Chapter XIX: Appendix: A Dictionary of Electrical Terms and Phrases (2)

=Crystallization, Electric.= Under proper conditions many substances and liquids take a crystalline form. When such action is brought about by means of electricity the term electric crystallization may be applied to the phenomenon. A solution of nitrate of silver, when decomposed by a current, will give crystals of metallic silver. A solution of common salt or brine, when electrically decomposed, will produce sodium and chlorine. The sodium appears at the leading-out electrode and readily unites with carbonic-acid gas, which is injected into the apparatus. The result of the combination is carbonate of soda, one of the most important products of the alkali industry.

=Current, Alternating.= A current flowing alternately in opposite directions. It is a succession of currents, each of short duration and of direction opposite to that of its predecessor. Abbreviation, A-C.

=Current, Amperage.= The volume of electricity passing through any circuit per second, the flow being uniform.

=Current, Constant.= An unvarying current. A constant-current system is one in which the current is uniformly maintained--for example, in electric light, power, and heat plants.

=Current, Continuous.= A current of one direction only, or the reverse of an alternating current.

=Current, Direct.= A current of unvarying direction, as distinguished from the alternating. Abbreviation, D-C.

=Current Distribution, Uniform.= A steady current; a current whose density in a conductor is always the same at all points.

=Current, Induced.= A current caused by electro-dynamic induction.

=Current, Low Potential.= A current of low pressure.

A term applied to low electro-motive force.

=Current, Make-and-break.= A current which is continually broken or interrupted and started again. The term is applied only where the interruptions occur in rapid succession, as in the action of an induction-coil or pole-changer.

The alternating current.

=Current-meter.= An apparatus for indicating the strength of a current, such as an ammeter.

=Current, Oscillating.= A current periodically alternating.

=Current, Periodic.= A current with periodically varying strength or direction. A current alternating periodically.

=Current, Polarizing.= A current which causes polarization.

=Current-reverser.= A switch or other contrivance for reversing the direction of a current in a conductor.

=Current, Undulating.= A current whose direction is constant but whose strength is continuously varying.

=Currents, Eddy.= Useless currents in an armature, in the pole pieces, and in the magnetic cores of dynamos and motors. They are created by the high speed of the armature in its rotation, or by other electric currents induced by the armature’s motion through magnetic fields.

=Currents, Faradic.= Induced currents. They take their name from Michael Faraday, the original investigator of the phenomena of electro-magnetic induction. The secondary or induced electro-magnetic currents and their accompanying phenomena.

A series of alternating electro-static discharges from influence machine, such as the Holtz and Wimshurst.

The simple and commonly understood Faradic currents are those produced in the medical battery, and used in medical therapeutics.

=Currents, Foucault.= A form of currents produced in revolving armature-cores; sometimes called eddy currents. They are useless.

=Currents, Harmonic.= Currents which alternate periodically, and vary harmonically. Currents which vibrate at certain pitches, as, for instance, the currents in wireless telegraphy. Two instruments must be tuned to the same pitch in order to be responsive. Thus an instrument sending out waves of 70,000 vibrations cannot be recorded by one tuned much below or above the same number.

Sound waves of sympathetic or harmonic vibrations.

=Currents, Positive.= (_See_ Positive Currents.)

=Cut-in.= To electrically connect a piece of mechanism or a conductor with a circuit.

=Cut-out.= The reverse of the cut-in. To remove from a circuit any conducting device. The cut-out may be so arranged as to leave the circuit complete in some other way.

An appliance for removing a piece of apparatus from a circuit so that no more current shall pass through the former.

=Cut-out, Automatic.= A safety device for automatically cutting out a circuit to prevent accident or the burning-out of an apparatus, due to an overload of current. It is worked by an electro-magnet and spring. An overload of current causes a magnet of high resistance to draw an armature towards it, and this, in turn, releases the spring of the cut-out device. Sometimes a strip or wire of fusible metal is employed which is in circuit with a switch. The excess of current fuses the metal, and the broken circuit releases a spring-jack, which, in turn, breaks the circuit.

=Cut-out, Safety.= A block of non-conducting material, such as marble, slate, or porcelain, carrying a safety-fuse or plugs. In these is enclosed a piece of fusible wire, which burns out or melts and breaks the circuit before the apparatus is damaged.

=Cut-out, Wedge.= A cut-out operated by a wedge, such as a spring-jack or the plugs at the end of the flexible wires on the switch-boards of telephone exchanges.

D

=Damper.= A frame of copper on which the wire in a galvanometer is sometimes coiled. It acts to check the needle oscillations.

A brass or copper sheathing or tube placed between the primary and secondary coils of an induction-coil to cut off induction and diminish the current and potential of the secondary circuit. When the tube is drawn out gradually the induction increases. It is commonly used in medical coils to adjust their strength of action.

=D-C.= An abbreviation for direct current.

=Dead Earth.= A fault in telegraph and telephone lines which consists in the ground-wire being improperly grounded, or not fully connected with the earth.

=Dead Turns.= A term applied to the ten to twenty per cent. of the convolutions or turns of wire on an armature which are considered to be dead. There are supposed to be about eighty per cent. of the turns on an armature that are active in magnetizing the core; the balance are outside the magnetic field and are termed dead, although they are necessary to the production of electro-motive force.

=Dead Wire.= A wire in the electric circuit through which no current is passing.

A disused or abandoned electric conductor, such as a telegraph wire, or a wire which may be in circuit, but through which at the time of speaking no electrical action is taking place.

=Death, Electrical.= Death resulting from an electric current passing through the animal body--electrocution; accidental death by electric shock; premeditated death through bringing the body in direct contact with conductors carrying high electro-motive force. High electro-motive force is essential, and the alternating current is most fatal.

=Decomposition, Electrolytic.= The decomposition or separation of a compound liquid into its constituents by electrolysis. The liquid must be a conductor or electrolyte, and the decomposition is carried on by means of electricity.

The conversion of two or more chemicals into a new compound or substance.

=Deflection.= In magnetism, the movement of the needle out of the plane. It is due to disturbance, or to the needle’s attraction towards a mass of iron or steel or another magnet.

=Demagnetization.= The removal of magnetism from a paramagnetic substance. The process is principally in use for watches which have become magnetized by exposure to the magnetic field surrounding dynamos or motors.

