Washington sentinel. [volume] (Washington [D.C.]) 1853-1855, 1854-01-20
@ 0 m m unifatf6.
For the Sentinel.

Saeyf ahu requires some nOtlce.
IL IS evidently written by an advocate of the
Rock Creek scheme, and quotes Col. Hughes
report in regard to the difficulties of bringing
water from the Great Falls. 1t also quotes
Captain Meigs' report, taking passage in
which ne speaks of the costly nature of the
works, ne was obliged to devise, for bringing
cessarily placed near the level of the river and
exposed to its floods, and applying it very I'M
fairly to the project from the Great Falls, which
has been under the authority vested in him by
Congress, adopted by the President, and which
owing to the great descent of the river at its
point of beginning, is, in very short distance,
out of reach Of its freshets.
Had the writer been disposed quote fairly,
he would have taken the following passage
The traveller ascending the bank of the Poto-
mac from Georgetown TO the Great Falls, would
conclude that more unpromising region for the
construction OF an aqueduct could not be found
Supported by high walls against the face of jagged
and vertical precpices, in continual danger of
being undermined by the foamng torrent which
bolls below, the canal is a monument Of the ener-
gy and daring of our engineers. The route seems
occupied, and no mode of bringing in the water
except by iron pipes secured 10 the rocks or laid
in the bed of the canal seems practicable Such
We're my own impressions, and though / knew,
that in this age, with money, any achievement of
engineering was possible. / thought the survey
would be needed only to demonstrate by figures
and measures the extravaganza of such work.
But, when the levels were applied TO the
ground, found, 70 my surprise and qualification,
that the rocky precpces and difficult passages
were nearly all below the line which, allowing q
uniform grade, would naturally be selected for our
conduit and that, instead of demonstrating the
extravaganza of the proposal, it became my duty
TO devise work presenting no considerable diff
los ondn of Ordyn
hibilion of any triumphs Of science or skill
"lndeed, the nature Of the country is such as
to present less than the ordinary difficulties 10 be
expected in such an undertaking. There are sew
eral tunnels of an average length of only 220 feet
but three bridges, and only one Of these large
enough to make its erection an object of ambition
to an engineer The line runs on the slope Of the
hills which is generally moderate and such as to
afford choice Of ground. 1t has been located so as
TO conform to the surface, and requires very light
excavation and embarkment. As will be evident
from the accompanying maps, it is very direct
line, Of remarkably easy curves, much less
crooked than the line we were compelled to adopt
on Rock Creek; though longer with fewer
bridges, and those, except in one instance, less
costly The distance, in right line from the be-
ginning Of the conduit TO the north end Of the
Georgetown aqueduct, is eleven and three quar-
tiers miles; the length Of the conduit is about
fourteen miles, including the reservoirs and the
pipe, to this same point. And then he would not
have been able TO say these facts and admissions
are sufficient 10 cause prudent men TO pause &c.
Since Colonel Hughes report was made, the
experience of Boston and New York has
shown that much larger supplies of water are
needed, even in those northern cities, than he
calculated upon. Boston using, instead Of
282 gallons daily to each inhabitant, on some
days nearly 80 gallons.
The question of supply is fully discussed in
Captain Meigs' report, and reasons sufficient
are given for adopting plan which, at mod
crate expense, gives very ample one. 1t is
there shown that an aqueduct, to make the
best use of Rock Creek, including the cost of
distribution to public buildings, Navy-Ya ard,
DC, with proper storage and reservoirs, will
cost, not 100000, but one and quarter mil
IONS
This difference results from providing larger
reservoirs, a larger aqueduct and nearly
100000 worth Of pipes to the various public
which were not provided for at
all in Colonel Hughes estimate
But, after all, the supply from Rock Creek is
not reliable, and those who have lived on its
banks, near Georgetown, will testify that during
the past summer it has been almost lost in the
pebbles of its bed.
Another party desires to lay an iron pipe
from the falls, thinking that this will save great
expense in grading.
delivering water in a reservoir at height not
much below the source, and drawing it off at
the level of Pennsylvania avenue, for example:
A three foot pipe from the Great Falls would
deliver on Pennsylvania avenue vast quantity
Of water, but not much on the attic floor Of
the Capitol.
Exclusive Of digging and covering from FROST
D single three foot pipe will cost as quite as
much as the brick arch of the aqueduct, nine
feet in diameter, and will not deliver one ninth
as much water
The digging and grading necessary to lay
one pipe at such depth in the rocky soil as
TO be secure from frost, will cost far more than
these persons suppose. If the top of the pipe
be three feet under ground, as it must be to be
secure from Frost it will require six feet of ex-
cavation. And it would take more than nine
three feet pipes to deliver at the distributing
reservoir the same quantity as the nine feet
conduit.
Indeed, to supply a reservoir in Washington,
one hundred and torty-fve feet above tide, by
IRON pipes, with the same quantity Of water as
will be delivered by the nine foot aqueduct
would cost nearly nine times as much. These
assertions will surprise, but little calculation
and study of the subject will bring any engi.
neer to this conclusion.
New York built her aqueduct of masonry,
and very extensively. Boston did the same
On more economical plan, after several years
Of study, and comparison of projects from
many engineers. Albany has since followed
the example. Is it likely that all the eminent
engineers consulted on these great works have
been wrong as to material
Is it worth while to build, as these cities have
all. done-a work which in ten years will be in
sufficient and require enlargement, or entire
rebuilding?
Are these people aware that iron is liable to
rust? What iron pipe now laid underground
will be capable Of resisting the pressure of
water one hundred years hence? Masonry aque-
ducts, properly constructed, and covered from
frost, neither rust nor decay; and some near
two thousand years old still continue to supply
the cities which built them.
A word as to the danger Of injury to the
Washington aqueduct from the Great Falls by
foods.
The dam crossing the river will be the only
- II Al n - n