providing experience in operation demonstrates that such higher speeds
can be obtained with safety.

The speed of local trains between City Hall and 96th Street will
average about 15 miles an hour, while north of 96th Street on both the
West side and East side branches their speed will average about 18
miles an hour, owing to the greater average distance between local
stations.

As the result of careful consideration of various plans, the company's
engineers recommended that all the power required for the operation of
the system be generated in a single power house in the form of
three-phase alternating current at 11,000 volts, this current to be
generated at a frequency of 25 cycles per second, and to be delivered
through three-conductor cables to transformers and converters in
sub-stations suitably located with reference to the track system, the
current there to be transformed and converted to direct current for
delivery to the third-rail conductor at a potential of 625 volts.

[Illustration: OPERATING GALLERY IN SUB-STATION]

[Illustration: GENERAL DIAGRAM OF 11,000 VOLT CIRCUITS IN MAIN POWER
STATION]

Calculations based upon contemplated schedules require for traction
purposes and for heating and lighting cars, a maximum delivery of
about 45,000 kilowatts at the third rail. Allowing for losses in the
distributing cables, in transformers and converters, this implies a
total generating capacity of approximately 50,000 kilowatts, and
having in view the possibility of future extensions of the system it
was decided to design and construct the power house building for the
ultimate reception of eleven 5,000-kilowatt units for traction current
in addition to the lighting sets. Each 5,000-kilowatt unit is capable
of delivering during rush hours an output of 7,500 kilowatts or
approximately 10,000 electrical horse power and, setting aside one
unit as a reserve, the contemplated ultimate maximum output of the
power plant, therefore, is 75,000 kilowatts, or approximately 100,000
electrical horse power.

[Sidenote: _Power
House_]

The power house is fully described elsewhere in this publication, but
it is not inappropriate to refer briefly in this place to certain
considerations governing the selection of the generating unit, and the
use of engines rather than steam turbines.

[Illustration: OIL SWITCHES--MAIN POWER STATION]

The 5,000-kilowatt generating unit was chosen because it is
practically as large a unit of