Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1913-01-04
HEAT OF THE SUN.
Effects of Its Rays Upon the Wash
ington Monument.

Not many people have any idea as to
the enormous amount of heat that the
sun sends off into space. The earth
gets only n very, small portion of it,
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 in 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 of the Capitol building at
Washington is the largest surface of
cast iron in the world, and the effect
of the continuous heat of hot summer
Gay can best he appreciated when it is
known that this mammoth mass really
sways back and forth under the scorch-
ing rays until the top feather in the
cap of the statue of Freedom describes
an ellipse, the diameter of which on st
hot day varies from four to eight
inches.
The giant plinth base of the dome,
resting on the roof of the old sand
stone building, measures 1876 feet on a
side The greatest diameter of the
round dome is 125 feet, while the whole
iron structure is 21s feet high from
the old Capitofs 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 swells even the bolts
and beams of the inside before the
sun has made its circuit.
Tie southern side of the dome suf-
fers most from the heat. being cx-
posed longer to the sun, which passes
south of the zenith while on it's journ-
ey from the east to the west. If the
metal were exposed to a constant
| heating the result of the continuation
of such expansion as that received on
very hot days might prove disastrous.
! but as it is little, If any, permanent
| injury 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 is also changed
| in volume SO perceptibly by the sun
| light that the mammoth shaft of the
| Washington Monument sways back
and forth in the sun on a hot day. The
outer surface being of hard marble, the
| expansion is much greater than Ii
| would be had granite instead of marble
been used On a hot summer day the
sharp aluminium apex that crowns the
obelisk points to a position at leas'
four inches north of normal, but al
ways returns to it's proper position II
the cool of the night.
From the extreme top of the monu
ment inside long pipe runs perpen
dicularly To the bottom, leading to
small closet behind the elevator. I'M!
contains a long pendulum, whose Dol
hangs in vessel of mercury, Whici
prevents it's oscillation. Two station
airy transits with highly magnifyln'
lenses are focused directly upon th'
suspended wire, and through these eacl
culver of the monument is detected pe
ing magnifed on a fine scale gradual
| ed to thousandths of an inch.
Every morning at 10 O'Clock state
ment of this plummet line is taken am
reported to the War Department, an
> il was by this means that the enec
; which the suns rays have on the mug
: white shaft was discovered. I'M
plumb bob, of course, was placed
f, the monument for the purpose OF de
tecting any settling it might undergo
. and although the great weight or II
! mass has pressed the ground for man
!, decades, it has settled only sligh
fraction Of an inch in one corner
: Harper's Weekly.