, 1877-08-25
YwE GREAT BRIDGE.

DETAILED DESCRIPTION OF THE STRUCTURE
As TT WILL BE WHEN CoMrLETED-riiE Z
ACCOMMODATIONS FOR GENERAL TRAFFIC,
RAILWAY CARS AND PEDESrRIASS-INGE-
NOUS ENGINEERING DEVICES.
As the great cables of Jhe East rives bridge
are now progressing steadily, and the work
OF preparing for the land approaches, which
have been already described, has begun, It
NAV be well TO give description OF that
part of the completed bridge known as the
suspended superstructure. The engineers
in charge Of this part Of the work-MeSsrS.
Hildenbrand and Vanderbosch-are already
hard at work on the calculations, speciilca-
tions and detail drawings necessary. With
the exception of the cable bands, which VIII
be manufactured by the bridge company,
the steel and wrought and cast iron work
viii be given out by contract like the cable
wire. From the four great cables, each I94
TO rs inches in diameter the roadway or the
bridge will be suspended by means OF steel
wire ropes L inches in diameter. The road
way VIII consist Of box girders placed =
feet apart, on which the floor pianks Will
rest. The qirders VIII be p inches deep
and $50 feet in length Is, the extreme
width of the bridge. Steel suspender ropes
viii be fastened TO the cables by means Of
bands of wrought IRON of an inch in diam
eter and inches wide, bent around the
cables at intervals of about : feet, Just over
the floor girders, and secured by screw nuts
t. wrought iron sockets The steel ropes
viii be fastened in the socket by being pass
ed into cOnical socket holes and the wires
opened out at the larger end and steel wedges
inserted The wires viii be bent down and
over the wedge and beaten close, and finally
melted lead viii be poured IN. At the lower
end the rope viii be fastened III a similar
manner in a east iron socket from which
two iron rods, secured by nuts, pass down
on the outside Of the floor ginter plates,
through plate rivited underneath the grid
er. and VIII be finally secured by mats. As
IN the centre of the river span, the cables
descend to within two feet of the floor for
some distance, say about one hundred feet
each way from the centre, wrought IRON rods
y inches IN diameter viii be substituted Tor
the steel suspender ropes. These Will be
fastened to the cable bands by bolts, and be-
low viii pass between the two plates OF the
cir,!ers and be fastened on the lower side Of
the bottom plates IN the same manner rs the
double rods from the steel ropes. These
iron rods VIII also be used some distance
out from the anchorages IN place of the steel
ropes. in order to make the structure firm
and steady the outer main cables VIII be
drawn in some eight feet from their vertical
plane IN the river span. The inner cables
for the same purpose VIII lie drawn out from
their vertical plane some four feet. IN the
land span the cables, when completed, VAL
spread out toward the tower, so that the
outer cables VIII need to be drawn in but
slightly, and the inner cables ont also but
little This arrangement wiil giTe inclined
sGspendcr ropes and rods.
THE TRUsSES.
The stihening of the doorway viii be part
II ACCOMPLISHED by six trUsses running from |
to anchorage the whole length OF
the suspended portion Of the bridge. These I
trusses VIII divide the bridge floor INTO i've !
separate Wavs which viii be described fur |
ther on Of these trusscs the four outer
ones viii be II feet in height, and VIII con
sist Of two J-inch channels, bars OF wrought /
IRON upright posts 9-inch beams and dag |
oral steel bars : of an inch by inches II /
diameter. The two inner trIsses VIII be II 7
feet IN height For the purpose OF further I
Stil.euing tie roadway there viii be diagonal /
STAYS running from the tops Of the towers to |
different points IS far cut on the bridge as I
100 feet land and riverward. The whole |
bridge VIII be suspended by system OF |
cables and ropes IN horizontal plane, 10 |
counteract the action of the wind, II the /
same manner that It IS suspended by yertl- /
cal system to sustain the moving and sta |
tionary load. These also VIII assist IN sup !
porting part OF the load. This viii be done !
by means of storm cables and storm ropes, |
Fastened TO heavy steel bars placed IN the /
OF the towers, and which Will pass 4
from tower to tower and from towers to an
chorages. The storm cables OF which there |
viii be two In each span, consisting each OF
three three-inch steel ropes, Will run out IN |
the line of horizontal parabolas from each (
side of the towers or anchorages to the op- 1
posite side Of the roadway and back to the /
opposite lower anchoraSes on the same side 4
Of the roadway they started from, thus cross.
ing each other at two points III the middle of /
and underneath the roadway IN each span
They VIII be fastened 10 every other hoor /
girder These storm cables Will be assisted /
by wire rope storm stays, which, III sIlnl- 4
lar manner with the diagonal stays from the 4
tops of the towers to the roadway, Will run |
from the steel bars in the masonry before |
spoken of to different points under the bridge !
floor as far as 400 feet rverward and land- /
ward from the towers.
Between the two outer sets OF trusses, |
which stiffen the roadway on each side, VIII /
be ways for general wheel traffic, two sets OF /
horsecar rails on each side and iron tramways I
arranged to accommodate any gauge OF waG- !
on OF carriage These traffic ways viii be
sixteen feet in width, and their flooring, ike |
that of all the bridge, VIII consist OF two
thicknesses of planking- lower of yellow
pine running across the bridge and SIX
inches thick, and the upper OF oak, running
Iengthwise and three inches thick. Between
the inside t-usses which form these ways and /
the inner trusses, IL feet IN height, there /
viii be the two ways for the railroad l3 feet
In width Finally, IN the centre OF the bridge,
between the two high trusses, VIII be the {
fOOtway Is feet IN width and elevated lee1 /
above the carriage and rail ways The foot /
way railing VIII consist OF WIRE netting IKE
that used on steamers, this being chosen as /
It offers the leass possible resistance 10 the /
wind. The flooring of the passenger Way
will be four inch plank. The outside truss I
VIII form sufficient protection ON the cus- !
side, fender being placed along the road /
way ioOr to prevent wheels from coming TOO /
near the truss.
TRUSS EXPANSION.
To allow for tie expansion ard eOntrae- !
tion Of the trusses, caused by the extremes /
of temperature, and which amounts to some |
twenty inches for the middle span, there /
viii be provided peculiar and ingenious ar
ranuement. At the end of each OF the d.
agonal stay systems above described the truss !
VIII be cut in two and connection made by a
heavy plate rivited to the chords OF the truss
on one side and sliding IN a series OF sleeves !
fastened en- the chords Of the other truss. !
AT -. l. -, l,o4b rit-ar. I