=Conductance.= The conducting power of a mass of material, varying according to its shape and dimensions. The cylindrical or round conductor is the best type for the conveyance of electric currents. =Conduction.= The transmission of electricity through an immobile medium, such as a wire, or rod, or a bar. =Conductivity.= Ability to conduct electric currents. The conductivity of a wire is its power to conduct or transmit a current. Glass has no conductivity, and it is therefore a non-conductor. =Conductivity, Variable.= The change in the conducting or transmitting powers of metals and substances under different temperatures. Hot metal conducts an electric current better than cold. A hot carbon-pencil in an arc-light conducts the current better than when the light is first started, for as it warms up under the influence of the arc-flame the current passes more freely. Five minutes after the current is turned on the lamps in the circuit give a steady light, and do not sputter as when they first start up. =Conductor.= Anything which permits the passage of electric current. The term conductor is a relative one, and, excepting a vacuum, there is probably no substance that has not some conductive power. Metals, beginning with silver, are the best conductors, liquids next, glass the worst. The ether, or air, is a conductor of sound and electric vibratory disturbances, but not in the same sense as the ground. The air conducts frictional electricity, while the ground acts as a conductor for the galvanic current, or “current electricity.” By this last term is meant electricity which flows continually, instead of discharging all at once, with an accompanying spark or flash. =Conductor, Overhead.= Overhead electric lines, wires or cables, for conducting current. Generally poles are erected for this purpose. =Conductor, Prime.= A cylindrical or spherical body with no points or angles, but rounded everywhere and generally of metal. If made of other material, such as wood, glass, or composition, its entire surface is rendered conductive by being covered with sheet-metal, such as tin-foil, gold-leaf or tinsel, applied to it with paste, shellac, or glue. A prime conductor should be mounted on an insulated stand; it is employed to collect and retain frictional electricity generated by a static machine. =Conductor, Underground.= An insulated conductor which is placed under the surface of the earth, passing through conduits. =Connect.= The act of bringing two ends of wire together, either temporarily or permanently. Bringing one end of a conductor into contact with another so as to establish an electric connection. =Connector.= A sleeve, with screws or other clamping device, into which the ends of wires or rods may be passed and held securely. A binding-post and spring-jack comes under this head.