Float Feed-An arrangement by which the flow of a liquid is regulated by a valve operated by a float.

Flooding-An excess of gasolene or other liquid fuel in an engine. Fly-wheel—The large wheel at the end of the shaft used to carry the momentum of the shaft beyond dead centre and to minimize vibration.

Four-cycle-The operation of a motor in which an explosive impulse occurs only on every other revolution of the fly-wheel or on every fourth stroke.

Friction Clutch-A clutch in which the power or motion is held and transmitted by frictional resistance.

Gap The space through which a spark will pass between two electrodes or terminals.

Gasket A ring of material, or packing, placed between two surfaces to render the joint tight.

Gate Valve-A valve which operates by a gate or partition that rises and falls in a groove or guide, thus giving a full opening; a fullway valve.

Gauge An instrument for measuring anything.

Gear-A cog-wheel. A combination of cog-wheels. A device for transmitting power, speed, or direction through a combination of cog-wheels or 'gears.'

Gear Pump-A form of rotary pump in which the water is sucked in and forced out by the revolution of two interlocking gears. Generator—An appliance for generating gas from liquid fuel and air. An instrument for generating electricity.

Gland—A ring, or thimble, of metal used to hold packing in position. Globe Valve-A valve which operates by a circular or globular valve. seating by turning down a threaded stem or spindle.

Governor-A device for regulating power, speed, or flow. In connection with gasolene motors, a device for regulating the speed of the motor within certain limits.

Gravity Feed-The feeding or flowing of oil by gravity alone. Gravity Oiler-An oiler operated by gravity. Not a force-feed oiler. Grounding-Connecting one wire from an electrical generator to the ground or to the frame of the motor and using the same in place of a complete wire to the other electric terminal.

Hammer Break-A form of breaker, or interrupter, which acts like a hammer by striking upon another piece of metal.

Hammer Vibrator-A vibrator constructed heavily to give stronger and slower vibrations than other forms.

Hanger Bolt-A lag-screw with a threaded end in place of a square head and onto which a nut may be screwed after the screw itself is in place, thus avoiding removing the screw from the wood in order to remove the object held in place by the screw head. Helical Gear—A gear wheel with the teeth cut at a certain slant or curve, which forms the part of a helix or coil.

Helical Spring—A spring made in the form of a helix; a coil spring. High Tension-A form of electrical discharge of high amperage. The induced current in an induction coil. The secondary

current.

Hit-and-miss Governor-A governor which regulates the speed of an engine by allowing the valves to lift or remain closed through the action of an arm or blade which operates at normal speed but which misses when the desired speed is exceeded.

Horse-power-The power required to lift 33,000 pounds one foot in one minute.

Hot Tube-A form of igniter in which the charge of gas is exploded by the use of a tube kept at red heat.

Hunting-The irregular action of a governor causing an engine to slow up or increase its speed at intervals.

Hydrometer-An instrument for testing the specific gravity of liquids.

Igniter-Any device for igniting the explosive charge of gas.
Igniting Device-Same as Igniter.

Ignition-The process of igniting the charge of gas.

Ignition Plug-A plug inserted in the cylinder and which carries the electric spark used in igniting the charge; a spark plug.

Indicator-A machine for ascertaining the action of an engine by means of a tracing on a card.

Indicator Card-The card on which an indicator forms a tracing to show the action of a gasolene motor.

Inductance The power of inducing, or generating, electricity in a coil of wire by passing an electrical current through another coil close to but not in contact with the other.

Induction Coil-A coil for generating induced electricity. Inertia-The tendency of an object to remain stationary when at rest and which must be overcome before it starts to move.

Inertia Governor—A governor that acts through inertia.

Inlet Valve-The valve which admits the charge of gas to an engine's

cylinder.

Insulation-The protection, or covering, of electrical conductors to prevent the escape of electricity.

Insulator-Anything which prevents the electricity from escaping from a conductor.

Intake The opening through which the fresh gas is taken into the cylinder.

Intake Stroke-The stroke of an engine's piston which draws a charge of gas into the cylinder. The suction stroke.

Jacket-The portion of a motor covering the cylinder and separated from it by a passage for the circulation of water or other cooling liquid.

Jig-A device by which any machined article may be accurately duplicated.

Journal-A bearing on a shaft.

Journal Box-The casing holding a journal.

