DRAKE'S
ELECTRICAL
DICTIONARY
LOWE
Drake's
Electrical Dictionary
A Compendium of Words, Terms
and Phrases Used in the Electrical
Trades and Electrical Engineering
By
PAUL E. LOWE, M. E.
Assisted by a Corps of Electrical Engineers and
Writers on Electrical Subjects
CHICAGO
FREDERICK J. DRAKE & CO.
Publishers
UG
Copyright 1915
By Frederick J. Drake & Co.,
Chicago
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PREFACE
The prime object of DRAKE'S ELECTRICAL DICTION-
ARY is to bring together for convenient reference the
words, terms and phrases used in the electrical world.
The tremendous growth in interest in the electrical
arts, trades and sciences makes some method of quick
reference a practical necessity. It is hoped that the
manner of presentation "followed in this book will
prove to be most advantageous.
Many practical difficulties arise in arranging all
words and phrases alphabetically. The single words
fall into place naturally enough, but in placing the
phrases the question of which word of the phrase is
to have the alphabetic position is important. The gen-
eral plan of using the first words of all phrases has
been adopted. Thus an endless number of annoying
cross references have been avoided.
In any field of science in which growth has been and
continues to be so rapid, it is only natural that words
and terms are not absolutely fixed. Without making
the work too voluminous, however, we have endeavored
to include all those words and terms in common use,
though many are used interchangeably.
Every effort has been made to produce a book of the
greatest practical utility to every one who has any in-
terest in the subject of electricity.
3O2QPO
ELECTRICAL DICTIONARY.
A
A. C. — An abbreviation expressing an alternating
current.
Absolute. — Complete by itself. Independent of any
other element.
Absolute Unit of Current. — A current possessing a de-
gree of strength, and which when transmitted
through a wire which has been curved in the shape
of an arc of a circle of one centimetre radius, will
act on a one-unit power magnetic pole, stationed
at the center of the arc, with a force equal to one
degree. A 10 amperes current.
Absolute Unit of Electromotive Force. — The electro-
motive force unit C. G. S.
Absolute Vacuum. — A void produced by the exhaustion
of all residual gases.
Absorption. — The act of one form of material substance
sucking or drawing in some other form of matter.
The sucking in of water by a sponge or the draw:
ing in of vapors, gases, light, electricity, energy or
heat by any other material substance.
Absorption Power. — A property peculiar to certain ma-
terials by which they draw in gases through their
pores and condense them.
Acceleration. — The increase or decrease of motion or
action. The time period of mutation in velocity.
1
2 ; \ ELECTRICAL DICTIONARY
Accumulated Siectricity.-r-Electricity confined or stored
as in a condenser.
Accumulating Electricity. — Confining or placing elec-
tricity in storage.
Accumulation of Electricity. — The gathering of elec-
tric charges in condensers or Leyden jars. An
electric charge augmented by aid of a device
term an accumulator. A charge produced by the
use of an influence machine. The gathering of
electricity by storage batteries or accumulators.
Accumulator. — A term sometimes used to designate a
current accumulator. A condenser, a Leyden jar,
a storage battery.
Acetometer or Acidometer. — A graduated hydrometer
used to ascertain the strength of acetic acid or
vinegar.
Achromatic Lens. — A lens producing images without
false coloring.
Acidometer. — (See Acetometer.)
Acoustic. — Pertaining to the sense of hearing,or sound.
Acoustic Absorption. — The absorbing by one vibrating
object or mass of the sound-wave energy created
by another vibrating object or mass.
Acoustic Interference. — Mutual influence of sound-
waves upon each other.
Acoustic Synchronizer. — A contrivance employed to
mark the synchronism of two alternating currents.
An acoustic apparatus in which at synchronism
silence is effected.
Actinic. — Pertaining to chemical changes produced by
ELECTRICAL DICTIONARY 3
the sun's rays, or radiators from other sources of
energy.
Actinic Photometer. — A photometer which determines
the intensity of light by the quantity of decompo-
sition which is chemically obtained in it.
Actinic Ray. — Any form of radiating energy having
the property to induce chemical action.
Actinometer. — An apparatus for determining the de-
gree of energy in the chemical effects of light.
Active Coil or Conductor. — A coil or conductor con-
veying a current of electricity.
Active Current. — The active constituent of a current
in an alternating current circuit, in contradistinc-
tion from the wattless component of current.
Active Electromotive Force. — That constituent of the
impressed electromotive force in an alternating
current which is employed to surmount the ohmic
resistance, in contradistinction from the compon-
ent employed to overcome the induced C. E. M. F.
Active Material Storage Cell. — The matter which de-
composes while charging or discharging in a
storage or secondary cell and which performs the
function of storing electricity.
Active Plate of Voltaic Cell. — A term applied to the
zinc and other metallic plates used in voltaic or
primary cells, and which dissolve in the process of
active operation.
Active Polar Surface of Magnet.— The surface of a mag-
net which emits or absorbs the useful flux.
Active Wire. — The section of wire on the armature of
a dynamo which goes through the inducing mag-
4 ELECTRICAL DICTIONARY
netic flux, in contradistinction from the "idle
wire," or the remaining wire which does not pass
through the flux.
Activity. — Power. Rate of performance. Performance
per second in invariable operation.
Actual Efficiency. — Efficiency answering commercial
purposes.
Acute Angle. — An angle less than 90 degrees, or less
than a right angle.
Adapter. — A threaded projection attached to an incan-
descent electric lamp by means of which the lamp
can be screwed to gas fixtures in the place of gas
burner. A device enabling a lamp of any one manu-
facture to be fitted into the socket of the lamp of
every other manufacture. An apparatus contrived
to modify the continuous electric current used in
incandescent service, in order that the mild contin-
uous currents employed in electro-therapeutics may
be obtained.
Adhesion. — An attraction existing between heteroge-
neous molecules in contradistinction from cohesion
or the mutual attraction of homogeneous mole-
cules.
Adhesion, Electric. — The adhesion of two surfaces re-
sulting from the attraction of dissimilar electro-
static charges.
Adhesion, Magnetic. — The adhesion of surfaces result-
ing from magnetic flux.
Adhesive Tape. — A tape rendered adhesive by the ap-
plication of an adhesive insulating material, and
used to protect bare conductors at joints and other
exposed points.
ELECTRICAL DICTIONARY 5
Adiabatic Expansion. — The expansion of a gas in a
chamber whose walls receive no heat from the gas
nor convey any to it differing tlius from isothermal
expansion.
Adjustable Condenser. — A condenser, the capacity of
which is susceptible of variation within prescribed
limits.
Adjustable Resistance. — A resistance, the degree of
which is easily varied within prescribed limits.
Adjustable Rheostat. — A resistance readily adjusted.
Adjustable Vacuum Tube. — A vacuum tube designed
for X-ray examinations; the vacuum in which is
diminishable by heat acting upon a vaporizable
substance.
Adjuster for Lamp Pendant. — A device of any descrip-
tion suitable for making adjustments or changes
in altitude or position of pendant lamps.
Adjusting Cleat. — A cleat susceptible to adjustment
with reference to altitude or alignment.
Adjustment. — Any change in an apparatus which will
insure correct performance of its office.
Adjustment of Relay. — That regulation of a receiving
relay which insures ready response to signals for-
warded over the line.
Aerial Circuit. — The section of a circuit composed of
aerial lines or conductors. An elevated circuit of
wire.
Aerial Conductor. — A conductor erected overhead.
Aerial Line. — A line erected overhead.
Aerodynamics. — The science which treats of the motion
of air and its mechanical effect when in motion.
6 ELECTRICAL DICTIONARY
Aero- Ferric Inductance. — The inductance inherent in a
coil, the magnetic circuit of which is composed in
parts of air and iron.
After Glow. — A fluorescent glow visible in an exhausted
container of glass after removal from electrostatic
influence.
Age-Coating of Electric Incandescent Lamp Chamber. —
A black coating from carbon and other like sub-
stances deposited in the chamber of an incandescent
lamp while in active service.
Aging of Alcohol, Electric. — The artificial aging of
alcohol by subjecting it to the action of ozone gen-
erated by electricity.
Aging of Electric Incandescent Lamp. — A diminishing
by degrees of the capacity of an electric incandes-
cent lamp resulting from either age-coating or im-
pairment of the filament.
Aging of Transformer. — A diminution in the capacity
of a transformer due to its core becoming old.
Transformer fatigue.
Agone. — A line on the earth's surface on which the
magnetic needle points to the true north, the mag-
netic meridian coinciding with the geographical.
Air Blast for Commutator. — A blast of air played upon
the surface of the commutator of an electric dyna-
mo to obviate damaging flashes.
Air Blast Transformer. — A transformer which is kept
cool by the application of an air jet.
Air Churning. — The motion of the air contiguous to the
armature of a dynamo or motor while rotating, oc-
casioning a loss of energy.
Air Core Solenoid. — A solenoid whose sole core is air.
ELECTRICAL DICTIONARY 7
Air Gap.— Any gap or aperture in a magnetic circuit
which contains air only.
Air Gap Commutator. — The air space between the parts
of contaction in an air-insulated commutator.
,
Air Insulation. — Insulation procured by the action of
air.
Air Pump. — A contrivance employed to withdraw the
air and other gases from a vessel.
Air Resistance of Dynamo. — The mechanical resistance
opposed by the surrounding air to the rotary mo-
tion of a dynamo.
Air Space. — The space. existing between the polar sur-
face within wiiic'h an armature rotates, and the
surface of the armature itself. The space in a
comb lightning arrester between the opposing sur-
faces.
Alarm Electric. — Any electric contrivance which, work-
ing automatically, directs attention, by the open-
ing and closing of a circuit, to certain occurrences,
i. e. : the movement of doors or windows, the reach-
ing of certain prescribed limits in the rise and fall
of temperature, footsteps in certain places, etc. A
device used to summon a person to a telephone or
a telegraphic instrument.
"Alive." — A term applied to live circuits or wires.
Active circuits or wires.
All-Night Arc Lamp. — An arc lamp with a double
carbon.
Allotropic State. — The property of substances of exist-
ing in two or more conditions which are distinct
in their physical relation, but without change in
8 ELECTRICAL DICTIONARY
their chemical composition, i. e. : the various modi-
fications of carbon.
Alloy. — Any compound of two or more metals, as of
copper and zinc to form brass.
Alternate Currents. — Currents which alternate.
Alternating. — Having a periodical change in direction.
Alternating Arc. — An arc with alternating current. An
arc which receives its supply from an alternating
current circuit.
Alternating Continuous-Current Commutating Machine.
A secondary generator, which by aid of a commu-
tator, is employed to change an alternating to a
continuous current.
Alternating-Current Dynamo-Electric Machine. — A dy-
namo-electric machine which produces in its ex-
ternal circuit currents that alternate.
Alternating-Current Electric Mo-tor. — A motor impelled
by currents that alternate.
Alternating-Current Electro-Magnet.— An electro-mag-
net, the coils of which are traversed by alternating
currents, and whilst continually reversing in mag-
netism, yet maintains a constant attraction for the
armature.
Alternating-Current Phase-Meter.— -An apparatus em-
ployed to determine the phase difference between
two alternating currents.
Alternating-Current Power. — Electric power furnished
with alternating currents. The result of the effi-
cient alternating current force, the energy of pres-
sure under which the current is obtained, and the
power factor.
ELECTRICAL DICTIONARY 9
Alternating-Current Pressure Indicator. — An alternat-
ing current volt-meter.
Alternating-Current Regulator. — A contrivance em-
ployed to regulate the pressure of an alternating
current generator, with a view to maintaining con-
stancy. A regulator employed to govern the
strength of an alternating current.
Alternating-Current Transmission. — Transmission of
power by the use of alternating currents.
Alternating Currents. — Currents flowing in opposite di-
rections and alternating. Currents which reverse
their direction periodically.
Alternation. — A change of direction. A change of di-
rection by an electro-motive current. One vibration
instead of an entire cycle or a double vibration.
Amalgam. — A compound of mercury or quick silver
with any other metal.
Amalgam, Electric. — A substance used to cover the rub-
bers of frictional electric machines.
Amalgamate. — To convert into an amalgam.
Amalgamation of Zinc. — A salt of mercury solution
used in amalgamating the zincs of voltaic batteries.
Amber. — A yellowish, resinous substance found as a
fossil in alluvial soils.
American Morse Code. — The telegraphic code invented
by Morse, and used almost exclusively in the
United States.
American Wire Gauge. — The name by which the Brown
& Sharpe wire gauge is known, in which the diam-
eter of the largest wire, No. 0000, is 0.46 inches,
and wire No. 36, 0.005 inches, and all other diam-
eters progress geometrically.
10 ELECTRICAL DICTIONARY
Ammeter. — Any sort of galvanometer which can meas-
ure the strength of currents in amperes directly.
Amorphous. — Devoid of definite crystalline form.
Amperage. — The num'ber of amperes which pass
through a circuit in a stated time.
Ampere. — The accepted unit of electric current. A
flow of electricity at a rate which transmits one
coulomb per second. The current which could pass
through a circuit that offered a resistance of one
ohm under a one-volt electro-motive force.
Ampere-Hour. — A unit of quantity equal to the amount
of electricity transmitted by one ampere flowing
during one hour.
Ampere-Hour Efficiency of Storage Battery. — The rate
between the ampere-hours consumed from and
those supplied to a storage battery in a cycle of
charge and discharge.
Ampere-Turn. — A unit of magneto-motive force equal
to the force resulting from the effect of one am-
pere passing around a single turn of wire.
Ampere's Rule for Deflection of Needle. — The deflection
of the north-seeking pole of a magnetic needle by a
current at the left of an object assumed to be
facing the needle from a point in the current.
Amyloid. — A material used itf making incandescent
lamp filaments and which is obtained by subjecting
cellulose to the action of sulphuric acid. A cellu-
lose parchment.
Amyloid Filament. — A filament made of amyloid.
Analysis. — The resolution of any object into its con-
stituent or original elements in order to determine
its composition.
ELECTRICAL DICTIONARY 11
Analysis Electric. — The resolution of a compound sub-
stance into elementary constituents by electrical
process in order to determine its composition.
Anchored Filament. — A means providing for the sup-
port of an incandescent lamp filament at its center
in order to obviate injury by too violent vibration.
Anemometer. — An instrument for measuring the force
and velocity of the wind.
Anemometer, Electric. — An instrument for recording
"the force and direction of the wind by use of elec-
tricity.
Aneroid Barometer. — An instrument for measuring at-
mospheric pressure, the action of which, depends
upon the varying pressure of the atmosphere upon
the elastic top of a metallic box from which the air
has been exhausted.
Angle. — The difference in direction of two lines in the
same plane that meet in a point or that would meet
if sufficiently extended.
Angle of Lead. — The forward angular departure from
the established position, which the collecting
brushes must be required to undergo on commu-
tator of a continuous current generator, to the end,
that quiet commutation may be obtained.
Animal Magnetism. — A term applied to the phenomena
of hypnotism, mesmerism, etc.
Annealing. — A process for softening metals by first
heating and then permitting them to cool gradu-
ally.
Annealing, Electric. — An annealing process by means of
electric heat instead of heat produced in the or-
dinary way.
12 ELECTRICAL DICTIONARY
Annunciator Board. — A board equipped with annunci-
ator drops.
Annunciator Drop. — A signal, which when it drops, an-
nounces the closing or opening of the circuit of
an electro-magnet connected with the annunciator.
Annunciator Wire. — Insulated wire of a kind adaptable
to annunciator circuits.
Anode. — The positive pole of an electric battery, or
preferably the path by which the current passes
out and enters the electrolyte on its way to the
other pole; opposed to the cathode.
Anomalous. — Deviation from a general rule. Abnor-
mal. Irregular.
Anomalous Helix. — A helix wound in such manner as
to create an anomalous magnet.
Anomalous Magnet. — A magnet having more than two
free poles.
Anomalous Magnetization. — The magnetization which
the vibrating discharge of a Ley den jar or conden-
ser produces. Magnetization from which more than
two free poles in a magnet result.
Answering Jacks. — The jacks in a panel of a telephone
switchboard which are connected with those sub-
scribers whose calling drops are in the same panel,
in order that each call may be promptly answered
at a contiguous jack.
Anti-Induction Telephone Cable. — A telephone cable
which, by reason of a particular arrangement of
its conductors, neutralizes the effects of induction
caused by neighboring circuits. A telephone cable
which is protected from the effects of electrostatic
ELECTRICAL DICTIONARY 13
induction from adjacent circuits by a covering of
metal which is grounded at fitting intervals.
Antimonious Lead. — A compound of lead and antimony,
which, being proof against the action of a charging
current, is used for the grid of a storage battery.
Aperiodic. — Not possessing periodicity. Attaining re-
pose without vibrations.
Aperiodic Galvanometer. — A galvanometer the needle
of which attains repose without vibrations. A
dead-beat galvanometer.
Apparent Electro-motive Force. — The apparent acting
of the E. M. F. in a circuit, as measured by the
drop of pressure occasioned by the resistance of
the circuit, and the force of current flowing
through it.
Aqueous Solution. — Substances dissolved in water.
Arc. — A segment of a circle. A voltaic arc.
Arc. — To discharge in voltaic arc form.
Arc-Circuit Cut-Out. — A cut-out used in a series arc-
light circuit to obviate the breaking of the whole
circuit in the event of the extinguishment of any
one lamp.
Arc-Lamp, Electric. — An electric lamp which derives
its light from the voltaic arc. An incandescent
lamp used in observatories to light the circles of
telescopes and other instruments.
Arc-Lamp Hanger. — A board from which an arc-lamp
hangs and is equipped with electric connections.
Arc-Lamp Spark-Arrester. — A gauze protector enclos-
ing the arc, to guard against fire where arc lamps
are used in dangerous proximity to combustible ma-
terfals, as in store windows.
14 ELECTRICAL DICTIONARY
Arc-Light. — The carbon voltaic arc light.
Arc-Light Generator. — A dynamo electric machine
which supplies arc-light circuits with the current.
Arc-Light Projector. — An arc lamp provided with a re-
flector for obtaining a beam of approximately par-
allel rays of light.
Arc Plug-Switchboard. — A -switchboard equipped with
spring-jacks contacts and which connect -with the
terminals of various circuits and plug switches con-
nected to dynamo terminals, so that the connection
between any dynamo and any circuit can be made.
Several circuits connected to the one dynamo, or
several dynamos located in the same circuit.
Arc Standard of Light. — A standard obtained by
means of the photometer, determining the inten-
sity of the light which is given out by a certain
predetermined crater area of the positive carbon
of a carbon arc.
Aerometer. — An instrument for measuring the speci-
fic gravity of fluids.
Areometry. — The act of measuring the specific gravity
of fluids.
Armature. — A body of iron or other material suscep-
tible to magnetization and which is placed on or
contiguous to the poles of a magnet. That part of
a dynamo electric machine termed: the armature.
Armature Bars. — Heavy conductors used for armature
windings. Heavy copper bars used instead of the
usual wire windings on large drum armatures, and
in form of rectangular cross-section strips.
Armature Binding Wires. — Wire coiled on the outside
of the armature wires to preclude the separation,
ELECTRICAL DICTIONARY 15
by centrifugal force of the armature wires from the
core.
Armature Bore. — The space allowed for the rotation of
an armature between the pole pieces of a dynamo.
Armature Core. — The body of laminated iron which
carries the coil conductors of dynamos and motors.
Armature Loop. — The single conducting loop on a dyna-
mo armature.
Armature of Dynamo. — An iron core around which is
wound coils of insulated wire. That part of a dyna-
mo which generates useful currents or differences
of potential. The part of a dynamo which rotates
between the field magnets or pole pieces. That part
of the dynamo which generates E. M. Fs. by the
magnetic flux successively filling and emptying the
coils.
Armature Pinion. — A wheel with teeth attached to the
armature shaft of a surface car motor, whose func-
tion is to engage the teeth of the reducing gear.
Armature Pockets. — Spaces allowed in the core of an
armature to receive the armature coils.
Armature Projections. — The sections of an armature
core which intervene between the slots and pockets.
Armature Reaction. — The reactive magnetic effect, re-
sulting from the action of the current in the arma-
ture of a dynamo, on the magnetic circuit of the
machine.
Armature Slots. — The slots in an armature core in-
tended to receive the armature coils.
Armature Spider. — A frame-work of metal attached
with keys to the armature shaft and equipped with
16 ELECTRICAL DICTIONARY
arms projecting radially and serving to hold the
armature cores solidly.
Armature Stampings. — Stampings of sheet iron em-
ployed for the core discs on laminated armature
cores.
Armature Varnish. — A varnish with insulating prop-
erties used on armature windings to increase their
resistance against friction and moisture.
Armored. — Protected by armor, as of cables protected
by sheathing.
Artificial Illumination. — Light obtained from artificial
sources.
Astatic. — Having no magnetic power of direction.
Astatic Galvanometer. — A galvanometer equipped with
an astatic needle.
Asynchronous. — Happening or acting without simul-
taneity.
Asynchronous Alternating-Current Motor. — A motor,
the speed of which is not simultaneous with that of
its driving generator ; the two machines having an
equal number of poles.
Atmosphere. — The entire mass of aeriform fluid sur-
rounding the earth. The weight or pressure of gas
or fluid on a unit of surface: 14.73 pounds per
square inch at sea level.
Atmospheric Electricity. — Electricity free in the atmos-
phere.
Atom. — An ultimate particle of matter — the smallest
particle of simple matter.
Atomic. — Pertaining to or consisting of atoms.
Atomize. — The separation with an atomizer of a fluid
into a spray. To reduce to atoms.
ELECTRICAL DICTIONARY 17
Attachment Plug. — A plug introduced into a screw
socket, or spring jack, to facilitate the connection
of lamps, etc., to a circuit.
Attract. — To draw to.
Attraction of Gravitation. — The attraction of force by
which all bodies or particles of matter in the uni-
verse tend toward each other. The attraction of
the earth which causes all bodies of lesser mass
within its influence to fall upon it.
Attractions and Repulsions of Currents. — The attrac-
tion or repulsion exerted by active circuits upon
one another, due to the mutual action of their mag-
netic fields.
Aurora. — A luminous meteoric phenomenon appearing
only in the night, displaying itself in streams and
flashes of light, ascending toward the zenith from a
•dusky bank a few degrees above the northern hori-
zon.
Aurora Australis. — A light similar to the Aurora Bore-
alis, appearing in the southern skies.
Aurora Borealis. — The northern light.
Automatic Make-and-Break. — A contrivance which en-
ables the to-and-fro movement of the armature of
an electric magnet to make and break its circuit
automatically.
Automatic Overload- Switch. — An automatic electro-
magnetic switch introduced in a circuit which
causes it to open automatically when the discharg-
ing current surpasses a fixed, safe limiting force.
Automatic Regulation of Dynamo — Electric Machine. —
That regulation of a dynamo electric machine
which automatically maintains, invariable, the
18 ELECTRICAL DICTIONARY
strength of current, or the potential difference at
the terminals.
Automatic Regulation of Motor. — That regulation of a
motor which preserves its speed constant.
Automatic Circuit-Breaker. — A contrivance by means
of which a circuit it automatically opened when
carrying an excessive current.
Automatic Cut-Out for Storage Battery. — An automatic
electro-magnetic switch, introduced into a storage
battery's charging circuit, in order that the charg-
ing circuit may be opened in case the current fails
to enter the batteries.
Automatic Fire-Alarm. — A device so adjusted as to
telegraph automatically an alarm of fire from any
place when its temperature is increased above a
certain degree.
Automatic Telephone Exchange. — A telephonic ex-
change operated upon a system which enables the
subscribers to communicate with each other in-
dependent of an operator.
Automatic Telephone Hook. — A telephone switch which
operates automatically when the receiver is taken
off or hung upon it.
Automatic Time Cut-Out. — A contrivance for automat-
ically cutting a translating device or a source of
electric power from a circuit after the expiration
of a certain predetermined time.
Automobile. — Containing the power of self movement.
Automobile Torpedo. — A torpedo containing the power
to propel itself.
Auxiliary Bus. — An auxiliary pressure to which a cen-
ELECTRICAL DICTIONARY 19
tral station bus-bar is connected. Not the main
station pressure ; but one differing from it.
Average Efficiency of Motor. — The efficiency of an elec-
tric motor founded on its mean load. The ratio of
a motor's performance in a specified time to the
electric power it has consumed in the same time.
Average Life of Incandescent Lamp. — The average
length of time that a number of incandescent
lamps, on a circuit of specified pressure, will burn
without breakage.
B. S. G. — An abbreviation of British standard gauge.
B. & S. W. G. — An abbreviation of Brown and Sharp 's
wire gauge.
B. T. U. — An abbreviation of British thermal unit.
B. W. G. — An abbreviation of Birmingham wire gauge.
Back Pitch. — The pitch backward of the windings of an
armature.
Back-Turns of Armature. — Turns of an armature cur-
rent which have a tendency to demagnetize the
field. Back ampere turns.
Backward Pitch of Armature Windings. — A pitch in-
variably left-handed when viewed from commuta-
tor side.
Bad Earth. — A name given to a bad ground, or an earth
connection with a comparatively strong electric re-
sistance.
Baking Oven, Electric. — A bake oven heated by elec-
tricity.
20 ELECTRICAL DICTIONARY
Balance Photometer. — A photometer founded on the
dissolution of iodide of nitrogen by the process of
light action.
Balanced Armature. — An armature having its weight
apportioned with regularity as referred to its axis
of rotation. An armature set in order by the use
of additional weights, so that its weight is appor-
tioned uniformly as referred to its axis of rotation.
Balanced Load. — A load uniformly apportioned to two
or more generating units as observed in the poly-
phase systems of distribution, or the three-wire,
five-wire, multiple.
Balanced Polyphase System. — A polyphase system with
all its branches proportional with reference to their
electro-motive force and phase.
Balanced Resistance. — A resistance arranged in a
bridge in such a manner that it will be balanced
by the residuary resistance in the bridge.
Balancing Coil of Armature. — A subsidiary field-wind-
ing in series with an armature with its magneto-mo-
tive force equal and opposite to that of the arma-
ture current, obtaining zero as the total magnetic
effect upon the field, leaving the field flux un-
changed no matter what the load.
Balancing Resistance for Dynamos. — A governing re-
sistance possessing a range adequate to the balan-
cing of one dynamo against another with which it
is worked in parallel.
Bank of Lamps. — An assemblage of electric lamps to-
gether in a common structure, ordinarily with a
view to acquiring a load.
Bank of Transformers. — An assemblage of transformers
together in a common structure, ordinarily with a
ELECTRICAL DICTIONARY 21
view, either to acquire a load, or to modify the
pressure.
Bar Armature. — An armature the conductors of which
are constructed of bars-.
Bar Electro-Magnet. — An electro-magnet with its core
presenting the appearance of a straight bar or
rod.
Bar Windings. — Armature windings constructed of
copper bars.
Bar- Wound Armature. — An armature the conductors of
which have the shape of bars.
Bare Carbons. — Arc light carbons which are not electro-
plated with copper.
Barometer. — An instrument for determining the weight
or pressure of the atmosphere.
Barometric Column. — A column ordinarily of mercury,
about 30 inches in perpendicular, supported in a
barometer by the pressure of the atmosphere.
Bar Winding of Armature. — A winding composed of
copper bars joined together at their extremities and
insulated.
Basis Metal of Electro-Plating. — A metal upon the sur-
face of which a deposit is to be made by electro-
plating.
Battery. — A term often applied to an electric battery.
Battery Gauge. — A movable galvanometer appropriate
for common battery-testing work.
Battery Jar. — A jar employed to hold the electrolyte
of each separate cell of a primary or secondary bat-
tery.
Battery Lamp. — An incandescent lamp which by reason
22 ELECTRICAL DICTIONARY
of its low voltage can be worked by the voltage of
a battery having a few series-connected cells.
Battery Motor. — An electric motor wound in such man-
ner as to admit of operation by a comparatively
low power, such as that of the common battery.
Battery of Generators. — Several generators connected
in such manner as to obtain the action of a single
generator.
Battery Solution. — The fluid or electrolyte of the pri-
mary or secondary cell.
Battery Syringe. — A syringe employed for emptying a
voltaic battery of acids or liquids which have lost
their potency, or for replenishing it with live liquid.
Becquerel Radiation. — A radiation discovered by Bec-
querel, which is invisible and which is given out by
some salts, notably salts of uranium, and which has
the power to permeate many opaque bodies im-
penetrable by ordinary light, and affecting a photo-
graphic plate.
Bega. — The prefix for one billion, one thousand million
or 109.
Beg-Ohm. — A billion ohms. One thousand megohms.
Bell-<Hanger's Joint. — A joint made by looping the ends
of wires into each other.
Bell-Shaped Magnet. — A horse-shoe magnet as if
fashioned from a section of split pipe, the approach-
ed poles being semi-circular.
Belt-Driven Generator. — A generator operated with a
belt instead of a direct or rope-operated generator.
Belt, Electric. — A body belt supposed to consist of vol-
taic or thermo-electric couples and used for certain
assumed therapeutic efficacy.
ELECTRICAL DICTIONARY
23
Belt Speed. — The rapidity of a belt's movement in
transmitting power.
Bichromate Voltaic Cell. — A zinc-carbon couple used
with bichromate of potash and sulphuric acid in
aqueous solution.
Bicro. — The prefix for a one-billionth, a one thousand
millionth of 109.
Bicro- Ampere. — A billionth of one ampere.
Bight of Cable. — One loop or bend' only of cable.
Binding Coils or Binding Wires. — Coils of wire with
which the outside of an armature is bound at right
angles-to it, to obviate the loosening of the arma-
ture coils by centrifugal force while the member is
in rotation.
Binding Post. — A binding screw of metal solidly fas-
tened to a machine to facilitate the making of se-
cure electric connection.
Biograph. — A machine which reproduces on a screen
the actual movements of objects by the exhibition
of pictures in rapid succession.
Bipolar. — Possessing two poles.
Bipolar Armature-Winding. — An armature-winding
adaptable to service in a bipolar field.
Bipo Armature-Winding. — An armature-winding adapt-
able to service in a bipolar field.
Bipolar Generator. — A dynamo-electric machine having
two poles.
Bipolar Magnetic Field. — A magnetic field consisting of
two opposed magnetic poles.
Birmingham Wire Gauge. — A wire gauge used hi Eng-
land.
24 ELECTRICAL DICTIONARY
Black Electro-Metallurgical Deposit. — A black electro-
metallurgical deposit precipitated from the metal
in a plating bath and due to the use of a current
of excessive strength.
Blake Telephone Transmitter. — A style of carbon trans-
mitter.
Blasting, Electric. — The explosion of powder or other
explosives in a blast by means of electric ignition.
Blavier's Test. — The localizing of a single fault on a
single telegraph line or conductor by means of the
test brought into practice by Blavier, and which is
accomplished by gauging the resistance at one end,
while the other end is alternately freed and
earthed.
Block System for Railroads. — A system of block signals
employed in railroad train service to prevent col-
lisions ; the road being divided into sections of cer-
tain lengths, with towers situated at the end of
these sections, having telegraphic intercommuni-
cation, providing for the display of proper signals,
thereby preventing more than one train or engine
from occupying the same section or block at the
same time.
Blow. — To fuse -a safety fuse.
Blowing a Fuse. — The melting or fusing of a safety
fuse resulting from the passage of the current
through it exceeding the carrying capacity of the
strip.
Blowing Point of Fuse. — That degree of current
strength which melts or blows the fuse.
Bobbin, Electric. — A coil of wire, insulated, and adapt-
able to an electric current employed for any pur-
pose— for instance : in energizing electro-magnets.
ELECTRICAL DICTIONARY 25
Bolometer. — A machine to measure minute differences
by means of electricity. A thin wire or strip, the
resistance of which is modified incident radiant
energy.
Bonded Rails. — Rails which are used in an electric sys-
tem as a section of the current, and which are
properly jointed at their ends in order to insure
perfect electric contact.
Bonding Resistance of Rail. — The resistance presented
at the bonded joints of a rail circuit.
Booster. — An auxiliary electric dynamo placed in a par-
ticular feeder or assemblage of feeders in a distrib-
uting system in order to increase the pressure
of that particular feeder or assemblage beyond the
pressure of the rest of the system.
Boring1, Electric. — Making holes in metals with voltaic
arc heat.
Bougie-Decimale. — The standard candle of France.
Bougie-Metre. — The unit of illumination, frequently
termed a lux, and equal, at a distance of one metre,
to the illuminating power of a bougie-decimale.
Box Bridge. — An electric bridge in which the two arms
together with the ascertained resistance, consists
of standard resistance coils inclosed in a box.
Boxing the Compass. — Calling in consecutive order the
names of the points of the compass, beginning at
any given point.
Brake Arm. — A lever by which the power is applied to
a brake shoe, to which it is connected.
Brake Shoe. — A metal casting conforming in shape to
an arc of the car wheel circumference, and which
26 ELECTRICAL DICTIONARY
is pressed against the wheel by the operation of
the connected lever in order to stop the car.
Braided Wire. — A wire insulated with a cover of
braided material.
Branch. — Any conductor in a system of parallel dis-
tribution into which taps and outlets are made.
Branch Block. — A block of porcelain with grooves into
which the terminals or conductors are put to make
a connection to the mains with a pair of branch
wires.
Branch Circuits. — Extra circuits located at points of
a circuit at which the current branches, where some
of the current flows through the branch and the
rest passes through the initial circuit.
Branch Coupling Box. — A coupling box adaptable to
making a connection for house service with the
mains supplying the house.
Branch Cut-Out. — A safety fuse introduced between
two branch wires and the mains from which they
receive their supply.
Branch Fuse. — A safety fuse or branch cut-out.
Branding, Electric. — The heating to incandescence of
a branding implement electrically instead of in the
usual way.
Breadth Coefficient of Armature Coil. — The relation of
the efficient electro-motive force induced in an ar-
mature coil to that which would be induced in a
coil with breadth ; that is to say, if the whole of it
were compressed to occupy the space of a single
turn only.
Break. — Any failure of the continuous conductivity in
a circuit.
ELECTRICAL, DICTIONARY 27
Break-Down Switch. — A panel switch, used for connect-
ing the positive and negative bus-bars in a little
three-wire system in order that it may be trans-
formed into a two-wire system, so that in the event
of a break-down the system can be supplied with
a current from one dynamo only.
Breaking1 Capacity of Switch. — The strength of current
which a switch is capable of interrupting safely, as
distinguished from its carrying capacity.
Breaking Down of Dielectric. — The weakening of a
dielectric under electric pressure which allows dis-
integrating discharges to pass through its sub-
stance.
Breaking Down of Insulation. — The impotency of in-
sulating material manifested in the disruptive pass-
age through it of an electric discharge.
Breaking In. — The interruption of a telegraph message
in transmission between two points by the attempt
of an intermediate operator to use the line at the
same time.
Bridge, Electric. — A device employed to measure an
unknown electric resistance. A contrivance used
to measure unknown resistances by comparison
with adjustable ones.
Bridge-Wire. — A wire in a Wheatstone's Bridge in
which the galvanometer is set.
Bridging-Bell Telephone System. — A telephonic system
of communication where the call bells are arranged
in multiple arc and by which the two-line conduc-
tors of metallic circuit are permanently bridged to
the ground in grounded circuits; thus a call sent
out rings every bell in the line, indicating by means
of a code of signals the particular station needed.
28 ELECTRICAL DICTIONARY
Bright Deposit. — A shining surface of metallic deposit
resulting from a special final process in the electro-
plating of silver.
Brother-in-Law. — A concealed bell, corresponding in
sound with that of the fare indicator, and rung in-
stead of the car indicator bell, by dishonest con-
ductors, when fares have been collected.
Brush Contact-Surface. — The part of the- surface of
a commutator which is at any instant of time in
contact with the brushes.
Brush-Holder Cable. — A stranded conductor used in a
dynamo or motor to obtain direct connection with
the brushes.
Brush Holders for Dynamo-Electric Machine. — Contri-
vances by means of which the collecting brushes of
a dynamo-electric machine are supported.
Brush Rocker. — A contrivance in a dynamo which
serves to shift the brushes on the commutator
from one position to another.
Brush Shifting Device. — A modified style of brush
rocker.
Brushes of Dynamo-Electric Machines. — An assem-
blage of wires in a bundle, narrow piece of metal,
carbon plates or metallic plates slit, which press
against the commutator cylinder, carrying off the
current generated.
Bucking. — A term expressing the action of a street car
when it stops suddenly, as though it had collided
with another car, and resulting from the opposition
between two motors.
Buckled Diaphragm. — A defect in the transmitter or re-
ceiver of a telephone caused by warping of the dia-
phragm.
ELECTRICAL DICTIONARY 29
Buckling. — A warping in the surface of the storage
cell plates due to a too rapid discharge.
Bug. — In quadruplex telegraphy, a term serving to
designate any defect in the working of the appara-
tus. Usually applied to a defect in the working of
any electric apparatus.
"Building-Up" of Dynamo. — The action by which a
dynamo-electric machine, after starting up, speed-
ily attains its maximum E. M. F.
Bullet Probe. — A probe with electric conductors ad-
justed in such manner as to effect the closing of
an electric circuit and the operation of an electric
signal when the probe comes in contact with the
bullet.
Bunched Cable. — A cable having more than one wire
or conductor.
Bunsen Screen. — The screen of a Bunsen photometer.
Buoy, Electric. — A buoy displaying luminous signals
produced by electricity.
Burette. — A graduated glass tube with a small aperture
and stop cock used to deliver measured quanti-
ties of liquid.
Buried Cable or Conductor. — A cable placed under-
ground, directly in the earth, and not in a conduit
or subway.
Burn-Out. — The damage sustained by an armature or
any member of an electric machine resulting from
an excessive current due to short circuit and differ-
ent causes.
Burned-Out Incandescent Lamp. — An incandescent
lamp which, by reason of long continued service,
has lost its capacity to furnish light.
30 ELECTRICAL DICTIONARY
Burning at Commutator of Dynamo. — An arcing effect
at the brushes of a dynamo-electric machine arising
from poor contact or imperfect position, by reason
of which the circuit loses energy and the commuta-
tor segments or brushes are destroyed.
Bus-Bar Connectors. — Connectors used to connect or
unite the ends of bus-bars.
Bus-Bars. — Bars which receive the entire current gen-
erated and which are composed of heavy conduct-i
ing metal and connected directly with the poles
of one or several dynamo-electric machines.
Butt Joint. — A joint made by soldering the wires to-
gether end to end.
Buzzer, Electric. — A call emitting a buzzing sound ob-
tained by the use of a rapid automatic contact-
breaker.
C.
C. G. S. — An abbreviation of centimetre-gramme-second
C. P. — An abbreviation of candle-power.
C. G. S. Units. — Centimetre-gramme-second units.
Cable. — A cable for conveying electricity. A message
sent through an electric cable.
Cable Box. — A box employed to receive and protect i
cable head.
Cable Drum. — A drum in machinery for handling cabl(
and upon which it is wound, keeping it in mos"
convenient shape for shipping, laying, etc.
Cable Head. — A board, rectangular in form, and equip
ped with binding posts and fuse wires, used to re
ELECTRICAL DICTIONARY 31
ceive the wires 'at the point where they enter a
cable in overhead lines.
Cable Tank. — A stout water-tight tank carried on a
cable ship and which serves to hold a section of
cable coil which is ready to lay.
Cable Transformer. — A transformer of alternating cur-
rent, the primary and secondary conductors of
which are formed like a cable covered with an
iron sheath or magnetic circuit.
Cadmium Standard Cell. — A standard voltaic cell
showing an exceedingly low temperature coefficient
of change in E. M. F. and using a cadmium-zinc
couple.
Calculagraph. — A machine for recording the time that
the line is used by a subscriber when communica-
ting by long distance telephone.
Cal-Electric Generator. — A generator the performance
of which is contingent upon the generation of the
electric fluid in the secondary coil of a transformer,
effected by variation of temperature in the iron
core of transformer.
Cal-Electricity. — The electricity in the iron core of a
transformer resulting from change of temperature.
Calibrate. — To ascertain the complete or relative values
of the indications of electrical instruments, i. e. :
voltmeters, electrometers, galvanometers, watt-
meters, etc.
Calibrating. — Ascertaining and designating the values
or indications of a voltmeter, electrometer, galvano-
meter, wattmeter, etc.
Call-Bell, Electric. — An electric bell employed to at-
tract the attention of an operator and advise him
32 ELECTRICAL DICTIONARY
that he is wanted at the instrument for communi-
cation.
Calling Drops. — A drop used to indicate the person
calling and employed in isolated-station switch-
boards.
Calling Plug. — The one of two plugs at a central station
which is put into the jack of a subscriber who is
called for and through which he is signaled to the
telephone.
Calorescence. — The change of heat rays, which are in
an obscure state, into luminous rays by impact with
solid bodies.
Caloric. — A term applied formerly to the principle of
heat or the agent to which the phenomena of heat
and combustion were ascribed.
Calorie. — A unit of heat. The degree of heat necessary
to raise 1 gramme of water 1 degree centigrade.
Calorific Intensity. — The temperature reached in com-
bustion.
Calorimeter. — An apparatus for measuring the amount
of heat contained in bodies. -
Calorimetric Conductivity. — The conductivity of a sub-
stance founded upon the amount of heat transfer-
red in a specified time, without considering the
temperature reached.
Candle. — A unit of photometric energy. The photo-
metric energy equal to the product of a standard
candle burning at a rate of two grains a minute.
Candle-Foot. — A unit of illumination equal at a dis-
tance of one foot to that which is given out by a
standard British candle.
ELECTRICAL DICTIONARY 33
Candle-Power. — The intensity of light given out by a
lucid body calculated by standard candles. The
photometric energy of one standard candle.
Canopy Switch. — A switch located overhead at each end
of a trolley car which enables the motorman to turn
the current on or off the car at will.
Caoutchouc. — A vegetable substance obtained from the
juice of certain tropical trees valued for its superior
insulating properties. Commercial india-rubber.
Capability of Dynamo-Electric Machine. — The maxi-
mum energy in theory, of a dynamo obtained by
dividing the square of its electromotive force by
its resistance.
Capacity of Accumulator. — The product of a storage
battery expressed in watt-hours -or ampere-hours.
Capacity of Condenser. — The quantity of electricity
that a condenser can hold in coulombs when-
charged to a one-volt pressure.
Capillarity. — The rise and fall of liquids in conduits,
the inside diameters of which are very small.
Capillary. — Resembling a hair; fine minute, small in
diameter.
Capillary Attraction. — The cause which determines the
ascent or descent of a fluid in a capillary tube above
or below the 'surrounding fluid.
Capsizing Thermometer. — A thermometer for deep-sea
soundings, used in cable work, the position of
which is reversed or upset when the lead begins
to ascend from the bottom, thereby securing a
record of the temperature.
Car Body. — All that part of a railroad car resting upon
the trucks, and designed for the accommodation of
passengers. A frame-work of wood.
34 ELECTRICAL DICTIONARY
Car Controller. — A contrivance employed to control the
movement of a trolley car and which is placed at
each end of the car in order that the motor can
readily -stop, reverse, and regulate the speed of the
car.
Car Heater, Electric. — A heater deriving its heat supply
from the action of electricity and composed of coils
of insulated wire crossed by an electric current.
Car-Lamp, Electric. — An incandescent lamp used in
street railway cars, and ordinarily supplied with an
anchored filament.
Car Truck. — That part of a car which carries and sus-
tains the weight of the body.
Carbon. — An elementary substance, not metallic, in na-
ture, which predominates in all organic compounds
and occurs in three distinct allotropic forms : black
lead, charcoal and the diamond.
Carbon Brushes for Electric Motors or Generators. —
Artificial carbon plates used as brushes for
dynamos or motors.
Carbon Diaphragm of Telephone. — A light sheet of
metal serving as a diaphragm in some forms of
transmitters.
Carbon Electrodes for Arc Lamps. — The carbons be-
tween which the arc of an electric arc lamp is main-
tained.
Carbon Holder. — A device used in arc lamps to support
the carbon.
Carbon Motor Brush. — A carbon brush used on a motor.
Carbon-Point Lightning-Arrester. — An arrester where-
in the disruptive discharge occurs between opposed
carbon points.
ELECTRICAL DICTIONARY 35
Carbon Rheostat. — A resistance formed of carbon
plates and powder and adjusted so that it can be
modified by pressure.
Carbon Telephone Transmitter. — A telephone trans-
mitter the operation of which is contingent upon
the variation in resistance of a carbon button, or a
quantity of loose granulated carbon, on the back
and forth movement of the diaphragm.
Carbonic Acid Gas. — A gas formed by the uniting of
one part of carbon with two parts of oxygen.
Carbonize. — To convert into carbon by combustion, by
the action of fire or concentrated acids on carbon-
izable substances.
Cardew Voltmeter. — A voltmeter which, by means of a
long fine wire whose expansion, resulting from the
passage through it of the current to be measured,
makes the indication.
Carrying Capacity. — The maximum carrying strength
which a wire is capable of carrying.
Case-Hardening1. — The hardening of the outside of
metals with heat generated by electricity.
Cast Rail-Bond. — A bonding obtained by uniting track
rails in a trolley system with molten iron cast
around all but the upper part of the joint.
Catalysis. — An influence exerted on chemical decom-
position by certain substances, which produce
changes in the affinities of other substances, merely
by contact, and without experiencing any changes
themselves.
Cataphoresis. — The tendency to mix or become equably
diffused as referred to electricity. Electric osmose.
Cataphoretic Electrode. — An electrode which holds in
36 ELECTRICAL DICTIONARY
solution the chemical which is to enter into the
body by cataphoresis. The anode.
Centenary Curve. — The curve or sag formed by the
weight of a wire hanging freely between two
points of suspension.
Cathelectrotonus. — The augmentation of functional
activity produced in a nerve in the vicinity of the
negative electrode or cathode, in the practice of
electro-therapeutics.
Cathode. — That part of a battery by which the electric
current leaves substances through which it passes,
or the surface at which the electric current passes
out of the electrolyte ; the negative pole.
Cathode Rays. — Rays emitted by the cathode or nega-
tive pole of an X-ray tube.
Cathodogram. — A picture obtained by means of the
X-ray.
Cauterization. — The act of searing or burning with fire,
or with a heated object or caustic substance.
Cauterization, Electric. — The act of cauterizing by the
application of an electrically heated wire.
Cautery Battery. — A term in electro-therapeutics ap-
plied to a multiple-connected voltaic battery
suitable for producing incandescence for cauteriz-
ing purposes.
Ceiling Block. — Blocks attached to the ceiling, from
which flexible cords can be suspended and con-
nected with the supply wires of an incandescent
system.
Ceiling Board. — A board attached to the ceiling from
which to hang arc lights.
ELECTRICAL DICTIONARY 37
Ceiling Fan. — A fan suspended from the ceiling and
driven by electric power.
Ceiling Rosette. — An ornamental ceiling block in form
of a rose.
Celluloid Lamp-Filament. — A filament made of carbon-
ized celluloid.
Centi. — A prefix indicating the one hundredth part.
Centi-Ampere. — The one hundredth of an ampere.
Centigrade Thermometer Scale. — A thermometer scale
whose thermometric tube is divided into one hun-
dred equal degrees between the melting point of
ice and the boiling point of water.
Centimetre. — The one hundredth of a metre. 0.3937
inch.
Centimetre-Gramme-Second System. — A system taking
the centimetre as its base for the unit of length, the
gramme for the unit of mass and the second for
the unit of time.
Central. — A term applied to any central telephone of-
fice or exchange.
Central Lighting-Station. — A station where are located
the generators and distributing machinery that
furnish the current to the lamps in a certain dis-
trict.
Central-Station Lighting. — The supplying from a cen-
tral station of the current which lights the lamps
in a manner of houses and structures.
Central Telephone Exchange. — A central office with
which a number of subscribers or telephone sta-
tions are connected. A central exchange with
which a number of local exchanges are connected.
38 ELECTRICAL DICTIONARY
Cement-Lined Conduit. — A conduit constructed with
any suitable material, such as metal, stone or wood,
having ducts whose surfaces are lined with cement.
Centre of Distribution. — Any point in an incandescent
distribution system where the supply current is
branched or distributed radially to mains, sub-
mains or transferring devices.
Centre of Gravity. — That point of a body about which
all its parts are balanced.
Centre of Oscillation. — That point of a body which, de-
scribing the movement of a pendulum, is neither
accelerated nor retarded during its oscillatory
movements by those parts of the pendulum which
are located above or below it.
Centre-Pole Construction. — A system of construction
by the use of poles, and employed in double track
trolley systems; the poles being set between the
two tracks and equipped with bracket arms which
extend over the tracks and from which the trolley
wire is suspended.
Centrifugal Force. — That force by which a body in
rotary motion tends to fly off from the axis of mo-
tion.
Centrifugal Governor. — A device serving to keep con-
stant the speed of a steam engine or other motor
regardless of any changes in its load or perform-
ance.
Centrifuge. — An apparatus employed in the separation
of fluids differing in consistency and of solids from
fluids by centrifugal force.
Centripetal. — Tending toward the center.
Change-Over Switch. — A switch employed in a central
ELECTRICAL DICTIONARY 39
station to change a working circuit from one dyna-
mo, or battery of dynamos, to another.
Characteristic Curve. — A diagram in which the relation
of varying values is represented by a curve. A
curve which shows the peculiar properties of a
dynamo operating under various phases.
