Year: 1874

THE PLAN OF CAPT. OBSERVATION-DISCLOSURES OF THE


RIyER-JETTIEs EXTENDING THE BANKS OF A


PASS TO THE BAR WILL PERMANENTLY DEEPEN


THE CHANNEL,


In a letter to the Hon. William Window,
Chairman Of the United States Senate Committee on
Transportation Routes the Seaboard, Capt James
Eads has forth the principal arguments for his plan
of improving outlet OF the Mississippi, which is the
subject Of a bin adopted by the House Committee on
Railways and Canals, and now on the calendar OF the
Committee of the Whole. The plan contempates an ar
tiAcial extension of the natural banks OF OF the
passes from the point where they begin TO widen and
disappear the Gulf 10 the crest Of the par about five
miles distant.


The following are the chief points Of the argument
The river is carrier OF solid matter in SUSPENSION the
amount carried being determined by the rapdty of the
stream modified by depth As the banks and bottom
are easily disintegrated load lost by the water slack
ing at any one place quickly restored where the
rent again increases This and not friction by mpnge
ment the cause Of erosion In some places and OF the
formation Of shoals In Others Once loaded the rver
can carry no more. II the channel were uniform the
current would be constant and there would be neither
erosion nor deposition in the course OF the river.


II the volume OF water Constant, the current
would be regular; but If when the river falls 1t is too
shallow TO carry its acquired load that will be in part
denosited D the channel until the is thereby
increased that the remaining load can be carried This
WAS shown in the Of the Bonnet Care crevasse,


hare the river below IL shoaled up feet by the
s,ackened current. But when this reduction Of the
deph OF the river had Quckened the current there
no further deposit.


From this II appears how futile 1t would be to attempt
either 10 enlarge or TO diminish the normal size OF Its
channel, anywhere within its auvia bed As rapidly
as the engineer strives to deepen 1t without proportion
ately contracting it. and thus enarges 1t beyond the
capacity which these natural forces give It, just so rap
dIv will the current be Stacked by the enlargement and
the depos be dropped there, and thus lessen II again
And as fast he contract H. Just so fast Will the
prrer be increased the consequent scour enlarge
II aoain by deepening IT, The magnitude OF the channel
h determined by forces which II is neither necessary nor
prontabe for the engineer encounter The form Of
the channel he can control and alter II he widen H.
these forces WI inevitably snoal IL IL DC conac' '
they will Just certainly deepen IT,


These considerations explain the formation and char
acterstcs OF the passes AT the mouth OF he river Inc
strong central current Is maintained intact Dy the re-
duced depth over which the stream passes as II ex-
paDds, like shs tail. out 10 the bar Ihe Ve!oclty ol
the being ntained by sboang IN depth as u
expands IN width. IL s able to transport It's entire load
out beyond the bar, excepting ONLY that when u mas
dropped on the submerged and incpent shores OF he
Pass. Although the current Is strong out across Tue
bar. ~ soon checked because Of It's immense Wldth
and shallow depth by which great friction IN pfopoI-
Just outside the bar, and its constant outward gwth
thus assured While the growth OF the shores OF the
Pass follows in due order.


BY OF jetes II Is proposed to conne the waters
OF pass breadth OF 1900 feet TO the crest OF
the bar. The reduction OF the width OF the channel
from 10 600 10 2OO feet will keep up the momentum ~
stream far beyond the BAR and hence the river viii
be able carry 10 greater depths and into stronger
GulT currents that load which 10 now only able
deposit inst outside OF bar Capt Eads is satisfied
that engineering skin is adequate the construction OF
these jettes that they shall permanently defy the
equally confident that canal with locks will answer
the requirements OF commerce.