Jump Gap The space through which an electric spark will jump. Jump Spark-A spark of high-tension electricity which is caused by separating the electrodes or terminals of a circuit, thus causing the electricity to leap or jump across, producing a hot spark.

Key-A square piece of metal inserted between a wheel, or similar object, and a shaft and fitting into recesses in each to prevent turning or looseness of the two parts.

Keyway-The slot or recess into which a key fits.

Kicking Backfiring or premature explosions causing the motor to reverse its motion when starting or to "kick" backwards. Kiss Spark-A form of make-and-break ignition in which the contact points approach gradually, press firmly together, and separate instantly. Also called Butt Spark.

Lag-screws-Heavy wood screws provided with a square bolt head. Lead-The advance or timing of a spark to cause ignition before the limit of the compression stroke, causing the explosion to exert its greatest force just as the piston passes dead centre.

Lever-A rod or arm for increasing, transmitting, or controlling power or motion.

Liners Thin pieces of metal for reducing or enlarging the space between two pieces of metal.

Lock Nut-A nut screwed onto a bolt above the regular nut to prevent the latter from working loose.

Lock Washer-A washer, or ring, with one side cut through and the ends slightly turned up or sprung apart. Used to place under a nut on a bolt. The turned-up edges prevent the nut from loosening or working off by the friction of the ends bearing on the under surface of the nut.

Lost Motion-Any looseness or motion which accomplishes no useful purpose and detracts from power or speed.

Low Tension-The primary electrical current either direct from a generator or battery or after being passed through a primarywound coil.

Lubricant-Any substance that lubricates or reduces friction between moving parts.

Lubricator-Any device for distributing a lubricant.

Lug-A metal projection for attaching to another object or for bearing against another piece.

Magneto-A machine for generating electricity by means of an armature revolving, or oscillating, between two permanent mag

nets.

Make and Break—A system of ignition in which the spark is produced by alternately making and breaking an electrical current. Manifold-The common outlet of several pipes or tubes. Manometer-A gauge or instrument for determining the pressure of gases.

Mechanical Equivalent. The power contained in a gaseous body and which must be accounted for, either as heat abstracted from it or as some form of mechanical energy. A deduction from the law that nothing in nature can be lost or wasted.

Mechanical Oiler-An oiler or lubricator operated by mechanical

means.

Mechanical Valve-A valve operated by mechanical means.

Misfire-The failure of a compressed charge to ignite and explode.

Momentum-The tendency of an object to continue in motion after the power required to move it has been stopped.

Motor-Any machine for producing power or for transforming natural forces to mechanical motion.

Muffler-A device for quieting or silencing the noise of the exhaust.

Needle Valve-A valve formed by a pointed rod bearing against the circumference of a small hole.

Nipple-A short piece of pipe threaded at both ends.

Offset Cylinder-A cylinder so placed that its centre is at one side of the centre of the crank shaft.

Offset Crank—A crank placed so that its centre is out of line with the centre of the cylinder.

Ohm-A unit of electrical measurement denoting resistance dependent upon diameter, length, and material of the electric conductor. Analogous to "friction."

Oil Feed-A device for distributing oil.

Oil Pump-Any device for pumping oil.

Otto Cycle-Four-cycle. So called because the Otto engine was the first to successfully adopt this system of operation.

Packing-Any material used to prevent leakage around a moving part or between the two surfaces of a joint.

Packing Gland—A piece of metal which presses the packing into
place and is held by a threaded screw or other device.
Packing Nut-A nut used to hold packing in place.
Pein-The end of a hammer used for striking.

Peining-Hammering or stretching a piece of metal by use of the "pein."

Pendulum Governor-A governing device in which the speed is regulated by the swing of a pendulum instead of by centrifugal force.

Phases-See Cyclic Phases.

Pick Blade The small blade or pick of metal which lifts the valve in a pick-blade governor.

Pick-blade Governor-A governor that regulates the speed of a motor by means of a blade or pick which lifts or misses the valve stem under excessive speeds.

Pillow Block-A block or stand supporting a bearing or journal. Pinion-A small cog-wheel. Properly a wheel with pins or posts in place of cogs.

Piston-A sliding object within a cylinder; a plunger.

Piston Pin-The pin which holds the connecting rod to a piston. Piston Ring-Metal rings fitted loosely around grooves in a piston which by spring of the metal form a gas-tight joint with the cylinder walls.