The Norfolk Virginian. [volume] (Norfolk, Va.) 186?-189?, 1897-07-11
WHEN 'EHIE EARTH SHAKES.
austrian sciendints nro Trying TO Got
"n Average OF RIO W Ear it Moves.

- reHarkaDle series Of experiments Is
oelnE carried on by the Military Geo
aphlca Institute of Vienna, with a
view 20 determining the physical
changes which earthquakes cause on THE
suiIace or the earth. says the Philadel-
phia Press. It is the idea OF scientists
That popular fancy has ALWAYS very
much magni1ed the actual displace-
lnents caused by the ~upheayals. De-
scrlptions OF terrestrial qu1verlngs nave
nlaoe houses rock to and fro like the
sWaS1ng OF q ships masts, and trees
snap like the forests In the path Of a
sweeping cyclone. The terror of man Is
largely coincident with This conception
"a conception which seemingly no
amount OF experience can alter. Yet It
IS we'll known that In q very large num-
per OF destructive earthquakes the
movement. either lateral or vertical, Is
noI more and frequently less than an
men. although the general or communi-
cated expression may amount to an
enormous disturbance. This was the
case with the earthquake Of the Riviera
m 1856, and also with h upheaval
which In 1888 destroyed the town Of
Casamissiola, on the Island Of Ischia.
II 49, however. known that In some in
Suahces the movement has been much
more pronounced. and that permanent
displacements Of level of a few feet have
olloWed the seismic disturbance. In
order 70 bring positive facts to bear
upon this important question In terres-
trial physics, h Military Geographical
institute of Vienna has repeated a. num-
her of dwellings, in districts in Austria
which have been affected by earth
quakeS, and the region Of Agram. In
roatia is that which is now receiving
Ine attention Of the Austrian engineers.
me material is in the hands OF Lieuten-
ant Colonel Franz Lehrl, and the data
Snn orr " m 1SN - . 4 4 - 49, ---1 -
OF an extremely interesting nature.
Herr A. WeiXler, an assistant at the
institute. has worked out a comparison
or four trigonometricaaly fixed points In
me same region. obtained in the years
1916. 1898 n 1SS6-the towers Of the
ioomkirche and Ma~rkuskirche in Agram,
the tower of st. Martins church i'm the
village of Dugoselo. and a bcnch-mark
on the Sijemen Mountains, 3,4O0 feet
i'igh-and has found as the result Of his
dwellings values of horizontal displace-
ments ranging from IL to S.8 feet; the
height of II Domkirche, calculated
from the sea level, was In 1916, 1851 feet:
IN 1920. 1861 feet, and in 1856. 44o.9 feet.
Inc position for the present year is not
yet stated. These observations make
clear how little reliance can be placed,
through extended periods, on datum
marks OF earthquake-affected regions.
IN the earthquake districts OF Cen
tral America the constant %upheaving OF
the earth has brought about some GU
rious economic conditions. For in
stance. the gas and oil pipe lines have
to be fitted with what are known as
earthquake joints. The abutting ends
Of the lengths Of pipe are, so to speak,
slid past each other. That Is, one over
the other, with Il soft rubber ring sepa-
rating them. The arrangement is some
thing like that Of a telescope. When an
~upheaval occurs the pipe lines veers
UP and down or sidewIse. but the soft
rubber joint allows 1t to do so without
danger OF breaking. Some Of the minor
railway tracks are arranged in similar
order.