=Density, Electric.= The relative quantity of electricity, as a charge, upon a unit area of surface. It may be positive or negative.

Surface density, as the charge of a Leyden-jar.

=Depolarization.= A term applied to the removal of permanent magnetism, such as that from a horseshoe magnet, a watch, or a bar-magnet. Heat is the common depolarizer, but counter electro-magnetic forces are employed also in the various forms of apparatus known as demagnetizers.

=Deposit, Electrolytic.= The metal or other substances precipitated by the action of a battery or other current-generator, as in the plating processes.

=Detector.= A portable galvanometer, by means of which a current and its approximate strength can be detected and measured.

=Diaphragm.= In telephones and microphones, a disk of iron thrown into motion by sound-waves or by electric impulse. It is usually a thin plate of japanned iron, such as is used in the ferrotype photographic process for making tin-types.

=Dielectric.= Any substance through which electrostatic induction is allowed to occur, such as glass or rubber. It is a non-conductor for all electric currents.

=Dielectric Resistance.= The resistance a body offers to perforation or destruction by an electric discharge.

=Dimmer.= An adjustable choke or resistance coil used for regulating the intensity of electric incandescent lamps. It is employed extensively in theatres for raising or lowering the brilliancy of lights.

=Dipping.= The process of cleaning articles by dipping them in acids or caustic soda, preparatory to electro-plating.

Simple immersion, with or without current, to put a blush of metal on a cleaned surface.

=Dipping-needle.= A magnetic needle mounted on a horizontal bearing so that it will dip vertically when excited by a current passing horizontally about it. The ordinary compass-needle is mounted on a point, and swings freely to the right or left only.

=Direct Current.= (_See_ Current, Direct.)

=Discharge.= The eruptive discharge from a Leyden-jar or accumulator of a volume of electricity stored within it.

The abstraction of a charge from a conductor by connecting it to the earth or to another conductor.

=Discharge, Disruptive.= The discharge of a static charge through a dielectric. It involves the mechanical perforation of the dielectric.

=Disconnect.= To break an electric circuit or open it so as to stop the flow of current; to remove a part of a circuit or a piece of apparatus from a circuit.

=Distillation, Electric.= The distilling of a liquid by the employment of electricity, which, by electrifying the liquid, assists the effects of heat. It is asserted that the process is accelerated by the electrification of the liquid or fluid, but it must be a conductor liquid or electrolyte. Oil, being a non-conductor, is not affected by any electric current, no matter what its specific gravity may be.

=Distributing Centre.= The centre of distribution in a system having branch circuits, such as the electric-light or telephone outlets from a main station.

=Door-opener, Electric.= A magnetic contrivance arranged in connection with a lock, by means of which the latch is released by pressing a distant push-button. This device is used in flats and apartment-houses for opening a door from any of the apartments in the house.

=Double Filament Lamp.= An incandescent lamp having two filaments, one with a high capacity, the other with a low one. The high capacity may be from sixteen to fifty candle-power, the other from one to five. A turn of the bulb in its socket, or the pulling of a string which operates a switch in the socket, cuts out the current from the long filament and sends it through the shorter and finer one, thus giving a weaker light. These “hy-lo” lamps are useful as night lamps in halls, bath-rooms, or in sick-rooms, where a low or weak light is required all night.

=Double Pole-switch=. A cut-out that is arranged to cut out the circuit of both the negative and positive leads at the same time.

=Double-push.= A contact-push having two contacts and arranged so that pressure upon it opens one contact and closes the other.

=Double Throw-switch.= A switch so arranged that it can be thrown into either one of two contacts; a throw-over switch.

=Driving-pulley.= The broad-faced or channelled pulley on an armature shaft by means of which the power from a motor may be transmitted mechanically.

=Dry Battery.= (_See_ Battery, Dry.)

=Duct.= The space in an underground conduit for a single wire or cable.

=Duplex Wire.= An insulated conductor having two distinct wires twisted or laid together, but properly insulated from each other.

=Dynamic Electricity.= Electricity in motion or flowing, as distinguished from static or frictional electricity.

Electricity of relatively low potential or electro-motive force in large quantity or amperage.

=Dynamo.= An apparatus consisting of a core and field-magnets, properly wound with insulated wire, which, when put into operation by revolving the core or armature at high speed, develops electric current; a mechanical generator of electricity.

=Dynamo, Motor.= (_See_ Motor-dynamo.)

E

=Earth.= The accidental grounding of a circuit is termed an “earth.”

=Earth-plate.= A plate buried in the ground to receive the ends of telegraph lines and other circuits, and so give a ground connection. Copper plates are often used, but in houses the ground is usually formed by attaching a wire to the gas or water pipes.

=Earth Return.= The grounding of a wire in a circuit at both ends gives the circuit an earth return. This method is commonly used in telegraph lines, both in the wire and wireless systems.

=Eddy Currents.= (_See_ Currents, Eddy.)

=Edison Distributing-box.= A box used in the Edison “three-wire” system, from which the outlets pass to local circuits.

=Edison Lalande Cell.= A zinc-copper battery having a depolarizing coating of copper oxide on the copper element, the couple being immersed in an electrolyte composed of potash or caustic soda.

=Ediswan.= A term applied to the incandescent lamps invented by Edison and Swan and used extensively in Great Britain. Also applied to other apparatus designed by the two inventors.

=Efficiency.= The relation of work done to the electrical energy absorbed. The efficiency is not equal to the energy absorbed, because it always takes more power to generate a current than is given back in actual efficiency. This is due to mechanical friction and to the resistance of the air in a mechanism such as a dynamo when revolving at high speed.

=Efficiency, Electrical.= In a generator it is the total electrical energy produced, both that wasted and that actually used in driving machinery or apparatus.

=Efflorescence.= The dry salts on a jar or vessel containing liquid that collects above the water or evaporation line. This is due to creeping.

=Elasticity.= A property in some bodies and forces through which they recover their former figure, shape, or dimensions when the external pressure or stress is removed. Water has no elasticity. Air is very elastic; steam has a great volume of elasticity; while electricity is undoubtedly the most elastic of all in its motion through air, water, and other conducting mediums.

