The times., 1897-08-13
The Great Marble Shaft Is Daily
Out of Perpendicular.
A VERY NATURAL MOVEMENT
Capstone Circling Around I'm Space.
Always Has Done So and Ever
a. to the Reason OF the Variations
Indicators Detect Vibrations.

symboicai OF stability and inmutability,
shifts out of the perpendicular nearly
every day. In fact, this gigantic pile Uf
stone, that has for SO many years been
The most conspicuous landmark OF the
Capital on entering the city. rarely oc-
cupies the same position twice OH two
consecutive days. For eight years, in
fact, ever since the monument has been
Completed. scientific readings have been
taken three times a day 10 determine
how much out Of the perpendieular the
monument has defle cted. From these
readings it is apparent that now, and for
many years past, the Washington Monu
ment has had its capstone circling around
in space anywhere from one to four inches
from where 1t ought to be.
Let no one imagine from this fact OF
the monument getting a move on itself
that there is any danger of the big shaft
toppling over. It's on too firm a founda-
tion for that The early constructors OF
the monument, when il was commenced
back in tie 4O's did not build upon the
shif ting sands. Although the site selected
was at that tine marshy and on the
banks OF the placid Potomac, and might
have appeared insecure, they profited by
a lesson from the Bible, and first laid
a firm foundation. So firm, indeed, is
this that il can be stated almost with
Certainty that the variation of the monu-
ment is not due in any manner To an
imperfect foundation. Scientists do not
always agree as to the real reason of
the monuments variation, but it is gen
orally conceded by many of them that
it is Que 10 the winds and To contrac-
ton aud expansion OF the stone due To
the heat OF the sun.
That there are many prevalent theories
as to the cause of the variation, a reporter
who set out last week 10 observe the
phenomena soon discovered. In the course
OF one afternoon, various theories were ad-
yanced that it was due to the heat ex-
pansiou caused by the sun, to the winds,
To the movement OF the earth, to irnper-
ceptible earthquake shocks, to magnetism.
and TO an erroneous in dicator which failed
to register correctly. Several persons
even declared that In spit OF science the Y
did not believe the monum-nt moved at all.
III much easier TO prove tnaJ the monti
ment does move than to find out why it
nIoy es. There is an apparatusin the rnonu-
ment now, which was placed there by Gen
4 "
ment was completed, while he was at the
| head of the Engineer Corps Of the Army.
| THIS consists of d very delicate pendulum,
the slightest vibration OF whichis recorded
| by two telescopes with hair line perpendicn-
| lars in them This pendulum is suspended
in protecting cylinder of sheet iron,
which excludes all external forces which
might affect the stability Of the pendulum.
1 ~. iC "a bpaVZ hr4SS
weight, weighing probably twenty pounds
| and it 5 suspended by brass wire, which
is attached TO level iron girder exactly
I7t feet above the level of the floor Of
the monument. This point, ia feet up, is
| atthe center of gravity of the marble shaft.
| That is, If it were possible to suspend
| such a gigantic mass of marble FROM one
single point, where the weight would be
equally distributed, that point would be
found where the wire of the pendulum com
| mences.
IL is easier to understand when It is
explained that of the 81 ,720 tons whichare
! incorporated in the monument exactly one
half of the weight is above this point and
the other half below. If this center OF
| gravity should ever get outside of the
base of support, that is, the square founda-
fall over For instance, the shaft might
lean over so that the center of the monu-
ment at this 174 foot level were three
| feet out of plumb, and yet remain stable,
but in order for the mon umentto fall the
center of gravity would have TO move
goraethiug over fifteen feet. as natter
| of fact, the center OF gravity rarely
moves over an inch and fraction, so
| hot ha of ba aV
falling is compare lively Insignificant.
However Gen. Case ytbought thatit would
lie WIS 10 detect the first Indication of g
variation as soon as it happened, and he
therefore introduced the pendulum. Al
though protected from wind and other
influences by this cylinder, the brass weight
is suspended in small bucket of ater, in
order that it might be free from unneces-
sary swaying, and still free to indicate n
movement On support above the level
of the water are placed two telescopes at
right angles TO each other. Both have the
hair line perpendiculars found in all sur
veyor's telescopes, and 10th are adjusted
50 that the pendulum wire viii drop ac-
curately between these perpendiculars
The telescopes can be moved so as to get
I'm line with the pendulum whenever It
moves. Indicators on the telescopes show
how much out of plumb the pendulum Is.
One of these indicators detects the north
and south movement and the other the
east and west vibration.
AS the center of gravity is but IA feet
above the level, or trifle over one-thrd
Of the entire height, 1t follows that the
top stone of the monument moves over
three times the distance covered by the
center of gravity To be exact, whatever
distance the center of gravity is out OF
TIE perpendicular should be multiplied by
3.1S9, the number of times 174 win multi
ply into SOB, the entire height. The
reason is apparent to all who care to
work out the problem. Thus, IL the
| pendulum shows that the center of gravity
is out of the ordinary just one inch, the
ton stone must be 3.189 inches out oil
where it ought TO be. The monument
officials only trouble themselves to take the
readings Of tie center of gravity, because
that is the only important reading to b'
taken, ard the position of the rest car
easily be computed from this fact.
Mr.. John Hawkins the custodian Of th'
| monument, who has been in direct eharg,
of the big stone pile since it was completed
over eight years ago, chatted very enter
taining!y on the subject OF the varying
alterations of his charge. Mr. Hawkin
has taken the readings Of the Indicator
each day for something over eight years
and probably knows much more abou
the variations than anyone else connecte
with the monument.
1.-THE variation does not get more tha