St. Paul daily globe. [volume] (Saint Paul, Minn.) 1884-1896, 1886-09-06
MAKING CALCULATIONS.
The Geological Survey Wants Inf0r-
ma ton en- the Earth0 uake


nation ON the Earthqu ake.
WASHINGTON, Sept 5.-The geological
survey, in pursuance of the purpose of its
director to make thorough study of the
phenomena Of the earthquake of Aug. 81,
has prepared circular to be sent to all
parts of the afflicted area and the adjacent
country, calling for detailed information
upon the subject from whomsoever may
have information, even of an apparently
trivial character. The observer is re-
quested first to state his own position,
whether indoors or out up stairs or down,
whether standing, walking or sitting. and
to describe the ground of his locality,
whether rocky earthly or sandy. Follow
ing this it is desired that series of ques-
lions, in substance as follows, shall be an
swered categorically:
First-WSs an earthquake felt at you place
the evening of Aug. 81, or within few days
of that time? Negative answers to this will
be of great interest from any points within
the disturbed area, and especially from points
near its limit.
Second-At what hour, minute and second
of standard time was it felt?
Third-How long did its pereeptible motion
continue?
Fourth-Was it accompanied by any IN
usual nolSeI II SO, describe IL.
Fifth-Was there more than one shock
fet2 If so, how many? Where several felt,
give accurately or even roughly the number.
duration and character of each and the inter-
val between them.
Sixth-Which Of the following measures of
intensity would best describe what happened
in your vicinity? No. livery light, noticed
by q few persons, not generally felt.
No. Light, felt by the majority of
persons, rafting windows and crockery.
No. 3-Moderate, sufficient to set
suspended objects, chandeliers, etc., swing
ing or to overthrow light objects. No. 4
Strong, sufficient to crack the plaster in
houses or to throw down some bricks from
chimneys. No. 5-Severe, overthrowiug
chimneys and injuring the walls of houses.
Seventh. Do you know of any other cause
for what happened than an earthquake.
Give also any further particulars of interest,
stating whether they are from observation or
hearsay. For instance, whether the shock
seemed like q tremo- or jar or an undulatory
movement and whether it seemed to come
horizontally or vertically. whether any idea
of direction of shock was formed and if peo-
pie agreed in their opinion as to snch direc-
ton. Mention any unusual condition of the
atmosphere, any strange effect animals.
ct is often said that they will feel the first
tremor of shock some time
before people notice it at ALL.
Character of damage to buildings
general direction, in which walls, chimneys,
etc.. were overthrown. Springs, rivers and
wells are often nOticeaDly affected by even
slight shocks, and such facts are especially
interesting. If clock was stopped, give the
time it indicated and some idea as to how fast
or slow it was, it's position, the direction
which it was standing or facing, and the ap-
prOXimate length and weight OF its pendu-
lum. If the chandelier was noticed to swing
decidedly, describe it and state direction Of
swing. If pictures swung, state directions of
wall and whether pictures on the wall at right
angles to it were put in motion. If doors
were closed or opened, state the direction of
the wall in which they were set. In short,
hardly any fact, however insignificant, re-
garding this great earthquake will come
amiss, and it is probable that from the mass
OF information to be gathered, data of great
scientific value Will be deducted.
WHERE INFORMATION SHOULD GO.
1t is requested that this information shall
be sent to the division of volcanic 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 which occur in all parts
of this continent will be perfected and put in
operation. These arrangements have been
in progress for a year or more, and the most
advanced students of this branch of national
science 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 auto
matically recording earth movements. Per-
haps the best has for its central feature
disc of smoked glass revolved horizontally by
clock work Besides this are horizontal pen
dula delicately suspended upon pivotS. carry
ing sufficient inertia to keep their pendua
at rest, although the stands to which they
are attached be moved. Each pendula bears
at its extremity a pointer, which, being
drawn over the smoked disc as the latter re-
wolves, marks true circles as long as the
earth remains unmoved, but with the slight
est movement their course is disturbed and
their record is seen in
WAVING OR JAGGED LINES
around the disc. Two of these pendula are
required for each SeiSmOgraph, one recording
the east and west movements and the other
those north and south. This instrument is
too delicate and complex for use outside of
the observatories and laboratories, where it
can have the attention of trained observers,
but another and much simpler device has
nearly been perfected, which it is proposed
shall be placed in the hands Of volunteer OBJ
servers in many parts of the coun-
try. 1t consists of a vertical pen
dulum, whose point hangs over
cup of mercury upon the surface of which
lies platinum float. A small depression in
the float receives the points without m king
actual contact, except when the mercury is
disturbed, in which event the contact will be
made completing an electrical circuit,
which by Withdrawing detent sets in motion
the machinery of an ordinary clock. 1t is
intended that only one or two hundred of
these instruments shall be sent at present.
These will record only the beginning of the
earthquake, but they will serve also the pur-
pose of calling attention to a disturbance
which might otherwise escape notice and
thus enable the observer to note such other
features as the phenomena may present.
The study of phenomena Of this kind is
claimed to be of great value to science as a
guide to q knowledge of the nature of the
earth's interior and for its bearing upon
almost every branch of physics and geology.