The New York herald., 1877-02-26
THE IRON THREAD.
How the Wire for the Brooklyn
Bridge is Made.
TESTING IT'S STRENGTH.

Tho public beng vitality interested in knowing with
what and accuracy the contract s being carried
out, which awarded after much controversy by
the trustees Of the Brooklyn Bridge TO Mr.. T. Lloyd
Hagh for furnishing the steel for the four main
cables and other parts OF the superstrucure Of tho
bridge, and upon the proper strength aud durability Of
which will depend their lives, HERALD found his
way over Hamilton ferry to the works in South
brooklyn wherc tho wire Is now being made Dir.
Haigh's wire mills situated ut the junction Of
Inlay and William Streets occupy part of two blocks
and are now being extended SO as 10 facilitate the
execution Of the bridge contract The crude
rolled crucbe cast steel rods, which received at
the works from the rolling mills, drawn into wire
OF tho required slze which Is aferward galvanized 10
protect from tho effects OF atmosphere action. It's
company's engineers to see II II up to the
quirements OF the specifications and IL approved IL
ready for delivery
The superintendent, Mr. G. s. Howell, was foune su-
pervsing the erection OF ono of the buildings aud
when informed OF the writer's mission started him
through the works, IN company with a rather uncom-
muncaivc employe afterward joining him, and giving
every possible information.
HOW 1T IS MADE.
The rolled crucble rod Steel part of which has bee
furnished from the works OF Nichols Co. I. H. An
land IL supplied by Anderson l. Parsovant, Of
Pittsburg, Pa, ana there seems to be every prob
ability that this firm will continue to supply the rods.
This rod steel, which is rolled OVAL is by gauge,
1882 Of inch way by 1854 the other, is re-
ceived In tho form OF coils, weighing from 60 10 10
pounds ana about 200 yards In length Tho end OF
each coil is heated in blacksmths forge and then
pointed this being the lrst operation Tho cells are
then carried to the building across the street, whero
thcy cleaned from the oxidized scale which
forms all metal which has been heated and then al
lowed to COOL Fourteen to fifteen Of the coils are
placed in each cleaning vat and are lett there for
from two to two and half hours hot liquid.
sisting of containing avo per cent suphurlc
acid. The coils, when sufficiently cleaned, are taken
out and coated with limo prevent further acid ac
tion. They arc then thoroughly baked IN suitable
ovens for some ten hours. 10 thoroughly dry them
all traces OF the acid which II not efoc
tualy eliminated leaves tho coils brittle.
THE DRAWING
When these operations are flushed the coils are
ready be transformed into wire by being drawn
This drawing consists in pulling the wire, by Of
suitable apparatus through graduated holes IN steel
plates until II is drawn down to the required size. On
bench are placed rotating cylindrical drums
blocks, as the workmen Call them The wiro being
thrown over q reel tho workman inserts the pointed
end OF tho holes OF the drawplaie cam under
tho drum acts on u pivoted lever arm, 10 which Is
chained pair OF heavy nippcrs or 'pullers." When
the has passed the workman sciZes the udng
end OF the wire with tho 'pulcrs;' the then acts,
cxorting immense pressure on the lever the
being drawn some distance through tho plate. 1t 10
again seized by the nippers aud drawn forward until
it can be caught IN wise on the drum. The drum Is
then put into gear and rotates, drawing the wire
through the plate. The rod steel, which in passing
through tho plato becomes steel wire, is kept well
fabricated with tallow 1t through tho plate
The plates rectangular blocks OF peculiarly hard
see provided with conical openings the wire passing
from the larger opening which is about hall an inch
in diameter cut OF tho smaller one which is OF the SIZE
necessary tor one drawing The draw plates are very
carefully made OF steel specially manufactured for that
Inn m nf Anlut uyni
creased and quite hot but soon cools oil as passes
round the drum In order TO draw the rod steel 70 tho
proper size of wire for tho bridge 1t Is only drawn
twice.
The oval rod is drawn down to wire of No. gauge
or threesixteentn inch diameter, by the first pale,
aud from the second IT appears having the diameter
required by tho spcciheations--namey, OllG inch
which size ls known as Birmingham No. s. The wire
having pussed through the operation OF drawing S
we'll soaked with tallow, and has to be put in "picke
to remove all the grease before it goes through the
operation OF galvanizing The operation OF 'pickng"
consists In boiling the wire III vats containing weak
solution OF potash This takes some two or three hours
Alter tho grease is thoroughly eliminated the WIRE is
tempered In suitable ovens.
GALvANIzING WIRE.
Tho wire is now finished and ready to be galvanized
by tho depOstng of coating OF zinc on It's surface.
The coils carried across tho street again placed
on rcels from which the wire passes over drums and
back into the galvanizng bath. From the drums the
wiros pass under rollers into bath OF dilute muriatic
acid, highly charged with zinc. The acid bites de-
deposited, which. AS the wire passes through floating
hux OF sal ammonac into bath Of melted zinc, acts
a surface Of union for the two metals. The bath OF
melted znc which IL surrounded by six inches OF fire.
is kept at . temperature OF about 750 degrees
Fahrenheit Some twenty feet per minute pass
through tho melted zinc, and 1t Is supposed
that from six to pounds Of zinc deposited
on 100 pounds OF From tho zinc bath tho gal
yanlzcd wire passes through mixture OF coal dust
and moulding sand, which acts as cleaner and pol
sher ut angle OF 45 degrees for $50 feet, when It
reaches large reels over which II passes perfectly cold
and under great tention on to the cong reels. From
these last reels the wire taken OF coils OF five
feet in diameter the length of wre in each coil being
the wire passes utter leaving the galvanzing bath
patented process of Colonel Palnc, assistant engineer
Of the bridge company, and results Ia the wire when
in the direction Of tho rest Of the
quality and one demanded by tho specification. The
wire being finished II now only remains to test and
see whether comes up to the requirements OF the
bridge company as to strength ana elasticity. Tho
breaking strength and amount OF stretch are deter
mined by testing one foot samples taken from both
ends OF each COLL and by testing i've foot sample
from every filth coil. The samples exceeding tho test
ing dimensions sufficiently to allow OF firm gripping
are placed jaws OF the testing apparatus and sub
jccted pulling strain produced by weight placed on
u long arm, the weight being Increased until the
breaks under the strain The WIRE, before COM
mcncng the testing proper, Is subjected to pre-.
minary Strengthening strain OF 400 pounds The per.
centage OF stretch before preaknge Is noted on
graduated scae The specifications require that the
wire shall nave breaking strength OF over 8 400
pounds, with three and a-half per cent OF stretch.
A HERALD TEST.
For tho benefit OF the HERALD readers two tests
made IN presence OF the HERALD representative a
foot was tested each time. Tho wire was
placed 10 the jaws by Mr. George Stanley, workman
adjusting the APPARATUS. When everything was ready
Tor the test there was before stated strain OF 400
pounds on the wire. An employe, stationed on the
platform below the scale arm, first placed weights cor
responding 10 5000 pounds ON, then Increased the
weight TO 3S6, when the percentage Of stretch, as
noted from the scale by Mr. stanley ana recorded by
tho HERALD man. was three per cent. at $50 pounds
the wire broke, showing i've per cent OF stretch A
second sample was taken from another coil On
testing this with 5000 pounds ut starting II gave
two per cent OF stretch. A thousand pounds were
added and the wire sui stood the tremendous strain,
the scale recording our per cent OF srctch. On M
creasing the weights 50 that the scale marked $50
pounds the WIRE parted showing i've and three