The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1902-05-25

l'dCCoHMcudLeu 10 the IdCl lndI the WEole
globe is lessening The circumference OF
our earth at the equator must be gradual
~ declining; certain length in that cir
conference is lost each year. We may
admit that loss to be a quantity far toe
small to be measured by and observations
as yet obtainable. but, nevertheless. is
productive of phenomena so important
that it cannot be overlooked.
1T follows from these considerations
that the rocks form the earth's crust
over the surface of the continents and
! the islands, or beneath the beds of the
oceans, must have lessening acreage
| year by year. These rocks must there
fore submit TO compression either con-
/ tinuously or from time TO time, and the
necessary yielding of the rocks will in
| general take place in those regions where
the materials of the earths crust happen
to have comparatively small powers of
resistance. The acts of compression will
often, and perhaps generally. not proceed
with uniformity but rather with small
| successive shifts, and even though the
dispIacements Of the rocks in these shifts
be actually very small, yet the pressures
to which the rocks are subjected are so
vast that a very small shift may CORE
spond to a very great terrestrial dis
| turbance.
Suppose, for instance, that there is a
slight shift in the rocks on each side
of a crack, or fault, at a depth of ten
miles. II must be remembered that the
pressure miles down would be about
thirty-hve tons TO the square inch. Even
slight displacement of one extensive
surface over another, the sides being
pressed together with a force of thirty
five tons on the square inch would be
an operation necessarily accompanied by
violence greatly exceeding that which we
expect from so small displacement if
the forces concerned had been only Of
more ordinary magnitude. On account of
this great multiplication of the intensity
of the phenomenon, merely a small rear
rangement of the rocks in the crust of
the earth in pursuance of the necessary
work of accommodating its volume to
the perpetual shrinkage. might produce
an excessively violent shock. extending
far and wide. The effect of such shock
would be propagated in the form of
waves through the globe, just as vio-
lent blow given at one end of a bar of
iron by hammer is propagated through
the bar in the form of waves. When the
effect of this internal adjustment reaches
the earths surface. II VIII sometimes
he great enough to be perceptible in the
shaking it gives that surface. The shak-
ing may be so violent that buildings may
not be able 10 Withstand it. Such is the
phenomenon of earthquake
when our earth is shaken by one of
those occasional adjustments of the crust
which I have described, the wave that
spreads ike a pulsation from the center
of agitation extends all over "the globe
and is transmitted right through it. At
the surface lying Immediately over the
center of disturbance there will be a
VIOLENT shock. In the surrounding coun-
try. and often over great distances the
earthquake may also be powerful enough
10 produced destructive effects. The con-
vulsions may also be manifested over a
Tar larger area of country in a way
which makes the shock to be felt though
the damage wrought by it may be inap-
preciable. But beyond limited distance
from the center OF the agitation the
earthquake will produce no destructive
effects upon buildings. and will not even
able 10 the ordinary observation.
In each locality in which earthquakes
are chronic it would seem as If there
must be some particularly weak spot in
the earth some miles below the surface.
a shrinkage of ths, earth, in the course Of
the incessant adjustment between the in
terror and the exterior viii take place
by little occasional jumps at this particu-
lar center. The fact that there is this
weak spot at which small adjustments
are possible may provide. as it were.
Il safety-valye for other purposes in the
same part Of the world. Instead Of a
general shrinking. the materials would
be sufficiently feNsole and elastic 10 al
low the shrinking for a very large area
10 be done at this particular locality.
In this way We may explain the fact
that immense tracts on the earth are
practically free from earthquakes of a
serious character while IN the less fortu-
nate regions the earthquakes are more OF
less perennial.
Now. suppose an earthquake takes
place at Japan, II originates a series %
vibrations through our globe. We must
here distinguish between the rocks-I
might almost sav the comparatively t:iaat
rocks-which form the earths crust and
those which form the intensely rigid
core or the interior Of our globe The
vibrations which carry the tidings y
the earthquake spread through the rocks
on the surface. from the center OF the
disturbance. in gradually charging cir
oies we may liken the spread q these
vibrations 20 the rippleS In a pool ot
water which diverge from the spot
where O raindrop has fallen. The
vibrations transmitted By The rocks on
the surface. OF on the floor OF the ocean. /
VIII carry the message ali over the earth
As these rocks are flexible. Al all events
bY comparison with the eaTth's interior. /
the vibrations viii be corresrondsnciv
large. ard VIII travel wiki vigor ever
land and under sea IN due time they
reach Say the Isle 81 Wight. where they
set the pencil OF the seis-nometer at WORK
But there are different ways round The
earth from Japan 10 the isis II Wight. +
the most direct route being across Asia !
and Europe. and the route across the
Pacific. America. and the Atlantic. The
vibrations VII travel By both routes. and
the former Is the shorter Of the Two.