A chemical compound whose molecule contains only two elements, such as water (H2 0), lead oxide (Pb 0), and many others.

The method followed in winding resistance coils to prevent them from creating fields of force. The wire is doubled, and the doubled wire starting with the bend or bight is wound into a coil. The current going in opposite senses in the two lays of the winding produces no field of force.

In polarized relay the adjustment of the tongue to lie normally against one or the other contact.

A bell operated by a relay circuit.

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.

A bell which by drop-shutter or other indicator connected in circuit with it, indicates its number or other designation of its call.

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.

A bell rung by electricity. Generally it is worked by a current exciting an electro-magnet, attracting or releasing an armature which is attached to the vibrating or pivoted tongue of the bell. It may be worked by a distant switch or press-button, q. v., ringing once for each movement of the distant switch, etc., or [...]

An electric bell, whose magnet is wound differentially so as to prevent sparking.

A gong-shaped bell, whose clapper and general mechanism is within its cavity or behind it.