An apparatus used in exploring a field of electro-magnetic radiations.
It is a piece of copper wire 2 millimeters (.08 inch) in diameter, bent
into an almost complete circle 70 millimeters (.28 inch) in diameter,
with terminals separated by an air gap. This is moved about in the
region under examination, and by the production of a spark indicates [...]

A system of relay connection, q. v., by which a bell is made to continue
ringing after the current has ceased coming over the main line. It is
designed to prolong the alarm given by a magneto call bell, q. v., which
latter only rings as long as the magneto handle is turned. A vibrating
electric bell (see Bell, [...]

A coil, similar to a magnetizing coil (see Coil, Magnetizing), used for
investigating the electro-magnetic circuit and for similar purposes. If
placed around an electro-magnet and connected with a galvanometer, it
will produce a deflection, owing to a momentary induced current, upon
any change in the magnet, such as removing or replacing the armature. It
is useful in determining the [...]

(a) A small magneto-generator for producing a current for heating the
wire in an electric fuse of the Abel type (see Fuse, Electric), and
thereby determining an explosion.
(b) The term may also be applied to a small frictional or influence
machine for producing a spark for exploding a spark fuse.

(a) The increase in volume of a condenser, when charged
electrostatically. A Leyden jar expands when charged, and contracts when
discharged.
(b) The increase in length of a bar of iron when magnetized.
This is more properly called magnetic expansion or magnetic elongation.

The number expressing the proportional increase in size, either length,
area or volume, of a substance under the influence generally of heat.
There are three sets of coefficients, (1) of linear expansion, (2) of
superficial expansion, (3) of cubic expansion or expansion of volume.
The first and third are the only ones much used. They vary for different
substances, and [...]

The outflowing current of electric osmose. (See Osmose, Electric.)

A generator used for exciting the field magnet of a dynamo. In
alternating current dynamos, e. g., of the Westinghouse type, a special
dynamo is used simply to excite the field magnet. In central station
distribution the same is often done for direct current dynamos.

The susceptibility of a nerve or muscle to electric current shown by the
effect produced by its application.

The same as Faradic excitability, except that it refers to the effects
of the current from a galvanic battery.