Delaware gazette and state journal., 1902-12-04
WnY 4 srEEn nRrDGE BUnys.
Remarkable Detail of the Work of Co,
structinK steel Spans.

WHY A STEEL BRIDGE b URSs.
Remarkable Detail of the Work of Com
strnctinE Steel Spans.
Benjamin Brooks, In Boston Transcript
The other morning came the news
from New York that the great Viii
liamsburg Bridge, though entirely iso-
lated from anything Of an infammable
nature except comets, into whose final
structure not single splinter of wood
enters, was damaged by fire TO the ex-
tent of $3.50, 600, which it will take
probably months to make good.
Perhaps q good way to explain how
such fire was possible and what the
task Of repair amounts to is to describe
some of the methods and details of
construction as i saw them going on
there a few months ago.
The first fine filaments of the ulti-
mate steel spider web which was to
carry the new stream of New York
and Brooklyn traffic were not parts Of
the final structure at all. Two big
reels of wire rope about the diameter
of fire hose came on lighters to the
foot Of one of the towers at the river
brink. The ends we're first hoisted
up, over the tower head and brought
down to the anchorage behind-not
the usual sailor mans anchor, but q
block of stone about as big as Fifth
avenue residence. Then the lighters
were towed across the stream, allowing
the cables to play out after them and
lie on the river bottom. At the other
tower they were again hoisted up,
taken to powerful engines and, while
the river was guarded to prevent
steamers passing, they were raised up
out of the water and into the air just
a little higher than the bridge cables
proper were afterward to come. From
these two were hung four himsy and
seemingly perilous wooden tootways in
an ingenious kind of wood -and-iron
frame, as we might hang two pictures
from the same hook on opposite ends
of the same cord II we put stick be-
tween the two frames to hold them
apart. The task OF setting the long
succession of frames clear across the
river was given to o few daring fellows
who could readily and easily hang in
sling 400 feet in the air with river
full of steamboats, running by under
meath. After them came the plank
walks, the handrails-and the rest was
easy. lAll these things are in ashes
now. H5
The next step was to stretch immedi-
ately above the footways finer cable
about as thick as ones thumb-upon
which was made to travel a large
grooved pulley. hung from it in an iron
sling. and provided with two ropes,
one to pull it toward New York, the
other to pull towards Brooklyn. This
was the mechanical spider that was to
spin the great suspension cables. There
were several such, spinning all day
long, week in and week out.
The wire of which the four suspen-
sion cables are made is about as small
in circumference as the little toy
pencils that come with silk string
and a tassel, but 1t is wonderfully
strong for its weight One square inch
of it-that is, bar one inch square
made of like nsaterial-would sustain
weight of 100 tons. Zone Numbered
tons of water In tank would be 10
feet square and IA feet deep. If we
attached the end OF this fine wire to
balloon and released the balloon, about
IL miles of wire would be lifted off
the ground before it broke with its own
weight. I5 possesses this unusual
strength partly from the compression
it gets while being drawn and partly
from its very fine temper. y But once
heat it red hot, unequaily in different
places, and then let it cool in the NJ
vember night winds, or throw water
on it suddenly, and it might be no bet
ter than SO much uncooked macaroni
and break into little bits under the
blows of tack hammer.
In the making of the bridge cables
the end of this fine wire is taken from
the reels, on which it is wound in
hundreds of miles, passed round the
goroved wheel of the mechanical spider
and brought down to a temporary
fastening. Then the spider starts
across, unwinding the wire from the
reel and trailing a double part of it
behind him along the footways. When
he reaches the other terminal the loop
is taken from the grooved wheel and
passed round an iron pinblock with a
back for another strand. So back and
forth he goes day after day over the
tower tops, leaving the strands behind
him to be gathered up by the work
mmen and bound into bundles. When
ever one length of wire gives out tie
iext is joined to it by screw coup-
ling, like those used on small gas pine,
so that each of the 81 parallsl strands
which make up one cable is virtually
a single wire about lib miles long,
passing back ard forth around the
end blocks, like woFsted in a skein,
When all of them are bound into one
bundle. making just comfortable
armful, there are 1880 fibres in all,
each bearing its part-forty- two hum
dred miles of wire 10 what looks from
the river like one rope. or enough to
reach from New York to the Sandwich
Islands. And there are four such ropes.
Suspension bridges are particularly
fortunate in the matter of sub-struc-
lures. Nothing has to be constructed
under them to hold them up till they
are done. For all that. there is inevita-
bly, great amount of Temporary wood
work throughout its length aad height.
We saw how under each of the four
cables ran a continuous wooden road
way. So up the tall towers 90 ladders
and galleries and under the shore spans
are props and beams and all manner of
wreckage in the latticing of the girders
themselves; SO that although we start
and end with an entire steel bridge
free from anything that will burn, we
have 1t, during its construction, as
completely bound in inhammable ma
terials as the martyrs Nero encased in
faggots. Hang all this hundreds of
feet high in the wind beyond the reach
of telescope ladders and fire streams
and, you see, the proposition of burn
ino n steal bridna 7l,aaav,,an .-n... ..----I-