The Standard Electrical Dictionary / A Popular Dictionary of Words and Terms Used in the Practice of Electrical Engineering

by T. O'Conor Sloane

FIG. 108. DECLINATION COMPASS.
Compass, Inclination.
A magnetic needle mounted on a horizontal axis at its centre of gravity,
so as to be free to assume the dip, or magnetic inclination, when placed
in the magnetic meridian. It moves over the face of a vertical graduated
circle, and the frame also carries a spirit level and graduated
horizontal circle. In use the frame is turned until the needle is
vertical. Then the axis of suspension of the needle is in the magnetic
meridian. The vertical circle is then turned through 90° of the horizon,
which brings the plane of rotation of the needle into the magnetic
meridian, when it assumes the inclination of the place.
143 STANDARD ELECTRICAL DICTIONARY.
Compass, Mariner's.
A compass distinguished by the card being attached to and rotating with
the needle. A mark, the "lubber's mark" of the sailors is made upon the
case. This is placed so that the line connecting it, and the axis of
rotation of the card is exactly in a plane, passing through the keel of
the ship. Thus however the ship may be going, the point of the card
under or in line with the "lubber's mark," shows how the ship is
pointing. The case of the mariner's compass is often bowl-shaped and
mounted in gimbals, a species of universal joint, so as to bc always
horizontal. (See Compass, Spirit-Gimbals.)

FIG. 109. MARINER'S COMPASS.
Compass, Points of the.
The circle of the horizon may bc and is best referred to angular
degrees. It has also been divided into thirty-two equiangular and named
points. A point is 11.25°. The names of the points are as follows:
North, North by East, North North-east, North-east by North, North-east,
North-east by East, East North-east, East by North, East, East by South,
East South-east, South-east by East, South-east, South-east by South,
South South-east, South by East, South, South by West, South South-west,
South-west by South, South-west, South-west by West, West South-west,
West by South, West, West by North, West North-west, North-west by West,
North-west, North West by North, North North-west, North by West. They
are indicated by their initials as N. N. W., North North-west, N. by W.,
North by West.
Compass, Spirit.
A form of mariner's compass. The bowl or case is hermetically sealed and
filled with alcohol or other nonfreezing liquid. The compass card is
made with hollow compartments so as nearly to float. In this way the
friction of the pivot or point of support is greatly diminished, and the
compass is far more sensitive.
Compass, Surveyor's.
A species of theodolite; a telescope with collimation lines, mounted
above a compass, so as to be applicable for magnetic surveys. Its use is
to be discouraged on account of the inaccuracy and changes in
declination of the magnetic needle.
144 STANDARD ELECTRICAL DICTIONARY.
Compensating Resistances.
In using a galvanometer shunt the total resistance of the circuit is
diminished so that in some cases too much current flows through it; in
such case additional resistance, termed as above, is sometimes
introduced in series. The shunt in parallel with the galvanometer is
thus compensated for, and the experimental or trial circuit does not
take too much current.
Complementary Distribution.
Every distribution of electricity has somewhere a corresponding
distribution, exactly equal to it of opposite electricity; the latter is
the complimentary distribution to the first, and the first distribution
is also complimentary to it.
Component.
A force may always be represented diagrammatically by a straight line,
terminating in an arrow-head to indicate the direction, and of length to
represent the intensity of the force. The line may always be assumed to
represent the diagonal of a parallelogram, two of whose sides are
represented by lines starting from the base of the arrow, and of length
fixed by the condition that the original force shall be the diagonal of
the parallelogram of which they are two contiguous sides; such lines are
called components, and actually represent forces into which the original
force may always be resolved. The components can have any direction.
Thus the vertical component of a horizontal force is zero; its
horizontal component is equal to itself. Its 450 component is equal to
the square root of one-half of its square.
Condenser.
An appliance for storing up electrostatic charges: it is also called a
static accumulator. The telegraphic condenser consists of a box packed
full of sheets of tinfoil. Between every two sheets is a sheet of
paraffined paper, or of mica. The alternate sheets of tinfoil are
connected together, and each set has its own binding post. (See
Accumulator, Electrostatic.)
Condenser, Sliding.
An apparatus representing a Leyden jar whose coatings can be slid past
each other. This diminishes or increases the facing area, and
consequently in almost exactly similar ratio diminishes or increases the
capacity of the condenser.
Conductance.
The conducting power of a given mass of specified material of specified
shape and connections. Conductance varies in cylindrical or prismatic
conductors, inversely as the length, directly as the cross-section, and
with the conductivity of the material. Conductance is an attribute of
any specified conductor, and refers to its shape, length and other
factors. Conductivity is an attribute of any specified material without
direct reference to its shape, or other factors.
