The weekly Oskaloosa herald. [volume] (Oskaloosa, Iowa) 1855-1885, 1874-07-23

ciiP lue iolioWluB portion oI Tile ue-
scription given by that paper of the
great bridge at St. Louis.
"The bridge has three spans,
formed with ribbed arches made Of
chrome steel. The center span is
$40 feet, and the other. two 500 feet
each. The four arches forming
each Of the spans consists of an up
per and lover rib extending from
pier to pier, and horizontal system
of bracing extends between the ribs
for the purpose of securing the arch
es in their reletive distances from
each other. The two center arches
of each span are Is feet 81 inches
apart from center to center, and tho
upper member of one arch is secured
to the lower one of the other by a
system of diagonal braoing. The
roadways are formed by transverse
iron beams II inches in depth.
From the opposite ends of the iron
beams forming theroadways doub-
le system of Diagonal horizontal brac-
ing binds the whole together. The
extreme width is So feet inches.
The upper roadway is 81 feet wide
between the two footwalks. The
latter are eight feet in width. The
railway passages between the car
riage ways are each IA feet inches
in the clear and eighteen feet high.
Tha roiluouo oro oo~r,od o,,,u a.
wharf on five stone arches, each
26 feet wide, and enclosed by cut
stone archade Of 20 arches support
ing the upper roadway. They are
then carried en- brick arches into the
tunnel on Third street. On the Hi.
nois shore the railway reaches the
level of the East st. Louis railw ays
by descending grade of one foot
and half in every 100 for o dis
tance of 5000 feet. The carriage
road at the east end ,descends in a
grade of four feet in every 100, and
on the Missouri side the grade is
nearly level. The foot walks are
from the roadway by iron
railing about three feet high, and
the iron railing on the outside of the
upper floor OF the bridge is about
four and a half feet high. Gas
lamps have been erected on either
side of the upper floor, and the
bridge is always illuminated.
THE sUPERsTRUCTURK.
is the work of the Keystone Bridge
Company, Of Pittsburg. The con-
tract was made on the 26th of Feb.
ruary, 1870, and the chrome steel
was manufactured by the VIM.
Butcher Company, of Philadelphia.
A great deal of difficulty was en-
oountered in procuring steel of the
right quality. The slaves composing
the tubes were required to stand a
compresslve strain of 60, 900 pounds,
and a tensile strain of 10000 to the
square mon OF section, without per.
manent set. They withstood ten
sile strain of 100000 pounds without
fracture.
lhE WESI ABUIMENI.
is 115 feet above the bed rock of the
river, and contains 1850 cubic
yards of masonry. This was the
most difficult part Of the work, and
seemed for a long time to battle the
ingenuity of the protector. In his
report upon this portion of the work
the chief engineer says: ats site
has been for over sixty years a part
of the steamboat wharf of the CITY,
and as such had received ever kind
of useless material thrown overheard
from the various steamers lying over
1t at that time. The old sheet iron
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 q
Mississippi steamer, seemed to have
found resting place on this spot.
and constituted deposit averaging
Twelve feet in depth over the rock.
During the memorable fire of le49,
when twenty-nine steamers were de.
stroyed at the levee, the wrecks of
two OF them sunk upon the site of
this abutment."
THE EAST ABUTMENT.
The caisson of the east abutment
is somewhat different in construction
from the others, although made up
on the same principle. The main
shaft had at the bottom two air locks,
each eight feet in diameter, instead
of but one of six feet. The main
shaft was carried down into the air
chamber two feet instead of five.
The center shaft alone was used for
the workmen. The locks were of
extra size. The main shaft had an
elevator in addition to the stairway.
The east abutment pier is the lar
gest of all, and like the others, rests
on solid rock. The bed rock at this
abutment is "a feet below extreme
low water mark. 1t covers 5000
square feet of surface, and is about
one quarter larger than the base of