Characteristics of Sound. — Peculiarities by which mu-
sical sounds are distinguished one from another,
i. e. : pitch, tone, intensity, quality, loudness.
Charged Body. — A body which is charged with elec-
tricity.
Charging Current. — A current used to charge an accu-
mulator or storage battery.
Chemical Affinity. — The attraction of one atom for an-
other. That force which urges atoms to combine
and produce molecules.
Chemical Change. — The formation of new molecules by
any change in matter following the combustion of
atoms.
Chemical Effect. — That effect produced by atomic com-
bination in which the individual characteristics
and properties of the substances entering into such
combination are lost. A combination of atoms
through which new molecules are formed.
Chemical Photometer. — A photometer which deter-
mines, by the amount of chemical action produced
in a specified time, the intensity of the light to be
measured.
Chemical Separation. — Chemical dissolution or decom-
position.
Chloride Storage Cell. — A term applied to a storage
cell, the plates of which are made of grids of anti-
40 ELECTRICAL DICTIONARY
monious lead molded around small knobs of fused
chloride of lead and which are transformed into
spongy metallic lead and lead peroxide on the
negative and positive plates, when brought under
the action of a charging current.
Choking Coil. — A coil of wire wound in such manner on
a core of iron as to acquire self-induction to a high
degree when employed on alternating current cir-
cuits.
Choking Effect.— The effect resulting from the obstruc-
tion or cutting off of an alternating current by a
choking coil, effected with a smaller loss of force
than it would accomplish as an ohmic resistance
only.
Chronograph, Electric. — An electric apparatus em-
' ployed to measure and register small intervals of
time automatically.
Cigar-Lighter, Electric. — An apparatus employed to
light cigars by electricity.
Cinematograph. — A biograph.
Cipher Code. — A code employing arbitrary words to
represent other words or phrases.
Circuit Breaker. — A device serving to open or break a
circuit.
Circuit, Electric. — The path covered by an electric cur-
rent in its passage through a conductor from its
starting point back again.
Circular Flux. — A term applied to the concentric circu-
lar flux surrounding an active cylindrical con-
ductor.
Circular Mil. — A unit of area taken to measure the
cross-section of wires, or about 0.7854 square mils.
A circle area of one mil diameter.
ELECTRICAL DICTIONARY 41
Circular Millage. — The area of wire or conductor cross-
sections denoted in circular mils.
Circumferential Speed. — The velocity of a point on the
circumference of a revolving wheel or armature.
Clearance. — That space in a dynamo or motor between
the surface of a revolving armature and the polar
surface of the field magnets.
Cleat Wiring. — Fixing electric conductors or wires to
ceilings or walls by the use of adaptable insulating
cleats.
Clockwise Motion. — A motion which when observed
from the face corresponds with the rotary motion
of the hands of a clock.
Clockwork Feed for Arc Lamps. — An arc lamp con-
trivance providing for the feeding of the carbons.
An arrangement of wheel work.
Closed Circuit. — A circuit completed.
Closed-Coil Armature. — An armature whose coils are
not on open circuit while rotating. A dynamo
armature the coils of which are assembled in sec-
tions and so connected with the bars of a commu-
tator as to be continuously connected in a closed
circuit.
Closed-Coil Winding. — A winding providing for the
connection of the armature coils while the machine
is in operation.
Closed Iron-Circuit Transformer. — A transformer hav-
ing a core which makes a completed magnetic cir-
cuit. A transformer which is iron-clad.
Closed Magnetic Circuit. — A magnetic circuit lying en-
tirely in iron or other material which is highly per-
meable by magnetic energy.
42 ELECTRICAL DICTIONARY
Clutch for Arc Lamps. — A form of clutch for arc lamps
to hold carbons.
Clutching Device. — A device used to hold the carbons
in an arc lamp or for holding any object which is
subject to motion.
Coarse Winding of Field Magnets. — The series winding
of a compound wound machine.
Coefficient of Expansion. — The augmentation in the
fractional length of a rod or bar when subjected
to heat ranging from 32 to 33 degrees Pahr. or 0 to
1 degree Cent.
Coefficient of Hysteresis. — The work given out in the
cubic centimetre of iron or any magnetic material
during one cycle of unit magnetic flux density.
The coefficient from which is obtained the hyster-
etic activity when it is multiplied by the volume
of iron, the alternating frequency and the one-
sixth power of the maximum flux density.
Coefficient of Inductance. — A fixed quantity which,
multiplied by the current strength flowing through
a coil or circuit, will numerically stand for the flux
linkage with such coil or circuit resulting from
that current. A term applied at times to coefficient
of self-induction.
Coefficient of Reflection. — The percentage value denot-
ing the ratio of intensity of a reflected ray to that
of an incident ray.
Coercive Force. — The resisting power to changes in
magnetization. The demagnetizing power which
must be employed to completely demagnetize a
magnetic substance, in cyclic magnetization.
Coherer. — 'Conducting particles constituting a semi-
ELECTRICAL, DICTIONARY 43
conducting bridge between two electrodes and
serving to detect electro-magnetic waves.
Coil, Electric. — A coil or spool of insulated wire provid-
ing for the passage through it of an electric cur-
rent.
Coked Core of Incandescent Filament. — A filament for
incandescent lamps, the core of which is electrical-
ly coked carbon and the surface of which is coated
with a carbon deposit by the flashing process.
Coked Filament. — A filament of carbon for incandes-
cent lamps which has been freed from gases and
converted into a variety of coke by being subjected
to electric heat in a vacuum.
Cold Light. — Luminous radiation unattended by ob-
scure radiation. Fire-fly or glow-worm light.
Collecting Brushes of Dynamo-Electric Machine. —
Brushes which press against the commutator cylin-
der of a dynamo, bearing away the current gen-
erated in the armature coils by the E. M. F.
•Brushes which press on the collecting rings of an
alternating current armature.
Collecting Rings for Alternators. — Rings of metal
which are connected to the terminals of the arma-
ture coils in an alternator on which the brushes
that carry off the alternating currents are in con-
tact.
Collectors of Dynamo-Electric Machine. — Brushes
which bear on the commutator cylinder and trans-
late the current generated by rotation of the ar-
mature.
Collectors of Frictional Electric Machine. — The points
of metal which gather the charge from the glass
plate or cylinder of a frictional electric machine.
44 ELECTRICAL DICTIONARY
Collector Rings — An alternator's collecting rings.
Combination Fittings for Chandeliers. — Fittings so ar-
ranged as to permit the use of both electricity and
gas.
Commercial Efficiency. — That energy, termed useful,
produced by any machine, and divided by the total
energy it takes in.
Commercial Efficiency of Dynamo, or Generator. — The
ratio of the useful electric energy of a dynamo de-
livered at its terminals, divided by what it takes
in or the mechanical power required to drive it.
Commercial Efficiency of Motor. — The ratio between
the electric activity taken in at its terminals and
the mechanical activity developed at the motor
pulley.
Commutator. — A device by means of which alternating
currents are changed into continuous ones and vice
versa. A device by means of which the direction
of electromotive currents in one portion of a cir-
cuit is changed in another.
Commutator Bar. — An insulated segment of a commu-
tator.
Compass. — The mariner's compass.
Compass Card. — The card employed in the mariner's
compass and upon which is indicated the four car-
dinal points of the compass : north, south, east and
west, and which is also subdivided into 32 points,
termed rhumbs, and also divided into degrees cir-
cumferentially.
Compensated Alternator. — An alternator serving to
maintain a uniform voltage at a given point of its
circuit under differing loads; the field magnets of
ELECTRICAL DICTIONARY 45
which are called into activity in some measure by
fixed currents taken from a separate generator and
to some extent by currents furnished by the load
current in the armature.
Compensated Voltmeter. — A voltmeter at central sta-
tion connected with the bus-bars so that its indica-
tions are corrected automatically for the pressure
drop in some certain group of feeders or single
feeder, resulting in its readings corresponding to
the pressure furnished to the mains.
Compensated Wattmeter. — A wattmeter wound in such
manner as to insure compensation for the effect of
reaction in a shunt circuit.
Complement of Angle. — What is needed to make the
value of an angle equal to a right angle or 90 de-
grees.
Complete Wave. — Two alternations succeeding each
other or two alternations of a periodically alter-
nating quantity. A cycle.
Component. — One of the several separate forces into
which any one force can be resolved. The separate
forces which united produce a single resulting
force.
Component Currents. — The currents into which it may
be apprehended that a single current can be di-
vided in such manner as to become the equivalent
of the single current.
Component Electromotive Forces. — The two or more E.
M. Fs. into which any given E. M. P. may be re-
solved.
Composite Dynamo. — A dynamo of compound winding.
Composite Excitation. — Any exciting of the field mag-
46 ELECTRICAL DICTIONARY
nets of dynamos in which there has been used more
than a single winding; for instance: series wind-
ings and shut winding.
Composite-Field Dynamo. — A dynamo the field of which
has a composite excitation, or is compound wound.
Compound Winding. — A process by which dynamos and
motors are wound and where both shunts and series
coils are located on the field magnets.
Compound-Wound Continuous-Current Generator. — A
continuous current generator the fields of which
are compound wound, in order to hold the pressure
constant under all loads.
Compound- Wound Motor. — A motor, the field of which
is compound wound, in order to keep its speed con-
stant under all loads.
Concealed Wiring. — Wiring laid in the plaster in the in-
terior of structures or hidden from view by passing
them through conduits.
Condenser. — A contrivance for augmenting the capac-
ity of an insulated conductor by placing it in con-
tiguity to another earth-connected conductor, but
from which it is separated by any intervening body
which will allow electrostatic induction to occur
through it.
Conduct. — To convey electricity through conductors.
To be able to carry an electric current.
Conducting Power for Electricity. — The capacity of a
certain length and area of a regular cross-section :
of an electric conducting material, in comparison
with that possessed by the same length and area of |
regular cross-section of some other material agreed
upon as a standard, as namely : pure copper.
ELECTRICAL DICTIONARY 47
Conductivity, Electric. — A discharge produced by car-
rying the charge off through a conductor touching
the charged body — the opposite of a convective or
disruptive charge.
Conductivity Resistance. — The resistance to an electric
conductor made by a body, or the resistance offered
by a body to the passage of electricity through its
mass.
Conductor. — Any material through which the electric
current will pass. A substance which has the power
to determine the direction which the electric
energy will take in passing through the Ether in
the dielectric environing it.
Conduit, Electric. — A space underground in which is a
number of ducts wherein electric wires or cables
are placed.
Conduit Trolley-System. — A trolley system, single or
double, whose trolley wires are laid in an under-
ground, slotted conduit, and in which a plow or sled
pushed or drawn through the slot is substituted for
the trolley-wheel.
Congelation. — The process of passing, or the act of con-
verting from a fluid to a solid state by the abstrac-
tion of heat. Freezing.
Connect. — To effect electric contact.
Connecting-up. — The process by which an electric cir-
cuit is made.
Consequent Pole. — A magnet pole resulting from the
placing together of two free north or south poles.
A magnet pole perfected at some point other than
the extremities of a magnet.
Consonant Electric Circuit. — A circuit of alternating
current having inductance and resistance, with a
48 ELECTRICAL DICTIONARY
secondary current having capacity, inductance and
resistance in such way as to cause the neutrali-
zation of the inductance of the primary circuit by
the inductance and capacity of the secondary. A
primary alternating-current circuit without chok-
ing effect or reactance, due to the presence of a con-
denser in a secondary circuit, in distinction from
the effect of a condenser introduced directly in the
primary circuit.
Constant Current. — A current which always flows in the
same direction. A current whose strength is not
subject to variation.
Constant- Current Arc-Lamp. — A series connected arc-
lamp.
Constant-Current Circuit. — A circuit the current
strength of which remains constant despite any
changes in resistance.
Constant-Current Dynamo. — A generator with constant
current.
Constant-Current Transformer. — A modification in the
strength of a constant current.
Constant-Potential Arc-Lamp. — An arc-lamp used on in-
candescent or constant potential mains.
Constant-Potential Circuit. — A circuit the potential of
which is maintained nearly constant.
Constant-Potential Dynamo. — A dynamo which supplies
a nearly constant difference of potential notwith-
standing changes of resistance or load.
Constant-Potential Motor.— A motor intended to be
worked with a constant potential current. Often a
motor shunt or compound-wound.
ELECTRICAL DICTIONARY 49
Consumer's Terminals. — The terminals in a system of
electric distribution for house service and belong-
ing to the house and at which the supply company
delivers the electricity.
Contact Breaker. — A device employed to open or break
an electric circuit.
Contact Resistance. — Resistance resulting at the point
of contact of several surfaces.
Contact Screw. — A screw tipped with a platinum or
other contact and serving to close the circuit of
any electric device in the circuit of which it is situ-
ated.
Contacts. — Conducting pieces inserted in electric cir-
cuits with a view to open and close the circuit at
points where it is desirable. A fault in a circuit
resulting from any part of the circuit coming ac-
cidentally in contact with a conducting object. A
metallic cross or back connection between telephon-
ic or telegraphic circuits.
Continuous Current. — An electric current flowing in the
same direction only.
Continuous-Current Arc. — A voltaic arc effected by a
continuous current and differing from that which
results from alternating currents.
Continuous-Current Generator. — A generator which fur-
nishes continuous currents.
Continuous-Current Motor. — A motor worked by con-
tinuous currents.
Continuous-Current Transformer. — A dynamotor or mo-
tor dynamo. A transformer from one to another
continuous pressure and current.
Continuous-Surface Commutator. — A dynamo com-
mutator, the gaps of which instead of containing
50 ELECTRICAL DICTIONARY
air spaces, are filled with insulating material; or
one which has no breaks or gaps in its surface be-
tween adjacent commutator bars.
Continuous Winding. — A term often used to designate
wave or undulatory winding of an armature.
Controller. — A magnet, whose coils, in a system of auto-
matic constant current regulation, are crossed by
the main current and which is used to automatic-
ally put a regulator magnet into or out of the main
current on changes of the current passing. An
electric device for governing a circuit or system.
An electric shunting device for governing the speed
of motors. A controller for street railroad cars.
Controller Resistance. — The resistance used with street
car controllers to start ^nd stop motors or for mod-
ifying their speed.
Controller Switch. — The switch which works the switch
cylinder on a street car controller.
Converging Magnetic Flux. — Magnetic flux which con-
veys from one or more points.
Conversion of Electromotive Force. — Any enhancement
or diminution in the value of an electro-motive
force obtained by the employment of a transformer.
Convert. — To modify or transform an electromotive cur-
rent.
Converted Currents. — Electric currents whose strengths
have been enhanced or diminished by use of a
transformer.
Converter. — A term applied occasionally to a trans-
former.
Convolutions of Wire. — The individual loops or turns
in a coil.
ELECTRICAL DICTIONARY 51
Cooling Surface of Armature. — The part of the sur-
face of an armature from which it radiates into the
environing atmosphere the heat energy in it which
results from the passage of the currents generated
during its revolution.
Co-Phasal. — Having the same phases.
Co-Phasal Alternations. — Alternations having the same
phases.
Copper Bath. — An electrolytic bath holding in electro-
lyzable solution a copper salt, and a plate of copper
forming the anode and put into an electrolyte con-
tiguous to the article to be electro-plated which
constitutes the cathode.
Copper Conductivity Standard. — A metre-gramme wire
of standard conductivity (in accordance with the
rules of the British Institution of Electrical Engi-
neers), with a resistance of 0.1519 international
ohm at 15 degrees C., agreeing with Matthiesen's
standard for hard copper.
Copper Efficiency. — The relation of the electric power
delivered by a copper system to the power de-
livered to that system.
Copper Fuse-Wire Terminals. — Copper terminals to
which the terminals of fuse wires or safety catches
are connected.
Copper Loss. — The loss of energy sustained by the cur-
rent passing through the copper wire of a motor,
dynamo or any conducting system.
Copper Plating. — Plating with copper by the electro
plating process.
Copper Ribbon. — A style of copper strap.
52 ELECTRICAL DICTIONARY
Copper Tape. — Copper straps or bars used for winding
armatures.
Copper-Zinc Accumulator. — An accumulator formed of
a copper and a zinc plate immersed in a solution of
sulphate of zinc.
Coppered Carbons. — Electrolytically copper-coated car-
bons for arc-lamps or batteries.
Cord Adjuster. — A device employed to regulate the
length of pendant cords.
Cord, Electric. — An electric conductor, flexible and in-
sulated and usually containing two parallel wires.
Core Discs. — Discs cut or stamped out of sheet iron and
used for the laminated core of any dynamo electric
apparatus.
Core Losses. — The losses sustained by the core of a
dynamo, motor or transformer resulting from hys-
teresis or eddy currents. The Foucault losses.
Core Losses of Transformer. — The losses in the core of
a transformer due to hysteresis and Faucault cur-
rents. Iron losses in a transformer.
Core Transformer. — A transformer where the wire
windings are placed on the core of iron of which ]
it is formed.
Cored Carbons. — Arc-light carbons having a soft center
of carbon.
Coreless Armatures of Dynamo or Motor. — An armature
of a dynamo or motor which has no iron core.
Corpuscle. — A minute particle or physical atom which
composes large bodies ; not the elementary prin-
ciples of matter, but small simple or compound par-
ticles such as are not dissolved or dissipated by
heat.
ELECTRICAL DICTIONARY 53
Cosine. — A trigonometrical function. The Sine of the
complement of an arc of an angle.
Cosine Law of Illumination. — The illuminative intensity
of a surface illuminated by only one point source,
varies as the cosine of the angle of the rays incident
upon the surface from that source.
Cotangent. — A trigonometrical function. The tangent
of the complement of an arc or angle.
Coulomb. — The unit of electric quantity accepted for
practical use. A quantity of electricity equal to
that which would pass in one second through a cir-
cuit conveying one ampere. The quantity of elec-
tricity which a condenser of one Farad capacity
contains when subjected to the E. M. F. of one volt.
Coulomb Meter. — A meter that measures in coulombs
the quantity of electricity passing through any cir-
cuit.
Counter-Clockwise Motion. — A rotary motion which
observed when facing a clock is opposed in its di-
rection to that of the clock's hands.
Counter-Electromotive Force. — An electromotive force
tending to send out a current in the opposite direc-
tion to that actually emanating from a source. An
electromotive force in an electric motor created by
the revolution of the armature and opposed to the
force generated by the driving current.
Counter-Electromotive Force of Arc. — An electromotive
force created while a carbon voltaic arc is forming
and opposed to that which sustains the arc.
Counter-Electromotive Force or Electrolysis. — A coun-
ter-electromotive force resulting from electrolysis
in the plating bath of an electrolytic cell.
54 ELECTRICAL DICTIONARY
Counter-Electromotive Force of Mutual Induction. — A
counter-electromotive force created by reciprocal
induction between adjacent circuits.
Counter Pressure. — A term occasionally applied to
counter-electromotive force.
Cradle Dynamometer. — A dynamometer with a cradle
which holds the machine to be tested, and the me-
chanical energy which it takes in or gives out is
measured by the torque which the cradle develops
about its axis.
Crater in Positive Carbon. — A cavity in the end of a
positive carbon of an arc lamp which appears after
the lamp has been running a little while.
Creep of Belt. — A term applied to the slipping of a belt.
Creeping of Voltaic Cell. — The deposit or incrustation
due to the efflorescence of salts on the sides of the
porous cup of a voltaic cell, or on the binding posts
or the walls of the container holding the electrolyte.
Creeping of Belt. — The' slipping of a driving belt result-
ing from the driving pulley traveling faster than
the driven pulley.
Creosoting. — A process employed to preserve wood,.
telegraph poles, etc., by injecting creosote into the
pores of the wood.
Crevasse. — A fine split in a magnetized substance used
to determine the magnetic forces on a small needle.
Critical Pressure of a Gas or Vapor. — The lowest point
of pressure which will not admit of the vapori-
zation of a substance in the fluid state by increase
of temperature; but where instead, it changes en-
tirely into gas. The lowest point of pressure where
a gaseous substance when cooled, liquefies in the
ELECTRICAL DICTIONARY
55
presence of its vapor. The pressure above which a
gaseous substance will not liquefy, however much
may be the pressure.
Critical Temperature of a Substance. — A degree of tem-
perature above which a substance, in gaseous form,
will not liquefy, however much pressure may be
applied. The temperature below which a gaseous
substance is subject to liquefaction by pressure, it
being a vapor.
Crookes' Effect. — An effect obtained in high vacuum
tubes, resulting from motions peculiar to heated or
electrified molecules when in high state of radi-
ation.
Crookes' Radiometer. — An apparatus which demon-
strates the action of radiant matter in effecting mo-
tion from the reactionary effects of a stream of
molecules cast off from a number of unequally heat-
ed surfaces which are easily moved.
Crookes' Tubes. — Glass tubes, practically total vacuums
employed to demonstrate the characteristics of the
ultragaseous condition of matter. A term often
applied to X-ray tubes.
Cross Bonding. — The bonding, in an electric railroad
between the ground feeder and the track employed,
in order to secure a good conducting return circuit.
Cross-Connected Dynamo. — A dynamo, which has the
ends of its armature coils connected to correspond-
ing segments around the commutator.
Cross Current. — A current which flows between the ar-
matures of alternating current generators worked
in parallel, and created by differences in magnitude
or phase of the E. M. Fs. in the machines.
56 ELECTRICAL DICTIONARY
Cross, Electric. — Usually a metallic connection occur-
ring between two conducting lines. A fault in any
circuit resulting from the crossing contact of two
wires.
Cross System. — A system which provides for the run-
. ning of wires overhead in order to prevent recip-
rocal inductive perturbation, and which is effected
by the crossing or transposition of the wires on the
pole arms at desired intervals, in contradistinction
to the twist system.
Crow-Foot Zinc. — A zinc like a crow's foot in form and
used in the gravity voltaic cell.
Crucible, Electric. — A crucible adapted to electro-metal-
lurgical operations. A crucible in which to effect
difficult fusions and secure the separation of
metals from their ores or to form alloys, the heat of
a voltaic arc or electric incandescence is used.
Crystal. — The regular form which a substance tends to
assume in solidifying and displaying a solid body
which presents symmetrically arrayed surfaces.
Crystallization. — The process by which a substance in
solidifying through solution OF fusion, assumes the
form of a crystal.
Crystallize. — To take on crystalline form in the separa-
tion from the vaporous or liquid condition.
Cryptoscope. — An apparatus fashioned in form of a
tube of pasteboard having a florescent screen at
one end and which is viewed through an eye-piece
at the other end.
Cupric Electrolysis. — Electrolysis effected in electro-
therapeutic treatment, by copper electrodes, by
which means a salt of copper is conveyed into the
tissues under the anode by catophoric action.
ELECTRICAL DICTIONARY 57
Current Density. — The strength of current which flows
in any part of a circuit divded by the cross-section
area of that section of the circuit.
Current Distribution. — The branching out of electric
currents through a conducting or ramified mass.
Current Efficiency of Storage Battery.— The ratio of the
whole useful electric quantity given out to a work-
ing circuit by a charged storage battery, to the
whole electric quantity used to charge the battery.
Current Electric. — The quantity of electricity, passing
through any circuit, per second, the flow being uni-
form. The rate attained by a quantity of electric-
ity in passing through a circuit. The relation per
second considered in reference to electric terms of
quantity, between the electro-motive force, which
causes the current, and the opposing resistance.
Current Strength. — The quotient, in a direct current
circuit of the whole electromotive power, divided
by the whole resistance. The time-measure of the
flow in a circuit represented by amperes or cou-
lombs per second. The quotient of the whole electro-
motive power, in an alternating circuit, divided by
the resistance.
Current Teaser, Electric. — A coil of fine wire used OD
the field magnets of an electric dynamo or motor,
together with the series coils already wound upon
it, and which is connected to serve as a shunt across
the main circuit.
Current Transformation. — The changing of the strength
of a current by modifying its electro-motive force.
The changing of a direct into an alternating cur-
rent, or vice versa, or the changing of an alternat-
ing current of one phase into a current of many
phases.
58 ELECTRICAL DICTIONARY
Curve of Sines. — A curve which represents at con-
tinuous successive positions the successive values
of the sines of a progressively varying angle.
Cut-Out. — To abstract an electro-receptive device from
the circuit of an electric source.
Cut-Out Cabinet. — Any enclosure of space in a building
arranged for the reception of fuses or cut-outs.
Cutting Lines of Magnetic Force. — The cutting or in-
tersecting of lines of magnetic force or flux by pass-
ing a conductor through such lines or by passing
such lines through a conductor.
Cycle. — Events following in succession, recurring pe-
riodically, the reckoning of periodicity being taken
from any moment of interruption to the next mo-
ment of occurrence.
Cycle of Alternations. — The cycle of an electro-motive
force, current or flux, alternating periodically.
Cyclometer. — An instrument which records the number
of revolutions made by a wheel or any other re-
volving device, or which records the distance cov-
ered by its periphery.
Cylindrical Armature. — A name given to a drum arma-
ture.
Cylindrical Core. — A mass of iron, cylindrical in form
and used for the core of a solenoid or helix. A
mass of soft carbon, cylindrical in form and used
in cored electrodes.
ELECTRICAL DICTIONARY ' 59
D.
D. C. — An abbreviation for direct current.
D. P. Switch. — An abbreviation for double pole switch.
Damped Galvanometer. — A galvanometer the needle or
coil of which comes to repose almost immediately
when moved.
Damped Vibrations. — Vibrations occurring under con-
ditions which enable the swinging or oscillating
motion to immediately assume repose instead of
continuing the to and fro movement when the force
which causes the vibration is removed. Vibrations
of successively decreasing amplitude.
Damper. — A metallic cylinder disposed in such manner
as to nearly or entirely encompass the iron core of
an induction coil for the purpose of effecting a
variation in the intensity of currents produced in
the secondary. A dash-pot furnished to obviate
the too sudden movements of a lever or other mem-
ber of a moving contrivance.
Damping. — The stopping of sudden oscillations without
waiting their cessation after reiterated to and fro
movements. The neutralization of the motive
energy in a periodically moving body by the ap-
plication of impeding forces.
Damping Magnet. — Any magnet serving to check the
motions of a moving object or magnet.
Dash-Pot. — A cylinder partly filled with fluid having
a loosely fitting piston to ease the blow of any fall-
ing weight. A contrivance to obviate too sudden
motion in the movable members of an apparatus.
'60 ELECTRICAL DICTIONARY
Day Load. — A load carried on a machine or at a central
station during the day time.
Dead-Beat. — Damped heavily. That motion of a galva-
nometer needle which describes excited movement
from point to point and returns quickly to repose.
Aperiodic.
Dead-Beat Galvanometer. — A galvanometer whose
needle does not reiterate its to and fro oscillatory
motion, but instead, comes quickly to repose.
Dead Ground or Grounding. — A grounding that will
secure a ground of negligible resistance.
Deci. — A prefix signifying the one-tenth part.
Deci-Ampere. — A tenth of an ampere.
Deflection of Magnet. — The deviation of a magnetic
needle from the true geographical north.
Declinometer. — An instrument for measuring the decli-
nation of the magnetic needle.
Decohere. — To re-establish or recover the normal con-
dition of a coherer.
Decomposition, Electrolytic. — The resolution of a mole-
cule into its composite radicals or into its ultimate
atoms when subjected to the action of an electric
current.
Deflection of Magnetic Needle. — The deviation of a
needle from a point of repose either in the earth's
magnetic field or in that of another magnet and
produced by the influence of the flux of an electric
-current or of a magnet.
Deka. — A prefix expressing ten times.
Deka-Ampere. — Ten amperes.
Deliquescence. — Liquefying in the air. The solution of
ELECTRICAL DICTIONARY 61
a crystalline body by the attraction of moisture
from the atmosphere.
Delivered Power. — The power delivered at one end of
a line, in a system of electrical transmission, in
contradistinction to the power delivered into the
line at the other end.
Delta Current. — In a triphase system the current be-
tween contiguous wires. The ring current.
Delta Triphase-System. — A triphase-system with ter-
minal connection similar in appearance to a tri-
angle or the Greek letter Delta.
Demagnetization. — The act or process of depriving a
magnet of magnetic polarity.
Demagnetization by Successive Reversals. — The act of
abstracting the magnetism from a mass of magne-
tized metal by exposing it to the action of succes-
sive magneto-motive forces, which alternate in di-
rection and are gradually reduced to zero.
Density of Current. — The quantity of current which
flows per-unit-of-area of cross section in any section
of a circuit.
Density of Field. — The quantity of magnetic flux which
flows through any field per-unit-of-area of cross
section.
Depolarize. — To deprive of polarity.
Detector Galvanometer. — Any imperfected pattern of
galvanometer serving to detect the presence of
electric currents.
Diacritical Current. — That strength of a magnetizing
current which will magnetize an iron core to a de-
gree equal to one-half saturation.
Diacritical Point of Magnetic Saturation. — A term set
62 ELECTRICAL DICTIONARY
forth for such value of the co-efficient of magnetic
saturation that its core is magnetized precisely to
one-half of its practicable maximum magnetization.
Diamagnetic. — A property characterizing zinc, anti-
mony, phosphorus, bismuth and other substances
by which they appear to be repulsed when put be-
tween the poles of strong magnets.
Diameter of Commutation. — The diameter at that part
of a dynamo's commutator where the brushes
touch. The diameter of the commutator of an open
circuited armature which is in direct contact with
the collecting brushes.
Diaphragm. — A thin plate or disc of elastic material
well secured at its edges and susceptible to vibra-
tory motion. The porous partition of an endosmom-
eter or of a voltaic cell. A plate with a circular
opening used in instruments to cut off marginal
portions of a beam of light as at the focus of a
telescope.
Diaphragm Photometer. — A photometer whose func-
tional operation is dependent upon the equality of
the effulgence produced on the two halves of a
diaphragm by altering the distances of the light
effects from the diaphragm, or by changing the
inclination of the bright rays on it.
Dielectric. — Any substance through whose mass elec-
trostatic induction is allowed to occur.
Dielectric Hysteresis. — A kind of molecular friction cor-
responding to hysteresis occurring in a dielectric
under changes of electrostatic stress. A certain
property of a dielectric which permits the consump-
tion of energy in reversals of electrification.
ELECTRICAL DICTIONARY
63
Dielectric Hysteretic Impedance. — The apparent com-
ponent of resistance or obstruction in an alternat-
ing current circuit resulting from dielectric hys-
teresis.
Dielectric Hysteretic Lag. — In an alternating current
circuit the lag resulting from dielectric hysteresis.
Difference of Potential. — That property in space relat-
ing to quantity, by which work is performed when
a mass of matter is shifted from one point to an-
other.
Difference of Magnetic Potential. — That property in
space relating to quantity, by which work is per-
formed when a magnetic pole moves in it. The
magnetic performance on a unit magnetic pole in
a trip between two points.
Difference of Thermal Pressure. — A phase used at times
for the variation of temperature existing between
two points in a conducting material which is sup-
posed to produce the flow of heat from the higher
to the lower temperature, through such conductor.
Differential Compound Motor. — A compound motor
wherein the magneto-motive force of the working
current operates in opposition to a like force of the
shunt excitation in order to keep the speed con-
stant under all loads.
Differential Electric Arc-Lamp. — A term used signify-
ing a derived circuit arc-lamp, the lighting magnet
of which consists of a core with series of shunt
coils or of two individual cores opposed to each
other, one containing the shunt winding and the
other the series.
Differential Electro-Magnet. — An electro-magnet dif-
ferentially wound.
64 ELECTRICAL DICTIONARY
Differential Permeability. — In a substance being sub-
jected to magnetization, the differential co-efficient
of flux density to the magnetizing force.
Differential Winding. — A manner of double winding
of magnet coils which results in the opposition of
the two poles to each other.
Differential Winding of Field. — A manner of field mag-
net winding resulting in two exciting currents
exerting opposing magneto-motive forces. A man-
ner of winding which results in the magnetizing
flux of the series coil being opposed by that of the
shunt coil.
Differentially Wound Motor. — A motor compound
wound wherein the shunt coil current opposes in
its magnetizing consequence, the current in the
series coil, so that the difference between the mag-
netizing effects of the two coils is equal to the
efficient magnetizing effect produced.
Diffusion of Magnetic Flux. — The lateral deviation of
magnetic flux from the direct course between the
poles which produce it.
Dimensions of Units. — The exponential values tacitly
assigned to units of length, time and mass.
Dimmer. — A choking coil used in an alternating current
system of distribution for governing the strength
of current flowing through incandescent lamps.
Resistance used to reduce the flow of current
through incandescent lamps.
Dioptrics. — The science which treats of the laws of the
refraction of light.
Dip. — Dip of the needle or magnetic dip. The inclina-
tidn of the magnetic needle.
ELECTRICAL DICTIONARY 65
Diphase-Alternating Currents. — Two individual alter-
nating electric currents with a phase difference of
one-quarter of a cycle. Two-phase currents. Quar-
ter-phase currents.
Diphase Rotary Field. — A magnetic field obtained by
the employment of four or more magnet poles
wound in such manner as to require their polarity
to alternate with changes in the direction of the
current, and in addition, to act as though the field
rotated. A rotating magnetic field effected by di-
phase currents.
Diplex Telegraphy. — A method providing for the trans-
mission of two telegraphic messages over a single
wire and in the same direction simultaneously.
Diplex Telephony. — A method providing for the trans-
mission of two telephonic messages simultaneously
in the same direction and over the same wire.
Dipping. — An electro-metallurgical process in which a
metallic salt is dipped in a solution of resolvable
metallic salt whereby a light deposit or plating of
metal is obtained on its surface. Preparing sur-
faces for electro-plating by dipping them in cer-
tain acid fluids.
Dipping Basket. — A non-corrosive perforated basket
used in electro-plating to hold articles which are
to be dipped in the cleaning solution.
Dipping Hook. — A metallic hook used in electro-plating
to hold the articles which are to be dipped in the
cleansing solution.
Dipping Magnetic-Needle. — A magnetic needle so sus-
pended as to be free only in a vertical plane and
used to ascertain the magnetic inclination.
56 ELECTRICAL DICTIONARY
Direct-Coupled Dynamo. — A dynamo the shaft of whose
armature is coupled directly to the driving shaft.
Direct-Current Dynamo-Electric Machine. — A dynamo-
electric machine which has the capacity to supply
direct currents.
Direct-Current Electric Motor. — An electric motor
which is driven by direct currents in contr-a-dis-
tinction to one driven by alternating currents.
Direct-Current Rotary Transformer. — A term applied
to a rotating secondary generator of continuous
currents.
Direct Reading Galvanometer. — A galvanometer having
the absolute value of the deflection and current
strength directly indicated instead of reckoned.
Direction of Electric Current. — An assumption that an
electric current leaves its source at its positive pole
and re-enters it at its negative pole.
Direction of Lines of Force. — The direction of magnetic
flux.
Direction of Magnetic Flux. — An assumption that mag-
netic flux leaves a magnet at its north-seeking pole
and re-enters it at its south-seeking pole.
Disc Armature. — An armature of a dynamo electric
machine the windings of which are composed of
flat coils maintained on the surface of a disc.
Discharge. — The equalization of differences of potential
by connecting them by a conductor. To equalize
the difference of potential between the terminals
of a condenser by connecting them with a conduc-
tor. The abstraction of a charge from a conductor
by connecting it to the earth or another conductor.
The abstraction of a charge from an insulated con-
ELECTRICAL DICTIONARY 67
ductor by the use of a current of electrified air
atoms.
Disconnect. — To break an electric circuit or open it.
To abstract an electro-receptive contrivance from
a circuit.
Disconnection. — A term used generally to indicate
divers faults occasioned by a circuit accidentally
breaking or becoming disconnected. The pur-
posely opening or breaking of a circuit or the ab-
straction from it of an electro-receptive contriv-
ance. An interruption in the continuity of a cir-
cuit.
Disintegration of Storage Battery Plate. — The gradual
wearing and falling away of the live material of
a storage battery plate from the perforations of the
grid.
Dissipation Function. — A function signifying the rate
at which the passage of an electric current through
a conductor produces heat.
Dissipation of Energy. — The scattering, loss or waste
of usable energy.
Dissonance, Electric. — Electrical discord. A term ap-
plied to alternating electro-motive forces with op-
posed phases, and signifying the opposite of elec-
tric consonance.
Distillation, Electric. — The distilling of a liquid by the
employment of electricity which, by electrifying
the liquid, assists the effects of the heat.
Distorsion. — The state of being wrested or twisted out
of natural shape or position produced in an entity
by the action of a 'stress.
68 ELECTRICAL DICTIONARY
Distorsion of Magnetic Field. — An alteration in the
direction and dispensation of the magnetic flux in
the field of a dynamo armature, effected by the
magneto-motive power of the armature current.
Distributing Board. — A term given to a cross connect-
ing board in a telephonic or telegraphic system.
A board which is the terminating point for the
wires from a telephone switchboard and where con-
nection with the circuit wires is effected. An in-
sulating board equipped with screw-connecting
pieces and serving in a distributing 'system to con-
nect branch circuits to mains, with or without fuse
cut-outs.
Distributing Box. — A box so equipped as to be easily
able to change the connections of distributing cir-
cuits with the source from which they receive their
supply. A box located at a point of distribution
and containing the fuses appertaining to that sec-
tion of the distributing system.
Distributing Mains. — The mains used in a feeder system
of parallel conductors.
Distributing Center. — A point of ramification. The
center of distribution in a distributing system.
Distribution of Electricity by Commutating Transform,
ers. — A system of distribution employing motor
generators whose field magnets and armatures do
not revolve as a special commutator is used to
charge the polarity of the magnetic circuit.
Distribution of Electricity by Means of Transformers. —
A system whereby the electric energy is conveyed
by means of continuous currents which are trans-
mitted over the line to conveniently located stations
at which motor dynamos do duty for transformers.
ELECTRICAL DICTIONARY
Distribution of Electricity by Motor Generators. — A
system of electric distribution wherein an uninter-
rupted electric stream of high potentiality, dis-
tributed through the main line, is employed at the
place where its energy is to be made use of, to drive
a motor, which drives a dynamo, the current of
which serves to energize the electro-receptive de-
vices.
Diurnal Load-Factor. — The ratio between the whole
number of units delivered from a station during
twenty-four hours to the number which would
have been delivered had the work of the plant been
performed under its maximum load during that
time.
Divergent Flux. — A flux whose intensity diminishes by
divergence or diffusion as it proceeds along its
course.
Door-Opener, Electric. — An electro-magnetic contriv-
ance used to open a door from a distance.
Door Push. — A contact, as in a burglar alarm system,
which opens or closes by the opening or closing of
a door or window and sounds the alarm from a
distance.
Double-Armature Windings. — Two armature windings
fixed to a core symmetrically, with their respec-
tive ends connected to alternate commutator bars.
Double-Balance Relay. — Two relays, in a closed current
telegraph alarm system, which are connected in
series, one serving to close a local circuit in the
event the main line current weakens noticeably,
and the other serving to close a local circuit if the
main line current should strengthen noticeably.
70 ELECTRICAL DICTIONARY
Double-Break Switch. — A two-pole switch. A switch
serving to break a circuit at two points in which
it is distinguished from a switch which breaks a
circuit at only one place.
Double-Carbon Arc-Lamp. — An arc-lamp provided with
two sets of carbon electrodes which enable it to
burn all night without being replenished with
other carbons; the two sets being so disposed that
when one set burns out the current is switched
automatically to the other set.
Double-Contact Push. — A push having two contacts and
so contrived that pressure upon it opens one con-
tact and closes the other.
Double-Deck Switchboard. — A switchboard having two
rows of switches and instruments, one over the
other.
Double-Filament Lamp. — An incandescent lamp often
used as a side light for a vessel, and supplied with
two carbon filaments, adjusted so that in case one
should break, the other will continue to burn. An
incandescent lamp requiring double the pressure
of an ordinary lamp by reason of its having two
filaments connected in series.
Double-Pole Cut-Out. — A cut-out which, by a single
action, cuts out both the positive and the negative
leads. Two safety fuses occupying the same holder
and being respectively connected to the positive
main and negative main.
Double-Pole Switch. — A switch serving to break the
circuit -of both the positive and negative leads at
the same instant.
Double-Reduction. — A velocity reducer for gear wheels
ELECTRICAL DICTIONARY 71
using two gear wheels and two pinions, or one in-
termediate shaft.
Double-Reduction Car-Motor. — A car-motor equipped
with a double reduction or an intermediate gear
shaft between the car wheel and motor shaft.
Double-Throw Switch. — A switch which can be thrown
into either one of two contacts. A throw-over
switch.
Double-Trolley. — In a double over-head system, two dis-
tinct trolleys carried on the same car and running
over two distinct wires which make a metallic cir-
cuit.
Double-Truck Car. — A car resting on two separate
single trucks, a plan adopted for long cars to in-
sure safety and convenience in turning short
curves.
Double- Winding of Armature. — An armature winding
supplied with two distinct windings or sets of coils*
the windings being insulated from each other and
connected to the commutator at every other seg-
ment, providing thus for the brushes to repose
upon corresponding segments, connected with each
winding, and thereby allowing each winding to
supply one-half the current strength with an ac-
companying diminution in the inductance of each
circuit.
Double- Wire Moulding. — A moulding providing for the
accommodation of two wires each in a distinct
groove.
Drag of Magnetic Field. — A term applied at times to
the torque or electro-dynamic force resulting from
the presence of an active conductor in a magnetic
field,
72 ELECTRICAL DICTIONARY
Draw-Bar. — The bar which connects a locomotive with
its train.
Draw-Bar Pull. — The pull exerted by a locomotive at
its draw-bar as discriminated from its motor pull.
Driven Pulley. — A pulley to which the motion is given
by a driving shaft.
Driven Shaft. — A shaft operated by a driving pulley
belt.
Driving Pulley. — The pulley of a machine located on
the driving shaft.
Driving Pulley of Motor. — A pulley mounted on the
shaft of a motor or a pulley which conveys the
mechanical power of a motor.
Driving Shaft. — A shaft connected immediately with
a prime mover.
Drop. — A word signifying the drop of potential, pres-
sure or electro-motive force. The fall of potential
occurring in an active conductor, due to its resist-
ance.
Drop Annunciator. — An electro-magnetic annunciator
which, when energized, sets free a shutter and
allows it to drop.
Drop of Potential. — The decrease of potential equal in
any section of a circuit to the product of the re-
sistance and the current strength in that section
of the circuit.
Drop of Voltage. — The difference of potential of any
section of a circuit.
Drum Armature. — A dynamo armature with coils
wound over the exterior part of a drum in the di-
rection of its length.
ELECTRICAL DICTIONARY 73
Dry Battery. — Several distinct dry voltaic cells con-
nected in a manner to act as a single source.
Dry Transformer. — A transformer air-insulated; being
thus distinguished from an oil-insulated trans-
former.
Duct. — A space in a conduit underground for a single
wire or cable.
Dummy Moulding. — An ornamental moulding, not in-
tended to receive a wire ; but placed on the ceiling
to preserve the symmetry of the decorative ar-
rangement which includes the useful mouldings
into which wires are laid.
Duplex Cable. — A cable consisting of two separate con-
ductors paralleling each other.
Duplex Telegraphy. — A system providing for the trans-
mission of two telegraphic messages over a single
wire simultaneously in opposite directions.
Duplex Transmission. — The transmission of two tele-
graphic or telephonic messages simultaneously over
the same wire in opposite directions.
Duplex Wire. — An insulated conductor having two dis-
tinct parallel wires.
Dust Telephone-Transmitter. — A style of microphone
transmitter supplied with a carbon dust contained
in a conveniently arranged box which is connected
with the transmitter's terminals.
Dynamic Electricity. — A term applied to current elec-
tricity as distinguished from static electricity.
Dynamics. — That branch of mechanics which treats of
the action of forces producing motion in bodies.
Dynamo. — A dynamo electric machine. A generator.
74 ELECTRICAL DICTIONARY
Dynamo Brush-Holder. — Contrivances for holding the
collecting brushes of dynamo electric machines.
Dynamo-Electric Machine. — A machine which, by
means of electro-dynamic induction, converts me-
chanical energy into electric energy. A dynamo.
Dynamo or Motor Frame. — The iron frame of a dynamo
or motor with the standards and pole pieces in-
cluded, but not the bearings and base plates.
Dynamo Regulator. — A term applied to a style of rheo-
stat used in regulating a dynamo.
Dynamo Resistance Box. — A style of rheostat used for
regulating a dynamo.
Dynamo Terminals. — A dynamo 's main terminals.
Dynamometer. — An instrument for measuring force or
power.
Dyne. — The C. G. S. unit of force. The force capable
of imparting in one second a velocity of one centi-
meter per second to a mass of one gramme.
E. H. P. — An abbreviation of Electrical horse power.
E. M. F. — An abbreviation of Electro-motive force.
Ear Piece. — A round opening into an air chamber super-
posing the diaphragm of a telephone receiver and
so shaped as to conveniently fit the ear.
Earth. — A defect in any line of electric conduction re-
sulting from accidental contact of such line with
the earth or ground. That earth or ground which
forms part of an electric circuit.
ELECTRICAL DICTIONARY 75
Earth Circuit. — A circuit, the course of which, is formed
partly by the earth or ground. A part of the
ground or earth with which an electric circuit has
been established.
Earth Connection. — A connection which is formed by
a conductor connected to any circuit or apparatus
and the ground.
Earthenware Conduit. — A glazed earthenware conduit
usually containing many ducts.
Earth-Grounded Wire. — A wire having one of its ter-
minals placed in the ground, the earth thereby
forming a part of the circuit.
Earth Plates. — Metallic plates sunk in the ground or in
water to which the terminals of earth wires are
connected.
Earth Return. — A section of a grounded circuit the con-
ducting course of which is formed by the earth.
Ebonite. — A material composed of india-rubber and sul-
phur, very hard, highly insulating and possessing
specific inductive properties to a high degree.
Economic Coefficient. — The relation between the total
delivery of a dynamo and the total electric power
actually converted in the machine.
Economic Coefficient of Dynamo-Electric Machine.—
The relation of the electric force which a dynamo
produces at its terminals to the mechanical power
employed to drive it.
Eddy Currents. — Useless currents in the armature, pole
pieces and magnetic cores of dynamos or other
masses of metal, created by the varying strength
of contiguous electric currents, or by their motion
through magnetic flux.
, 76 ELECTRICAL DICTIONARY
Edison Distributing-Box. — A box used in the three wire
Edison distribution system.
Edison-Lalande Cell. — A zinc-copper couple having a
depolarized coating of copper-oxide on the copper,
the couple being immersed in an electrolyte of pot-
ash or caustic soda.
Effective Starting-Current of Motor.— The value of the
initial current of a motor indicated by an ammeter.
Efficiency.— The relation of a result effected to the ex-
penditure necessary to effect the result.
Efficiency of Conversion of Dynamo. — The whole sum
of electric energy produced by a dynamo divided
by the sum total of the mechanical energy nec-
essary to drive it.
Efficiency of Electric Lamp.— The relation of the lumi-
nous energy given out by an incandescent lamp to
the energy which it absorbs. The relation of the
number of candles to be had from an electric
lamp to its electric activity indicated in watts.
Efficiency of Electric Motor. — The relation of the elec-
tric power discharged at a 'motor pulley to that
which is furnished at its terminals.
Efficiency of Transformer or Converter. — The relation
of the electric power furnished at a transformer's
secondary terminals to that furnished at its pri-
mary terminals.
Efflorescence. — A change of crystalline salts to a powder
from gradual decomposition upon exposure to air,
due to loss of the crystallization water.
Elasticity. — A property inherent in bodies by which
they recover their former figure or dimensions upon
the removal of external pressure or stress.
ELECTRICAL DICTIONARY 77
Electric. — Pertaining to electricity.
Electrically. — By means of electricity.
Electrician. — A person versed in the science and appli-
cation of electricity.
Electricity. — A term applied to that unknown power in
nature which produces electric phenomena.
Electro-Bath. — The liquid solution used in electro-
plating.
Electro-Brassing. — Depositing brass upon a surface by
electrolysis or electro-plating.
Electro-Capillary Phenomena. — An electric appearance
noticeable in capillary tubes where the surfaces of
two liquids come in contact.
Electro-Chemical. — Pertaining to electro-chemistry.
Electro-Chemical Decomposition. — Electrolysis or de-
composition by means of electricity.
Electro-Chemist. — A person well versed in the science
of electro-chemistry.
Electro-Chemistry. — The department of electric science
which treats of combinations and decompositions
produced by the electric current.
Electro-Coppering-. — Coating a surface with copper by
the electro-plating process.
Electro-Deposit. — A layer of metal deposited upon an
article by electro-plating.
Electro-Deposition. — The act of coating with metal by
electrolysis.
Electro-Dynamic Machinery. — Any machinery serving
to produce, transmit, measure or use energy by
means of electricity.
78 ELECTRICAL DICTIONARY
Electro-Dynamic Motor. — An electric motor or one ope-
rated by means of electro-dynamic force.
Electro-Dynamic Rotation. — Rotation produced by
electro-dynamic force.
Electro-Dynamics. — The branch of electric science treat-
ing of the action upon one another of electric cur-
rents, or their action upon themselves or upon
magnets.
Electro-Etching. — A term applied to engraving by elec-
tricity.
Electro-Extraction of Ores. — Divers processes by which
metals are electrically extracted from ores.
