Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1884-08-13


time L h said to have taken plaec was out
walking. That, Of course. does not contra
dict The statement Of those who say they
did feel ~
Chow can you account for the earth
why, simply by part Of the earth giving
away"
"some scientists attribute IL TO unusual
changes on the surface Of the sum-"
utter nonsense" was the reply.
"Changes OF sun-sposs undoubtedly have
an effect on the earth. They are apt 10
cause severe hurricanes, or TO twist the
magnetic needles about, but they wouldn't
bring on an earthquake"
"what does cause an esrthquakef"
.Tbe only common-sense explanation 10
INV mind ia that down In the bowels Of the
earth. say from twenty 10 one hundred
miles beneath the surface, there u fluid
matter. which, gradually becoming cooled,
contracts. leaving space between 1t and
The solid parts. Heavy weights on the
earth's surface above the spot arc apt 10
cause the surface 10 sink, and there you
have the earthquake. No; the sun.spots
didn't have ANYTHING to do with IL; you
can rest assured Of that"
PROFESSOR WILLIAM HARDNESS.
Professor William Hardness, Of the
United States Naval Observatory, in an
swer TO questions respecting bis views on
earthquakes and their relations TO the ply
sizes Of the globe, said: "In attempting 10
account for earthquakes II is first OF all ne
cessary TO have a knowledge, or at least
well-deiined theory, OF the internal struc-
turc OF the earth. And here, at the out
set, astronomers and physicists on the one
hand and biologists on the other differ
widely. The biologists assume that the
earth was originally In molten condition,
and that In the course OF ages solid crust
has formed on the outside, leaving a molten
interior. And further, from the numerous
fossil remains found imbedded In the rocks,
IL ~ inferred that uncounted millions oil
years have been consumed In the process.
The asti onomer aud physicist starts from
entirely different premises. lie weighs the
entire amouat OF matter In the sun
and planets composing the whole solar
system. then imagines il all converted into
gas aud cngendeied into nebulous cloud,
filing all space. Then, by mathematical
processes. he is able TO compute the total
amount OF heat which would be generated
by the condensation OF this nebulous mass
into body the size OF the sun, and dividing
this quantity by the total amount OF heat
emitted by the sun in twenty-four hours,
an approximation to the entire possible
duration OF the solar system IL obtained.
The conclusion arrived at Is that IL IL I'M
likely that the solar system has existed in
its present condition for more than twenty
five million years, and it seems impossible
that il can have existed So long as fifty
millions OF years, which, as the geologists
reckon time, is but an instant.
A SOLID EARTH.
"Until recently II was universally sup
posed by all scientific men that the interior
Of the earth is in a molten condition. But
the application Of more refined analysis to
the mathematical discussion OF the tides
has shown that this view is untenable. II
we suppose the hemisphere OF the earth
which al any moment is turned toward the
sun TO be covered with grass. and each
blade OF the grass TO be transformed into
an iron telegraph-wire attached to the sun,
the entire tension which all those wires
could support would be about equal 10 the
attractive force OF the sun upon the
earth. When exposed TO such an over
whelming force as this anybody not
extremely rigid would be pulled out
Of shape, and instead OF remaining
sphere would be converted into spheroid.
WITH ltS thic pOihtiiIE W bht Suus II
this were TO happen in the case Of the earth
ii would obliterate the tide, and the fact
that the tides are not obliterated. but have
nearly their exact theoretical height, proves
beyond question that the earth il not sensi-
bly, deiormed by The suns attraction. and
shows that the average rigidity OF the earth
is not very different from what ii would he
il the earth were a globe OF solid steel.
Under such circumstances it is difficult to
believe that the interior Is plastic or. that
volcanoes are more than local phenomena.
Earthquakes are phenomena OF wave mo-
ton. and il may be well TO recall the fact
that there are two very different kinds Of
wave.
TUE WAVE THEORY.
III dozen billiard-bals are laid in
row touching each other and one extremity
Of the series is sharply struck the ball at
the other extremity will be driven away,
while all the remaining balls will move
scarcely at all. When the first ball was
struck II was deformed and instantly eX-
plndiDe 10 resume IFS original shape.
Without moving itself IL transferred IT'S mo-
ton 10 the next bah Of the series, and SO on
till the last bali was reached, when, there
being 10 other ball 10 receive its motion, it
was Itself driven away. Here we have
wave OF condensation transmitted longitu-
dnally from ball 10 ball. The waves in
water are Of the other kind, the motion OF
the particles being vertical instead Of lougi-
tudinal, as is made evident by the IA
mlliar fact that any light floating body
simply hobs up and down upon the waves,
with little or no forward motion. An
earthquake wave is Of the first kind. That
is, il is mainly wave Of condensation.
i-,,o 20 no al % ~
quakes, but they are doubtless due to con-
cusions OF some kind or other taking place
in q very great depth below the surface OF
the ground. II has been suggested that
they may sometimes be due TO the falling
in Of subterTanean cayerns produced by
the action of wafer disSolying extensive
deposits Of rock salt, limestone, gypsum,
or other similar materials. 1t has also been
supposed that they may sometimes be due
TO the rupture Of rock masses in the int
rior 81 the earth, perhaps aided by the in
lection OF volcanic materials thrown into
the creyices thus produced.
OTHER THEORIES.
"Anoiher theory that has had great vogue
Is ibat they are due TO the crushing Of
rock masses by the contraction OF the earth
Us it continues TO cool. But this assumes
that the whole interior OF the earth is heat
ed. which we have already seen 10 be
questionable hypothesis, Although il seems
rash TO say that earthquakes are dependent
upon volcanic action, il is nevertheless
clear that both earthquakes and volcanoes
are due to some common cause, and rs the
great earthquake regions and the great vol
canic regions are nearly coincident with
each other, and almost without exception
in the neighborhood Of the sea, there seems
some reason TO suppose that steam gene
rated at considerable depths by the inter-
nal heat OF the earth may play prominent
part In the phenomena.
vELOCITIEs.
Gas 10 earthquake waves. careful obser-
yations show that they are 'propagated
through the crust OF the earth with veloci-
ties which depend upon the geological for
nation OF the region in which they occur,
and which range from eight hundred 10
eighteen hundred feet per second, but the
greatest velocity OF the earth-particles
themselves scarcely ever exceed fifteen
feet per second, and even in shocks
severe enough TO demolish heavy ma
sorry the range OF motion is proba-
bly, not more than two and half
inches. When we remember the care with
which the recent earthquake at Ischa. In
the Bay OF Naples, has been studied by
scientific mer, and the trining amount Of
exact information respecting its cause
which has resulted, the futility Of attempt