Knoxville journal. [volume] (Knoxville, Iowa) 1874-1986, 1874-07-16

lowing il a portion OF the descrip-
tion Of the bridge, given by the
-. Louis Democrat:
The bridge has three spans, formed
with ribbed arches made OF CHROME
steel. The center span is J2D feet,
and the other two5 500 feet each. The
four arches forming each of the spans
consist of an upper and lower curved
rib. extending from pier to pier, and
horizontal system OF bracing ex-
tanls between these ribs for the pur-
pose cf securing the arches In their
relative distances from each other.
The two center arches Of each span
are 10 feet 81 inches apart from CEN
ter 10 center, and the upper member
Of one arch Is secured To the lower
ole Of the other by a system Of dag
pal bracing. The roadways are
ijrmed by transverse iron beams Il
inches in depth. From the opposite
On Is Of the iron beams forming the
rJaIways a double system Of diagon-
al horizontal bracing binds the whole
together. The extreme width is ~
feet 2 inches. The upper roadway Is
81 feet wide between the two foot
walks. The latter are eight feet in
width. The railway passages be-
tween The carriage ways are each II
feet inches in the clear aid ~ feet
in height. The railways are carried
o !er the Wharf on FIVE store arches,
cmh 2G f ct wide, and enclosed by n
cat stone arcade Of twenty arches
supporting the upper roadway. They
are then carried on brick arches into
he tunnel on Third street. On the
Illinois shore the railway
soIchcs the level Of the East
81. llyui3 railways by a descending
grade Of one foot and half In every
100 feet for a distance Of 5000 feet.
Tie carriage road at the eastern end
descend5 with grade OF four feet In
every 100, and on the Missouri side
the grade is nearly level. The foot.
walks are separated from the road
way by iron railing about three feet
high, and tile iron railing on the out
side Of the upper floor Of the bridge
IA about four and half feet high.
Gas lamps have been erected on eli
ther side Of the upper floor, and the
bridge Is always illuminated.
THE sUpERsTRUCTURE
j. The work Of the Keystone Bridge
Company, Of Pittsburg. The con-
tract was made on the Goth of Fcbru-
arg, 1870, and the chrome steel Is
manufactured by the VIM. Butcher
Company, OF Philadelphia. a great
deal of difficulty was encountered In
procuring steel Of tho right quality.
The slaves composing the tubes were
required To stand compressive
strain Of G0,000 pounds, md q tensile
strain Of 10000 to the square inch Of
section without permanent set.
They withstood a tensile strain Of
10000 pounds without fracture.
TIE WEST ABCTMENT
is ii5 feet high above the bed rock Of
the river, and contains ii 500 cubic
yards Of masonry. This was the
most difficult part of the work, and
seemed for long time to battle the
ingenuity OF the protector. In his
report upon this portion Of the work,
the chief engineer says: Its site
In been for over sixty years part
Of the steamboat wharf Of the city,
aHd rs such had received every kind
Of useless material thrown overheard
from the various steamers lying over
il during that time. The old sheet
from enveloping their furnaces, worn
out CRATE bars, old fire bricks, parts
Of smoke stacks, stone coal cinders
and clinkers, and every manner Of
things entering into the construction
of Mississippi steamer, seemed to
have found resting place on this
s,ot, and constituted a deposit aver
aging twelve feet in depth over the
rock. During the memorable fire of
1919, when twenty-nine steamers
were destroyed at the levee, the
wrecks Of two of them sunk upon the
site Of this abutment."
TIE EAST ADUTMENT.
The caisson Of the east abutment
II somewhat different in construction
f'on the other, although made upon
the same principle. The main shaft
had ut the bottom two air locks,
each eight feet in diameter, instead
of but one Of six feet. The main
A.. u.