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.
2. The electro-motive force is equal to the current strength multiplied
by the resistance.
3. The resistance is equal to the electro-motive force divided by the
current strength.
=O. K.= A telegraphic signal meaning yes, or all right. It is supposed
to be a misspelled form of all correct, “Oll Kerrekt.”
=Okonite.= A form of insulation for wires and conductors; a trade name
applied to insulations, and protected by copyright.
=Open Arc.= A voltaic arc not enclosed.
=Open Circuit.= (_See_ Circuit, Open.)
=Oscillating Current.= (_See_ Current, Oscillating.)
=Outlet.= That part of an electrolier or electric light fixture out of
which the wires are led for attachment to incandescent light sockets.
=Outside Wiring.= The wiring for an electric circuit which is located
outside a building or other structure.
=Overhead Feeders.= The same as overhead conductors.
=Overhead Trolley.= The system in which the current for the propulsion
of trolley-cars is taken from overhead feeders or wires.
=Overhead Trolley-wire.= A naked, hard copper wire drawn at high
tension, and suspended over or at the side of a car-track, and from
which the trolley-wheel takes its current.
=Overload.= In an electric motor, an excess of mechanical load prevents
economical working, causing the armature to revolve slowly and the
wiring to heat. In this case heating implies waste of energy.
=Overload Switch.= A switch which operates automatically to open a
circuit in line with a motor, and so save the motor from overheating or
burning in the event of an overload.
P
=Paper Cable.= A cable insulated with waxed or paraffined paper.
=Paraffine.= A residuum of petroleum oil, valuable as an insulating
medium in electrical work.
A hydro-carbon composition of the highest resistance known. It is
extensively used in condensers and other electrical apparatus as a
dielectric and insulator.
=Parallel Distribution.= A distributing system for electricity wherein
the receptive contrivances are adjusted between every two of a number of
parallel conductors running to the limits of the system. When two or
more conductors connect two mains of comparatively large size and low
resistance, they are said to be in parallel or in multiple. This order
is easily pictured by imagining the mains to be the sides of a ladder
and the conductors the rungs. In the latter the lamps are placed. It
follows that the current flows from one main to the other through the
conductors and lamps.
=Paramagnetic.= Substances which have magnetic properties, or those
which are attracted by magnetic bodies. A paramagnetic substance has
high multiplying power for lines of force, therefore a bar of iron which
is a paramagnetic substance of the highest quality becomes magnetic when
placed within a circle of electric lines of force. The first example of
paramagnetic substance brought to the attention of man was the
lodestone, from which the ancient mariners fashioned their crude compass
needles.
=P-C.= An abbreviation for porous cup.
=Pear Push.= A push-button enclosed in a handle having the shape of a
pear. It is generally attached to the end of a flexible wire cord.
=Periodic Current.= (_See_ Current, Periodic.)
=Permanency, Electric.= The power of conductors to retain their
conductivity unaffected by the lapse of time.
=Permanent Magnet.= (_See_ Magnet, Permanent.)
=Phase.= One complete oscillation. The interval elapsing from the time a
particle moves through the middle point of its course to the instant
when the phase is to be stated.
Simple harmonic motion. Oscillation.
=’Phone.= An abbreviation for the word Telephone.
=Phonograph.= An apparatus for reproducing sound. It is vibratory and
not electric in its action, except that the mechanism may be driven by
electricity. It consists of a rotating cylinder of a waxlike material
and a glass diaphragm carrying a needle-point that lightly touches the
surface of the waxen cylinder. If the diaphragm is agitated the needle
vibrates, making indentations in the surface of the wax. If the needle
is set back and the cylinder rotated so as to carry the point over the
indentations, the sound is given back through the vibration of the
diaphragm.
=Pickle.= An acid solution used to cleanse metallic surfaces preparatory
to electro-plating.
=Pilot Wires.= Wires brought from distant parts of electric light and
power mains, and leading to voltmeters at a central station. Through
their agency the potential energy of every part of the system may be
measured.
=Pith-balls.= Balls made from the pith of light wood, such as elder.
They are used in the construction of electroscopes and for other
experiments in static electricity.
=Plant.= The apparatus for generating electric current, including
engines, boilers, dynamos, mains, and subsidiary apparatus.
=Plate, Condenser.= In a static apparatus, the condenser having a flat
piece of glass for a dielectric. It is mounted on an axle so that it may
be revolved.
=Plate, Ground.= In a lightning-arrester, the plate connected to the
earth or ground wire.
=Plate, Negative.= In a voltaic battery, the plate which is unattacked
by the fluid. It is made of carbon, platinum, or copper.
