Snap Switch

A switch so arranged that it will quickly make a break.


The apparatus at one end of a line actuated by a key at the other end of the line.

Spark Coil

A coil, to make a spark from a low electro-motive force.

Spark, Electric

The flash caused by drawing apart the ends of a conductor.

Specific Gravity

The weight or density of a body.

Static Electricity

Generated by friction. Also lightning. Any current generated by a high electro-motive force.

Strength of Current

The quantity of electricity in a circuit.


Operating together; acting in unison.


The end of any electric circuit or of a body or machine which has a current passing through it.

Thermostat, Electric

An electric thermometer. Usually made with a metal coil which expands through the action of the electricity passing through it, and, in expanding, it makes a contact and closes a circuit.


The induction coil with a high initial E. M. F. changes into a low electro-motive force.


A standard of light, heat, electricity, or of other phenomena.


A space from which all matter has been exhausted.


Mechanism for making and breaking circuits in induction coils or other apparatus.


The unit of electro-motive force.


Electro-motive force which is expressed in volts.


A term applied to electric currents and devices.


An apparatus for showing the difference of potential, or E. M. F. in the term of volts.


The unit of electrical activity. The product of amperes multiplied by volts.

Watt Hour

One watt maintained through one hour of time.

Waves, Electric Magnetic

Waves in the ether caused by electro-magnetic disturbances.


The radiation of invisible rays of light, which penetrate or pass through opaque substances.

Yoke, or Bar

A soft iron body across the ends of a horseshoe magnet, to enable the magnet to retain its magnetism an indefinite time.

Zinc Battery

A battery which uses zinc for one of its elements.