34 STANDARD ELECTRICAL DICTIONARY.

Anisotropic. (adj.)

Unequal in physical properties, as in conduction and specific inductive

capacity, along various axes or directions. An anisotropic conductor is

one whose conductivity varies according to the direction of the current,

each axis of crystallization in a crystalline body marking a direction

of different conductivity. An anisotropic medium is one varying in like

manner with regard to its specific inductive capacity. In magnetism an

anisotropic substance is one having different susceptibilities to

magnetism in different directions. The term is applicable to other than

electric or magnetic subjects.

Synonym--AEolotropic.

Annealing, Electric.

Annealing by the heat produced by the passage of the electric current

through the body to be annealed. The object is clamped or otherwise

brought into a circuit, and a current strong enough to heat it to

redness, or to the desired temperature is passed through it.

Annunciator.

An apparatus for announcing a call from any place to another, as from a

living-room to an office in a hotel, or for announcing the entering of

any given room or window in a building protected by a burglar alarm.

A usual system comprises for each annunciator an electro-magnet. Its

armature is normally held away from its poles by a spring, and when in

that position a latch connected to the armature holds a little shutter.

When by a push-button or other device a current is sent through a

circuit which includes the electro-magnet the armature is attracted,

this releases the latch and the shutter drops. In dropping it displays a

number, letter or inscription which indicates the locality of the

push-button or other circuit-closing device. Often annunciators are

connected in circuit with a bell.

Fig. 14. ANNUNCIATOR.

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