=Plate, Positive.= (_See_ Positive Plate.)
=Plating-bath.= A vessel of solution for the deposition of metal by
electrolysis. Used in electro-plating.
=Plating, Electro.= The process of depositing metal on surfaces of
metals or other substances by the aid of an electrolyte and the electric
current.
=Platinum Fuse.= A slender wire of platinum roused to incandescence by
current, and used to explode a charge of powder or other combustible
substance.
=Plug.= A piece of metal, with a handle, used to make electric
connections by being inserted between two slightly separated plates or
blocks of metal.
A wedge of metal, slightly tapered, and used to thrust between two
conductors to close or complete a circuit.
=Plumbago.= Soft, lustrous graphite; a native form of carbon sometimes
chemically purified. It is used chiefly in electrotyping for dusting the
wax moulds to make the surface an electric conductor.
=Plunge-battery.= (_See_ Battery, Plunge.)
=Polar.= Pertaining to one of the poles of a magnet.
=Polarity.= The disposition in a body to place its axis in a particular
direction when influenced by magnetism. For example, the attraction and
repulsion at the opposite ends of a magnet. The N and S seeking poles of
a compass needle is the simplest example.
=Polarity, Electric.= The disposition in a paramagnetic body to be
influenced by electric waves and lines of force. The otherwise
non-magnetic body or mass becomes magnetic to attract or repulse when
influenced by electricity, but ceases to retain the phenomena after the
electric influence is removed. A piece of soft iron wire, a nail, or a
short rod of iron will become electro-polarized when a current of
electricity is sent through a coil of insulated wire so wound that one
end will be N the other S. So soon as the circuit is broken the polarity
ceases.
=Polarization.= The depriving of a voltaic cell of its proper
electro-motive force. This may be brought about through the solution
becoming spent, or in the event of the acid being saturated with zinc,
and so failing to act on the metallic zinc.
Counter electro-motive force due to the accumulation of hydrogen on the
negative plate.
=Polarizing-current.= (_See_ Current, Polarizing.)
=Polar Surface.= The surface of a magnetic substance through which the
magnetic flux passes in or out.
=Pole-changer.= An automatic, oscillating switch or contact-breaker
which reverses the direction of the current.
=Pole, Negative.= The S pole in a magnet or compass needle.
=Pole, Positive.= (_See_ Positive Pole.)
=Pole-switch, Single.= A switch designed to open or close one lead
only.
=Poles.= The terminals of an open electric circuit at which there
necessarily exists a potential difference.
The terminals of an open magnetic circuit, or the ends of a magnetized
mass of iron.
=Porcelain.= A fine variety of earthenware, valuable for insulators and
insulating purposes.
=Porosity.= The state or property of having small interstices or holes.
The opposite of density.
=Porous Cup or Cell.= A cup or cell made of pipe-clay or of unglazed
earthenware through which a current of electricity can pass when wet or
in a liquid. Porous cups are used in cells and batteries to keep two
liquids apart, and yet permit electrolysis and electrolytic conduction.
=Positive Currents.= Currents which deflect the needle to the left.
=Positive Electricity.= The current that flows from the active element,
the zinc in a battery, to the carbon. The negative electricity flows
from the carbon to the zinc.
=Positive Electrode.= The electrode which is connected with the positive
pole of a source of electric energy.
=Positive Feeders.= The lead or wire in a set of feeders which is
connected to the positive terminal of the generator.
=Positive Plate.= In a voltaic cell, the plate which is acted upon and
corroded. The current from the positive plate is negative electricity.
=Positive Pole.= The N pole in a magnet or magnetic needle. So called
because it seeks the north or negative pole of the earth.
=Positive Wire, or Conductor.= The wire, or conductor, connected with
the positive pole of any apparatus which produces electro-motive force.
=Potential, Electric.= The power to perform electric work.
=Potential Energy.= Capacity for doing work. Potential energy when
liberated becomes actual energy for the performance of work.
=Power-generator.= Any source from which power is generated.
=Power-house.= A station in which the plant of an electric power system
is operated and the current distributed to local or long-distance
points. Power-houses are either primary or secondary stations. In the
primary station the current is generated directly by the aid of
mechanical power, either the steam-engine or the steam-turbine. The
secondary station, or sub-station, is located at a distance from the
main power-house, and has no mechanical means of generating current. The
current, usually of high alternating voltage, is supplied to the
sub-station from the main power-house; and by means of transformers and
converters, the high-voltage current is transformed into one of lower
E-M-F and higher amperage, for distribution over local lines.
=Power-unit.= The unit of electric power is the volt-ampere or watt.
