nto the well through a drain
connecting to the tunnel.

Each well is then provided with a pumping outfit; but in the case of
these wells and in other locations where it is necessary to maintain
pumping devices, it has not been possible to employ a uniform design
of pumping equipment, as the various locations offer different
conditions, each employing apparatus best suited to the requirements.

In no case, except two, is an electric pump employed, as the
employment of compressed air was considered more reliable.

The several depressions at which it is necessary to maintain a pumping
plant are enumerated as follows:

No. 1--Sump at the lowest point on City Hall Loop.

No. 2--Sump at intersection of Elm and White Streets.

No. 3--Sump at 38th Street in the Murray Hill Tunnel.

No. 4--Sump at intersection of 46th Street and Broadway.

No. 5--Sump at intersection of 116th Street and Lenox Avenue.

No. 6--Sump at intersection of 142d Street and Lenox Avenue.

No. 7--Sump at intersection of 147th Street and Lenox Avenue.

No. 8--Sump at about 144th Street in Harlem River approach.

No. 9--Sump at the center of the Harlem River Tunnel.

No. 10--Sump at intersection of Gerard Avenue and 149th Street.

In addition to the above mentioned sumps, where pumping plants are
maintained, it is necessary to maintain pumping plants at the
following points:

Location No. 1--At the cable tunnel constructed under the
Subway at 23d Street and Fourth Avenue.

Location No. 2--At the sub-subway at 42d Street and Broadway.

Location No. 3--At the portal of the Lenox Avenue extension
at 148th Street.

Location No. 4--At the southerly end of the Harlem River tube.

Location No. 5--At the northerly end of the Harlem River tube.

Location No. 6--At the portal at Bergen Avenue and 149th Street.

In the case of the No. 1 sump a direct-connected electric
triple-plunger pump is employed, situated in a pump room about 40 feet
distant from the sump pit. In the case of Nos. 2, 4, and 7 sumps,
automatic air lifts are employed. This apparatus is placed in those
sump wells which are not easily accessible, and the air lift was
selected for the reason that no moving parts are conveyed in the
air-lift construction other than the movable ball float and valve
which control the device. The air lift consists of concentric piping
extending several feet into