The Rugby gazette and east Tennessee news. (Rugby, Morgan Co., Tenn.) 1884-188?, 1885-03-07
EARTHQUAKES.
khe Theories of Scientific Men and Sells
mologists in ltegard to Them.


Rho Theories of Scientific Men and seis-
biologists in ltegard to Them.
The intimate relation between earth
quakes and volcanoes is universally I'd
mjtted, though earthquakes do occur in
regions which give no indications OF
either past or present volcanic activity.
Along the southeast coast of Spain,
however, there is ample evidence of
such activity in past times; and has
been remarked by a writer on the sub
ject that an earthquake is simply an in
tegrated volcano. As to what, how
eyer, is the exact cause of chronological
action biologists have not yet made up
their minds. The mathematiclans have
compelled them to give up as quite I'M
tenable the old idea of thin crust over
molten interior which in its sGrgings.
would break through in the shape of
volcano, or reproduce in the shell the
huge waves which would swell along
the internal surface. The hypothesis Of
solid shell and solid nucleus with
molten matter between has Jared little
better. The earth, it X now held by
the best biologists and physicists, must
be solid body to very considerable
depth, if not, indeed, to the core. At
the same time we may be assured that
the most intense heat exists at no very
great depth below the surface, heat so
great that but for the immense pressure
eXerted by the superintendent mass the
matter would actually melt; it is held
that it does occasionally do SO when
from any of the many forces which are
at work the pressure is relieved, and
this, according to a certain school,
gives rise to volcanic or earthquake
phenomena:
Others, however, maintain that these
manifestations can be satisfactorily ac-
counted for by chemical and mechani-
cal action. 1t seems to be generally
admitted that great masses of water are
constantly filtering into the depths OF
the earth from the ocean bed; and that
the molten materials which issue from
volcanic rents have absorbed enormous
quantities of steam and other gases,
Prof. Judd tells us, we have the most
indisputable evidence. 1T is to the
violent escape of these gases from the
molten rock masses. as the pressure
upon them is relieved, that nearly all
! the active phenomena of volcanoes must
be referred" And what accounts fol
. volcanic action may also account for al
least a. certain class of earthquakes.
For there may be other causes, most Of
them, however, referrable to the move.
ments which must be almost constantly
;aking place in the interior, owing tc
the cooling of the earth's crust. Varia.
tions in atmospheric pressure have beer
thought to account for some earth.
quakes, and it is noticeable that SHARP
fall of the barometer was observed all
over the south of Spain in the afternoon
before the first great shock, and that
there have since been frequent fluctila-
TONS The mere falling of an internal
cavity would almost certainly produce
yibratory phenomena. Indeed Prof
Milne seems to believe that the earth is
full of cavities of all sizes, like huge
Gruyere cheese, and that consequently
vibrations of greater or less intensity
are constantly occurring, as we should
find had we instruments delicate enough
to measure them. But it is possible
perhaps, to have seismographs of mucl
too fine structure, so fine as to recorC
the vibration of every passing jinriksha
!. Essentially the explanation of all thes,
phenomena seems to be that our plane
is cooling body, and they will onl.
cease when every particle of heat ha
left the heart of our old mother, whel
" also, biologists tell us, there will be Mt
more sea, when the air itself will hav'
vanished, and the earth will be as deat
as the moOn.-LondOn Times