=Pressure, Electric.= Electro-motive force or voltage.
=Primary.= A term used to designate the induction-coil in an
induction-apparatus or transformer. It is an abbreviation for primary
coil.
=Primary Battery.= (_See_ Battery, Primary.)
=Prime Conductor.= (_See_ Conductor, Prime.)
=Push-button.= A switch for closing a circuit by means of pressure
applied to a button. The button is provided with a spring, so that when
pushed in and released it flies back, reopening the circuit.
=Pyrogravure.= A process of engraving by the use of platinum points
heated to redness by the electric current.
Q
=Q.= Abbreviation or symbol for electric quantity.
=Quadrant.= The quarter of a circle or of its circumference.
=Quadruple Circuit.= (_See_ Circuit, Quadruple.)
=Quantity.= The term is applied to express arrangements of electrical
connections for giving the largest possible amount of current.
=Quantity, Electro-magnetic.= The electro-magnetic current measured by
its intensity for a second of time.
=Quick-break.= A break affected in an electric current by the employment
of a quick-break switch.
=Quickening.= The amalgamating of the surface of a metallic object
before electro-plating it with silver. This secures better adhesion of
the deposit, and is done by dipping the article into a solution of
mercurial salts--one part of mercuric nitrate to one hundred parts of
water.
R
=Radiant Energy.= Energy existing in the luminiferous ether and
exercised in wave transmission, creating light or sound. Radium
possesses the highest form of radiant energy.
=Radiate.= To emit or send out in direct lines from a point or points,
as radiating heat, light, or sound. The radiations are sent out in all
directions from a central point, just as a stone thrown in a pond of
still water will radiate waves or ripples from the central point.
=Radiation.= The travelling or motion of ether waves through space.
=Radiator, Electric.= A series of plates or wire-coils heated by
current. They radiate heat and so warm the surrounding air.
=Radiograph.= A photographic picture taken by the X-ray process.
=Receiver.= In telephony or telegraphy, an instrument for receiving the
message as distinguished from the instrument sending or transmitting the
message.
The telephone piece held to the ear is the receiver.
=Receiving End.= The end of a line where the operative currents are
received, as opposed to the end at which they are transmitted.
=Receptacle.= A device for the installation of an attachment or
extension plug. Used in connection with electric-lighting circuits.
=Recoil Kick.= Reaction resulting from a disruptive discharge.
=Recorder.= In telegraphy, the receiving apparatus for recording the
dot-and-dash signals on a strip or tape of paper.
=Reduction.= The influence exerted without apparent communication by a
magnetic field or a charged mass upon neighboring bodies. The
induction-coil is a simple example of this force. The current passes
through the primary or inner coil about a core of soft iron, and in
doing so it develops lines of force in the secondary or outer coils,
although no current is flowing directly through them from a battery or
dynamo.
=Reduction Gear.= A gear which acts to reduce a speed below that of a
motor in full motion without lessening its motive force.
=Refract.= To break the natural course of light in an elastic medium.
The rays of light, as they pass from a rare into a dense medium, are
refracted.
=Register, Electric.= An apparatus for registering and recording the
movements of employés about a building. Press-buttons are arranged
throughout the building, and when a man passes a station he presses the
button, and the time is recorded by the apparatus.
=Regulator Magnet.= (_See_ Magnet, Regulator.)
=Relay.= A telegraphic or telephonic receiving instrument which opens
and closes a local circuit through movements caused by the impulses of
currents received. The relay battery may be very delicate so as to work
with weak currents. The function of the relay is to open and close
circuits for the admission of a new current to push on the sound or
vibration to a more distant point. The main battery may be of any
desired power.
=Relay Connection.= A connection used in telegraphy, including a local
battery, with a short circuit, normally open, but closed at will by a
switch and sounder, or other appliance. A very weak current will work
the apparatus.
=Relay, Ordinary.= A relay that is not polarized.
=Relay, Repeating.= In telegraphy, a relay for repeating the signals
through a second line.
=Reluctance.= Magnetic resistance.
=Repeater.= In telegraphy, an instrument for repeating the signals
through a second line. It is virtually a relay which is controlled by
the sender, and which, in turn, operates the rest of the main line. It
is usually located at about the middle of the total distance covered.
=Repeating-station.= A telegraph station located on a long line, and
occupying a position at the juncture of the sections into which the line
is divided. The currents received through one section are repeated into
the other sections by means of a repeater.
=Repulsion, Electric.= The tendency which exists between two bodies
charged alike to mutually repel each other.
=Residual Charge.= (_See_ Charge, Residual.)