Electro-Kinetic Energy. — Electrical energy in actual
performance of work.
Electro-Kinetics. — A term given to the appearances of
electricity in motion or currents of electricity; in
contrast to electrostatics or of the appearances of
electric charges or electricity in repose.
Electro-Magnet. — A magnet obtained by the flow of an
electric current through an insulated wire circuit.
A coil possessing magnetizing power encompassing
a soft iron core which is susceptible to instant mag-
netization or demagnetization when the circuit is
opened or closed.
Electro-Magnetic Ammeter. — A style of ammeter whose
needle is moved in oppostion to the field of an
electro-magnet by the field of the current it is
measuring.
Electro-Magnetic Attraction. — The reciprocal attraction
of the unlike poles of electro-magnets.
Electro-Magnetic Bell. — A bell set in motion electro-
magnetically.
ELECTRICAL DICTIONARY 79
Electro-Magnetic Brake. — A car-wheel brake either de-
riving its power from electro-magnetism, or which
is operated by electro-magnetic contrivances.
Electro-Magnetic Cut-Out. — A cut-out which acts by the
use of an electro-magnet.
Electro-Magnetic Field. — That field which either an
electric current or an electro-magnet produces.
Electro-Magnetic Flux. — Magnetic flux created by ?t»
electric current or electro-magnetism.
Electro-Magnetic Helix. — An electro-magnetic solenoid
Electro-Magnetic Induction. — A kind of electro-dy-
namic induction wherein by the motion, either of
electro-magnets or electro-magnetic solenoids, elec-
tric currents are obtained.
Electro-Magnetic Inertia. — A term applied to the self-
inductance of a current.
Electro-Magnetic Rotation. — Rotation resulting from
electro-magnetic attractions and repulsions, as in
a motor.
Electro-Magnetic Separator. — A contrivance by which
the dross is separated from the ore of finely pow-
dered low-grade iron ores. A contrivance provid-
ing for the elimination of particles of iron from
non-magnetic filings by magnetic attraction.
Electro-Magnetic Solenoid. — A coil of wire, cylindrical
in form, each of its convolutions being circular.
An electro-magnetic helix.
Electro-Magnetic Temperature-Regulator. — An instru-
ment for registering temperature electro-magneti-
cally. A regulator of temperature whose perform-
ance is contingent upon the operation of an electro-
magnet, whose action is excited by the expansion
or contraction of a solid or fluid.
80 ELECTRICAL DICTIONARY
Electro-Magnetism. — Magnetism created by electric
currents.
Electro-Mechanical Bell. — A bell moved to action by the
force exerted upon its striking mechanism by an
electro-magnet.
Electro-Mechanical Gong. — A gong whose operation de-
pends upon the action, at times, of an electric
current upon its striking mechanism ; the blow be-
ing struck by mechanical force.
Electro-Metallurgical Galvanization. — A process for de-
positing a light metallic coating by electrolytic
deposition upon the surface of any conductor, such
as, for instance : the carbon electrodes employed in
arc lamps.
Electro-Metallurgy. — The department of electric science
which pertains to the reduction or treatment of
metals by electricity.
Electro-Percussion Drill. — A drill used in mining or
excavating rock and which operates with a recip-
rocal motion produced by the flow of an alternating
electric current through one or the other of two
solenoids, of which the drill stock is the core.
Electro-Photometer. — An instrument which measures
the intensity of light by the application of elec-
tricity.
Electro-Plating. — A process for coating conducting sur-
faces with a metallic deposit by means of an elec-
tric current.
Electro-Plating Bath. — A tank holding a metallic solu-
tion into which articles to be electro-plated are
immersed.
Electro-Pyrometer. — An apparatus used to ascertain
the degrees of temperature by measuring the re-
ELECTRICAL DICTIONARY Bl
•sistance of a platinum wire which has been sub-
jected to the action of the temperature to be
determined.
Electro-Siliceous Light. — A brilliant incandescence ob-
tained in a glass tube by the discharge through it
of a powerful static machine; the tube being
crossed by a platinum wire and immersed in salt
water, resulting in the melting and volatilization of
the wire by the intense heat of the discharge.
Electro- Smelting. — The separation of metals from the
ores by means of electrically generated heat, i. e. :
heat generated by electric currents.
Electro-Therapeutics. — The use of electricity in the
treatment of the human body for disease.
Electro-Thermic. — Pertaining to the application of
electricity for generating heat.
Electro-Tinning. — The electro-plating or coating of a
substance with tin.
Electro-Type. — The electrolytic deposition of metals in
a mould in order to obtain a fac-simile.
Electro-Type. — The impression of type produced by the
electro-metallurgic process.
Electro-Type Process. — The process by which an im-
pression or cast of type is produced by means of
electro-metallurgy.
Electrocution. — Execution of the death penalty by
means of an electric shock.
Electrode. — The one or the other of electric source ter-
minals which is put into a solution where electro-
lysis is going on. One or the other of the electro-
therapeutic terminals of an electric source.
82 ELECTRICAL DICTIONARY
Electrolier. — A fixture serving to hold electric lamps as
distinguished from one designed for gas burners.
Electrolier Cut-Out. — A cut-out employed in the circuit
of an electrolier.
Electrolier Switch. — A switch serving to light and ex-
tinguish lamps in an electrolier.
Electrolysis. — The process of chemical decomposition
by the action of an electric current. The dissolu-
tion of the molecule of an electrically decomposa-
ble compound into its radicals.
Electrolyte. — A compound decomposable or subjected
to decomposition by an electric current.
Electrolytic Assaying. — Assaying by aid of electrolysis.
Electrolytic Corrosion. — The corrosion of metallic pipes
or other metallic material buried in the ground
resulting from electrolytic action.
Electrolytic Decomposition. — The dividing of a mole-
cule into its component ions or radicals by means
of an electric current.
Electrolyze. — To electrically separate or decompose.
Electrometer Fatigue. — The elastic exhaustion of an
electrometer's needle suspension resulting in its
failure to return to the zero point.
Electromotive Force. — The cause which produces cur-
rents of electricity. Potential difference causing
a current to flow.
Electromotograph. — An apparatus having a rotating
cylinder of chalk moistened with a solution of
caustic soda and a diaphragm with an arm pointed
with platinum, connected to its center and pressed
against the surface of the cylinder by a spring,
ELECTRICAL DICTIONARY 83
the point being reduced by electrolytic action in-
cident to the flow of the electric current.
Electromotographic Telephone. — A telephone for loud
speaking and operated on the electromotographic
principle.
Electron. — A word signifying amber, not obsolete, but
seldom used. An alloy of gold and silver. The
throwing of electric particles from the cathode of
a high vacuum tube.
Electropoion Liquid. — A depolarizing solution consist-
ing of one part of bichromate of potash dissolved
in ten parts of water, with two parts of sulphuric
acid added gradually.
Electroscope. — An apparatus for indicating the pres-
ence of an electric charge, and for determining its
character, as to the positive or negative state of
the charge, without measuring its amount of value.
Electrostatic Discharge. — A term used to express a dis-
ruptive discharge.
Electrostatic Generator. — A term used in general ap-
plication to divers forms of influence machines.
Electrostatic Induction-Machine. — A machine from the
initial charge of which proceeds a charge greatly
increased by its inductive action on a plate of glass
or other dielectric, rapidly rotated.
Electrum. — An alloy of gold and silver and other sub-
stances of an amber color used by the ancients and
which were susceptible to electrification by friction.
Element. — One of the ultimate, indecomposable con-
stituents of any kind of matter.
Element of Storage Battery. — One set only of positive
and negative plates of a storage cell connected in
84 ELECTRICAL DICTIONARY
such manner as to be prepared to be put into the
containing jar of acid liquid.
Elevator Annunciator. — An annunciator in an elevator
connected with the different floors from which sig-
nals are received.
Elevator, Electric. — An elevator whose motive power
is derived from electricity.
Elevator Switch. — A switch located in an elevator and
serving to control the working of the elevator
motor.
Elliptical Rotary-Magnetization. — The magnetization
manifested in a diphase motor where two alternat-
ing magnetic currents exist at the same time, each
one out of phase with the other.
Emergency Brake. — A brake adjusted to any vehicle to
be used in an emergency only. A brake used in
electrical vehicles in cases of emergency only ; pos-
sessing more than ordinary power and serving as
a reversing switch to immediately reverse the ro-
tating direction of the motor.
Emergency Crew. — A gang of men attached to a power
distribution system and assigned to emergency
duty, consisting- of prompt attention and restora-
tion in cases of break down or other irregularities.
Emergency Switch. — An auxiliary switch used on a car
controller to reverse the motion of a car when re-
quired.
Emmetropic Eye. — The human eye in its normal condi-
tion.
Enamelled Rheostat. — A rheostat the wire coils of
which are deposited in a quantity of enamel.
ELECTRICAL DICTIONARY 85
Enclosed Arc-Lamp. — A lamp with a closely fitting
globe which encloses the carbon so as to secure
around the arc an atmosphere with practically no
oxygen, by reason of which the rate of consump-
tion of the carbon is decreased.
Enclosure of Magnetic Flux. — Enclosing magnetic flux
in a ferric magnetic circuit. The linkage of the
flux.
Endlessness. — The state of a closed ring and of uniform
cross section, magnetizing coils being uniformly
wound around it, thereby securing throughout the
length of the ring a practically uniform magnetic
field.
Endosmose. — The unequal blending of two different
fluids in the penetration of any intervening porous
structure.
Endosmose, Electric. — The uneqaal blending of two
liquids through the pores of a partition, separating
cells; where an electric current is made to pass
through the partition or septum.
Energy. — Power efficiently and forcibly exerted.
Energy Efficiency of Storage Battery.— The Watt-hour
efficiency.
Energy, Electric. — Power efficiently exerted by elec-
tricity in the performance of work.
Energy Meter. — A name given to a Watt-meter.
Energy of Motion. — A term applied to kinetic energy.
Engine-Room Tachometer. — A tachometer designed for
use in connection with engines, dynamos and ro-
tating machinery generally in engine rooms.
English Heat Unit.— The British unit of heat. The heat
required to raise one pound of water 1 degree F.
86 ELECTRICAL DICTIONARY
Entrefer. — The opening of non-magnetic substance
through which the field flux must pass in a dyna-
mo-electric machine's surface, formed of air or
composed of an air gap. The breadth of the non-
magnetic gap in distinction from a smooth-cored
armature's simple air gap.
Equalizer. — A term applied to an equalizer wire. A
device by use of which electric pressure over a
system is equalized. An equalizing bar.
Equalizer Wire. — An equalizing bar. A wire by which
the series windings of several compound-wound
generators are operated in parallel.
Equalizing Bar. — A bar uniting the series coils of two
compound-wound generators connected in parallel,
thus providing that a surplus of current furnished
by the armature of one machine will of necessity
excite the other machine to a like degree.
Equator of Magnet. — A point nearly half way between
the poles of a straight bar magnet or approximately
half way from the poles of a horseshoe magnet if
measured from each pole along the bar. The
neutral point line on a magnet.
Equilibrium. — A state of rest produced by the mutual
counter-action of two or more forces.
Equipotential. — Pertaining to an equality of potential.
Equipotential Magnetic-Surfaces. — Surfaces which sur-
round the poles of a system of magnets or one
magnet at which the magnetic potential is the same.
Equivalent Air-Gap. — An air gap which would possess
magnetic resistance equal to that of a joint, sup-
posing the penetrability of the metal not to be af-
fected by cutting.
ELECTRICAL DICTIONARY 87
Erg, — The absolute C. G. S. unit of work or energy.
The work done or energy expended in moving a
body through one centimeter or against a resistance
of one dyne in one second.
Erg-Meter. — An instrument for measuring in ergs the
performance of an electric current.
Ether. — A hypothesis of a highly attenuated electric
fluid in universal space, the transverse vibrations
of which transmit light, electro-magnetic and heat
radiation.
Ether Flow Vortices. — Hypothetical vortices in ether,
whose supposed existence furnishes a basis upon
which magnetic phenomena are explained.
Evaporation. — The act or process of solids or fluids
turning into or passing off in vapor.
Evaporation, Electric. — The superficial sublimation or
evaporation of a substance under the influence of
negative electricity.
Excitation. — The generation of electricity or production
of magnetism by any method. The energizing of
an electro or magneto-receptive contrivance.
Exciter Dynamo. — One dynamo employed for the ex-
citation of another.
Exciter of Field. — A generator used for exciting the
field magnet of a dynamo.
Exhaust Fan, Electric. — An exhaust fan operated by
electricity.
Exhaust Wheel, Electric. — An exhaust wheel operated
by electricity and serving to exhaust the air from
an apartment.
Exhausted Storage Cell. — A storage cell which has been
emptied.
88 ELECTRICAL DICTIONARY
Expansion. — The act of expanding or spreading out.
The act of increasing in volume, length or surface.
Expansion, Electric. — The increase in volume of a con-
denser when charged electrostatically.
Expansion Joint. — A joint adaptable to pipes or tubes
which are exposed to changes of temperature and
which is equipped with a sliding joint to provide
for expansion and contraction.
Expended Energy. — The energy consumed in obtaining
a result.
Extension Call-Bell. — A bell connected with a telephone
call bell and located in another part of a building
and serving to summon a subscriber to the tele-
phone from a remote part of the building.
Extension Push Button. — A push button located at a
distance from the main push button.
External Armature Generator. — A generator whose
armature is outside of the field frame.
External Magnetic Circuit. — The section of a magnetic
circuit lying outside the magnetic source. That
part of a magnetic circuit lying outside of its
core.
External Magnetic Field. — That part of a magnetic field
lying outside of a magnet's body.
Extra-High-Potential System.— A potential over 3,000
volts, in the National Electric Code.
Extraneous Field. — A leakage of magnetic field.
ELECTRICAL DICTIONARY
Factor. — One of the elements or quantities which multi-
plied together form a'product.
Factor of Safety. — The relation of the reckoned or
measured strength of a structure to the maximum
strength it will be required to exert.
Fahrenheit Thermometric Scale. — The division of the
thermometer scale into 180 equal degrees, along
the length of the tube, between the melting point
of ice and the boiling point of water.
Fall-Back Indicator. — A name given to a drop indicator.
Fall of Potential. — Potential drop.
False Zero. — A zero of an instrument used for measur-
ing, the zero being taken at the position it assumes
naturally under the influence of other forces than
those impressed in the measurement.
Fan Motor. — An electric motor used for operating a
fan.
Farad. — The practical unit of electric capacity. That
capacity possessed by a conductor which is capable
of holding one coulomb of electricity at one volt
potential.
Faraday's Cube. — A room insulated and lined with tin-
foil which makes no electrical indications on the
most delicate instruments on the inside of the room
when the room has been charged on the outside.
Faradic Adapter. — A contrivance by means of which
ordinary incandescent light circuits can be used
in electro-therapeutics, with an induction coil.
Faradic Coil. — A name given to a medical induction coil
or faradic machine.
90 ELECTRICAL DICTIONARY
Faradic Current. — A term employed in medical elec-
tricity for the induced or secondary alternating
current produced by comparatively high electro-
motive force.
Faradic Machine. — A machine serving to produce fara-
dic currents.
Fathom. — A measure of length containing six feet.
Fault. — A defect in the efficient operation of a circuit
caused by ground and cross contacts or disconnec-
tions.
Fault Resistance. — That resistance which is due to a
fault.
Feed. — To furnish an electric current. To regulate the
carbon electrodes in arc lamps.
Feeder. — A conducting wire through which the current
flows for distribution to the main conductors, thus
differing from a conductor which serves to supply
translating devices directly.
Feeder Ammeter. — An ammeter located in the circuit
of a feeder generally at a switchboard.
Feeder Block. — A block having a feeder cut-out.
Feeder Box. — A box used for distribution and into
which a feeder has been run to receive the dis-
tributing connections.
Feeder-Mechanism for Arc-Lamp. — The mechanism
used to feed an arc lamp.
Feeders. — Wires which furnish the main conductors
with currents at different points whereby their
potential under load is equalized, hence differing
from wires which furnish the currents directly.
Feeding Device or Mechanism for Electric Arc-Lamps.
— A contrivance which keeps the carbon electrodes
ELECTRICAL DICTIONARY 91
of an arc lamp 'separated by a regular distance
during the time they are being consumed.
Fender. — A form of pilot employed on the front of
street cars to guard against accidental injury to
persons crossing in front of a moving car.
Ferric Inductance Coil. — An inductance coil having an
iron core.
Ferric Magnetic Circuit. — A magnetic circuit consist-
ing of iron entirely.
Ferro-Magnetism. — Magnetism which iron and other
paramagnetic substances possess.
Ferro-Manganese Alloys. — Divers alloys used for the
wires of resistance coils, the electric resistance of
which is not noticably influenced by changes of
temperature.
Field. — A term signifying a magnetic and an electro-
static field.
Field Coils. — The field-magnet coils of a motor or
dynamo-electric machine.
Field Frequency. — The frequency of rotation in a re-
volving magnetic field.
Field Magnetic Coils. — Magnetizing coils on the field
magnets of a motor or dynamo.
Field Magnets. — Magnets, generally electro-magnets,,
used to produce the field in a dynamo or motor.
Field-Regulating Box. — A resistance box.
Field Rheostat. — A field regulating box.
Field Strength. — The intensity of the magnetic force of
a field.
Filament. — A fine thread or fiber.
Filament of Incandescent Lamp. — The conductor of an
incandescent lamp which becomes incandescent.
92 ELECTRICAL DICTIONARY
Film. — A term used to describe a thin layer or deposit
obtained by electro-plating.
Filtration. — The elimination of undissolved solids from
the liquid in which they are mechanically sus-
pended.
Fire-Alarm Annunciator. — An annunciator employed in
fire alarm systems.
Fire-Alarm Signal Box. — A signal box located in the
street or other convenient place from which alarms
of fire are sent.
Fire-Alarm Telegraph. — A term applied to the whole
apparatus used in fire-alarm telegraphy.
Fish Plate. — The plates used with bolts to connect the
track rails on railroads.
Fished Wires. — Wires which have been put into ducts
by means of the fishing process.
Flashing Box. — A term at times applied to a junction
box.
Fishing Wires. — The process by which a wire is drawn
into its place through the walls, ceiling or floors of
a building and which is accomplished by inserting
the wire into a hole at one point and hooking it
from another and then drawing it through.
Fiske's Electric Range Finder. — A device employed to
obtain the distance of an object from the point of
observation, and signally useful in locating the
exact distances of targets or an enemy's ship at sea.
Five-Wire System. — A system resembling the three-
wire system in its construction, wherein four
series connected dynamos are connected to five con-
ductors.
Fixed Resistance. — A resistance having a nearly con~
ELECTRICAL DICTIONARY 93
stant value, thus differing from a regulable resist-
ance.
Fixture Electric. — Fixtures for electric lights. A fix-
ture for the accommodation of one or more incan-
descent lamps firmly attached to wall or ceiling.
Fixture Wire. — A style of insulated wire used in
electric fixtures.
Flag Signaling. — A system of semaphore signaling con-
sisting of the waving of a light flag upon the
Morse alphabetical system, the dots being repre-
sented by movements of the flag to the right and
the dashes by movements to the left.
Flaming of Carbon Arc. — An irregularity in the burn-
ing of a voltaic arc which manifests itself when the
carbons are too far from each other and the
strength of current is greater than the normal.
Flashed Carbon Filaments. — Carbon filaments which
have been improved by means of the flashing pro-
cess.
Flashing of Dynamo-Electric Machine. — A name for the
phenomena of long flashes and sparks at the com-
mutator of a dynamo resulting from the short
circuiting of the external circuit at commutator.
Flashing Process for Carbon Filaments. — A process of
treatment for the filaments of incandescent lamps
whereby improvement is made by the deposit of
carbon in the pores and over the surfaces of the
filaments, which is accomplished by subjecting the
filaments to an incandescence, while surrounded by
a carbonaceous fluid.
Flat Commutator-Segment. — A commutator segment
whose surface has become flat from burning or
wearing away.
94 ELECTRICAL DICTIONARY
Flat-Iron, Electric. — A flat-iron heated by electricity.
Flexible. — Capable of easily bending.
Flexible Cable. — A cable which can be easily bent or
flexed.
Flexible Conduit System. — A system of conduits so
devised that the conductors which the conduits are
to contain can be introduced at any time after com-
pletion.
Flexible Electric-Light Pendant. — -An incandescent
lamp pendant composed of a pair of conductors
insulated from each other and flexible.
Flexible Lamp-Cord. — A flexible cord serving to hold
an. incandescent lamp. A flexible cord having a
connection with an incandescent lamp, to some
extent portable.
Flow. — The volume of a current or stream of any fluid
escaping from an opening in a given time. The
volume of fluid passing by a certain point in a
given time.
Flow of Energy. — The passage ,of energy through the
medium by which a conductor is surrounded and
now accepted as the cause of the electrical current,
which was formerly supposed to flow through the
conductor.
Flow of Magnetic Flux. — The amount of magnetic flux
which flows through a magnetic circuit under a
certain magneto-motive force in opposition to a
certain magnetic reluctance.
Fluctuating Electromotive Force or Current. — An
electromotive force which periodically undergoes
variations of magnitude.
Fluidity. — Having fluid properties.
ELECTRICAL DICTIONARY 95
Fluorescence. — That property by virtue of which cer-
tain solids and fluids become luminous under the
influence of radiant energy.
Fluorescent Screen. — A screen bearing fluorescent
materials on its surface.
Fluoroscopic Examination. — An examination of a body
by means of an X-ray and a fluorescent screen.
Fluoroscopic Screen. — A screen overspread with fluo-
rescent material and employed for fluoroscopic ex-
amination in connection with X-rays.
Flush Box. — An iron box, covered with a heavy hand
plate and laid flush or even with the surface and
employed in systems of conduits, to make con-
nections therewith and to examine the leakage of
conductors, or for like purposes.
Flush Key-Switch. — A key switch which is flush or
even with the wall in which it is located.
Flush Switch. — A switch imbedded in the wall in such
manner as to leave its outer surface even or flush
with the surface of the wall.
Flux. — Magnetic induction; the number of lines of
force which pass through a magnetic circuit.
Flux Density. — The intensity of magnetization ex-
pressed in lines of force per unit of area of cross-
section in a plane at right angles to the lines of
force.
Focal Length. — The distance between a focus and lens.
The distance from the optical center of a lens
where parallel rays come to a focus.
Focus. — A point in which the rays of light meet after
being reflected or refracted ; as the focus of a lens
or mirror.
96 ELECTRICAL DICTIONARY
Focusing. — Modifying the distance between an object
and a lens or mirror for the purpose of producing
a clean-cut image of the object.
Focusing Arc-Lamp. — An arc lamp used with a reflec-
tor or lens and so constructed that its mechanism
feeds both carbons in such a manner as to keep
the arc at the focus of the reflector.
Foot-Pound. — A unit of work. The work necessary
to raise a pound vertically the distance of a foot.
Foot-Pound-Per-Second. — A rate of performance equal
to one foot pound expended per second.
Force. — Any action between two bodies which changes
or tends to change their relative conditions as to
rest or motion.
Force Pump. — A pump having a solid piston and serv-
ing to raise liquids vertically to a greater height
than they could be raised by atmospheric pressure.
Fork for Trolley Wheel. — A device by means of which
the trolley wheel and pole are connected.
Formed Armature- Windings. — Coils of an armature
that are wound first on a form and then placed on
the armature core.
Formers. — The forms used in producing formed arma-
tures and like windings.
Forming Storage-Battery Plates. — Causing heavy de-
posits of peroxide of lead and spongy lead re-
spectively on the lead plates of a storage battery,
by passing a charging current between them alter-
nately in opposite directions while they are im-
mersed in dilute sulphuric acid.
Formulae. — A rule or principle expressed in algebraic
language.
ELECTRICAL DICTIONARY 97
Forward Lead of Dynamo Brushes. — The displacement
of the brushes on a dynamo's commutator in the
direction in which the armature rotates.
Foucault Currents. — A term expressive of eddy cui*
rents, particularly when in armature cores. Use-
less currents created in a conducting mass by the
movement through magnetic flux.
Fountain, Electric. — A fountain worked by electric
motors and equipped with a number of jets which
when electrically illuminated display lights of dif»
ferent colors.
Fountain Projector. — An arc light projector by means
of which the jets of an electric fountain are
illuminated.
Four-Point Switch. — A switch capable of having its
circuit completed through four points, either one
at a time or simultaneously. A four-pole switch.
Four-Pole Dynamo-Electric Machine. — A dynamo-elec-
tric machine the magnet field of which is produced
by four magnet poles.
Four-Speed Regulator. — A regulator having a motor
capable of giving four different speeds.
Four-Wire System. — A system resembling in its gen-
eral order of form the three-wire system, which
provides for the connection of three dynamos to
four wires or conductors.
Fractional Distillation. — The evaporation of liquids
by heat, providing for the separation of two or
more liquids by first obtaining the degree of heat
at which the most volatile liquid will boil, and
when it has been evaporated the degree of temper-
•ature is raised sufficiently to evaporate the next
98 ELECTRICAL DICTIONARY
most volatile liquid, and so on in order until all
are evaporated. The separation of liquids by dis-
tillation in their successive order of increased tem-
perature required for volatilization.
Fractional Electrolysis. — The electrolysis of various
substances by successively raising the E. M. F.
Franklinic Currents. — Currents created by a frictional
induction machine.
Free Ether. — A name given to the ether which fills
inter-planetary space in distinction from the inter-
atomic or inter-molecular ether.
Free Vibrations. — Vibrations in a body susceptible of
elastic vibration produced by the vibration of a
neighboring vibrating body.
Freezing. — To become congealed by cold; to become
changed from a liquid to a solid state by the ab-
straction of heat.
Freezing Mixtures. — Mixtures composed of such mater-
ials as salt and ice, which melt rapidly when
mixed, thereby absorbing the heat from surround-
ing or contiguous substances. '
Freezing Point. — The point at which liquids congeal.
Frequencjr of Alternation. — The periodicity. The num-
ber of cycles accomplished in a unit of time by an
alternating current.
Friable. — Readily reduced to powder, pulverized or
crumbled.
Friction. — The effect of rubbing. The resistance which
a moving body meets with by the contact of an-
other body.
Friction Brake. — A form of brake which accomplishes
the result by friction.
ELECTRICAL DICTIONARY 99
Frictional Torque. — The torque in a motor which is
required to be exerted on the armature in order
to neutralize the friction. Torque produced by
friction.
Frog. — A triangular crossing support and guide for the
wheels of a car where one track branches off from
another or crosses it at an angle greater or less
than a right angle, and which permits a car or
train to leave one track and enter upon another.
Frying of Arc. — A hissing noise resembling the sound
of frying noticeable in voltaic arcs when carbons
are too close together.
Full Load. — A complete load. The greatest load which
a machine is intended to permanently carry.
Full-Load Efficiency of Motor. — A motor's efficiency
when working under full load.
Full-Loud Efficiency of Transformer. — A transformer's
efficiency or the relation of the power rendered at
secondary terminals to that which is taken in at
primary terminals, when working under full load.
Fulminate. — A term applied to explosives of high ex-
plosive properties.
Fundamental Units. — Units of dimension, mass and
time to which all quantities >are referred, and
which are distinct from derived units.
Furnace, Electric. — A furnace in which the heat, elec-
trically generated, is used to produce difficult
fusions whereby metals are separated from the
ores, and also for the prosecution of other metal-
lurgical operations.
Fuse Block. — A block having a safety fuse.
Fuse Board. — A board made of an incombustible
100 ELECTRICAL DICTIONARY
material, usually slate, upon which a number of
safety fuses are mounted.
Fuse Box. — An incombustible box containing a safety
fuse or fuse wires.
Fuse Links. — Links composed of strips or plates of
fusible metal, serving as safety fuses.
Fuse Panel. — A panel in a switchboard designed to sup-
port the safety fuses.
Fusible Plug. — A name sometimes used for a safety
plug.
Fusing Current. — A term signifying the quantity of
current which causes the blowing or melting of a
fuse.
Galvanic Adapter. — An apparatus by means of which
feeble continuous currents are obtained from an
electric light circuit for use usually in electro-
therapeutic treatment.
Galvanic Battery. — A term, now misapplied, but some-
times used to signify a voltaic battery.
Galvanic Electricity. — A term, now misapplied, but
sometimes used to signify voltaic electricity.
Galvanic Multiplier. — A term practically obsolete, once
applied to a galvano-meter.
Galvanic Taste. — A taste resulting from the passage
through the tongue of a voltaic current.
Galvanized. — Subjected to galvanic action. The coat-
ing of a metal with zinc by cleaning and immers-
ing in melted zinc.
ELECTRICAL DICTIONARY , , , , 101
Galvanized Iron. — Iron covered' with a coating of zinc.
Galvanized Iron Wire. — An iron wire zinc coated.
Galvanizing. — Coating iron with a layer of zinc by im-
mersion in the melted metal. ' Subjecting the
nerves or muscles of the human body to galvanic
influences.
Galvanometer. — An instrument for measuring electric
current strength by the deflection of an electric
needle.
Galvano-Plastic Matrix. — A mould serving for the
reception of a galvano-plastic deposit.
Galvano-Plastics. — A term applied to electrotyping, or
the process by which is obtained electrolytic
deposits of such sufficient body upon any suitable
object as to permit of its convenient separation
therefrom.
Galvanoscope. — A crude instrument of the galvanome-
ter type, employed for ascertaining whether or not
a current is flowing.
Gap Wire Gauge. — A style of gauge for measuring
wires, having a metallic plate that contains gaps
or sets of gaps which may be bridged or filled by
the wire to be measured.
Gas Engine. — An engine deriving its motive power
from heat generated by burning or exploding gas.
Gas-Jet Photometer. — A photometer in which a burning
gas jet represents the standard of light and which
burns with or without a diaphragm at a definite
height and under standard conditions of pressure
and volume.
Gas-Lighting, Electric. — The. ignition of a gas jet from
a distance by electricity.
102 ELECTRICAL DICTIONARY
Gassing. — The development of gas from secondary or
storage battery plates.
Gauze Brushes for Dynamo or Motor. — Collecting or
commutator brushes for a dynamo composed of
wire gauze compressed into suitable shape.
Gearless Car Motor. — A motor the speed capacity of
which allows it to be directly connected on the car
wheel axle without interjacent gearing.
Geissler Mercurial Pump. — A mercurial air pump which
exhausts by the Torricellian vacuum principle.
Geissler Tubes. — Sealed tubes of glass containing
highly rarefied gases, either with or without fluo-
rescent liquids or solids or both, and provided with
platinum electrodes passing through and fused into
the glass, luminous effects being produced on the
passage of the electric discharges.
Generator. — A dynamo-electric machine.
Generator Ammeter. — An ammeter designed to measure
the total current sent out by a generator.
Generator Bus-Bars. — The copper 'conductors used in
electric lighting or power stations to receive the
current from all the dynamos.
Generator Panels of Switchboard. — The panels of a
central station switchboard upon which the gen-
erator bus-bars are mounted and which maintain
the switches, generator ammeters and volt-meters.
Generator Switch. — A switch serving to connect or dis-
connect a generator from the bus-bars.
Generator Voltmeter. — A voltmeter serving to measure
the pressure of the generator with whose circuit
it is connected.
ELECTRICAL DICTIONARY 103
Geographical Equator. — The great imaginary line en-
circling the earth midway between the poles.
Geographical Meridian. — Any great imaginary line en-
circling the earth in the direction of and passing
through the poles and cutting the equator at right
angles.
German-Silver Alloy. — An alloy composed of copper
1/2, zinc 14, nickel % and used for wires of resist-
ance coils.
Girder Armature. — An armature whose core in shape
resembles a girder or H.
Glass Fuse. — A fuse confined in a tube of glass with
metallic ends.
Globe Net for Arc Lamp. — A light wire netting some-
times used on the outside of arc light globes.
Glow Lamp, Electric. — A lamp in which the light is
obtained by glow illumination. Another term ap-
plied to electric incandescent lamps.
Gold Bath. — An electrolyzable solution of gold salt used
for depositing the metal in the electro-plating pro-
cess ; a gold plate, which acts as the anode, being
immersed in the liquid opposite the article to be
plated, and which article acts as the cathode.
Gold-Leaf Electroscope. — An electroscope consisting
of two leaves of gold enclosed in a glass vessel and
hung in contact with each other from the end of a
conductor, and which diverge when excited, thus
serving to detect the presence of an electric charge,
or to determine whether it is positive or negative.
Good Earth. — Solid earth connection. Total earth con-
nection. A fault when a conductor is fully con-
nected to earth or grounded at some intermediate
point.
104 ELECTRICAL DICTIONARY
Governor, Electric. — A device serving to control the
speed of steam engines and electric motors, or to
govern the resistance of an electric circuit, the
flow of fluids into or out of their reservoirs, the
direction of a current in a plating bath, and to
perform other like functions.
Gradient. — The rate of ascent or descent by regular
degrees of inclination or quantity as referred to
some fixed point or quantity.
Gramme. — A unit of weight equivalent to the weight of
one cubic centimeter of pure water at its maximum
density at a temperature of 39.2 degrees Fahren-
heit, in a vacuum. A unit equal to 15.43235 grains
troy or avoirdupois weight.
Gramme Armature Winding. — A winding taking its
name after Gramme, who first used it on the
armature of a dynamo-electric machine.
Gramme-Calorie. — The quantity of heat which is nec-
essary to raise a gramme of water one degree cen-
tigrade.
Gramme-Ring Transformer. — A transformer the pri-
mary and secondary coils of which are placed on
closed rings.
Gramophone. — An instrument which records and repro-
duces articulate speech.
Gramophone Record. — A record of speech -secured by
means of a gramophone.
Granular-Carbon Telephone-Transmitter. — A telephone
transmitter is which carbon dust is employed.
Graphite. — A condition of carbon distinguished by its
softness and metallic luster, and serving to write
on paper and other suitable material surfaces.
ELECTRICAL DICTIONARY 105
Graphophone. — See Gramophone.
Graphophone Record. — See gramophone record.
Grappling. — Recovering a sunken cable or other object
with a grapnel.
Grapnel. — A device serving to recover a sunken cable
or other object.
Gravitation. — The attraction or force by means of
which all bodies or particles of matter in the uni-
verse tend towards each other.
Gravity. — The force which causes the tendency of
masses or particles of matter toward a center of
attraction or towards one another.
Gravity-Drop Annunciator. — An annunciator whose
signals act by the fall of a drop released electric-
ally.
Gravity-Feed Arc-Lamp. — An arc lamp whose upper
or positive carbon is held by a feeding mechanism
which drops it towards the negative carbon by the
force of gravity.
Grease-Spot Photometer. — A photometer whose disc is
a piece of paper upon whose center a spot is sat-
urated with melted paraffine. A Bunsen disc
photometer.
Ground. — A term applied to the earth when used as
a return circuit.
Ground Circuit. — A circuit in which the earth acts as
a part of the course through which the current
passes.
Ground Detector. — An instrument employed in a cen-
tral station for indicating, by the brilliancy of a
lamp, the presence of a ground in a system of
incandescent lamp distribution.
106 ELECTRICAL DICTIONARY
Ground Indicator. — An instrument which instantly in-
dicates any defect in the insulation on a line. A
detector for discovering any loss of insulation.
Ground-Return. — A term used generally signifying the
use of the ground as part of an electric circuit.
Grounded Dynamo. — A dynamo the circuit of which
has been grounded purposely or by accident.
Grounding1. — A term given in electro-metallurgy to the
preparatory operation in the process of burnishing.
The connecting of a circuit with the ground.
Gutta-Percha. — A concrete juice produced by various
tropical trees and much valued in electrical work
for its high properties of insulation and great
resistance to the destructive agencies when used
in submerged or -submarine cables.
Guy. — A rope, rod, chain or wire attached to anything
to steady and support it, as for instance : a smoke
stack, telegraph pole and similar structures.
Guy Rods. — Metallic rods serving as guys.
Guy Wire. — A wire serving as a guy.
Gyration. — The act of turning or whirling around a
fixed center.
Gyrostat. — A fly wheel whose revolving motion is gyro-
static. A fly wheel having a considerable move-
ment of mass, properly mounted upon pivots within
a case and readily transportable, for the purpose
of indicating the resistance offered by rotating
bodies to changing their plane of rotation.
Gyrostatic Action of Dynamo on Ship-Board. — The
action which takes place at the bearings of a
dynamo in operation on a rolling vessel at sea,
resulting in gyrostatic stresses.
ELECTRICAL DICTIONARY 107
H. P. — An abbreviation for horse power.
H-Armature Core. — An armature having a core resem-
bling in shape the letter H. An I-armature, girder
or shuttle.
Half-Load Efficiency. — The efficiency possessed by a
device when working under half load.
Half-Shade for Incandescent Lamp. — A reflecting shade
conforming in outline to the lamp chamber, but
covering only one-half of it.
Hand Generator. — A dynamo or a telephone magneto-
generator driven by hand.
Hand-Hole of Conduit. — A box or aperture large
enough to admit the hand and providing for access
to the cable under ground, thus readily permitting
the cable to be tapped.
Hand Regulation. — Eegulation of a dynamo accom-
plished by the hand, as distinguished from regula-
tion automatically effected, and which maintains
constant, either the current or the potential.
Hand Regulator. — A resistance box the separate coils
of which are easily set within or removed from the
circuit by hand.
Hand Telephone. — A telephone receiver used by hold-
ing it in the hand as distinguished from one
adjusted to the head.
Hanger Board. — A board serving to facilitate the
removing or replacing of an arc lamp from a cir-
cuit.
Hard-Drawn Copper Wire. — Copper wire, hardened
without annealing by being drawn several times.
108 ELECTRICAL DICTIONARY
Hard Porus Cell. — A hard-burned porus cell, which
used in a voltaic cell obtains a comparatively high
resistance; but which has greater capacity of
resistance against the disintegrating action of the
crystallizing saline substances in the battery.
Harmonic Analyzer. — An instrument which resolves
automatically a complex harmonic into its simple
harmonic components. A receiver containing a
vibrating reed acted upon by an electro-magnet and
answering only to impulses tuned to its own pitch,
and when such impulses are received from the
magnet the reed vibrates, but will not respond to
impulses not in harmonic frequency.
Harmonic Currents. — Currents which alternate period-
ically and vary harmonically. Electric currents
that are harmonic functions of time. Simple
periodic currents the strengths of which are ex-
actly represented by sinusoids.
Harmonic Frequencies. — A succession of frequencies
the values of which being integral multiples of
their fundamental.
Harmonics. — The doctrine or science of musical sounds.
The secondary or less distinct tones which accom-
pany any principal and apparently simple tone.
Harveyizing. — A process by which steel plates are su-
perficially hardened.
Haulage, Electric. — The moving of car or vessel by the
action of electricity.
Head-Board of Dynamo. — A board insulated and em-
ployed on a dynamo-electric machine to receive ter-
minals or switches.
Head-Board of Motor. — A switchboard connected with
and used to start a motor.
ELECTRICAL DICTIONARY 109
Head Guy. — A guy made fast to the top of a pole.
Head-Light, Electric. — An engine head parabolic reflec-
tor illuminated by electricity.
Head of Liquid. — The perpendicular distance from the
level of a liquid in a vessel to the center of gravity
of an orifice placed in it.
Jleat. — The force agent in nature upon which depends
the -state of bodies as solid fluid or aeriform, and
recognized in its effects by expansion, fusion, evap-
oration, etc. A form of energy.
Heat, Electric. — Heat generated by an electric current
passing through a conductor.
Heat Units. — Units founded upon the amount of heat
necessary to raise one degree of the thermometric
scale.
Hekto. — A prefix for one hundred.
Hekto-Ampere. — One hundred amperes.
Hekto- Watt Hour. — One hundred watt-hours, or a unit
of work equal thereto.
Heliograph. — An instrument for communication by
means of sunlight flashes which are made by their
manipulation to represent the Morse telegraphic al-
phabet. An instrument employed for communica-
tion between distant points and effected by inter-
cepting at intervals the beams reflected from a mir-
ror, the various durations of which correspond to
the Morse signal code.
Heliostat. — An instrument by which a sunbeam may be
introduced into a dark room from a mirror which
is mounted on an axis parallel to the earth's axis,
and by means of clock-work the beam is kept in a
fixed position despite the rotation of the earth.
110 ELECTRICAL DICTIONARY
Heliotropism. — A twisting on the growth of stalks and
stems resulting from the influence of any light
source.
Helix. — A spiral line, as of wire .in a coil. A circum-
volution.
Henry. — The practical unit of electro-magnetic or mag-
netic inductance.
Henry's Coils. — A number of induction coils separate
and connected in a manner so that the currents in-
duced in the secondary of the first coil results in
the same effect in the secondary of the second coil,
with the primary of which it forms a series con-
nection, and thus throughout the coils.
Hermetical Seal.— A seal obtained in a glass vessel by
heating its neck until it is soft and then twisting it
until the aperture is accurately closed.
High Commutator Bars. — Commutator bars which in
the natural wear of the commutator project beyond
the others and require turning down to restore
cylindrical symmetry.
High-Economy Lamp. — A lamp of high efficiency.
High Frequency. — A frequency greater than that usual-
ly employed.
High-Potential Current. — A term carelessly used to sig-
nify a current caused by high electromotive forces.
High-Potential System.— Pressure from 300 to 3,000
volts, according to the National Electric Code.
High-Potential Testing- Transformer. — An alternating
current transformer which obtains a high alternat-
ing pressure from an ordinary alternating current
circuit and employed to test insulation.
ELECTRICAL DICTIONARY 111
High-Potential Wires. — Circuit wires highly insulated
and used for connection with high potential
sources.
High Resistance. — A much higher resistance for any
circuit or apparatus than that which is usually em-
ployed.
High-Resistance Magnet. — A term applied sometimes to
a long-coil magnet of light wire and which pos-
sesses high electric resistance.
High-Speed Electric Motor. — An electric motor of the
usual design as distinguished from one built to run
at low rate of speed.
High-Tension. — A circuit used with high electric pres-
sures.
High Vacuum. — A vacuum approximately or nearly
perfect; a vacuum wherein the molecules of the
residual gas seldom come into collision with one an-
other in the containing vessel, but move to and fro
between its walls, the gas being in an ultra-gaseous
condition.
Hissing Arc. — A term applied to a voltaic arc which
produces a hissing noise due to too close approach
of the carbons.
Holder for Safety Fuse.— A support of infusable mate-
rial serving to hold a safety fuse and catch the
fused metal.
Holders for Brushes of Dynamo-Electric Machine. — The
adjustable clamps for holding the armature brushes
of dynamos and motors.
Holophane. — A globe or chamber of glass with a lenti-
form external surface employed for the better dif-
112 ELECTRICAL DICTIONARY
fusion of the light emerging from the enclosed
source.
Homopolar Dynamo. — A one-pole dynamo. A dynamo
the conductor of which moves constantly past poles
of single polarity only.
Horizontal Candle Power. — The intensity of light
emitted horizontally from a source.
Horizontal Intensity of Light. — The intensity of light
measured horizontally.
Horns of Pole-Pieces of Dynamo. — In dynamo-electric
machines the projecting ends of the pole pieces to-
wards or from which the outer uncovered perimeter
of the armature turns in its regular operations.
Horse-Power. — A unit or standard by which the capa-
bilities and rate of doing work by a prime mover
is measured ; estimated as 33,000 pounds raised one
foot in a minute.
Horse-Power, Electric. — A rate of electrical perform-
ance equal to 746 watts, or 746 volt-coulombs per
second.
Horse-Power-Hour. — A unit or standard of work equal
to that accomplished by one horse-power during
one hour.
Horseshoe Electric Magnet. — An electro-magnet the
core of which resembles a horseshoe or the letter U
in shape.
Horseshoe Magnet. — A bar of magnetized steel or hard
iron resembling a horseshoe or the letter U in
shape.
Hot-Wire Ammeter. — An ammeter the readings of
which are established by taking as a basis the ex-
pansion of a wire, obtained by an increase of tern-
ELECTRICAL DICTIONARY 113
perature resulting from the passage through it of
the current to be measured.
Hot-Wire Thermometer. — A thermometer which indi-
cates by means of the expansion of a bi-metallic
wire.
Hot-Wire Voltmeter. — A voltmeter the indications of
which are based upon the lengthening of a wire oc-
cupying a position in the circuit of the electro-
motive force to be measured.
Hydraulic Power Dynamometer. — A dynamometer serv-
ing to measure hydraulic power.
Hydraulic Storage. — The storing of energy by forcing
water into elevated reservoirs.
Hydraulics. — That branch of science or engineering
which treats of fluids in motion; the transmission
of water through conduits or pipes, and the appa-
ratus employed in raising or moving water.
Hydro-Dynamics. — That branch of the science of me-
chanics which relates to the laws of rest and motion
of fluids.
Hydrometer. — An instrument employed to determine
the amount of moisture in the atmosphere.
Hypothesis. — A proposition or principle which is as-
sumed in order to draw an inference or conclusion
in proof of the point in question. A theory as-
sumed to account for known phenomena.
Hypothetical. — Pertaining to a hypothesis.
Hypsometer. — An instrument employed to determine
altitudes by ascertaining the temperature at which
water will boil at such altitudes.
Hysteresis. — A tardiness of magnetization in respect to
magnetizing force. Molecular friction proceeding
114 ELECTRICAL DICTIONARY
from magnetic variations of stress. A quality in-
herent in a paramagnetic substance through which
energy is dissipated when its magnetization is re-
versed.
Hysteresis Losses. — Losses of useful energy resulting
from hysteresis.
Hysteretic Torque. — The part of the torque of a dyna-
mo-electric machine resulting from hysteretic influ-
ence and calling for the expenditure of mechanical
work to develop hysteretic energy, as heat in the
iron undergoing magnetic reversal.
I. H. P. — An abbreviation for indicated horse-power.
Idle Coil. — A coil through which no current is passing.
Idle Wire. — A wire through which no current is passing
* or no useful current is passing. An open-circuited
armature wire which is not generating E. M. F.
Igniter. — A strip of carbon inserted between the free
ends of a candle of the Jablochkoff type and which
upon the passage of a current through it becomes
incandescent and burns away in a short time, thus
.forming an arc producing the light.
Ignition, Electric. — The act of igniting an explosive or
any combustible substance with heat generated by
electricity.
Illuminated Dial Instrument. — An instrument used in
engine rooms or central stations, the dial of which
is translucent and illuminated from behind in order
that the indicator may be seen distinctly from a
distance.
ELECTRICAL DICTIONARY 115
Illumination. — The current of light projected on a sur-
face per unit of area from a source of light directly
or by reflection, indirectly.
Impact. — The single instantaneous blow or stroke of a
body in motion against another either in motion or
at rest.
Impedance. — The relation of any impressed electro-
motive force to the current which is produced by it
in a conductor. The sum of all factors offering re-
sistance to a current, whether spurious or ohmic —
apparent resistance.
Impedance Coils. — A name sometimes given to chok-
ing, economy or reactance coils.
Imperfect Magnetic Circuit. — A term sometimes given
to a magnetic circuit in which the intensity of the
flux is greater through some parts of the ferric cir-
cuit than through others by reason of the magnet-
izing coil being put only on one part of the core,
hence some of the lines of induction instead of com-
pleting their circuits through the core itself, do so
through the space surrounding the core.
Impressed. — Forced upon or made to act.
Impressed Electromotive Force. — The electromotive
force caused to act in a circuit to generate a cur-
rent in it. The electromotive force expended in
causing a current induction in a neighboring cir-
cuit.
Impulse. — The motion produced by the sudden or mo-
mentary action of a force upon a body.
Impulsive Current-Rush in Inductive Circuit. — An ab-
normal flow of current occasioned by the sudden
switching of a transformer on to an active main.
116 ELECTRICAL DICTIONARY
Incandescence. — The glowing whiteness of a body
caused by intense heat.
Incandescent Bombardment Lamp. — An incandescent
lamp in which the molecular bombardment result-
ing from the passage of an electric discharge
through a rarefied space raises a refractory ma-
terial to a state of incandescence.
Incandescent Circuit. — A circuit upon which incandes-
cent lamps are operated.
Incandescent-Cut-Out. — A cut-out adapted to use in an
incandescent circuit. A safety-fuse cut-out.
Incandescent Filament. — The filament employed as a
conductor in an incandescent lamp, usually of
small cross-section.
Incandescent Electric Lamp. — An electric lamp pro-
vided with a filament usually of carbon, and which
produces the light by being electrically heated to a
state of incandescence.
Incandescent Lamp-Cord. — A flexible cord inclosing
two conductors and used for%a pendant incandes-
cent lamp.
Incandescent Lamp-Socket. — A socket serving to re-
ceive and hold an incandescent lamp.
Incandescent Mantle-Burner. — A gauze mantle made of
a refractory substance and raised to a state of in-
candescence by the heat of a Bunsen flame.
Incomplete Circuit. — A broken or open circuit.
Indestructibility of Energy or Matter. — A hypothesis
which assumes that matter and energy are inde-
structible and that the disappearance of them from
certain forms is necessarily followed by their reap-
pearance in other forms.
ELECTRICAL DICTIONARY 117
India Rubber. — A substance obtained from the milky
juice of a tropical tree.
Indicating Switch. — A switch which employs an indi-
cator from which it can be ascertained whether the
circuit of the switch is open or closed.
