The pilot and transcript. [volume] (Baltimore, Md.) 1840-1841, 1840-12-07
CROTON AQTEDUCT.

To the Editor Ofthe United States Gazette.
The magnificent work known as the Sing
Sing Aqueduct Bridge is now complete, and is
said to be, with one exception, the largest arch
in the United States. In May, 1888, the first
| stone OF the abntments was laid, and the idea
that stone by stone, the structure was to be rails
ed so feet above that level, causedl many of the
neighboring people to predict very confidently,
that it never woald be completed. The abut-
ments on both sides were laid upon the solid
rock, and built against the rock so that the i'm
mense pressure Of that great mass of masonry is
received upon the foundation as immoveable as
the Esround world ITSELF
The abutments were commenced 261 feet wid9
and the whole work has batter of in "a, max
ing the width at the top under the coping about
I feet less. The arch springs from point p
feet above the foundation, and has span of IS
feet, and rise of 33 feet. The original pl IA
contemplated span of 40 and rise of % feet,
but in order to place the abutments firmly on the
rock on both sides, it was found necessary to in
crease it to its present dimensions. This varia-
ton both mcreasedits strength and improved its
beauty. The arch is a ':curve OF FIVE centres p
that is, it is composed of 3 arcs SO arranged
that at the points of junction, the radii of the
two adjoining arcs shall coincide. This pre-
vents any abrupt change of direction in passing
from one arch to another The arch-stones have
a depth OF feet at the springing line, decreas-
ing regularly in depth to the crown or highest
point, where there are feet The system of
centering, upon which the arch stone rested dur
ing the construction contained more than $4,000
feet (broad measure) of timber, chilly white
pine, and is of the most perfect systems in the
world. PIlasters projecting feet from the face
of the work, and having width OF 10 feet, give
an appearance of greater strength and solidity,
as well as relieve the monotOnous appearance OF
the otherwise uniform face.-Large openings are
r IL. Ill. 6 al
for the purpose of relieving it of part of the great
weight which would otherwise rest upon it. A
passage is effected into these openings by means
of square wells left in the thickest part of the
masonry, at the pilasters. Awater table projects
10 inches from the face OF the wall Immediately
over the arch. Some persons think that an ap- |
pearance of greater lightness would have been
given if this water table had been placed about |
II to 2 higher
The small arch over the road called the Via
duet arch has a span Of 20 feet, and rise of 5 |
feet. with abutlnents 5 IL feet high, leaving a |
passage of I3 feet in height. This arch has the |
same general form as the large one. The space !
between these two arches, distance of 12S feet |
as well as the space south of the main arch of
about / 80 feet; is filed up with closely laid |
stone wall On the wall, and over the arches,
the Aqueduct is built in the following manner:
First, Concrete, that is, mixture OF cement,
finely broken stone and sand, is laid to depth
of 1-2 feet, and shaped to receive the inverted
arch, which consists of two courses OF brick.
This arch has a span of 6 "a feet, and versed
side OF inches. Between these courses OF brick
over the main arch, in order more perfectly to-
ensure the prevention cf leaking, iron plates are
placed 5 of an inch thick, end cemented toge-
Their with iron cement. On each OF this arch
walls 12 feet thick are built OF stone, lined on
the inside with brick. In these walls, running
the whole length of the work, distances of
450 feet, longitudinal openings are left inches
wide, for the purpose of interposmg stratum of
air between the water and the atmosphere, as
being the best protection which could be afforded
against the frost.
These opening S, as well as the large ones in
the spandrels before referred to, also serve to
conduct away any water which might find its
way through the masonry, though the last is
not very likely TO take place. Over the space
between the walls last mentioned, an arch of
brick inches thick is sprung, and the whole
covered with earth to the depth of about feet
to protect the work from injury by frost or any
other cause. 1t is the present intention to fin
ish by covering it with thick sod. A coping
of cut stone of one foot in thickness extends
the whole length giving finished appearance |
to the whole structure. Il
The dimensions Of the passage way for the