, 1870-07-13
TIE HANNIBAL BRIDGE,


"MlAVH+ ~EA@IS
From Tie Hannfbdl tAo-> Courier, July7.
At 4 o'clock yesterday afternoon the location
Of the great bridge over the Mississippi, a
Hannibal WAS determined upon, and hence
forth the energies Of the engineers viii be az,
cluaiveiy devoted to its construction.
The bridge is TO strike the western blu1 a,
APPOINT 1,lGo feet above sozp Hollow, and
nois shore, at right angles with tho current,
The distance from Ehore to ehorc is 1880 feet,
and the structure will consist Of eight iron
spanR. resting on nine massive pieces Of ma
sonTy.
The dzst spsn Counting from the western
will be d1aw-spans, each 100 feet in the clear !;
The fourth span Will be $50 feet, and the fifth,
sixth, seventh, and eighth viii be 18o feet
each.
The first pieea OF masonry, or the western
Abutment, will of course te built upon rock
will be built on cold rock at \ depth Of t1cn-
ty-thxee feet below Low watet; tho SECOND. OF
draw pier, is to rest On the rock twcuty-eight
feet below low water; tho third pier will rest
on piles driven to tbs rock, and all the others,
Including the eastern abutment, Will be built
on piles driven twenty feet into the sand. and
thoroughly protected with rP-raps. AL the
piers are to be Of the best cut masonry, ana
the desigu is somewhat unique and very
pretty Some idcs Of their uaEnltude may bo
tA~% $>A@!AN
will contain :, 600 tens of masonry.
In front, or above the draw pier is to be al
immense ice-hreake1, E timber structure o.
feet long and 80 feet wide, which will contain
aeven thousand tons Of rip-rap. This monster
sunk to rock bottom and ''lo1ded.r Tho
largest steamer may dash herself to pieces
against it, but will never move it.
The bridge ia to be 3 I" "quadrAngu1ar Eirder."
commonly known ae the Pratt truss, entirely
~+&t Mod <7t-
lie ten feet in the clear above high-Bater
mark. A rolling load $500 pounds to the
equare foot, will not depress such
. structure over enc and five-eights
inches in the centre Of span. The
contract which viii be let within week,
track within eighteen months, and it is con-
tident1y expected that but fifteen months Will
be requisite. The plans and specifications
were forwarded to New York to-tay.
The draw ia to be worked by small steam
engine, and it is claimed that, 60 perfect wM
be its adjustment, that two men cau open or
c1ose it in one minute when there is no wind
But how to get through, over or around the
huge rock blur on the western bank-tl1e sum-
NIT Of which is l50 feet above the river, at the
cided upon Future travellers, after crossing
the magnificent bridge from the Illinois shore,
will dash at once into Cimmerian darkness, and
after tbreAding nine-degrea curve for $50
feet, through tunnel twenty feet high and
eighteen feet ride, cut through solid rock and
faced with solid masonry, viii emerge, cross
the northern branch Of the Soap Hollow Ra-
vine, skirt the blum southw1rdly, Cross the
southern branch, shoot through 4 thirty feet
cut in the blnH, south OF the powder magazine.
and find themselves gliding along the bank Of
the river to the levee.
From the west the brdge Will be approached
On descending grade Of seventeen feet to the
mile: and from the east on m ascending and
equal gr1de, over m embankment-
At present stage, the greatest depth OF VIA
ter in the channel is so feet, and the velocity
OF the current is ~ miles per hour.
On Tuesday it waa Thought 6oap Hollow
would be the objective point OF this aide of
the river, but more careful surveys proved it
to be impraeteabla.
1lr. Warren Colburn, consulting engineer,
consent to build wagon bridge. The addi-
Eona1 cost, Of course, cannot be given, but
rough estimate might be Set down st 81, 900.