The daily gazette., 1881-06-11


navigation TO fifteen feet at low water,
Is the construction of q jetty, which. |.
starting from the dyke near thelighthouse
Is TO extend into the Delaware river,
curying to the south and east and reach
ing a depth of about fifteen feet at low
water, with an approximate length of
loO0 feet. The design of this jet-
ty is two fold.
First. To control the ebb current
out OF the Christiana crossing the bar
escaping into the Delaware in such
manner as to compel if to main ain a
suitable depth and position.
Second. TO intercept the flood tide
IN the Delaware as to gather suffi-
eient amount of tidal water to main
tain the navigation in the Christiana.
Upon the tracing, handed me with
your note, | have marked IN pencil the
position of the proposed jetty. You
will readily see therefrom that the ebb
currents will be DETECTED scuthwest-
ardly SO as to join with those of the
Delaware without conflict. You will
also observe that while this jetty, when
built will reduce somewhat the action
OF the flood tide upon the shore above
the Christiana, it will not obstruct to
any serious extent the free flow and
action of the Delaware ebb, and that
consequently no injurious effect is to
be anticipated either to or from suita-
BILE wharf structures above the water.
The case is somewhat different with
regard to wharves south of the Chris
tiana entrance.
In the first place, the Delaware ebb
will be DETECTED off shore by the curv-
ed back of the jetty, and should there
fore expect tendency to fill along the
Delaware shore to the south.
In the second place, any wharf
structure extending off the, shore south
of the Christiana, if carried beyond, or
even as far as the lower water mark,
would, beyond doubt. tend TO inter
fere with the free movement of the
food tide upward and into the Chris.
tiana entrance, thereby tending, so far
az this influence shall extend, to defeat
one of the essential objects of the pros
posed jetty. ... b..
l am of the opinion, therefore, that
any wharf structures to be erected on
the Delaware shore south of the Chris
tiana entrance should comply with two
conditions
First. ihey should not extend beyond
a bulkhead line which, connecting with
the dyke inside the mouth should grad
ually separate from the opposite shore,
and curving back should fall into the
generally line of the Delaware river.
From the local lines of high and low
water, l should say that this bulkhead
line ought to lie inside the low water
mark and somewhat 10 the position
drawn In blue on your chart.
Second. The construction of the wharf
should not anticipate by any great period
of time the construction of the dyke
along this bulkhead line, since until this
bulkhead was approximately complete
the broken angles would have an injuri-
ems effect. ~
The matter of the Christiana has been,
owing to the importance attached to it,
the subject OF deliberation by the Board
OF Engineers in New York. The report
of the board has not yet been received,
but from my partial participation in Its
proceedings am justified on saying that
the construction of the city will be re-
feel solicitous therefor In the general
interest that great care should be exer-
cised in the planning of any structures
In the vicinity OF the entrance.
have presented the matter solely
from the engineering point of view.
There may be, and are no doubt, com
mercial considerations OF Importance In
addition. One of these is the. fact that
there will be much better harbor above
the jetty than below. The curves of
depth on your chart are incorrect, espec-
tally the 18 feet curve which lies much
further off shore than is shown. This,
however, is matter OF detail and not of
principle.
Yours very truly,
WILLIAM LUDLOW,
Captain of Engineers, Brevct Lie aten-
nt-Colonel United States Army.
The letter referred to the Commi tee
on Road to the River, and Council re-
sumed the consideration of other busi-
nooo