=Resilience.= The power to spring back to a former position. Electricity
is resilient, although its elasticity cannot be measured accurately.
=Resin.= A solid inflammable substance or gum, and a good non-conductor
in electrical work. It is the product obtained by distilling the sap of
the pitch-pine. The name is also applied to the product of distilling
the sap of other trees. Common resin, shellac, lac, Dragon’s-blood, and
other substances of a similar nature are resins. They are all
dielectrics, and the source of negative frictional electricity when
rubbed with cotton, wool, flannel, silk, or fur.
=Resistance.= That quality of an electric conductor in virtue of which
it opposes the passage of an electric current, causing the disappearance
or modification of electro-motive force, and converting electric energy
into heat energy.
=Resistance-box.= A box filled with resistance-coils connected in series
and provided with a switch, so that any number of the coils may be cut
out.
=Resistance, Carbon.= A resistance composed of carbon as a substitute
for a coil of wire. Carbon rods are placed close together having an air
space between them, with alternate ends connected. Piles may be built up
of carbon plates, whose resistance is made to vary by changing the
pressure.
=Resistance-coil.= A coil of wire metal or other substances having the
power to resist a current of electricity.
A coil of wire used to measure an unknown resistance by virtue of its
own known resistance. (_See also_ Coil, Resistance.)
=Resistance, Dielectric.= (_See_ Dielectric Resistance.)
=Resistance, Electrolytic.= The resistance of an electrolyte to the
passage of a current decomposing it. It is almost entirely due to
electrolysis, and is intensified by counter-electro-motive force. When a
current of a voltage so low as not to decompose an electrolyte is passed
through the latter, the resistance appears very high and sometimes
almost infinite. If the voltage is increased until the electrolyte is
decomposed the resistance suddenly drops to a point lower than the true
resistance.
=Resistance, Internal.= The resistance of a battery, or generator, in an
electric circuit as distinguished from the resistance of the rest of the
circuit.
=Resistance, Liquid.= A liquid of varying specific gravity used to
create resistance to the passage of the electric current.
Resistance effected by the use of liquid through which a current must
pass to complete a circuit.
=Resistance, Metallic.= The resistance of metals to the electric
current.
German-silver resistance as distinguished from that of water, carbon, or
other substances.
=Resistance, Ohmic.= True resistance measured in ohms as distinguished
from counter electro-motive force. (_See also_ Ohmic Resistance.)
=Resistance, Spurious.= The counter-electro-motive force. In its effect
of opposing a current and in resisting its formation it differs from
true resistance. True resistance diminishes current strength, absorbs
energy, and develops heat. Spurious resistance opposes and diminishes a
current without absorption of energy or production of heat.
=Resistance, Standard.= A known resistance employed to determine unknown
resistances by comparison.
=Resistance, True.= The true resistance measured in ohms as
distinguished from counter-electro-motive force.
=Resonator, Electric.= A small, open electric circuit with ends nearly
touching. When exposed to electric resonance, or to a sympathetic
electric oscillating discharge, a spark passes across the gap. The spark
is due to inductance in the resonator.
=Retentiveness.= That property which enables steel to retain its
magnetism.
=Return.= A line or conductor which carries current back to its
starting-point after it has traversed a circuit. The best definition of
a return is a circuit on which no new apparatus is installed.
=Return-circuit.= (_See_ Circuit, Return.)
=Return-circuit, Railway.= A grounded circuit used in trolley systems
for ground returns through the tracks, they being joined by links or
flexible wires so as to form perfect conductors. It is the negative side
of the system, the positive being in the overhead or underground
feed-wire or rail.
=Reversibility.= The principle by which any form of generator for
producing a given form of energy may be reversed to absorb energy. The
dynamo of the reversible type driven to generate current may be reversed
and will develop power if a current is run through it.
=Rheostat.= An adjustable resistance. An apparatus for changing the
resistance, without opening the circuit, by throwing a switch-bar across
contact points.
=Rod Clamp.= A clamp used in the lamp rod of an arc-light to hold the
carbon.
=Röntgen Effects.= Phenomena obtained by the use of the X or Röntgen
rays.
=Röntgen-ray Screen.= A screen whose surface is covered with
fluorescent material for the purpose of receiving and displaying the
Röntgen image.
=Röntgen Rays.= A peculiar form of light radiation discovered by
Röntgen, and which is emitted from that portion of a high vacuum tube
upon which the kathode rays fall.
=Rotary Magnetic Field.= (_See_ Magnetic Field, Rotary.)
=Ruhmkorff Coil.= (_See_ Coil, Ruhmkorff.)
