Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-01-21

is thus possible that these great natural cat
aclysms have a definite effecton the men
tai and moral nature of the inhabitants.
A study of various seismograph records
shows that an earthquake always manifests
itself as a vibration, partly horizontal and
partly vertical. The ratio of the dis
placement averages about six to one.
The extent of the movement is surprising
1y small Thus a horizontal vibration,
when the displacement amounts to a
tenth of an inch, is easily noticeable.
If it reaches half an inch, it is dangerous,
while if it reaches an inch, shattered
chimneys and walls are sure to result.
In several earthquakes the motion may
perhaps equal foot. These distances
are all measured at the level of the sur
face of the ground. At the tops of build
ngs the amount of motion is greatly in
creased. | myself have seen the iron
cross on a church spire swing through a
range that was estimated at about six
inches, and yet the shock was not a severe
one, little damage being done.
The speed with which earthquakes are
transmitted varies greatly, depending
chiefly on the character of the soil, but
also somewhat on the intensity of the
shock, violent earthquake being trans
mitted at a somewhat higher speed than
a mild one. The velocities actually OBJ
served in different cases range all the way
from about a mile to nearly ten miles a
second. The latter figure was derived
from observations made between Chile
and Japan and should be somewhat re-
duced if it is the fact, as appears to be,
that the shock is actually transmitted
through, instead of around, the world.
Although transmission through the
earth seems to be possible, it is yet clear
that earthquakes never originate near
its center; otherwise they would some
times be felt on the opposite sides at
nearly the same time. Similarly we
find that they never originate at great
depths, such as five hundred or one thou
sand miles. 1t is improbable that the
depth of the origin ever exceeds thirty
miles. In certain cases it is more likely to
be at depth of only few thousand feet.
We now come to a curious class of
observations, when bodies, such, for
instance, as lamps, are projected YER
tically out of their sockets After the
SISdS PcliiCoC Sol CiiClI vi lo9l IL
was found that certain large gate-posts
had shifted their positions by a series of
jumps, each jump measuring from one
to four feet The original position of the
gate-posts was well marked, as were also
the impressions on the ground where they
had temporarily landed. Perhaps the
most surprising statement of this sort we
have on no less an authority than that of
Humboldt, who tells us that during the
great earthquake of Riobamba, Ecuador,
in 1907, bodies were projected verti-
cally one hundred feet into the air.
This statement probably refers to sand
and mud, which together with hot water
and gases are sometimes expelled from
earthquake cracks as from a volcanic
crater. The sulphuretted hydrogen
emitted at such times from the bottom
of the harbor of Callao Peru, is occa-
sionally sufficient to blacken the white
paint of the shipping. This phenome-
non is locally known as ''the painter" 1t
is said that in some earthquakes such as at
Lisbon flames have risen from the ground
Several Investigators have endeav-
ored to find some relation between earth