The Hawaiian gazette., 1912-07-09
Earthquake Rings a Bell and
Starts Machine to Working
Scientists at KiIauca installing instruments
at Observatory Records to Be Made
Of Every Earth Culver.

minute fitting of the earth surface in
its neighborhood.
The second type of instrument con.
sists of two horizontal pendulums of
less weight and smaller dimensions
correspondingly less sensitive - de
signed for the registration of weak
or moderate shocks, local in origin or
emanating from moderate distance on
~. These are mounted to register E-W
and Ms components of motion.
Continuous Records.
Both these types register continuous
ly on smoked paper bands wound and
fastened on revolving drums which also
are slowly carried sidewise by screw
cut on the axles. Once each minute an
electromagnetic operated by the brief
closing of an electric circuit makes a
time mark on the revolving record. Con-
sequently these seismographs make per-
manent record of the time, character
and amount of all earth vibrations or
warnings to which they are sufficiently
sensitive.
Earthquake Recorder.
The third type of instrument is de-
signed for the registration of ''ordi-
nary earthquakes that is, moderately
strong shocks of local origin. 1t con
sists essentially of two lightweight
horizontal pendulums capable of small
magnifcation of the earth motion, SET
to measure S-W and Ms components
together with light, vertical pendu
lum Ga small weight at the end of &
short lever kept " floating" in air by
two balanced spiral springs) to measure
with small magnifcation the component
of earth motion in the up-and-down di
rection. This instrument further diff
fers from the others in that it writes
no record except at the time of suf
fciently strong shock.
Shock Starts Machinery.
These pendulums write upon smok
ed paper band wound on drum whicl
is set revolving rapidly by the releas
of its driving clock at the instant whel
the earth motion becomes great enoug
to disturb sufficiently sensitive start
ing device which closes an electric eli
cult thereby operating the necessar
electromagnetic. Because of the rapi
motion of the drum chronographi
mechanism is provided which mark
, half.second intervals on the moving ret
ord. The time of starting of the rec
!, ord is printed on the dial of the sts
> ton clock by an ingenious movement
of the dial itself, also actuated by a
, electro magnetic device. An alarm be
! may also be set ringing when the star
: ing mechanism is disturbed. Becaus
! of the great delicacy and sensitivenei
Y of these instruments to vibrations an
= to warnings in the rock basement,
changes of temperature and to curren
in the surrounding air, it is clear tn;
! their complete adjustment requires tin
:. and patience. After setting up the
J. need to "settle' to bring their vario,
!. parts into mechanical adjustment to IL
static strains which act on them. The
It for their registration to be of mo
n value the periods and magnification ia
t tors of all the instruments need to
d adjusted so as to be approximate
e equal, or equivalent, to each other al
q to the standards adopted in other sci
Q mographic stations. This Cunning up
requires time and several weeks W
probably elapse before the work of I'll
seismographic station can come upon
o. routine basis. Very respectfully,
t. II. o. WOOD, Associate.