S
=Safety Fuse.= A device to prevent overheating of any portion of a
circuit by excessive current. It generally consists of a strip of
fusible metal which, if the current attains too great strength, melts
and opens the circuit.
=Salt.= A chemical compound containing two atoms or radicals
which saturate each other. One is electro-positive, the other
electro-negative.
Salts are decomposed by electrolysis, and in separating they combine to
form new molecules.
=Saturated.= A liquid is said to be saturated when it has dissolved all
the salts it will take up.
=Search-light.= An apparatus for producing a powerful beam of light and
projecting it in any desired direction.
=Secondary.= A term applied to the secondary coil of a transformer or
induction-coil.
=Secondary Battery.= (_See_ Battery, Secondary.)
=Secondary Plates.= The plates of a secondary battery or
storage-battery. When charged, the negative plate should be brown or
deep reddish in color, and the positive slate-colored.
=Self-excited.= Electrified by its own current.
=Self-winding Clock.= A clock which automatically winds itself by
electricity. It is operated by a small electro-magnetic motor which
obtains its current from an outside source.
=Semaphore, Electric.= An apparatus for exhibiting signals. Used in the
railway block system.
=Series.= Arranged in succession. When incandescent lamps are installed
so that the current goes in and out of one lamp, and so on to the next
and the succeeding ones, they are said to be arranged in series. It
takes high E-M-F and current, or amperage, to operate such lamps.
Series batteries are arranged with the zinc pole of one connected to the
carbon pole of the next.
=Series Arc Cut-out.= A device by means of which a short circuit is
established past a defective lamp, thereby securing the undisturbed
operation of all the other lamps in the circuit.
=Series Distribution.= A distribution of electricity in which the
receptive devices are arranged in successive order upon one conductor,
extending the entire length of the circuit.
=Series Dynamo.= A series-wound dynamo.
=Series Incandescent Lamp.= An incandescent lamp adapted for service in
a series circuit.
=Series Motor.= A motor adapted for use in a series circuit; a motor
whose field-coil winding is in series with the armature.
=Series, Multiple.= An arrangement of electric apparatus in which the
parts are grouped in sets in parallel, and these sets are connected in
series.
=Series Winding.= A method of winding a generator or motor in which one
of the commutator brush connections is joined to the field-magnet
winding. The other end of the magnet winding is connected with the outer
circuit, and the second armature brush is coupled with the remaining
terminal of the outer circuit.
=Service Wires.= Wires connected to the supply circuit or main wires,
and which run into buildings to supply current for heat, light, and
power.
=Shellac.= A resin gum, gathered from certain Asiatic trees. It is
soluble in alcohol, and is used extensively in electric work as an
insulator.
=Shifting Magnetic Field.= (_See_ Magnetic Field, Shifting.)
=Shock, Electric.= The effect upon the animal system of the discharge of
an electric current of high potential difference. The voltage is the
main element in a shock.
=Shoe.= As applied to electric railways, the casting employed to bear on
the third rail to take in positive current and electro-motive force.
The cast-iron plate of an electric break, which, by magnetism, adheres
to another iron surface.
=Short Circuit.= (_See_ Circuit, Short.)
=Shunt-box.= A resistance-box designed for use as a galvanometer shunt.
The box contains a series of resistance-coils which can be plugged in or
out as required.
=Shunt-winding.= A dynamo or motor is shunt-wound when the field-magnet
winding is parallel with the winding of the armature.
=Silver-bath.= A solution of a salt of silver used in the
electro-plating process.
=Silver-plating.= Depositing a coating of silver on a metallic surface
by the acid of electro-metallurgy.
=Silver-stripping Bath.= An acid solution used for stripping silver
from a metallic surface before re-plating it.
=Simple Circuit.= (_See_ Circuit, Simple.)
=Simple Immersion.= (_See_ Immersion, Simple.)
=Simple Magnet.= (_See_ Magnet, Simple.)
=Single-trolley System.= A trolley system employing only one overhead
conducting wire, the track and ground serving as the return-circuit.
=Single-wound Wire.= Wire insulated by winding or overlaying with but a
single layer of material.
=Sliding-condenser.= (_See_ Condenser, Sliding.)
=Snap-switch.= A switch so contrived as to give a quick break. A spiral
spring is fastened between the handle and arm in such a manner that when
the handle is drawn back the spring operates and quickly draws a
knife-bar from the keeper, breaking the contact instantly and without
the formation of an arc.
=Socket.= A receptacle for an incandescent lamp or plug.
=Solenoid.= A helical coil of wire of uniform diameter or cylindrical in
shape. It is useful in experiments with electro-magnetism.
