The Republican. [volume] (Oakland, Md.) 1877-current, 1885-04-11


an effect similar to that which follows
when vessel strikes a sunken rock or
runs aground.
But whilst earthquakes may thus
i. seem to happen without the slightest
warning, there can be but little doubt
that their apparent suddenness is due
either to want of observation or to a
wilful disregard of the signs which indi-
cate the advent of subterranean out
bursts. Their approoch is usually her
| aided in many ways-underground
noises, gaseous emanations from the
| soil, the drying up of wells, a change in
| the temperature of thermal springs,
haziness in the air, being the more gen.
eral forerunners of these phenomena.
| At such periods. too, a sense of dizzi-
ness is often experienced by jewellers in
| the threatened locality, whilst microcos-
mical instruments, if there be any in
the district, will register slight varia-
| tons of subterranean activity. During
| the continuance of the earthquake the
ground often heaves like the sea, pro-
ducing feelings akin to the familiar
| pangs of sea-sickness; rivers seek fresh
channels; large assures open in the
earth, and permanent changes take
place in the geographical features of the
| country. Thus the series of earth
quakes which in 1926 and 1927 visited
| New Zealand. caused so distinct Il
| change that the former features of the
coast could be no longer recognized.
The earthquakes of the present century
in Chill have produced a permanent
| plnvotiAn of tho tbarn. and 70
cent subterranean outburts in Java
have considerably modified the geo
graphy of that region.
Concerning the origin of these phe-
nomena, so far-reaching in their effects,
it must be admitted that the true theory
has never yet been framed. Early spec
ulations were much tinged with the SUI
perstitions of the time; and even so
late as the beginning of the present
| century we find lingering remnant of
this superstitious regard of physical
phenomena in the naming, by the in
habtants of Sindree, of a mound
thrown up during the Indus earthquake,
"Ullah Bund," or the Mound of God.
1t is obvious that the study of these
interesting phenomena is beset with
many difficulties. Observation can
| often only be made at imminent per-
sonal risk. Yet, spite of this begin
ming with the few observers and the al
most mythical records of the days of
Pliny, the fascinating subject has con-
tinued to attract an ever increasing
circle of students. who have ever more
earnestly underworld to pierce the veil
Of mystery which surrounds it. Each
fresh manifestation of subterranean en-
Crgy is now watched with increased in
terest Whenever possible, the Sc
quence Of events is noted with extreme
detail old theories become weakened.
fresh ideas confirmed, and new avenues.
of thought open themselves to the earn
est investigator at every step.
With tie phenomena of earthquakes,
those of volcanoes are closely linked,
volcanic outbursts being frequently her
aided and accompanied by earthquake
shocks; and there can be little doubt
that the two are most intimately bound
up, if, indeed, they are not two effects
arising from a single cause. This being
so, the facts which surround the one
class of phenomena may be drawn upon
in attempting to frame an explanation
whence and how either originates
That some portions of the earth's inte-
riOr are in an immensely heated con-
dition, the pature of the materials
elected from volcanic vents renders ev-
dent, and observation has also clearly
demonstrated the fact that the temper
allure increases from the surface of the
earth doWnwards, the average increase
being one degree Fahrenheit for every
fifty feet OF descent. Now, from core
sideratlOns connected with the figure of
the earth and the other members of the
system to which it belongs, it has, with
much probability, been inferred that the
solar system has evolved from one Of
those glowing gaseous aggregations
termed nebulH. that this world was
once fluid haze of light" and that
when it first existed as in independent
vent heat, a residue of which now gives
rise to volcanic phenomena.
What happened, then, as our earth
radiated its primitive heat into space?
The question is a veXed one. So many
men, so many minds. One class of
theorists, not giving sufficient weight to
the fact that the increase of pressure
towards the EARTH center would tend
to keep matter solid there under the in
lluence of high temperatures, suppose
that the process of radiation by the
earth into space has, throughout the
lapse of ages, resulted in the formation
of solid external crust covering a still
fluid nucl us. But this class of theorists
is, like the volcanoes of Britain, practi-
cally extinct. or is at least as subdued
and unpretcnding as the Suffolk earth
quake. Other biologists, giving more
weight to the fact Of increase of press
ure towards the earth's center consider
that its condition is that of Il body with
a solid nucleus and solid external
crust, between which there still re-
mains a residue of liquid matter.
In objection to both these views it has
been shown that for the earth to maintain
its rigidity under the moons attraction,
such Il crust must be OF enormous thick
ness, of so great thickness, indeed,
that Sir William Thomson, who investi-
gated the matter, prefers to consider
the earth as a solid globe cooling by
contraction. On this view of the earth $