Indicator Card. — The card from the indicator of a
steam engine from which the horse-power is reck-
oned by means of the curves of pressure which are
traced thereon.
Indicator, Electric. — A term used signifying the divers
styles of devices which are employed to indicate by
the deflection of a needle or the sounding of a bell,
at some remote point, the condition of any electric
circuit and the strength of current flowing through
it, the head of liquid pressure carried by a boiler,
the temperature, speed and general working of
machinery and the occurrences incidental thereto.
Induced. — Caused by induction.
Induced Current. — A current caused by electro-dyna-
mic induction.
Induced Current of Transformer. — A term applied to
the secondary current of a transformer.
Inducing1 Circuit. — A circuit causing induction.
Inducing Current of Transformer. — A term used for the
primary current of a transformer.
Inducing Magnet. — A relay's permanent magnet.
Inductance. — That capacity of a circuit which enables
it to exercise induction and create lines of force.
The ratio between the total induction through a
circuit to the current producing it. A property
by virtue of which the passage of an electric cur-
rent, in producing a magnetic field, is necessarily
118 ELECTRICAL DICTIONARY
accompanied by an absorption of electric energy.
A constant quantity in a circuit having no iron and
at rest and which is usually expressed in the prac-
tical units of induction or henrys.
Induction. — The influence exerted without apparent
communication by a magnetic field or a charged
mass upon neighboring bodies.
Induction Alternator. — A name used signifying a cer-
tain type of alternating generator.
Induction Coil. — A coil wherein the electro-motive force
of a portion of a circuit is by mutual induction
made to cause higher or lower electromotive force
in a neighboring circuit.
Induction Generator. — A generator which furnishes
currents that have been reinforced in its coils after
receiving them from the line by induction. An
alternating dynamo whose generative power is ob-
tained by the inductive action of the main current.
Induction Multihase-Motor. — An alternating-current
induction-motor worked by multiphase currents.
Inductor Alternator. — An alternator having both its
armature and field fixed and with a rotating frame
fixed within it, so as to generate E. M. F. in coils
on the armature.
Inductor Alternating Generator. — An alternator in
which there is no rotation of field coils or armature
coils, and having a rotating iron frame which pe-
riodically fills the armature lops with magnetic
flux and empties them.
Inductor Dynamo. — A generator with stationary field
and armature coils; the motion of inductors pass-
ing them altering the magnetic flux through them.
ELECTRICAL DICTIONARY
Inductor Generators. — Inductor alternators or dyna-
mos.
Inductors. — Laminated masses of iron in inductor
dynamos used to effect variations of magnetic flux
of armature and core.
Inertia. — That property in matter by which it tends,
when at rest to remain so.
Inflection. — The bending of rays of light or radiant en-
ergy by defraction when passing by a sharp edge.
Influence. — A term used at times signifying electro-
static induction.
Injector. — An instrument employed to introduce a con-
denser or other device into an electric circuit at a
definite moment and for a definite interval of time.
In-Put. — The power which a machine absorbs in per-
forming a certain quantity of work.
Inside Wiring. — The conductors employed in a system
of incandescent lighting to convey the current to
the interior of a building which is to be lighted.
Conductors located in the interior of a building.
Installation. — A term including all the accessories of
and the entire plant necessary for the performance
of any specified work.
Installation, Electric. — The establishment of an electric
plant.
Instantaneous. — Done in an instant.
Insulate. — To insulate a body in such manner that elec-
tricity can neither be conducted to it nor from it.
Insulated Conductors. — Conducting wires covered with
an insulating coating.
Insulating1 Joint. — A joint used for the purpose of in-
120 ELECTRICAL DICTIONARY
sulating a combination gas and electric fixture
from the gas pipe.
Insulating Tape. — An adhesive tape of flexible material
•saturated with rubber, okonite or other insulating
substances and used to effect insulation on the
stripped ends of wire or electric conductors at
joints or wherever else exposed.
Insulating Varnish. — A varnish composed of insulating
material.
Insulating Washer. — A washer made of insulating ma-
terial.
Insulation. — The application or employment of any ma-
terial or medium by which electricity, heat, light,
etc., are prevented from entering into or escaping
from the body insulated.
Insulation Break-Down. — Any defect of insulation
which prevents or interferes with perfect insula-
tion.
Insulation Resistance. — That resistance offered by an
insulated conductor's insulation, expressed in ohms
per mile and ascertained by measuring the resist-
ance between the conductor and water into which
a portion of the line has been immersed ; the length
of the immersed portion being known and having
its ends above the fluid. The resistance which ex-
ists between a conductor and the earth in a circuit
through insulating materials which lie between
them. A term used to express the resistance of in-
sulating material which covers a wire or conductor.
Any resistance offered by insulation.
Intake. — A synonymous term for "in-put."
Intake of Dynamo. — The mechanical activity taken in
by a dynamo relatively to time.
ELECTRICAL, DICTIONARY 121
Integrating Meter. — A meter which, records and reckons
a quantity relatively to time.
Integrating Wattmeter. — A meter or watt-hour-meter
which indicates the whole power that passes
through it relatively to time.
Intensity. — The amperage or strength of a current. The
strength of a magnetic field or its magnetic den-
sity as distinguished from tension in case of dynam-
ic electricity. The degree of concentrated acting
forces.
Intensity of Current. — Current strength. Current
strength or density taken per unit-area of cross-
section.
Intensity of Field. — The intensity of a magnetic field
measured at any point by the force with which
it acts on a unit magnet pole located at that point.
That intensity of field which acts on a unit pole
with a force of one dyne.
Intensity of Light. — The degree of energy exerted
with respect to candle-power.
Intensity of Magnetization. — A quantity representing
the intensity of magnetization caused in a body. A
quantity representing the intensity of magnetiza-
tion conveyed to a magnetizable body or substance.
The quantity of magnetism present or induced in
a mass and represented by the magnetic lines of
force in cross sectional area.
Inter-Connected Armature Winding. — A connection of
the separated circuits in a multipolar armature ef-
fected in such manner as to provide for the em-
ployment of a single pair of brushes on the com-
mutator. An armature cross-connected.
122 ELECTRICAL DICTIONARY
Interior Conduit. — A conduit for the accommodation of
house wires and located within the walls or in
other suitable spaces inside of a house or build-
ing.
Interior-Conduit Junction Box. — A box serving, in an
interior system of conduits for the reception of the
terminals of feeders, and as a place where feeders
and mains or mains and branches are connected.
Intermittent. — Ceasing to act at intervals. Fluctuating.
Intermittent Current. — A current flowing and ceasing
to flow at intervals, resulting in the practical pres-
ence and absence, alternately, of electricity from
a circuit.
Intermittent Earth. — An intermittent contact of a tele-
graphic or other line with the earth, causing a
fault, and which is occasioned by the action of
wind or by expansion from heat. A swinging
earth.
International Ampere. — The value of the ampere which
was defined in 1893 at Chicago by the International
Electrical Congress. One-tenth of the absolute
C. G. S. unit of current strength, or a value equal
to the one-tenth of a unit in the C. G. S. system of
electro-magnetic unity and represented with prac-
tical exactitude by the unalterable current, which,
when consonant with certain specifications while
passing through a solution of nitrate of silver in
water, deposits the metal at the rate per second of
0.001118 of a gramme.
International Ohm. — The value of the ohm which was
defined in 1893 at Chicago by the International
Electrical Congress. The practical unit of resist-
ance; 10° C. G. S. electro units. On ohmic value
ELECTRICAL DICTIONARY 123
equal to 109 units of resistance of the C. G. S. sys-
tem of electro-magnetic units and represented by
the resistance opposed to an electric current by a
column of mercury of a constant cross sectional
area, 14.4521 grammes in quantity, at the melting
temperature of ice, and a length of 106.3 centi-
metres.
International Volt. — The value of the volt defined in
1893 at Chicago by the International Electrical
Congress. An electromotive force, which, steadily
applied to a conductor whose resistance is one in-
ternational ohm, will produce a current of one in-
ternational ampere, and which is represented suf-
1 000
ficiently well for practical use by - —of the elec-
1434
tromotive force between the poles or electrodes of
the voltaic cell known as Clark's cell, at a tempera-
ture of 15 deg. C. or 59 deg. F., and prepared ac-
cording to certain specifications.
International Watt. — The value of the Watt defined in
1893 at Chicago by the International Electrical
Congress. A value which is equal to 107 units of
activity in the C. G. S. system and equal to per-
formance at the rate of one jouleper-second.
Interrupted. — Opened or broken.
Interrupter. — Any device which breaks or interrupts a
circuit.
Inter-Urban Electric Railway. — An electric railway-
running between neighboring towns or cities.
Inter-Urban Telephony. — Telephonic communication
between neighboring towns or cities.
Inverse Current. — A current produced in a conductor
when a current is started or strengthened in a
124 ELECTRICAL DICTIONARY
parallel conductor which has a parallel component.
The current produced in an induction coil when
the circuit of the primary is making or completing.
Inverted Arc-Lamp. — An arc lamp wherein the positive
carbon is below or inverted instead of uppermost,
as in the regular arc lamp.
Inverted Dynamo. — A dynamo having its armature
chamber below the field magnet coils.
Iron-Armored Conduit. — An iron-covered conduit. A
conduit wherein each duct is provided with an iron
covering or casing.
Iron-Clad. — Covered with iron.
Iron-Clad Armature. — A dynamo or motor armature the
insulating coils of which are almost or completely
surrounded by the iron of armature core.
Iron-Clad Coil. — A magnet which is iron-clad.
Iron-Clad Dynamo. — A dynamo with an iron-clad arma-
ture or encased in iron.
Iron-Clad Electro-Magnet. — An electro-magnet the mag-
netizing coil of which is almost completely sur-
rounded by iron to augment its portative power, or
its inductance, or to protect its magnetic variations,
as the case may be.
Iron-Clad Rheostat. — A rheostat with resistance coils
having an insulation incased in enamel and sunk
into a mass of iron.
Iron-Loss in Transformer. — The loss of energy sus-
tained by a transformer by reason of magnetic
hysterics or friction, and also due to the establish-
ment of eddy or Foucault currents in iron.
Iron Magnet Circuit. — A circuit signifying a ferric cir-
cuit.
ELECTRICAL. DICTIONARY 125
Isobars. — Imaginary lines connecting those places on
the earth's surface where the mean height of the
barometer at the level of the sea is the same.
Isolated Electric Lighting. — Electric lighting by a plant
situated on the premises lighted, in distinction from
one which is situated at a central station and
which supplies the current to a number of buildings
or to the service of an extended area.
Isolated Plant. — An electric plant supplying the current
for lighting a building or an assemblage of struc-
tures or buildings, in distinction from one supply-
ing the current from a central station.
Isothermal Expansion of Gas. — The expansion of a gas
while maintaining its temperature constant.
Isothermal Surfaces. — Surfaces of a body upon which
the temperature is the same at all points.
J.
Jablochkoff Candle. — An arc lamp without regulating
mechanism producing an arc between the ends of
parallel carbons which are maintained at constant
distance apart by the introduction between them
of a strip of insulating material.
Jablochkoff 's Igniter. — A small carbon conductor in
form of a strip, being easily raised to incandescence
by a current, and which is introduced between the
free ends of the parallel carbons of a Jablochkoff
candle, thus forming an arc upon the passage of
the current.
Jacobi's Law. — A law of electric motors which states
that the maximum work of a motor is performed
when its counter electro-motive force is equal to
126 ELECTRICAL DICTIONARY
one-half the electro-motive force expended on the
motor.
Jaws of Switch. — A clamp of metal used for the recep-
tion of the knife blades of a switch.
Joint. — The point where two or more conductors join.
Joint Resistance. — The united resistance offered by a
number of resistances connected in parallel.
Joule. — The practical C. G. S. unit of electric energy
which is equal to 107 ergs — 0.73734 foot pound —
.00134 horse-power seconds. The quantity of elec-
tric work necessary to raise the potential of one
coulcomb of electricity one volt. Ten million ergs.
Joule Effect. — The heating effect of a current flowing
through a conductor, produced by its resistance
only.
Joule's Law. — A law stating that the heating power of
a current is proportioned to the product of the
square of its strength and the resistance of the cir-
cuit through which it flows.
Journal. — The portion of a shaft or other revolving
piece which turns in some other piece or support.
Jumper. — A shunt or short circuit employed, for the
time being, around a source, lamp or receptive con-
trivance on a series connected circuit, in order that
it may be easily removed or repaired.
Jump Spark. — A disruptive spark excited between two
conducting surfaces in distinction from a spark ex-
cited by a rubbing contact.
Junction Box. — A box, proof against moisture, utilized
in an underground system of conductors to receive
the terminals of feeders, and wherein the feeders
are connected to the main, and through which in-
dividual consumers are supplied with currents.
ELECTRICAL DICTIONARY 127
K.
K. W. — An abbreviation for kilowatt.
Kaolin. — A variety of clay serviceable for insulating.
Keeper of Magnet. — A bar of soft iron used to connect
the poles of a magnet and designed to prevent loss
of. magnetism, the magnetic flux passing through it.
Key-Board. — A switchboard.
Key Lamp-Socket. — A lamp socket supplied with a key
attachment which is manipulated to light or extin-
guish the lamp.
Keyless. — Having no key.
Keyless Lamp-Socket. — A lamp socket not provided
with a key and which depends for its ignition or
extinction upon a switch located elsewhere.
Keyless Wall-Socket. — A socket placed on a wall for a
lamp and providing for the introduction of a plug
switch.
Kick. — A recoil.
Kick of Coil. — A discharge from an electro-magnetic
coil.
Kilerg. — One thousand ergs.
Kilo. — A prefix for one thousand times.
Kilo-Ampere. — One thousand amperes.
Kilo-Dyne. — One thousand dynes.
Kilo-Erg. — One thousand ergs.
Kilo-Gauss. — One thousand gausses.
Kilogramme. — One thousand grammes, equal to 2.67951
pounds troy or 2.20485 pounds avoirdupois.
Kilo-Henry. — One thousand henrys.
128 ELECTRICAL DICTIONARY
Kilo- Joule. — One thousand joules
Kilo- Volt. — One thousand volts.
Kilo-Watt. — One thousand watts.
Kilo- Watt-Hour. — The result in work equal to the ex-
penditure of exertion of one kilowatt in one hour.
Kilo- Watt Hour Meter. — A wattmeter that records.
Kilo-Weber. — One thousand webers.
Kinetic Theory of Matter. — A hypothesis assigning to
the molecules of matter the property of constant
motion or vibration towards or from one another
in paths lying within the radii of their reciprocal
attractions and repulsions.
Kinetics. — The science which treats of motions consid-
ered in themselves or apart from their causes.
Kinetoscope. — An instrument for obtaining the effect
of a panorama or moving objects by a display of
suitable pictures in rapid succession.
Knife-Break Switch.— A knife switch.
Knife-Switch. — A switch with narrow, deep, movable
arm, of copper or brass, which when making con-
tact is forced in between two springs connected to
one terminal.
Knob Insulator. — An insulator in the form of a knob
divided into two parts and utilized to support a
single wire by being clamped together with a sup-
porting screw.
Kynanizing. — A process used to preserve telegraph or
railroad timbers by the introduction of corrosive
sublimate into the pores of the wood.
ELECTRICAL DICTIONARY 129
Lag. — Dropping behind. To be tardy.
Lag of Motor Brushes. — A change of position of the
brushes on a motor's commutator in a direction op-
posed to its rotation for the purpose of obviating
sparking.
Lag of Resultant Flux. — In an induction motor, the dis-
placement in phase of the magnetic flux behind the
impressed magneto-motive force.
Lagging Electro-Motive Force. — The lagging of an elec-
tro-motive force, or component part thereof, behind
a current or flux.
Lagging of Current. — The retarding in phase of an al-
ternating current behind the pressure which pro-
duces it.
Laminated. — Made up of thin plates, as a laminated
armature core or converter core.
Laminated Core. — The subdivision of the core of an
armature, induction coil or converter into plates
insulated more or less perfectly from each other in
order to prevent the formation of Foucault cur-
rents.
Laminated Magnet. — A magnet equipped with a lami-
nated core.
Lamp Base. — That part of an incandescent lamp cham-
ber designed for the entrance into, the chamber of
the leading-in wires and which is supplied with
tw.o insulated plates of metal which are connected
with the leading-in wires.
Lamp Circuit. — A circuit having electric lamps or lamp.
130 ELECTRICAL DICTIONARY
Lamp Cut-Out. — An application for automatically cut-
ting a series connected arc lamp out of a circuit
when the carbons are entirely consumed.
Lamp Dimmer. — A reactive coil serving to vary the in-
tensity of incandescent lights connected with an
alternating circuit. A resistance coil in series with
lamps.
Lamp Efficiency. — Ordinarily a term used to signify
the watts consumed by a lamp per candle power de-
livered, but more properly expressed as the recip-
rocal of that, or the number of candles obtained
from an incandescent lamp per watt supplied to it.
Lamp-Hour. — A unit of commercial supply of electric
force. The volt-coulombs necessary to operate an
electric lamp for one hour.
Lamp Indicator. — An instrument serving in a central
station to indicate the presence of the proper volt-
age or potential difference on the mains. A lamp
serving on a telephone switch board which indi-
cates the calling or ringing off^by a subscriber.
Lamp Rod. — A rod contained in a common arc lamp
serving to support the positive carbon, and the rods
serving to support both carbons in a focusing lamp.
Lap Joint. — A joint in which the ends are overlapped
and secured in place by riveting or otherwise. A
joint secured by firmly lapping together the ends
of two conducting wires and then wrapping them
with a separate wire or by soldering.
Lap Winding. — A winding for disc and drum armatures
consisting of lapping back each lead of wire to-
wards the preceding lead upon the commutator end
of the armature.
ELECTRICAL DICTIONARY 131
Latent. — Not visible or apparent. Hidden.
Launch, Electric. — A launch, employing electric-motive
power.
Law. — The regular sequence by which certain phenom-
ena or effects follow certain conditions or causes.
The uniform relations according to which forces
act in producing effects or are manifested in
phenomena.
Law of Ohm. — The law which expresses the relation ex-
isting between current electro-motive force and re-
sistance in an active electric circuit. Ohm's law.
Law of Volta. — A law which states that in an electro-
chemical series the electro-motive force which ex-
ists between any two metals will amount to the
entire electro-motive force between all the metals
which intervene.
Laws of Becquerel. — Becquerel's.law for the magneto-
optic rotation of the plane of polarization.
Laws of Coulomb. — Laws for the force of magnetic at-
traction and repulsion between magnetized bodies
or adjacent magnet poles.
Laws of Faraday. — Laws of electrolytic decomposition.
Laws of Joule. — Laws of the production of heat by the
passage of an electric current through a circuit.
Lead. — A conductor which is insulated and leads to and
from a source. An insulated conductor employed
in a telegraphic system for leading to an instru-
ment, circuit battery or station. A conductor in a
multiple connected circuit which is connected to
the positive terminal of the source. An insulated
conductor in a system of electric distribution which
leads to a main, a station, source, feeder or testing
device.
132 ELECTRICAL DICTIONARY
Lead Accumulator. — A storage cell formed by the im-
mersion <3f two leaden plates in diluted sulphuric
acid.
Lead Burning. — Securing a junction by partially fusing
two lead plates together.
Lead-Covered Conductors. — Insulated conductors en-
cased in lead.
Lead of Brushes of Dynamo-Electric Generator. — An
augular deflection from the regular position in the
direction of the armature 's rotation which is given
to the brushes on the commutator for the purpose
of obviating sparking.
Lead of Brushes of Dynamo-Electric Generator. — The
angular change from the regular position to one in
an opposite direction to the armature's rotation,
made with the brushes on an electric-motor, when
the load is increased, for the purpose of obviating
sparking.
Leading-In Wires. — The wires which lead into a build-
ing or structure from an aerial circuit. The wires
through which passes the current into and out of
an incandescent electric lamp. Wires leading a
circuit into any enclosed space.
Leads. — The conductors which are connected to a
source's positive and negative terminals in a sys-
tem of parallel distribution or any system of elec-
tric distribution. Conductors through which the
current is led to or from any source or circuit.
Leak. — Any escape of energy by leakage.
Leakage. — A loss from leaks.
Leakage Drop. — The drop resulting in a circuit from
leakage.
ELECTRICAL DICTIONARY 133
Leakage, Electric. — The dissipation by degrees of a
current or charge arising from imperfect insula-
tion.
Leakage Flux. — That part of the field flux which pro-
duces no useful effect by reason of its failure to
pass through the armature of the dynamo or motor.
Left-Handed Armature-Windings.— rA sinistrorsal wind-
ing applied to the core of armatures.
Left-Handed Dynamo. — A dynamo whose movement is
counter-clockwise when observed from the pulley
end.
Left-Handed Helix. — A sinistrorsal helix or one wound
left-handed.
Left-Handed Motor.— (See Left-Handed Dynamo.)
Left-Handed Rotation. — A sinistral rotation. A rota-
tion opposed to the direction in which the hands
of a clock move.
Left-Handed Solenoid. — A solenoid whose windings are
sinistrorsal or rising from left to right.
Legal Ohm. — An ohm whose value was defined in 1884
by the Electrical Congress in Paris. The practical
unit of resistance equal to the resistance of a
column of mercury one square millimeter in cross
sectional area and 106 centimeters long at the tem-
perature of 0 degrees C. (32 degrees F.), as distin-
guished from the B. A. unit of resistance ohm, used
previously to 1884, or the international ohm, de-
fined in 1893 at Chicago by the International Con-
gress.
Length of Spark. — The air space traversed by a disrup-
tive discharge.
Lens. — Any transparent substance ground with two op-
134 ELECTRICAL DICTIONARY
posite regular curved surfaces and serving to bring
a beam or ray of light to a single focus.
Lever Brake for Car. — A style of car brake thrown into
action by means of a brake handle.
Lever Hook. — An automatic telephone switch hook de-
signed to hang the receiver on when not in use.
Leyden Jar. — A form of static condenser consisting of a
glass jar with metallic coatings placed opposite to
each other on the inside and outside of the jar.
Lichtenberg's Dust-Figures. — Figures produced on a
surface of shellac by rubbing over it the knob of a
Leyden jar or other excited electrode which leaves
upon the non-conducting surface an electrified
path to which a sprinkling of dried, powdered sul-
phur and red lead will cling, thus forming the fig-
ures.
Life Curve of Incandescent Electric Lamp. — A char-
acteristic curve showing the life of an incandescent
lamp by the use of ordina'tes which respectively
represent the life in hours and the candle power at
constant pressure.
Life of Electric Incandescent Lamp. — The number of
hours that an incandescent lamp will, when run-
ning under normal pressure, supply an efficient
light.
Light. — The source of the illuminating medium by
means of which objects are rendered visible and
distinct.
Light Load of Machine. — A load considerably less than
the capacity of a machine.
Lightning Arrester. — An appliance serving to protect
ELECTRICAL DICTIONARY 135
the apparatus in any electric circuit from the
damaging effects of a discharge of lightning.
Lightning-Arrester Board. — A board to which a light-
ning arrester is connected.
Lightning Red. — A lightning conductor in form of a
rod attached to the outside of any structure to pro-
tect it from a discharge of lightning by conducting
the electricity into the ground.
Lightning Stroke. — A discharge of electricity between
two clouds oppositely charged or from a cloud to
the earth.
Limit Switch. — A small switch provided on an electric
car connected in series with the brake discs, work-
ing automatically, and so contrived that it cuts out
the fields of both motors when the breaking cur-
rent is too great. A switch released by the action
of a clock, thereby cutting off the supply at a pre-
determined time.
Limiting Distance of Speech. — The distance to which a
circuit can be extended in a straight line before
telephonic communication becomes impracticable.
The point to which a telephone line may be ex-
tended and communication successfully maintained
subject to the electrical conditions of the circuit
and the character of the apparatus provided.
Line Dynamometer. — A dynamometer serving to indi-
cate whether a line, in course of overhead construc-
tion, has been drawn up to proper tension.
Line Insulator. — An insulator serving to support an
aerial line.
Line of Least Sparking. — The diameter on the commu-
tator determining the position of the brushes where
sparking is at its minimum.
136 ELECTRICAL DICTIONARY
Line Reactance. — A line conductor's reactance.
Line Section of Electric Railroad. — Any portion of an
electric railroad line, insulated in such manner
from other parts as to allow the separate control
of the supply of electric power.
Lines of Electrostatic-Force. — Lines of force assumed
to be present in an electrostatic field of force and
to which they give existence. Lines whose pro-
longation is in the direction in which the force of
electrostatic attraction or repulsion acts.
Lines of Magnetic-Force. — Lines of force which indi-
cate the distribution of magnetic-force. Lines of
force whose prolongation is in the direction in
which the force of magnetic attraction or repul-
sion acts.
Line-Man. — A person who erects and keeps line circuits
in repair and cares for the attending equipment.
Link-Fuse. — A plate of fusible metal in the shape of a
link, employed as a safety fuse, the ends of which
are suitable for connecting copper fuse-wire ter-
minals.
Link-Fuse Cut-Out. — A cut-out using a link fuse.
Liquid Compass. — A style of compass for ships, the
needle of which is suspended not only by gimbals,
but is also contrived in a manner which provides
for the checking of its oscillations by a surround-
ing liquid.
Liquid Flow. — The amount of liquid escaping from an
opening or passing through the cross-section of a
pipe or conduit in a specified time.
Liquid Resistance Load. — An artificial load for a dy-
namo consisting of a quantity of liquid, usually
salt brine, placed between suitable electrodes.
ELECTRICAL DICTIONARY 137
Liquefaction. — The conversion of a solid into a liquid
by the sole agency of heat; or in the case of gas,
by the abstraction of heat or by the combined
effect of pressure and low temperature.
Listening Cam. — A form of switch employed in a tele-
phone exchange to connect the operator's tele-
phone with a subscriber's line.
Lithanode. — A block of compressed lead binoxide, with
platinum connecting foils employed as an electrode
in a storage battery.
Live Wire. — A wire through which a current is flowing.
A wire connected with a source of electric power.
Load. — The work required of a machine. The amperes
of current delivered by a dynamo under any given
conditions.
Load-Diagram of Station. — A curve representing the
expenditure of current from a station for any
given length of time.
Load-Factor. — The relation of the average to the maxi-
mum load.
Loadstone. — (See Lodestone.)
Local Action of Dynamo-Electric Machine. — The loss
of energy sustained by a dynamo resulting from
the establishment of eddy currents in its core, pole
pieces and other conducting bodies.
Local Battery. — A battery which supplies a local cir-
cuit in telegraphy, where it is principally used ; the
battery being thrown in and out of action by a
relay; its current performing the work of actu-
ating the sounder and any other local or station
instrument.
Local Currents. — Currents within the metal parts of a
138 ELECTRICAL DICTIONARY
dynamo. A term sometimes applied to Foucault
currents.
Lock, Electric. — A lock which, by means of a distant
push button, is automatically released.
Locomotive, Electric. — A locomotive driven by elec-
tricity, or whose motive power is electricity.
Locomotive Head-Light, Electric. — (See Head-Light,
Electric.)
Lodestone. — Magnetic magnetite or naturally magne-
tized iron ore.
Log, Electric. — A device for electrically measuring the
speed or the distance traversed by ships.
Logarithm. — The power to which a given invariable
number called the base must be raised in order
to produce that number.
Logarithmic Curve. — A curve in which the ordinate's
rate of increase or decrease is proportionate to it-
self.
Long-Arc System of Electric Lighting. — A system of
lighting in. which long-arcs are used requiring high
electro-motive forces.
Long-Connection Armature- Winding. — A connection of
a two-circuit armature-winding effected in a man-
ner to produce electro-motive forces in each cir-
cuit by field poles of one polarity only.
Long Connection of Two-Circuit Gramme- Windings. —
A style of gramme-winding wherein the two cir-
cuits from brush to brush comprise conductors
which are influenced by one-half the poles only.
Long-Core Electro-Magnet. — An electro-magnet having
a long core.
Long-Distance Carbon Telephone Transmitter. — A tele-
ELECTRICAL DICTIONARY 139
phone transmitter of microphonic character em-
ployed on long distance lines.
Long-Distance Telephone Cabinet. — A closed cabinet
designed to exclude external noises and insure
secrecy in telephonic communications.
Long-Shunt Compound-Wound Dynamo-Electric Ma-
chine.— A dynamo, compound wound, and with its
shunt-field magnet coils forming a shunt to the
binding posts of the machine.
Loop-Circuit. — A term used sometimes for a circuit in
multiple or parallel arc. A circuit having one
wire going out and the other returning, thus dis-
tinguishing it from an earth-return circuit.
Loop-Switch. — A switch employed to open or close a
loop or for throwing it out of or into a main cir-
cuit. A switch employed to connect a branch office
with a duplex or quadruplex switch at a main
office, thus enabling messages to be sent and re-
ceived on the duplex or quadruplex system.
Loop-System of Parallel Distribution. — A system pro-
viding for the connection of two mains to a gen-
erator in a manner intended to equalize the drop
or pressure, and effected by connecting one main
directly to the generator at the home end, and
connecting the other, by a separate wire, at its dis-
tant end, to the generator.
Loop Winding. — A term applied to lap winding.
Loop-Winding of Alternator. — An alternator armature-
winding which provides for the laying of the wire
in loops on the outside of the armature core.
Loose Carbon Transmitter. — A telephone transmitter in
which loose carbon is used.
140 ELECTRICAL DICTIONARY
Loose Contact. — A contact formed by two or several
•surfaces reposing one upon another loosely or em-
ploying their weight only. A poor contact.
Loud-Speaking Telephone. — A term used to designate
a telephone characterized by the intensity of sound
emitted by its receiver.
Loudness. — The degree of intensity of sound corre-
sponding to the amplitude of vibration.
Low-Frequency. — A frequency of not many alterna-
tions comparatively, per second.
Low-Potential Current. — A term applied at times to a
current or low pressure circuit.
Low-Potential System. — Less than 300 volts ; according
to the National Electric Code.
Low-Resistance Magnet. — A magnet having low resist-
ance magnet coils.
Low-Speed Electric Motor. — An electric motor con-
structed to run at low speeds.
Low Tension. — Another term for low pressure.
Lubrication. — The act of making slippery for the pur-
pose of reducing friction between surfaces. Inter-
posing a thin film of material between two sliding
surfaces.
Luminescence. — The power which is to a certain degree
possessed by some bodies for giving out light, pre-
viously acquired by them, through exposure to
radiant energy or light.
Luminosity. — The quality of being luminous, and a
term sometimes applied to a source.
Luminous Absorption. — The absorption by bodies of
luminous energy in its passage through them.
ELECTRICAL DICTIONARY 141
Luminous Efficiency. — The relation which the luminous
radiation given out by a source, bears to the whole
radiant energy that such source emits in a specified
time.
Luminous Heat. — The radiation of heat attended by
physiologically effective frequencies.
Lux. — A standard for illumination in distinction to il-
luminating power. A unit of illumination equal
to the light projected on each square metre of the
inside of a sphere, the radius of which is one metre
from a bougie decimale situated at its center.
The normal illumination which one carcel will pro-
duce at the distance of one metre.
M.
Magnet. — A substance which possesses the power of
attracting iron ©r of producing magnetic flux. A
mass or body which has the property of attraction
for the opposite pole in another magnet or of re-
pelling the like pole or of inducing magnetism in
bodies susceptible to magnetization.
Magnet Coil. — A coil of insulated wire which surrounds
the core of an electro-magnet and through which
the magnetizing current flows.
Magnet Cores. — The bar or mass of iron wound with
insulated wire, which produces an electro-magnet
by the passage of the magnetizing current.
Magnetic Adherence. — A tendency noticeable in bodies
of iron to adhere to the poles of a magnet.
Magnetic Attraction. — The attraction of unlike mag-
netic poles for each other.
142 ELECTRICAL DICTIONARY
Magnetic Axis. — The line which connects the poles of
a magnet.
Magnetic Battery. — A term applied to a compound per-
manent magnet, constructed by clamping to single
iron pole pieces a number of single permanent
magnets.
Magnetic Belting. — A belting which provides for the
riveting of strips of sheet iron on the belt which,
by reason of the iron driving pulley being mag-
netized, the friction or grip upon the pulley is in-
creased by attraction.
Magnetic Blow-Out. — A device employed to extinguish
an arc by means of the flux produced by an electro-
magnet.
Magnetic Blow-Out Lightning-Arrester. — A lightning
arrester in which, by the action of the flux of an
electro-magnet placed in the circuit of an arc, the
arc when formed is extinguished.
Magnetic Circuit. — The course along which magnetic
flux passes.
Magnetic Circuit-Breaker. — A circuit breaker whose
action is produced by an electro-magnet.
Magnetic Circuit- Closer. — A circuit closer whose action
is produced by an electro-magnet.
Magnetic Closed-Circuit. — A circuit possessing the
magnetic polarity of iron. r-
Magnetic Clutch. — A clutch in which to obtain the fric-
tion required, magnetic attraction is substituted
for mechanical force.
Magnetic Concentration. — The freeing of ores from
their metals by magnetic attraction.
Magnetic Curves. — The representation of magnetic
ELECTRICAL DICTIONARY 143
lines of force on a sheet of paper which has been
sprinkled with iron filings, and obtained by gently
agitating the paper and holding it in the magnetic
field.
Magnetic Declination. — The angular deflection of the
magnetic needle causing it to rest at an angle with
the true meridian.
Magnetic Density. — That strength of magnetism which
is represented by lines of force per stated area of
cross section in a plane at right angles to the lines
of force.
Magnetic Dip. — A deviation from the horizontal by a
magnetic needle moving in the vertical plane.
Magnetic Divining Rod. — A small dipping needle used
to locate the approximate position of iron ore in
the earth.
Magnetic Equator. — A location on the earth's surface
where the magnetic needle maintains its horizontal
position. A line, approximately stated, equally
distant from the magnetic poles of the earth. The
aclinic line.
Magnetic Explorer. — A small coil of insulated wire em-
ployed to ascertain the position and extent of the
magnetic leakage of a dynamo or other electric
machine, and used in connection with the circuit
of a galvanometer or telephone.
Magnetic Fatigue. — The increase in the hysteretic co-
efficient of iron resulting from an assumed fatigue
following numerous cyclic reversals.
Magnetic Fatigue of Transformer. — The augmented
hysteretic loss of a transformer.
Magnetic Figures. — The grouping of iron filings ol>
144 ELECTRICAL DICTIONARY
tained upon paper or glass held near magnetic
poles.
Magnetic Flux. — Magnetic induction. The total lines
of force which flow through any magnetic circuit.
Magnetic Force. — The forces of attraction and repul-
sion which a magnet exercises; by some theories
identical with the forces of attraction and repul-
sion of electric currents.
Magnetic Friction. — The damping effect which prox-
imity to a magnet causes to the movements of a
body of metal.
Magnetic Fringe at Edge of Dynamo Pole Piece. — A
lateral diffusion of magnetic flux forming the out-
lying edge of a magnetic field, or an apparent
fringe of magnetic flux in the air around the poles.
Magnetic Gearing. — A species of friction gearing in
which magnetic adhesion is utilized.
Magnetic Hysteresis. — A molecular friction resulting
from magnetic change of stress. Magnetization
which lags behind the magnetizing force. A qual-
ity of a magnetic substance which is the occasion
of the absorption of energy upon the reversal of
its magnetization.
Magnet Induction. — The strength of magnetism which
is in an induced magnet, caused partly by the
polarized particles of material which surround it
and partly by the magnetic field. The density, in
air, of magnetic force; and in all magnetic ma-
terials it is the sum of the magnetic force and
the magnetic flux produced in the iron there-
by. Total density of magnetic flux. Magnetiza-
tion induced in a magnetizable substance when
brought into magnetic flux.
ELECTRICAL DICTIONARY 145
Magnetic Inertia. — The lack of power of a magnetic
core to acquire or to part with its magnetism in-
stantly.
Magnetic Intensity. — The intensity of the magnetiza-
tion of a body determined by the magnetic lines
of force passing through a unit area of the body,
the area being at right angles to the direction of
force.
Magnetic Joint. — A joint made between adjacent pieces
of iron forming parts of a magnetic circuit.
Magnetic Lag. — The tendency of a mass of iron to take
up magnetism slowly. The tendency of an iron
core to resist magnetization resulting in retarda-
tion. Magnetic retardation.
Magnetic Lightning-Arrester. — Any lightning arrester
using an electro-magnet. An electric-magnetic
blow-out arrester.
Magnetic Limit. — The temperature above which a mag-
netic substance cannot be magnetized.
Magnetic Lines of Force. — Lines along which a free
magnetic pole would be impelled. Lines of force
indicating the distribution of magnetic force.
Flux paths.
Magnetic Needle. — A needle or slender rod magnetized.
A magnetized bar of steel with a slight depression
at its center which permits of its being poised upon
a sharp pin so as to freely rotate or oscillate in a
horizontal plane ; sometimes so pivoted above and
below at its center as to enable it to move freely
in both vertical or horizontal planes.
Magnetic North. — The point of the horizon to which
the north-seeking pole of a magnet points.
146 ELECTRICAL DICTIONARY
Magnet Permeability.— The specific susceptibility of
any mass to magnetization. Magnetic inductive
capacity.
Magnetic Polarity. — Polarity acquired by a magnetiza-
ble substance from magnetic flux when subjected
to its influence.
Magnetic Poles. — Those members of a magnetic source
at which the flux enters or leaves.
Magnetic Potential.— The potential at any point of a
magnetic field is the work which would be done
by the magnetic forces of the field upon a positive
unit of magnetism as it moves from that point to
an infinite distance.
Magnetic Repulsion. — Repulsion reciprocally exerted
between like magnet poles.
Magnet Retentivity. — The resistance offered by a body
to any variation of magnetization. The property
of iron or other magnetic substance by which it
slowly receives and parts with a magnetic con-
dition. Hysteretic retention 'of magnetism after
the magnetizing force has been withdrawn.
Magnetic Saturation. — The maximum magnetic force
which can be permanently imparted to a magnetic
substance.
Magnetic Screen. — A box of soft iron, whose sides are
as thick as practicable, serving to protect bodies
within it from the action of a magnetic field ex-
ternal to it.
Magnetic Shield for Watches. — An iron case for the
reception of a watch and serving to shield it from
the influence of external magnetic flux.
Magnetic Sounds. — Small sharp sounds attending the
ELECTRICAL DICTIONARY 147
magnetization and demagnetization of easily mag-
netizable substances. The hum of a transformer.
Magnetic Sticking of Armature. — The adhesion of an
armature to the magnet poles caused by hysteresis.
Magnetic Stress. — The stress which magnetic lines of
force produce on substances which they flow
through. That quality of flux by virtue of which
magnetic strain is produced in bodies subjected to
its influence.
Magnetic-Vane Ammeter. — An ammeter in which a
fixed plate of soft iron is placed within the coil,
having freedom to move or serving as an axis, so
that when the field is excited the two repel each
other like polarity being induced in each, and
the motion of the movable soft iron indicates the
strength of the current.
Magnetic- Vane Voltmeter. — A magnetic vane wound
for high resistance.
Magnetic Voltmeter. — An instrument wherein a mova-
ble needle is deflected against the action of the
field of a magnet by the magnetic field of a current
proportional to the difference of the potential to
be determined.
Magnetization by Touch. — A method of magnetizing by
applying the poles of the inducing magnet to the
substance to be magnetized.
Magnetize. — To impart magnetic properties to a mag-
netizable substance.
Magneto. — An abbreviation for magneto-electric gener-
ator.
Magneto-Blasting Machine. — A magneto-electric ma-
chine serving to generate the currents employed in
blasting by means of electricity.
148 ELECTRICAL DICTIONARY
Magneto Call-bell. — A call bell principally used in tele-
phone systems and operated by a current from a
magneto-electric generator.
Magneto-Dynamics. — The branch of dynamics which
treats of the reciprocal influence of magnet poles,
Magneto-Electric Alternating Machine. — An alternator
the field flux of which is produced by permanent
magnets.
Magneto-Electric Machine. — A magneto-generator.
Magneto- Generator. — A dynamo electric machine the
field flux of which is produced by permanent mag-
nets.
Magnetophone. — A form of magnetic siren which pro-
duces sounds in a telephone by means of periodic
currents in its coils produced by a perforated disc
of metal rotating in a magnetic field. The "Busy"
signal.
Magneto-Telephone Transmitter. — A transmitter con-
sisting of a strong compound magnet having a coil
of insulated wire fixed in front of one of its poles
and an iron core constituting the pole piece of the
magnet.
Magneto-Therapy. — Asserted claims of electro-thera-
peutic effects obtained by applying magnets to the
human body.
Magnet Wire. — Insulated wire ordinarily cotton-cov-
ered, serviceable for winding magnets.
Main-Circuit Fuse. — A safety fuse employed in a main
circuit for its protection.
Main-Circuit Switch. — A switch introduced into a main
circuit.
ELECTRICAL DICTIONARY 149
Main Cut-Out, — A cut-out introduced into the circuit
of a main.
Main-Feeder. — The main feeder in a district. The
feeder with which is connected the standard pres-
sure indicator by whose pressure that, at the end!
of all the other feeders, is controlled.
Main-Line Cut-Out. — (See Main Cut-Out.)
Main Switch. — A switch which is connected to the
electric mains. The main switch which controls
a group of auxiliary switches.
Mains. — The parallel conductors which in a parallel
system of distribution carry the main current and
to which devices for transferring are connected.
Make. — To complete a circuit or close it.
Make-and-Break. — To complete and open a circuit al-
ternately.
Man-Hole of Conduit. — An opening in the surface of
the road bed, large enough to admit a man, and
communicating with an underground conduit.
Man-Power. — A unit of power represented by about 75
Watts and equal to the one-tenth of a horse power.
Marconi Rays. — Electro-magnetic rays used in Mar-
coni's system of wireless telegraphy.
Marine Galvanometer. — A Thompson's galvanometer
of the reflecting type employed on shipboard, the
needle of which is enclosed in a heavy iron box
to shield it from the motion of magnetized masses
of iron which otherwise would disturb the reading
of the instrument.
Mariner's Compass. — A compass so mounted as to be
suitable for use on shipboard.
150 ELECTRICAL DICTIONARY
Marked End of Magnet. — A term formerly employed
to indicate the north-seeking pole of a magnet.
Marked Pole of Magnet. — A term sometimes used for
the north-seeking pole of a magnet.
Mass. — A body of matter concreted, assembled or
formed into a lump. The quantity of matter which
a body contains.
Mass, Electric. — A term signifying quantity of elec-
tricity ; the unit mass representing such a quantity
as will operate at unit distance with unit force.
Mass Specific Resistance. — The resistance offered by
the known mass of a material, viz. : one gramme,
in the form of a circular sectional wire one metre
long.
Master Clock. — A central clock, in a system of time
distribution, which transmits the time of the sub-
ordinate clocks in its circuit.
Matt. — A term used in electro-plating and signifying
the appearance of the deposit of metal which is
interlaced and compactly massed in an electro-
plating of silver.
Matter. — That of which the sensible universe and all
existent bodies are composed, which has three di-
mensions and is perceptible to the senses.
Maximum. — Having the greatest value. A value
greater than any which precedes or follows it in
a succession of values.
Maximum Activity of Motor. — The rate of doing work
at the greatest possible capacity, or the activity
developed when the useful work performed is
equal to one-half the energy expended. The maxi-
mum activity.
ELECTRICAL DICTIONARY 151
Maximum Horizontal Intensity of Light. — The greatest
intensity of light emitted horizontally by a source.
Maximum Magnetization. — A term at times applied to
the greatest magnetic saturation.
Maximum Starting-Current of Motor. — The greatest
value attained by the starting current of a motor.
Mean. — Average. Having an intermediate value be-
tween two extremes.
Mean Annual Station-Current. — The average current
which a station delivers during a year.
Mean Current. — Time average of current strength. The
time average of current strength, in an alternating
current circuit, without respect to sine or direc-
tion.
Mean Electro-Motive Force. — Time average of electro-
motive force. The time average of the E. M. F. in
an alternating current circuit without respect to
sine or direction.
Mean Horizontal Intensity of Light. — The average
intensity of light in the horizontal plane of the
source.
Mean Spherical Candle-Power. — An average candle-
power equal numerically to the whole quantity of
light given out by a point source divided by 12,
566. The average candle-power of a source of
light given out in all directions.
Measurements, Electric. — The determinations of the
values of quantities as applied to electro-motive
force, capacity, resistance, energy, etc., in an elec-
tric circuit or instrument.
Mechanical Air Pump. — A mechanical device by means
152 ELECTRICAL DICTIONARY
of which the air is exhausted from, or compressed
into, any vessel.
Mechanical Characteristic of Motor. — A term at times
used to signify the torque and speed of a motor
as co-ordinates.
Mechanical Equivalent of Heat. — The mechanical
energy corresponding to a given quantity of heat
energy or the equivalent of mechanical energy in
heat which would be necessary to raise the tem-
perature of a unit mass of water to one degree
Fahr.
Mechanical Friction of Dynamo. — The frictions of the
brush, journals and air of a dynamo.
Mechanical Work. — The action of force through space
against resistance. The expenditure of energy
necessary to effect a change in the external form
of any material mass.
Medical Battery. — A medical induction coil.
Medical Induction-Coil. — An induction coil employed
in electro-therapeutics.
Meg or Mega. — A prefix meaning one million times.
Mega-Dyne. — One million dynes.
Mega- Joule. — One million joules.
Mega-Lines. — One million lines.
Mega- Volt. — One million volts.
Mega- Weber. — One million webers.
Megerg. — One million ergs.
Megohm. — One million ohms.
Megohm Box. — A box offering a resistance equal to one
million ohms.
ELECTRICAL DICTIONARY 153
Mercurial Air-Pump. — An air pump operated by mer-
cury to obtain high vacuum; used largely for ex-
hausting incandescent lamp chambers. The Spren-
gel or Giessler air pumps.
Mercurial Connection. — A style of easily adjustable
connection accomplished by supplying the poles of
one piece of apparatus with cavities containing
mercury into which the terminals of another piece
of apparatus are immersed, so that they may be
placed in circuit with each other.
Mercurial Contact. — An electric contact obtained by
means of mercury.
Mercury Cup. — A cup containing mercury and serving
as a mercurial contact.
Mercury Gauge. — A vacuum gauge which depends
upon the height of a mercury column for its in-
dications.
Mercury Tube. — A glass tube, sealed and containing
mercury so arranged as to give out fluorescent
light when shaken.
Metal-Cased Blake Transmitter. — A transmitter pro-
vided with a sheath of metal.
Metallic Arc. — An arc which forms between metallic
electrodes.
Metallic Circuit. — A circuit composed wholly of metal
and thereby distinguished from an earth-return
circuit.
Metallic Conductor. — A circuit composed of metal.
Metallic Electrolysis. — A mode of cataphoretic treat-
ment effected by making a contact of the part to
be treated with a metallic electrode connected to
the positive pole of a continuous current source,
154 ELECTRICAL DICTIONARY
while the negative pole is brought into contact
with some other part of the body, thus driving
cataphoretically the metallic salts, formed by elec-
trolysis at the anode, into the tissues beneath the
electrode.
Metallic Filament. — A metallic wire used in an incan-
descent lamp as a filament.
Metallic Resistance. — A term at times employed to sig-
nify the resistance of wires or conductors as op-
posed to the resistance of insulating materials.
Metallic Solution. — A solution of metallic salt.
Metallo-Chromes. — A name by which Nobili's rings are
known. Prismatic colors which make their ap-
pearance when, under certain circumstances, an
oxide is electrolyzed.
Metallurgy. — The art of working metals comprehend-
ing the whole process of the reduction or treat-
ment of metallic ores or metals.
Meteorites. — Fragments of solid matter in space which,
when coming within the earth's influence are at-
tracted by it, becoming incandescent by their
passage through the atmosphere.
Meteorology. — The science which treats of the atmos-
phere and its phenomena.
Meter, Electric. — An instrument employed to measure
the quantity of electricity which passes in a speci-
fied time through a consumption circuit.
Meter-Motor. — A small motor serving to operate an
electric meter.
Metre. — A measure of length equal to 39,370 English
inches or 39,368 American inches; the standard
of lineal measure intended to be the ten millionth
ELECTRICAL DICTIONARY 155
part of the distance from the equator to the north
pole.
Metre-Bridge — A slide style of Wheatstone's bridge,
the slide wire being one metre long.
Metric Factors. — Factors used to convert the units of
the metric system into those of other systems.
Metric System of Weights and Measures. — A system
of weights and measures founded on the gramme.
Mica. — A mineral substance more or less transparent
used for insulating and other purposes.
Micanite. — An insulating material made of mica and
shellac.
Micro. — A prefix meaning the one millionth.
Micro- Ampere. — The millionth of an ampere.
Micro-Coulomb. — The millionth of a coulomb.
Micro-Farad. — The millionth of a farad.
Micrometer Caliper. — A Micrometer gauge.
Micrometer Wire-Gauge. — A delicate form of wire
gauge fashioned with a fine thread screw and a
graduated head for making accurate measure-
ments of wire diameters.
Microhm. — The millionth of an ohm.
Microphone. — A style of telephone transmitter used on
a telephone in order that faint sounds may be made
audible and clear.
Microphone Relay. — An appliance by means of which
a telephonic message is automatically repeated
over another wire.