=Electric.= Pertaining to electricity; anything connected with the use of electricity. It has been a much-abused word, and its meaning has been garbled by the impostor, the crook, and the “business thief” in foisting on the public wares in which there was no electrical property whatever. “Electric” toothbrushes, combs, corsets, belts, and the like may contain a few bits of magnetized steel, but they possess no active therapeutic value.

=Electrical Engineer.= The profession of electrical engineer calls for the highest knowledge of electricity, both theoretical and practical. It embraces the designing and installation of all kinds of electrical apparatus.

=Electrician.= One versed in the practices and science of electricity; a practical lineman or wireman.

=Electricity.= One of the hidden and mysterious powers of nature, which man has brought under control to serve his ends, and which manifests itself mainly through attraction and repulsion; the most powerful and yet the most docile force known to man, coming from nowhere and without form, weight, or color, invisible and inaudible; an energy which fills the universe and which is the active principle in heat, light, magnetism, chemical affinity, and mechanical motion.

=Electricity, Atmospheric.= The electric currents of the atmosphere, variable but never absent. They include lightning, frictional electricity, the Aurora Borealis, the electric waves used in wireless telegraphy, etc. Benjamin Franklin indicated the method of drawing electricity from the clouds. In June, 1752, he flew a kite, and by its moistened cord drew an electric current from the clouds so that sparks were visible on a brass key at the ground end of the cord. Later, when a fine wire was substituted for the cord, and a kite was flown in a thunder-storm, the electric spark was vivid. This experiment confirmed his hypothesis that lightning was identical with the disruptive discharges of electricity.

=Electricity, Latent.= The bound charge of static electricity.

=Electricity, Negative.= (_See_ Negative Electricity.)

=Electricity, Positive.= (_See_ Positive Electricity.)

=Electricity, Voltaic.= Electricity of low potential difference and large current intensity.

Electricity produced by a voltaic battery or dynamo as opposed to static electricity, which is frictional and practically uncontrollable for commercial purposes.

=Electrification.= The process of imparting an electric charge to a surface. The term is applied chiefly to electro-static phenomena.

=Electrization.= In electro-therapeutics, the subjection of the human system to electric treatment. An electric tonic imparted by electro-medical baths through the nervous system.

=Electro-chemistry.= That branch of science which treats of the relations between electric and chemical forces in their different reactions and compounds. It deals with electro-plating, electro-fusing, electrolysis, etc.

=Electro-culture.= The application of electricity to the cultivation of plants. The use of electricity has been found very beneficial in some forms of plant growth.

=Electrocution.= Capital punishment inflicted by electric current from a dynamo of high electro-motive force. The current used is from 1500 to 2000 volts, and it acts to break down the tissues of the body.

=Electrode.= The terminals of an open electric circuit.

The terminals between which an electric arc is formed, as in the arc-light.

The terminals of the conductors of an electric circuit immersed in an electrolytic solution, such as the carbon and zinc of a battery.

=Electrolier.= A fixture for supporting electric lamps, similar to a chandelier for gas or candles. Combination electroliers conduct both gas and electricity.

=Electrolysis.= The separation of a chemical compound into its constituted parts by the action of an electric current.

=Electrolyte.= A body susceptible of decomposition by the electric current. It must be a fluid body and a conductor capable of diffusion as well as composite in its make-up. An elemental body such as pure water cannot be an electrolyte.

=Electrolytic Decomposition.= (_See_ Decomposition, Electrolytic.)

=Electrolytic Deposit.= (_See_ Deposit, Electrolytic.)

=Electrolytic Resistance.= (_See_ Resistance, Electrolytic.)

=Electro-magnetic Induction.= (_See_ Induction, Electro-Magnetic.)

=Electro-magnetism.= Magnetism created by electric current.

That branch of electrical science which treats of the magnetic relations of a field of force produced by a current.

=Electro-medical Bath.= A bath provided with connections and electrodes for causing a current of electricity to pass through the body of the patient.

=Electrometer.= An instrument used for measuring static electricity. Electrometers are different from galvanometers, since the latter depend on a current flowing through wires to create an action of the magnetic needles.

=Electro-motive Force.= Voltage. It may be compared to the pressure of water in hydraulic systems. The unit of electro-motive force is the volt.

=Electro-motor.= A term sometimes applied to a current-generator, such as a small dynamo or voltaic battery.

=Electro-plating.= (_See_ Plating, Electro.)

=Electropoion Fluid.= An acid depolarizing solution for use in zinc-carbon couples, such as the “Grenet” and “Daniell” cells. The bi-chromate-of-potash and sulphuric-acid solution for battery charges is a good example.

=Electroscope.= An apparatus for indicating the presence of an electric charge and whether the charge is negative or positive.

=Electrostatic Accumulator.= Two conducting surfaces, separated by a dielectric and arranged for the opposite charging of the two surfaces. A faradic or static machine for accumulating frictional electricity is an example.

=Electrostatics.= That division of electric science which treats of the phenomena of the electric charge, or of electricity in repose, as contrasted with electro-dynamics or electricity in motion.

=Electrotype.= The reproduction of a form of type or engraving by the copper electro-plating process. The original is coated with plumbago and a wax impression taken of it. The face of the negative is made conductive with plumbago or tin dust, then suspended in a copper bath and connected with the current. A film of copper will be deposited on the face of the wax impression.

=Element, Chemical.= Original forms of matter that cannot be separated into simple constituents by any known process. There are about seventy in all, but as science advances the list is constantly being revised. New elements are discovered and known ones are being resolved into simpler forms.

=Elements of Battery Cell.= (_See_ Battery Cell, Elements of.)

=Emergency Switch.= An auxiliary switch used as a controller on a car to reverse the action of the motor.

=E-M-F.= An abbreviation for electro-motive force, or voltage.

=Equalizer.= A term applied to a wire or bar in electro-magnetic mechanism for equalizing the pressure over a system.

=Exciter.= A generator used for exciting the field-magnets of a dynamo.

=Extension Call-bell.= A bell connected with a telephone call-bell, and located in another part of a building so as to give a distant summons.

=External Circuit.= (_See_ Circuit, External.)

F

=F.= The sign commonly employed to designate Fahrenheit. Thus, 30° F. means 30 degrees Fahrenheit, or 30 degrees above zero.

