Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1912-12-13
HEAT OF The sun
Old Sol Has a Strong Pull at the
Capitol In Washington.

Not many people have any idea as to
the enormous amount OF heat that the
sun sends Of into space. The earth
gets only n very small portion Of H.
The head OF a pin placed twenty feet
away from an electric light gets
IN proportion to the light on the sur
rounding walls Of a room about what
the earth gets OF the suns light and
heat radiated into space Yet that por-
ton the earth does get is great enough
To cause great structures to move.
In fact. all stone or metal buildings
are constantly changing their positions
under the hot rays OF the sun. The
great dome or the capitol building at
Washington IS the largest surface Of
cast iron In the world. and the effect OF
the continuous heat OF Il bot summer
day can best be appreciated. says HHr-
pers Weekly. when II IL known that
this mammoth mass really sways back
and forth under the scorching rays IN
I'll the top feather In the cap Of the
stntue OF Freedom describes an ellipse
the diameter of which on q hot day
varies from four to eight inches.
The giant plinth base OF the dome.
resting on the roof or the old sand
stone building. measures 1876 feet on
side. The greatest diameter OF the
round dome Is l25 feet. while rhe
whole iron structure Is 21S feet high
from the old capitors roof to the base
Of Freedom on tue apex. The cast iron
covering this surface Is made in thin
sheets. Offering good conductor for
the heat. which swells even the bolts
and beams OF the inside before the sun
has made it's circuit
The southern side OF the dome suf-
fers most from the heat being expos
ed longer 10 the sun. which passes
south of the zenith while Oh its jour
ney from the east 70 the west II the
metal were exposed to II constant
heating the result OF the continuation
of such expansion as that received on
very hot days might prove disastrous.
hut as Il IS little il any permanent in
jury Is done. since the iron returns
regularly to its normal position as the
cool night comes on.
But what seems more remarkable is
the fact that marble * also changed In
volume so pcrceptihly 10y the sunlight
that the mammoth shaft OF the Wash
ingtou monument sways back and
forth In IN" sun on n hot day. The
outer surface being Of hard marble the
expansion is much greater than it
would be- hnd granite Instead OF mar
BILE been used. On u hot summer day
fhc sharp aluminium apex that crowns
the Obelisk points 70 81 position at least
four inches north OF normal but al
ways returns to It's proper position In
the cool OF the night.
From the extreme top of the mOuu-
Iuent inside a long pipe line runs per
peudicuiarly 20 the bottom. leading Co
small closet behind the elevator
This contains II long pendulum. whose
bob hangs IN vessel Of mercury,
which prevents its oscillation. Two
stationary trausitS with highly uag
nifying lenses are fOcusSed directly
upon the suspended wire. and through
these each culver Of the monument Is
detected being maruiGed on a fine
scale graduated to thuusaudths Of an
iuch
Every morning ut 10 o'clock state
mont OF this plummet line is taEer
ard reported To the war department
and II WIS 10y this means that the IF
feet which the suns rays have on IN,
huge white shaft was discovered. This
plumb bob. Of course. was placed II
the monument Tor the purpose OF de
tectinc any settling it might undergo
and. although the Crent weight Of ~
mass has pressed the ground FOR mau!
decades. 81 has settled only Sigh
fraction ot an inch In one corner.
This seems extraordinary when II 9
realized that it, weight oc Sl.72O ton
rests on foundation only 1861 fee
square and - fcet deep from a heigh
almost fifteen times that ~ the depth
The whole rests on the sandy bank o
the Potomac river. with the enormou
pressure Of five tons to the squar
foot. Not only does the suns hea
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