Microscope. — An optical instrument for examining ob-
jects which are too minute to be viewed by the
naked eye.
156 ELECTRICAL DICTIONARY
Micro- Volt. — The one millionth of a volt.
Mil. — A unit of length ; one thousandth part of a lineal
inch.
Mil-Foot. — A unit of resistance consisting of the re-
sistance of a foot of wire one thousandth of an
inch in diameter. The resistive standard by which
wires are measured or compared.
Milli. — A prefix meaning the one thousandth part.
Milli-Ampere. — The one thousandth of an ampere.
Milli- Volt.— The one thousandth of a volt.
Mine Explorer, Electric. — A small magneto-electric
generator used for direct blasting.
Miniature Incandescent Lamp. — A diminutive incan-
descent lamp serviceable for dental, surgical,
microscopic or decorative work.
Mining Locomotive, Electric. — An electric locomotive
used in mining work.
Minotto's Voltaic Cell. — A cell of the Daniell's type
having at the bottom of the ,cell a flat copper plate
underneath a mass of copper sulphate crystals, and
filled then with wet sand or saw dust, upon which
the zinc plate rests.
Minus Charge. — A negative charge.
Mirror Galvanometer. — A galvanometer the deflections
of whose needle are read by an image projected
by light reflected from a mirror attached to the
needle, or to a vertical wire carrying the needle.
Mirror Receiving-Instrument. — A receiving signaling
instrument, to whose needle or wire carrying it, is
attached a mirror, and which is used in sub-marine
telegraphy.
ELECTRICAL DICTIONARY 157
Mixed-Circuit Board. — A telephone switchboard con-
nected with mixed circuits, some of which being
metallic and the others ground return circuits.
Mixed Distribution. — A distribution of electric force
combining both parallel and series distribution.
Moderate-Speed Generator. — A generator constructed
to run at a moderate speed and in that respect
differing from a slow-speed generator.
Moderate-Speed Motor. — A motor constructed to work
at a moderate speed and in that respect differing
from a slow-speed motor.
Molar Attraction. — Gravitation. The attraction of
mass for mass as distinguished from molecular at-
traction.
Molecular. — Pertaining to molecules.
Molecular Accommodation. — A re-adjustment of the
molecules in paramagnetic material which results,
by continued repetition, in a diminution in the hys-
teretic friction in cyclic magnetization,
Molecular Agitation. — Quick mechanical vibration im-
parted to a mass of iron in order to diminish its
magnetic hysteresis.
Molecular Attraction. — The mutual attraction of mole-
cules for each other. Physical affinity. Cohesion
or adhesion.
Molecular Bombardment. — The collisions occurring be-
tween contiguous molecules quickened by heat.
The movement in straight lines of molecules from
the negative electrode and from side to side of a
vessel when the residual gas therein contained is
brought to a sufficient state of rarefaction ; their
courses being affected by heat or electric discharge,
158 ELECTRICAL DICTIONARY
which causes them to impinge upon the positive
electrode, producing luminous effects.
Molecular Resistance. — The resistance, which a mass
of an electrolyte offers when contained in an in-
sulating vessel, made of material of an equal spe-
cific gravity and which has two opposite parallel
conducting faces, at a distance of one centimetre
apart.
Molecular Vibration of Telephone Diaphragm. — The
molecular vibration which takes place in the dia-
phragm of a telephone under the influence of modi-
fications in the magnet's magnetization; marking
a distinction as to its molar vibration.
Molecule. — One of the invisible particles supposed to
constitute matter of any kind. The minutest
quantity of a compound substance that can have
existence.
Moment. — The product of the force by the shortest
distance from the point of rotation to the exten-
sion of the line of the force, when a force is applied
so as to tend to produce rotation around a point;
such distance being the perpendicular to the ex-
tension of the line through the point of rotation.
Moment of a Couple. — The effective power of a couple.
A force which tends to cause torsion around an
axis, as in the pulling or turning moment of the
armature of an electric motor upon its shaft.
Moment of a Magnet. — A magnet's polar length multi-
plied by the intensity of magnetism of one of its
poles.
Momentary Current. — A current which flows for a
short time only.
ELECTRICAL DICTIONARY 159
Momentum. — The quantity of motion in a moving body,
being always proportioned to the quantity of mat-
ter multiplied into the velocity. Impetus.
Mcnocyclic Armature. — The armature of a monocycle
generator having two sets of windings, one con-
stituting the main winding and corresponding to
that of an ordinary uniphaser, the other being
of smaller cross-section, having less turns, and be-
ing connected in diphase relation, to the center of
the main winding.
Monocyclic Generator. — A style of polyphase generator
having a monocyclic armature.
Monocyclic System. — An alternating-current distribu-
tion system, for electric lighting; being also capa-
ble of operating triphase induction motors. A
system for distributing alternating currents using
three wires; an ordinary uniphase pressure being
maintained between two of them while there is a
diphase pressure between either of them and the
third one.
Morse Recorder. — An apparatus which automatically
records the dots and dashes of the Morse tele-
graphic alphabet on a ribbon of paper drawn
under an indenting point of a striking lever at-
tached to the armature of an electro-magnet ; be-
ing thus distinguished from a Morse inker.
Morse System of Telegraphy. — A telegraphic system in
which by alternating makes and breaks of varying
duration the dots and dashes of the Morse alpha-
bet are reproduced and received by an electro-
magnetic sounder or other receiver.
Morse Telegraphic Sounder. — An electro-magnet which
160 ELECTRICAL DICTIONARY
produces, by the movement of its armature lever,
the dots and dashes of the Morse alphabet.
Motor Car, Electric. — An electrically driven car.
Motor Circuit. — A circuit supplying an electric motor
or motors.
Motor-Controlling Rheostat. — A rheostat which is con-
nected with a motor and serves to start the motor
or govern its speed.
Motor Cut-Out. — A cut-out in the circuit of a motor
provided for the purpose of throwing it out of
circuit.
Motor-Dynamo. — A motor electrically driven and firmly
connected to the armature of a dynamo for the
purpose of modifying the current.
Motor Starting-Box. — A box equipped with a starting
rheostat or controller.
Motor Starting-Rheostat. — An adjustable rheostat de-
signed to prevent an abnormal flow of current
through a shunt-wound motor when starting.
Motor Torque. — The rotary effort which an electric
motor develops.
Motor-Transformer. — A transformer which a motor
operates. A motor-generator, rotary transformer
or dynamotor. A dynamo-electric machine pro-
vided with two armature windings ; one serving to
receive current as a motor, the other to deliver
current, as a generator, to a secondary circuit.
Motor Truck. — The truck of an electric car equipped
with supports from which to suspend an electric
motor.
Moulded Carbons. — Carbons artificially manufactured
ELECTRICAL DICTIONARY 161
by subjecting carbonaceous substances to pressure
in a mould.
Moulded Mica. — A substance used for insulating and
made of finely broken mica formed into a paste
with insulating material and moulded, before cool-
ing, into the shape required.
Moulding Wiring. — Wiring effected by enclosing the
wires in suitably shaped moulding which is placed
on the walls or ceiling of a room.
Mouldings Electric. — Mouldings made of seasoned non-
conducting wood, longitudinally grooved, in order
to receive and hold insulated wires.
Mouth-Pieces. — Circular orifices communicating with
the air chambers placed over the diaphragms of
telephones, graphophones, gramophones or phono-
graphs to facilitate the application of the mouth
when speaking, in order to produce vibration in
the diaphragm.
Movable Secondary. — The secondary of an induction
coil which is movable instead of being rigid as in
most coils.
Multi-Circuit Arc-Dynamo. — A dynamo with an arma-
ture which has several circuits and intended to
avoid too great an electro-motive force on any one
circuit.
Multi-Circuit Arc-Light Generator. — An arc-light gene-
rator intended to furnish current to a number of
series-connected arc-circuits, being in this respect
distinguished from one intended to supply one cir-
cuit only.
Multiphase. — Containing more than one phase.
Multiphase Alternating-Currents. — Several separate al-
162 ELECTRICAL DICTIONARY
ternating currents which vary in phase by an
established amount.
Multiphase Alternator. — An alternator having the ca-
pacity to produce multiphase currents.
Multiphase Apparatus. — A term applied generally to
multiphase motors, alternators, or other receptive
apparatus serviceable on multiphase circuits.
Multiphase Induction-Motor. — An induction motor ope-
rated by rotating magnetic fields and serviceable
in connection with multiphase currents.
Multiphase Synchronous-Motor. — A synchronous alter-
nating-current motor furnished with multiphase
currents, as contrasted with an asynchronous or
induction multiphase motor.
Multiphaser. — A multiphase alternator.
Multiple- Arc -Circuit. — A term frequently applied to a
multiple circuit.
Multiple-Arc Connected Sources. — A battery consisting
of multiple connected sources.
Multiple Armature- Windings. — A term applied at times
to multiple-circuit armature windings.
Multiple Cable. — A cable having more than one con-
ducting wire or circuit.
Multiple Circuit. — A circuit in which the positive poles
of a number of separate sources and receptive de-
vices are connected to a single positive lead or
conductor; their negative poles being connected to
a single negative lead or conductor.
Multiple-Circuit Multiple-Wound Armature. — An ar-
mature providing a number of circuits between the
brushes, and in addition, a number of independent
ELECTRICAL DICTIONARY 163
windings which are connected to independent com-
mutator bars symmetrically interspersed.
Multiple-Pair Brush- Yoke. — A contrivance which holds
a number of pairs of brushes on the commutator
in a manner enabling them all to be simultaneously
moved or rotated on it.
Multiple-Parallel Circuit. — A term at times applied to
a multiple of parallel circuits.
Multiple Rheostat. — A rheostat the resistances of which
can be thrown into a circuit in multiple, thereby
increasing the carrying capacity as the resistance
decreases.
Multiple Running. — The running of generators in paral-
lel.
Multiple-Series. — Series groups connected in multiple.
Multiple-Series Circuit. — A circuit wherein a number
of individual sources or receptive devices or both
are connected in series in a number of separate
groups, these groups being subsequently connected
in multiple.
Multiple-Series-Connected Sources. — A number of in-
dividual electric sources connected in multiple-
series in such manner as to be able to act as single
sources.
Multiple Unit System of Railway Traction. — A system
of electric railroad wherein each traction unit is
supplied with its own independent motors, so that
all the units may be operated from a single point
collectively.
Multiple Windings. — Independent windings arranged
in a symmetrical manner upon the same armature
and insulated from each other, yet carried to dif-
ferent segments of the commutator.
164 ELECTRICAL DICTIONARY
Multiple- Wound Multiple-Circuit Armature. — A multi-
polar armature provided with a number of wind-
ings each winding having a number of circuits
between the brushes.
Multiple-Wound Two-Circuit Armature- Windings .—A
multipolar armature with a number of windings,
there being two circuits between the brushes for
each winding.
Multiple Working of Dynamo^Electric Machines. — A
term used sometimes to signify the parallel work-
ing of dynamo electric machines.
Multiplex Telegraphy. — A system of telegraphy which
provides for the simultaneous transmission of more
than two separate messages in opposite directions
and over a single wire from each end.
Multipolar Armature. — An armature employed in a
multipolar field.
Multipolar-Drum Armature- Windings. — Windings of a
drum armature adaptable to a multipolar field.
Multipolar Dynamo. — A dynamo having a multipolar
field.
Multipolar Field. — A field generated by several sepa-
rate magnets.
Multipolar Generator. — A multipolar dynamo.
Multipolar Motor. — A motor the field magnets of which
have several separate magnet poles.
Multipolar Railway-Generator. — A generator provided
with a multipolar field and serving to supply cur-
rent to trolley cars.
Multipolar-Ring Armature- Winding. — A winding of a
ring armature suitable for a multipolar field.
ELECTRICAL DICTIONARY 165
Municipal Series Circuit. — A series circuit serving to
distribute lights and adaptable for lighting streets.
Municipal System of Incandescent Electric Lighting.—
A system of distribution for incandescent electric
lighting wherein the individual lamps are con-
nected to the circuit in series, each lamp being
equipped with an automatic cut-out.
Mutual Flux of Transformer. — The magnetic flux
which flows through both of a transformer's coils
as contrasted with magnetic flux which may, when
excited, pass through one coil to the exclusion of
the other.
Mutual Induction — Induction which two adjacent cir-
cuits produce on each other by the mutual inter-
connection of their magnetic fluxes. Induction
caused in charged conductors adjacent to each
other, by the inter-connection of their electrostatic
fluxes.
Myograph. — An instrument employed to determine
nervous sensibility.
Myopia. — Near-sightedness.
Myria. — A prefix meaning ten thousand times.
N.
N. — An abbreviation for North-seeking magnet.
N. H. P. — An abbreviation for nominal horse power.
Name Plate. — A plate attached to a dynamo-electric
machine giving the maker's name and such other
information as weight, power, speed, current, etc.
Natural Law. — The co-relation of phenomena. The in-
166 ELECTRICAL DICTIONARY
variable sequence attending the manifestation of
phenomena.
Natural Magnet. — See Lodestone.
Nautical Mile. — A knot. A distance equal to 6,087 feet
or about 1.15 statute miles, and the one-twenty-
one thousand six-hundredth of the circumference
of the earth at the equator or one-sixtieth of a de-
gree of longitude at the equator.
Nautical Telegraphy. — Telegraphic communication at
sea between vessels and aboard single vessels.
Needle. — A word meaning a magnetic needle.
Needle Annunciator. — An annunciator which indicates
with a needle instead of by the fall of a drop.
Needle System of Telegraphy. — A system of telegraphy
which provides for the indication of the letters in
the alphabet and numerals by the oscillating move-
ment of a magnetic needle.
Needle Telegraph. — A term in general use signifying
the apparatus used in needle telegraphy.
Negative Brush of Motor. — The brush which is con-
nected with the negative terminal of a dynamo. -
Negative Electricity. — A phase of electric excitement,
observable, for instance, when resin is rubbed with
silk.
Negative Electrode. — The electrode which is connected
to a source's negative terminal.
Negative Feeder. — Feeders which connect the negative
mains with the negative poles of a generator.
Negative Plate of Storage Cell. — The plate of a storage
cell which, by the action of a current, becomes
partly covered with a coating of spongy lead. The
plate of a storage cell which is connected to a
ELECTRICAL DICTIONARY 167
charging source's negative terminal, constituting
therefore the negative pole of the cell on discharg-
ing.
Negative Plate of Voltaic Cell.— The electro-negative
element of a voltaic couple. That part of a voltaic
cell's plate above the liquid which becomes the
positive pole of the cell.
Negative Pole of Source. — The pole of an electric source
through which the current is supposed to go in
or to pass back into the source, after having passed
through the circuit connected to the source.
Negative Side of Circuit. — That side of a circuit which
is opposite the positive sides. The side of a circuit
into which current flows after having performed
a duty or function. That side of a circuit which
is connected with the negative pole of a source.
Net Efficiency. — The ultimate efficiency of machines or
transferring contrivances through which energy
must pass in distinction from the separate effic-
iency of each machine or device.
Network of Conductors. — A term used to describe a
number of conductors so interconnected as to re-
semble a net in appearance.
Neutral Ampere-Meter. — An ampere meter in a three-
wire system of distribution which is connected
with the neutral bus-bar.
Neutral Conductor. — In a three-wire system, the neu-
tral wire.
Neutral Feeder. — The feeder connected with the neu-
tral bus-bar in a three-wire system.
Neutral-Line of Magnet. — The equator of the magnet.
Neutral Point. — A term signifying indifference.
168 ELECTRICAL DICTIONARY
Neutral Points of Magnet. — Points which are nearly
midway between the poles of a magnet.
Neutral Salt. — A salt devoid of basic o-r acid properties.
Neutral Wire. — The wire, in a three-wire system of
distribution, which is connected with the neutral
dynamo terminals. Of a three-wire system, the
balance wire.
Nickel Bath. — An electrolytic bath which contains a
salt of nickel easily electrolyzable, having a nickel
plate which serves as the anode of the battery, and
which is immersed in a liquid in proximity to the
article to be plated, which serves as the cathode.
Nipple of Negative Carbon. — A diminutive elongation
of the carbon which occurs on the surface of the
negative carbon facing the crater of the positive
one while the arc is going.
Noise. — A confused collection of discordant tones.
Clamor. Din.
Noisy Arc. — A voltaic arc which emits frying and hiss-
ing sounds during maintenance.
Nominal Candle-Power . — A term used at times signify-
ing the candle-power of a luminous source obtained
in a suitable direction.
Non-Arcing Fuse. — A fuse wire which, by reason of
being made of non-arcing metal, or encased in an
air-tight tube, blows without forming a voltaic arc.
Non-Arcing Metal. — An alloy composed of the blend-
ing of a certain assemblage of metals, which will
not, under some conditions allow an alternating-
current arc to be maintained between them.
Non-Conductor. — A material of low conductivity or
high electric resistance.
ELECTRICAL DICTIONARY 169
Non-Ferric. — Without iron.
Nan-Ferric Inductance. — An inductance of a circuit de-
void of iron or not associated magnetically there-
with. The inductance possessed by a coil which
has a non-magnetic core.
Non-Ferric Magnetic Circuit. — A magnetic circuit with-
out iron, or one which contains only non-magnetic
materials, such as copper, wood, air, etc.
Non-Homogeneous Current-Distribution. — That distri-
bution of current which flows through a conduc-
tor, wherein there is over any cross-section of it,
a current of unequal density.
Non-Magnetic Steel. — Alloys of irons incapable of be-
ing magnetized, composed of such substances as
manganese or nickel steel.
Non-Oscillatory. — Not changing the direction of mo-
tion ; not oscillating in motion.
Non-Polar Transformer. — A term applied to a closed
iron-circuit transformer.
Non-Polarizable. — Devoid of the ability of being polar-
ized.
Non-Polarized Armature. — An armature composed of
soft iron and which, regardless of the direction
in which the current flows through the coils, is
drawn towards the poles of an electro-magnet,
when the circuit is completed.
Non-Synchronous Motor. — An alternating current
motor possessing the ability to start at any load;
one not forced to run in concurrence with its driv-
ing current.
Normal. — Consonant with rule. Regular.
X70 ELECTRICAL, DICTIONARY
Normal Current. — The force of current at which a sys-
tem is intended to work.
Normal Voltage. — The voltage at which a system is in-
tended to work.
North-Seeking Magnetic Pole. — The pole of a magnet
which points to the earth's north geographical
pole.
Nose Suspension of Motor. — The hanging of a motor
in a car truck by a hook from above instead of
from a bar and spring from underneath.
Null of Zero Method. — Any method by which compari-
sons or measurements are secured, the accuracy of
the measurements being determined by the de-
flection of the galvanometer being null or nought.
For example, the Wheatstone bridge.
0.
0. — An abbreviation for ohm.
0. K. — A telegraphic signal meaning "yes" or "all
right."
Obtuse Angle. — A term applied to an angle greater
than a right angle or containing more than 90
degrees.
Occluded-Gas Process. — A method of depleting a
vacuum tube or incandescent electric lamp cham-
bers of the residual air, and which is effected by
the application of a high degree of temperature
to the tube or lamp before sealing, and while con-
nected with the pumps.
Octo-Polar Dynamo. — A multipolar dynamo the field
of which possesses eight poles.
ELECTRICAL DICTIONARY 171
Octo-Polar Field. — A field resulting from the flux of
eight distinct magnetic poles.
Off Position of Switch. — The position assumed by a
switch when throwing off, from the working cur-
rent, a section of a circuit,
Ohm. — The practical unit of resistance; electro-mag-
netic units 109 degrees C. G. S. A resistance such
as would confine the electric flow under an electro-
motive force of one volt to a current of one ampere
or coulomb per second.
Ohmage. — The value of a circuit's resistance expressed
in ohms.
Ohmic. — Pertaining to the ohm.
Ohmic Drop. — The drop in pressure resulting from
ohmic pressure.
Ohmic Resistance. — A resistance in distinction from
spurious resistance, or counter-electro-motive force.
Ohm Meter. — An instrument serving to measure di-
rectly the resistance of a conductor or of any sec-
tion of a circuit through which a strong current
is flowing.
Ohm Mile. — A standard of conductivity consisting of
wires one mile long and which offer a resistance of
one ohm at a standard temperature. A mass of
material, which would at a standard temperature
enable a wire of that material to show a resistance
of one ohm.
Ohm's Law. — The basic law which expresses the rela-
tions between current electro-motive force and re-
sistance in active electric circuits.
Oil Insulator. — An insulator containing oil.
172 ELECTRICAL DICTIONARY
Oil Paper. — A material for insulating composed of
paper which has been saturated with an insulating
oil.
Oil Transformer. — A transformer put into oil for the
purpose of securing and maintaining high insula-
tion.
Okonite. — A kind of insulating material.
One-Layer Armature- Winding. — An armature winding
which consists of one layer of wire only.
Opacity. — Not possessing the property of transparency.
Open-Arc. — A voltaic arc not enclosed.
Open Car- Wheel. — A style of car-wheel containing per-
forations in the space between the flange and the
journal.
Open Circuit. — A circuit which is broken.
Open-Circuit Battery. — A battery employed in open-
circuit work, its principal requirement being that
it must not run down or become exhausted when
left on open circuit.
Open-Circuit of Triphase Connections. — The triphase
circuit's star-connection.
Open-Circuit Thermostat. — A thermostat employed on
an open-circuit.
Open-Circuit Transformer. — A transformer the mag-
netic circuit of which is completed to some extent
through air.
Open-Circuited. — Having an open or broken circuit.
Open-Coil Armature. — An armature which has some of
its coils on open circuit during a part of the ar-
mature's rotation.
Open-Coil Drum Dynamo-Electric Machine. — An open-
ELECTRICAL DICTIONARY 173
coil dynamo-electric machine with a drum-wound
armature.
Open- Wire Symmetrical Twist. — A method of running
aerial telephone wires with a view to obviating
cross-talk; all the wires on a pole being twisted
along the line.
Open Work. — Open wiring.
Opening a Circuit. — The breaking of a circuit.
Opening Shock. — The shock resulting in an electric
circuit containing self-induction upon opening or
breaking the same.
Operator's Set. — A telephone set used by the operator
at a central station.
Optics. — The science which treats of the phenomena of
light.
Optical Efficiency of Light. — The relation between the
obscure and luminous radiation.
Optical Strain. — A defect in a plate of any transparent
medium produced by the action of a stress and
accompanied by a modification in the optical prop-
erties of the medium.
Ordinate. — The distance of any point from the axis of
abscissas, in a system of plane co-ordinates, meas-
ured parallel to the axis of ordinates.
Ordinary Relay. — A relay not polarized.
Oscillating Current. — A current periodically alternat-
ing.
Oscillation. — A vibration or movement back and forth.
Oscillations, Electric. — The rapid and sudden alterna-
tions, in static electricity, attending the discharge
of a static condenser ; the discharge being of a dis-
174 ELECTRICAL DICTIONARY
ruptive character, but appearing to consist of a
number of discharges which alternate in direction
and produce electro-magnetic ether waves of the
same nature as light waves; the latter, however,
being shorter and much less rapid.
Oscillator. — A device which produces oscillations.
Oscillator, Electric. — A device serving to produce
electric currents of a steady period without regard
to any variations in its driving force.
Oscillatory Dynamo. — A dynamo which has electro-
motive forces generated in its armature coils by a
vibratory or oscillatory movement through a mag-
netic field.
Osmose. — The equal blending of liquids with varying
densities through the pores of a separating
medium.
Osmose, Electric. — When two liquids are separated by
a porous diaphragm and a strong current of elec-
tricity is passed through from the liquid on the
one side .through the diaphragm, to the liquid on
the other side, the liquid on the side to which the
current is passing rises in level.
Outboard Bearing. — A journal bearing extended be-
yond the base frame of a machine in order to ob-
tain sufficient support for a long or heavy shaft.
Outboard Bearing of Dynamo-Electric Machine. — A
bearing extended beyond the base frame of a
dynamo electric machine in order to properly sup-
port the motor.
"Out-door" Transformer. — A transformer located out-
side of a building at a suitable place.
ELECTRICAL DICTIONARY 175
Outgoing Current. — The current which goes out from
a station over a line.
Outlet. — A point in a wall or ceiling where branch
wires come out and which are to be connected to
a switch, lamp, etc. The places about a building
where the fixtures or lamps are attached.
Outlet Block. — A fuse block located at or close to an
outlet. A block which has an outlet protected by
a fuse wire.
Outlet Box. — A box located at or close to an outlet to
facilitate the making or changing of electric con-
nection with the outlet conductors.
Output. — The useful energy which any machine gives
out.
Output of Dynamo-Electric Machine. — The electric
power of current which a dynamo electric gene-
rator develops at the delivery terminals and in-
dicated in volt-amperes, kilo-watts or watts.
Outrigger. — An arm attached at right angles to a pole
in order to support it.
Outrigger for Arc-Lamp. — A fixture attached at right
angle to the vault of a building for the purpose
of suspending an electric arc-lamp therefrom.
Outside Wiring. — The wiring outside of a building or
structure for a circuit.
Over-Compounded. — Compound winding of such a
character on a dynamo-electric machine that the
voltage at its terminals is caused to increase under
a greater load.
Over-Compounded Dynamo. — A dynamo, the magneto-
motive force of whose series coils compensates for
the drop in the armature and for the drop in a
176 ELECTRICAL DICTIONARY
conductor ranging from the generators to the
motors, thus allowing the outer conductors to be
considered as an extension of the armature wind-
ing, whereby the generator delivers a constant
pressure at its terminals at the motor.
Overhead Conductor. — A conductor erected overhead.
Overhead Feeders. — Feeders erected overhead.
Overhead Switch. — A switch placed overhead and serv-
ing to control an overhead circuit, also one placed
on a car over the motorman for his ready manipu-
lation.
Overhead Trolley-System. — A system in which the cur-
rent that propels an electric street car is taken
from a wire overhead.
Overhead Trolley- Wire. — A common aerial trolley wire.
Overlapping Winding of Alternator Armature. — A
winding by overlapping the successive coils in
contrast to one by mechanically separating suc-
cessive coils.
Overload. — A load having an abnormal value. Too
heavy a load.
Overload of Electric Motor. — A load in excess of that
which an electric motor is designed to carry with
its greatest operating efficiency. A load so ex-
cessive as to produce damage to the motor by heat-
ing.
Overload Switch. — A switch provided in order to open
a circuit automatically in case of an overload.
Overloaded Conductor. — A conductor loaded with an
electric current greater than that for which it was
designed.
ELECTRICAL DICTIONARY 177
Over- Winding of Series Motor. — A series motor having
too strong a field winding.
Over- Wound Motor Field. — A motor field in which the
full strength is developed with much less current
than usually required. An over-compounded
motor field. •
Ozone. — Oxygen in an active or highly electro-negative
state.
Ozonizer. — An apparatus employing electric discharges
to produce ozone.
P.
Pacinotti Projections. — Teeth in an armature core
projecting radially from the central shaft in a
manner to form slots or chambers for the insertion
of the armature coils.
Pacinotti Ring. — An armature core in the form of a
ring with projections and serving for the recep-
tion of the armature winding in Pacinotti 's gene-
rator.
Packing of Telephone Dust Transmitter. — The forming
into a cake of carbon dust in a transmitter which
materially impairs the efficiency of the apparatus.
Palladium. — A metal of the platinum group.
Palladium Alloys. — Divers alloys composed of pal-
ladium with metals principally having no para-
magnetic properties and used where desirable to
obtain freedom from the disturbance of powerful
magnetic fields, as, for instance, the hairsprings
of watches.
178 ELECTRICAL DICTIONARY
Panel Board. — A switchboard built and connected in
panels.
Panel of Switchboard. — A sub-section of a panel board.
Paper Cable. — A cable insulated with paper.
Paper Carbon. — Filaments for incandescent lamps.
made of carbonized paper.
Paper Insulation. — Insulation made of paper.
Parabola. — A curve known as one of the conic sections
and formed by the intersection of the surface of a
cone with a plane parallel to one of its sides.
Parabolic Reflector. — A reflector of light or a mirror
whose surface is a paraboloid and which reflects
in lines parallel with each other the rays of a light
located at its focus.
Paradox. — Something seemingly absurd or contradic-
tory ; but yet true in fact.
Paraffine. — A hydro-carbon very valuable for insulat-
ing. The wax from mineral oils.
Paraffined Wire. — Wire whose textile covering is
coated with paraffine.
Paraffining. — Coating with paraffine.
Parallel Circuit. — A term signifying multiple circuit.
Parallel Connected Triphasers. — Several triphasers
which are connected parallel with an ordinary set
of triphase mains.
Parallel Coupling. — A term applied at times to the par-
allel connection of generators.
Parallel Distribution. — A distribution of electricity
wherein the receptive contrivances are adjusted
between two or every two of a number of parallel
conductors running to the limits of the system.
ELECTRICAL DICTIONARY 179
Parallel Feeding. — Supplying the necessary current to
a number of receptive contrivances connected in
parallel.
Parallel Series. — A term used signifying a multiple-
series connection.
Parallel Transformer. — A transformer employed in a
parallel system of distribution or connected with
parallel mains.
Parallel- Working of Dynamo-Electric Machines. — Sev-
eral dynamos operating parallel.
Paramagnet. — A magnet obtained from the magnetic
influence of iron or other magnetic substance.
Paramagnetic. — Having magnetic properties or the
capacity to concentrate magnetic lines of force.
Paramagnetic Permeability. — Susceptible to penetra-
tion by magnetic force.
Partial Contact. — Defective contact producing high
resistance in two telegraphic circuits.
Partial Disconnection. — A defective metallic contact,
or lack of perfect metallic connection.
Partial Vacuum. — A vacuum not complete.
Party Lines for Telephone Service. — Lines by which a
number of subscribers in one circuit are connected,
as distinguished from lines assigned to single sub-
scribers. Or, lines by which a number of tele-
phonic stations are connected together in contrast
to those which connect each station through an ex-
change.
Parz Gravity Cell. — A couple consisting of zinc-carbon
used with common salt or sulphate of magnesia
and sulpho-chromis salt, the different density of
the liquids keeping them separated in the cell.
180 ELECTRICAL DICTIONARY
Paste Joint for Lamp Filament. — A species of joint
made of a moist hydro-carbon paste and then car-
bonized, and used between leading-in wires and
the ends of a lamp filament.
Pasted Secondary Cell. — A secondary cell where a
paste or cement composed of the active material
is applied to the surface of the grid.
Path of Magnetic Leakage. — A path followed by es-
caping magnetic flux from the main path where it
is usefully employed.
Patrol Alarm-Box. — A box designed for the use of a
patrol in telegraphic or telephonic systems where-
by any call or alarm can be given.
Paying-Out. — Passing out submarine cable while it is
being laid from a ship.
"Pea" Lamp. — A very diminutive form of incandes-
cent lamp.
Pear Push. — A push contact resembling a pear in shape
and attached to the end of a pendant flexible cord.
Peltier Effect. — The heating effect produced by the
passing of a current through the junction of two
unlike conductors.
Pencil Microphone. — A carbon microphone, the loose
carbon being in the form of a pencil or pencils.
Pendant Cord. — A flexible conductor by means of
which a pendant lamp or push is supplied with
current.
Pendant, Electric. — A suspended fixture upon which
an incandescent lamp or contact is supported and
held in a socket attached to it.
Pendulum, Electric. — A pendulum which the inter-
mittent action of an electro-magnet actuates, the
ELECTRICAL DICTIONARY 181
pendulum itself opening and closing the circuit by
means of a point at its lower extremity contacting
as it swings to and fro through a globule of mer-
cury, thus opening and closing the circuit.
Penthode Working. — A five-way method of telegraphic
working which is obtained by the employment of
the synchronous multiplex system of Delaney.
Percentage Conductivity. — The percentage of conduc-
tivity of a conductor based upon the Mathiessen
standard.
Percentage Conductivity of Wire. — The conductivity
of wire, taking as a standard the conductivity of
pure copper. The conductivity of wire based upon
the Mathiessen standard of conductivity for
copper.
Perforated Armature. — An armature having perfora-
tions for the introduction of the coils.
Period. — The time necessary to effect the completion
of a periodic motion. The full alternation of an
oscillatory discharge or of an alternating current.
Period of Vibration. — The time consumed by the ex-
ecution of a complete vibration or movement back
and forth.
Periodic. — Pertaining to a period.
Periodic Alternating Electromotive Force. — An electro-
motive force with periodically varying direction.
Periodic Current. — A current with periodically varying
strength or direction. A current alternating peri-
odically.
Periodicity. — The state of having regular periods in
changes. The rate of succession in fixed phases.
182 ELECTRICAL DICTIONARY
Periodicity of Alternation. — The rate of succession of
alternations per second or per minute. The fre-
quency.
Peripheral Speed.— The rapidity of rotation as indi-
cated by a point on the circumference of a revolv-
ing wheel or cylinder.
Peripheral Velocity. — The rate of peripheral speed.
Peripheratic Region. — A region embracing other re-
gions within itself.
Permanency, Electric. — In electric current conductors
the power to retain conductivity unaffected by
lapse of time.
Permanent Intensity of Magnetization. — The inten-
sity of a permanent magnetization produced in
hard steel, in contrast to that temporarily pro-
duced in soft iron.
Permanent Magnet. — A term applied to a hardened
steel magnet possessing high magnetic retentivity.
Permanent-Magnet Voltmeter. — A voltmeter which
under the united action of a coil and a permanent
magnet against the pull of a spring measures dif-
ferences of potential by means of the movement of
a magnetic needle.
Permanent Magnetism. — Magnetism which permanent
magnets possess.
Permanent Magnetization. — A term signifying mag-
netism caused in a body of hard iron or steel when
subjected to the influence of a magnetic field.
Magnetization existing in a permanent magnet.
Permeating. — The penetration of magnetic flux. The
close interstitial permeation of a magnetizable
mass.
ELECTRICAL DICTIONARY 183
Permissivity. — Permittivity.
Perpendicular. — A line at right angles to a given line
or surface.
Personal Equation. — An er^or of observation peculiar
to the individual and due to his optical or mental
condition.
Petticoat Insulator. — An insulator having at its lower
end a deep groove resembling a petticoat. A single
cup telephone or telegraph insulator.
Phase. — The interval of time elapsing from the time
a particle. moves through the middle point of its
course to the instant when the phase is to be
stated ; exhibited in wave, oscillating and simple
harmonic motion. One complete oscillation.
Phase Indicator. — An instrument which indicates when
the pressure of an alternator is in phase with that
of the circuit it is to be connected with. A syn-
chronizer.
Phase of Vibration. — The position of the molecules in
motion in a vibration at any moment of time pend-
ing the wave period as contrasted with their mean
position.
Phase-Splitter. — An instrument whose function is to so
affect an incoming alternating current that when it
passes out again it does so in different branches
and as a number of currents of different phase.
An instrument serving to cause difference of phase
in currents by which a single phase induction-
motor is enabled to start itself.
Phase Splitting. — The act of causing an alternating
current to split up into a number of currents dif-
fering in phase.
184 ELECTRICAL DICTIONARY
Phase Transformation. — A change of phase effected by
means of a transformer which transforms two
phase currents into three phase currents or the
reverse.
Phase- Windings. — The individual windings on a poly-
phase motor's armature.
Phenomenon. — Any appearance or thing visible in
nature or the knowledge of the existence of which
is acquired.
Phone. — An abbreviation for telephone. A telephone
communication.
Phone. — To communicate by telephone.
Phonic Wheel. — A single form of small motor consist-
ing of a toothed wheel of soft iron and operated
in synchronous rotation by electric excitation pro-
duced over a telegraphic line, and used in the syn-
chronous multiplex telegraph system of Delaney.
Phonograph. — An instrument which records and re-
peats speech or sounds.
Phonograph Record. — A record of speech or sounds
taken by the phonograph.
Phonoplex Telegraphic-Receiver. — A particular kind of
telephone receiver used in connection with phono-
plex telegraphy, which is affected by short cur-
excitations ; but not by prolonged ones.
Phonoplex Telegraphy. — Double telegraphic transmis-
sion over a single wire without interruption; ef-
fected by the superposition of telephonic currents
upon common Morse currents which set a modified
telephonic receiver in action, thus obtaining simul-
taneous transmission.
ELECTRICAL DICTIONARY 185
Phosphorescence. — The capacity to exhibit faint light
without sensible heat.
Phosphorescent Glow. — Phosphorescent light given out
by the residual gas in a vacuum chamber for a few
moments after the electric charge leaves it.
Photo-Chemical. — Pertaining to photo-chemistry.
Photochemistry. — The science treating of the chemical
action of light.
Photo-Electric. — Pertaining to the united action of
light and electricity.
Photo-Electric Cell. — A cell having the capacity to
cause difference of potential when its opposed sur-
faces are unequally exposed to light.
Photo-Electric Impulsion Cell. — A photo-electric cell
whose sensibility to light has been impaired; but
which can be re-established by gentle mechanical
agitation or by electro-magnetic excitation.
Photo-Electricity. — A variation of electric potential re-
sulting from light action.
Photo-Engraving. — Engraving done by means of light.
Photo-Fluoroscopy. — An image photographically pro-
duced upon a fluoroscopic screen.
Photographic Negative. — An image the lights and
shadows of which are the opposite of those of the
original.
Photographic Positive. — An image the lights and
shadows of which correspond to those of the
original.
Photometer. — An apparatus employed to determine the
intensity of the light emitted by a specified light
or by any source of illumination.
186 ELECTRICAL DICTIONARY
Photometer Bar. — A photometer in which the lights to
be compared are placed at or opposite to the ends
of a bar or scale of certain length, generally 60
to 100 inches, the bar having a photometer screen
which indicates the relation of the intensity of the
lights compared by the distance of the screens
from their sources.
Photometer Bench. — A photometer bar with accom-
panying photometric apparatus or without it.
Photometer Box. — A box having the light excluded and
in which the photometer screen is put.
Photometer Disc. — A photometer screen.
Photometer, Electric. — An instrument serving by
means of electricity to measure the intensity of
light.
Photometer Screen. — A -screen, opaque or transparent,
serving in a photometer to measure the intensity
of light; the two illuminations to be compared
being projected upon it.
Photometric. — Pertaining to a photometer.
Photophone. — An instrument serving to transmit sound
along a ray of light in place of a conducting wire.
Photophore. — An instrument used for making examina-
tions of the cavities of the body by means of a
small incandescent lamp adjusted in a tube with
a convex lens and concave mirror.
Physical Change. — Any modification in the forms of
matter occurring by reason of a re-adjustment
of its molecular assemblage without forming
new molecules; in contradistinction to chemical
changes.
Physical. — Pertaining to nature.
ELECTRICAL DICTIONARY 187
Piano, Electric. — A piano played by means of an elec-
tric motor or electro-magnets, which excite the
mechanism controlling the hammers which strike
the strings.
Pickle. — An acid solution serving to clean metallic sur-
faces before electro-plating.
Pile. — A voltaic or galvanic battery. A name given to
batteries only which have plates superimposed and
not containing vessel; the Dry Pile, for instance,
or Volta's Pile.
Pilot Lamp. — A lamp traversely connected to a dy-
namo's terminals and serving to indicate about
what pressure it is producing. A lamp employed
on a central station dynamo to indicate by the
intensity of the light emitted, the difference of
potential at the terminals of dynamo.
Pilot Motor. — A diminutive motor which leads or sets
in operation a working one. A small motor ar-
ranged to actuate the controller of a large motor.
Pipe Conduit. — A conduit consisting of metallic pipes
incased in or lined with a cementing compound.
Pitch. — The distance from center to center of any two
adjacent teeth of gearing measured on the pitch-
line. The distance measured on a line parallel to
the axis, between two adjacent threads of a screw.
The succession of musical tone vibrations. The
frequency of a tone produced electrically. The
distance, on dynamo armature, between successive
corresponding conductors. The number of coils in
which advance should be made in effecting- end
connections between the coils of an armature wind-
ing divided into segments.
188 ELECTRICAL DICTIONARY
Pitch Line. — A line encircling the surface of an arma-
ture through the center of the inductors' length,
which are put thereon.
Pith. — A light and soft spongy substance forming the
central part of exogenous trees and plants.
Pith Balls. — Balls made of pith and employed in the
construction of electroscopes and for other pur-
poses in static electricity.
Pith-Ball Electroscope. — An electroscope the indica-
tions of which are shown by the attractions and re-
pulsions of pith balls.
Planimeter. — An instrument designed to measure by
mechanical means, and at once, the area of any
plane figure drawn on paper, and so contrived that
when the tracer has passed over the irregular out-
line of a figure the index shows the area of the
figure.
Plant. — The fixtures, tools and machinery necessary to
carry on any mechanical business. An installation.
Plant Efficiency. — The efficiency of an electric plant.
The efficiency of a plant and which is to be dis-
tinguished from the distribution system by which
it may be operated or which it operates.
Plant Efficiency of Motor. — The efficiency of motor
in a plant considered apart from the system with
which it is connected.
Plastic. — Capable of being moulded, formed or
modeled.
Plastic Rail-Bond. — A rail-bond on railroads where
sodium amalgam or other conducting substance is
applied in plastic form in order to obtain contact
of rail ends.
ELECTRICAL DICTIONARY 189
Plate Condenser. — A static condenser having a flat
piece of glass for dielectric. Two circular brass
plates mounted on Insulated supports and ar-
ranged to be moved towards or away from each
other ; between them being a plate of glass or other
dielectric, the apparatus being used to illustrate the
principle of the electric condenser.
Plated.^Covered with a metallic coating by the pro-
cess of electro-plating.
Plating. — A word signifying electro-plating.
Plating Dynamo. — A dynamo which furnishes the cur-
rent employed in electro-plating.
Platinoid. — An alloy of copper, nickel, zinc in the pro-
portions of german 'silver with 1 or 2 per cent of
tungsten and useful for its resistive qualities.
Platinum. — A metal of the color of silver with a specific
gravity of 20, which may be increased by heat and
pressure to 21.5. It is heavier than iron, under-
goes no alterations in the air, resists acids, is very
ductile and is the heaviest and least expansible of
the metals.
Platinum Alloy. — Ordinarily an alloy of platinum and
silver.
Platinum Black. — Metallic platinum in the form of a
black powder obtained by decomposing a weak so-
lution of chloride of platinum by the agency of
galvanism, and much used in chemical experi-
ments.
Platinum Fuse. — A slender wire of platinum raised to
incandescence by the passage of an electric current
and used to explode a charge of powder.
Platinum-Iridium Alloy. — An alloy of platinum and iri-
190 ELECTRICAL DICTIONARY
dium valuable for its low temperature-coefficient
of resistance and hence often used for resistance
coils in electrical instruments.
Platinum Lamp. — A lamp equipped with a platinum in-
candescent filament.
Platinum-Silver Alloy. — An alloy of platinum and sil-
ver, one and two parts respectively, and possessing
a low temperature coefficient of resistivity.
Plug Cut-Out. — A cut-out which uses fuse plugs.
Plug Resistances. — Separate resistances introduced into
the circuit by removing plugs. The resistances per-
taining to the common resistance box.
Plugging. — The employment of plugs in completing a
circuit. The making of connections in a switch-
board by introducing plugs into the jacks.
Plunge Battery. — A battery the plates of which are so
arranged as to be immersed in the battery cups or
cells when the battery is to be used and withdrawn
and supported out of the cups or cells when not in
use, thereby obviating waste 'of the plates by stand-
ing in the solution.
Plunger Switch. — A switch whose operating lever cylin-
der is surrounded by a bushing in the switchboard
in order that contacts may be made or broken on
reverse side of board.
Plus Charge. — A positive charge.
Pneumatic. — Pertaining to pneumatics.
Pneumatics. — That branch of science which treats of
the mechanical properties of air and other elastic
fluids.
Pocket Galvanometer. — A galvanometer adapted to
pocket use.
ELECTRICAL DICTIONARY 191
Poggendorff 's Voltaic Cell. — The Grenet cell.
Points of Compass. — The thirty-two points into which
a compass card is divided at equal intervals around
its periphery.
Polar. — Pertaining to a pole.
Polar Bore of Field Frame. — The hollow bored into a
field frame to receive an armature.
Polar Relay. — A relay employed in telegraphy and
which has a normally polarized armature, thus dif-
fering from a neutral relay the condition of whose
armature normally is magnetically neutral.
Polar Surface of Magnet. — The surface of a magnetic
substance through which the magnetic flux passes
in or out. The surfaces either of one or both of a
magnet's poles.
Polar Tips. — An addition made of iron to the field
magnet pole piece of a dynamo-electric machine.
Polarity. — That quality of a body in virtue of which it
exhibits opposite properties in opposite directions.
The possession of poles.
Polarity Indicator. — An instrument employed to indi-
cate the polarity of a magnet or the direction of a
current.
Polarization of Electrolyte. — A supposed arrangement
of molecular assemblage in which the positive poles
of any one assemblage face the negative plate,
whilst their negative poles face the positive plate.
Polarization of Light. — The state of a ray of light in
which the ether-vibrations producing the light are
confined to a single plane; the plane called "plane
of polarization" being perpendicular to it.
192 ELECTRICAL DICTIONARY
Polarization of Voltaic Cell. — An accumulation of gas
— hydrogen usually — on the surface of a voltaic
cell's negative element.
Polarized Armature. — An armature possessing polarity
exclusive of that communicated by the working
current.
Polarized Bell. — An electro-magnetic bell equipped
with a polarized armature.
Polarized Indicator. — An electro-magnetic indicator
provided with a polarized armature.
Polarized Relay. — A telegraphic relay which instead
of having a common soft iron armature is provided
with one permanently magnetized.
Polarizing Current. — A current which causes polar-
ization.
Pole Armature. — An armature whose coils are wound
on separate poles projecting radially all around
the periphery of its central hub or disc, or project-
ing internally from a ring-like frame, their ends
facing the field magnet.
Pole Changer. — An automatic vibrating or oscillating
contact-breaker or switch which, when it moves,
reverses the direction of a current from a battery
or any other current source — whose direction is
fixed — as such current passes through a conductor.
Pole-Pieces of Dynamo or Motor. — The terminations of
the cores of electro-magnets, or of permanent mag-
nets, these terminations having various shapes,
sometimes quite large as compared with the core
proper of the magnet.
Pole Shoe. — An iron or steel plate constituting the pole-
piece of a field magnet upon which it is mounted,
and employed sometimes to support a field coil.
ELECTRICAL DICTIONARY 193
Pole Tips. — (See polar tips.)
Poles of Magnetic Intensity. — The location of highest
magnetic force on the surface of the earth; one
such pole being in Siberia, another in about lati-
tude 52 degrees N., longitude 92 degrees W.
Polishing Bob. — A disc of hard wood having on its pe-
riphery a rim of leather serving when rapidly ro-
tating upon a shaft, and by means of fine emery to
polish articles preparatory to electro-plating.
Polycylic System. — A mutiphase system.
Polyphasal Coupling of Magnetic Circuits. — The inter-
linking of magnetic circuits which are traversed by
polyphase magnetic fluxes.
Polyphase. — Having many phases. Having more than
one phase.
Polyphase Alternator. — An alternator which furnishes
polyphase currents.
Polyphase Apparatus. — Apparatus which is worked by
polyphase currents.
Polyphase Armature. — An armature which is wound in
a manner to produce polyphase currents, or which
is worked by them.
Polyphase Asynchronous Motor. — An asynchronous
motor which is worked by multiphase currents.
Polyphase Currents. — A term signifying groups of al-
ternating currents which constantly differ from
each other by a constant proportion of periods of
alternation, and adapted for operating polyphase
motors.
Polyphase Dynamo. — A polyphase generator.
Polyphase Generator. — An alternator which sends out
194 ELECTRICAL DICTIONARY
alternating currents having a fixed difference in
phase.
Polyphase Inductor-Alternator. — An inductor-alterna-
tor adapted to the production of polyphase cur-
rents.
Polyphase Motor. — A motor driven by polyphase cur-
rents.
Polyphase Synchronous-Motor. — A synchronous motor
driven by polyphase currents.
Polyphotal Arc-Light Regulator. — A regulator adapt-
able for service in series connected arc lamps.
Poncelet. — A term signifying a unit of operative en-
ergy equal to 100 kilogramme-metres per second.
Porcelain. — A fine variety of earthenware valuable for
insulating purposes.
Porcelain Insulator. — An insulator made of porcelain
and used to support a wire.
Porosity. — The quality or state of having pores or inter-
stices.
Porous Cell. — A jar of pipe clay, unglaze^1 earthenware
or other material of like character usod in voltaic
cells to keep two liquids separate and at same time
permit electrolysis and electrolytic induction.
Porret's Phenomenon. — An increase in the diameter of
a nerve produced by the positive pole of a voltaic
circuit m contact with the tissue and in proximity
to the nerve while the other pole is connected to
another part of the body.
Portable Igniting Device. — A portable device employed
for electrically lighting gas or charges of powder
and other explosives used in mining.
ELECTRICAL DICTIONARY 195
Portable Tachometer. — A speed indicator which is port-
able.
Portative Power of Magnet. — The power possessed by a
magnet to sustain a weight by the attraction of its
armature.
Positive Brush of Dynamo. — The brush out of which
passes the current generated in the armature of a
dynamo.
Positive Brush of Motor. — The brush connected with
the positive terminal of an operating source.
Positive Bus-Bars. — Bus-bars connected with a dyna-
mo 's positive terminal.