=False Magnetic Poles.= (_See_ Magnetic Poles, False.)

=Faradic.= Induced current produced from induction-coils and faradic machines.

A series of alternating electrostatic discharges, as from a Holtz influence machine.

=Faradic Coil.= (_See_ Coil, Faradic.)

=Faradic Currents.= (_See_ Currents, Faradic.)

=Faradic Machine.= An apparatus designed to produce faradic current.

=Feed.= To furnish an electric current, also spoken of in connection with the mechanism that moves the carbons in arc-lamps.

=Feeders, or Feed Wires.= The conductors which convey electric currents at different points, as in the trolley system. The current is carried along in large cables strung on poles or laid underground, and at proper distances lines are run in to feed the trolley wire.

=Field.= The space in the neighborhood of a dynamo or motor, or other generator of electric current, from which the apparatus takes its electricity, both electrostatic and magnetic.

=Field-magnet.= (_See_ Magnet, Field.)

=Field of Force.= The space in the neighborhood of an attracting or repelling mass or system. There are two kinds of fields of force--the electro-magnetic and the static--from which the respective pieces of apparatus draw their store of electricity.

=Filament.= A long, thin piece of solid substance. It is generally as thin as a thread and flexible enough to be bent.

The hairlike element in an incandescent lamp which, when heated by a current, glows and radiates light.

=Filaments, Paper.= Filaments for incandescent lamps made of carbonized paper. They were the ones originally used in electric lamps, but have been superseded by other substances easier to handle and more durable.

=Flow.= The volume of a current or stream escaping through a conductor, such as a wire, rod or pipe.

=Fluorescence.= The property of converting ether waves of one length into waves of another length. The phenomenon is utilized in the production of Geissler tubes and X-rays.

=Fluoroscope.= An apparatus for making examinations by means of the X-rays.

=Fluoroscopic Screen.= A screen overspread with fluorescent material and employed for fluoroscopic examinations in connection with the X-rays.

=Force.= Any change in the condition of matter with respect to motion or rest. Force is measured by the acceleration or change of motion that it can impart to a body of a unit mass in a unit of time. For instance, ten pounds pressure of steam will be indicated on a gauge made for measuring steam. That pressure of steam, with the proper volume behind it, is capable of instantly producing a given part of a horse-power. In the same way ten volts of electro-motive force is capable of pushing a current so as to exert a certain fraction of horse-power.

=Force, Electro-magnetic.= The force of attraction or repulsion exerted by the electro-magnet. It is also known as electric force in the electro-magnetic system.

=Foucault Currents.= (_See_ Currents, Foucault.)

=Fractional Distillation.= The process of evaporating liquids by heat, the most volatile being the first treated. When that has been evaporated and distilled the heat is raised and the next most volatile liquid is evaporated, and so on until all are evaporated, leaving as a residue the solids that were a part of the original mass of liquid.

=Friction.= The effect of rubbing, or the resistance which a moving body encounters when in contact with another body.

=Frictional Electric Machine.= An apparatus for the development or generation of high-tension frictional electricity.

=Frictional Electricity.= Electricity produced by the friction of dissimilar substances.

=Full Load.= A complete load. The greatest load a machine or secondary battery will carry permanently. The full capacity of a motor running at its registered speed for its horse-power.

=Furnace, Electric.= A furnace in which the heat is produced by the electric arc. It is the hottest furnace known to man, and temperatures as high as 7500° Fahrenheit have been developed in it.

=Fuse, Electric.= A fuse for igniting an explosive charge by electricity. It is made by bringing the terminals or ends of wires close together, so that they will spark when a current passes through them. Or a thin piece of highly resistant wire may be imbedded in an explosive and brought to white heat by current.

=Fuse-block.= An insulator having a safety-fuse made fast to it.

=Fuse-box.= A box containing a safety-fuse, generally of porcelain, enamelled iron, or some other non-conductor.

=Fuse-links.= Links composed of strips or plates of fusible metal serving the purpose of safety-fuses.

=Fusing-current.= A current of sufficient strength to cause the blowing or fusing of a metal.

G

=Galvanic.= Voltaic. Relating to current electricity or the electro-chemical relations of metals.

=Galvanic Taste.= A salty taste in the mouth resulting from the passage of a light current from a voltaic battery, the ends of the wires being held to either side of the tongue. This has been called tasting electricity, but it is really the decomposition of saliva on the surface of the tongue, due to electrolysis or the passage of a current through a liquid.

=Galvanism.= The science of voltaic, or current, electricity.

=Galvanizing.= Coating iron with a thin layer of zinc by immersing the object in the molten metal.

=Galvano-faradic.= In medical electricity the shocking-coil. The application of the voltaic current, induced by a secondary current (induction-coil), to any part of the body.

=Galvanometer.= An instrument for measuring current strength.

A magnetic needle influenced by the passage of a current through a wire or coil located near it.

=Galvanometer, Tangent.= A galvanometer provided with two magnetic needles differing in length, the shorter one serving to measure tangents, the longer being used for sine measurements of current strength.

=Galvanoscope.= An instrument, generally of the galvanometer type, used to ascertain whether a current is flowing or not.

=Generator.= An apparatus for maintaining an electric current, such as a dynamo, a faradic machine, a battery, etc.

=German-silver.= An alloy of copper, nickel, and zinc. Used chiefly in resistance-coils, either in the form of wire or in strips of the sheet-metal.

=Gold-bath.= A solution of gold used for depositing that metal in the electro-plating bath.

=Graphite.= A form of carbon. It occurs in nature as a mineral, and also is made artificially by the agency of electric heat.

=Gravity Battery.= (_See_ Battery, Gravity.)

=Grounded Circuit.= (_See_ Circuit, Grounded.)

=Ground-plate.= (_See_ Plate, Ground.)

=Ground-wire.= The contact of a conductor, in an electric circuit, with the earth. It permits the escape of current if another ground-wire exists.

=Guard Tube.= A tube inserted in a wooden or brick partition to insulate wires that may pass through it. These tubes are made of porcelain, gutta-percha, compositions of a non-conducting nature, and fibre.