Conduction.
The process or act of conducting a current.
145 STANDARD ELECTRICAL DICTIONARY.
Conductivity.
The relative power of conducting the electric current possessed by
different substances. A path for the current through the ether is opened
by the presence of a body of proper quality, and this quality, probably
correlated to opacity, is termed conductivity. There is no perfect
conductor, all offer some resistance, q. v., and there is hardly any
perfect non-conductor. It is the reverse and reciprocal of resistance.
Conductivity, Specific.
The reciprocal of specific resistance. (See Resistance--Specific.)
Conductivity, Unit of.
The reciprocal of the ohm; it is a more logical unit, but has never been
generally adopted; as a name the title mho (or ohm written backwards)
has been suggested by Sir William Thomson, and provisionally adopted.
Conductivity, Variable.
The conductivity for electric currents of conductors varies with their
temperature, with varying magnetization, tension, torsion and
compression.
Conductor.
In electricity, anything that permits the passage of an electric
current. Any disturbance in the ether takes the form of waves because
the ether has restitutive force or elasticity. In a conductor, on the
other hand, this force is wanting; it opens a path through the ether and
a disturbance advances through it from end to end with a wave front, but
with no succession of waves. This advance is the beginning of what is
termed a current. It is, by some theorists, attributed to impulses given
at all points along the conductor through the surrounding ether, so that
a current is not merely due to an end thrust. If ether waves preclude a
current on account of their restitutive force, ether waves cannot be
maintained in a conductor, hence conductors should be opaque to light,
for the latter is due to ether waves. This is one of the more practical
every day facts brought out in Clerk Maxwell's electromagnetic theory of
light. The term conductor is a relative one, as except a vacuum there is
probably no substance that has not some conducting power. For relative
conducting power, tables of conductivity, q. v., should be consulted.
The metals beginning with silver are the best conductors, glass is one
of the worst.
[Transcriber's note: See "ether" for contemporary comments on this now
discarded concept.]
Conductor, Anti-Induction.
A current conductor arranged to avoid induction from other lines. Many
kinds have been invented and made the subject of patents. A fair
approximation may be attained by using a through metallic circuit and
twisting the wires composing it around each other. Sometimes concentric
conductors, one a wire and the other a tube, are used, insulated, one
acting as return circuit for the other.
Conductor, Conical.
A prime conductor of approximately conical shape, but rounded on all
points and angles. Its potential is highest at the point.
146 STANDARD ELECTRICAL DICTIONARY.
Conductor, Imbricated.
A conductor used in dynamo armatures for avoiding eddy currents, made by
twisting together two or more strips of copper.
Conductor, Prime.
A body often cylindrical or spherical in shape, in any case with no
points or angles, but rounded everywhere, whose surface, if the
conductor itself is not metallic, is made conducting by tinfoil or gold
leaf pasted over it. It is supported on an insulating stand and is used
to collect or receive and retain static charges of electricity.
Conductors, Equivalent.
Conductors of identical resistance. The quotient of the length divided
by the product of the conductivity and cross-section must be the same in
each, if each is of uniform diameter.
Conjugate. adj.
Conjugate coils or conductors are coils placed in such relation that the
lines of force established by one do not pass through the coils of the
other. Hence variations of current in one produce no induced currents in
the other.
Connect. v.
To bring two ends of a conductor together, or to bring one end of a
conductor in connection with another, or in any way to bring about an
electrical connection.
Connector.
A sleeve with screws or other equivalent device for securing the ends of
wires in electrical contact. A binding-post, q. v., is an example.
Sometimes wire spring-catches are used, the general idea being a device
that enables wires to be connected or released at will without breaking
off or marring their ends. The latter troubles result from twisting
wires together.
Consequent Poles.
A bar magnet is often purposely or accidentally magnetized so as to have
both ends of the same polarity, and the center of opposite polarity. The
center is said to comprise two consequent poles. (See Magnet,
Anomalous.)
Conservation of Electricity.
As every charge of electricity has its equal and opposite charge
somewhere, near or far, more or less distributed, the sum of negative is
equal always to the sum of positive electrical charges. For this
doctrine the above title was proposed by Lippman.
Contact Breaker.
Any contrivance for closing a circuit, and generally for opening and
closing in quick succession. An old and primitive form consisted of a
very coarsely cut file. This was connected to one terminal, and the
other terminal was drawn over its face, making and breaking contact as
it jumped from tooth to tooth. (See Circuit Breaker--do. Automatic,
etc.--do. Wheel-do. Pendulum.)
147 STANDARD ELECTRICAL DICTIONARY.
Contact, Electric.