Positive Carbon. — That carbon contained in a voltaic
arc and which delivers the current into the are.
Positive Currents. — The currents which deflect the
needle to the left, in the single needle telegraph
system.
Positive Electrode. — The electrode which is connected
with the positive pole of a source.
Positive Feeders. — The lead or wire in a set of feeders
which is connected to the positive terminal of the
generator.
Positive Plate of Storage Cell. — A storage cell plate
which by the action of a charging current becomes
coated with a layer of lead peroxide. The plate of
a storage cell which becomes the positive pole of
the cell on discharging by reason of being con-
nected with the positive terminal of a charging
•source.
Positive Plate of Voltaic Cell. — A voltaic couple 's elec-
tro-positive element. The plate, which constitutes
196 ELECTRICAL DICTIONARY
the negative pole of a cell above the surface of the
electrolyte.
Positive Pole. — The north pole in a magnet, or the pole
from which lines of force are assumed to emerge
into the air.
Positive Rotation. — A rotation the motion of which is
from left to right.
Positive Side of Circuit. — The side of a circuit which,
if an observer stood girdled by the current with
his head in the positive side, he would see the cur-
rent pass around him from his right toward his
left hand.
Positive Wire. — The wire connected with the positive
pole of any arrangement or device which will pro-
duce an E. M. F.
Potential Dynamometer. — A device or apparatus adapt-
ed for measuring electric potential differences.
Potential, Electric.— The ability to perform electric
work.
Potential Energy. — The capacity for doing work. Po-
tential chemical energy latent in an elementary
substance which, in combination with some other
element for which it has an affinity, becomes liber-
ated as actual energy for the performance of work.
Potential Galvanometer. — A galvanometer which is
wound with fine German silver wire in order to ob-
tain high resistance and used for determining po-
tential difference.
Potential Gradient. — A line which represents the drop
of potential in a circuit.
Potential Conductors. — The ratio between the volume
of current in a conductor and its capacity. The
ELECTRICAL DICTIONARY 197
property possessed by a conductor to perform elec-
tric work when approached by an electric charge.
Power. — Activity. The rate of activity, of performing
work, or of exerting energy ; the practical unit of
electric power; being the volt, ampere or watt,,
equal to 10 ergs per second.
Power Cable. — A cable through which electric power is
transmitted.
Power Circuits. — Circuits through which electric power
is transmitted.
Power Factor. — The relation, in an alternating-current,
conductor or circuit, of the true watt to the ap-
parent volt amperes.
Power-Factor of Transformer. — The relation, under a
specified load, of the watts taken up by a trans-
former to the watts delivered from the trans-
former.
Power Generator. — An alternating current generator
employed at a telephone exchange.
Power-House. — A house in which the plant of an elec-
tric power system of distribution is located.
Power-Meter. — A watt-meter.
Power-Wire of Monocyclic System. — In a monocyclic
system a wire which furnishes the current to oper-
ate triphase electric motors.
Practical Solenoid. — A term employed to distinguish
the ordinary from the ideal solenoid.
Practical Units. — A system of units based on the abso-
lute system of units, except that multiples of the
original fundamental units of lengths, mass and
time have been taken as the base of the new system,
198 ELECTRICAL DICTIONARY
and they consist of the centimetre-gramme-second
units.
Presbyopic. — Far-sighted.
Pressure, Electric. — Electro-motive force or potential
difference ; an inaccurate term.
Pressure Equalizer. — A device which maintains auto-
matically a uniform pressure, under different loads,
at the terminals of a storage battery. A device used
in a system of electric distribution to regulate the
pressure and keep it uniform.
Pressure Indicator. — An instrument which serves to in-
dicate the electric pressure in a circuit. A volt-
meter.
Pressure Recording-Gauge. — A recording voltmeter. A
recording steam or water gauge.
Pressure Wires. — Copper wires communicating with a
central station from junctions between the feeders
and the mains and serving to indicate at central
station the pressure on the mains.
Primary Battery. — A single electric source comprising
several separate primary cells.
Primary Coil Transformer. — The coil which receives the
current to be transformed.
Primary Currents. — Currents which pass through a pri~
mary circuit.
Primary Cut-Out. — A cut-out used in a primary circuit.
Primary Electric Clock. — A name signifying "control-
ling clock."
Primary Electromotive Force. — Electromotive force ap-
plied to a transformer's primary coil.
Primary Fuse Box. — A fuse box used in a transformer's
primary circuit or in that of an induction coil.
ELECTRICAL DICTIONARY 199
Primary Impedance. — The impedance of a transformer's
primary coil or that of an induction machine.
Primary Plate of Condenser. — The plate of a condensing
transformer which, when containing the inducing
charge, induces in the secondary plate a charge of
different potential.
Prime Magnetic Flux. — Magnetizing force and which
is different from magnetic induction. The flux,
which the prime magneto-motive force produces in
a ferric circuit; and differing from the induced
magneto-motive force.
Prism Error of Compass. — An error occurring in a com-
pass arising from an incorrect disposition of the
prism as referred to the compass card.
Probe, Electric. — A surgeon's probe contrived to indi-
cate by the closing of an electric circuit the pres-
ence of a bullet or any other metallic object in the
human body.
Process of Carbonization. — A method by which suitable
materials are carbonized.
Production of Cold by Electricity. — The reduction of
temperature at a thermo-electric junction attending
the absorption of energy, which follows the passage
of an electric current across the junction in a cer-
tain direction.
Production of Electricity by Light. — Electric difference
of potential effected by the action of light.
Projecting Power of Magnet. — The distance at which
attraction or repulsion is effected by a magnet.
Projection Arc-Lamp. — An arc lamp adopted to pro-
ject for searchlight purposes.
200 ELECTRICAL DICTIONARY
Projector Electric. — A projector at whose focus an elec-
tric arc light is employed.
Projection Armatures. — Armatures in which depressions
are made of sufficient width to leave a projection
in the armature surface, therein differing from the
narrow slotted tunnel armatures.
Prony Brake. — A device used to measure the power ap-
plied to a rotating shaft by applying a clamping
device to the shaft or pulley. A dynamometer.
Proof-Plane. — A small conductor carried at the end of
an insulating handle and used to collect electricity
by contact from objects electrostatically charged,
the charge received being then measured.
Proportional Coils. — Pairs of resistance coils, represent-
ing ordinarily a resistance of 10, 100 and 1,000
ohms each, serving as proportional arms for a
bridge or a balance; used in the box of Wheat-
stone's bridge.
Proposed Definition for 2,000 Candle-Power Arc. — An
arc whose maintenance will require 450 watts.
Propulsion, Electric. — A term signifying propulsion by
electric power.
Protection of Metals, Electric. — A method by which
metals are prevented from corroding, and which
consists of exposing a protecting metal to the cor-
roding fluid, which, by forming with the surround-
ing fluid the positive element of a voltaic couple,
is subjected alone to the corrosive action, and
thereby protects from corrosion any metal with
which it has been placed.
Protection of Ship's Sheathing, Electric. — A method
for preventing the corrosion from water of the cop-
ELECTRICAL DICTIONARY 201
per sheathing of a ship by fastening pieces of zinc
to it.
Protective Sheath. — A sheath of copper introduced be-
tween the primary and secondary circuits of an al-
ternating current transformer, and, being con-
nected to the earth, it becomes grounded if the
primary coil loses its insulation before it can leak
to the secondary, thus protecting the secondary
circuit from the high electro-motive force of the
primary circuit.
Public Supply Instruments. — Electric meters which
serve to register the supply of current to consum-
ers.
Pull. — A switch for closing a circuit when pulled as
distinguished from a push button.
Pulley. — A wheel with a broad rim, mounted on a shaft,
to which the driving power is imparted by means
of a belt.
Pull-Off. — An insulator which serves to hold the trol-
ley wire in its proper place over curves in the
track.
Pulsating Motor. — The early type of motor depending
upon reciprocating motion in its armature as dis-
tinguished from the ordinary rotary motion.
Pulsatory Magnetic-Field. — A field produced by pulsat-
ing currents and by induction; such field can pro-
duce an alternating current.
Pumping of Alternating- Current Dynamo. — A pulsa-
tory movement resulting from imperfect synchron-
ism and observed in synchronously-running alter-
nating current generators or motors.
Pumping of Electric Lights. — A term signifying a pe-
riodical loss or gain in the brilliancy of lights.
202 ELECTRICAL DICTIONARY
Pupillary Photometer. — A photometer whose action is
contingent upon the decrease in diameter of the
pupil of the eye, which is exposed to the intensity
of the light.
Push. — A push button.
Push-Button. — A switch serving to close a circuit by
means of pressure upon a button.
Putting1 Straight. — The restoration to their proper
conditions of wires that have been crossed.
Pyrogravure. — A process of decoration by the means
of a tool, heated electrically or by other means, and
applied to copper, glass or wood.
Pyro-Magnetic Generator or Dynamo. — An apparatus
by means of which electricity is generated directly
from the heat obtained from burning fuel.
Pyro-Magnetic Motor. — A motor operated by the alter-
nation of an armature's or other moving member's
attraction and release, as such member, or section
of it, becomes more or less paramagnetic by heat.
Pyro-Magnetism. — The development, by heat, of new
magnetic properties or alteration of magnetic sen-
sibility in a body.
Pyrometer. — An instrument for measuring tempera-
tures too high for the capacity of thermometers.
Pyrometer, Electric. — An instrument for measuring
high temperatures by the variations in electric
resistance exhibited by a platinum wire exposed to
the heat which is to be measured.
ELECTRICAL DICTIONARY 203
Q.
Quad. — An abbreviation for quadruplex; an abbrevia-
tion for the quadrant, used as the unit of induct-
ance.
Quadrant. — A length, approximately an earth quadrant
and equal to 10.9 centimeters; sometimes applied
to the unit of inductance. The henry.
Quadripolar Dynamo or Generator. — A multipolar
dynamo which has four field magnet poles.
Quadripolar Field. — A field created by four magnet
poles.
Quadruplex Circuit. — A single circuit capable of hav-
ing four messages transmitted over it simultan-
eously, two in one direction and two in the op-
posite.
Quadruplex Telegraphy. — A system of telegraphy pro-
viding for the transmission of messages over a
quadruplex circuit.
Quadruplex Telephony. — The transmission simultan-
eously of four telephonic messages, two in one di-
rection and two in the opposite.
Quadruplex Re-entrant Armature Winding. — An arma-
ture having four separate and independently re-
entrant windings.
Qualitative Analysis. — Analysis for determining the
constituent elements of a compound without regard
to quantity.
Quality of Radiation. — The quality of radiation as re-
ferred only to its frequency and amplitude of vi-
bration.
204 ELECTRICAL DICTIONARY
Quantitative Analysis. — That method of analysis which
determines the proportional quantity of each of
the elements which make up a compound.
Quantity Efficiency of Storage Battery. — The relation
existing between the number of ampere-hours re-
ceived from a storage battery to the number sup-
plied to the battery in charging it.
Quarter-Phase. — The separation by a quarter period of
* two alternating quantities.
Quarter-Phase Armature. — An armature of the poly-
phase class, serving to produce quarter-phase cur-
rents.
Quarter-Phase Bar-Winding for Armature. — A bar-
winding used in a quarter-phase generator's arma-
ture.
Quega. — A prefix meaning a quintillion.
Quick-Break. — A break in a current effected by the
employment of a quick-break switch.
Quick-Break Switch. — A switch by means of which a
circuit is quickly broken.
Quickening Solution. — A solution into which articles
that are to be electro-plated are dipped after clean-
ing immediately prior to their immersion in the
plating bath. A solution of salt of mercury.
Quiet Arc. — An arc devoid of noise.
Quiet Commutation. — Sparkless commutation.
Quivering of Magnetic Field. — The periodic motions of
magnetic flux resulting from the successive com-
mutations of the advancing armature coils and
manifested under the leading pole-piece of a gen-
erator or the trailing pole-piece of a motor.
ELECTRICAL DICTIONARY 205
R.
R. P. M. — An abbreviation meaning revolutions per
minute.
Raceway. — A space along the length of a conduit pro-
vided for the ready introduction or removal of
conductors.
Racing of Dynamo. — Rapid acceleration of speed in a
dynamo-electric machine following the abrupt re-
moval of its load, as, for instance, when a belt
breaks.
Racing of Motor. — Rapid acceleration in the speed of
an electric motor, following the abrupt removal of
its load.
Rack-Rail-Incline Electric Railway. — A method by
which a trolley car is hauled over a steep grade by
means of a rack-rail used as in the ordinary incline
system.
Radial Truck. — A support of a triple-truck design for
the body of a car, the car resting on the end truck
centers in a manner which enables the trucks to
turn freely and carry the middle truck between
them.
Radially-Laminated Armature. — An armature core in
which the iron is made up of light discs, supported
on the shaft in a suitable manner.
Radiate. — To emit or send out in direct lines from a
point or points ; as, to radiate heat.
Radiation Constant. — That heat which is lost by radi-
ation in a given length of time when the tempera-
ture of the body from which the heat is radiated
206
ELECTRICAL DICTIONARY
is one degree higher than that of the surrounding
atmosphere.
Radiation of Magnetic Flux. — The issue of magnetic
flux from a magnet's north seeking pole.
Radiator, Electric. — A radiator electrically heated em-
ployed for heating rooms and other spaces.
Radiograph. — A picture taken by the X-rays process.
Radiometer. — An instrument which comprises four
vanes poised, on an axis, thus enabling it to rotate
freely, and enclosed in a sealed and glass vessel al-
most completely exhausted. The Crookes radio-
meter. t
Radiophonic Sounds.— Sounds produced by the direct
action of radiated energy on certain bodies.
Radophony. — The production of sound by the intermit-
tent action upon a body of a beam of light.
Rail-Bond, Electric. — A device employed to obtain good
electrical contact between the ends of rails in order
to reduce to a minimum the resistance of the joints
of the rails, which are used as a portion of the re-
turn circuit.
Rail Bonding. — Connecting rails in such manner as to
obtain close electric contact.
Railroad, Electric. — An electric railroad, employing
electric motors placed upon cars or locomotives by
means of which they are propelled.
Railway Current-Controller. — A style of switchboard
serving to govern the output of an electric power
house. A motor-controller employed on railroads
to start, stop and modify the speed of cars.
Railway Generator. — A dynamo electric machine em-
ELECTRICAL DICTIONARY 207
ployed in systems of electric railroads to generate
the current required for operation.
Railway Line-Crossing. — Methods adopted to support
trolley wires where two or more cross one another
at points along the line.
Railway Motor. — An electric motor by means of which
electric street and trolley cars are propelled.
Railway Return Circuit. — A grounded circuit used in
trolley systems for ground return. The negative
side of the system usually.
Range Indicating System. — A telegraphic system em-
ployed on men of war whereby the distance of the
targets is determined by the range finder and indi-
cated at the guns.
Rated Candle-Power. — Nominal candle-power.
Ratio Proportionate Arms of Bridge. — A term applied
to the proportionate arms of a Wheatstone bridge.
Ratio of Transformation. — The relation existing be-
tween electromotive force produced at an induc-
tion coil's secondary terminals and that which is
impressed on the primary terminals.
Ray. — A line of light or heat or other form of energy
proceeding from a radiant or reflecting point.
Reactance. — The product of the induction by the angu-
lar velocity of the sinusoidal current which passes
through it. In a simple-harmonic current circuit,
a quantity, the square of which added to the square
of the resistance, gives the square of the impend-
ance.
Reaction Coil. — A coil of high self induction employed
to resist the intensity of, or "choke" alternating
currents, and formed of insulating wire wound
208 ELECTRICAL DICTIONARY
upon a laminated or divided iron core, and so
shaped as to afford a closed magnetic circuit.
Reaction Motor. — Induction motor.
Reaction Principle of Dynamo-Electric Machine. — A
principle of the dynamo current generator provid-
ing for the reciprocal action of the current pro-
duced in the armature coils and the field coils of a
continuous-current dynamo-electric machine,
whereby one strengthens the other until the cur-
rent very soon reaches its full strength.
Reaction Telephone. — A style of telephone equipped
with two coils of insulating wire, one being placed
on the disc and the other on the magnet pole, the
coils reacting upon each other, thus producing a
stronger effect.
Reactive Coil. — Reaction coil.
Reactive Drop. — The drop occurring in a circuit result-
ing from reactance, differing thereby from the drop
due to ohmic resistance.
Real Efficiency of Storage Battery. — In a storage bat-
tery the relation existing between the number of
watt-hours taken out of the battery and those put
into it when charging. The energy efficiency of a
storage battery as distinguished from its quantity
or ampere-hour efficiency.
Rebabbitting. — Renewing the Babbitt metal on ma-
chine bearings.
Recalibration. — The recalibration of an instrument.
Receiver. — An instrument for receiving messages in
telephony and telegraphy and also a term applied
to the receiving instrument of a gramophone and
graphophone.
ELECTRICAL DICTIONARY 209
Receiving End of Line. — The end of a line where the
currents are received as opnosed to the end at
which they are transmitted.
Receiving Magnet. — Any magnet which forms part of
the receiving apparatus employed at the receiving
end of a telegraph or telephone line. A relay.
Receptacle. — A device for the reception of an attach-
ment plug and used in incandescent lighting.
Receptive Device. — A device serving to receive, trans-
late, utilize or transform energy.
Reciprocal. — Quantities which, multiplied together,
produce unity.
Reciprocating Motor. — A motor having a reciprocating
action or one moving first in one direction and then
in the opposite.
Recoil Kick or Disruptive Discharge. — A reaction re-
sulting from a disruptive discharge.
Recorder Ammeter. — An ammeter which makes a per-
manent record of its indications.
Recording Meter. — An electric meter which records its
indications.
Recording Voltmeter. — A voltmeter which makes a per-
manent record of its indications.
Recording Wattmeter. — A wattmeter which records its
indications.
Rectangular Curve. — A curve with outlines approxi-
mately conforming to a rectangular shape.
Rectification of Alcohol, Electric. — The process of recti-
fying or purifying alcohol by electricity.
Rectified. — Commuted — Changed as regards direction.
Rectified Currents. — Commuted Currents.
210 ELECTRICAL DICTIONARY
Rectifier. — A commutator.
Rectifying Commutator. — A commutator that commutes
alternating into direct currents.
"Red" Magnetism. — A distinguishing term suggested
by the two-fluid theory of magnetism and applied
to the magnetism at the north pole of a magnet.
Redressed Currents. — Currents changed, as regards di-
rection or directions by a commutator.
Reduction Gear. — A gear serving to reduce the speed
of a street car below that of its driving motor.
Re-Entrant Armature-Windings. — Armature-windings
which lead back to their point of departure.
Refining Electric. — The electrolytic refining of metals.
Reflect. — To throw back light, heat or the like from a
surface.
Reflecting Galvanometer. — A galvanometer whose
needle deflections are read by means of an image
which a reflected light from a mirror projects. A
mirror galvanometer.
Reflection. — The throwing back of light, heat or the
like from a surface at an equal angle to that at
which it strikes it.
Refract. — To break the natural course of rays in an
elastic medium, as for instance the refraction of
the rays of light as they pass from a rare into a
dense medium.
Refraction. — The change in the direction of a ray of
light, heat or electro-magnetism when it enters
obliquely a medium of a different density from that
through which it has previously moved.
Refractory. — Difficult of fusion. Not readily yielding
to heat ; said especially of metals.
ELECTRICAL DICTIONARY 211
Regenerative Cell. — A cell restored to the performance
of its proper functions of producing currents by a
process of charging.
Registering Photometer. — A photometer which registers
the chemical action of light as distinguished from
one which registers the photometric action.
Regulating Cell for Storage Battery. — A counter-elec-
tromotive force cell.
Regulating Lamp Socket. — A socket provided with a
device having a switch attached and which serves
to vary the brilliancy in an electric incandescent
lamp.
Regulation of Dynamo. — The maintenance of constancy
in the current or pressure of a dynamo by proper
adjustment.
Regulation of Motor. — The maintaining constant of the
speed or the torque, or both, of a motor by proper
adjustment. „
Regulation for Dynamo. — A device serving to regulate
a dynamo.
Regulator for Motor. — A device serving to regulate a
motor.
Regulator Magnet. — A magnet designed to effect any
required regulation automatically. A magnet
whose armature moves in such manner as to auto-
matically shift the commutator brushes to a posi-
tion on the commutator which insures the preser-
vation of the current constant, notwithstanding
any variation of resistance in the external circuit.
Relative Inductivity. — The relation existing between
the inductivity of a medium and that of a vacuum.
Relay. — A telegraphic receiving instrument which
212 ELECTRICAL DICTIONARY
opens and closes a local circuit by movements
caused by the impulses of currents received.
Relay Bells. — Bells connected to a main line by relay
connection for acoustic telegraphy. The system
has practically fallen into disuse.
Relay Contact. — A term often used for a type of electro-
magnetic instrument which serves to complete a
local circuit on the passage of a current.
Relief Photometer. — A form of photometer in which
two divisions of the screen are placed at right
angles to each other and the whole screen then
appearing as a single plane illumined surface, the
quality of illumination is easily determined.
Reluctance. — Magnetic resistance.
Reluctivity. — The reluctance of a cube of matter the
edge of which in length measures one centimeter.
Reluctivity Constants. — Constants which give the reluc-
tivity of iron 'or steel when applied, in accordance
with a formula, to their magnetic force.
Remanent Flux. — Residual magnetism.
Remanent Magnetism. — A term used for residual mag-
netism. The magnetism in a core after the exciting
current ceases to flow.
Repeating Relay. — In telegraphy a relay for repeating
the signals through a second line.
Repeating Sounder. — In telegraphy a sounder which re-
peats a message into another circuit.
Repeating Telegraphic Station. — A Station on a long
telegraphic line occupying a position between the
sections into which the line is divided and at which
the currents received on one section are repeated
into the other section by means of a repeater.
ELECTRICAL DICTIONARY 213
Repeating Telephone Coil. — An induction coil with two
equal windings, each one being connected to a tele-
phone circuit, thus obtaining close inductive asso-
ciation.
Repulsion, Electric. — The tendency 'which exists be-
tween two bodies charged alike, to mutually repel
each other.
Repulsion Motor. — A motor receiving its power through
the mutual repulsion of electric charges. An alter-
nating-current motor receiving its power through
the mutual repulsion of electric charges. An al-
ternating-current motor, in which, by means of a
commutator and brushes, the armature is provided,
for the time being, with short circuited windings.
Residual Atmosphere. — The minute quantity of air or
other gas which is left in a vessel or chamber after
it has been practically exhausted by a pump or
'Otherwise.
Residual Charge. — The charge left in a Leyden jar
after disruptive discharge.
Residual Magnetic-Flux. — The residual magnetism re-
maining after magnetic induction ceases, expressed
in lines of force per square centimeter. Magnetic
flux left in a magnetic circuit after the disappear-
ance of the magnetizing force.
Resilence. — Elasticity.
Resin. — A solid inflammable substance, of vegetable
origin ; a non-conductor of electricity.
Resistance. — That property of an electric conductor by
which it opposes the passage of an electric current.
Resistance Box. — A term applied to a box which con-
tains graduated resistance coils.
214 ELECTRICAL DICTIONARY
Eesistance Bridge.— Electric balance. Wheatstone's
balance.
Resistance Coil. — A coil of wire or other conductor hav-
ing the capacity to offer resistance to the flow of
electricity. A coil of wire employed to measure
an unknown resistance by virtue of its own known
resistance.
Resistance Losses. — Losses caused by friction in the
transmission of energy. Losses in a system of elec-
trical distribution occasioned by resistance.
Resistance of Human Body, Electric. — Ohmic resistance
opposed to the passage of an electric discharge or
current by the human body.
Resistance of Human Skin, Electric. — The ohmic resis-
tance offered by the human skin to the passage of
an electric current.
Resistance of Voltaic Arc. — The resistance which a vol-
taic arc offers to the passage of a current.
Resistance Slide. — A rheostat provided with a sliding
contact by means of which the several resistances
or coils are put in or taken out of a circuit.
Resistants. — Bodies capable of resistance.
Resisting Torque. — The torque required by a motor to
enable it to move. The torque of retarding forces.
Resonator, Electric. — An open electric circuit of small
dimensions whose ends are nearly in contact and
which, when subjected to the influence of the elec-
tric resonance, a spark produced by the inductance
of the resonator passes across the gap.
Rest. — A cessation from motion.
Resultant. — A force which is the joint effect of two or
more forces.
ELECTRICAL DICTIONARY 215
Resultant Induction. — The magnetic induction in a
dynamo 's armature or any mass of magnetized ma-
terial which is the resultant of the inducing effect
of several components of magnetic induction.
Resultant Magnetic Field of Dynamo. — The magnetic
field which is the product of both the field pro-
duced by the field magnets and the current passing
through the armature coils.
Retardance. — The limitation of a telephone circuit with
respect to the transmission of sound and which is
equal to the total ohmic resistance and total ca-
pacity of the line.
Retarding Coil. — Choking Coil.
Retarding Disc. — A disc of copper mounted on a rotat-
ing shaft so arranged as to cut magnetic flux, which
results in the retardation of its rotary speed.
Retardation Coil. — Choking Coil. Retarding coil. In-
duction coil.
Retentiveness. — That property which enables steel to
retain its magnetism.
Retentivity. — The quality of retaining magnetization
or of resisting demagnetization.
Retort Carbon. — Carbon deposited from decomposition
of the hydrocarbons and little used for electric
purposes owing to its extreme hardness.
Return Circuit. — That portion of a circuit by which
an electric current returns to the generator.
Return Feeders. — The feeders along which the current
passes on its way back to a central station. The
return feeders on a trolley line which are connected
with the track. Ground feeders. Negative feed-
ers.
216 ELECTRICAL DICTIONARY
Return Ground. — The portion of the ground which
serves as a return. The ground-return.
Return-Signal Call-Box. — A call-box which answers a
signal.
Reversal. — A change of direction.
Reversal of Phase. — A change in the phase of a current
which is caused either by the reversal of the cur-
rent or of the conductor in which it is generated.
Reversible Electric Motor. — A motor, the direction of
whose motion can be easily reversed. A motor
constructed in a manner to render its operation as
a generator practicable.
Reversibility of Dynamo. — A dynamo, which when
traversed by an electric current, can operate as a
motor.
Reversing. — To alter a direction to its opposite.
Reversing a Current. — Altering a current's direction.
Reversing Controlling-Box. — A controlling box by
means of which the direction of a motor's rotation
can be reversed.
Reversing-Gear of Electric Motor. — Apparatus by
means of which a motor's direction of rotation can
be reversed.
Reversing-Handle of Car Controller. — A switch handle
attached to a car controller and serving to change
its direction of motion. The handle of the emer-
gency switch.
Reversing Key. — A key which, when inserted in the cir-
cuit of a galvanometer, obtains deflections on either
side of its scale. A key whose function is, when
inserted, to reverse the current given out to a cir-
cuit.
ELECTRICAL DICTIONARY 217
Rheostat. — An apparatus serving to change the resist-
ance without opening a circuit. An adjustable re-
sistance.
Rheostat Frame. — A perforated frame in which the sev-
eral resistances of a rheostat are enclosed.
Rheostat Panel. — A switchboard panel to which the cir-
cuits of the rheostat are connected.
Rhumbs of Compass. — The points of the compass.
Ribbon Conductor. — A conductor resembling a ribbon
in shape.
Ribbon Copper. — A copper conductor resembling a rib-
bon in shape.
Right-^Handed Armature Winding. — A dextrorsal wind-
ing of an armature core.
Right-Handed Dynamo. — A dynamo which rotates
right-handedly when observed from the pulley end.
Right-Handed Helix. — A helix on which the convolu-
tions of wire are wound in a right-handed direc-
tion— in a clock-wise direction.
Right-Handed Motor.— A motor designed to run in a
direction, when viewed from the pulley end, corre-
sponding to the direction followed by the hands of
a clock.
Right-Handed Solenoid. — A right-handedly wound
solenoid.
Ring Armature. — An armature whose core is ring-
shaped.
Ring Clutch. — A clutch, ring-shaped, and serving to
clutch the lamp-rod of an arc lamp when the ring
gets out of horizontal position.
Ring Clutch for Arc Lamp. — A clutch resembling a ring
in shape, and which encircles the lamp rod, holding
218 ELECTRICAL DICTIONARY
it firmly when in an inclined position, but allowing
it to drop when in a horizontal position.
Ring-Connected Generator. — A generator whose arma-
ture is wound in such a manner as to provide for
the connection of corresponding points to ring con-
ductors, thereby equalizing the current distribu-
tion and flux around the armature.
Ring-Magnet. — A bar evenly magnetized and made into
a ring.
Ring-Off. — A term applied to the signal given by a sub-
scriber when he has finished using the telephone.
Risers. — "Wires which run vertically from floor to floor
in a building in order to furnish the different floors
with current from the service wires.
River Cable. — A sub-aqueous cable adapted for use in
•rivers.
Riveted Railway- Joint. — A rail-joint effected between
two rails by means of heavy fish plates, riveted to
the end of each rail.
Roaring of Arc. — A roaring noise accompanying the
formation of a strong voltaic arc and due to too
close proximity of carbons.
Rocker Arms. — Arms projecting from a rocker and
each one carrying one of the brush holders.
Rocker-Arm Circle. — The movable piece mounted con-
centrically with the commutator and carrying the
rocker arms and brush holders, and which, by
being moved, adjusts the brushes for proper lead.
Rod-Clamp. — A clamp used in the lamp rod of an arc
lamp.
Rod Clutch. — A device serving to clutch the carbon
rod in an arc lamp.
ELECTRICAL. DICTIONARY 219
Roentgen Effects. — Effects obtained by means of the
Roentgen or X-rays.
Roentgen Radiograph. — A term proposed for radio-
graph.
Roentgen-Ray Screen. — A screen whose surface is cov-
ered with fluorescent material for the purpose of
receiving and displaying a Roentgen image.
Roentgen-Ray Transformer. — A transformer of alter-
nating current and adaptable for operating a
Roentgen-ray tube.
Roentgen-Ray Tube. — A glass vessel containing a high
vacuum and sealed hermetically with electrodes
passing through it.
Roentgen Rays. — A peculiar form of radiation discov-
ered by Roentgen, and which is emitted from that
portion of a high vacuum tube upon which the
cathode rays fall.
Roget's Spiral. — A cylindrical helix of wire suspended
by one end, the other end dipping into a mercury
cup, an active circuit being connected, one termi-
nal to the upper end, the other to the mercury cup,
thus bringing the apparatus in- series into the cir-
cuit, while the current as it flows causes the coil
to shorten, each spiral attracting its neighbor ; thus
breaking the circuit by the lower end being drawn
out of the mercury cup; and when the current is
cut off the coils do not attract each other, and the
ends drop into the mercury cup again, and in this
way the circuit is alternately opened and closed.
An automatic contact breaker.
Rosette. — An ornamental device placed in a wall or
ceiling and equipped with service wires in order
220 ELECTRICAL DICTIONARY
that an electric lamp or an electrolier may be easily
attached.
Rosette Cut-Out. — A rosette having a cut-out.
Rotary Converter. — A motor and dynamo combined
whose function is to transform a current of any
kind — high or low voltage, alternating or con-
tinuous— into any other kind of current desired ;
the watts taken in being in excess of those put out.
Rotary Current. — A term used signifying polyphase
currents which can produce a rotary field.
Rotary-Field Induction Motor. — An induction motor
which is operated by causing the field coils to be
excited one after another successively around the
periphery of the armature.
Rotary-Magnetic Field. — A field resulting from a rotary
current ; a magnetic field.
Rotary Magnetism. — Magnetism which a rotary mag-
netic field produces.
Rotating Brushes of Dynamo.— Discs of metal which
rotate around the periphery of a commutator there-
by translating the current, and used sometimes in-
stead of the ordinary brushes.
Rotating Current. — A term signifying the current
which is the product of a combination of alternat-
ing currents, the phases of which are definitely dis-
placed as referred to one another; a multiphase
current.
Rotating-Current Transformer. — Rotary-current trans-
former.
Rotor. — The rotating part of an induction alternating
electric machine.
Rubber Tape. — A rubber insulating adhesive tape.
ELECTRICAL DICTIONARY 221
Ruhmkorff Coil. — A common induction coil with circuit
breaker, used with constant and direct current. A
coil in which a high voltage is induced in the sec-
ondary coil. A step up transformer with a circuit
breaking attachment.
Bumble. — A hollow cylinder into which are placed
small articles that are to be polished preparatory
to electro-plating, the cylinder being rotated by
mechanical power, the articles are kept in constant
motion, and the desired effect is obtained by their
attrition against one another or against other hard
objects which may be contained in the cylinder for
that purpose.
Running Position of Street-Car Controller. — The posi-
tion of the switch handle while the current which
keeps the motors in rotation is being supplied, and
a position differing from that maintained while the
current is cut off.
Running Torque of Motor. — The torque which a motor
exerts while running, and to be distinguished from
the starting torque.
S.
S. P. Cut-Out. — An abbreviation meaning single pole
cut-out.
Safe Carrying Capacity of a Conductor. — The strength
of current which a conductor will carry without
overheating.
Safety-Catch.— Safety fuse.
Safety-Catch Holder. — Safety fuse holder.
Safety Device for Arc Lamps or Series Circuit. — An
222 ELECTRICAL DICTIONARY
automatic device by the operation of which a path
for a current around a lamp or other defective de-
vice in a series circuit is made, thereby obviating
the opening of a whole circuit.
Safety Fuse. — A wire or any other suitable form of
metal which is easily fusible and capable of carry-
ing an ordinary current without fusing, but which
will fuse under an unusually strong current and
automatically break the circuit.
Safety Fuse-Block. — A block serving to receive a safety
iuse.
Sag of Conductor or Line Wire. — The sag of an over-
head wire or conductor suspended between two
points of support.
Salimeter. — A hydrometer by means of which the den-
sity of saline solutions is measured.
Saline Creeping. — A deposit of salts on the walls of
solids immersed in saline solutions, effected by
efflorescence.
Saline Solution. — A salt dissolved in a liquid.
Sand-Box for Electric Car. — A box containing sand and
attached to a car for the purpose of sprinkling the
sand over the track, thereby increasing the friction
between the wheels and the rails.
Saturated Solution. — A solution which has dissolved as
much of a solid as it is capable of dissolving at a
given temperature.
Sayers Armature Winding. — An armature winding de-
signed to obtain sparkless commutation by means
of additional coils, termed commutator coils, which
are exposed to the action of an auxiliary pole and
introduced into the main circuit.
ELECTRICAL DICTIONARY 223
Scale Zero. — An instrument zero.
Scarf Joint of Conductors. — A joint effected between
the ends of conductors by cutting the ends on a
bias and then soldering them together, thereby
preserving a cylindrical shape and smooth surface.
Sciagraph. — A name proposed for radiograph.
Scintillating Jar. — A Leyden jar the coatings of which
are made by placing small pieces of tin-foil on the
glass at certain distances apart, leaving small
spaces between them.
Scratch Brush. — A brush of wires or stiff bristles serv-
ing to remove all foreign matter from the surface
of metallic articles preparatory to electro-plating.
Screen, Electric. — A cage, plate or hollow case com-
posed of a conducting substance and having an
earth connection so as to protect from electrostatic
influences any object placed inside of it.
Screening Effect of Eddy Currents. — The effect which
eddy currents cause in a solid body of iron or steel,
and which consists in protecting the interior of the
body from the influence of an external alternating
magnetic field.
Sea Cell Test. — A circuit test used in submarine electric
torpedo work and accomplished by means of a
single voltaic cell, the sea water serving as the elec-
trolyte.
Seal of Meter — A seal of lead put on a meter to guard
against tampering with the meter after it has been
set.
Sealing-In of Filament. — The hermetical sealing of an
incandescent lamp between the support of the fila-
ment and the lamp chamber.
224 ELECTRICAL DICTIONARY
Sealing-Off of Lamp Chamber. — The hermetical sealing
of a lamp chamber by fusing the glass w^iile the
lamp is still connected with the pumps.
Search-light, Electric. — An apparatus which produces
a powerful stream of light and projects it in any
direction, employing a focusing -arc lamp, which,
provided with large carbons, is enabled to use a
heavy current; and the lamp is so situated as to
project the greater part of the light onto a suitable
reflector or lens, thereby concentrating the rays
into one immense beam.
Secondary. — A term applied to the secondary coil of a
transformer or induction coil.
Secondary Ampere Turns. — The ampere turns in the
secondary coil of an induction coil or transformer.
Secondary Battery! — A storage battery.
Secondary Cell. — A storage cell.
Secondary Clock. — A clock in a system of time teleg-
raphy, whose movements are controlled by the cur-
rent, regulated by the master clock.
Secondary Coil of Transformer. — A transformer's coil
which receives energy from the primary coil. The
secondary winding of an induction coil or trans-
former.
Secondary Currents. — Currents produced in a conduc-
tor by changes in currents in a contiguous conduc-
tor. The currents produced in the secondary cir-
cuit of an induction coil or alternating current
converter.
Secondary Fuse-Box. — A fuse-box placed in a transfor-
mer's secondary circuit or in that of an induction
coil.
ELECTRICAL DICTIONARY 225
Secondary Plate of Condenser. — The plate of a con-
denser which becomes charged by reason of the ex-
istence of a charge in the opposite plate.
Secret Telephone System. — A telephone system ope-
rated independent of an exchange or an attendant
and arranged in such a manner as to enable per-
sons to communicate with each other between any
two stations without being heard by any other per-
son on the line.
Section. — The intersection of two superficies, or of a
superficies and a solid; in the former case a line,
in the latter a surface. A length of conductor in-
sulated from contiguous portions, as observable in
trolley systems.
Section Circuit-Breaker. — A magnetic circuit-breaker
by which a trolley wire section is controlled.
See-Sawing. — A term which describes the improper
synchronization of two parallel connected alter-
nators.
See-Sawing of Parallel Connected Generator. — Im-
proper synchronization existing between gene-
rators.
Segment Switch. — A switch in which an arm is pivoted
in such a manner as to enable it to describe in its
movement the arc of a circle, which is divided into
insulated segments.
Selectance. — A quality possessed by resonant electric
circuits and by virtue of which they respond to
one frequency of alternating current more than to
another.
Selective Absorption. — A selected character of absorp-
tion of the waves of light, heat, electricity or
sound.
226 ELECTRICAL DICTIONARY
Selective Consonance. — A quality possessed by a con-
sonant alternating current circuit by virtue of
which it responds to one frequency more than to
another.
Selective Resonance. — That quality possessed by a reso-
nant circuit and by virtue of which it becomes
selective to a definite frequency of alternating cur-
rent.
Selective-Signal Pendulum. — A system of selective sig-
naling wherein the receiving bells are each actu-
ated by a single alternating current frequency, and
the transmitting frequency is adjusted to agree by
changing the length of a pendulum in the trans-
mitter.
Selective Signaling Apparatus. — Individual signaling
apparatus.
Selenium. — An elementary substance allied to sulphur,
its resistance being very susceptible to the action
of light.
Selenium Eye. — A crude imitation of the human eye in
which the eyelids are represented by two slides
and selenium resistance represents a retina.
Selenium Photometer. — A photometer determining by
comparison the intensity of light; the means of
comparison being the changes in the resistance of
a selenium resistance by successive exposures
under like conditions first to the light to be meas-
ured, then to a standard light.
Selenium Resistance. — A resistance demonstrated by
means of a mass of selenium which, when exposed
to the light, experiences a variation of value cor-
responding to the variations in the intensity of
the light.
ELECTRICAL DICTIONARY 227
Self -Acting Make-and-Break. — An automatic make-and-
break device.
Self -Aligning Bearings. — Bearings for journals which
are devised and adjusted in such a manner as to
allow to a small extent an angular movement,
which enables them to conform to the surface of
the shaft.
Self-Cleaning Contact Key. — A term applied to a key
which has a rubbing contact.
Self-Contained Engine or Machine. — An engine or ma-
chine containing within itself all its working parts
supported on a single solid foundation.
Self -Excitation. — An excitation of a generator's field
magnets by the passage of its own current through
its own field coils.
Self-Excited. — Excited by its own current.
Self-Excited Alternator. — An alternator the fields of
which are self-excited.
Self-Excited Dynamo. — A dynamo the field of which
is self-excited.
Self-Excited Series-Wound Continuous-Current Gen-
erator.— A continuous-current generator with a
series-wound field, whose excitation is due to the
current from the generator's own armature.
Self-Excited Shunt-Wound Continuous- Current Gen-
erator.— A continuous-current generator with a
shunt-wound field, whose excitation is produced by
some of the current diverted in its passage from
the armature to the external circuit.
Self-Induced Current. — A current which is induced in
a circuit by alterations in its own strength attend-
ing the opening or the closing of a circuit.
228 ELECTRICAL DICTIONARY
Self-Oiling Bearings. — Bearings employing automatic
oilers.
Self -Oiling Journal. — A journal employing automatic
oilers.
Self-Registering Tachometer. — A tachometer whose in-
dications of the different speeds of a machine are
permanent.
Self -Regulating Dynamo. — A self -regulating generator.
Self-Regulating Generator. — A generator which, by
reason of the manner in which it is wound, main-
tains automatically, notwithstanding any change
in the resistance of its load, either a constant-cur-
rent in the circuit or a constant difference of po-
tential.
Self-Regulating X-Ray Tube.— An X-ray tube which
is capable of automatically adjusting the degree
of vacuum and controlling consequently the elec-
tric pressure at the terminals.
Self -Starting Alternating-Current Motor. — An alternat-
ing current-motor provided with the means which
enable it to start with any normal load.
Self-Winding Clock. — A clock which automatically
winds itself by means of a small electro-magnetic
motor which obtains its current from one or sev-
eral voltaic cells, the whole apparatus being in-
closed within the clock's case.
Semaphore. — An apparatus for exhibiting signals and
used in the railroad block system.
Semaphore Arm. — An arm of a semaphore capable of
being moved about to exhibit the signals which
indicate the condition of the block sections with
respect to trains.
ELECTRICAL DICTIONARY 229
Semi-Circular. — Pertaining to a semi-circle.
Semi-Period. — A half period; the time consumed by a
reversal.
Sensibility of a Galvanometer. — The degree to which
the needle of the galvanometer is affected in its de-
flections by an electric current passing through its
coils. The deflection which a definite small current
strength causes.
Sensitive Telephone. — A telephone which is capable of
performing its functions with less current than
that which is usually required in telephone opera-
tion.
Sensitive Tube. — A coherer.
Separable Iron Core. — An iron core capable of being
separated from the machine of which it is an ac-
cessory.
Separate Circuit Dynamo. — A dynamo which is able to
furnish the current to a number of separate cir-
cuits. A form of self-exciting dynamo.
Separate-Coil Machine. — A machine the armature coils
of which are separated from each other mechani-
cally and not interlaced as in another form of ma-
chine.
Separate Excitation. — A dynamo-electric machine
whose field magnets are excited by a separate .coil
or winding in the armature put there for that pur-
pose.
Separately-Excited Alternator. — The excitation of the
field magnets, effected by external influence.
Separately-Excited Dynamo-Electric Machine. — A dy-
namo-electric machine the field coils of which are
excited separately.
230 ELECTRICAL DICTIONARY
Separately-Excited Field. — The field of a dynamo sup-
plied with its magnetizing current by a source out-
side.
Series and Magneto Dynamo-Electric Machine. — A
dynamo compound wound, in which the find wind-
ing on the field magnets is excited by the armature
of a magneto-electric machine with which it is con-
nected.
Series-and-Separately-Excited Dynamo-Electric Ma-
chine.— A compound-wound dynamo which pro-
vides for a winding of its field magnet cores with
two distinct circuits, one core forming a connec-
tion with the field magnets and outside circuit
in series, while the other forms a connection with
some other source, which causes its individual ex-
citation.
Series-and-Shunt- Wound-Dynamo-Electric Machine. — A
compound-wound dynamo whose winding of field
magnets consists of two distinct coils, one of which
is wound with the armature and outside circuit,
in series, while the other is wound in shunt with
the armature.
Series-Arc Cut-Out. — A contrivance by means of which
a short circuit past a defective lamp in a series-con-
nected circuit is automatically secured, which pro-
vides for the undisturbed operation of all the other
lamps in case of the failure of any one.
Series Circuit. — A circuit established by an arrange-
ment of the separate sources and electro-receptive
devices, which provides that the current produced
in the circuit shall pass successively through the
entire circuit.
ELECTRICAL DICTIONARY 231
Series-Connected Battery. — A battery consisting of
series-connected cells.
Series-Connected Incandescent Lamps. — Lamps which
are connected to a circuit in series, a cut-out of
some description being employed, so that in the
event one lamp should be extinguished the others
would continue their efficient operation.
Series-Connected Electro-Receptive Devices. — Electro-
receptive devices connected in series to a circuit
Series-Connected Sources. — Separate sources, acting as
single sources, due to the manner in which they
are connected in series.
Series-Connected Translating Devices. — Series-con-
nected electro-receptive devices.
Series-Connected Voltaic Cells. — Voltaic cells which
possess the ability to act as a single source by
reason of the manner in which they are connected
in series.
Series Connection. — A number of distinct electric
sources, electro-receptive devices, or circuits, con-
nected in such manner as to obtain a passage of
the current from first to last in the circuit suc-
cessively.
Series Distribution. — A distribution of electricity in
which the receptive devices are arranged in suc-
cessive order upon one conductor extending the
entire length of the circuit.
Series Dynamo. — A series-wound dynamo.
Series Field-Terminals of Motor. — Terminals of a com-
pound-wound motor with which the ends of a se-
ries field winding are connected.
232 ELECTRICAL, DICTIONARY
Series Incandescent Lamp.— An incandescent lamp
adaptable for service in a series circuit.
Series Incandescent Lighting System. — A system of in-
candescent lighting differing from the multiple sys-
tem in the manner of connecting; the former sys-
tem having its lamps connected in series, while in
the latter they are connected in parallel.
Series Motor. — A motor adaptable for use in a series
circuit. A motor whose field coil winding is in se-
ries with the armature.
Series-Multiple. — A series-multiple connection.
Series-Multiple-Controller. — A controller designed for
a double motor car and which operates by connect-
ing the motors either in series or in parallel, with or
without resistance, its function being to stop, start,
vary the speed of the car or vary the torque of
the motors.
Series-Multiple Circuit. — A compound circuit where a
number of separate groups composed of distinct
sources or electro devices, or both, connected in
groups in multiple arc, are afterwards connected
in series.
Series-Multiple-Connected Sources. — A single source
formed by the connection of a number of distinct
electric sources, and in this single source the dis-
tinct sources are connected in a number of dis-
tinct multiple circuits, and these circuits are con-
nected together in series separately.
Series-Parallel Controller. — A series multiple controller.
Series-Winding. — A method of winding a generator or
motor, in which one of the commutator-brush con-
nections is connected to the field magnet winding,
the other end of the magnet winding being con-
ELECTRICAL DICTIONARY 233
nected with the outer circuit, and the other arma-
ture brush being connected with the other terminal
of the outer circuit.
Service Block. — A block serving to support and con*
nect service wires.
Service Wires. — Wires connected to the supply circuit
or main and which run into a building or structure
to supply the current.
Sextipolar. — Having six poles.
Sextipolar Dynamo.— A dynamo with a sextipolar field.
Sextipolar Field* — A field created by six magnet poles.
Shadow Photometer. — A photometer in which the rela-
tive intensity of the two lights is estimated by the
intensity or strength of the shadows of the same
object which they respectively cast.
Shear. — A stress consisting of a lateral projection com-
bined with an equal perpendicular compression.
Shearing Stress. — A stress causing a shear.
Sheathing a Cable. — The covering which is used to pro-
tect a cable.
Sheathing Wires. — The wires which are used for the
armor of a submarine cable.
Shell of Commutator. — A commutator core apart from
the shaft.
Shell Transformer. — A transformer having its primary
and secondary coils placed one upon the other, and
they are entirely inclosed by the iron core which
is wound through and over them.
Shellac. — A vegetable substance of a resinous nature
obtained from the juices of certain tropical plants
and valuable for its superior insulating qualities
and inductive capacity.
234 ELECTRICAL DICTIONARY
Shifting Magnetic Field. — A magnetic field which ro-
tates, its lines of magnetic force varying in posi-
tion as referred to the magnet pole which emits
them.
Shifting Zero. — A zero which changes its position.
Ship Dynamometer. — A dynamometer which serves to
indicate the strain on a grappling cable and used
on cable ships.
Shock. — A sudden striking agaftist ; a collision ; a sharp
concussion of one thing against another; the vio-
lent agitation of the nervous system.
Shock, Electric. — -The sudden convulsion of the mus-
cles, with a feeling of pain, occasioned by an elec-
tric discharge through the animal system.
Shoe of Contact for Street Railway. — A metallic cast-
ing employed on street railroads in connection with
a rail-brake and serving to stop the car by the re-
sistance offered, due to its friction upon the rail.
Short Arc System of Electric Lighting. — A system of
lighting effected by short voltaic arcs between car-
bon electrodes.
Short Circuit. — A connection between two parts of a
circuit, which connection is a low resistance com-
pared to the intercepted portion; a shunt or by-
path. A term used also as a verb, as "to short
circuit a lamp"; "to cut out of circuit by a short
conductor. ' '
Short-Circuited Conductor.— A conductor having a
short circuit connected past it.
