Delaware gazette. [volume] (Delaware, Ohio) 1855-1886, 1870-04-15
THE EAST RIVER BRIDGE.

we take the following account from the
| Rural AezV Yorker, is designed to effect
closer communication between the two
great cities of New York and Brooklyn.
In conception it is grander than any
thing of the kind previously dreamed of,
and its successful accomplishment will
prove one of the proudest engineering
I triumphs the world has ever witnessed.
The late John A. Roebling, who con-
structed the Niagara and Cincinnati sus-
pension bridges, originated the design,
and its execution is entrusted to his son.
The bridge is to be supported by four
cables, resting on two piers situated on
the shores. These piers are to be $40
feet apart, and two hundred and eighty
feet high, and the bridge-bed will rest
one hundred and thirty feet above tide
water, thus offering no impediment to
navigation. The cables will consist of
parallel steel wire, and will be nearly one
foot in thickness. They will be anchored
in solid masonry, 1887 feet from the
pier on the New York side, and eight
hundred and thirty-seven feet from that
on the Brooklyn side. Thus the real
span viii be 1874 feet in length and
the approaches beyond these points will
be of arChed masonry, thrown, like the
half-spans between anchorage and piers,
over streets and houses. These ap-
Proaches will commence at the City
Hall Park, IN New York, and at the
junction of Fulton and Sands streets, in
Brooklyn, and although rising but three
and a-half feet to one hundred, will offer
small obstruction to street travel.
Naturally, the piers must be capable
of withstanding an immense strain.
Their base at water-line is to be one
hundred and thirty-four feet long by
fifty six feet wide, and the heaviest
masonry is to be employed in their con-
structiOn. Each will contain over ooo,-
900 cubic feet of granite, and will weigh
over 10000 tons. In each pier there
will be two arches, for entrances to the
bridge, and each arch-way will be thirty
two feet wide, giving passage to a rail-
road track, a carriage-way and a side
walk. The bridge will weigh Z, 800 tons,
and it is thought this will be increased
by transitory weight of trains, carriages, |
horses, ETC., to little less than 6, 900 tons. !
To insure complete safety, therefore, the |
foundation of each pier will number H.
600 square feet of surface, upon which |
the pressure will be only about four tons
per square foot.
A proper foundation for these massive |
piers is of the greatest moment. Labor !
upon the Brooklyn side was begun in
January last, and has since been contin- !
ued, dredging machines being employed |
preparatory to sinking the colossal cais-
son which has been built at Greenpoint. |
This will be foated into position at high |
tide. The caisson, necessary because |
the Brooklyn shore presents no rock /
basis, is constructed of white pine tim
bers foot square, the seams tarred to
render them water-tight, and sheath
ing of tin between two of felt placed be-
tween the outside layers of timber to
make the whole alright 1t is one hun
dred and sixty-eight feet long by one
hundred and two feet wide on the out
side, and fifteen feet high. The sides
are wedge-shaped, the lower edge being
eight inches, and the upper something
over eight feet, in thickness, and the
roof resting on these sides is five feet
thick, leaving a working-chamber nine
feet in height. All the timbers are bolt
ed together with one and a-quarter inch
bolts, varying from two to seven feet in
length, and the structure is made as firm
as possible in every way.
Six shafts, lined with boiler iron, pass !
through the roof of the caisson, in which |
the water therein collected will rise to |
the height of the tide outside. Two 9TH
er shafts will allow the passage of work
men, and the removal of earth from
within. Air-pumps will force air into
the caisson through air-shafts, expelling
the water, and enabling laborers to work
upon the bottom. As fast as these ex-
cavate the earth they will deposit it
around the shafts, through which a
dredging machine will lift it and dump
it into scows.
When this mammoth affair shall be
sunk to its desired position, thirty feet
below low tide, additional courses of
timber will be laid on top of it, to the
height of fifteen feet, and filed in with
and when the whole has be-
come firmly fixed in place, the tower
will be built on the solid foundation thus
secured. On the New York side it is
believed nothing of the kind will be
necessary, the nature of the shore there
being wholly different.
That the bridge when completed will |
be well secured seems certain. Each of
the four cables will enter the anchor |
walls to distance of twenty feet, and |
will there connect with the anchor-chains !
or more in length, and forming a down
ward curve of a quarter of a circle, in
order to convert a portion of the tension
into downward pressure. Then the
cables will not be compelled to support |
the entire weight of the bridge. Stays,
running from the top of each pier to !
the bottom of the span, will relieve much /
of the strain-indeed, Mr.. Roebling as
serts that the bridge would not fall if the
ables were removed, would only sag.
Those who considered the first sus-
pension bridge ever built as a very pret-
ty but fragile thing, destined to a speedy
will look with wonder upon
this latest success of the engineers skill |
when it shall link two cities together
and admirers of mechanical genius
everywhere may well exult over Ameri
can boldness and energy as here exhib-
tied. In the light of such accomplish
ments, we may well marvel over the
probable grandeur of the future.