=Gutta-percha.= Caoutchouc treated with sulphur to harden it; sometimes called vulcanized rubber or vulcanite. It is a product obtained from tropical trees, and when properly treated it is a valuable insulator in electrical work, particularly in submarine cables, since it offers great resistance to the destructive agencies of the ocean’s depths.

H

=Hand Generator.= A magneto-generator driven by hand for the generation of light currents.

=Harmonic Currents.= (_See_ Currents, Harmonic.)

=Harmonic Receiver.= A receiver containing a vibrating reed acted on by an electro-magnet. Such a reed answers only to impulses tuned to its pitch.

=Heat.= One of the force agents of nature. It is recognized in its effects through expansion, fusion, evaporation, and generation of energy.

=Heat, Electric.= Caused by a resisting medium, such as carbon or German-silver, when too much current is forced through it. The principle of the car-warmers, electric iron, electric chafing-dish, etc.

=Helix.= A coil of wire. Properly a coil of wire so wound as to follow the outlines of a screw without overlaying itself.

=Horse-power, Electric.= Meaning the same as in mechanics. Referred to when speaking of the working capacity of a motor or the power required to drive a dynamo.

=Horse-power Hour.= A unit or standard of electrical work theoretically equal to that accomplished by one horse during one hour.

=Horseshoe Magnet.= (_See_ Magnet, Horseshoe.)

=H-P.= Abbreviation for horse-power.

=Hydrometer.= An instrument employed to determine the amount of moisture in the atmosphere.

An instrument for determining through flotation the density or specific gravity of liquids and fluids. It consists of a weighted glass bulb or hollow metallic cylinder with a long stem on which the Baumé scale is marked. Dropping it into a liquid it floats in a vertical position, and sinks to a level consistent with the gravity of the fluid.

=Hydrometer, Baumé.= An apparatus for testing the gravity of fluids. The zero point corresponds to the specific gravity of water for liquids heavier than water. A gauge, valuable in testing acids and other fluids used in electrical work.

I

=Igniter.= A mechanical hand apparatus, in which a battery, induction-coil, and vibrator are located, and whose spark, jumping across a gap at the end of a rod, ignites or lights a gas flame, blasting-powder, or dynamite.

=I-H-P.= An abbreviation for indicated horse-power.

=Illuminating Power.= Any source of light as compared with a standard light--as, for instance, the illuminating power of an electric light reckoned in candle-power.

=Illumination.= A light given from any source and projected on a surface, per unit of area, directly or by reflection. It is stated in terms--as, for instance, the candle-power of a lamp. When speaking of an incandescent lamp we say it illuminates equal to four candle-power or it gives a light equal to sixteen candle-power.

=Immersion, Simple.= Plating, without the aid of a battery, by simply immersing the metal in a solution of metallic salt.

=Impulse.= The motion produced by the sudden or momentary action of a force upon a body. An electro-magnetic impulse is the action produced by the electro-magnetic waves in magnetizing a mass of soft iron and attracting to it another mass of iron or steel.

An electro-motive impulse is one where the force rises so high as to produce an impulsive discharge such as that from a Leyden-jar.

=Incandescence, Electric.= The heating of a conductor to red or white heat by the passage of an electric current. For example, an incandescent lamp.

=Incandescent Circuit.= (_See_ Circuit, Incandescent.)

=Incandescent Lamp-filament.= (_See_ Filament.)

=India-rubber.= (_See_ Caoutchouc and Gutta-percha.)

=Indicator-card.= The card used in galvanoscopes, volt and ampere meters, and other instruments. It is provided with a moving needle and is marked with a graduated scale.

=Induced.= Caused by induction, and not directly.

=Induced Current.= (_See_ Current, Induced.)

=Inductance.= That capacity of a circuit which enables it to exercise induction and create lines of force.

Inductance is the ratio between the total induction through a circuit to the current producing it.

=Induction, Back.= A demagnetizing force produced in a dynamo armature when a lead is given to the brushes. When the brushes are so set the windings on the armature are virtually divided into two sets: one a direct magnetizing set, the other a cross-magnetizing set which exerts a demagnetizing action on the other set. The position of the brushes on a dynamo or motor is indicated by their location, and if changed back induction will be the result.

=Induction-coil.= (_See_ Coil, Induction.)

=Induction, Electro-magnetic.= When negative and positive currents are brought towards each other against their material repulsive tendencies the result is work, or energy, and the consequent energy increases the intensity of both currents temporarily. The variations thus temporarily produced in the currents are examples of electro-magnetic induction. A current is surrounded by lines of force. The approach of two circuits--one negative, the other positive--involves a change in the lines of force about the secondary circuit. Lines of force and current are so intimately connected that a change in one compels a change in the other. Therefore, the induced current in the secondary may be attributed to the change in the field of force in which it lies. The inner and outer coils of wire about the soft iron wire composing an induction-coil are the best and simplest examples of electro-magnetic induction.

=Induction, Magnetic.= The magnetization of iron or other paramagnetic substances by a magnetic field. The magnetic influence of a bar excited under these conditions is shown by throwing iron filings upon it. They will adhere to both ends (that is at the negative and positive poles) but not at the middle.

=Inductor.= A mass of iron in a current generator which is moved past a magnet-pole to increase the number of lines of force issuing therefrom. It is generally laminated, and is used in inductor dynamos and motors of the alternating-current type.

=Influence, Electric.= Electric induction or influence which may be electro-static, current, or electro-magnetic.

=Influence Machine.= A static electric machine worked by induction, and used to build up charges of opposite nature on two separate prime-conductors.

=Installation.= The entire apparatus, building, and appurtenances of a technical or manufacturing plant or power-house. An electric-light installation would mean the machinery, street-lines, lamps, etc.

=Insulating Joint.= Used for the purpose of insulating a gas-pipe from an electric circuit.

=Insulating Varnish.= A varnish composed of insulating material, such as gums, shellac, or diluted rubber. Shellac dissolved in alcohol is perhaps the best. It is easy to make and dries quickly, making an insulating surface practical for almost every ordinary use.

=Insulation.= The dielectric or non-conducting materials which are used to prevent the leakage of electricity. The covering for magnet wires, and overhead conduits for power lines and electric lighting.

