The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1874-09-05
BRIDGING THE MISSISSIPPI.


BRIDGING THE MISSISSIPPI.
DimcaIty Of Avoiding an Obstruction OF
NaviSation-A New Bridge ut Prairie
Du CHEN which Satisfies Both Rail-
road and River Neutrality-suspicious. OF
the Structure.
PRAIRIE Do CHEN, Wis, August 70, 1874.
From the carry settlement OF the Western coun-
try, and especially since the introduction OF rail-
ways - means OF transit one OF the most I'm
portant problems presenting itself for solution has
been how best TO secure the sale and rapid
passage of the Mississippi, River by trains, &C.,
without obstructlng its navigation. Rats have
been the greatest cause OF anxiety to bridge
builders, for they are commonly $40 feet
in Width. SO that no ordinary draw
bridge could be constructed to permit them
10 pass unbroken. The river men have
enormously opposed the construction OF piers in
the channel Notwithstanding this they have
been constructed at various points, and are noto-
riously an obstruction TO navigation. Aside from
this, the cost OF ordinary bridges Is so great that
few corporations could be founa willing to risk
such an outlay, even ir the money could be OBJ
tanned.
COURAGEOUS ENTERPRISE.
Various schemes for transferring the cars across
the river have been tried and proved failures The
success is the transfer steamer. which is at best
clumsy, slow and expensive method. To overcome
tins dirriculty has been the work and study OF
many eminent engineers. but 1t has remained for
practical man, experienced In the peculiar re-
quiIements OF the case, to solve the problem and
construct . bridge which, for Its simplicity, Sc
curity and adaptation, IL unsurpassed. 1t re-
quired small amount OF courage 10 risk $780, 900
in an experiment which was almost universally
considered visionary scheme.
the river between Prairie du Chen, Wis., and
North McGreg0r, Iowa. il divided into two
branches by an Island. The eastern Tor Prairie du
Chien) channel is solely used by the large steamers
OF the different packet lines; the western Tor North
McGreg0r) channel Is exclusively the waterway
Py ra These 0 e, a Psu me ssaaa M
the Mississippi River aud the object OF the bridge
was to connect them.
The bridge IS constructed OF piles driven into
the bed OF the river, over which rests a
single railroad track. The length OF the bridge
one shore to the osSer there are Two
eSannel consists Of three pontoous. connscsed
lengthwiso firmly, and representing distance OF
ss SIDE an 70
The draw over the western channel consists OF but
one pontoon, having . length OF 4os feet, breadth
OF % feet height OF ~ feet ana draught OF IL
inches. When trains are passing over the draught
of both draws incresses TO about IS inches. The
bridge ana ne pontoons is overcome y aprons Or
movable tracks, which are adjusted 10y means OF
6y the men who are s,atioued on the pontoons for
other purposes, thereby involving no extra labor
or expense. Inc connexions between the ends OF
| pie DEVICE counterbalanced BY equal weights, SO
| that one man clamps and unclamps the end OF the
pOntOOn when swung into or out Of position.
THE CLOSING AND OPENING OF EACH DRAW
| 10 effected by small engine OF twenty horse
Wound chain the extremities Of this chain are e
secured to clusters OF piles above ana below the
30 S sve s sar
rent in one minute and closes against 1t in three
nsus
the power of tine engine.
the direction Of the current strikes the eastern
space OF ass feet the former channel and ss4
iull lorce on them. lss
In relation to the navigation OF the river. the
captains and pilots freely and frequently assert
river. and consider It no Obstruction Whatever t.
navigation. The most influential river men, and
those most deeply interested IN hindering II.
1--WE are Of the opinion that this bridge is an i'm
provemenL over the bridges now being built over
the Misslssippi River, aud less dangerous to nsvi
CATION, whether by noats or RATS"
States Army, ii his report to Congress- refers to
this bridge In the folio wing words:-
"While the bridge IN question Is exceptionally
free from objection as an obstruction to navtga-
tion, it conforms TO existing laws regulating the
bridging OF tho mississippi River In that Ii afF0rda
excellent facilities Tor steamers and tafts to pass
through the draw opening"
/ THE PASSAGE OF TRAINS.
In relation 30 tue passage Of trains 1t Ia proved
to- AFFORD greater security than ordinary draw
bridges. TOR the pontoon Is capable OF floating q
weight six times greater than that OF the heaviest
trans. aud there is danger oil accident from the
breaking Of overstratned spans II affords facili-
ties for the passage OF 1000 cars day. the average
number being now about SOC.
The cost Of the entire structure and lis appur-
tensnces Is one.stxth OF that or the most nexpen-
stve bridge across the river, and One-hfteenth Of
the lowest estimates IOr contracting IRON draw
| bridge at this point The expense OF operating 1t
h far below that or operating any drawbridge
across rhis river. The time required for It's CON-
structiOn is not over ninety days, and very much
less at points where material and labor are abun.
dant. TO these great advantages add that Of an
immense reduction Of the tolls and expense OF
crossing the river below that which 10 charged by
other bridge companies, and 1t Is readily under
stood how great and lasting benefit has been
conferred ON commerce and navigation BY the de-
sfgner and builder.