Year: 1871

Is the Interior Of the Earth


SeIid or FIuidl


Although the doctrine that the earth
is molten sphere, surrounded by q
thin crust of solid matter, was once
almost universally taught by geolog-
lists, there have of late years been
brought forward several arguments to
the contratry, which, apparently, are
more in favor of it's being a solid, or
nearly solid mass throughout; and
these arguments are fully entitled 20
our consideration, as our object is not
TO defend any particular theory but to
arrive as nearly as we can, at the truth
| will, therefore, in the first place, pro-
ceed to scrutiniZe all which has been
brought forward i'll opposition to the
| older hypothesis, and then to consider
whether any other explanation yet adj
vanced is more in accordance with the
facts of the case.


First of all, we are to answer the
| question as to whether it is possible
! for such a thin crust to remain solid
aud not at once to become melted up
and absorbed into the much greater
mass of molten matter beneath it Z?
This latter would doubtless be the case,
if the fluid mass had any means of
keeping up its high temperature, indie
| pendently of the amount of heat it
actually possessed when it originally
assumed the form of an igneous globe.
The question, howey er, in reality an
swers, in the negative, since it is evil
! dent that no crust could even COM
mcncc to form on the surface, unless
the sphere Itself was at the moment
actually giving off more heat, from lis
outer surface to the surrounding at
moSphere, than it could supply from
its more central parts in order to keep
the whole in n perfectly fluid condi-
| ton; 80 that when once such a crust,
however thin, had formed upon the
surface, it is self-evident that it could
not again become melted up or re-ab-
sorbed into the fluid mass below.


This external process, of solidifica-
tiOn due TO refrigeration would then
continue going on from the outside in
wards, until thickness of crust had
been attained sufficient to arrest, or
neutralize lowing to its bad conducti-
bility of heat both the cooling action
| of the surrounding air and the loss of
more heat from the molten mass with
i'm and thus q stage would soon be ar
rived at when both these actions would
| SO cOunter-balance on another, that
| the further cooling down of the earth
could be all but arrested condition
/ ruling at the present time, since the
earth-surface, at this moment, so far
! from receiving any, or more than a
minute amount of heat from the inte-
rior, appears to depend entirely, as re-
CARDS its temperature, upon the heat
/ which it receives from the suns rays.


We have next TO consider the argu-
ment that, il the earth's exterior were
in reality only such a thin covering,
| or crust, like the shell of an egg, to
which il has often been likened, that
such thickness would be altogether
insufficient to give to it that stability
which we know it to possess, and that,
consequently, il could never sustain
the enormous weight of is mountain
ranges, such as, for example, the Hi
malayas of Asia, or the Andes of a.
IneriCa, which are, AZ it were, masses
of rock piled up high above its mean
surlace-level.


At first sight, this style of reasoning
not only appears plausible, but oven
seems To threaten TO upset the entire
hypothesis altogether ltTequires but
little sober consideration, however, to
prove that il is rather, so to speak, SEN
satiomal i'm character than actually
founded on the facts o! the case; for il
is only requisite for US to be able tc
form in our minds some tangible idea
of the relative proportion which the
size OF even the highest mountain
bears TO that o! the entire globe itsel


TO convince US, if such a crust could
once form and support itself, that il
could with ease support the weight oi
the mountain also. The great Hima-
layan chain of mountains rises to i
maximum altitude of 81 $50 feet, or siN
miles above the level of the sea; and
if the earth could be seen reduced in
scale down TO the size of an orange, tC
all intents and purposes il would LOOK
like an almost smooth ball, since even


the highest mountains and deepest
valleys upon its surface would present
to the eye no greater inequalities ~
; outline than the little pimples and hoi
lows on the outside of the skin of al
ordinary orange. Ii this thin crust o


the earth can support itself, il is moi


at all likely to be crushed in by the
comparatively speaking, insignifican


weight of our greatest mountain
chains ;. for, in point of fact, it woulC


be quite as unreasonable to maintain
such a disposition, as to declare tha


the shell of a hens egg would be crush
ed in by simply laying piece OF
similar egg-shell upon its outside.


That very thin spheroidal crust, o.


shell, enclosing a body of liquid matter
, such as an ordinary fowls egg. doe


possess in itself an enormous degree o
stability aud power to resist pressur
from without, is easily demonstrates
by merely loading small portion o
its surface with weights, as long as
does not give way under them. Ever


when placed on its side (or least sronI


position), it is found that portion
the shell, only one quarter OF an mel


square. will sustain several pound


weight without showing any symp
toms Of either cracking or crushing
r or, in other words, this simple expert


ment indicates that IL the externa
crust of the earth were but as thlcl
: and strong in proportion as an egg


Shell, il would be fully capable OF sus
tanning masses, equal In volume an
! aud weight to many Himalayas. pile
: up one atop of another, without an.
E danger whatever to its stability. ~
tract from a Lecture by Ddrid foToe'


f. R. s.