The times., 1897-08-13

the daily observations to plan out chart
OF the movement, and 1T Is almost IN
variably toward the southwest. j guess
there is not much doubt that the sun
does have some influence on ii, but l
should think that the north side, being
coolest, would contract aud draw the
monument that way. Instead however
ii goes toward the southwest. am some
times OF the opinion that it is not due
TO the sun that the monument moves, be-
cause, on the hottest days, we can stiil
read the indications that point toward the
southwest.
1T has also been stated that the varia-
tion is due to winds. My experience has
been that on days when the wind was
blowing sixty miles an hour so hard, In
fact that you could not stand up by your
self out there on the hill at the very time
when you would expect the indicator To
show a great variation in the direction III
which the wind was blowing there would
still net be the least bending in that di-
rection. l have noticed that, time and
again. At other times in a dead calm,
have been surprised, on looking at the
Indicator, to find the pendulum swaying
and bobbing around as though the monu-
Inent was shaking in an earthquake. AT
such times it would indicate big yaria-
tion. This cannot be due to air currents
within the monument, becausethe pendulum
is protected by cylinder, and the indl-
Gators are protected in a closed closet. We
have tested the indicators when The ele-
vator is running up and down, inside the
shaft, but this has never had the slightest
| influence on the readings"
lit seems to me that the variation Of
| the monument must be mainly due to the
motion of the earth, and slight, irregular
| shocks that woul d not affect building OF
| a lower altitude. The sway!ns OF the
monument, however, has brought forth
{ many theories, and l guess it will be
| hard matter to settle finally just what
| does cause it,
| Has lightning ever had an effect on
| the shaft?'' was asked.
"No. 1t has never left any effects, ex-
| cept some burned out wires OF our electric
lights. Observations OF the pen dulum
| taken after the monument has been struck
| by lightning have never read any differ
| emily from those taken at other times"
Gen. Jonn NJ. Wilson, W no, in his capacity
| OF superintendent OF public buildings and
| grounds, had general supervision OF the
monument for the past seven or eight
years, begged TO be excused from express
| ing any opinion whatever on the variation
| OF the monument. He said that the pen
dulum and the indicators were Gen. Caseys
| scheme, and that he made it a point never
10 crticise anything ever done by fellow
| officer He would only say, however, that
| the walls OF the Monument were eighteen
| feet thick. of aolid stone, and that he would
| leave it to the reporters Imagination to
figure out just how far such substantial
stone walls could get out of the per
| pendicular.
Prof. William HsTkness, the superin
| tendent of the Nautical Almanac at the
| Naval Observatory, gave what is IN
doubtedly the correct explanation of the
shifting of the stone shaft. His explana
tion was that generally accepted 10y scien-
lists.
at has been known for a number Of
| years." he said, that the monument
| does move. There is no doubt OF that,
| for it has been proven time and again
| The cause is undoubtedly the expansion
of the stones on one side due TO the heat
of the sun. The sun strikes one side and
lengthens it out, while the opposite side
| being unaffected by the heat remains
stationary. This bends the monument in
slight curve. 1t does not lean over in a
straight line, tut bends like a bow II the
center OF gravity moves over a certain
distance, and this center of gra witty is
but one-third of the way up the shaft, YOU
cannot say positively that the cap-stOne
moves Just three times the distance the
plumb line indicates. am inclined to
think that it viii move a little more
than that, since the biggest part of
the curve would be above the center of
gravity. The exact distance the cap-ston @
does move, however, can he easily asoer-
tanned, though it would p robably take
some time TO make the calculations. :"
IL case this movement is due to the
sun, why does not the monument move
toward the north? The records show that
it invariably moves toward the southwest -
That is because in summer time. the.
sun. when it rises, Is In the northeast
II strikes the northeast sides of the monu
nIert, and bends it to the southwest By
tE, time the sun gets TO the south. the
monument Commences to move back toward
the north, and when the sun reaches the
west. late in the afternoon, it has moved
tn. stone shaft back again to the north
east, ST. that by evening, it Is almost in
its CIigina' position again The ein dications
| show that the stone invariably returns 70
its proper position at night. This is prob.
ably the only thing that affects the monu-
Inent and makes it move. The principle
Of the expansion and contraction of bodies
uAder heat and cold is q simple one and
easily understood ! t is this simple prin-
ciple, alone that works upon the Monu
Inent. in my opmlon.''
AS an illustration of the extent to which
a simple fact may be exaggerated, much
alarm was caused when the variation OF
the monument was first discovered Al
that time the variations were denoted by
hn unprotected plumb line which dropped
to the ground inside the shaft, instead
| OF in q protecting cylinder One day the
plumb line was observed to yibrate spas
medically. The monument was not neal rIy
completed, and the workmen at the tor
were much frightened at what they con
sidered were indications of a trembling
in the stone pile. An investigation dis
'loscd the fact, however, that an owl
had in some manner entered the shaft and
in endesvoring to find an exit had flapped
lis wings so much that the plumb line was
affected by the air currents.