Evening star. [volume] (Washington, D.C.) 1854-1972, 1857-02-13
LOCAL INTELLIGENCE.
he BRIDeE QUEsrIoS-THE ESGISEEE's
RsFORr.-j Concluded

BgFORT.-t Concluded
DRAW.
The draw is SO arranged that, turning On a
central pier it opens two passages Of seventy
feet each. IL is thought that by this arrange
ment the interests OF navigation and of the
public travel can be best consulted. Two
vessels advancing in opposite directions pass
at one and the same time, and the draw is
then promptly closed. Again an approach
ing vessel may find ii much easier to pass
through one opening than the other, owing to
circumstances of tide or weather or accidental
position. The wind can but slightly affect
draw 50 symmetrically placed The force re.
CURED to maneuvre il will therefore remain
constant. 1t is proposed to move this draw
by two cspstans and four men, the number
now employed. Should one capstan or set of
gearing be injured, it could be easily detach
ed, and the strength Of all four men be ap-
piled to the other. The public would thus
incur no risk Of detention. The draw is form-
ed Of four boiler plate girders, the ends being
supported when the draw is opened by light
iron rods The draw bridge rests on rollers
revolving on an iron way prepared for them.
The boiler-plste girder he's been adopted as
being highly suitable for the purpose, accord
ing with the architecture Of the bridge, easily
protected against oxidation, and on that &C
count of great durability.
The draw will be thirty four feet wide suf-
fcieut for a single-track railroad, common
road, and sidewalks The cost Of the whole
structure, including three arches over the Vir-
Sinia channel, and modification of causeway
10 adapt it to the new level, amounts accord
ing to the estimates herewith submitted to
S3 25S OO0; without railroad facilities to
81 40 600; with solid inclined causeway and
suspension arch, to $4,000 600; without rail-
road facilities, to 81 SEQ, 0OO
present neither plans nor estimates Of a
suspension bridge for the locality now under
consideration, for reasons which, hope, will
be deemed fully sufficient to in tify the omis-
sion The low banks of the river at this
point preclude the possibility Of erecting a
rational structure at a sufficient elevation 20
allow OF the free passage of shipping Ad-
hitting draw, due regard to the interests
OF navigation would still necessitate the cree
ton OF supporting piers one hundred and
twenty feet above low water, and at some
points one hundred and eighty feet above
solid ground The erection CT these piers
would require very heavy expenditures, w
ing to their dimensions and the immense diff =
cultles presented by their foundations A
series of arches for a suspension bridge is an
unfavorable feature in any event, and becomes
still more so should the passage Of a railway
be thought advisable. A bar iron suspension
bridge Is expensive, and its duration uncer-
tain, az Its safety depends on the more or less
faithful execution of a vast number of wells
A'CA Cdu d WIG UIluke De llOug1L
more or even so durable, as when made equal
ly strong, it presents TO the destructive action
Of oxidation surface forty times as great.
Let me not be supposed, however, to condemn
suspension bridges under all circumstances.
A structure that may boldly and very appro-
priately span Niagara, or the Ohio at Wheel
ing, may yet be wholly unsuited to the Poto-
mac at Washington.
An elevation or a cast-iron arch bridge &C.
aOmnanIas this al
be handsome and durable although its ex-
Pense would be but little inferior to that of
the stone-arch bridge, which is greatly Supe-
nor IN durability and beauty.
1t has occurred to me that boiIer-plate
glrderS, resting on pneumatic cast-irOn cylin-
ders, would form substantial and economical
bridge, presenting, however, no attractions
IN an architectural point Of view An addi-
tional cylinder, terminating in an incline
plane, would probably form an efectual pro
lection against the Ice. The estimated cost Of
such bridge would be about $500 600.
Considered solely In an engineering and
unitarian point Of view, the most rational
construction, perhaps, that could be placed at
the site OF the Long Bridge, would be solid
stone piers, and light wrought-iron spans Of
ZOO 70 zoo feet. L was not authorized TO pre-
sent such design, nor would the limited time
at my disposal have admitted of it Should
plan OF this kind be desired. il could be
easily presented to Congress at its next ses
sion Its cOnjectural cost, according to very
general data, would be about $3.50, 900.
With regard to railroad ccnnexion, the Long
bridge site presents every desirable facility
A connexiOn with the Baltimore and Wash
lngtoA depot was thoroughly examined, and
most favorable results obtained The proposed
route would be from the bridge along Mary
land avenue to south street, thence direct TO
within short distance Of the canal, at which
point commences curve Of 900 feet radius,
leading to tunnel entrance at south d street
a tunnel z,ZJO feet long terminates the line.
1ns tunnel would be Of very easy execution,
requiring to be simply excaya ted, bricked over
and recovered. II would lie for a great por-
Ton OF the way under the Capitol grounds,
but at an amply sufficient depth to avoid any
interference with their disposition and ar
rangements This line would present no grades
OF over hfty feet to the mile /; would give suf-
nclenuy easy curves, and would affect the city
ouI signify, ss four streets, amongst them the
hlghly-lmportant one of PennsylYania avenue.
or, more properly, the street that forms its
continuation, pass over the tunnel and cor
sequently experiences no interruption Amap
and profile OF the proposed route accompany
this report giving every desirable information
EAsBY's WHARF
Inc next locality above the Lo3g Bridge
presenting apparent .cilities for the cons,r1c-
- % - AACm GtSDy Hlart TO the
Virginia shore, passing over the southern nor
ton Vt Aason's island 1t has been suggested
that a suspension bridge there could De so
constructed as not 20 interfere with nayira.
ton The location has been thoroughly ex.
amlned with reference to this object, but
without favorable results. The roadway would
Do 50 or 40 feet above the highest available
ground on the Washington shore, a feature
Objectionable In every way, and precIuding
the passage Ct railroad At such an eleva.
tion the bridge would be 900 feet in length,
at 6est 9 temporary structure, and Of immense
expense.
a bridge at lower elevation could be built,
out II necessarily presents the disadvantage OF
draw, and IN that respect is similarly cir
cumstanced to the Long Bridge II would
cause TIE same obstruction to navigation, and
not accommodate 20 large a number Of the
citizens OF ashingtOn. It's cost would not b,
greatly inferior to that Of any similar struc-
ture al the size Of the Long Bridge, nor wsulI
ITS foundations present much less difficulty.
Few test borlnga indicate depth of from 80
70 80 feet 10 solid rock, 10 reach which the cot.
" Aar H. L.HV