The Forest Republican. [volume] (Tionesta, Pa.) 1869-1952, 1889-09-18
A WONDER OF THE WORLD.
SCoTLANDS NEARLY FINISHED
FORTH BRIDGE.

A writer in the Londor Neies has been
visiting the nearly completed great
bridge over the Firth Of Forth, a few
miles from Edinburgh. He says that
on arriving at South Queensferry he
noticed what seemed to be a small man
of-war lying in the Firth near the bridge,
but she seemed no bigger than a penny
boat on the Thames. His surprise was
great on learning that it was her
Maiesty's steamer Devastation; and he
began to understand how this powerful
iron-clad was dwafed into ittleness by
the towering mass of ironwork above
her
By taking a stroll along the shore he
says the observer gets another impression
of magnitude, As he leaves Queensferry
behind, the houses, from the laws of
perspective, become small, but the three
great cantilevcrs do not seem to diminish
in the least. If you walk far enough, so
that Queensferry has entirely disappeared,
you find the vast masses of iron ap-
parently standing up in the sky as high
as ever st. Paul's dome. as well as st.
Peters in Rome, are also, he adds, good
instances of this mode of testing great
altitude.
Naturally the Eiffel Tower comes into
his mind for comparison. The statement
is made that one of the cantilevers of the
bridge, with its connecting girders, if
set up lengthwise on end, would be very
nearly the same height as the Paris
tower; with this difference. that the can
tilever has twice the amount of metal in
it that the other has. This last detail
also implies twice the amount of labor in
the construction, Now, there are three
cantileyers in the Forth Bridge. If
these were all added together with the
girders and put up on end the whole
would be three times higher than the
Eiffel Tower.
And yet these statements are far from
conveying the full difference between the
two structures, either as to size, strength
or quality of workmanship. The follow
ing figures will give some idea of these
heads: The Eiffel Tower contains only
1000 tons of iron, while the Forth Bridge.
when finished, will have absorbed over
$4,000 tons Of the finest steel that could
be procured, These figures speak for
themselves, and the difference in the
metal tells its own tale. The Forth
Bridge was begun in 1888, and will have
taken about seven years to complete,
while the tower in Paris was run up in
about as many months.
"The bridge proper" continues the
writer of this letter, sis Just over mile
le nth l,,,t thara l.
end connecting it with the high ground,
and these together add half a mile more
to the length of the work. The Tav
Bridge is about two miles long, but it
has not the height nor the vast proper
tions of this at Qucensferry. This one
had to give height, so that the largest
vessels could pass under, and the space
below the span for this purpose is $50
feet. To attain this height and yet to
have the necessary strength, the canti-
levers tower high above, and they re-
quired an elevation as high as St. Paul's.
Let any one take the map of London and
measure a mile alcng one of the main
thoroughfares and he will begin to realize
the space brIdged over by the three great
cantilevers. There are two wide spans
and two half spans. The large spans are
each 171O feet wide, this being about the
distance along Regent street from the
Oxford Circus to the beginning of the
Quadrant. 1t is the throwing of con-
nection-it might be called an arch, but
although the shape justifies the term, the
principle of construction does not
across this extended space that consti-
tutes the mark of distinction in the en-
gineering work. The tubular bridge at
the Menal Straits, which was the wonder
of the day, does not reach over much
more than fourth of the distance we
have covered, between the supports.
"The word 'cantilever' is a technical
term meaning particular kind of
bracket, and the arch form is here pro-
duced by means of two gigantic brackets
which stretch out to what would be the
keystone Of the arch. These brackets dc
not meet-a space of $50 feet is left be-
tween-but they are sufficiently strong tc
support girders, by means of which the
two ends will be connected and the road.
way carried along. The cantilevers are
now all but finished. They stand and
seem to be stretching out their arms OF
both sides, as if wishing to shake hand.
with each other, and the $50 feet of space
which is yet left between seems very
small.
81 have had the satisfaction Of ascend.
ing to the summit of the central can't
lever with Mr.. Cooper, the chief resident
engineer. We went up in lift, but the
lift in this case is not the least like thosC
in London hotels. There is no lncloseC
shaft, and you feel as if you were in
balloon. The cage is pulled up by Al
iron rope, which seemed like thread il
the air as ! looked upward and traced j
to the top, a distance Of 800 feet, whicl
we were about to mount up to. BY mean
Of these lifts the men are taken up anC
down to their work, so there are a mum
ber of them at various parts of the bridge
From the summit we looked perpendicu
larly down to the water below, where w
had perfect bird 's-eye view of every
thing. The Devastation looked yer
small affair, and the officer Of the watcl
appeared only as a dark speck as he pace,
up and down the deck.
We had a fine view up and down tn
firth. At another part of the bridge
saw the riveting machine at work. Thi
is worked by hydraulic power, and it fin
ishcs off a riyet in a few seconds wit