Bell, Electro-mechanical.
A bell which has its striking train operated by a spring or descending
weight, and which train is thrown into action by the release of a detent
or equivalent action by the closing of an electric circuit. It rings for
any given time after being started.
Bell, Indicating.
A bell which by drop-shutter or other indicator connected in circuit
with it, indicates its number or other designation of its call.
Bell, Magneto.
An electric bell operated by the alternating current from a magneto
generator. It has a polarized armature and no circuit breaker. The
armature is attracted first in one direction and then in the other, as
the current alternates and reverses the polarity of the electro-magnet.
Bell, Relay.
A bell operated by a relay circuit.
Bias.
In polarized relay the adjustment of the tongue to lie normally against
one or the other contact. (See Relay, Polarized.)