In arc lamps with fixed parallel carbons of the Jablochkoff type (see Candle, Jablochkoff) a strip of carbon connects the ends of the carbons in the unused candle. This is necessary to start the current. Such strip is called an igniter. It burns away in a very short time when an arc forms producing the [...]

In a dynamo the wire which plays no part in generating electro-motive force. In a Gramme ring the wire on the inside of the ring is idle wire.

Poles of wire sealed into Crookes’ tubes, not used for the discharge connections, but for experimental connections to test the effect of different excitation on the discharge.

A method of using the absolute or attracted disc electrometer. (See Electrometer, Absolute.) The suspended disc and guard ring are kept at the same potential, which is that of one of the points whose potential difference is to be determined; the lower fixed disc is connected to the other of the points whose potential difference [...]

Coils in a dynamo, in which coils no electro-motive force is being generated. This may occur when, as a coil breaks connection with the commutator brush, it enters a region void of lines of magnetic force, or where the lines are tangential to the circle of the armature.

Bodies which become electric by friction. This was the old definition, the term originating with Gilbert. It was based on a misconception, as insulation is all that is requisite for frictional electrification, metals being thus electrified if held by insulating handles. The term is virtually obsolete; as far as it means anything it means insulating [...]

A symbol sometimes used to indicate current intensity. Thus Ohm’s law is often expressed I = E/R, meaning current intensity is equal to electro-motive force divided by resistance. C is the more general symbol for current intensity.