=Solution.= A fluid composed of dissolved salts; a mixture of liquids
and fluids.
=Sound Waves.= Waves produced in an elastic medium by sonorous
vibration, as in wireless telegraphy.
=Sounder.= In telegraphy, the instrument operated on by the key at the
other end of a line. Various devices are employed to increase their
resonance--as, for instance, hollow boxes. Sounders are generally placed
on local circuits and are actuated by relays.
=Sounder, Repeating.= A telegraphic instrument which repeats a message
into another circuit.
=S-P.= An abbreviation for single pole.
=Spark-arrester.= A screen of wire-netting fitted around the carbons of
arc-lamps to prevent the chips or hot sparks from flying.
=Spark-coil.= A coil for producing a spark from a source of
comparatively low electro-motive force. The induction-coil is an
example.
=Spark, Electric.= The phenomenon observed when a disruptive charge
leaves an accumulator or induction-coil and passes through an air gap.
=Spark-gap.= The space left between the ends of an electric resonator
across which the spark springs.
=Sparking.= The production of sparks at the commutator, between the bars
and the brushes of dynamos and motors. They are minute voltaic arcs, and
should not be allowed to occur, as they cut away the metal and score the
surface of the commutator.
=Spark-tube.= A tube used as a gauge to determine when the exhaustion of
the vacuum chamber, or bulb, of an incandescent lamp is sufficiently
high.
=Specific Gravity.= The relative weight or density of a body as compared
with a standard. Water is usually taken as a standard for solids and
liquids, and air for gases.
=Speed-counter.= An instrument which records the number of revolutions a
shaft makes in a given time.
=Spent Acid.= Acid which has become exhausted. In a battery the acid
becomes spent from combination with zinc; it also loses its depolarizing
power.
=Spring-contact.= A spring connected to one lead of an electric circuit.
It is arranged to press against another spring or contact, which it
opens or closes by the introduction of a plug or wedge.
=Spring-jack.= An arrangement of spring-arm conductors under which plugs
with wires attached can be slipped to make a new connection or to cut
out certain circuits.
=Spurious Resistance.= (_See_ Resistance, Spurious.)
=Standard Candle.= (_See_ Candle, Standard.)
=Standard Resistance.= (_See_ Resistance, Standard.)
=Starting-box.= A resistance or shunt box used for letting current pass
gradually into motors, instead of throwing on the full current at once.
=Static Electricity.= Electricity generated by friction; frictional
electricity, such as lightning; electricity of high electro-motive force
and practically uncontrollable for commercial purposes.
=Static Shock.= A term used in electro-therapeutics for describing the
discharge from a small condenser or Leyden-jar; also the effect produced
by the action of the vibrator of the induction-coil.
=Station, Central.= The building or place in which the electrical
apparatus is installed for the generation of current; the headquarters
of telephone lines.
=Steady Current.= An electric current whose strength is fixed or
invariable.
=Stock-ticker.= An instrument employed to give quotations of stocks by
telegraphic record. A paper tape runs through an electrical machine
which prints on it the figures and letters that stand for stocks and
their values. The whole system is operated from a station located in the
Stock-exchange.
=Storage Accumulator.= (_See_ Accumulator, Storage.)
=Storage-battery.= (_See_ Battery, Storage.)
=Strength of Current.= Amperage; the quantity of current in a circuit.
=Stripping.= The process of removing electro-plating, or thin metal
coatings, from an object before it is re-electro-plated.
=Stripping Liquid.= The liquid in a stripping-bath used for removing
metals from surfaces before re-plating them.
=Submarine Cable.= A telegraphic cable laid at the bottom of the sea or
any body of water.
=Submarine Search-light.= An incandescent light which works under water.
=Sub-station.= A generating or converting plant subsidiary to a central
station, and placed so as to supply current in a district situated at a
distance from the main power-house.
=Subway, Electric.= An underground passageway utilized for carrying
cables and wires.
=Sweating.= A process by which the ends of cables are brought together
and soldered.
=S-W-G.= An abbreviation for standard wire gauge.
=Switch.= A device for opening and closing an electric circuit. Made in
a great variety of forms, such as push-button, telegraph-key, knife
switch, automatic switch, lever switch, rheostat, etc.
=Switch-bell.= A combined bell and switch. The bell is operated when the
switch is opened or closed.
=Switch-blade.= The blade of a switch; a conducting strip connecting two
contact-jaws.
=Switch-board.= A board or table to which wires are led and connected
with cross-bars or other devices by which connections can be made.
=Synchronize.= To agree in point of time; to effect concurrence of phase
in two alternating-current machines, in order to combine them
electrically.