=Insulation, Oil.= Any non-combustible oil may be employed as an insulator to prevent electrical leakage in induction-coils, transformers, and the like. Its principal advantage lies in its being in liquid form, permitting of easy handling. Moreover, if pierced by a spark from a coil, it at once closes again without becoming ignited. A solid insulator, if pierced, is permanently injured.

=Insulator.= Any insulating substance or material to prevent the escape of current. The knobs of porcelain or glass to which wires are made fast.

=Insulator, Porcelain.= An insulator made of porcelain and used to support a wire.

=Intensity.= The intensity or strength of a current is its amperage. The strength of a magnetic field, its power to attract or magnetize.

=Internal Circuit.= (_See_ Circuit, Internal.)

=Internal Resistance.= (_See_ Resistance, Internal.)

=Interrupter.= A circuit-breaker. Any device which breaks or interrupts a circuit. It may be operated by hand or automatically.

The vibrator of an induction-coil.

The commutators of an armature.

=Isolated Plant.= The system of supplying electric energy by independent generating dynamos for each house, factory, or traction line.

=Isolation, Electric.= A term applied to “electric sunstroke.” Exposure to powerful arc-light produces effects resembling those of sunstroke.

J

=Joint.= The point where two or more electric conductors join.

=Joint Resistance.= The united resistance offered by a number of resistances connected in parallel.

=Jumper.= A short circuit-shunt employed temporarily around an apparatus, lamp, or motor to cut out the current.

=Jump-spark.= A disruptive spark excited between two conducting surfaces in distinction from a spark excited by a rubbing contact.

K

=Kaolin.= A form of earth or product of decomposed feldspar composed of silica and alumina. It is serviceable in insulating compounds.

=Kathode.= The terminal of an electric circuit whence an electrolyzing current passes from a solution. It is the terminal connected to the zinc pole of a battery or the article on which the electro-deposit is made.

=Key.= The arm of a telegraphic sounder by which the circuit is made and broken. A pivoted lever with a finger-piece which, when depressed, makes contact between a point and a stationary contact on the base.

=Keyboard.= A board, or table, on which keys or switches are mounted.

A switchboard.

=Kilowatt.= A compound unit; one thousand watts; an electric-current measure. Abbreviation, K-W.

=Kilowatt Hour.= The result in work equal to the expenditure or exertion of one kilowatt in one hour.

=Kinetoscope.= A photographic instrument invented by Edison for obtaining the effect of a panorama or moving objects by the display of pictures in rapid succession--in familiar parlance, “moving pictures.”

=Knife Switch.= A switch with a narrow and deep, movable blade, or bar of copper or brass, which resembles the blade of a knife. It is forced between two spring-clamps attached to one terminal so as to make perfect contact.

L

=Laminated.= Made up of thin plates, as an armature-core.

=Laminated Core.= (_See_ Core, Laminated.)

=Lamp-Arc.= A lamp in which the light is produced by a voltaic arc. Carbon electrodes are used, and a special mechanism operates and regulates the space between the carbons so that a perfect arc may be maintained.

=Lamp, Incandescent.= A lamp in which the light is produced through heating a filament to whiteness by the electric current. It consists of a glass bulb from which the air is exhausted and sealed, after the filament is enclosed. The ends of the filament are attached to platinum wires, which in turn are made fast to the contact-plates at the head of the lamp, so as to connect with the current.

=Lamp-socket.= A receptacle for an incandescent lamp. It is generally made of brass and provided with a key-switch to turn the current on and off.

=Latent Electricity.= (_See_ Electricity, Latent.)

=Lead.= (Not the metal.) An insulated conductor which leads to and from a source of power; an insulated conductor to and from a telegraph or telephone instrument; a circuit, a battery, or a station. Not a part of the line circuit.

That part of an electric light or power circuit which leads from the main to the lamps or motors.

=Leading-in Wires.= The wires which lead into a building from an aerial circuit.

The wires which lead in and out from a lamp, battery, or instrument.

=Leak.= An escape of electrical energy through leakage. This is more liable to occur in bare than in insulated wires. The escape of current from bare trolley wires is much greater than that from the insulated conductors, particularly in damp or rainy weather.

=Leclanché Battery.= (_See_ Battery, Leclanché.)

=Leyden-jar.= A type of static condenser. Its usual form is a glass jar. Tin-foil is pasted about its inner and outer surfaces covering about half the wall. The balance of the glass is painted with shellac or insulating varnish. The mouth is closed with a cork stopper, and through its centre a brass rod is passed which, by a short chain, is connected with the interior coating of the jar. The top of the rod is provided with a brass knob or ball, and from this last the spark is drawn.

=Lightning.= The electro-static discharge of clouds floating in the atmosphere. It is the highest form of frictional electricity, uncontrollable and very dangerous, since the strength of a single flash may run into hundreds of thousands of volts.

=Lightning-arrester.= An apparatus for use with electric lines to carry off to earth any lightning discharges that such lines may pick up; or it may be a form of fuse which burns out before the current can do any harm to the electrical mechanism.

=Line-insulator.= An insulator serving to support an aerial line.

=Lineman.= A workman whose business is the practical part of electrical construction in lines and conducting circuits.

=Link-fuse.= A plate of fusible metal in the shape of a link. It is used as a safety-fuse in connection with copper terminals.

=Liquefaction, Electric.= The conversion of a solid into a liquid by the sole agency of electricity in its heat action upon the solid.

=Liquid Resistance.= (_See_ Resistance, Liquid.)

=Lithanode.= A block of compressed lead binoxide, with platinum connections, for use in a storage battery.

=Litharge.= Yellow-lead. A chemical form of metallic lead.

=Load.= In a dynamo, the amperes of current delivered by it under given conditions of speed, etc.

=Local Action.= In a battery, the loss of current due to impurities in the zinc. The currents may circulate in exceedingly minute circles, but they waste zinc and chemicals and contribute nothing to the efficiency of the battery.

In a dynamo, the loss of energy through the formation of eddy currents in its core or armature, in the pole pieces, or in other conducting bodies.

=Lodestone.= The scientific name is magnetite. Some samples possess polarity and attract iron; these are called lodestones.

=Loop.= A portion of a circuit introduced in series into another circuit.

=Low Frequency.= A frequency (in current vibrations) of comparatively few alternations per second.

=Low Potential Current.= (_See_ Current, Low Potential.)

