Daily Davenport Democrat. [volume] (Davenport, Iowa) 1864-1874, 1867-02-22

this to D'Aubsson's formula for the sp
proximate discharge Of a river. it was found
to he g. 80 cubic fet, per second. The
aanroxrnate discharge behind Csmpheli's
/ land was also determined in he Same
foerntr, ara was found % te 10 ,2T6 BIC
fgci nwi second.
Msfii lie exception e PIC places where
'hc AuHs approach cl0.r - tie r!ysr she
backs are usually steep ard rrsIy.
i. Yolr ..ffcr of Ir-tfutt ous. am re-
epltd 10 "4ecaie he Chcte9 AID Rock
Island iafotd bridge on ny maps. and a.
e,r ~ '..e r.c,.on { the ,gtreat tsfuush
- hays. AMI state lis general - q ,ifce On
tie 'ese rss' ut on 81 the stream ~ esert
4 ID Of crai! The Dr. dge ], accurately
loca I'd on The map - the rapids hertwith
transmitted, aud also,n ~ enlarged seae
on shee, No. 2. A series of experiments
with floats sunk in the water two feet be-
low the surface were made. and the lines
taken bv them in floating down the stream
carefully fixed by frequent observations
with three ,heodoltes. The course OF each
is indicated on the map, and by an inspec>
ton Of i, il will be seen that the turn-table
pier makes an angle OF about sixteen dc.
grees with the direction taken BY the
floats. This was in low water The angle
Of incidence increases as the water rises.
Having obtained data sufficient t. en-.
able the TO state Its general influence on
tic free navigation Of the stream" found
that The subject had been thoroughly in
vrstigssei by more able engineers in 1853.
| refer to tie board Of Typographical engi-
neers convened, by an order of the Tcpo>
graphical Bureau, March !, 1859. and cons
-ist,ng Of Captains Humphreys, Meade, and
Franklin, of the ccrps oi toposr phlcal en-
gnress. From their report | extract the
following, which shows very clearly the in
nacucc II has on the free navigation Of the
tiver need only add thai my investisa-
items ar coHiorma'ory Of their Conclusions
Tie Chica,o ard Rock Island railroad
bridge "a ihiown FROM the Island Of Rock
/ Island to the CITY OF Davenport Iowa. and
/, Is supported by stone abumsnts On the
shores and six stone piers The spans five
IN NUMBER are go feet broad. tie draw
spas being at tie waters level (si feet
stage ! Il aud ll2 feet respectively The
whole length Of the bridge is ,53j feet.
1.-The piers, except those OF the draw, are
rs feet long and Z feet broad at the top, and
5s feet long and / fee. broad at the tot
tom; the two small draw piers are SO feet
long and 10 fec, broad at the top. and 81
feet long and II feet broad at the bottom; =
the punishable pier, including the guard>
pier and failing, IS $50 feet long, All feet
broad at tho top, and 1856 feet long, And As
! feet broad at the bottom
The following is the decision of the
board.
"is.. That the railroad bridge which
crosses the Mississippi river between Rock
lland. in the State Of Illinois, and Dayen>
port, in the State Of Iowa, is not construct
cd according to correct principles, refers
ence being had TO the interests Of naviga>
! ton.
I'D That the piers Of the said briJg .
are not OF the best form, and that there WAS
no practical I'll ,ulty in constructing them
OF the proper form. With the exception 81
the turn tabi. pier. the board is Of the opn-
ion tina, the detective form Of the piers il a
matter Of no material Importance.
I'D The only pier larger than Is neces-
sary is the turn table pier This pier, in
the opinion Of The board, should have been
constructed no larger than was absolutely
necessary to sustain the truss when the
draw is open aud protect it from injury
from passing bnats, II sht have been
constructed with length of 29j feet, af-
iordins ample support and protection. and
bein. actually 80 feet IN length, thu differ
ence. 90 feet, is Unnecessary, ard in the
opinion of the board ucrncpus The Of
feet Of making il larger than was absolutely
necessary is 10 contract thu water way, IN
crease the velocity, narrow the draw-pas-
sage, aud present M - sliiace for boats to
strike against, thus Increasing the difficult '
OF their passage through the draw la q
! pier 81 this SIZE the starting is of imports
ance, and the upper faces of the piers should
have been curved surlices.
~ !. The peers are not placed parallel
with the current, but at ang IS varyin
from - degrees 80 minutes. The effect oil
81 this ohli9ni,y II to treble the obstruction
to the How of the water ani consequently
70 affect tie increase Of velocity in The
same RATIO. Another consequence is that
the passages Of steamboats, and RATS
through the draw and between the piers
are rendered much more d iiicult ard haz.
nrt!ous furthermore, the draw on the lows
side is rendered usesss 10y the formation o.
all eddy therein.
18th The eddy on the Iowa side of tn,
punishable pier, rs nearly as could be esti-
ruated, is about ono hundred feet wide a
the loot of the pier. and the Turbulence 81
boiling ~ the water extends about livt
hgndr,d irct below. 'iis eddy Is con
staa''y saryiug IN It's position AMI ii men
Sssls. u eiects "a tie pass igc Of ba..g.
aseeldlus aul DESCRIBING IS undoubtedly
q + ul,r Ii IA mere difficult, on account q
t',s caFs required 70 avoid getting one part
lie boat ia It when another part is ia ib,
sosrsai Of he cfaw.
"sih Tie bridge is badly located, and
IN consequence oi tbs ba location, is a
greater obstruction t. the passage OF steam
beats and RAILS than would have been nee
essary had the loca,io? b,en coed. A J
sjle il tbs vicinity below Rock Island, out
Il the rapid current, would have been bet.
ltr. Tie Board havirs tins point in view
exsm ued the line o. the Terry between
Rock Island City and Davenport and found
there would be no prac ical difficulty to III,
erection OF a bridge a; this site, or near 1t
which il consuue'ed upon proper principles
would be Of no material obstruction to nav
iga,ion
Although there is lao evidence Of any spe
ciiic plan having been proposed for the i'm,
prov,ment OF these rapids, except that o
improving the natural channel itself by ex
cav.,tion, 50 as 10 give four feet depth il
low water and passage way 200 feet II
width, several pans nave been proposed. i,
general way, for overcoming the Difficult
ties.
II has been proposed to erect dams acres
the river. with locks for steamboats, an,
chutes for rats aud fiat boats, making
slack wafer navigation in the river. 4
careful inspection OF the map Of the rapid.
will show that IN order to carry out such
plan il will require at least two locks an,
three dams to avoid overlooking the bo;ton
lands between the river ard the bluff, On,
dam and lock should he located just abov
the town OF Hampton; The rcxl lock nea
the city of Rock island, at the lower end o
the slough. between Rock Island and Ga
Illinois shore; and one dam u the head an,
another at The foot Of Rock Island, betweel
1t and the Iowa shore but. without making
a detailed estimate of the cost Of such a plal
it seems 20 M al ose;hcr inadmsslbs f.
the following reasons, VIZ:
lst No craft OF any kind, however lnrg
or small, could pass up Stream without go
ing through the locks the smallest skill
and largest steamboats, " ou!d alike be sub
;,...1 ti.,s ,,o,..a,,ar.. - Ill