Maryland independent. [volume] (Port Tobacco, Md.) 1874-current, 1886-09-10
The Study of Earthquakes

The Geological survey, in pursuIhce
Of the purpose of its director to MAKE a
thorough study of the phenomena d the
earthquake ofAugust 81. has prepared a
circular to be sent to all parts Of the
affected area and the adjacent country,
calling for detailed information upon the
subject from whomsoever may have in
fomatlon even Of an apparently trivial
character to impart.
The observer is requested to state bis
own position, whether in doors or out,
upstairs or down; whether standing,
walking or sitting, and to describe the
ground of his locality, whether rocky,
earthly or sandy.
Hardly any fact, however apparently
insignificant, regarding this great earth
quake will come amiss, and it is probable
that from the mass of information to be
gathered data of great scientific value
will be deduced. 1t is requested that
this information shall be sent to the d.
vision Of vote mic geology, Geological
Survey. 1t is probable that before the
end of the year elaborate, though neCes-
sarily rather inexpensive, arrangements
for the more thorough observation and
study of seismic phenomena occurring IN
all parts of this continent will be per-
fectcd and set in operation. These ar
engagements have been in progress kor a
year or more. and the most adv I'd
students Of this branch of natural se'esce
are interesting themselves in the work
Instruments of great delicacy, though
simple in their principles of construction
and operation, have long been IN use
for automatically recording earth move
ments. Perhaps the best has Tor Its
central feature a disc of smoked glass re-
volvtd horizontically by clock work
Besides this are hOrizontical pendulc
delicately suspended upon pivots, and
carrying weights of sufficient inertia tt
keep their pendula at rest, tholgh th'
stands TO which they are attached b'
moved Each pendulum bears at it
xfremity pointer, which, being draw
over the SUI oked disc as the latter revOl
YES. marks a true circle so long as lht
e,rth remains unmoved, but with tht
slightest movement their course is dis
turbed and their record is seen IN waving
or tagged lines around the disc. IW'
Of tboso nendnlo are required for elcl
selsmograph one recording the east au'
west movements, and the other thoS'
north and south. This instrument Is to-
delicate and complex for use outside o
the observatories and laboratories "aer'
il can have the attention OF TRAINED
observers But another and mucn SIN
pier device has nearly been perfected
which it is proposed, shall be placed ii
the hands of volun Ger observers ~ many
parts of the country. 1t consists Of ;
vertical pendulum, whose point hang
over a cup of mercury, upon the surface
of which lies platinum float a SINAI
depression in the Goat receives the pom
without making actuall cotrac'' eAeeP
when the mercury is disturbed 10 wllcl
event the contact will be made, cohpiet
ing an electrical circuit, when By
Withdrawing detent, sets ID mo''Ou ta'
machinery of an ordinary CLOCK i
proposed that only one or two nuuaref
Of these instruments shall be Sent out a
r.osant Thosa will record only the be-
ginning of the earthquake Du. 'ael
will serve also the purpose OF eailing al
tention to the disturbance "nicn nlg9
otherwise escape notice, and thus enable