The Londonderry sifter. (South Londonderry, Vt.) 1883-19??, 1892-04-29
THE TOWER BRIDGE,

ton occupied eighty-three years. After
having served its purpose more than $50
years it gave place to the present struc-
ture, which was begun in 1924 and
finished in 1881. This is but one of six
teen of the finest ar, hitectural works of
their kind in the world that span the
Thames.
The first metal bridge in England was
erected in 1919 over the Severn, and it is
curious circumstance that Thomas
Paine was successful contriver of an
iron bridge, which in 1887 he proposed
to construct without any iron piers over
the Schuylliill in Philadelphia, as the
stream was apt to be choked with ice in
the spring freshets. His hackers becom-
ing bankrupt, however, the structure
was not finished and the materials were
used in England. This work was long
regarded as great triumph of art, its
span being 236 feet long with rise Of "a
feet.
Suspension bridges were erected in
America as early as 1896 by Mr.. Fin
lay, who in 1901 took out a patent, and
in 1911 eight bridges had been built ON
his plan. Subsequently, in 1926, chain
cable suspension bridge was built across
the Straits of Menai, which until then
formed troublesome obstruction upon
the great road from London to Dublin.
Many beautiful suspension bridges have
since been erected in Great Britain and
ON the Continent. The most remarkable
wire suspension bridge in Europe, on &C
count of1ts dimensions and height, is
that of Freyburg, in Switzerland, which
has a span from pier to pier Of $40 feet
and is suspended at the height of 1877
feet above the river which flows un-
der it.
One of the most wonderful achieve
ments of engineering art is the steel
bridge across the Firth of Forth, in Scot
land. 1t has the longest span, the great
est weight and the greatest length of
any yet built.
The structure shown in the illustra-
ton, which thousands of workmen are
now hurrying to completion, will be
known as the Tower bridge, inasmuch
as it will cross the Thames near the
Tower of London. 1t is one of the most
remarkable undertakings of the kind in
existence, spanning as it does what is
perhaps the busiest waterway on earth.
The popularity of its construction con-
sists in two huge leaves weighing $50
tons, each of which is raised and lowered
to level thirty feet above high water,
somewhat after the manner of an ancient
drawbridge, thus affording passage for
river craft They are shown in the cut
open. A hundred feet above this bridge
level is another roadway for the accom-
mediation Of foot passengers, who are to
be lifted to it in elevators running
through the towers whenever the lower
portion of the bridge is open and travel
is impeded. The cost will be 81, 800, 900.
A project is now under discussion for
spanning the Hudson river with steel
wire suspension cables that will support
highway fifteen feet loftier than the
great Brooklyn bridge and large enough
to accommodate six lines of railroad.
Its span, as contemplated by the engi-
neers, will be 1850 feet long and $50
feet above the water. Compared with
the Brooklyn bridge its length, includ-
ing anchorage, will be $500 feet; the
former measures 3,700 feet. Each an
chorage of the North River bridge will
weigh 100000 tons, while that of the
Brooklyn bridge weighs only 10000
tons. The cost is roughly estimated at
$16,000,000.
Among other suspension bridges in
The United States is that at Wheeling,
which has span of l ,0l0 feet; at Mag
ara, with span of S21 feet and road
way $50 feet from the line of the river;
at Pittsburg, with span of 1 ,345 feet; at
Cincinnati, with total length of 1920
feet and span of 1,057 feet. Other ex-
amples of advanced bridge architecture
and engineering are to be found in
many other sections of the country, and
the improvements continually made
show that American skill is fully abreast
of that of any other people in the world.