Short-Circuiting a Dynamo-Electric Machine. — Employ-
ing a short circuit to cut out the outer circuit of
a dynamo. Connecting the poles of a dynamo by
a circuit of low resistance.
ELECTRICAL DICTIONARY 235
Short-Sightedness. — A defect in the eye which causes
objects to appear indistinct when not near to the
eye, and which is caused by abnormal convexity
of the eyeball.
Shunt. — A connection in parallel with a portion of the
circuit in a current circuit.
Shunt. — To establish a connection in parallel with a
portion of the circuit.
Shunt-Breaking Resistance. — A resistance employed in
a field of a shunt dynamo, so that when breaking
its circuit the danger of producing excessive in-
duced pressure may be obviated.
Shunt- Circuit. — A subsidiary circuit in any part of a
circuit where the current divides, some of it flow-
ing in the main circuit and some of it through the
subsidiary or shunt. A partial circuit connected
to two points of another circuit and running par-
allel with it between the two points.
Shunt-Coil. — A coil in a shunt circuit.
Shunt Dynamo. — A shunt-wound dynamo.
Shunt-Field Terminals of Motor. — The terminals of an
electric motor's shunt-field coils.
Shunt for Ammeter. — A shunt coil serving to change
the value of the readings of an ammeter and which
is connected in multiple with the coils thereof.
Shunt-Rheostat. — A rheostat in a shunt-circuit.
Shunt Turns of Dynamo. — In a shunt-wound or com-
pound-wound dynamo shunt turns signify the am-
pere turns.
Shunt-Winding. — The winding of a dynamo in which
the field magnet winding is in shunt or parallel
with the winding of the armature.
236 ELECTRICAL DICTIONARY
Shunt-Wound Dynamo-Electric Machine. — A dynamo
electric machine whose commutator brushes have
two connections, one set being the terminals of the
outer circuit, while the other set are the terminals
of the field magnet windings; or, in other terms,
the field magnet windings are in shunt or in par-
allel with the outer circuit.
Shunt-Wound Motor. — A motor the field magnet coils
of which are connected in shunt to the armature
circuit.
Shunted. — Having a shunt.
Shuttle Armature. — The original Siemans' armature,
now in disuse. A form of drum armature having
a long, narrow core and its cross section cor-
responding nearly to the form of an H, the grooves
of which are wound full of wire, so that the whole
forms almost a perfect cylinder.
Side-Bar Suspension of Motor. — The employment of two
light rods mounted on springs, which are parallel
to the side frames, for the purpose of supporting
the motors in a street railway car truck.
Side Commutator. — The commutator of a dynamo-elec-
tric machine which is set on the side of the revolv-
ing armature.
Side of Three- Wire System. — In the three-wire system
of distribution a term used signifying the positive
or negative conductor.
Side Suspension of Motor. — The suspension of motor
by means of side bars.
Sides of Three-Wire System. — Those parts of the three-
wire system having positive and negative poten-
tials respectively.
ELECTRICAL DICTIONARY 237
Siemens Electro-Pyrometer. — An instrument for the
determination of temperatures by the variations in
electric resistance in a platinum wire exposed to
the heat which is to be measured.
Signal-Service System for Electric Railroads. — A sys-
tem of electric signals in use on railroads for ob-
taining information pertaining to the operation of
the road, the giving of instructions to trainmen and
others and for general communication from sta-
tions to trains.
Sight Feeding Oiler. — An oil cup made of glass, by
means of which the feeding of oil can be observed.
Silver Bath. — A solution of a salt of silver for deposi-
tion in the electro-plating process. An electrolytic
bath containing a solution of a salt of silver, with
a plate of silver immersed in it and serving as the
anode; the article to be plated serving as the
cathode.
Silver-Palladium Alloy. — An alloy of silver palladium
and other metals, valuable for its non-magnetic
properties and much used for certain parts in the
works of watches.
Silver-Plating. — Depositing a coat of silver upon the
surfaces of base metals by the process of electro-
plating.
Simple Arc. — A voltaic arc produced between only two
electrodes.
Simple Circuit. — A circuit having a single generator
and a single receiver, such, for instance, as a motor
or sounder with a single connecting conductor.
Simple-Harmonic Currents. — Currents with a variable
flow in strength and duration; a simple harmonic
curve serving to represent the quantity of elec-
238 ELECTRICAL DICTIONARY
tricity passing by any section of conductor. Such
a character of current that a simple harmonic curve
may express the continuous variation of the flow
past any area of cross-section of the conductor, or
the continuous variations in electro-motive force.
Simple-Harmonic Curve. — The curve which results
when a simple-harmonic motion in one line is com-
pounded with uniform motion in a straight line at
right angles thereto.
Simple-Harmonic Motion. — Motion of a point back and
forth along a line; the motion of a pendulum, as
regards its successive swings back and forth, is
an example of harmonic motion. Simple-periodic
motion.
Simple Immersion. — -Electro-plating without a battery
and by simply immersing the metal in a solution
of metallic salt.
Simple Magnet. — A magnet made of one piece of metal.
Simple Shunt. — A coil designed as a shunt; having no
iron core.
Simplex Telegraphy. — -A system of telegraphy provid-
ing for the transmission of a single message only
over the line wire.
Sine Galvanometer. — A galvanometer whose measure-
ments are contingent upon the sine of the angle
of deflection produced when the coil and needle
rest in the one vertical plane.
Single Brush-Rocker Arm.- — An arm holding a single
pair of brushes in such a position on a dynamo or
motor as to enable them to be shifted easily into
the required position on the commutator.
Single-Contact Carbon Telephone. — A style of telephone
transmitter with a single contact.
ELECTRICAL, DICTIONARY 239
Single-Coil Field Dynamo. — A dynamo with a magnetic
field which, is produced by a single magnetizing
coil.
Single Field-Coil Multipolar Dynamo. — A multipolar
dynamo provided with a single field-coil on a single
core, and having a number of polar projections.
Single-Fluid Hypothesis of Electricity. — A hypothesis
which attributes electrical phenomena to the pres-
ence or absence of a single fluid.
Single-Loop Armature. — An armature provided with a
closed conducting circuit, with a single loop, and
situated in such a manner as to enable it to revolve
in a magnetic field and cut its magnetic flux.
Single-Magnet Dynamo-Electric Machine. — A single
field-coil dynamo.
Single-Pair Brush Yoke. — A device for holding a single
pair of brushes on a dynamo so as to enable them
to be shifted easily in the required position on the
commutator.
Single Phase. — A phase characterizing that which is
present in ordinary alternating currents in a simple
alternating current system; being uniphase or
monophase differs in this respect from multiphase
currents.
Single-Phase Motor. — A monophase motor.
Single-Phase Induction Motor. — An induction motor
which is designed to operate on a uniphase alter-
nating current circuit.
Single Phase Synchronous Motor. — A synchronous
motor which can be operated by monophase
currents.
240 ELECTRICAL DICTIONARY
Single-Phase Transformer. — A transformer designed
to supply or transform uniphase currents.
Single-Pole Cut-Out. — A cut-out which breaks the cir-
cuit or cuts in only one lead.
Single-Pole Switch. — A switch employed to open or
close at only one lead.
Single-Pole Telephone Receiver. — A telephone receiver
having but one pole presented to the diaphragm,
and in this respect differing from a receiver where-
in two poles, each inclosed within a coil, are pre-
sented to the diaphragm.
Single-Reduction. — Speed-reducing by a single gear
wheel only. A gearing through the medium of
which a single reduction of speed is effected as dis-
tinguished from a double gearing in which two
separate reductions are effected.
Single-Reduction Street-Car Motor. — A street-car motor
whose car-axle motion is reduced by means of a
single reduction gear, connected with the car axle,
as distinguished from a motor which is geared,
through two successive gear wheels, with the car
axle.
Single-Stroke Electric Bell. — An electric bell which
only strikes once each time the circuit is closed.
Single-Throw Switch. — A switch which, in opening and
closing a circuit, assumes two positions only.
Single-Trolley System. — A trolley system employing
only one overhead conducting wire, .the track and
ground serving as a return.
Single-Truck Car. — A car whose body is borne on a
single truck.
Single-Wire Multiple Telephone Switchboard. — A
ELECTRICAL DICTIONARY 241
switchboard having the jacks all in series in each
line and serving to connect ground-return sub-
scribers' lines. A single-cord multiple switch-
board employed in telephone service.
Single-Wound Gramme Ring. — A gramme ring having
a single winding, in which the number of coils
is a. multiple of the number of poles, and the num-
ber of commutator segments equals the number of
poles.
Single-Wound Multiple-Circuit Multipolar Drum-Arma-
ture.— A drum-armature so wound as to obtain a
multipolar field in a single winding and afford a
number of paths between the brushes.
Single- Wound Two- Circuit Drum- Armature, — A drum-
armature wound for a multipolar field, with a sin-
gle winding, and which provides for two circuits or
paths between the circuit.
Single-Wound Two-Circuit Multipolai ftijig- Armature.
— A ring armature so wound £s 6C obtain a multi-
polar field, with a single wind ;ag, and which pro-
vides for but two circuit? or paths between the
brushes.
Single-Wound Wire. — Wire insulated by winding, or
otherwise, with a single layer of material only.
Sinistrorsal Solenoid. — A left-handed solenoid.
Sinusoid, — A curve of sines.
Sinusoidal Alternating Electromotive Force. — Alter-
nating electromotive forces represented as to vari-
ations in strength, by a sinusoidal curve.
Sinusoidal Currents. — Simple periodic currents the
strengths of which are represented accurately by
sinusoids.
242 ELECTRICAL DICTIONARY
Siphon Electric — A siphon which provides by electrical
means for the continuation of the flow of liquid,
which has ceased to flow, due to the accumulation
of air.
Siphon Recorder. — A recording apparatus in which the
inked marks are made on a strip of paper, the ink
being supplied by a siphon terminating in a cap-
illary orifice.
Siren. — An acoustic instrument serving to measure the
frequency of sound waves.
Six- Wire System. — A distributing system wherein five
dynamos are connected to six conductors, and
which partakes in general of the character of the
three-wire system.
Six-Wire Triphase System. — A system producing tri-
phase currents, in three distinct circuits, having
two wires each.
Skew Adjustment of Carbons in Arc-Lamps — A manner
of adjusting carbons in an arc lamp, the positive
carbon being placed a little in front of the negative
carbon, but out of vertical line with it.
Skidding of Car Wheels. — The sliding instead of the
rolling of the wheels of a car.
Skin Currents. — Rapidly alternating currents which
are confined to the superficial portions of a con-
ductor.
Skin Effect. — A tendency of currents of very brief
duration to flow through the outer layers and to
avoid the mass df a solid conductor.
Sled. — In a conduit system, a contact for an electric
car like the plow, except that it is drawn after the
car instead of being pushed ahead.
ELECTRICAL DICTIONARY 243
Sleeve Joint. — A joint obtained by inserting the ends of
the wires or electric conductors into a metallic tube
or sleeve of sufficient inside diameter to just admit
them, and then securing them by twisting and
soldering.
Slide Bridge. — A style of Wheatstone 's bridge, a single
thin wire representing one lateral pair of arms,
the other pair representing a resistance which is
known and the one to be ascertained ; and between
the known and the unknown resistance the gal-
vanometer is connected on one side, its connection
on the opposite side being moved back and forth
until the balance is obtained and the galvanometer
strikes zero.
Slide Resistance. — A rheostat the placing and remov-
ing of whose separate resistances of coils from a
circuit are effected by means of a sliding contact.
An instrument used in telegraphy and formed of
two slide rheostats divided into 100 parts each, but
constituting both together a rheostat in effect, sub-
divided into 10,000 parts.
Sliding Bed-Plate. — A bed-piece or plate of a belt-
driven dynamo which is capable of being moved
for the purpose of tightening the belt.
Sliding Contact. — A contact which is connected with
one part of a circuit and closes that circuit by being
slid over a conductor connected with another part
of the circuit.
Slings. — Polished copper wires used in electro-plating,
by which the article to be plated is suspended from
the negative rod in the depositing tank.
Slip of Induction Motor. — The ratio of difference be-
tween the speed of the rotary magnetic field by
244 ELECTRICAL DICTIONARY
which the motor is driven and the speed of the
rotor.
Slip of Rotor. — The ratio of difference between the
speed of a rotary magnetic field and that of the
rotor.
Slipping of Belt. — The speed lost by a revolving belt
due to its slipping on its pulley.
Slots on Armature Core. — The grooves in an armature
core designed to receive the armature coils.
Slot-Wound Armature. — An armature wherein the
windings 'are sunk in slots.
Slotted Armature. — An armature with grooves designed
to receive the wires. An iron-clad armature.
Slotted Conduit. — An underground conduit having a
slot which reaches to the surface of the roadbed,
by means of which a traveling conductor is enabled
to carry off the current from the conductors sup-
ported in the conduit.
Slow-Speed Electric Motor. — An electric motor having
the capacity to do efficient work at a slow speed.
Slow-Speed Generator. — A generator constructed for
the purpose of running at slow speed.
Smashing Point of Incandescent Electric Lamp. — A
time when an incandescent lamp has become so dis-
colored that it can no longer render efficient service,
and it is considered more economical to break or
remove it and put another in its place than to con-
tinue its use.
Smee Voltaic Cell. — A zinc-silver couple used with an
electrolyte of dilute sulphuric acid.
Smooth-Core Armature. — A cylindrical armature upon
whose even surface the coils are wound as dis-
tinguished from a slotted or iron-clad armature.
ELECTRICAL DICTIONARY 245
Snap Switch. — A switch so contrived as to give a quick
break, a spiral spring being fastened between the
handle and the arm in such a manner that when the
handle is drawn back to open it — the friction con-
tact holding the bar — (the spring suddenly pulls
the handle up and the contact is broken.
Snap Welding of Rails. — A welding joint for rails ef-
fective by clamping the rails together at their
short projections, and then rapidly heating the
ends and pressing them together when the re-
quired degree of heat for welding has been ob-
tained.
Sneak Current, — A comparatively weak current, enter-
ing by accident the circuit of a telephone or tel-
egraph line, and from which no instantaneous bad
effect would result; yet, if permitted to continue
circulating in a bell or annunciator coil, would
generate sufficient heat in a short time to burn it
out. A current not strong enough to melt the
regular safety fuses, yet of sufficient strength to
cause damage if permitted to continue.
Sneak Current Coil. — A coil of German silver wire em-
ployed to cut a telephone apparatus out of circuit
by melting a drop of fusible metal, when a sneak
current or current of dangerous strength has
raised the coil to a sufficient degree of heat.
Socket for Electric Lamp. — A receptacle for an incan-
descent lamp.
Socket Lamp. — A lamp having a socket.
Socket Switch. — A socket key.
Soft-Drawn Copper Wire. — Copper wire which has been
first drawn and then softened by annealing.
246 ELECTRICAL DICTIONARY
Soft Porous Cell. — A porous cell baked soft and when
employed in a voltaic cell obtains comparatively
low internal resistance.
Soldering, Electric. — A process in which heat generated
electrically is employed to melt the solder which is
used in making the metallic joints.
Soldering Flux. — Any solution serviceable for cleaning
the surfaces of articles preparatory to soldering.
Solenoid. — A helical coil of wire, of uniform diameter,
representing a cylinder and having one end of the
wire bent back and brought through the center of
the coil, both ends emerging at the same end. A
helical coil of wire of uniform diameter and cylin-
drical in form.
Solenoid Core. — A core consisting ordinarily of soft
iron introduced into a solenoid ; and in which posi-
tion the magnetic flux of the magnetizing current
magnetizes it.
Solid Arc-Light Carbon. — Carbon- electrodes employed
in arc lamps which have no core of softer carbon.
A carbon which is solid throughout, thus differing
from a cored carbon.
Solid-Back Telephone Transmitter. — A form of micro-
phone transmitter to a great extent used in long
distance telephone service.
Solid Thermostat. — A thermostat which depends for its
operation upon the expansion of a solid body or
upon the unequal expansion of two separate solid
bodies.
Solid Wires. — A single wire conductor, thus differing
from one composed of a number of parallel wires.
Soluble Electrodes. — Copper, iron or other metallic elec-
ELECTRICAL DICTIONARY 247
trodes which are used in metallic electrolysis and
which during electrolysis are converted into metal-
lic salts.
Solution. — The action of an attraction between one or
more solids and a fluid when brought in contact,
by which the former become themselves fluid, and
are diffused through the latter without other
change or loss of properties.
Sound. — An effect produced upon the brain through the
sense of hearing and caused by the vibrating
motion of sonorous bodies.
Sound Wave. — Waves produced in an elastic medium
by the vibratory motion of sonorous bodies.
Sounder Resonator. — A sounder whose intensity of
sound is increased by resonance; the sounder being
placed in a resonant case for that purpose.
Sounding Board. — An elastic board possessing resonant
properties and employed in stringed musical in-
struments.
South Magnetic Pole. — The pole of a magnetic needle
which tends to point to the geographical south of
the earth.
" Spare" Machine. — An additional machine of any kind
held in reserve in a plant to supply the place of
any like machine which may accidentally become
disabled.
Spark Arrester. — A screen made of wire netting, ad-
justed around the carbon of an arc lamp above the
globe, to obviate the scattering of sparks.
Spark Coil. — A wire coil, insulated and connected with
the main circuit, and used in a system of electric
gas lighting for lighting gas jets, which is effected
248 ELECTRICAL DICTIONARY
by means of the spark produced by breaking the
circuit.
Spark, Electric. — The phenomena observed when a dis-
ruptive discharge passes through a gap.
Spark Gap. — A space left between the ends of an elec-
tric resonator across which the spark jumps when
a certain difference of potential exists between two
opposing conductors.
Sparking Distance. — The distance traversed by the dis-
ruptive discharge in its passage through the air
space.
Sparking of Dynamo-Electric Machine. — An injurious
production of sparks at the commutator between
the brushes and commutator sections of a dynamo
electric machine.
Sparkless Commutation. — Commutation of a dynamo
which is not attended with sparking at the brushes.
Speaking Wire. — A wire connecting two telephone ex-
changes for the intercommunication of operators
as distinguished from subscribers' wires.
Specific Conductance. — Specific conductivity.
Specific Conctuctivity. — The reciprocal of specific resis-
tance. The specific resistance of a certain length
and area of cross-section of a body as measured
by the same length and area of cross-section of a
standard substance.
Specific Gravity. — The ration of the weight of a body
to the weight of an equal volume of some other
body taken as the unit or standard; water usually
being taken for solids and liquids, and air for
gases.
ELECTRICAL DICTIONARY 249
Specific Heat. — The capacity possessed by any mass
or body of matter for heat. The capacity of a body
for heat as compared with an identical quantity
of some other body taken as unity.
Specific Heat of Electricity. — A proposed term to ac-
count for the heat absorbed or given out by un-
homogeneous conductors, i. e., heat in purely ther-
mal phenomena and heat in thermo-electric phe-
nomena.
Specific Hysteretic Dissipation. — A loss of energy per
unit of volume occasioned by hysteresis in any sub-
stance. A loss of energy by hysteresis in a body
under specific conditions measured by a like loss
in a standard body.
Specific Magnetic Conductivity. — The specific permea-
bility of a body to magnetic flux.
Specific Magnetic Reluctance. — Specific magnetic re-
sistance.
Specific Magnetic Resistance. — Reluctivity.
Specific Magnetism. — A proposed term to express the
quotient of the magnetic moment by its mass.
Specific Resistance. — The relative resistance of a sub-
stance to the passage of electricity, as referred to
some standard substance. The actual resistance
of a cube of a substance which is one centimeter on
edge, being usually expressed in microhms for
metals and ohms for liquids. Specific conduction
resistance.
Specific Resistance of Liquids. — The resistance offered
by a specific length and area of cross section of
a liquid as measured by the resistance of the same
length and area of cross section in a standard con-
ductor.
250 ELECTRICAL DICTIONARY
Spectrograph. — A proposed term for radiograph.
Spectrophone. — An instrument used to examine the
ultra red portion of the spectrum.
Spectroscope. — An optical instrument for examining
spectra, particularly those produced by flames in
which different substances are volatilized, so as to
determine, from the position of the spectral lines,
the composition of the substance.
Spectrum. — The several colored and other rays of which
light is composed, separated by the refraction of a
prism or other means, and exhibited either as
spread out on a screen or by direct vision.
Speed Counter. — An instrument which records the num-
ber of revolutions which a shaft makes.
Speed and Direction Indicator. — A telegraph employed
on shipboard to indicate the propeller shaft revo-
lution as to speed and its movements as to direc-
tion.
Speed Indicator. — A speed counter.
Speed of Rotation. — The number of revolutions made in
any length of time. The distance which the cir-
cumference of a rotating wheel will pass over in a
given time.
Speed Recorder. — An instrument which records instan-
taneously the speed of a machine.
Speeding of Dynamo. — Modifying the speed of a dy-
namo in order to get the correct speed required
for the operation of an electro-receptive device
which has been put into the circuit.
Spelter. — Commercial zinc.
Spent Acid. — Acid which has lost its power of action
from long use.
ELECTRICAL DICTIONARY 251
Spent Liquor. — Liquor such as used in an acid or bath
which has lost its power of action from long use.
Spherical Aberration. — Incorrect outlines of the images
produced in a lens or mirror with special faces, due
to a defect in the curvature of one or both of the
faces and calling for as a remedy a slight depar-
ture from the true spherical form in order to pro-
duce a perfect image.
Spherical Armature. — A dynamo armature whose coils
are wound on a spherical core.
Spherical Candle-Power. — The average candle-power
of a luminous source in every direction. The aver-
age of a number of observations taken at different
angles, the source being moved about from one
position to another.
Spherical Candle-Power Measure. — An instrument
which measures, or by means of which is measured,
and by a single observation, the average spherical
candle power from a source of light.
Spherical Candle-Power Photometer. — A photometer
contrived for the measurement of the average
spherical candle-power of a lamp or of any lumi-
nous source from one observation only.
Spherometer. — An instrument for measuring the cur-
vature of a sphere.
Sphygmograph. — An instrument employed to record
the action of the pulse and usually applied to the
radial artery at the wrist.
Sphygmophone. — An apparatus embracing a michro-
phone and employed to examine the pulse.
Spider. — A radial bracket serving to support an arma-
ture or machine on a revolving shaft.
Spider Arm. — A projection of a spider.
252 ELECTRICAL DICTIONARY
Spiral. — A term used at times, signifying an open con-
ducting coil, as, for instance, the primary or sec-
ondary of an induction coil or transformer.
Spiral Loop System of Distribution. — A term used to
signify a variety of parallel distribution, employed
to obtain a uniform distribution of potential, the
parallel conductors being extended in the arcs of
spirals throughout the district to be served, from
the power station; both spirals reaching from one
nearly to the other generator.
Spiral Windings. — Solenoidal winding.
Splice Bar. — A fish plate used in railroad construction
for joining the ends of rails.
Splice Box. — A box which contains the splices in elec-
tric lines and underground cables, the splicing or-
dinarily being effected in the boxes.
Splicing. — Uniting the armor or protecting coverings
of the two ends of a cable at a joint.
Splicing Ear. — A trolley ear serving to join the ends
of trolley wire.
Split Battery. — A battery of a number of voltaic cells,
connected in series, with their central portion
grounded or connected to the earth.
Split Condenser. — A condenser designed by its arrange-
ment for the convenient inter-connection of its dif-
ferent sections in the same circuit, or for their em-
ployment in different circuits as occasion may de-
mand.
Split Current. — A current that is divided. A current
taken from the main telegraph wire.
Split Phase. — The difference resulting in the phases of
alternating currents produced by the division of a
uniphase alternating current.
ELECTRICAL DICTIONARY 253
Split-Phase Motor. — A multiphase motor which by the
introduction of a phase-splitting contrivance is
operated from a Uniphase alternating-current cir-
cuit. A multiphase motor wherein from a single-
phase circuit the multiphase currents are locally
produced.
Split-Secondary of Induction Coil. — A secondary of an
induction coil that is divided into two equal parts.
Spluttering of Arc. — A spluttering noise emanating
from a voltaic arc while it is forming.
Spot. — A bright spot of light which appears on the
scale of the mirror galvanometer.
Spotty Filament. — An incandescent lamp filament
which presents points of unequal brilliancy when
raised to incandescence by the passage of the cur-
rent and which is due to local variations of resist-
ance.
Spreading the Magnetic Field. — Deviation of a mag-
netic field:
Sprengal Mercury Pump. — An air pump, a column of
mercury in which acts as a piston, the actuating
force being the weight of the column, which is re-
quired to exceed thirty inches in height.
Spring Ammeter. — An ammeter in which the part
moved by the current is controlled or brought to
the zero position by a spring.
Spring Clips of Switch. — Spring clips of a switch which
hold the blades when closed.
Spring Contact. — A spring connected to one lead of an
electric circuit, arranged to press against another
spring or contact point which it opens or closes.
254 ELECTRICAL DICTIONARY
Spring Dynamometer. — A dynamometer which depends
for its operation upon the action of a spring.
Spring Jack. — A spring contact having a hole in it pro-
vided for the introduction of a plug.
Spring Relay-Contact. — A style of relay contact which
is stopped by a spring when the circuit is broken.
Spring Voltmeter. — A voltmeter the potential differ-
ence in which is determined by a magnetic needle
moving against the pull of a spring.
Spurious Hall Effect. — A spurious electro-motive force
caused in an electric conductor, through which a
current is flowing, by variations in conductivity of
the conductor produced by a magnetic field.
Spurious Resistance. — The counter-electro-motive force
operating to prevent a current from being pro-
duced to that extent which would be its full
strength were the true resistance and actuating
electromotive force only involved.
Square Mil. — A unit of area equal to .000001 square
inch and used in the measurement of the areas of
cross section in wires.
Squirted Filament. — An incandescent lamp filament ob-
tained by forcing with pressure a carbonized car-
bonaceous composition through a hole of proper
shape.
Stable Equilibrium. — That equilibrium of a body rest-
ing upon a base, which requires its center of grav-
ity to be raised in order to upset it.
Stage Regulator. — A controller employed in a theater,
and located near the stage, by means of which the
incandescent lamps can be lighted, extinguished, or
their brilliancy varied.
ELECTRICAL DICTIONARY 255
Staggering of Dynamo Brushes. — A term used indicat-
ing a certain position of the brushes on a commu-
tator cylinder, one brush being set just forward of
the other in order that the formation of the grooves
caused by wear may be obviated.
Standard Candle. — A standard of illuminating power,
generally understood to be the English standard
sperm candle, which when burning at the rate of
two grains of sperm wax per minute produces a
light of a brightness equal to one candle power.
Standard Compass. — A compass employed on shipboard
as a standard with which to compare and check
other compasses.
Standard Earth-Quadrant. — A length approximating
10,000 kilometers, one-quarter of the earth's meri-
dian circle, through Paris. A unit of inductance ;
the henry.
Standard Luminous Intensity. — A unit of luminous in-
tensity taken as a standard.
Standard Megohm. — A resistance which is equal to one
million ohms.
Standard Ohm. — A piece of pure copper wire, one cir-
cular mil in diameter, and one foot long at a certain
temperature.
Standard Resistance. — A known resistance employed to
determine unknown resistances by comparison.
Standard Resistance Coil. — A coil having a resistance
of a standard ohm or a multiple of a standard ohm.
Standard Voltaic Cell. — A voltaic cell employed as a
standard in the measurement of unknown electro-
motive forces, by reason of its own electromotive
force being practically constant.
256 ELECTRICAL DICTIONARY
Standard Wire Gauge. — A wire gauge adopted by the
National Electric Light Association and the Na-
tional Telephone Exchange Association of Amer-
ica ; its gauge numbers ranging from 0000 — .46 inch
diameter to 40 — (.00314 inch diameter.
Standards. — Supports located on the roofs of buildings
and employed to support telephone wires. Any
standard, such as a resistance coil or voltaic cell
used for making comparisons. The support for
the bearings of a dynamo and some other machines.
Standardized Resistance Coil. — A coil whose resistance
has been determined by careful comparison with
a standard.
Standardizing a Voltaic Cell. — Ascertaining the precise
value of a voltaic cell's electromotive force, so
that it will serve as a standard of comparison.
Star Current in Polyphase System. — In a polyphase sys-
tem, the current between any terminal and the
neutral point, or the current in any branch of the
system.
Star Potential in Polyphase System. — In a polyphase
system the difference of voltmeter pressure or of
potential between any terminal and the neutral
point.
Star Triphase-Winding. — The connecting together of
three triphase windings at a common junction, the
three free ends being connected to the terminals.
Starting Box. — A starting resistance.
Starting Box for Electric Motor. — A resistance by
which an electric motor is started.
Starting Box of Shunt-Wound-Motor. — A box which
has a rheostat whose resistance is variable and em-
ELECTRICAL DICTIONARY 257
ployed in connection with the armature circuit of a
shunt-wound motor in order to impede the rush of
current which attends the connection of the motor
with the driving circuit.
Starting Current of Motor. — The current which tra-
verses the coils of a motor when it first starts.
Starting Motor for Synchronous Motor. — A small elec-
tric motor serving, at times, to obtain the proper
speed for the armature of a synchronous single
phase motor before making the connection with the
driving-current circuit.
Starting Position of Street-Car Controller. — The posi-
tion of a controller switch on a street-car at which
the current is first taken into the motors at start-
ing.
Starting Rheostat. — Coils of wire mounted and con-
nected so that they can be introduced in the circuit
of a motor in succession while it is being started.
Starting Torque of Motor. — -The torque necessary to
start a motor and that which is developed by the
motor when starting.
Static Breeze. — The silent or brush discharge of high
tension electricity.
Static Discharge. — Disruptive discharge.
Static Electricity. — Electricity generated by friction.
Static Energy. — That energy which a body possesses
when at rest due to advantage of position or other
causes, such as the stress of a spring or the foot
pounds of a pound weight supported a certain num-
ber of feet above a plane.
Static Hysteresis. — ,A phenomenon of magnetization of
iron attributed to molecular friction, by reason of
258 ELECTRICAL DICTIONARY
which considerable energy is expended during
every reversal in its magnetization as contradistin-
guished from viscous hysteresis.
Static Shock. — A term in electro-therapeutics for a
method of applying static discharges from small
condensers or Leyden jars to a patient who is in-
sulated from the ground with one electrode ap-
plied to the conducting surface on which he rests,
while the other, spherical electrode, is brought near
the body so as to produce a disruptive or spark
discharge.
Static System of Induction Telegraphy. — A mode of
electric communication without any metallic con-
nection between the stations; but which depends
upon static induction between the instruments for
sending and receiving. Wireless telegraphy.
Static Transformer. — A term used to distinguish the
ordinary transformer from a rotary transformer.
Statics. — That branch of mechanics which treats of the
equilibrium of forces, or relates to bodies as held
at rest by the forces acting on them ; in distinction
from dynamics, or the science of forces producing
motion.
Static Circuit-Breaker.— 4A circuit breaker employed in
a central station.
Station Load. — The entire load on a central station at
any time.
Station Load-Curve. — A curve which represents the
station load at any time.
Station Recording- Wattmeter. — A wattmeter adaptable
for central stations for the purpose of recording
the energy delivered.
ELECTRICAL DICTIONARY 259
Station Transformer. — A transformer used in a central
station, or one which supplies a load in a station.
A transformer designed to furnish the current for
potential indicators and lamps on the station
switchboard.
Stationary Transformers. — A term used to signify alter-
nating-current transformers as contradistinguished
from rotary transformers.
Stationary Electric Motor. — An electric motor firmly
attached to the ground or floor as contradistin-
guished from one which moves about.
Stationary Tachometer. — A tachometer which indicates
the number of revolutions per minute of a shaft in
a stationary rotating machine.
Stator. — The stationary portion of a rotary field induc-
tion motor in distinction from the portion which
rotates.
Stator Armature. — A dynamo or motor armature which
remains at rest while the machine is in operation.
A part of a machine which is at once its armature
and immovable.
Statute Mile. — -A British statute mile equal to 5,280 feet.
Steady Current. — A current whose strength is fixed or
invariable.
Steam Governor, Electric. — An electric device whose
employment in connection with a valve regulates
the supply of steam to an engine so that the engine
is driven at a speed such as to maintain a constant
potential or a constant current.
Steam-Turbine Dynamo. — A dynamo of high speed, a
steam turbine being employed to drive the arma-
ture.
260 ELECTRICAL DICTIONARY
Steering Compass. — A compass provided on shipboard
for steering a ship.
Steering, Electric. — Steering by means of electricity.
Step-Down Converter. — A step-down transformer.
Step-Down Transformer. — A transformer which trans-
forms a small current of great difference of poten-
tial into a large current of small difference of po-
tential.
Step-Up Converter. — A step-up transformer.
Step-Up Transformer. — A transformer which trans-
forms a large current of small difference of poten-
tial into a small current of great difference of po-
tential.
Stereopticon. — An instrument provided with a lantern
and other accessories and used to project the
images of objects upon a screen so that they stand
out in relief.
Sterilization, Electric. — A mode of sterilizing solutions,
which consists in destroying the germs by means of
electric currents.
Stethoscope. — An instrument for ascertaining the condi-
tion of the heart, lungs, and system of circulation
generally by the sound they produce.
Sticking of Magnetic Armature. — The adherence after
the current is cut off of the armature to the poles
of the magnet.
Stiff Field. — A magnetic field whose density is compar-
atively great.
Stock Ticker. — An instrument employed in brokers' of-
fices and elsewhere for receiving quotations and
other information by means of printing appearing
ELECTRICAL DICTIONARY 261
upon a ribbon of paper which is fed from the in-
strument.
Stock-Ticker Service. — The service which supplies stock
quotations from the stock exchange to subscrib-
ers.
Stopper Incandescent Lamp. — An incandescent lamp
having the filament mounted in the chamber of a
closely fitting stopper instead of by being sealed
hermetically in the lamp chamber.
Storage Accumulator. — A storage battery.
Storage Battery. — A group consisting of a number of
distinct storage cells so connected together as to
form a single electric service.
Storage Battery Car. — A motor propelled car whose mo-
tor receives its current from storage batteries. A
car used to convey storage batteries.
Storage Battery Meter. — A meter employed in connec-
tion with a storage battery and serving to indicate
the quantity of electric energy remaining in the
battery.
Storage Battery Traction. — Car traction electrically
created by means of storage batteries.
Storage Capacity. — A name signifying the ampere
hours of electricity which can be obtained from a
storage battery in current form.
Storage Cell. — Two plates of metal or compounds of
metal whose chemical relations are changed by the
passage from one plate to the other of an electric
current through an electrolyte into which they have
been immersed. A term applied to a jar which con-
tains but one cell.
Storage of Energy. — The transformation from kinetic
to potential energy.
262 ELECTRICAL DICTIONARY
Stranded Conductor. — A conductor which consists of a
number of fine twisted conductors and designed
either to obtain greater flexibility or to reduce self-
induction or Foucault currents.
Strap Key. — A key for which a strap of metal is used
in the manufacture.
Strap Switch. — A switch for which a strap of metal is
used in the manufacture.
Stratification Tube.— A tube which, through a high
vacuum, shows the stratification of the electric
discharge. A Geissler tube.
Stray Currents. — Eddy currents. Foucault currents.
Stray Field. — In a dynamo or motor the section of the
field whose lines of force or magnetic flux leakage
are not passed through by the armature windings.
Stray Flux.— The flux of a stray field.
Street Car Controller. — An electrical device enclosed
in a box on the car-platform and serving to regu-
late the speed of an electric car.
Street-Car Lamp. — An incandescent lamp whose fila-
ment is anchored and adaptable for use in street
cars.
Street-Car Motor. — A motor used to propel trolley cars.
Street-Car Recording Wattmeter. — A wattmeter de-
signed for recording the supply of energy received
by a street-car in a specified length of time.
Street Load-Diagram. — A diagram made to show the
electric load on the different streets in a district
supplied with electricity.
Street Mains. — The conductors in a system of electric
distribution, which extend through the streets be-
tween the different junction boxes and which serve
ELECTRICAL DICTIONARY 263
to distribute the current from the feeders and with
which service wires are connected.
Street Railway, Electric. — A street railway which is
operated by electricity or power supplied elec-
trically.
Street Service. — That part of a circuit in a system of in-
candescent lamp distribution which extends from
the main to the cut-outs, and which is external to
the building or structure supplied.
Strength of Current. — Amperage — (Quality of current
in a circuit.
Strength of Magnetic Field. — The intensity of a mag-
netic field at any point determined by the force
with which it acts on a unit magnet pole located at
that point.
Stress. — Force acting upon a solid body by pull, pres-
sure or in other ways, and which produces distor-
tion or strain.
Stress Flux. — Flux from whose action a stress results.
Striking an Arc. — 'Moving the carbon electrodes apart
in order to form an arc between them.
Striking Bath. — A bath used in silver plating and which
contains a larger proportion of free cyanide than
of silver, thus obtaining instantly a deposit upon
the object to be plated, before it is placed in the
regular plating bath.
Striking Distance. — Sparking distance. The distance
which a disruptive charge will traverse.
Striking Mechanism of Arc Lamp. — Mechanism which
separates the carbons in an arc lamp when the arc
is formed.
Strip Fuse. — A safety strip.
264 ELECTRICAL DICTIONARY
Strip Resistance. — lA resistance in which strip conduc-
tors are employed.
Stripping Liquid. — The liquid in a stripping bath. The
liquid used in the process of removing the super-
ficial layer of one metal from the surface of another
by electrolysis.
Strong-Current Arrester. — An arrester adaptable for
the protection of a line against currents resulting
from contact with a trolley circuit or any other
circuit of strong current.
Struck. — A term in electro-plating used in relation to
metallic surfaces which have been electrolytically
covered with a film of silver or nickel by immersion
in a bath and exposure for a few seconds to the
action of a strong current.
Structural Carbon. — A lamp filament produced by car-
bonizing any structural material capable of being
carbonized, as bamboo for instance.
Structureless Carbons. — Lamp filaments produced by
carbonizing structureless materials, as for instance
tamine and other materials.
Sub-Aqueous Cable. — A cable used in sub-aqueous
work usually in fresh water. Cables used in rivers
in distinction from sub-marine or ocean cables.
Sub-Center Transformer. — A transformer located at a
sub-center of distribution and which supplies sec-
ondary circuits radiating therefrom.
Sub-Divided Conductor. — A multiple-wire, stranded or
composite conductor.
Sub-Divided Transformer. — A transformer in whose
primary or secondary coils there are subdivisions.
A transformer whose magnetic circuit is subdi-
vided.
ELECTRICAL DICTIONARY 265
Sub-Exchange for Telephones. — »A subordinate ex-
change. A local exchange operating under a cen-
tral exchange.
Sub-Mains. — Branch conductors from mains.
Sub-Marine. — Under the sea.
Sub-Marine Boat, Electric. — A boat so constructed as to
be driven and steered under water.
Sub-Marine Cable. — A cable intended for use* under the
ocean.
Sub-Marine Finder. — A proposed form of induction bal-
ance for locating submerged bodies or objects of
metal, such as ships, anchors, torpedoes, etc.
Sub-Marine Fuse. — A fuse serving to ignite and explode
a sub-marine mine.
Sub-Marine Key. — A key employed in sub-marine tele-
graphic operations.
Sub-Marine Mine. — A mass of highly explosive material
confined in water-tight metallic receptacles and
sunk in the water for the purpose of destroying by
an explosion the vessel of an enemy which may
pass over them.
Sub-Marine Search Light. — An incandescent light serv-
ing to explore under water.
Sub-Marine Sentry. — A water kite, situated under a ves-
sel, and employed in sub-marine cable work to in-
dicate very shallow places in the water, by rising
to the surface when touching sea-bottom.
Sub-Marine Telegraphy. — Trans-oceanic telegraphy. A
system of telegraphy employing a sub-marine cable
as a line wire.
Sub-Marine Telephony. — Telephony effected by the use
of sub-marine cables.
266 ELECTRICAL DICTIONARY
Sub-Permanent Magnetism. — A term applied to magnet-
ism present in an iron ship and meaning that such
magnetism is not as marked as that present in a
bar of magnetized steel.
Sub-Station. — An auxiliary station.
Sub-Station Accumulator. — An accumulator used at
sub-stations.
Sub-Station Transformer. — A transformer used at sub-
stations.
Subway, Electric. — An underground passage way util-
ized to receive electric-light wires or cables.
Sulphating. — In storage battery cells, the formation of
a hard, white basic sulphate due to over-exhaustion
of the cells resulting in a loss in the operation of
the cells.
Sunflower Commutator. — A commutator whose appear-
ance resembles that of a sunflower. A style of disc
commutator.
Sun-Light Color- Values. — 'Luminous frequencies which
give to the light of an artificial source the same ef-
fects which sunlight produces.
Sun-Spot Disturbance. — Disturbance due to the pres-
ence of spots on the sun.
Sun-Spots. — Dark areas which are observed at times on
the sun's surface.
Sun-Stroke, Electric. — Effects due to exposure to the
arc light and similar to those produced by sun-
stroke.
Sun Telegraph. — /The heliograph.
Sunk Winding. — An iron-clad winding. A winding
made in slots or grooves and buried below the sur-
face of an armature.
ELECTRICAL DICTIONARY 267
Superposed Magnetism. — A term which characterizes
a magnetism impressed on a substance which has
already been magnetized.
Super-Saturation. — The condition assumed by a solu-
tion which has cooled below its solidifying point
while not exposed to air.
Super-Saturation of Solution. — The condition obtained
when a warmed saturated solution of salt, con-
tained in a tight vessel, has cooled without ex-
posure to the air, being shaken.
Supplement of Angle. — That which is required to bring
the value of an angle to 180 degrees.
Supplementary Dynamo. — A term signifying a booster
dynamo.
Supply Meter, Electric. — A meter whose function is to
measure the supply of electricity furnished to a
machine or a purchaser.
Support Plate of Storage Cell. — A storage cell's grid.
Surface Action. — Action confined to a surface.
Surface Contact of Street-Railway Car. — A contact
which is situated on a level with the street surface
and designed for use in an electric street railway
system in connection with the driving of the cars.
Surface Contact Street Railway System. — A third rail
system. An electric street railway system in which
surface contacts are used.
Surface Integral of Magnetic Induction. — The entire
volume of magnetic flux which passes through a
surface.
Surface-Wound Armature. — An armature wound upon
its surface, the conductors lying on the surface of
ELECTRICAL DICTIONARY
its coil, instead of being wound in grooves like the
iron-clad armature.
Surgical Lamp. — A lamp used by surgeons for examin-
ing and operating upon the human body.
Surgical Circuit. — A circuit having a surging discharge
passing through it.
Surging Discharge. — The disruptive or sudden dis-
charge of such a static condenser as a Ley den jar,
or of any other charged conductors; the discharge
being oscillatory in character.
Surgings, Electric. — Oscillating vibrations present in a
conductor which is rapidly discharging or being
charged. Direct or induced electric oscillations.
Susceptance. — A quantity, in an alternating-current
circuit conductor, whose square plus the square of
conductance equals the square of admittance.
Suspended-Coil Galvanometer. — A galvanometer with a
suspended coil by the movements of which a cur-
rent passing through it is measured.
Suspension. — The mechanism by which anything is sus-
pended. The means by which any apparatus or ac-
cessory thereto is suspended, as for instance a car-
motor, pendulum, needle, etc.
Suspension for Car-Motor. — The means by which a car-
motor is kept in position on the truck of a car.
Swage. — A tool variously shaped or grooved on the
end or face and used by workers in metals for shap-
ing their work, whether in sheet metal or forging,
by holding the tool upon the work or the work
upon the tool and striking with a sledge.
Swage. — To shape heated metals by means of a swage ;
to fashion, as a piece of iron, by drawing or ham-
ELECTRICAL DICTIONARY 269
mering it into a groove or mould having the re-
quired shape.
Swaging. — The shaping of heated metals by drawing or
hammering them into a tool having the required
shape.
Swaging, Electric. — Swaging metals while softened by
electric heat (see swaging).
Sweating. — A process by which the ends of electric-
light cables are soldered together.
Swinging Cross. — A term applied to an intermittent
cross.
Swinging Earth. — A term applied to an intermittent
earth.
Swinging Voltmeter. — A voltmeter which can be read
from any direction, being supported on a swinging
bracket attached to a switchboard.
Switch. — A device for opening and closing an electric
circuit.
Switch-Bell. — A switch and bell combined.
Switch Blade. — The blade of a switch. A conducting
strip.
Switch-Board. — A board or tablet to which wires are
led connecting with cross bars or other switching
devices, so as to allow connections to be made with
other circuits or between themselves. A board
equipped with switches and instruments which
serve to control a distribution system and the gen-
erators employed in it. A board equipped with
switches for opening or closing or interchanging
electric circuits connected with it.
Switch-Board Fittings. — A general term applied to the
divers fittings or accessary devices of a switch-
270 ELECTRICAL DICTIONARY
board, such as connectors, set-screws, wire-holders
or bus-bar connections, by means of which the dif-
ferent apparatuses are placed upon the board,
Switch-Board Transformers. — Transformers serving on
an alternating-current switch board to furnish lo-
cally alternating currents of reduced pressure.
Switch-Board Wattmeter. — A wattmeter mounted on a
switch board and whose functions is to indicate the
quantity of energy which some circuit connected
therewith puts out or takes in.
Switched-In. — Placed in a circuit by the manipulation
of a switch.
Switched-Out. — Kemoval from a circuit by the manipu-
lation of a switch.
Swivel Clevis. — A nut and bolt contrivance used to take
up slack in guy-rods.
Symmetrical Alternating Current.— An alternating cur-
rent, the suggestive alternations of which have op-
posite values but equal to each other, differing only
with respect to direction.
Symmetrical Magnetic Field. — A field of symmetrically
distributed magnetic flux.
Symmetrical Polyphase System. — A polyphase system
which with respect to pressures, conductors, cur-
rents and loads is symmetrically arranged.
Sympathetic Electric Vibrations. — Electric vibrations
which the electro-magnetic waves sent out by one
circuit produces in another. Electric vibrations
due to resonance.
Synchronism. — Occurrence of two or more events simul-
taneously. Unison of recurrence in apparatus of
ELECTRICAL. DICTIONARY 271
alternating-current systems occurring at the same
time.
Synchronize. — To agree in time ; to be simultaneous. To
effect concurrence or unison and coincidence of
phase in two alternating-current machines in order
to connect them together electrically.
Synchronizer. — That which causes synchronism. A con-
trivance which indicates when synchronism has
been reached in alternators to be connected in par-
allel.
Synchronizing Dynamo-Electric Machine. — The act of
adjusting the recurrences and phases of two alter-
nating-current dynamos in order that they may be
connected in parallel.
Synchronizing Torque. — The torque which tends to
bring into synchronism its own alternating-current
generator armature with some other armature oper-
ating with it.
Synchronous. — 'Simultaneously occurring, usually un-
derstood as co-periodic and co-phasal in distinction
from periodic agreement only.
Synchronous Generator, — An alternating-current gen-
erator capable of synchronous operation with an-
other generator.
Synchronous Motor. — An alternating-current motor
which will operate properly only after being
brought into step with the driving current.
Synchronous Multiplex Telegraphy. — A system of teleg-
raphy in which a number of messages are transmit-
ted simultaneously over a single wire, all in one
direction, or some in one direction and some in the
opposite.
272 ELECTRICAL DICTIONARY
Synchronous Vibrations. — Vibrations excited by several
distinct systems which are in exact unison both in
recurrence and phase.
Synthesis. — The uniting of elements to form a com-
pound. The opposite of analysis.
T.
T-Connector. — A connector similar in shape to the let-
ter T and serving to conect a wire with two branch
wires.
Table Push. — A push button connected with a call-bell
and located on a table for convenience in ringing.
Tablet Board. — A panel switchboard or one divided into
tablets.
Tachograph. — An instrument which records the number
of revolutions made in a machine or shaft per min-
ute.
Tachometer. — An instrument for measuring the velocity
and variations of velocity of machines and shafts
and indicating on a dial the number of these revo-
lutions per minute.
Tail of Mercury. — A trail left behind a drop of impure
mercury when drawn over a surface, indicating the
presence of oxides.
Tailings. — In a telegraph line, the prolongation of a
current at the remote receiving station due to self-
induction and the discharge of the line. The inter-
ference with the definiteness of signal marks due to
retardation in high speed transmission of telegraph
signals by the automatic system. Residual dis-
ELECTRICAL DICTIONARY 273
charges through the receiving instrument from the
line producing wrong marks.
Talking Circuit. — A circuit in a telephone system which
a subscriber uses during conversation in distinc-
tion from a circuit used for calling.
Tamadine. — A form of cellulose, used for making the
filaments of an incandescent lamp by cutting the
material into proper shapes and then carbonizing
them.
Tangent. — A right line touching an arc at one extrem-
ity and terminated by a secant passing through
the other extremity.
Tangent and Sine Galvanometer. — A galvanometer pro-
vided with two magnetic needles differing in
length, the shorter serving to measure tangents
and the longer being used for sine measurements
of current strength.
Tangent Scale. — An arc of a circle wherein the number
of graduations in any arc commencing at zero are
proportional to the tangent of the angle which such
arc subtends; thus, the scale, instead of being di-
vided into degrees, is divided into arcs of varying
lengths, which obviates the necessity of consulting
tables to find tangents corresponding to the de-
grees.
