bottom of the foundation of the building, great care was necessary to
avoid any settlement. Instead of wood sheathing, steel channels were
driven and thoroughly braced, and construction proceeded without
disturbance of the building, which is very tall.

At 125th Street and Lenox Avenue one of the most complicated network
of subsurface structures was encountered. Street surface electric
lines with their conduits intersect. On the south side of 125th Street
were a 48-inch water main and a 6-inch water main, a 12-inch and two
10-inch gas pipes and a bank of electric light and power ducts. On the
north side were a 20-inch water main, one 6-inch, one 10-inch, and one
12-inch gas pipe and two banks of electric ducts. The headroom between
the subway roof and the surface of the street was 4.75 feet. It was
necessary to relocate the yokes of the street railway tracks on Lenox
Avenue so as to bring them directly over the tunnel roof-beams.
Between the lower flanges of the roof-beams, for four bents, were laid
heavy steel plates well stiffened, and in these troughs were laid four
20-inch pipes, which carried the water of the 48-inch main. (See
photograph on page 49.) Special castings were necessary to make
the connections at each end. The smaller pipes and ducts were
rearranged and carried over the roof or laid in troughs composed of
3-inch I-beams laid on the lower flanges of the roof-beams. In
addition to all the transverse pipes, there were numerous pipes and
duct lines to be relaid and rebuilt parallel to the subway and around
the station. The change was accomplished without stopping or delaying
the street cars. The water mains were shut off for only a few hours.

[Illustration: SPECIAL RIVETED RECTANGULAR WATER PIPE, OVER ROOF OF
SUBWAY AT 126TH STREET AND LENOX AVENUE]