Evening star. [volume] (Washington, D.C.) 1854-1972, 1857-02-12
LOCAL INTELLIGENCE.
TIE BRIDsE QUESTION ESsIsEIR's
REPORT.

WASHINGTON, Feb. s, 1857.
SrR I have the honor to submit to you the
following report as the result of my labors in
carrying out the resolution Of Congress for
plans and estimates for permanent bridges
across the Potomac For the precise nature
and condition of the duty assigned me, beg
leave TO refer to the communication addressed
to me from the Department Of the Interior,
under the date Of the 18th Of September last,
which Is herewith annexed, marked GA"
The very limited time allowed me will,
hope, excuse any omission of details that
might otherwise have been properly presented.
II is evident that plans for permanent
bridge at Washington cannot be properly ma
tured without due regard to the interests OF
navigation, nor should the equally vital and
important question Of railway communication
be overlooked A thorough examination of
the river and adjacent country was therefore,
deemed indispensable. complete hydro
graphic survey, (see accompanying map. ex.
Tending a distance Of six miIss-from the
island rocks, called the Three Sisters, IA half
mile above GeOrgetoTn,) to Geesborough
Point, lone mile below the arsenal)-estsb-
fishes conclusively that some improvement in
the actual state of the river is imperatively
demanded The depth Of the Potomac at the
Three SistsrS is eighty-four feet, and thence
30 q quarter Of a mile below Easby's wharf
varies from twenty zone to thirty three feet
Below that point the current spreads itself
over an immense surface, gradually losing its
energy, until the channel presents depth Of
only ten feet at mean and eight feet at extra
ordinary low tides. As the tide rises only
three feet, this depth is wholly inadequate for
the purposes of navigation Further on, the
eausevsy of the Long Bridge SO contracts the
current that We again fnd depth of thirty
two feet Below the Long Bridge there exists
two channsIs-ths Georgetown or Virginia,
and the w ashington or City channel. The
former is by far the more considerable, until
the tides Of the Eastern branch exert their
beneficial influence on the latter. After the
junction Of the two channels, the water attains
q depth Of fifty four feet
Ii will be seen from this description, that
there are hsts separating the w Washington and
Georgetown channels, and extending as far
the Eastern branch. Ii has been very COM
mon to assume that these fats owe their origin
TO the causeway constructed TO facilitate the
erection of the Long Bridge. This, however,
seems TO me a singular confusion Of cause and
effect The causevay resulted from the fats,
not the fats from the eauseway. There ex-
listed originally a channel through their midst,
which, with or without the Long Bridge cause
way, must eventually have disappeared as
consequence of the permanent connection OF
Mason or Analostan island with the Virginia
shore. Examination Of old charts, as well as
nature, convince me that these fa.s date from
a period long sntecsdent to the erection Of the
causeway. That they have increased more
rapidly during tie past fifty years is but nat
ural, when we consider what vast deposits
must result from the freshet waters Of the Po-
tomac, now rendered dOubly tursid from
washing the shores of highly cultivated re-
gion Il must be evident that ploughed hill
sides furnish more alluyial deposit than un-
broken forests or grassy slopes. By the ope-
ration Of these and similar causes, many ports,
formerly deep and accessible, now scarcely
exist, Of which Bladensburg, in our immeii-
ate vicinity, and others on our rivers of the
Atlantic seaboard, are familiar examples
In many cases this state Of things admits Of
10 remedy without great and continued ex
penditures- The case Of the Potomac at
Washington is happily different. Here the
volume Of water Is amply sufficient, when
properly directed by one initial expenditure,
70 insure good and lasting navigation So
long however, as its energies are wasted by
diffusion over large surface, We must expect
q changeable and insufficient CD annel. have
therefore prepared the following plan, re-
curing comparatively small expenditures,
and which deem certain in its operation, and
leading 20 most enduring and beneficial re-
suits 1t Is but the completion Of a work
commenced by nature. 1t consists in open
Ing a clear waterway, Of l, 40 feet, along the
" eSAAA ISL4OfluA VI
the existing esusezay, and replacing it tenn
porarily by q wooden structure on piles; low
ering the dam connecting MasOn's Island with
the Virginia shore, so as TO bring il on q level
with extraordinary high tides, and terminal.
ing it upper surface by an inclined plane Of
masonry; dredging q short new channel across
. portion Of the fats building a breakwater
from the southern portion Of Mason's Island to
defect the current Of the river into the new
channel and. finally, retaining LOO acres of
the fats g. the mouth Of the Tiber, thus Civ
ing q continuous an deep channel along the
Washington shore. The Tiber, or more prop
cry the City canal, should be continued to
the new shore line, and guard-loeks be placed
aI its entrance into the river. The outlines
Of this plan are exhibited on the accompany
ing map
The advantages resulting from these ar
ranzements may be summed up as follows:
rs The permanent improvement Of naFiga-
ton. say permanent, because the river will
be confined in sufficiently narrow channel
for three-guarters of a mile below Easby's
wharf by the proposed breskwater, which it
leaves IN a direction normal to the Long
Bridge, finally passing, directly through the
opening reserved for it, and becoming tangent
70 q bold carved shore of wonderfully regular
outline 1t Is we'll known that currents in
curves form stable and deep channels The
current we have 20 deal with below the Long
Bridge can never be Of such violence as to
form an exception A remarkable corrobora
ton Of this fact may De found By referring to
. map Of the Potomac published as far back
as 1872 The Old Sr0Jh channel formerly Of
considerable magnitude, showed no disposition
todefect, although striking some wh at obliqu
iy against the Washington shore On the con-
Gsry, II followed its curved outline with will
Ing mathematical precision. An examination
OF TIE accompanying map must convince any
unparalleled mind that the proposed new
channel cannot by any possibility fDjure, and
viii in all probability improve the mouth of
the Eastern branch, on which the United States
have very important interests connected with
the navy. Lower than this, il is obvious the
regime Of the river cannot be affected by the
proposed changes.
II may be objected that there, perhaps, e.
lists some natural obstacle TO forming a chan
mel across the fats Fearing an objection of
this nature, thoughtit we'll 10 ascertain pos
lnVely the character Of the alluyial deposit
For this purpose | caused 10 be CONSTRUCTED
simple wooden rod, pointed with iron Two
men forced il down a depth Of feet below