T
=Table-push.= A push-button connected with a call-bell and fixed on a
table for convenience in using.
=Tamadine.= A form of cellulose used for making the filaments of
incandescent lamps. The material is cut into proper shapes, carbonized,
and flashed.
=Tangent Galvanometer.= (_See_ Galvanometer, Tangent.)
=Tape, Insulating.= Prepared tape used in covering the bared ends of
wires or joints.
=Tap-wires.= The conductors in trolley systems that at stated intervals,
take the current from the mains and supply it to the bare feed-wires.
=Telegraph.= A system of electric communication invented by S. F. B.
Morse, in which the dot-and-dash characters are used. There are various
modifications of the system--double (or duplex), multiplex, and
quadruplex--by means of which a number of messages may be sent out over
the same wires at one time. Communication from place to place is had
over wires mounted on poles, or by underground or submarine cables.
=Telegraphy, Wireless.= A system of telegraphy carried on without the
aid of wires, using instead the ether waves of the atmosphere to conduct
the vibrations overhead, and the ground, or earth, as a return. The
present limit of its working is about four thousand miles.
=Telephone.= An instrument and apparatus for the transmission of
articulate speech by the electric current. A magnet is encased in a tube
and is encircled at one end by a coil of fine, insulated wire. A
diaphragm of thin iron is fixed in front of the coil and close to the
end of the magnet. The ends of the coil-wires are connected with a
line, at the other end of which another and similar instrument is
installed. The voice causes the sending diaphragm to vibrate, and these
waves are transmitted to the other instrument, where they can be heard
through contra-vibrations of the receiving diaphragm.
=Telephone, Long-distance.= A telephone of modern construction, in which
the sound-recording mechanism is so sensitive as to make the vibrations
of the voice audible at long distances. It will work satisfactorily at
one thousand or even fifteen hundred miles.
=Terminal.= The end of any open electric circuit, or of any electric
apparatus, as the electrodes of a battery.
=Thermostat, Electric.= An apparatus similar in some respects to a
thermometer, and used for closing an electric circuit when the latter
becomes heated. It is used in connection with automatic fire-alarms to
give warning of fire. For this purpose the metal coil is arranged to
close the contact at a temperature of 125° F. It usually consists of a
compound strip of metal wound in the form of a spiral and fastened at
one end. To this end one terminal of a circuit is connected. The
expansion of the coil causes its loose end to touch a contact-point and
close the circuit.
=Third Rail.= A railway motive system which employs a third rail instead
of an overhead trolley feed-wire. The rail is laid on or under the
surface of the ground and properly insulated. A shoe from the car bears
on the rail and takes up the current.
=Three-wire Circuit.= A system invented by Edison for the distribution,
from two dynamos, of current for multiple arc or constant potential
service. One wire or lead starts from the positive pole of one dynamo,
another from the negative pole of the other dynamo, and between the two
dynamos the central or neutral lead is made fast.
[Illustration]
Now the dynamos may generate a current of 220 volts, and send it, at
this strength, through the outer wires; but if lamps are connected
between either of the outer and the neutral wires, the current, passing
through the lamps, will be reduced to 110 volts.
=Time-ball, Electric.= A ball which, by means of electricity, is made to
drop from the top of a high pole, giving a visual signal for twelve
o’clock or any other hour that may be designated.
=Traction, Electric.= The propulsion of a car or conveyance by means of
electricity.
=Transformer.= In alternating-current systems, the induction-coil by
means of which the primary current, with high initial electro-motive
force, is changed into a secondary current with low initial
electro-motive force.
=Transmission.= The conveyance of electric energy and currents from one
point to another by the proper means of conduction.
=Transmitter.= An instrument which originates the signals which are sent
through a line or circuit. The Morse key in telegraphy and the Blake
transmitter in telephony are examples.
=Tri-phase.= Three-phase.
=Trolley.= A contact-wheel of bronze which rolls under the supply-wire
in an overhead traction system and takes off the current necessary to
run the car motors.
=Trolley-wheel.= The same as Trolley.
=Trolley-wire.= The overhead wire in a traction system which feeds the
current through a trolley-wheel and pole to the motors of a car running
underneath.
=True Ohm.= (_See_ Ohm, True.)
=True Resistance.= (_See_ Resistance, True.)
=Two-wire Circuit.= The single system universally used for light and
power transmission of current.
U
=Undulating Current.= (_See_ Current, Undulating.)
=Uniform Magnetic Field.= (_See_ Magnetic Field, Uniform.)
=Unipolar.= Having but one pole.
=Unit.= The single standard of force, light, heat, magnetism,
attraction, repulsion, resistance, etc.
