The evening Argus. [volume] (Rock Island, Ill.) 1861-1871, 1870-11-23


In many particulars the plan of the St
Louis bridge is quite original, and, when
completed, will probably be equal, II not su-
perlor to any structure OF the kind IN the
world. As BY the East River bridge the
system by which the base of the pIers Is
laid is that Of sinking. Colossal iron Gals
sons. open below and resting upon the sand,
and which, with the increasing weight of the
piers of substantial masonry built on top OF
them, sink deeper and deeper as the sand is
gradually excavAted beneath them. In order
10 render the cslssons capable of resisting
the masonry above, and the masses of sand
and water which surround them, the all
within is condensed by means Of powerful
pumps SO that their power OF resistance can
be increased to meet any exingency. When
the csisson strikes upon the rock it will be
filled with concrete, which will complete the
indissoluble connection between rock aud
pier. When the last particle OF compressed
sir in the caisson has given place to the in>
destructible compound OF cement and Stone,
ell that remains to be done Is to MI up IN
similar manner the perpendicular shafts
which communicate between the cir cham
Der and the upper world, aud the whole
structure of the pier is solid i'll compacsness
incorporated with the rock below. Both
piers are now nearly completed. The east
pier has been resting. with caisson, on the
rock since February 18th. aud the filling of
the cham bers was rapidly accomplished
The west pier is also nearly, if not fully
com Ieted. In the construction of both
piers the portions above water are built of
granite, whilst below low water mark lime
stone blocks are used. When completed,
the total height of the piers will be 1874 and
los feet spectively-the east pier being
the highest, because the rock on the Illinois
side of the river lies deeper than it does on
the Missouri side. The hexagonal founds
tioas Of the piers are gh.g two IN length.
and their amounts to from Is, 900 to $4,000
tons. The construction of the abutments
will be equally solid and massive. They
also extend downward to the rocks. On the
Missouri side of the river this was accomp
lshed without difficulty, but many obstacles
have been encountered on the Illinois side,
owing to the nature of the bottom. These
four piers will form the substructure of the
work Upon them the bridge itself will rest.
They will carry three arches, which, between
the abutments and the piers will be five
hundred feet each, and between the two
piers five hundred and twenty feet span.-
The possibility of erecting such long spans
considering the enormous weight they will
have TO bear, was at first doubted BY the
many practical engineers interested in the
work. Capt Eads. however, sustained on
one side by his calculations, ard on the
other by the example of the arched bridge
Of kulinburg, in Holland, which crossed the
Leok with q span of 500 feet as well as by
the plans of the English bridge engineer.
Telford, which are made in the beginning of
this century, was enabled to set aside the
objections. The best caststeel is selected as
the material of these arches. Each of them
will be double-thst is, consisting Of two
concentrio arches, twelve feet apsrt--And
Joined together by network of massive
steel braces. These double arches will be
stretched parallel with each other, four in
each span from pier 10 pier. Upon them
will be laid the upper structure of the bridge
in two stories, the lower of which is exclu
sively for railroads; and the upper for vehi~
oles and foot passengers. Being fifty feet
wide, both will afford ample accommoda
tons for all traffic that will cross the bridge.
The structure will present no obstruction to
the free navigation of the river. as the lar
gest steamers may pass under it without
as may arise from the danger of collision
with the piers during the season of floating
ice.
The approaches to the bridge at either
end are to be equally as substantial as the
structure itself. The street leading to the
bridge is one of tas finest and broadcast in
city, and like the whole of the ST.. Louis
shore, it descends rapidly as it approaches
ha rIv no
to prolong the bridge the comparatively
distance of l049 feet into the city in order
to reach the level grade of the avenue By
which it is approached. The vehicles cross
ing the upper roadway will pass directly
into the streets of St. Louis, but the rail
road trains will run into a tunnel 1890 in
length, which passes under the city and
terminates at the spot where the great depot
of the st. Louis Central road will be built,
and is now intersac ted by the Pacific Rail-
road, reventeen feet high and will be out
through for mos. of the distance. With the
approach to the bridge over the low, marshy
ground of the Illinois shore the company has
nothing to do, but dykes and trestles ofsub
stantial structure, branching off, according
to the convenience of the different railroad
com panies, to the North, South and East
will complete the connection. The upper
carriage way will be carried ont upon sub
stantial constructions to convenient point
in East St Louis.
The total cast of this work, $3.50 feet in
length, can only be estimated as vet, hut
the calculations of Eads. the constructing
engineer, may be accepted as approximate
ly accurate. His estimates are as follows:
rstr (ria md hut