=Luminescence.= The power or properties some bodies have of giving out light when their molecular mass is excited. For example, phosphorus and radium.

=Luminous Heat.= The radiation of heat by electric current, which at the same time produces light. For example, the filament in an incandescent lamp.

=Luminous Jar.= A Leyden-jar whose coatings are of lozenge-shaped pieces of tin-foil between which are very short spaces. When discharged, sparks appear all over the surface where the small plates of metal nearly join.

M

=Magnet.= A substance or metal having the power to attract iron and steel.

=Magnet-bar.= A magnet in the shape of a straight bar. (_See_ Bar-magnet.)

=Magnet-coil.= A coil of insulated wire enclosing a core of soft iron through which a current of electricity is passed to magnetize the iron.

=Magnet-core.= An iron bar or mass of iron around which insulated wire is wound in order to create an electro-magnet.

=Magnet, Electric.= A magnet consisting of a bar of iron, a bundle of iron wires, or an iron tube, around which a coil of insulated wire is wound. When a current is passing through the coil its influence magnetizes the iron core, but directly the current ceases the magnetism disappears.

=Magnet, Field.= The electro or permanent magnet in a dynamo or motor, used to produce the area of electric energy.

=Magnet, Horseshoe.= A magnet of U shape with the poles or ends brought closer together than the other parts of the limbs. A soft iron bar is placed across the poles when not in use, as this serves to conserve the magnetism.

=Magnet, Permanent.= A term applied to a hard steel magnet possessing high retentivity, or the power to hold its magnetism indefinitely.

=Magnet, Regulator.= An electro-magnet whose armature moves in such a manner as to automatically shift the commutator-brushes, on a motor or dynamo, to a position which insures the preservation of both brushes and commutator-bars, and also produces a constant current.

=Magnet, Simple.= A magnet made of one piece of metal.

=Magnet Wire.= Insulated wire used for coils. Cotton or silk covered wire is the most serviceable for winding magnets.

=Magnetic Adherence.= The tendency of a mass of iron to adhere to the poles of a magnet.

=Magnetic Attraction and Repulsion.= The attraction of a magnet for iron, steel, nickel, and cobalt; also of unlike poles of magnets for each other. The like poles repel.

=Magnetic Circuit-breakers.= An automatic switch, or breaker, whose action is excited and controlled by an electro-magnet.

=Magnetic Concentration of Ores.= The separation of iron and steel from their gangue by magnetic attraction. It is applicable only when either the ore or the gangue is susceptible to the magnet.

=Magnetic Control.= The control of a magnetic needle, magnet, index, armature, or other iron indicator in a galvanometer, ammeter, or voltmeter by a magnetic field.

=Magnetic Dip.= The inclination from the horizontal position of a magnetic needle that is free to move in a vertical plane.

=Magnetic Field, Rotary.= A magnetic field resulting from a rotary current.

=Magnetic Field, Shifting.= A magnetic field which rotates. Its lines of magnetic force vary, therefore, in position.

=Magnetic Field, Uniform.= A field of uniform strength in all portions, such as the magnetic field of the earth.

=Magnetic Force.= The power of attraction and repulsion exercised by a magnet; the force of attraction and repulsion which a magnet exercises, and which, in its ultimate essence, is unknown to science.

=Magnetic Induction.= (_See_ Induction, Magnetic.)

=Magnetic Needle.= A magnet having a cup or small depression at its centre, and poised on a sharp pin of brass, so as to be free to rotate. Its N pole points to the north, and its S pole to the south. A compass needle.

=Magnetic Poles.= The terrestrial points towards which the north or south poles of the magnetic needle are attracted. There are two poles: the arctic, or negative, which attracts the positive or N pole of the magnetic needle; and the antarctic, or positive, which attracts the S pole of the needle.

=Magnetic Poles, False.= It has been established that there are other poles on the earth that attract the magnetic needle when the latter is brought into their vicinity. These are called false poles, and are probably caused by large deposits of iron lying close to the surface of the earth.

=Magnetic Separator.= An apparatus for separating magnetic substances from mixtures. It is used chiefly in separating iron ore from earth and rock. The mineral falls on an iron cylinder, or drum, magnetized by coils, and adheres there, while the earth or crushed rock drops below. The particles of iron are afterwards removed by a scraper. The machine is also used in separating iron filings and chips from brass, copper, or other metals, the iron adhering to the magnet, while the brass and other chips drop underneath.

=Magnetism.= The phenomena of attraction exerted by one body for another. It has been commonly understood that magnetism and electricity are very closely related, for without electricity magnetism could not exist, although it has not been shown clearly that magnetism plays any part in the generation of electricity. Magnetism is the phenomenal force exerted by one body having two poles (negative and positive) for like bodies. The horseshoe magnet or a bar of magnetized steel are the simplest examples of this. If both ends of the horseshoe were positive they would not attract, but would repel. If both ends of a bar were positive they would repel; but as one is negative, or north-seeking, and the other positive, they exert lines of force which attract like bodies, such as bits of iron, nails, and needles. No energy is required to maintain magnetism in a tempered steel object, such as the wiring about a soft iron core when it has been magnetized, but electric current must flow about the soft iron core in order to render it a magnet. So soon as the current ceases to flow the magnetism ceases and the soft iron fails to attract.

=Magnetism, Uniform.= Magnetism that is uniform throughout a mass of magnetic steel, or a core that is electro-magnetic.

=Magnetize.= To impart magnetic property to a substance capable of receiving it.

=Magnetizing-coil.= (_See_ Coil, Magnetizing.)

=Magneto Call-bell.= A call-bell used principally in telephone systems, and operated by a current from a magneto-electric generator. The current is excited by turning the handle at the side of the telephone-box before removing the receiver from the hook.

=Magneto-generator.= A current-generator composed of a permanent magnet and a revolving armature which is rotated between the poles of the permanent magnet.

=Main Circuit.= (_See_ Circuit, Main.)

=Main Feeder.= The main wire in a district to which all the feeder wires are attached.

=Main Switch.= The switch connected to the main wire of a line, or the main-switch controlling a number of auxiliary switches.

=Mains, Electric.= The large conductors in a system of electric light or power distribution.

=Make and Break, Automatic.= An apparatus which enables the armature of a magnet to make and break its circuit automatically.

