orm of the first car. The switches
which open and close the power circuits through motors and rheostats
are called contactors, each comprising a magnetic blow-out switch and
the electro magnet which controls the movements of the switch. By
these contactors the usual series-multiple control of direct-current
motors is effected. The primary or control circuits regulate the
movement, not only of the contactors but also of the reverser, by
means of which the direction of the current supplied to motors may be
reversed at the will of the motorman.

[Illustration: APPARATUS UNDER COMPOSITE MOTOR CAR]

The photograph on this page shows the complete control wiring and
motor equipment of a motor car as seen beneath the car. In wiring the
cars unusual precautions have been adopted to guard against risk of
fire. As elsewhere described in this publication, the floors of all
motor cars are protected by sheet steel and a material composed of
asbestos and silicate of soda, which possesses great heat-resisting
properties. In addition to this, all of the important power wires
beneath the car are placed in conduits of fireproof material, of which
asbestos is the principal constituent. Furthermore, the vulcanized
rubber insulation of the wires themselves is covered with a special
braid of asbestos, and in order to diminish the amount of combustible
insulating material, the highest grade of vulcanized rubber has been
used, and the thickness of the insulation correspondingly reduced. It
is confidently believed that the woodwork of the car body proper
cannot be seriously endangered by an accident to the electric
apparatus beneath the car. Insulation is necessarily combustible, and
in burning evolves much smoke; occasional accidents to the apparatus,
notwithstanding every possible precaution, will sometimes happen; and
in the subway the flash even of an absolutely insignificant fuse may
be clearly visible and cause alarm. The public traveling in the subway
should remember that even very severe short-circuits and extremely
bright flashes beneath the car involve absolutely no danger to
passengers who remain inside the car.

The photograph on page 120 illustrates the control wiring of the
new steel motorcars. The method of assembling the apparatus differs
materially from that adopted in wiring the outfit of cars first
ordered, and, as the result of greater compactness which has been
attained, the aggregate length of the wiring has been reduced