The Columbian. [volume] (Bloomsburg, Pa.) 1866-1910, 1872-08-16
The Rrnnklyn Rrid0e.

a New York paper, speaking Of the
East River Bridge, says that the pres
sure of air in the caisson now building is
thirty pounds to the square inch, or
twice the ordinary atmospheric pres
sure. Once in the lock and the entrance
closed, it becomes necessary to have an
equal amount of pressure before the door
into the caisson can be opened. To this
end air is forced into the lock until the
right pressure is reached.
Between twenty and thirty men are
at work in the chambers. The lowest
point reached in the excavations is
within nine feet of the rock. The aver
age depth of the sand, however, is about
fifteen feet. Already boulders Of trap
rock are found imbedded in the quick
sand these are broken up and hoisted
out by means of an apparatus similar 10
dredging-machine, working in huge
shaft filed with water. The men work
in relays or Watches" each "watch'
remaining in the cai5son for three hours.
| Working in that compressed atmos-
pher has its disadvantages, and the
men complain Of cramps sometimes,
which, Judging from their description,
must be very painful, as one of the men
likened 1t to "tearin' the flesh from yer
Leg" The low, dim-lighted chambers,
filed with mist, the shining pools of
water, and the men toiling in the tlam-
ing gas-light amid the rushing,
rumbling noise Of the sand syphons,
combine to make an interesting scene
not easily forgotten. "Try and WHISTLE"
suggested the conductor of the party,
and try they did, but without success.
Fucker their lips, and blow as hard as
they could, no sound approaching a
whistle can be produced. The voice,
too, had strange, unnatural sound, as
though uttered in a high key, all due
to the compressed atmosphere.
The interior of the sides Of the cais-
son slopes outward, not unlike the lips
of an enormous bell. In fact, the work
ing of the structure is upon nearly the
same principle as that of a diving bell,
the pressure of the air keeping out the
water. When the bed rock is reached,
and the caisson fairly settled upon it,
the interior will be filled with concrete
and masonry.
Twenty courses of stone have been
laid upon the caisson, and tho work Is
being pushed forward as rapidly as pos
sible. AT present the work is somewhat
retarded for lack of stone, which can
not be supplied fast enough. The
Company has expended s2,200,000.
This includes the amount paid for right
Of way. They have on hand material
amounting to nearly s350,000. Four
hundred thousand dollars has been ex-
pended for lumber, and S120, 900 for ma
chienery. 1t is worthy Of remark that
the Company having the stone contract
| offered 800, 900 to be released from their
| contract. This offer the Company de.
clined, believing that they could not
make such advantageous terms else
where.
Doubts have been expressed as to the
stability of so huge a structure. In re-
gard to this point, the superintendent
states that the opinions Of the most dis.
tiugnished engineers have been sought
upon the subject and they fully indorse
the plans. 1t has been thought by some
that it would be necessary TO build a
pier in the middle of the river, This
would be impossible, from the fact that
Congress would never permit it, and
even if it were built vessels would be
constantly carried against it by the
force Of the current and injured, and the
Company continually involved in suits
for damages. A wind travelling at the
rate of sixty miles an hour, which is an
extreme case, would not sway the
bridge, even at its great elevation. 1t is
expected that steam cars will run across
the bridge at the rate Of twenty miles
All hour, The entire cost of the struc
ture, when completed, is estimated a
$12,000,000 This is thought to be ar
outside figure.