Juniata sentinel and Republican. [volume] (Mifflintown, Juniata County, Pa.) 1873-1955, 1884-09-17
0hy tho Earth 0uaKes.

Prof Nerriman. OF New Brunswick,
saws: ssWhile facts enough regaruinS
the extent of the earthquake OF tie ou
of An1nst have not come to hand 70
enable ME to speak on the dlrectlon %
the earth wave or its peculiar ledtuie'
as compared with other earthq quaAes,
vet something may be said as 70 lne
latest convictions of students OF science
ON the nature of the earth below tne
point any man can penetrate: iuae
NAV lead us to guess intelligently at 'he
cause of earthquakes.
.'You know the long received theory
of the nature of the interior OF Tie
earth was that it is molten mass anu
that we move around on crust enVei-
oping the earth and caused by the cool
ing off of this mass on the OUTSIDE. IL
is undoubtedly true that about ~ miles
below the earth's surface the tempera-
ture is SO high that everything IS III
melted condition. We know this, De-
cause we have learned that every hity
feet we penetrate into the earth there Is
an increase OF temperature OF about
deg. and at distance of thirty miles
the heat is so great that any substance
we know of would melt. Perhaps the
melted mass is in the form OF a Iquld-
That would be certain but Tor the I'M
nense pressure on it. The pressure is
estimated at IL, 900 tons on a square
foot. OF course scientific men cannot
experiment with matter at a hlgh
temperature with a pressure OF lO,VOO
tons to a square foot, so we can only
guess what may be its condition. In
talking about this melted mass thirty
miles under us the term watery SUD-
stance is used by geologists.
''How great IS the distance through
this water substance we do not know,
but it is certain that its density increas-
es more and more, gradually, until the
interior of the earth is solid probably,
from the inconceivable pressure 1000
600 or 5000 miles from the surface
Sir William Thompson has demonstra-
ted that the earth must have core
much denser than the land and water
we live on. He points out the fact that
if shell only thirty miles thick sur
rounded a molten liquid mass extend
ing from one side of the earth through
the centre to the other side, then the
moon through the law of grayitatlcn.
would displace the liquid or gas in the
| interior of the earth to such an extent
that the earth's crust would bulge out
in the direction of the moon, making
tide in the solid crust of the earth, as
certainly as the skin or an orange
bulges out when you squeeze the fruit
between the palms of your hands. And
/ this would be evident to us because the
ocean tides would be almost, If not
quite. mperceptible to us. To with
stand the attraction of the moon, the
earth, Sir William says, must be as
ngld as steel.
80 we have the theory that the
crust of the earth floats on and imposes
an immense weight on water SUBJ
stance, which is inconcelvably hot.
| Now as to the way an earthquake may
he caused. Suppose moisture trlekled
gradually, year by year, through this
crust into the heated mass. In our
atmosphere steam would be produced.
| Thirty miles below US the pressure IS
SD great that it is not likely that steam
could be generated. One thing,
though; the pressure of 10000 tons To
the square foot, a pressure exerted III
every direction, would be increased.
Some effect must be produced down
there, and it is easy to see that If one
place in the esrth's crust Is weaker
than another near the region where tine
water trickled in, then 1.-THE weakest
place must STAN the strain" 1t Is moi
unreasonable To suppose that this pres
sure below might be so great that the
earth's covering was shifted little t.
adapt itself to the pressure from below.
This shifting of the crust Is, in fact,
the earthquake. l believe this theory
has the greater reason on its side, be
cause earthquakes are almost always IL
the regions of volcanoes, and volcanoe:
are always in or near the ocean. An
other theory of earthquakes Is that a'
the earth is very gradually cooling of
the crust Is thickening on tine under
side, and cracks or assures on the und'
side of the crust many miles deep MAJ
occur in consequence of the enormous
pressure, 50 that the water substant'
rushes into a new position with fore
that would knock continent out o
shape if it took place on the earth
surface. That motion would be sutti
cient to produce a vibration 30 mile
distant.