Tanning, Electric. — The tanning of leather by means of
electric currents.
Tap. — A conductor connected to a larger conductor as
a shunt. A derived circuit serving to carry off a
portion of a main current.
Tap Wires. — The conductors serving in trolley systems
to take the current from the mains at a pole to an
adjacent point on the trolley wire.
274 ELECTRICAL DICTIONARY
Taped Wire. — A wire insulated with a material similar
in form to tape, or insulated with a suitable ma-
terial and then wound with tape.
Taping. — Wrapping insulated tape around a wire or
joint.
Taps. — Branches which connect with mains and are
taken from them into the different apartments and
to the fixtures in a building supplied by a system
of incandescent lamp distribution.
Target, Electric. — A target which registers automatical-
ly by means of electricity the points struck by a
ball.
Teaser, Electric. — A fine wire coil wound on the field
magnets of a dynamo in shunt with the regular
magnet.
Teaser Winding. — An extra coil with which the arma-
ture of a monocyclic generator is wound and con-
sisting of less turns and smaller cross-section than
the main winding, one end ol it being connected to
a collecting ring, while the other is connected with
the center of the main winding.
Teeth of Armature. — Ridges projecting from the sur-
face of an armature core in which the armature
conductors rest.
Tel-Autograph. — A system of telegraphy by means of
which the reproduction of writing in fac-simile is
effected at a distance.
Tele-Barograph. — An instrument which records the in-
dications of a barometer at a distance.
Tele-Barometer, Electric. — A barometer which records
by means of electricity the indications of baromet-
ric pressure at a distance.
ELECTRICAL DICTIONARY 275
Telegraph. — An instrument or apparatus, or a process
for communicating intelligence rapidly between
distant points by employing signs representing
words or ideas and transmitted by means of elec-
tricity over conductors.
Telegrapher's Cramp. — A disease of the hand sometimes
contracted by telegraph operators and caused by
the too excessive use of the muscles of the hand in
telegraphing.
Telegraphic Box-Sounder. — A sounder having its re-
ceiving magnets confined in a resonant box in order
that the intensity of the sound may be increased.
Telegraphic Interrupter. — A defect in a line which in-
terferes with the transmission of telegraphic com-
munications.
Telegraphic Key. — A key or switch used by an operator,
by means of which he makes-and-breaks the cir-
cuit in a manner to correspond to the dots and
dashes of the Morse alphabet.
Telegraphic Repeater. — An extension of the relay sys-
tem adopted for long lines. An instrument which
causes the telegraphic apparatus in a station to re-
peat the message into another circuit.
Telegraphic Stock-Printer. — An instrument which
prints on ribbons of paper the quotations of stock
transmitted from the stock exchange.
Telegraphic Time-Service. — Time distribution by tele-
graph. Time sent out to subscribers from a stand-
ard clock by means of electricity.
Tele-Hydro-Barometer. — An instrument employed to
record and indicate at a distance the height of
liquids in a vessel or receptacle.
276 ELECTRICAL DICTIONARY
Tele-Hydro-Barometer, Electric. — An instrument em-
ploying electricity to effect the record and regis-
tration of the height of liquids in a vessel or re-
ceiver at distant stations.
Telephone. — An instrument which transmits articulate
speech by means of electricity.
Telephone Battery. — Any style of open-circuit battery
which can be adapted to use in telephone service.
Telephone Cable. — A cable either overhead or under
ground which is adaptable for the transmission of
telephonic messages.
Telephone Call-Bell. — A bell serving to call the person
with whom the subscriber desires to speak.
Telephone Call- Wire. — A wire used in some systems by
means of which a subscriber is enabled to call up
the central office. A special wire for calling.
Telephone Cords. — Flexible cords used for the conven-
ient moving about of telephone receivers and for
other purposes.
Telephone Cross-Talk. — An interference in a circuit re-
sulting from induction or leakage from an ad-
jacent circuit.
Telephone Drop. — A contrivance corresponding to an
annunciator drop and employed on a switchboard.
Telephone Exchange. — A central station fully equipped
with circuits, switches and all the other accessories
of a complete apparatus, which are employed to
place subscribers in communication with each
other, or with another exchange.
Telephone-Exchange Switchboard. — A central station
switchboard by means of which subscribers are
readily placed in connection with each other.
ELECTRICAL DICTIONARY 277
Telephone Galvanometer. — A galvanometer of high re-
sistance, comprising an electro-magnet with a thin
plate or disc of iron carefully adjusted between its
poles and bridged permanently across the circuit
of a telephone in order that visual call-signals may
be given.
Telephone Head-Gear. — An appliance for the head en-
abling a telephone receiver to be attached conven-
iently to the ear of the operator.
Telephone Repeating-Coil. — A style of induction coil
serving to repeat telephonic messages. An induc-
tion coil provided with an insulated winding in
each of the two circuits to be connected.
Telephone Set. — A term in its usual application signify-
ing the apparatus which a telephone subscriber
uses at his business place or home.
Telephone Tinnitus. — A nervous disorder of the audi-
tory sense caused by continual use of the telephone.
Telephone Transformer. — An instrument which serves
to repeat a telephonic message from one circuit into
another.
Telephonic Receiver. — That part of a telephone appara-
tus which is used to receive the message by placing
it in contact with the ear.
Telescope. — An optical instrument employed in view-
ing distant objects and which enlarges the visual
angle under which they are seen, thus increasing
their apparent dimensions.
Temper. — To render metals hard and elastic by sudden-
ly cooling them while heated.
Temperature. — Condition with respect to heat or cold
as indicated by the sensations produced or by the
thermometer or pyrometer. Degree of heat or cold.
278 ELECTRICAL DICTIONARY
Temperature Alarm, Electric. — »An electric device de-
signed to give an alarm and which is automatically
operated by a change of temperature.
Temperature Elevation.— The temperature of a body in
excess of its surroundings. The temperature of a
conductor which, due to the passage of a current
through it, is greater than that of the surrounding
atmosphere.
Temperature Gradient.— A line which indicates the
rate-of-change in an object or mass through which
heat is passing.
Tempering. — Rendering metals hard and elastic to dif-
ferent degrees required by heating them to various
temperatures and then cooling them suddenly.
Temporary. — Lasting for a time only.
Temporary Currents. — Currents which continue for a
short time only.
Temporary Intensity of Magnetization. — The intensity
of magnetization induced for a short while in soft
iron in distinction from that permanently induced
in steel.
Temporary Magnetization. — A term applied to the mag-
netization induced in a body of soft iron when sub-
jected to the influence of a magnetic field.
Tenacity. — That quality of bodies which keeps them
from parting without considerable force.
Tension. — The degree of stretching to which a wire,
cord and the like is strained by drawing it in the
direction of its length. Strain. The force with
which particles of gas tend to recede from each
other and occupy a larger space.
Tension, Electric. — A term not properly used, signify-
ELECTRICAL DICTIONARY 279
ing electromotive intensity, electromotive force,
dielectric stress or difference of potential, all of
which should be designated by their proper terms.
Terminal Pressure. — The pressure indicated at electric
terminals.
Terminal Voltage. — Terminal electromotive force.
Terminals. — The poles or electrodes of a voltaic bat-
tery.
Tesla Coil. — An induction coil insulated by means of
oil.
Tesla Discharge. — A disruptive discharge of exceeding-
ly high frequency.
Tesla Frequencies. — Frequencies higher than those
usually employed.
Tesla Transformer. — An oil insulated transformer which
raises the potential and decreases the current in
the secondary and used by Tesla to obtain high
frequencies.
Test Board. — A board which is equipped with spring
jacks or switches connected with separate lines to
facilitate the ready connection of testing instru-
ments with any particular lines and employed prin-
cipally in telephone and telegraph central offices.
Test Ring. — A call from central station made to the sub-
scribers in order to learn whether or not the line is
in good working condition.
Test Thimble. — A thimble provided with a contact and
serving in telephone exchanges to make a busy test
at a multiple switchboard.
Test Wire for Multiple Switchboard. — A wire making a
connection with the jacks of the same number of
the different sections on a multiple switchboard at
280 ELECTRICAL DICTIONARY
a central station, and which enables the operator
to ascertain whether a subscriber called is busy
or not.
Testing. — Making a trial to determine electric ability.
Determining the factors of electric capacity gen-
erally in a circuit.
Testing Bank. — A bank employed in testing circuits,
consisting of lamps or other resistances and having
no induction.
Testing Car for Railway Circuits. — A trolley car serv-
ing to make electric test while in motion.
Testing, Magneto. — A magneto-electric machine which
produces the high electromotive force necessary to
test circuits of high resistance.
Testing of Joints. — -Ascertaining in any circuit the usual
insulation or conductor resistance of a joint.
Testing Room. — A room equipped with all the necessary
apparatus for electric testing. A room on ships
used for cable laying, which is equipped with neces-
sary apparatus for signaling and making tests.
Testing Transformer. — A transformer employed in test-
ing to discover the efficiency or otherwise of all
those factors which enter into the operation of an
electric distribution system.
Tetanus. — Persistent spasm of the voluntary muscles.
Lockjaw.
Tetrad Atom. — An atom whose atomicity is four.
Tetrivalent. — Having an atomicity of four.
Thaumatrope. — An optical toy for showing the persist-
ence of an impression upon the eye after the lumi-
nous object is withdrawn, and consists of a card
having on its opposite faces figures of two differ-
ELECTRICAL DICTIONARY 281
ent objects, as a bird and a cage, and the card on
being rapidly whirled around a diameter by the
strings that hold it, the appearance presented to
the eye is that of a single picture, as the bird in the
cage.
Theater Dimmer. — A contrivance serving in theaters
to vary the intensity of the light. A choking coil.
Theater Dimming Rheostat. — A rheostat used together
with a dimmer in a theater.
Theodolite. — An instrument variously constructed, used
in trigonometrical surveying, for the accurate
measurement of horizontal and vertical angles.
Theoretical Magnet. — An imaginary magnet, assumed
to possess uniform magnetization, infinite length
and thinness. A hypothesis for the purpose of
mathematical discussion.
Therm. — A unit of heat required to raise the tempera-
ture of one gramme of water one degree, centi-
grade, starting at the temperature of its maximum
density.
Thermal. — Pertaining to heat.
Thermal Absorption. — The absorption of heat while it
is passing through a body.
Thermal Activity. — The activity which a body possesses
by reason of its heat energy. The rate at which
heat is generated. The rate at which thermal work
is done.
Thermal Circuit Closer. — A circuit closer whose oper-
ation is effected by changes of temperature.
Thermal Current. — A current resulting from the flow
of heat through a conductor.
282 ELECTRICAL DICTIONARY
Thermal Current-Strength.— The quantity of heat
which is transmitted per second across a conduct-
or's area of normal cross-section.
Thermal Equivalent of Work. — The equivalent of a
specified quantity of mechanical work in heat
units.
Thermal Resistance. — The resistance which a body of-
fers to the passage of heat through it.
Thermo-Barometer.-^An instrument by means of which
an altitude is determined by its reading of the
boiling temperature of water at such altitude. A
hysometer.
Thermo-Chemistry. — The branch of the science of chem-
istry which relates to the measurement, in thermal
units, of chemical energy.
Thermo-Electric Call. — An instrument which sounds an
alarm by means of electricity when the tempera-
ture goes above or below a certain point.
Thermo-Electricity. — Electromotive forces produced
from heat energy by direct conversion or by differ-
ences of temperature at the junction of unlike
metals.
Thermo-Magnetic Generator. — An instrument by means
of which electricity is produced under the influence
of heat and magnetism. A pyro-magnetic gener-
ator.
Thermometer, Electric. — A thermometer whose indica-
tions result from the variation of resistance in con-
ductors with variation of temperature. An instru-
ment employed to ascertain the effects of an elec-
trical discharge, and which are determined by the
movements of a liquid column, resulting from the
ELECTRICAL DICTIONARY 283
expansion of a confined body of air which the dis-
charge passes through.
Thermometric Conductivity. — The ratio of heat conduc-
tivity as determined by measurement to the specific
heat of unit volume.
Thermometry. — The science which treats of the meas-
urement of temperature.
Thermophone. — An instrument which produces sound
by means of electricity. An instrument which by
absorbing radiant energy produces sounds.
Thermostat. — An apparatus which automatically closes
an electric circuit when heated, thereby maintain-
ing a specific temperature.
Thermostatic Regulation. — The regulation of tempera-
ture obtained through the action of a thermostat.
Third-Rail Electric Railway.— i&n electric street-car
railway which employs a third rail which is insu-
lated from the track and answers for one side of
the circuit, while the outside rails, in connection
with return feeders, answer for the other side of
the circuit.
Three- Coil Armature Winding of Alternator. — An ar-
mature winding which provides for each and every
pole in the field frame, three coils in a ring arma-
ture, or three slots in a drum armature.
Three-Coil Armature Winding of Multiphase Alterna-
tor.— An armature winding which provides for
each and every pole in the field frame, three coils
in a ring armature, or three slots in a drum arma-
ture, per phase.
Three-Part Commutator. — A commutator consisting of
three insulated segments.
284 ELECTRICAL DICTIONARY
Three-Phase Armature. — An armature which has a
three-phase winding.
Three-Phase Armature Winding. — An armature wind-
ing by which it is enabled to produce three-phase
currents.
Three-Phase Bar- Winding for Armature.— A bar wind-
ing for an armature by means of which it is capable
of producing three-phase currents.
Three-Phase Circuit. — A circuit permitting the trans-
mission of three-phase currents.
Three-Phase Continuous-Current Commutating Ma-
chine.— A machine serving to transform three-
phase alternating currents to continuous currents,
using a revolving armature which has a commuta-
tor.
Three-Phase Generator. — A generator possessing the
ability to produce three-phase currents.
Three-Phase Motor. — A motor which can be operated
by three-phase currents.
Three-Phase Rotating Magnetic Field. — A rotating field
which a three-phase current produces.
Three-Phase Transformer. — Three distinct transformers
by the employment of which three-phase currents
are transformed.
Three-Point Switch. — A switch which completes a cir-
cuit through three distinct contact points.
Three- Voltmeter Method of Measurement. — A method
for the measurement of activity in alternating cur-
rent circuits and which provides for the employ-
ment of three voltmeters at the same time.
Three-Wire Circuit. — A circuit used in a three-wire sys-
tem. A three-wire diphase or triphase system.
ELECTRICAL DICTIONARY 285
Three-Wire Biphase. — A diphase circuit employing
three wires, one of which has a greater area of cross
section than the others and serves, therefore, as the
common return.
Three-Wire Meter. — A meter employed to record the
power delivered on both sides of a three-wire sys-
tem.
Three-Wire Moulding. — Moulding used in a three-wire
system of distribution.
Three-Wire Switchboard. — A switchboard adaptable for
use in a three-wire system of distribution.
Three-Wire System. — In multiple arc or constant po-
tential service, a system of distribution of electric
current consisting of three main wires which start
at the generating source and ramify with corre-
sponding diminution in size everywhere through
the lighted district; the dynamos being set in
groups of two with one lateral lead leaving the
negative binding post of one dynamo, while the
positive terminal of that dynamo connects to the
negative of the other, and the neutral lead is con-
nected between the two dynamos ; the other lateral
lead leaving at the positive binding post of the sec-
ond dynamo.
Three-Wire Transmission. — Transmission effected by
the three-wire system.
Three-Wire Telephone Switchboard. — A branch termi-
nal switchboard used in telephone operations.
Throttling. — Cutting off partly or entirely.
Throttling of Lines of Magnetic Force. — Any diminu-
tion in magnetic flux density resulting from a mag-
netic joint, or to diminution in magnetic permeabil-
ity at any section of a circuit.
286 ELECTRICAL DICTIONARY
Throw. — The deflection of a needle. Elongation.
Throw of Needle. — The angular deflection of the needle
when it makes its first move.
Throw-Over Reversing Switch. — A reversing switch
thrown from side to side in operating it.
Throw-Over Switch. — A switch serving to quickly
change a circuit from one source or system to an-
other source or system. A switch fashioned to move
about on an axis, and which can be thrown over
from one set of contacts to another.
Thunder. — The sound which follows a flash of lightning.
The report of a discharge of atmospheric electric-
ity.
Ticker. — An instrument for receiving stock quotations
and other information delivered from the instru-
ment in printing upon a paper ribbon.
Tie Wire. — A wire used to bind an insulator.
Time-Ball, Electric. — A ball which by means of electric-
ity is made to fall from an elevator position upon a
high pole ; the fall occurring exactly at noon or at
any preconcerted hour, and intended as a visual
signal by which the correct time may be made
known.
Time-Detector, Electric. — A watchman's clock actuated
by electricity and which serves to register the time
at which the watchman visits the stations on his
beat.
Time-Lag of Magnetization. — A condition suggesting
lag between the moment when the magnetizing j
force begins to act and the time of the indicated!
presence of magnetism.
Time of Vibration. — The time necessary for a back and
ELECTRICAL, DICTIONARY 287
forth motion of particles in an elastic medium to be
completed.
Time^Switch. — A switch contrived so that it will open
or close a circuit at or after the expiration of a cer-
tain time. An automatic switch so contrived that
a resistance cannot be inserted into it, nor can it
be removed from a circuit before the expiration of
a certain predetermined time.
Tinned Wire. — Wire covered with tin by the electro-
plating process.
Tinning Metal. — A solder used to join electrotype shells
or for obtaining the proper condition on their
backs preparatory to applying the backing metal.
Toll System. — A system employed in telephone service
which provides for a charge for each call made in-
stead of a specified rate of rental per annum.
Tone. — Sound, or the character of sound, or a sound
considered as of this or that character. A sound
considered as to pitch.
Toothed-Core Armature. — An armature having a lami-
nated core, the toothed disk of which has longi-
tudinal grooves on its surface, and into which the
armature coils are placed.
Toothed-Drum Armature. — A toothed-core armature
resembling a drum in shape.
Toroid.. — A solid whose surface boundary is produced
by the revolution of any closed plane about an axis
in its plane, and by which it is not cut.
Toroidal Coil. — A coil wound in the shape of a toroid.
Torque. — A force which tends to produce torsion around
an axis, as in the pulling or turning moment of an
electric motor's armature upon its shaft. The mo-
288 ELECTRICAL DICTIONARY
ment of force which causes the rotation of a dyna-
mo or other machine when applied to it. The me-
chanical, turning or rotary force whose action pro-
duces the rotation of the armature of a dynamo
electric machine or motor. The ratio, at belt or
pulley, of a motor's mechanical activity to the an-
gular velocity.
Torque Efficiency. — The relation of the torque which a
motor exerts at a specific terminal activity, to that
which would be exerted were there no loss of en-
ergy.
Torreicellian Vacuum. — The vacuum which exists above
the mercury column in the tube of a barometer;
the principle of this vacuum being applied in the
Geissler and other air pumps.
Torsion. — The twisting or wrenching of a body by the
exertion of a lateral force.
Total Candle-Power. — The total light given out by any
luminous source.
Total Resistance. — The total of a circuit's resistance.
Tower-System of Electric Lighting". — The employment
of high towers for lighting large areas; the lights
being placed at the top of the towers.
Tower Wagon. — -A wagon equipped with a skeleton
tower and tools and employed in repair work on
trolley lines; the wires being easily reached by
means of the tower.
Track Bond. — Rail bond.
Traction, Electric. — The driving of a car on any convey-
ance by means of an electric motor.
Train Describer. — An electrical instrument which indi-
cates automatically from a distance the location
ELECTRICAL DICTIONARY 289
«*
and character of railroad trains when out on the
line.
Train Wire. — A wire connected with the chief train dis-
patcher's office and used in the block system of
railroading for transmitting train orders only.
Trajectory. — /The curve described by a body thrown up-
ward obliquely in the air. A curve, which pursuant
to a given law, cuts a system of curves produced by
varying a parameter.
Trans- Continental Telephony. — Communication across
the continent by telephone.
Transfer Bus-Bar. — A bus-bar whose employment
serves to obviate a sudden variation of potential
by gradually transferring a feeder from one bus-
bar to another instead of throwing it over directly.
Transform. — To convert. To change. To change a
primary current with high initial electromotive
force into a secondary current with low initial elec-
tromotive force. To change an alternating current
into a continuous current.
Transformation of Electromotive Force or Current. —
The conversion of electric energy into another form
of energy.
Transformation of Heat.— The conversion of heat en-
ergy into another form of energy.
Transformer. — An induction coil by which a primary
current of high initial electromotive force is made
to produce a secondary current of low initial elec-
tromotive force.
Transformer Fuse. — A fuse used in either a transform-
er's primary or secondary circuit.
290 ELECTRICAL DICTIONARY
Transformer Fuse-Block. — A fuse-block inside of or
contiguous to a transformer case.
Transformer Guard. — A lightning guard used in con-
nection with a transformer. A contrivance serving
to ground the secondary of a transformer in the
event of its making accidental contact with the
primary.
Transformer Lightning-Arrester. — A style of lightning
arrester serving to protect transformers.
Transformer Motor. — An induction motor.
Transformer Stampings. — Stampings made from sheet
steel and used to build the laminated cores of trans-
formers.
Transformer Sub-Station. — A sub-station serving as a
sub-center of distribution and containing trans-
formers in groups.
Transforming. — Converting high initial electromotive
force into low initial electromotive force. Convert-
ing electric energy from lower pressure and strong-
er current to higher pressure and weaker current.
rransforming Currents. — Effecting a change in the
value of a circuit's current strength with a corre-
sponding opposite change of pressure.
Transforming Down. — Reducing the pressure in a cir-
cuit of distribution by the use of a step-down trans-
former.
Transforming Station. — Sub-station containing a num-
ber of transformers which serve to supply a collec-
tion of buildings in that location.
Transforming Up. — Increasing the pressure in a circuit
of distribution by the use of a step-up transformer.
Translucence. — Partial transparency. Transmitting
ELECTRICAL DICTIONARY 291
light, but not permitting objects to be distinctly
seen.
Translucent-Disc Photometer. — -A photometer in which
the two lights to be compared are at or opposite
to the ends of a bar scale, with a partly translucent
and partly opaque disc between them ; the intensity
of the light is then determined by the distance of
the lights from the disc when both of its surfaces
show an equal illumination.
Transmission Dynamometer. — A dynamometer which
measures and transmits the power to some machine
in distinction from one which absorbs the energy
it measures.
Transmission, Electric. — The transmission of energy
by electric currents from one point to another.
Transmission of Energy. — The transmission of energy
from one point to another.
Transmission of Electric Energy. — The transmission of
electric energy from one point to another.
Transmitted Power. — Power transmitted from one
point to another.
Transmitter, Electric. — A term embracing in its sig-
nificance the entire apparatus employed in tele-
graph or telephone systems for the transmission of
electric impulses over a line wire or conductor.
Transposing. — A method for laying metallic circuits,
serving in a telephone system to obviate the dele-
terious effects of mutual induction, and effected by
crossing equal lengths of consecutive sections of
the line alternately.
Transverse Vibration. — A vibration in which the motion
of the successive particles in an elastic medium is
292 ELECTRICAL DICTIONARY
at right angles to the progressive movement of the
wave through the medium.
Travelling Derrick. — A derrick erected on a platform
and arranged to move on guide rails, thus ena-
bling it to shift and move heavy bodies through
short distances.
Travelling Motor. — A motor mounted on a movable car
in distinction from a stationary motor.
Travelling of Arc. — The inconstancy of brilliancy in
a carbon arc resulting from a shifting of the posi-
tion of the arc between the electrodes.
Traversing Motor, Electric. — A motor operating with
a regular to-and-fro movement through a circum-
scribed distance. The motor which operates the
traverse in a crane worked by electricity.
Treated Coke Filament. — A coke filament for incan-
descent lamps which has beeen treated by the flash-
ing process.
Tree-System of Parallel Distribution. — A system of
incandescent lamp parallel distribution which may
be described by comparing the main conductors to
the trunk of a tree, and the auxiliary leads, which
run in various directions, to the branches; the
lamps occupying the position of the leaves and
twigs.
Trega. — A prefix meaning a trillion.
Tregohm. — One trillion ohms.
Trevelyan Effect. — A musical sound which under
certain conditions is emitted when a body of
heated copper is placed on thin edges supported
on a block of cold lead.
ELECTRICAL DICTIONARY 293
Triangular Triphase Winding. — Three-wire triphase
or interlinking.
Tricro. — A prefix meaning one trillionth part.
Tricro-Ampere. — The one trillionth of an ampere.
Tricrohm. — The one trillionth of an ohm.
Trigonometrical. — Pertaining to trigonometry. Per-
taining to the science of angles.
Trigonometrical Functions. — Quantities definitely re-
lated to angles taken as independed variables.
Triphase. — Three-phase.
Triphase Alternating Currents. — Three monophase
alternating currents, the phases of which are dis-
placed, with respect to one another, by one-third
of a cycle.
Triple-Pole Single-Throw Switch. — A single-throw
switch provided with three blades and designed to
close three circuits at one and the same time.
Triply Re-Entrant Armature Winding. — An armature
winding having three distinct windings, each one
being separately re-entrant.
Trolley. — A contact-wheel which rolls over the supply
wire in a trolley line and takes off the current re-
quired to operate the motor cars.
Trolley Base. — A base serving to support a trolley pole
and which is equipped with springs in order to
maintain a steady contact between the trolley and
the trolley wire; a swivel joint being, in addition
provided for reversing the direction of the trolley
pole.
Trolley Bus-Bar. — A bus-bar in a railway power station
which is connected with the trolley system in dis-
tinction to one which is connected with the ground.
294 ELECTRICAL DICTIONARY
Trolley Car. — A motor car in an electric railroad trolley
system.
Trolley Car-Controller.— A series-parallel car-control-
ler.
Trolley-Crossing. — An insulating contrivance, serving
at the crossing of two trolley wires, to enable a
trolley wheel running on one line, to cross the
other without making electrical contact. A plate
with guides, provided at the crossing of two trol-
ley wires, to aid the trolley wheel in crossing.
Trolley Wheel. — A metallic wheel fixed to the upper
end of the trolley pole, and which rolls over the
trolley wire, taking therefrom the current required
to operate the motor.
Trolley Wire. — The overhead supply wire in a trolley
system from which the current required to operate
the motor is taken by the trolley wheel.
Trolley Wire Splice. — A splice used in joining the ends
of trolley wires and effected by inserting the ends
of the two wires into a tubular conductor and then
brazing them.
True Resistance. — The true resistance measured in
ohms in distinction from counter electro-motive
force. The resistance offered by a conductor to
the passage of a current by reason of the area of
cross section and resistivity.
Trumpet, Electric. — An instrument which has a vibrat-
ing tongue and which is actuated by electricity, as
the buzzer, and adjusted in the small end of a tube
of trumpet shape.
Trunnion Screws. — A pair of screws the opposite points
of which constitute the pivots of a movable shutter,
armature or other revolving device.
ELECTRICAL DICTIONARY 295
Trunk Call. — A telephone call made through a trunk
line.
Trunk Connection. — A connection set up through a
telephone trunk wire.
Trunk-Line Wire. — Wires running through between
stations remote from each other, their ends only
being provided with transmitting and receiving
instruments. Main line telephone wires which
serve to connect two terminal offices for connec-
tion to sub-offices or subscribers. A main line tele-
phone wire serving to connect two important ter-
minals.
Trunk Wire. — A trunk line or main telephone wire. A
connecting wire extending from place to place, or
exchange to exchange, in distinction from a per-
manently connected subscriber's wire.
Tubular Electro-Magnet. — An electro-magnet resem-
bling a tube in shape.
Tubular Magnet. — A magnet with a cylindrical casing
of iron connected at one end to the core. An iron-
clad magnet.
Tumbling Box. — A box devised to rotate and employed
to polish metallic articles preparatory to electro-
plating, and which is effected by the attrition of
the objects against one another, in the box, while
the same is rotating.
Tuning of Electric Circuit. — Changing a circuit's period
or varying either the self-induction or capacity of
it in order that it may be brought into resonance
with another circuit.
Tunnel Armature. — An armature of a dynamo-electric
296 ELECTRICAL DICTIONARY
machine, with holes beneath the outer surface of
the core, into which the conductors are placed.
Turnbuckle. — A device employed to strain span wires.
v A rod, guy, or line screw tightener.
Twist System. — A method of twisting overhead wires
into a form of helical twist, as they are being run,
in order to destroy mutual inductive disturbances.
Twist in Armature Leads. — A displacement made of the
terminals of the armature leading wires, which are
connected with the segments of the commutator,
as referred to the position of the armature coils, in
order that a better position for the diameter of
commutation may be obtained, and accordingly
for the points of contact of the commutator's col-
lecting brushes.
Twisted Strip-Voltmeter. — A voltmeter which consists
of a strip of platinum-silver, twisted, and whose
operation is effected by the coiling and uncoiling
of the strip, due to variations in its temperature,
produced by the passage through it of the current
to be measured.
Twisting Force. — Torque.
Two-Circuit Armature-Winding. — An armature wind-
ing which, notwithstanding how great may be the
number of poles, provides only two circuits
through an armature between the commutator
brushes.
Two-Circuit Single-Wound Armature. — An armature
whose pitch is always forward, and which possesses
two circuits regardless of the number of poles.
Two-Layer Armature- Winding. — An armature winding
applied in two layers. A winding possessing more
ELECTRICAL DICTIONARY 297
than two layers, but which would admit of appli-
cation in two layers only.
Two-Phase Circuit. — A diphase circuit.
Two-Phase Dynamo or Generator. — A diphase gene-
rator.
Two-Phase Motor. — A diphase motor.
Two-Phase Rotary-Transformer. — A diphase rotary
transformer.
Two-Wire Incandescent Lighting. — In a system of in-
candescent lighting, the employment of a single
pair of mains, in distinction from three-wire in-
candescent lighting.
Two-Wire Moulding. — A moulding having two chan-
nels or grooves and serving to receive two-wire
mains or branches.
Two-Wire Multiple-Switchboard. — A multiple tele-
phone switchboard which has the jacks of a sub-
scriber's circuit connected by two wires.
U.
Ultra-Gaseous Matter. — Gas rarefied to such a high de-
gree that its molecules do not collide. Radiant
matter.
Ultra-Incandescent Lamp. — An incandescent lamp
whose light is increased in intensity by the radia-
tive powers of oxides of thorium, etc., with which
the filament is covered.
Ultra-Ultra- Violet. — A term for luminous frequencies
greatly beyond the violet in the spectrum.
Ultra- Violet Rays. — A term for rays the frequencies of
which exceed those of violet light.
ELECTRICAL DICTIONARY
Ultra- Violet Spectrum.— That part of the spectrum ly-
ing beyond the violet, or that part, the frequencies
of which exceed those of the violet.
Unbalanced Load. — A load whose distribution is not
symmetrical.
Unbalanced Polyphase System. — A multiphase system
wherein the distribution of the load and, conse-
quently, the pressures and currents are unsymmet-
rically distributed.
Unbuilding of Dynamo.— The loss of its charge or ex-
citation by a self-exciting dynamo.
Underground-Cable Terminal. — The point at which an
underground cable comes out of the ground. A
distributing board located at the point where an
underground cable goes into or emerges from the
ground, for the purpose of conveniently making
and changing the connections.
Underground Conductor. — An electric conductor insu-
lated and placed under the surface of the earth
and passing through the ground proper or through
conduits.
Underground Electric Conduit. — A subway for the re-
ception of electric telegraph and other conductors
under the surface, usually in the line of streets, to
dispense with telegraph poles and aerial wiring.
Underground Trolley System. — An electric trolley
system in which a plow or sled is substituted for
the trolley wheel and is drawn after or pushed
ahead of the car, thus making a contact with a
wire running inside of a slotted underground con-
duit.
Undulating Current. — An undulatory current. A cur-
ELECTRICAL DICTIONARY 299
rent whose direction is constant, but whose
strength is continuously varying.
Undulator. — A type of rotating commutator employed
on continuous-current circuits for the use of trans-
formers. A commutating device which, from a
continuous-current circuit, operates an alternating-
current apparatus.
Undulatory Currents. — Currents which change in
strength without any sudden transition from ac-
tion to inaction, as in the make and break current.
Undulatory Discharge. — A discharge the strength of
which changes gradually without any change of
direction.
Undulatory Winding. — A wave winding.
Uni-Directed Currents. — Currents which, by means of
a commutator, have been made to take the same
direction.
Uni-Directional. — Having the same direction.
Uni-Directional Discharge. — An electric discharge
whk-h follows t.hfi same direction from first to last.
Uniform Density of Field. — A field in which all equal
areas of similar cross section have the same den-
sity.
Uniform Flux. — Uniform magnetic flux.
Uniform Magnetic Field. — A field of uniform strength
in all portions — as instance the magnetic field of
the earth — -and when artificially obtained, which
cannot be definitely done, it implies great cross section
of magnet pole in proportion to the length of the
300
ELECTRICAL DICTIONARY
magnetic needle which it affects and which serves
to ascertain its uniformity.
Uniform Magnetic Flux. — A magnetic flux the density
of which is uniform.
Uniform Magnetization. — Such character of magnetiza-
tion of a bar of iron that the same quantity of
magnetic flux will traverse equal areas of normal
cross-section.
Uniform Potential. — A potential whose value is in-
variable.
Uniformly Distributed Current.— A steady current, A
current whose density in a cross-section of a con-
ductor is the same at all points.
Uniphase. — A single phase. Monophase.
Uniphase Alternator. — An alternator which produces
single-phase currents.
Unipolar. — Having one pole only.
Unipolar Armature. — An armature whose windings
continuously cut the lines of force about the one
pole, its polarity, in consequence, being unchanged
in its rotation.
Unipolar Dynamo. — A dynamo equipped with a uni-
polar armature. • A dynamo so constructed that one
portion of the conductor slides on or around the
magnet in consequence of which it cuts lines of
force always near the same pole of the magnet. A
dynamo with one field magnet.
Unipolar Magnet. — A proposed term for a poised or
suspended magnet one of whose poles lies in the
axis of suspension.
Unit of Acceleration. — An acceleration which imparts
ELECTRICAL DICTIONARY 301
unit velocity in unit time to a body ; for instance :
the centimetre-second.
Unit of Activity. — A rate-of-doing work equal to one
unit of work in each second. An activity of one
erg per second in the C. G. S. system and the Watt
in the practical system.
Unit of Electric Quantity. — The coulomb in the unit
practical system. A quantity of electricity trans-
mitted by a unit of current per second.
Unit of Electric Supply. — A unit whose value would
be represented by the flowing for one hour of one
thousand amperes under an electro-motive force
of one volt and which was adopted for present
needs by the Board of Trade in England. Electric
energy equal to 3,600,000 joules. One Kilowatt-
hour.
Unit of Electric Work.— The joule.
Unit of Electrostatic Capacity. — That capacity of a con-
ductor or condenser which admits of its being
charged with a quantity of electricity equal to
one coulomb by an electro-motive force of one volt.
Unit of Force. — The fundamental or C. G. S. unit of
force, which is the dyne. A force which can im-
part an acceleration of one centimetre-per-second
to a mass of one gramme per second.
Unit of Heat. — The British unit of heat or the pound-
degree Fahrenheit, which is the quantity of heat
required to raise the temperature of a pound of
water from 32 deg. to 33 deg. Fahr. The C. G. S.
unit is the gramme-degree centigrade; another
metric unit is the kilogramme centigrade; the lat-
ter being termed the calorie, and the former the
302 ELECTRICAL DICTIONARY
joule; the term joule being applied to a quantity
of heat equivalent to the energy of a Watt-second
or volt-coulomb; equal to .241 gramme-degree
calorie.
Unit of Illumination. — The lux.
Unit of Magnetic Flux. — The quantity of flux which
will pass through a magnetic circuit the reluctance
of which is one oersted, under a magneto-motive
force of one gilbert.
Unit of Magnetic Intensity. — The intensity of a field
of 108 C. G. S. The gauss.
Unit of Magneto-Motive Force. — A force equal to 0.7958
ampere-hour. The gilbert. That magneto-motive
force which is necessary to cause one unit of flux
to pass through a circuit against a magnetic re-
sistance of an oersted.
Unit of Output of Dynamo-Electric Machine. — The unit
of electric force supplied by the current of a
dynamo-electric machine. The kilowatt.
Unit of Photometric Intensity. — The intensity of light
that a candle which consumes 2 grains of sperm
wax per minute will produce; the candle being of
specified composition and dimensions.
Unit of Resistance. — The original ohm, so termed pre-
. vious to 1884. A resistance which requires unit
difference of potential to cause the passage of unit
current strength through it.
Unit Strength of Current. — The ampere in the practical
system of units and ten amperes in the C. G. S.
system of units. A strength of current which will
exert a force of one dyne on a unit magnetic pole
when the current is passed through a circuit one
ELECTRICAL DICTIONARY 303
centimetre in length arranged in an arc of a circle
one centimetre in radius, the pole being placed in
the center of the arc.
Units of Work. — The unit of energy or the erg, the cor-
relative of which is work and which is opposite to
and equal to the energy expended in its accomplish-
ment.
Universal Ether. — The ether supposed to exist every-
where in space.
Unmarked End of Magnet. — A term by which the south-
seeking pole of the magnet was once known.
Unmarked Pole of Magnet. — A magnet's south-seeking
pole.
Unmarked Magnet Pole. — A name signifying a mag-
net's south pole.
Unvarying Current. — A current whose strength does
not vary.
Uranium Rays. — Becquerel rays.
Useful Life of Incandescent Lamp. — The length of time
during which an incandescent lamp performs effi-
cient duty.
V.
Vacuum. — A space empty or void of all matter. A
space from which all gas has been exhausted.
Vacuum Pump. — An air pump.
Vacuum-Tube Lighting. — Illumination artificially ob-
tained by passing electric charges through vacuum
tubes.
Vacuum Tubes. — Tubes of glass through which electric
discharges are passed after the gases have been
304 ELECTRICAL DICTIONARY
partially removed, thereby obtaining luminous ef-
fects— Koentgen's, Crookes' and other high vac-
uum tubes.
Valency. — The relative power of replacing hydrogen
or combining therewith, possessed by different ele-
ments.
Vapor. — Any substance in the gaseous or aeriform state
the condition of which is ordinarily that of a liquid
or solid.
Vapor Globe of Incandescent Lamp. — A glass globe by
which the chamber of an incandescent lamp is sur-
rounded, which enables the lamp to be used in
places where it is exposed to water or to be used
in an explosive atmosphere.
Vapor Pressure. — The pressure at which liquids va-
porize.
Vaporization. — The act of vaporizing or the state of
being converted into vapor. The artificial forma-
tion of vapor.
Variable Resistance. — A resistance whose value is capa-
ble of being varied or changed. Adjustable re-
sistance.
Variation of Declination. — A variation, at any place,
of the earth's magnetic declination.
Variometer. — An instrument employed to determine
the relative values of the horizontal component of
the earth's magnetic field in different places.
Var ley's Photometer. — A style of photometer which de-
termines the intensity of the light to be measured
from the relative openings of two concentric cir-
cular diaphragms introduced into two discs which
ELECTRICAL DICTIONARY 305
revolve ; the standard light and that which is to
be measured, passing respectively through them.
Vector. — A quantity which has both magnitude and
direction.
Vector Diagram. — A diagram which shows the relations
of vector quantities.
Vector Equations. — Equations which connect vector
quantities.
Vector Potential. — A potential which has both magni-
tude and direction.
Velocity. — Rate of motion. The relation of motion to
time, measured by the number of units of space
passed over by the moving body in a unit of time ;
usually the number of feet in a second.
Velocity of Discharge. — The velocity of an escaping
gas or liquid from an opening in a specified time.
The time consumed by a discharge in passing from
a specified length of conductor.
Velocity Ratio. — A term applied to the ratios existing
between the electrostatic and electro-magnetic
units. The relation between the velocities of two
reciprocal parts of a machine.
Ventilated Armature- Windings. — Armature windings
so constructed as to be readily cooled by driving
currents of air over them.
Ventilation of Armature of Dynamo or Motor. — Ven-
tilation of the armature by means of air supplied
through apertures in it and which is provided for
in order to obviate too great a rise in temperature
during the operation of the machine.
Vernier. — A short scale made to slide along the divi-
sions of a graduated instrument for indicating
306 ELECTRICAL DICTIONARY
parts of divisions, as the limb of a sextant or the
scale of a barometer.
Vernier Caliper. — A vernier provided with a vernier
scale to insure greater exactness in observation.
Vernier Wire-Gauge. — A micrometer wire gauge.
Vibrating Contact. — A spring contact which automati-
cally opens and closes a circuit by being connected
with one part of the circuit in such manner as to
enable it to vibrate towards and from another part
of the circuit.
Vibration. — Quick motion to and fro. Oscillation as of
a pendulum or musical cord.
Vibration Frequency. — The number of vibrations per
second.
Virgin Iron. — Iron which has never been magnetized.
Viscous Hysteresis. — The creeping up by degrees of
magnetization upon the application of a magnetic
force with positive steadiness to a bar of iron, and
which may equal several per -cent of the total mag-
netization, and continue in effect for half hour or
so. The true magnetic lag.
Vis- Viva. — The kinetic energy of a moving body. Me-
chanical energy.
Vitreous. — Pertaining to glass.
Volatilization Electric. — The superficial sublimation or
evaporation of a substance under the influence of
negative electricity.
Volt. — The practical unit of electro-motive force or
difference of potential. An electro-motive force
which would cause a current of one ampere to flow
through a resistance of one ohm. The electro-
motive force induced in a conductor by its cutting
ELECTRICAL DICTIONARY 307
100,000,000 lines of force per second. Such a rise
of potential as would be produced by charging a
condenser of one farad capacity with one coulomb.
An electro-motive force equal to 10s absolute elec-
tro-magnetic units, or to the one-three-hundredth
electrostatic unit.
Volt-Ammeter. — A term applied to an instrument which
can measure either or both volts and amperes in
a circuit.
Volt-Ampere.— The watt.
Voltage. — -Potential difference or electro-motive force
expressed in volts.
Voltaic Arc. — The brilliant arc between two carbon
electrodes barely separated, caused by a current of
adequate strength and involving adequate poten-
tial difference; the pencils of carbon forming ter-
minals in the circuit; being first placed in contact
and then slightly separated.
Voltaic Cell. — Two metals or a metal and a metalloid
which when combined and immersed in electrolytes
and connected by a conductor will generate elec-
tricity.
Voltaic Effect. — The potential difference developed by
contact of unlike conducting metals.
Voltameter. — An apparatus employed to determine the
quantity of electricity flowing through a conduc-
tor by measuring its electrolytic action.
Vulcabeston. — An insulating material composed of rub-
ber and asbestos.
Vulcanite. — Vulcanized india rubber, valuable for its
high insulating properties and specific inductive
capability.
308 ELECTRICAL DICTIONARY
Vulcanized Fibre. — An insulating material used where
the highest insulation is required.
Vulcanizing Wooden Poles. — Confining wooden poles in
a tight cylinder and then subjecting them to the
action of heat.
W.
Wall Bracket. — An insulator bracket fastened to the
wall.
Wall Set. — Telephone apparatus set against a wall.
Wall Socket. — A socket for an incandescent lamp de-
signed to be attached to a wall.
Wandering of Electric Spark. — A brilliant globule pro-
duced by a discharge, and which moves in a slow
and irregular manner over the surface of the tin
foil in a condenser to which the terminals of a
rheostatic machine are placed, when a perforation
accidentally happens to the mica plate in the con-
denser.
Waste Magnetic Field. — A stray field.
Watch-Case Telephone Receiver. — A small telephone
receiver resembling a watch case.
Watchman's Electric Register. — A style of recorder
which makes a permanent record of the visits of
a watchman to the different portions of his beat
at stated intervals.
Water-Cooled Transformer. — A transformer cooled by
means of water being forced through or around it.
Water Horse-Power. — A horse power which falling
water develops and equal to about 15 cubic feet
of water falling through a distance of one foot per
second.
ELECTRICAL DICTIONARY 309
Water-Level Alarm, Electric. — An electrically sounded
alarm when a change of water level takes place in
a tank or boiler.
Water-Pipe Resistance. — A resistance offered by any
pipe to the water flowing through it.
Water-Proof Wire. — Wire encased in water-proof covr
ering.
Water Pyrometer. — A pyrometer which determines the
temperature of a furnace or other source of in-
tense heat by exposing a metal cylinder of a speci-
fied weight to the source of heat for a specified
time and then placing the cylinder into a known
weight of water and noting the increase of tem-
perature in the water.
Water Rheostat. — A rheostat the resistance of which is
determined by means of a quantity of water of
fixed dimensions.
Watt. — The practical unit of electric activity, rate of
work or rate of energy. The power is equivalent
to 44.25 foot-pounds of work done in a minute, or
0.7375 foot-pound of work done in a second.
Watt Arc. — A voltaic arc whose electric power is reck-
oned in watts.
Watt-Hour. — A unit of electric energy or work. One
watt exerted or expended for one hour.
Wattmeter. — An instrument serving to measure the
power of a circuit.
Wave Winding. — A winding which resembles a wave
in form. Continuous or undulatory winding.
Weber. — The practical unit of magnetic flux. A name
suggested by Clausius and Siemens to denote a
310 ELECTRICAL DICTIONARY
magnet pole of unit strength; but the use of the
term has been abandoned.
Weber's Theory of Diamagnetism. — A theory which as-
sumes originally magnetized atoms in order to
account for diamagnetism.
Weight Efficiency of Transformer.— A transformer's
specific activity.
Welding. — Uniting metals at a high temperature and
leaving no trace of a junction.
Welding Converter. — A transformer used to step down
an alternating current which is used for the pur-
pose of fusing or welding metals together.
Welding, Electric. — Welding by the use of heat electri-
cally generated.
Welding Transformer. — A step-down transformer used
in electric welding.
Welsbach Burner. — A mantle covered with refractory
material whose light is due toancandescence under
the action of a Bunsen flame.
Western Union Splice. — An American wire joint.
Wheatstone's Electric Balance. — An electric bridge or
balance.
Wheatstone's Bridge. — A Wheatstone's electric bal-
ance.
Whistling Effect. — In a carbon transmitter and tele-
phone receiver in a line, an effect produced when
the transmitter, being close to the receiver is
slightly jarred, resulting in the emission of a musi-
cal sound by the receiver and which reacts upon
the transmitter, producing similar sounds in other
receivers on the same circuit.
ELECTRICAL DICTIONARY 311
White Heat. — That temperature of a heated body at
which it glows with a white heat.
Wind, Electric. — A rush of air atoms from a point con-
nected to a condenser statically charged.
Windings. — The coils put on the armature of a dynamo
or motor or on an electro-magnet's core.
Wipe Spark. — A spark emitted from a spark coil pro-
duced by the wiping contact of a spring.
Wiped Joint. — A plumber's joint. A joint formed in
the lead sheathing of a cable by applying free
metal to the surfaces as done by plumbers.
Wiping Contact. — The contact made by one conductor
wiping against another.
Wire Splice. — A splice made between two lengths of
wire.
Wire Terminals. — Eyes of metal suitable to solder to
the ends of wires for switchboard connections.
Wire-Wound Armature. — -An armature whose windings
consist of wire in distinction to one wound with
bars.
Wireless Telegraphy. — A term meaning any system of
telegraphic communication which can be carried
on without circuits composed of wires.
Wiring. — Placing wires in a circuit. All of the electric
conductors employed in an electric distribution cir-
cuit referred to collectively.
Work. — The action of a force through space against
resistance.
Woven-Wire Dynamo or Motor Brushes. — Brushes
made of gauze for dynamos or motors.
312 ELECTRICAL DICTIONARY
X-Ray Lamp. — A high vacuum tube lamp whose in-
terior walls are covered with crystals of calcium
or other fluorescent substances and which when
exposed to X-Rays gives out light.
X-Ray Photograph. — A term signifying radiograph.
X-Ray Transformer. — A transformer serving to obtain
the high potential discharges used in X-ray tubes.
X-Rays. — A curious kind of radiation discovered by
and named after Roentgen, the exact nature of
which is not yet known. Rays which readily pene-
trate and pass through divers substances; causing
fluorescence in certain bodies and producing on
photographic plates an actinic effect; causing the
discharge of an insulated charged conductor, and
producing a troublesome affection of the skin when
exposed to the rays too long.
Y.
Y-Connection of Three-Phaser.— Star connection. The
connection of a triphaser's three circuits to the
.same junction, and resembling the letter Y in ap-
pearance.
Y-Connected Three-Phaser Armature. — A triphase arm-
ature with three circuits connected in common to
one point.
Y-Current. — A current in a triphase system between
any wire and the neutral point.
Y-Potential of Triphase System. — In a triphase system,
the effective difference of potential or voltmeter
ELECTRICAL DICTIONARY 313
pressure between one terminal or conductor and
the neutral point.
Yoke. — The piece of iron in an electro-magnet which
connects the ends most remote from the poles of
the two parts of the core where the wire has been
wound.
Z.
Zinc-Battery. — A battery which decomposes zinc in an
electrolyte, thereby producing a current.
Zinc-Carbon Voltaic Cell. — A voltaic cell consisting of
a suitable electrolyte into which is immersed a
zinc-carbon couple.
Zinc Currents. — Negative currents.
Zinc-Lead Accumulator. — A secondary cell in which
are used lead and zinc plates.
Zinc Plating. — The employment of zinc in electro-plat-
ing.
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