Orleans County monitor. [volume] (Barton, Vt.) 1872-1953, 1883-05-28

| NfASo iIlO oIA COIupdl tiuCuIo, WAICA
were connected by means of doors.
This great box was made water-tight
and then anchored on the spot on
which the tower was to stand. The
caisson was protected from the river
by coffer-dam of piles and sheet
ing. The work of building the tower
on fhe caisson was at once begun
and continued until enough weight
was on top of it to keep it on the
river bottom. There were large
wrought-iron tubes or shafts in the
roof of the caisson through which
earth and stones excavated on the
inside could be taken out, and there
was an air-lock for persons to enter
the caisson.
When it was sunk on the river
bottom the water was forced out of
the caisson by compressed air, and
men could go in and work. One
pound of air pressure equals two feet
of tide water, SO for every two feet
the caisson was lowered, one pound
had to be added to the air pressure
inside. Gauges in the engine-room
above indicated the height of the
tide and the pressure of air. The
highest pressure attained in the cais-
son was 81 pounds to the square
inch, in addition to atmospheric
pressure. At that pressure a man
could not whistle, and candle blown
out would Immediately ignite again.
Fresh water springs appeared. Be-
meath this caisson blasting and exca-
vation went on for months, when a
depth of 45 feet was reached, and
the caisson was then settled on rocky
foundation. The inside was then
filled with broken stone and concrete
until the whole thing was solid
mass and then the work of erecting
the tower went on rapidly.
Greater difficulty was encountered
on the New York side, and the cais-
son was made stronger and bigger,
and had to be sunk to a depth of
seventy-eight feet. Even at that
depth solid rock was not discovered.
But jagged points of rock stuck up
here and there, amid bed of quick
sand. The points of the ledge which
appeared only under one end of the
caisson swere levelled off and the
quicksand was confined within a wall
of concrete, the whole area of the
caisson was filled with the same ma
terial, after which the tower was
erected and finished like the one in
Brooklyn.
There were many interesting Incl
dents in the work of building the
foundations. The pressure of the
compressed air would sometimes tilt
up caisson and portion of the air
would escape, throwing up large
column of water fifty to sixty feet
high. One Sunday morning a ne
glectful watchman caused a blowout
which covered the adjoining buildings
and shipping with coat of mud and
injured two or three persons. Under
extreme pressure some of the work.
men became subject to certain physi
cal arrangements which have receiv-
ed the name of caisson disease. The
Brooklyn caisson caught fire several
times and twice had to be flooded
with water. In December, 1870, a
careless laborer placed lighted can
die on shelf in close proximity to
the oakum caulking of a timber joint,
which ignited, and under the pres
sure the fire made it's way into the
timber and out of sight. AS the
pressure was all outward no flame or
smoke could be seen in the caisson,
and it was some time before the fire
was discovered. Colonel Roebling
was summoned and he entered the
caisson at o'clock p. N. and did
not leave it until 5 a. m. Overwork
and anxiety, in addition to the many
hours in the compressed air, had it's
effect, and he was partially paralyzed
before he reached home. This was
the beginning of the disease that has
SO long prostrated him.
The towers built of granite brought
from Maine, are 276 feet inches
above high-water mark. The Brook
lyn tower reached its full height in
May, 1875, and it's New York mate
in July, 1876. The New York tow
er above the top of the caisson
weighs $4,000 tons. The frmness
of the foundation is shown in the
fact that the tower has not settled
two inches. At height of 119 feet
there are two arched openings in each
tower, through which will pass the
streams of travel. On the top of the
tower are saddle-plates, huge iron
castings, on which rest the weight OF
the cables.
The cables are fastened in anchor
, ages $50 feet distant from the tow.
ers. The anchorages are built o1
stone, and are 129 by 119 feet at the
/ base and SO feet high. Over the tol
5 of them run the roadways. Imbedde6
f in the two anchorages are huge plates
Q of iron weighing twenty-three tons
: each, to which are fastened iron bar:
: formed into chains, at the end O
q which are the cables that hold up th,
n suspended part of the bridge. Their
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