*Intermeshing.* The meeting of the teeth of gears. *Intermittent.* Having periods of intermission. *Intermingle.* Mixing. Closely united. *Internal combustion.* A burning within a cylinder or chamber. *Insulated.* A conductor, or other material so coated as to prevent a current of electricity from passing, to or from the same through the substance so placed on it. *Invariably.* Constant; a uniform condition. *Journaled.* Held within a bearing so it may revolve. *Jump spark.* A system of igniting the carbureted air in an explosion engine, which consists in having a small separation between the points in a conductor, and in using a current with a sufficiently high voltage to jump across the gap thus made. *Lapped.* A term used to designate the smoothing out of engine cylinders or of any metal too hard to be handled by the lathe. *Lateral.* Across; longitudinal, means lengthwise, and lateral is the term to express the direction at right angles to the longitudinal line. *Lock nut.* Any device which will prevent the nut from turning loose after being tightened. *Longitudinal.* The long way across an article. *Low tension.* A current which has a low voltage. *Lubricant.* Any substance which, when applied to moving parts, will decrease friction. *Lubrication.* The act of applying a lubricant. *Magnet.* A metallic substance which has power to attract iron or steel. *Magneto.* A permanent magnet and a revolving armature for generating a current. *Magnetic pull.* The action exercised by a magnet of attracting or repelling. *Magnetic field.* The space or region near a magnet or charged wire. *Make and break.* In igniting systems a piece of mechanism which makes and breaks a circuit, so as to produce a spark each time when the wires are separated.