The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1895-12-14
HUDSON RIVER BRIDGE.
The Greatest Engineering Work I'm.
taken in the World.
From the Scientific American.

The Secretary of War recently appointed
a Board of Officers Of the Corps Of Engi-
neers 10 investigate and report their con
clusions as to the maximum length of span
practicable for suspension bridges, and
consistent with an amount OF traffic proba
bly, sufficient to warrant the expense OF
construction. The leading features OF
the design upon which the estimates were
made were as follows \ steel suspension
bridge having clear span Of 5000 feet
between the towers and carrying six rail
road tracks placed side by side The floor
Of the bridge to be provided with stifen-
ing truss, which shall be hinged at the
centre and be 120 feet in depth; the bridge
to be carried ON 16 cables, arranged eight
on each side; each cable to consist of 5000
parallel steel wires wrapped together and
having breaking strength of %, 440 tons;
the diameter, inclusive of wrappings, being
215 inches. The estimated cost of the
bridge is S22, 1856, $40.
From an engineering standpoint it is not
the total length of bridge that determines
Its magnitude, but the length of the indi-
vidual spans. The cost and constructive
difficulties Of bridge building increase at a
rapidly increasing ratio as the span is
heightened. The Tay Bridge, in Scot
land, is twice the length of the Fort
Bridge to the south of it; but the design
and erection Of its two miles Of short grid
ers did not call for the exercise of one-ffth
part Of the skill and courage required in
throwing the huge spans OF the Forth
Bridge across the mile of deep water at
the Firth of Forth In like increasing
ration will the difficulties multiply in
stretching this mammoth structure across
the Hudson river
The seven wonders of the world, that
appealed so strongly to the ancients, will
! be completely overshadowed on every point
Of comparison by this crowning feat Of the
nineteenth century. Hmere bulk or mass
be taken as a standard of comparison, it
will be bigger and heavier than the great
est Of the works of the ancients, and i'll
the scientific knowledge involved in its
construction it will embody truths in chem
istry, mathematics and mechanics that
would bewilder the Egyptian builders OF
the pyramids even more than its vast
stretch of steel cables and interlacing grid
ers.
The two masses of masonry that will
have to be built on shore to resist the enor-
nous pull Of the 16 cables will in their
united weight and bulk rival the great
pyramid of Gizeh. The four steel towers
that carry the cables will each, in all pro-
liability, overtop the lofty Washington
monument and will be exceeded in height
only by one structure, the Eiffel Tower in
Paris Ethically, if we may so speak,
they will stand loftier than the last named,
inasmuch as the Eiffel Tower is merely
spectacular freak, whereas the four
great towers Of this bridge will reach their
full stature as part Of a great mechanical
structure erected for useful mechanical
purpose.
When loaded to its full working capac-
ity the bridge can carry in midair at q
height Of l50 feet above the river, IL
heavily loaded freight trains which, ii
strung out in line. would be two miles in
length This would represent total load
Of 20. 600 tons. Moreover. ii could carry
this load with large margin of safety IN
"a tempest of wind that would endanger
the stability of many of the adjacent build
ings in New York city.
1t is fortunate Judged from the esthetlc
point of view. that the great structure Is
to be built ON the suspension principle in
stead of the cantilever, as was at one time
proposed Apart from the much greater
weight and cost Of cantilever bridge,
there is by comparison everything to be
said in favor of the light and graceful ap-
pearance of the suspended bridge. The
lofty and tapering steel towers. with the
cables rising in long, sweeping curve TO
meet them 500 feet in midair, will form a
picture at once majestic and beautiful.