The aegis & intelligencer. [volume] (Bel Air, Md.) 1864-1923, 1881-09-02
miscellaneous.
The Interior of the Earth.

That the interior of the earth is the seat OF
intense heat is Il familiar truth. Volcano
phenomena give us ocular demonstration OF
it. Mining experiences, moreover, have fur.
nishcd us with an almost uniform rate al
which heat increases, and this is generally
computed to be about degree Fahrenheit
for every So feet of descent But mining ex.
perienccs are necessarily very limited. The
deepest mine in England, that of the Rose.
bridge Colliery near Wigan, takes us down
only g 4j feet and to temperature not much
exceeding 30 degrees Fahrenheit. 1t is hot
enough to make the work exceedingly irving
TO the miners, but that is ALL This, however
is $50 to speak, scarcely traversing the earth's
epldermis But five may assume n uniform
increase of heat in descending the tempera-
ture at depth of 80 miles may be eXprCsst d
in figures as 1900 degrees Fahrenheit. In
other words, at less than an eighth of the dis
lance which lies between the circumference
of the earth and its centre, the heat would be
about % times the heat of boiling water at
the sea level Proportionate figures might
ofcourse, express the heat at greater depths
still, but figures fail to convey any idea to the
mind of that which must necessarily trans
cend all Imagination. Suffice it to say, that
in descending series We must eventually
come to heat so great that no substances
with which We are acquainted could, under
any conditions which we can imagine, exist
i'll it in either solid or fluid form And we
conclude, therefore, that if the earlhs centre
be not itseltin gaseous condition and there is
reason to think that it may not be so, there
must be gaseous zone somewhere between a
solid centre and II solid circumference. "Fd-
CHS dcSceRSHs ArerRE' is proverbially treated
as Il trulsm But if the classic authors arc to
be our guides, and il in the centre of our
planets Achcrotian shades and Eysan fields
are to he localized, there will be found practi-
cal difficulties of access which might well
discourage even so substantial parsonage
rs ghost, Nor can the all-powerfu ina
gnaton accomplish the descent with any
approach to ease The distance we may SUP.
pose TO be nearly 1890 miles; but along
II line OF this length connecting the surface
OF the earth with its centre, we may safe.
~ assume that conditions would vary great
~, and (since heat and pressure have TO be
balanced one against the other probably by
no means uniformly. We can measure
the power of pressure upon the surface but
in the neither depths its power is in part open
to conjecture, nor can we say how soon we
may reach debatable zone, ut which the
responsiveness ofheat may overcome the COM
prcssive force of grayitation. Nor, again,
could we venture to expect to find that zone
itselfalways at a uniform depth. Here and
there it seems to approach the surface The
volcano is natures satety-valve and the
cavernous rumble of the earthquake warns
us that there are imprisoned gases beneath
our feet which pressure but imperfectly pre-
vents from escaping. Upon other ground,
also, it is quite evident that our experience,
limited as it is to the surface of the earth may
tend to mislead us in regard to what lies be-
meath the surface; for if pressure increased
uniformly with depth, the average density of
the earth would be much greater than what
upon astronomical data we know it to be-
The earth, as Il whole, is about five and a
half times as heavy as it would be if it were
entirely composed Of water; or, techni-
cally expressed the density Of water is one,
and the mean density of the globe is five and
half. But five and half is only about
double the density of rock matter upon the
surface; whereas, if nothing but steadily in
creasing pressure be supposed, it would vast
ly exceed this. There is, therefore, only one
possible explanation. Heat, intense heat,
somewhere or other, overcomes pressure and
converts everything into gas and if it were
in our power to try experiments, and to feed
the subterranean crucible with the most in.
tractable Observation-Disclosures fire proof
safes, or what we will-all would there share
the same fate--instant evanescence.- Belgra-
min