New Ulm review., 1913-07-09
HEAT OF THE sun
Old Sol Has a Strong Pull at tho
Capitol In Washington.

Capitol In Washington
SWAPS THE MAMMOTH DOME
on . Hot 0ay He Torrid Rays viii
DRAG the Massive Iron Structure
Way Out Of Plumb Turns the Same
Trick With Washington Monument.
Not many people havs any idea - "a
the enormous amount OF heat that tho
sun sends on into space. The earth
gets only very small portion Of It
The head of pin placed twenty feet
away from an electric light gets
in proportion to the light on the sur
rounding walls of a room about whac
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. Tna
great dome OF the capitol building at
Washing gton is the largest surface or
cast iron In the world. and the effect Of
the continuous heat OF hot summer
day can best be appreciated, says Har-
pers Weekly. when 1t Is known thse
this mammoth mass really sways back
and forth under the scorching rays un-
Ill the top feather In the cap Of tho
statue Of Freedom describes an eldpse
the diameter OF which on hot day
varies from four to eight inches. a
The giant plinth base OF the dome,
resting on the roof Of the old sand
stone building, measures 1875 feet on
side. The greatest diameter OF tho
round dome Is Us feet while tho
whole iron structure Is 218 feet high
from the old capit0I's roof to the base
Of Freedom on the apex. The cast IRON
covering this surface Is made In thin
sheets, Offering a good conductor for
the heat. which sweIls even the beieo
and beams OF the inside before the sun
has made its circuit '....
The southern side Of the dome SUI
fers most from the heat, being expeo-
ed longer to the sun. which passes
south Of the zenith while ON its Jour-
ney from the east to the west. IL the
metal were exposed to a constant
heating the result Of the continuation
of such expansion rs that received on
very hot days might prove disastrous.
but as 1T Is little If any permanent In
Jury IS done. since the iron returns
regularly to its normal position a. the
cool night comes on.
But what seems more remarkable IS
the fact that marble is also changed In
volume SO perceptibly by the sunlight
that the mammoth shaft Of the Wash
ington monument sways back and
forth in the sun on hot day. The
outer surface being Of hard marble the
expansion Is much greater than It
would be had granite instead Of mar
ble been used On hot summer day
the sharp aluminium apex that crowns
the obelisk points to position at least
four inches north of normal, but al
ways returns to its proper position TN
the cool Of the night
From the extreme top Of the nonu-
nent inside long pipe line runs per-
pendicularly to the bottom, leading to
a small closet behind the elevator
This contains long pendulum, whose
bob hangs in a vessel of mercury,
which prevents its oscillation. Two
stationary transits with highly mag
nifytne lenses are focused directly
upon the suspended wire. and through
these each quiver Of the monument Is
detected, being magnifed on 6ne
scale graduated to thousandths OF an
inch.
Every morning at 10 O'Clock state
! nent Of this plummet line is taken
and reported to the war department,
and it was by this means that the ef-
feet which the suns rays have on tho
huge white shaft was discovered. This
plumb bob, Of course. was placed In
the monument for the purpose Of de-
tecting any settling it might undergo.
and, although the great weight of its
mass has pressed the ground for many
decades. it has settled only a slight
fraction of an inch in one corner.
This seems extraordinary when It IS
realized that its weight of S1,72O tons
rests on a foundation only 1854 feet
square and 80 feet deep from a height
almost fifteen times that Of the depth.
The whole rests on the sandy bank OF
the Potomac river, with the enormous
pressure of five tons to the square
foot. Not only does the suns heat
sway the big obelisk, but at times,
when a stiff winter gale was blowing.
it has been reported as much as two
inches out of plumb.
| Misery Ahead.
| "More tough luck" whispered bis
wife.
i l.