V
=Vacuum.= A space empty or void of all matter; a space from which all
gases have been exhausted.
=Vacuum Tubes.= Tubes of glass through which electric discharges are
passed after the gases have been partially removed; for example, the
X-ray tube of Röntgen and the Crooke tubes.
=Vibrator, Electro-magnetic.= The make-and-break mechanism used on
induction-coils, or other similar apparatus, in which, through alternate
attractions, an arm or spring is kept in motion.
=Vitriol, Blue.= A trade name for copper sulphate. (Bluestone.)
=Vitriol, Green.= A trade name for ferrous sulphate. (Copperas.)
=Vitriol, White.= A trade name for zinc sulphate. (Salts of zinc.)
=Volt.= The practical unit of electro-motive force; the volume and
pressure of an electric current.
=Voltage.= Electric-motive force expressed in volts--as, a voltage of
100 volts.
=Voltaic.= A term derived from the name of the Italian scientist Volta,
and used in many ways as applied to electrical current and devices.
Formerly the term galvanic was commonly employed.
=Voltaic Electricity.= (_See_ Electricity, Voltaic.)
=Voltimeter.= An instrument for measuring the voltage of a current.
=Vulcanite.= Vulcanized rubber. Valuable for its insulating properties
and inductive capability.
W
=Watt.= The practical unit of electrical activity; the rate of work or
rate of energy. It is a unit of energy or of work represented by a
current of one ampere urged on by one volt of electro-motive force.
The volt-ampere.
The standard of electrical energy corresponding to horse-power in
mechanics.
=Watt-hour.= A unit of electric energy or work; one watt exerted or
expended through one hour.
=Waves, Electro-magnetic.= Ether waves caused by electro-magnetic
disturbances affecting the luminiferous ether.
=Welding, Electric.= Welding by the use of the electric current.
=Wimshurst Electric Machine.= An influence machine for producing high
potential or static electricity. Thin disks of glass are mounted on
insulated bearings and revolved by power. Brushes collect the
frictional electricity, which is discharged into a Leyden-jar or
other form of accumulator. It is of no practical use excepting in
electro-therapeutics.
=Wire, Flexible.= A cord of fine wire strands laid together and
insulated so that it may be easily bent or wrapped.
=Wiring.= Installing wires so as to form a circuit for the conveyance of
current for light, heat, and power.
X
=X-rays.= A curious phenomenon involving the radiation of invisible rays
of light, which have the power to travel through various opaque bodies.
The rays are used in detecting foreign substances in the human body and
for photographing invisible or hidden objects without disturbing their
surroundings.
=X-ray Lamp.= A high vacuum tube lamp whose interior walls are covered
with crystals of calcium or other fluorescent substances, and which,
when exposed to the X-rays, give out a luminous light.
Y
=Yoke.= A piece of soft iron which connects the ends of two portions of
a core on which wire coils are wound. It is located at the ends farthest
from the poles.
The soft-iron bar placed across the ends of a horseshoe magnet to retain
its magnetism.
Z
=Zinc-battery.= A battery which decomposes zinc in an electrolyte,
thereby producing a current.
=Zinc Currents.= Negative currents.
=Zinc-plating.= The employment of zinc in electro-plating.
THE END
Transcriber’s Notes
Inconsistent spelling, hyphenation, etc. have been retained, unless
mentioned under Changes Made below. Technical descriptions have been
kept as printed, even when they seem doubtful, wrong or dangerous.
Depending on the hard- and software and their settings used to read
this text, not all elements may display as intended.
Changes Made
Footnotes and illustrations have been moved outside text paragraphs.
Where letters (such as V or L) are used to denote a shape rather than
the letter, they have been transcribed as [V] or [L] for consistency
with other, similarly used letters such as [U].
Some minor obvious typographical errors have been corrected silently.
Page 108: "called Nobile’s pair" changed to "called Nobili’s pair".
Page 182: "shallacked" changed to "shellacked".
Page 184: "(A, B, and C) and A A, B B, and C C)" changed to "(A, B,
and C and A A, B B, and C C)".
Dictionary: several entries have been moved to their proper
alphabetical position.
Page 334: "modern applications of phenonema" changed to "applications
of phenomena
Page 372: "Coil, Ruhmkoff" changed to "Coil, Ruhmkorff".
Page 382: "Daniells" changed to "Daniell".
Page 396: "graphite a native; form of carbon" changed to "graphite; a
native form of carbon".
Page 401: "Ruhmkoff Coil. (See Coil, Ruhmkoff.)" changed to "Ruhmkorff
Coil. (See Coil, Ruhmkorff.)"