The home journal. (Winchester, Tenn.) 1858-188?, 1872-04-19
The Great Bridge across the Misslsslp.
nj at vt. Louis,

The superstructurc Of the Illinois
and st. Louis bridge will he formed
by three arches, which will be thrown
over the openings, which are, II 52O
feet and two Of SOP feet each, and will
be composed OF four parallel ribs,
each OF which will consist of two con-
centric steel chords, joined ydiagonal
braces. The distance between these
two chords will be twelve feet. 10
form these chords, or members of the
rib-steel tubes, each about II feet long,
will he joined together by sleeve
couplings. These tubes will he placed
against each other, the ends being
turned Off so as to give the angle re-
quired by the curvature of the arch.
There will be about 1000 tubes re-
| quiled and they will he eighteen
inches in diameter and weigh from
1850 TO $500 lbs. each.
The heaviest tubes will be required
neal the abutments and the lightest
in the centre of each span. Each
tube will consist of six steel bars roll
ed in such manner that when placed
together, they will form hollow cyl
inder like the slaves ola barrel. They
will be held together by Il sleeve en-
vel0pe one-lourth 0fan inch thick COW
ering nearly the whole length Of the
tube. The sleeve couplings will be
two equal pieces, each having the
form Of Il half circle with llanges ut
the ends. They have grooves, cores
ponding to grooves at the end of the
tubes.
Through the centre of the couplings
and through the ends of the tubes
will pass steel bars which will project
on each side of the coupling far
enough to fit into the eyes of the
diagonal braces. Between the ribs of
each arch will be strongtubular struts
and diagonal hracing to give the arch
the power of resisting the effects of
strong winds, which in such long
spans Is much more considerable than
most people would suppose, In the
calculations, the effect of Il hurricane
has been assumed as being equal to
go tons for the central span. The
four ribs mentioned will form the
bearing part Of the bridge. They will
spring from huge wrought iron skew
backs on the piles and abutments.
From the upper ribs will start the
omirII thn rnaL wov Thn INNER rood.
w,r wL;nh .tnho u.nd cnnr nrIinorv
traffic viii ha - fec wiLn md H.
nlnLo tvn eiIewolks Thnre viii he
fonr lines Of rails Ind ON if two for
street oars and two for other vehicles
About % feet below the upper road.
way will be the railroad tracks. Al
the levee the upper roadway will be
IS feet above the level of the street
and from there to Third street viii
have a fall of 3 feet.
The tramways and tracks for stree
cars will run from Third street in ST
Louis to about Fifth street in East st
Louis, Il distance of about 1900 feet.
NOW THE ~ M M
BUILT.
Tbe method odopled for buiIdinc
fine sunnrslrurture hos NOT hern at.
tnnntaI ON .nv Inf . few sm,
hridrps and there will he some new
frotIIrrs in if. The first tube will be
.crn,vnI tn fine skewhork before th,
latter i nut into nosiliou and thp,
thn fnur rihs will he mill ont simul
,~nnnnu.lv On holh ids If roch MOI
nl,riny thp iuhes i'm nos;tion and ioin,
mo- Air ends Inv ihe sleeve com
?, limnS oi tho u,mntinn nuttinr In III,
!, Ii,onnnl hr,rn.
49,. - a. ,
~ 'ii'h WY "oout ~ lec' Vi e"ti
e nv tan We oui.t CIV rom Piel9 ai'
a apu'iiie,'1 "l.i'uul any ou,e'uc sul
pon', uI' "tPtLao','S 1i1"sIaiit, vi IN
Iuei5'n Vi .no o''i'oi ooi'H '"o'
I, 'l'StIioto. n''Sli' suspplSlo'l loH
$ may pcliitioouccu, however, 'oa'eoo.
ll'e structure allo 10 SIVe IteIIllS .
l Siratel secll',S " ,ne "olhiiiVt'
ilei' u Poi!'. "oput W lett rom III
sheMp"ch nus netm ieacl'eu' som
ouls'ae support wiz ne required u
o~Imtn,anis viii n,nnuwhiIo nnrn han,
built up to the level of the uppc
roadway, and on them wlIl be bull
timber t~restles fifty feet high, an,
overthe tops of tllese chains compose,
of flat links, will he passed and ias
tened to the euds of the two opposite
ribs on the piers. On the abuImenl,
one end of the chain will be fastened
to the end of the rib, and the Other
will he anchored on the land. Then,
by means of hydraulic rams on which
the wooden t~restles will rest, such a
strain will be brought on the cables
as will bring the ends of the ribs to
their correct positions. AS tube is
added to tube the strain on the cables
will be adjusted to the increased
weight bv Increasing the pressure ON
fine rams. When near the closing OF
the arches another system of post.
and tension rods will be introduced
for the purpose of lifting the ends of
the ribs into their true position. and
then the closing tubes of the inner
riIs will he introduced and tLe twn
inside ribs conIpIeted,
u,uur,,r
mAlhhiAh USED liih bHii'oE.
The tubes composing the ribs, the
sleeve couplings, II Il great many