St. Johnsbury Caledonian. [volume] (St. Johnsbury, Vt.) 1867-1919, 1883-06-01

utilized as warehouses. At each end
of the bridge are station houses of iron
and glass, from which the cars will
run.
After the towers were completed the
next engineering problem was to get
the wires over them. The cables could
not be made and then lifted into place.
The first wire was
CARRIED ACROSS BY A SCOw
on August IA, 1876. 1t was lifted into
place over the towers and fastened to
the anchOrages. A second wire was
then run across and the two were fast
ened together, making an endless wire
running over driving wheels. 1t was
then an easy matter to run across other
wires, and making really began
on June ii, 1877. On August p, 1876,
E. F. harrington the master mechanic,
crossed the river in rigger's chair,
which was attached to the traveller"
wire rope. \ foot-bridge, running over
the top of the towers, was stretched
across the river to assist in making the
cables. That bridge was four feet
wide, and was laid on two small cables
-OO lCCi wv -IltU
wire ropes served as hand handrails 10
this pathway in the sky" Many per
sons made the perilous trip over it
while it was i'll existence.
When the cables were ready for their
loads suspended bands made of
wrought iron were fastened on ut in
tervals of seven and one-half feet. To
these bands were attached suspender
ropes made of sheet wires. These ropes
are made to hold 100 tons each, but
not more than ten tons weight will
come upon one of them. The suspend
er ropes hold up the steel structure
which forms the roadways.
On the approaches the width of the
bridge is 100 feet. Here the wagon
ways are paved with Belgian blocks.
and the fOotway, which is only three
feet above the roadway, has an asphalt
pavement. But from anchorage to
anchorage the bridge is different. 1t
is il deft combination of steel beams,
trusses, girders. and chords, 50 feet
wide, fioOred with timber, except in
the space reserved for the railway
tracks. The total weight of steel on
the bridge is 6620 tons. The great
delay in the delivery of this steel ac-
cording to contract postponed the
completion of the bridge for nearly
one year.
As now completed there are five par
allel avenues on the bridge The
outer two, nineteen feet wide each,
are devoted to vehicles. In the cen
tire is an elevated fOot-path fifteen and
one-half feet wide. On either side of
this are the railway tracks-one for
cars going to Brooklyn and one for
those coming to New York.
CAPACITY OF THE BRIDGE FOR TRAVEL.
The promenade has capacity, If
persons move at the rate of 200 feet
per minute, of allowing 45, 200 persons
to pass over every hour. The road
way will admit the passage of 440 We
hicles per hour of an average weight
of 81 tons each, estimating three NOV
ing vehicles in every 100 feet. The
bridge will sustain 10000 soldiers
marching, better than any ordinary
bridge.
The cars are to be propelled by an
endless chain, but when they reach
the centre of the main span they will
run to the end by their own gravity
and momentum, being under the con-
troll of brakes. Passengers will get in
at one end and will be unable to get
out until they reach the other end of
the bridge. 1t is calculated that eigh-
Uy cars, such as are used on the ele-
waited roads, can be kept in operation
ut once, twenty of which will be on
the bridge ut one time. Each ear can
accommodate 100 passengers, and 50,
600 persons can he taken across in an
hour.
The total length of the bridge is
$3.50 feet. The length of the river
span is 1895 feet, and at the centre il
will be I35 feet above high water in
summer, and l3S feet in winter, the
difference being caused by the effect
of the heat and cold on the steel. The
wind blowing at velocity of 100 mile,
an hour would not hurt the bridge
The greatest velocity of the wind here
is IS miles an hour. The centre o
the suspended structure is l5 fee
higher than the rOadways of the tow
ers. Not over 3 per cent. of the yes
sells that enter this port would have u
strike their topmasts i'll passing under
! the bridge. From anchorage to an
chOrage the bridge is 3460 feet long
and the total weight of the suspende,
structure is I7,75O tons. The cables
Chief Engineer Roebling says, an,
strong enough to pull up the anchor
ages, which weigh 10000 tons each
The bridge is to be lighted by lO
electric lights.