The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1860-01-30

Among the public works now In course Of
completion At Washington, one Of the most
remarkable u the Washington Aqueduct
Bridge. over Rock Greek, at the western end
Of Pennsylvania avenue, now nearly COM
plsted. This bridge 10 cast iron arch OF
twenty feet rise and two hundred feet clear
span between the abutments. The arch con
sists OF two ribs, each Of which 10 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 wnicn
the pipes are firmly connected together. AFTER
being cast, they were placed in = lathe, and the
ends and fianges were accurately turned OF
faced of. They are put together IN me form
OF circular arc, the faced ends aoutuhe
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 aqneduct pressure OF i2o ieet head,
by mere application of the dressed surfaces Of
cast iron, no packing or cement being used In
the joints.
Upon these two arched ribs, which are firmly
connected with each other by cast iron tubN-
lar cross braces and heavy wrought iron d.
agonal ties, is erected "A frame work OF heavy
rolled iron ii beams, from the works OF the
Phoenix Iron Company of Philadelphia, sup
porting two continuous horizontal iron Cir
ders, Of two hundred and four feet six inches
in length. Upon these girders rest cross beams
OF timber, supporting the roadway OF me
bridge, which embraces two city railroad ana
carriage trac Is and two paths for foot passen.
gers.
The cornice of the bridge is decorated with
modtilions OF cast iron, and Light wrought
iron railing surmounts the whole.
The butmentS, founded upon solid rock,
are built in the most substantial and durable
manner, OF 4 fine grey sandstone, Obtained IN
large blocks from the Government quarites AZ
Seneca, upon the Chesapeake and ONO Canai,
twenty-foUr miles from the city OF Wdshln9-
ton. The strength of this stone is seventeen
thousand pounds per so uare ihch.
This bridge is particularly remarkable Tor
the double duty which the arch performs.
While it supports roadway, forming Il beau
titul and much needed comm unicatlon, oy
which the traffic between the cities OF wash
ington and Georgetown Is carried over, the
water OF the Washington acqueduct Is con-
viewed in to the city of Washington through the
pipes of which the arch is composed. 10 guard
against all danger Of freezing, the pipes are
lined with slaves and resinous pine lumber,
three inches in thickness, leaving Clear wa
ter way in each rib of three and a half feet IN
diameter.
The flanges and bolts by which the pipes are
connected at the joints are covered with de-
coraiive mouldiugs, encircitd with foliage In
cast iron. The arch ribs spring from orna-
men tal bases, which distribute the pressure
over huge blocks Of granite set in the skew
back of the abu tments. The intersections OF
the beams in the frame work of the spandri!s
are covered with ornamental bosses, also OF
cast iron. The whole is Il model Of lightness
and elegance, being two hundred feet IN clear
span ana IOItJ I'VE AetL III HciaAI AZ eAu
water to the top of the parapet.
The central or GROWING pipes Of tho arch
bear the names of those who constrnct ted II,
viz: Capt. M. G.. Megs, u. S. Engineer; Il.
I. ID. Myers of Virginia, civil engineer and A.
& w. Denmead and sons, Of Baltimore, con-
tractors.
The abutments contain vaults, in which are
the connecting pipes and stop-cocks for regu
lating the flow and discharge of water, and il
the western abutments on the Georgetown side
one of the vaults serves as an engine room and
cor tains water pressure enginethe first, IL
is belle we'd. erected in this country.
This engine. drawing Its supply from the
ca-t iron street mains OF the Washington az ue
duct, pumps ten thousand gallons OF water
per hour into reservoir on tt heights OF
Georget own, a mile distant, and two hundred
aud four feet above the machine. This reser-
voir supplies that portion of Georgetown
which is above the level OF the great store ana
distributing reservoir Of the Washingto on eque-
duct
This aqueduct is among the foremost: Of
those monumental works of which America
can boast 1t has been constructed by the
General Government under the direction Of
Col. NJ. @. Meigs, distinguished officer of the
". S. Engineer Corps. Upon ii are other
works not less remarkable than this one :;
among Them he great granite arch, by which
the masonry aqueduct, nine feet III diameter,
crosses the CABIN John Greek, at height Of
one hundred and one feet above The bed OF the
stream. This arch Is built OF hewn granite, is
twenty fee; wide, fifty-Seyen feet three inches
rise, and, being two hundred and twenty 1eet
in clear span, is the largest stone arch in the
world.
The resident engineer upon this last-named
work was Mr. A. l.. Rives, of Virginia.
Had either of these bridges been constructed
in Great Britain, the public press would have
teamed with illustrations and descriI lions Of
them, and every reading man, woman and
child in Europe and America would nave Eeen
as familiar with their history az with that Of
the Menai Bridge or the "Great Eastern
while in Washington they are executed and
few but those who have bestowed upon them
the thought and toll necessary 10 their design
and construction, seem to know OF the exist
ence of such national achievements of science
and skill.