Year: 1871

is molten sphere, surrounded by thin
crust of solid matter, was once almost uni
versally taught by biologists, there have
of late years bee-l brought forward several
arguments to the contrary, which, ap-
parently, are more in favor of its being
solid, or f,arly solid mass throughout; and
these arrxuments are fully entitled to our
conslc c4eration, as our object is not to de-
fenra any particular theory, but to arrive,
rs nearly as we can, at the truth. I will,
hereafter, in the first place, proceed to
scrutinize all which has been brought for
ward in opposition to the older hypothesis,
and then to consider whether any other
explanation vet advanced is more in &C.
cordance with the facts of the case.


First of all, we are to answer the ques-
ton as to whether it is possible for such
thin crust to remain solid, and not at once
to become melted up and absorbed into the
much greater mass of molten matter be-
meath it? 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,
however, in reality answers itself in the
negative, since it is evident that no crust
could even commence to form on the sur
face, unless the sphere itself was at the
moment actually giving off more heat, from
its outer surface to the surrounding atmos-
phere, than it could supply from its more
central parts, in order to keep the whole
in a perfectly fluid condition; SO 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
OF re-absorbed into the fluid mass below.


nxknv nf cC1I ion
due to refrigeration, would then continue
going on from the outside inwards, until
thickness of crust had been attained
sufficient to arrest, or neutralize lowing to
its bad conductibility of heat) both the
cooling action of the surrounding air and
the loss of more heat from the molten mass
within and thus stage would soon be
arrived at when both these actions would
80 counter balance 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 depend 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 earth's exterior were in reality
only such thin covering, or crust, like
the shell of an egg, to which it has often
been Ekened, 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 Hima-
layas of Asia, or the Andes of America,
which are, as it were, masses 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. It requires but little sober
consideration, however, to prove that it is
rather, so to speak, sensational 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 minds some tangible
idea of the relative proportion which the
size of even the highest mountain
bears to that of the entire globe itself,
that it could with ease support the weight
of the mountains also. The great Himal-
ayan chain of mountains rises to a maxi
mum altitude of 81 $50 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 noun
tains and deepest valleys upon its surface
would present to the eye no greater in
equalities 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, insig-
nifcant weight of our greatest mountain
chains; for, in point of fact, it would be
quite as unreasonable to maintain such q
disposition, as to declare that the shell OF
hens egg would be crushed in by simply
laying a piece Of similar egg-shell upon
its outside


That very thin spheroidal crust, OF
shell, enclosing body of liquid matter
such as an ordinary fowls egg, does pos
cess in itself an enormous degree of stabil.
ity and power to resist pressure from with
out, is easily demonstrated by merely load
ing small portion of its surface with
weights, as long as it does not give way
under them. Even when placed on its
side (or least strong position) it is found
that portion of the shell, only one quar-
ter of an inch square, will sustain several
pounds weight without showing any
symptoms of either cracking or crushing
or, in other words, this simple experiment
indicates that if the external crust of the
earth We're but as thick and strong in pro.
portion as an egg-shell, it would be fully
capable OF sustaining masses, equal il
volume and weight to many Himalayas
piled up one atop of another, without any
danger whatever to its stability. Ertrac
from a Lecture by D00id Forbes, r. r. S


TIE FIGURE F1vE.-Any number O
figures you may wish to multiply by


will give the same result if divided by 2
much quicker operation; but you mus
remember to annex cipher to the answer
when there is no remainder; and whel
there is remainder, annex a to tn
answer. Multiply 464 by 5, and the answe
will be 1890; divide the same number b.
2, and you have 232, and, as there is no re
mainder, you add a cipher. Now talk
347, and multiply by 5, the answer is ], ,785
On dividing 357 by 2, there is 17S, and
remainder; you then place at the ent
OF the result, which gives 1,785. TIL,
reason of this process is obvious, sine


multiplying by is the same as multiply
ing by 10 (which is effected by placing
cipher to the right of the units place) an,
dividing by 2.


THE head-letter of the Greeley (Col.


Tribune is a fac sSnss7e of the hand -writin


Of the great agriculturist, after whom tn