Worcester daily spy. [volume] (Worcester [Mass.]) 1850-1888, 1872-01-18

neutralize lowing 70 its bad conductibity of
heat both the cooling action OF the surrounding
air and the loss of more heat from the molten
mass within; and thus a stage would soon be
arrived at when both these actions would so
counterbalance one 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 minute
amount of heat from the Interior appears TO de-
pend entirely, as regards its temperature, upon
The heat which it receives from the suns rays.
We have next to consider the argument that
If the earths exterior were in reality only such
Il thin covering or crust, like the shell of an EGG
TO which it 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 it could never
sustain the enormous weight of its mountain
ranges such as, for example, the Himalayas of
Asia, or the Andes of America, which are as it
were, m :sses OF rock piled up high above its
mean surface level.
At first sight this style of reasoning not only
appears plausible, but even seems to threaten to
upset the entire hypothesis altogether. 1t re-
qureS but little sober consideration, however
TO prove that it is rather, to speak, sensation
nj in character than actually founded on the
facts of the case; for it is only requisite for us
to be able TO form in our own minds some tang-
bile idea OF the relative proportion which the
size of even the highest mountain bears TO that
of the entire globe itself, to convince us if such
crust could once folm and support itself,
that it could with ease support the weight of
the mountain also.
The great Himalayan chain Of mountains
rises to a maximum altitude of 81 800 feet, or
six miles above the level Of the sea; and if the
earth could be seen reduced in scale down to the
size of an orange, to all intents and purposes
it 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 in outline than the little
pimples and hollOWs on the outside of the skin
of an ordinary orange. If this thin crust of the
earth can support itself, it is not at all likely to
be crushed in by the, comparatively speaking,
insignificant weight of our greatest mountain
chanS for, in point of fact, it would be quite as
unreasonable TO maintain such disposition, as
to declare that the shell Of a hens egg would be
crushed in by simply LAYING piece Of a similar
egg shell upon its outside.
That very thin spheroidal crust or shell,
enclosing a body of liq lid matter, such as an
ordinary fowls egg, does possess in itself an
enormous degree Of stability aud power to re-
siSt pressure from without, is easily demonstrate
ed by merely loading a small portion of its sur
face with weights as long as it does not give
way under them. Even when placed on its
side Tor weakest posiiiOn) it is found that pOr-
ton of the shell, only One-quarter of an inch
square, will sustain several pounds weight
without showing any symptoms of either crack
ing or crushing; or, in other words, this simple
experiment indicates that if the external crust
of the earth were but as thick and strong in
proportion as an egg shell, it would be fully ca
pahle of sustaining masses, equal in volume
and weight to many Hlmalayas, piled up one
ATOP another, without any danger whatever to
its Stabitv.-Ertrdct. from a Lecture by DdUid
Forbes, T. r. S.