Seattle daily post-intelligencer. [volume] (Seattle, W.T. [Wash.]) 1881-1888, 1884-01-04
Asefase ExGaSRxssxG rssuxps.
[Northwestern Lumbsrman.l

ASoT0gR gSGlSRxRsSG TasUMPa.
[NorthwesteEn Lumbefman.l
The completion Of the Michigan Gen.
tral esnti lever bridge over Niagara riv-
o. has added another laurel to American
engineering skill. and has opened no q
new 6old 0f bridge enQiaeerinQ, which
will b widely followed in the future.
There IL no other bridge in the world
built upon this principle, although two
moro are nov being built, one at the
Firth of Forth, Scotland, with q span
Of 160O feet, and the other over the Fra
zer river on the Canada Pacific road,
with span Of 3l5 feet. The principle
Of the osnti-lever bridge is that Of q
truseed beam, supported at or near the
center, With one end anchored or count
e. weighted 70 counteract she unequal
loading. Until the building Of the pres
snt structure there had besn no attempt
ct putting the pria"iple into practical
use, and the work on 90 large an under
taking has been watched with the ut
most interest by engineers throughout
the world. Il took three years to build
the suspension bridge over Niagara riv-
q, yet on April 18th . contract was en-
tered into between tho Central Bridge
Works OF Buffalo and the Niagara River
Bridge Company. which called for the
completion OF the present gigantic work
BY December lss, scarcely eight months.
The nrst Stone for the piers on the
American side was laid June Is, and On
the Canadian side July Ii. On August
y the 6rst column of steel for the tower
on the American side was lowered, and
ON the Canadian side September 10. The
nrst iron Tor the canti-lever was run out
September "a, and both canti-levers were
completed on November IL, the fixed
span being pat in three days later. The
magnitude of the work can scarcely be
realized from description of the con-
structiOn of the bridge. Over 10000
feet Of lumber and Is tons Of bolts were
used in the false work, while the iron
and steel used in the bridge weighs 5000
tons. The excavations for the piers we're
carried down until bedrock was reached,
when fsur blocks of "Beton Coieuet,"
20 feet wide, Is feet long and 10 feet
thick, were put In, and upon these
blocks was built tho masonry for the
tower supports, rising 80 feet above the
surface o: the water. The steel towers,
rising 100 feet above the masonry, we're
next built, and upon these the super
structore rests. When in progress Of
construction, Just before the fixed span
had bsen put in, tho work was visited
and inspected by representatives of this
paper, and it ID very certain that no
other work Of like character presents
% many features a. new, novel and won
derfully interesting from an engineers
standpoint.
After the shore arms Of the oanti-
levers had been built the difficult part
of the werk commenced, the spanning
Of 800 feet of that roaring torrent, 245
feet above its surface. To accomplish
this feat two immense travelling dor
ricks were used, the largest ever built,
calculated 20 sustain q weight of 81
tons, and projecting more than 40 feet
without support. With these defricks
Vie sections of the canti-levers, each Is
feet in length. we're rapidly constructed.
After one panel Of % feet had been
built and its braoing adjusted, the dr.
rick vas moved forward, and work on
the next section commenced.
Tho bridge has the longest double
track truss span ever yet built. The
total length Of the bridge proper 10 500
feet, 8 inches; length of each canti-lever,
395 feet /; Of fixed span. l19 feet, 8
inches; of clear span across the river,
l94 fest, inches; hight Of stone piers,
20 feet; of steel towers, 80 feet g inches;
Of clear span above the river, z39 fest
total weight resting On steel columns,
500 tons weight of each anchorage,
800 tons. The bridge has besn built 70
carry upon each track at the Same time
. freight train Of tho heaviest character,
extending the entire length Of the
bridge, headed BY two consolidated"
engines, while at the Same time resist
ing side pressure of 80 pounds to the
square foot, equivalent TO wind hav-
ing velocity Of 76 miles per hour, and
under such Q load the bridge ID not ex-
pected to be strained more than one
nth Of ito ultimate strength. An in
geni0us Arrangement TO o0mpeusate for
expansion and contraction has been
provided between the ends OF the oanti-
levers and the fixed span, permitting
the ends TO move freely With changes Of
Temperature, yet maintaining perfect n
gidity against aide pressure BY wind.
When the engineer corps lined the
bridge it Was out Of line in but ono or
two places, and the greatest variation
Wns les than one-Quarter Of An inoh,
yet no two pieces had been pat toRether
0utll tu0y W0tO Potm6000tiy pSoC90 N
the structure itself. The 1hore end Of
each canti lover y % firmly anchored
that IL will require an uplifting foroe ct
$40 tons on the river arm 70 diaplaoo Il,
and q tho utmost weight that can Be-
placed upon the river arm under any
conditions u 800 tons, the safety Of the
bridge has beeu carefully ASSURED.
The bridge hsa bsen built BY the Nj
OhiQan Central Railroad. in order that
the Vandesbilt interests might have An
independent crossing over the Niagara
river, - that their trafic might BE-
handled at all times without fear Of
being shut Of BY any combinations.
The bridge stands about ten rods above
the famous suspension bridge. and will
add sill another powerful attraction 70
ono Of the wonders Of the world. The
formal opening teok place December
-, when the bridge vas thorouRhly
tested in the presence Of largo crowd
Of Interested SPECTATOR.
The patriotic determination Of the
Berlin danes 20 eschev French milli-
merry forms the subject Of an amusing
article in L. Fvanrs. The writer. n.