Galvanizing. The art of coating one metal with another, such, for instance, as immersing iron in molten zinc. Galvanometry. An instrument having a permanently magnetized needle, which is influenced by a coil or a wire in close proximity to it. Galvanoscope. An instrument, like a galvanometer, which determines whether or not a current is present in a tested wire. Generator. A term used to generally indicate any device which originates a current. German Silver. An alloy of copper, nickel and zinc. Graphite. One form of carbon. It is made artificially by the electric current. Grid. The metallic frame of a plate used to hold the active material of an accumulator. Gravity. The attraction of mass for mass. Weight. The accelerating tendency of material to move toward the earth. Gutta Percha. Caoutchouc, which has been treated with sulphur, to harden it. It is produced from the sap of tropical trees, and is a good insulator. Harmonic Receiver. A vibrating reed acted on by an electro-magnet, when tuned to its pitch. High E. M. F. A term to indicate currents which have a high voltage, and usually low amperage. Igniter. Mechanism composed of a battery, induction coil and a vibrator, for making a jump spark, to ignite gas, powder, etc. I. H. P. Abbreviation, which means Indicated Horse Power. Impulse. A sudden motion of one body acting against another. An electro-magnetic wave magnetizing soft iron, and this iron attracting another piece of iron, as an example. Incandescence, A conductor heated up by a current so it will Electric. glow. Induced Current. A current of electricity which sets up lines of force at right angles to the body of the wire through which the current is transmitted. Induction, Magnetic. A body within a magnetic field which is excited by the magnetism. Installation. Everything belonging to an equipment of a building, or a circuiting system to do a certain thing. Insulation. A material or substance which resists the passage of a current placed around a conductor. Intensity. The strength of a magnetic field, or of a current flowing over a wire. Internal Resistance. The current strength of electricity of a wire to resist the passage. Interrupter. A device in a wire or circuit for checking a current. It also refers to the vibrator of an induction coil.