The weekly herald. [volume] (Cleveland, Tenn.) 1876-1888, 1879-10-02
THE WASHINGTON MONUMENT.

THE WASHINGTON MONUMENT.
A Novel Piece Of RnEineerinE-Putting n
New Foundation Under a ColHEln Weigh
ing Over 30, 900 Tons.
A remarkable piece OF engineering
that should attract attention as one
of the most wonderful achievements
ever known to engineering science is in
progress under the direction OF Lieuten-
ant Colonel Casey, OF the army. 1t is
the removal OF the clay foundation OF the
Washington monument, and the kubsti-
tuition OF an artificial foundation OF con-
crete. A similar problem Of equal mag
nitude was never attempted before, aud
tie attention of French and German
engineers has been drawn to the work,
which has hitherto been entirely un-
noticed in this country.
The Washington monument, which
has remained unfinished since the COM
mencement Of the war, when work upon
it was stopped, now stands, o solid shaft
of masonry, $50 feet high and weighing
1000, 900 pounds. 1t stands upon a
base OF clay, about twenty-five feet
thick, which rests upon a deep strata Of
gravel. When work on the monument
was resumed sometime more than a year
ago, it was demonstrated that the foun.
dation was not capable OF sustaining the
weight it must bear when the shaft was
built mp 10 the proposed height OF 526
feet, which would then weigh about 210,-
600, 900 pounds-the highest and heayi.
est columnin the world. So Col. Casey,
who had the work in charge, was com.
PEELED to study out some method of re-
placing the understructure with some
more substantial substance than clay
and gravel. AS the base OF the monu-
ment is only fifty-five feet square, the
difficulties Of the undertaking will be
readily appreciated; and a commission Of
experts pronounced it impossible, re-
commenting either the removal Of the
monument entirely until q new base
could be substituted or an alteration Of
the original design, so that the pressure
could be extended over a larger surface
than fifty five square feet. But Colonel
Casey determined upon what vas then
considered an audacious feat, of remov-
ing the clay foundation q little at q
time, and substituting an entirely new
foundation.
The plan he adopted was to tunnel the
monument a little at a time and fill the
tunnels with beams of hydraulic con.
crete, which, when hardened, is more
tenacious than granite. The work be.
gan about a year ago, and is now more
than half completed, showing the plan
to be safe and practicable. The first
tunnel was dug under the monument to
it's center, twenty-four feet deep and
four feet wide. When the excavation
was completed, it wal shown by delicate
plumb lines that were hung inside the
monument, that the monument had set
tied one-third of. an inch toward the
trench. By working night and day
Col. Casey had this trench filed with q
shaft OF concrete, rammed and hardened
-four feet wide by twenty-four deep
and extending sixty feet beyond the
edge of the base of the monument, 30
that when finished the concrete base
will be 175 feet square. When the shaft
was completed it was found that the
monument had ceased to settle not only,
but had returned very nearly to its equi-
librium. Then another trench was dug
on the opposite side, similar in size to
the first one The monument then set
tied about one eighth of an inch in that
direction, but when this trench was fill
ed with concrete it went back again,
and the plumb,line hung perpendicular.
Other trenches were dug and filed with
the artificial stone, at right angles to
the first, with a similar change in the
position Of the monument, so that after
six months work the structure had q
partial base of stone under it in the
form OF a cross.
AT present the work is about hall
done, and is going on so rapidly that its
completion is expected by the LIST Of
January, when the neglected old monu,,
ment will have under it n foundation
that will sustain 100, 900, GOO pounds
The construction of the beams is q mat,
ter of interest. The trenches in the
clay are filed with q mass OF broken
blue-stone, sea.sand, pebbles and Port.
land cement, mixed by machinery of the
most complete and perfect character,
and, when placed in the trenches, ram
med with enormous iron beams swung
on swivels. When completed, the foun-
detion will have cost nearly 500, 000.
E..-l T.. NJ