=Make-and-break Current.= (_See_ Current, Make-and-break.)

=Mercurial Air-pump.= An air-pump operated by mercury to obtain a high vacuum, and used extensively for exhausting incandescent-lamp bulbs.

=Mercury Tube.= A glass tube sealed and containing mercury. It is so arranged as to give out fluorescent light when shaken or agitated by an electric current. For example, the Geissler tubes, the Cooper-Hewitt light, Crook’s tubes, etc.

=Metallic Arc.= An arc which forms between metallic electrodes.

=Metallic Circuit.= (_See_ Circuit, Metallic.)

=Metallic Conductor.= A conductor composed of a metal.

=Metallic Filament.= A metal wire used in an incandescent lamp--the filament.

=Metallic Resistance.= (_See_ Resistance, Metallic.)

=Metallurgy.= The art of working metals. Electro-metallurgy applies to the processes wherein electricity plays the most important part.

=Mica.= A natural mineral of sheet form and translucent, used extensively as an insulator in electrical equipment and mechanism.

=Mica, Moulded.= A composition composed of ground mica and shellac as a binder. When heated and pressed into various shapes and forms, it is a valuable insulator, and is employed for hooks, locks, tubes, sockets, and the like.

=Micanite.= An insulating material made by cementing laminations of pure mica together and cementing them with shellac or other suitable non-conducting adhesives.

=Molecular Adhesion.= The attraction of similar molecules for each other.

=Molecular Attraction.= The attraction of molecules, or physical affinity.

=Molecular Resistance.= The resistance which a mass or electrolyte offers when contained in an insulated vessel and a current of electricity is passed through it.

=Molecule.= One of the invisible particles supposed to constitute matter of every kind; the smallest particle of matter that can exist independently. It is made up of atoms, but an atom cannot exist alone.

=Morse Receiver.= The receiving instrument once universally used in the Morse system of telegraphy, but now superseded by the sounder.

=Morse Recorder.= An apparatus which automatically records on a ribbon of paper the dots and dashes of the Morse telegraph alphabet.

=Morse Sounder.= An electro-magnetic instrument designed to make a sharp, clicking sound when its armature lever is drawn down by the attraction of the magnets.

=Morse System.= A telegraphic system invented by Prof. S. F. B. Morse, in which, by means of alternating makes and breaks of varying duration, the dots and dashes of the Morse alphabet are reproduced and received at a distance through the agency of wires and the electro-magnetic sounder.

=Motor, Electric.= A machine or apparatus for converting electric energy into mechanical kinetic energy or power. The electrical energy is usually generated by a dynamo, and distributed on conductors to motors located at various points.

Electric motors are of two types--the A-C., or alternating current, and the D-C., or direct current.

=Motor-car, Electric.= A self-propelling car driven by stored electricity.

=Motor-dynamo.= A motor driven by a dynamo whose armature is firmly attached or connected to that of the dynamo. It is used for modifying a current. If the dynamo generates an alternating current of high potential, the motor converts it into a direct current of lower voltage but increased amperage.

=Motor-transformer.= A transformer which is operated by a motor.

A dynamo-electric machine provided with two armature windings, one serving to receive current, as a motor, the other to deliver current, as a generator, to a secondary circuit.

N

=N.= An abbreviation for the north-seeking pole in a magnet.

=Natural Magnet.= A loadstone.

=Needle.= A term applied to a bar-magnet poised horizontally upon a vertical point.

A magnetic needle, or the magnet in a mariner’s compass.

=Negative.= Opposed to positive.

=Negative Electricity.= The kind of electricity with which a piece of amber is charged by friction with flannel.

In a galvanic battery or cell the surface of the zinc is charged with negative electricity. Negative electricity, according to the theory of some scientists, really means a deficiency of electricity.

=Negative Electrode.= The same as Negative Element.

=Negative Element.= The plate not dissolved by the solution in a voltaic cell; the one which is positively charged.

The carbon, platinum, or copper plate or pole in a battery.

=Negative Feeder.= The conductor which connects the negative mains with the negative poles of a generator.

=Negative Plate.= (_See_ Plate, Negative.)

=Negative Pole.= (_See_ Pole, Negative.)

=Neutral Feeder.= The same as Neutral Wire.

=Neutral Wire.= The central wire in a three-wire system.

=Nickel-bath.= A bath for the electro-deposition of nickel.

=Non-arcing Fuse.= A fuse-wire which is enclosed in a tube packed with asbestos or silk, and which does not produce an arc when it fuses or blows out. It is practically noiseless, save for a slight hissing sound, accompanied by a light puff of smoke, which escapes from a venthole in the side of the tube.

=Non-conductor.= A material or substance offering very high resistance to the passage of the electric current.

=Non-magnetic Steel.= Alloys of iron incapable of being magnetized. They are composed of iron and manganese, nickel, steel, etc.

=Normal.= Regular. The average value of observed quantities. Normal current is a regular current without variations.

The force of a current at which a system is intended to work.

=Normal Voltage.= The same as Normal Current.

=North Pole.= The north-seeking pole of a magnet.

The pole of a magnet which tends to point to the north, and whence lines of force are assumed to issue on their course to the other pole of the magnet.

O

=O.= An abbreviation for Ohm.

=Oersted’s Discovery.= Oersted discovered, in 1820, that a magnetic needle tended to place itself at right angles to a current of electricity. This fundamental principle is the basis of the galvanometer, the dynamo, and the motor.

=Ohm.= The practical unit of resistance. A legal ohm is the resistance of a column of mercury one square millimetre in cross-sectional area and 106.24 centimetres in length.

=Ohm, True.= The true ohm is the resistance of a column of mercury 106.24 centimetres long and one square millimetre in cross-sectional area. An ohm may be measured by a No. 30 copper wire nine feet and nine inches long. If larger size wire is used the piece must be proportionately longer, since the resistance is less.

=Ohmic Resistance.= True resistance as distinguished from spurious resistance, or counter electro-motive force. (_See also_ Resistance, Ohmic.)

=Ohm’s Law.= The basic law which expresses the relations between current, electro-motive force, and resistance in active circuits. It is formulated as follows:

1. The current strength is equal to the electro-motive force divided by the resistance.