Evening star. [volume] (Washington, D.C.) 1854-1972, 1860-01-18
GREAT IRON AOUEDUCT BRIDGE.

4 GREAT IRON AQUEDUCT BRIDGE.
Among the public works now in course OF
completion at Washington. one of the most re-
narSable though least known. is the Washing
ton Aqueduct Bridge over Rock Creek. ut The
western end of Pennsylvania avenue, now
nearly completed from the designs and under
the direction of Captain Megs. This bridge
4 cast iron arch of twenty feet rise and two
1undred feet clear span between the abut-
ments The arch consists Of two ribs. each Of
which is composed of seventeen cast iron pipes
of forty-eight inches internal diameter, and
twelve feet three inches in length. They have
Hanged ends pierced with holes for screw bolts,
by which the pipes are firmly connected to-
gether. After being cast, they were placed in
lathe and the ends and hanges were accu-
rately turned faced off. They are put to-
gether in the form of circular arc the faced
ends abutting against each other, and forty
screw bolts firmly secure each Joint Such is
the accuracy obtained by the present use of
machinery in engineering that these joints are
.water-tight, under the aqueduct pressure of
12u feet head, by mere application of the
dressed suTfaces of cast iron, no packing or
cement being used in the joints.
[ pom these two arched ribs, which are firmly
connected with each other by east iron tubular
cross braces and heavy wrought iron diagonal
ties. i, erected frame work of heavy rolled
irJG III beams, from the works Of the Phoenix
Iron Company of Philadelphia, supporting two
Cuntimuous horizontal iron girderS. of two hun
dred and four feet SIN inches in length. Upon
these girderS rest cross beams of timber. sup
porting the roadway of the bridge, which en-
braces two city railroad and carriage tracks
and two paths for foot passengers
The cDTnIce of the bridge Is decorated with
.'oi,HfoHS of cast iron, and a light wrought
IRON railing surmountS the whole.
The abutments, founded upon solid rock are
built in the most substantial and durable man
Ev,p If
blocks from the Government quarrieS at Sem
eca. upon the Chesapeake and Ohio Canal
twenty four miles from the city of Washington
the strength of this stone is seventeen thou
sand pounds per square inch.
This bridge is particularly remarkable for
the double duty which the arch performs.
W hlle 1t supports roadway, forming a beau
tiful and much needed communication by
which the traffic between the cities of Washing
ton and GeOT setOwn is carried over the water
of the Washington aquduct is conveyed into the
city Of Washington through the pipes of which
the arch Is composed To guard against all
danger Of freezing, the pipes are lined with
rtaves and resinOus pine timber, three inches
In thickness, leaving clear waterway liz each
rib of three and half feet in diameter
The fangeS and bolts by which the pipes are
connected at the joints are covered with deco
rdtive mOuldings, encircled with foliage in cast
iron. The arch ribs spring from ornamental
blocks Of granite set in the skew back Of the
abatmGnt>. The intersection of the beams in
the frame work Of the spandrilS, are covered
with ornamental bosses, also of east iron The
whole is model Of lightness and elegance,
being two hundred feet in clear span and forty
FIVE feet in height from the water to the top of
the parapct.
The abu;mentS contain vaults. in which are
the connecting pi pes and StOp-cOeks for reguls
ting the flow and discharge of water. and in
western abutmentS on the Georgetown side.
one OF the vaults serves as M engine room and
contains high pressure engine-the first, it is
believed, erected in this country.
This engine, drawing its supply from the cas-
iron street mains Of the Washington aqueduct
pumps ten thousand gallons Of water per hour
into reservoir on the heights OF Georgetown,
q mile distant, and two hundred and four feet
above the machine. This reservoir supplies
that portion of Georgetown which is above the
level Of the great store and distributing reSer-
vOirs of the Washington aqueduct.
The engines and pumps were built by III. b
Worthington, of New York, under his patent
Cf ISJ5.
The masonry Of this bridge has been execu-
ted by MeSSrs. Carman Il Dobbins, of Phila-
delphia, contractors. The iron work by
MeSSrs 4. Il W. Denmead & Sons of RaIti-
more. The style of the work is crcditable Ia
those engaged upon it. The Washington adue-
duct has other works not less remarkable
than this one; among them, the great granite
a:ch, by which the masonry aqUeduct nine feet
ii diameter, crosses the Cabin John Creek nj
height of one hundred and one feet above
the bed Of the stream. This arch is built of
hewE granite. Is twenty feet wide fCty-Spypn
feet three inches riso, and being two hundred
and twenty feet in clear span. is the LARGEST
stone arch in the word.
Had eitl er of these bridges been constructed
IN Great Britain, the public press would have
teemed With illustrations snd descriptions of
them, NJ d every reading man, woman and
child in Europe and America would have been
a> familiar with their history as with that of
the Menai Bridge OF the Great Eastern, while
In Washington they are executed, and few but
those who have bestowed upon them the
thought and toll necessary 70 their design and
construction seem to know of the existence of
such national achievements of science and
skill.-Ihiia. EUenlHs JoDrnal