New York City Tours

parated from the others by its location in an enclosed compartment, the walls of which are brick and soapstone. The general construction of the switch is illustrated by the photograph on page 94. [Illustration: CROSS SECTION SUB-STATION NO. 14] [Illustration: INTERIOR OF SUB-STATION NO. 11] [Illustration: LONGITUDINAL SECTION SUB-STATION NO. 14] Like all current-carrying parts of the switches, the bus bars are enclosed in separate compartments. These are constructed of brick, small doors for inspection and maintenance being provided opposite all points where the bus bars are supported upon insulators. The photographs on pages 95 and 96 are views of a part of the bus bar and switch compartments. [Illustration: TWO GROUPS OF TRANSFORMERS] The oil switches and group bus bars are located upon the main floor and extend along the 59th Street wall of the engine room a distance of about 600 feet. The main bus bars are arranged in two lines of brick compartments, which are placed below the engine-room floor. These bus bars are arranged vertically and are placed directly beneath the rows of oil switches located upon the main floor of the power house. Above these rows of oil switches and the group bus bars, galleries are constructed which extend the entire length of the power house, and upon the first of these galleries at a point opposite the middle of the power house are located the control board and instrument board, by means of which the operator in charge regulates and directs the entire output of the plant, maintaining a supply of power at all times adequate to the demands of the transportation service. [Illustration: MOTOR-GENERATORS AND BATTERY BOARD FOR CONTROL CIRCUITS--SUB-STATION] [Illustration: 1,500 K. W. ROTARY CONVERTER] [Sidenote: _The Control Board_] The control board is shown in the photograph on page 97. Every alternator switch, every selector switch, every group switch, and every feeder switch upon the main floor is here represented by a small switch. The small switch is connected into a control circuit which receives its supply of energy at 110 volts fr