points into
vertical resultants_. These Prevost rightly attributed to the
contraction of the earth's solid crust. The same idea has been adopted
by Elie de Beaumont as the true mechanism of the elevation of mountain
ranges; and although De Beaumont's views as to the thinness he assigns
to the solid and contracting crust, and his strange deduction as to the
parallelism of contemporaneous mountain chains uplifted by its spasmodic
action along certain lines, may be untenable, his notion generally as to
the play of forces producing mountain elevation is much more nearly
correct.

Mr. Hopkins's notion is simply that of the geologists. Anyone who reads
his well-known papers on elevation and the formation of fissures, etc.,
must see that he views all elevatory forces as of liquids or
quasi-liquids forced up and acting primarily _vertically_ upon the
strata above them, and that these strata are not under tangential
compression, but under tension. Hence the mathematical deductions
contained in those papers as to the directions in which elevatory forces
act, and in which fissures are formed by them, are not in any way a
setting forth of such facts as occur in Nature, and, much attention as
they have attracted, can only now be viewed as exercises of mathematical
skill misapplied, because based upon data not to be found in Nature. In
fact, those papers do but misrepresent Nature, and, like many other
mathematical investigations based on untrue or insufficient data, have
tended to retard knowledge.

The views which I have put forward in the Paper I have referred to, read
to the Royal Society, recapitulated in skeleton, so to say, are as
follows. Omitting those portions which treat of our globe from the
period of the first liquefaction out of a nebulous condition, and of the
earliest stages of the cooling by radiation into space, when the crust
was extremely thin, and of the deformation of the spheroid as one of the
first effects of its contraction, and through that the general shaping
out of continents and ocean beds; I have endeavoured to show that the
rate of contraction of the crust, while very thin, exceeded that of the
large fluid nucleus supporting it, and so gave rise to _tangential
tensions_ in the crust, and fracturing it into segments; next, that as
the crust thickened, these _tensions_ were gradu