A contact between two conductors, such that a current can flow through
it. It may be brought about by simple touch or impact between the ends
or terminals of a circuit, sometimes called a dotting contact, or by a
sliding or rubbing of one terminal on another, or by a wheel rolling on
a surface, the wheel and surface representing the two terminals.
There are various descriptions of contact, whose names are
self-explanatory. The term is applied to telegraph line faults also, and
under this, includes different descriptions of contact with neighboring
lines, or with the earth.
Contact Electricity.
When two dissimilar substances are touched they assume different
electric potentials. If conductors, their entire surfaces are affected;
if dielectrics, only the surfaces which touch each other. (See Contact
Theory.)
Contact Faults.
A class of faults often called contacts, due to contact of the conductor
of a circuit with another conductor. A full or metallic contact is where
practically perfect contact is established; a partial contact and
intermittent contact are self-explanatory.
Contact Point.
A point, pin or stud, often of platinum, arranged to come in contact
with a contact spring, q. v., or another contact point or surface, under
any determined conditions.
Contact Potential Difference.
The potential difference established by the contact of two dissimilar
substances according to the contact theory, q. v.
Contact Series.
An arrangement or tabulation of substances in pairs, each intermediate
substance appearing in two pairs, as the last member of the first, and
first member of the succeeding pair, with the statement of the potential
difference due to their contact, the positively electrified substance
coming first. The following table of some contact potentials is due to
Ayrton and Perry:
CONTACT SERIES.
Difference of Potential in Volts.
Zinc--Lead .210
Lead--Tin .069
Tin--Iron .313
Iron--Copper .146
Copper--Platinum .238
Platinum-Carbon .113
The sum of these differences is 1.089, which is the contact potential
between zinc and carbon.
Volta's Law refers to this and states that--
The difference of potential produced by the contact of any two
substances is equal to the sum of the differences of potentials
between the intervening substances in the contact series.
It is to be remarked that the law should no longer be restricted to or
stated only for metals.
148 STANDARD ELECTRICAL DICTIONARY.
Contact-spring.
A spring connected to one lead of an electric circuit, arranged to press
against another spring, or contact point, q. v., under any conditions
determined by the construction of the apparatus. (See Bell,
Electric--Coil, Induction.)
Contact Theory.
A theory devised to explain electrification, the charging of bodies by
friction, or rubbing, and the production of current by the voltaic
battery. It holds that two bodies, by mere contact become oppositely
electrified. If such contact is increased in extent by rubbing together,
the intensity of their electrification is increased. This
electrification is accounted for by the assumption of different kinetic
energy, or energy of molecular motion, possessed by the two bodies;
there being a loss and gain of energy, on the two sides respectively,
the opposite electrifications are the result. Then when separated, the
two bodies come apart oppositely electrified.
The above accounts for the frictional production of electricity. In the
voltaic battery, a separation of the atoms of hydrogen and oxygen, and
their consolidation into molecules occurs, and to such separation and
the opposite electrification of the electrodes by the oxygen and
hydrogen, the current is attributed, because the hydrogen goes to one
electrode, and the oxygen to the other, each giving up or sharing its
own charge with the electrodes to which it goes. If zinc is touched to
copper, the zinc is positively and the copper negatively electrified. In
the separation of hydrogen and oxygen, the hydrogen is positively and
the oxygen negatively electrified. In the battery, the current is due to
the higher contact difference of oxygen and hydrogen compared to that
between zinc and copper. It will be seen that the two contact actions in
a battery work against each other, and that the current is due to a
differential contact action. The zinc in a battery is electrified
negatively because the negative electrification of the oxygen is greater
in amount than its own positive electrification due to contact with the
copper.
Contractures.
A muscular spasm or tetanus due to the passage of a current of
electricity; a term in electro-therapeutics.
Controlling Field.
The magnetic or electro-magnetic field, which is used in galvanometers
to control the magnetic needle, tending to restore it to a definite
position whenever it is turned therefrom. It may be the earth's field or
one artificially produced.
Controlling Force.
In galvanometers and similar instruments, the force used to bring the
needle or indicator back to zero. (See Controlling
Field--Electro-Magnetic Control--Gravity Control--Magnetic
Control--Spring Control.)
149 STANDARD ELECTRICAL DICTIONARY.
Convection, Electric.
The production of blasts or currents of air (convection streams) from
points connected to statically charged conductors. The term is sometimes
applied to electric convection of heat. (See Convection of Heat,
Electric.)
Convection, Electrolytic.
The resistance of acidulated water as a true conductor is known to be
very, almost immeasurably, high. As an electrolytic, its resistance is
very much lower. Hence the current produced between immersed electrodes
is theoretically almost null, unless the difference of potential between
them is high enough to decompose the liquid. Yet a feeble current too
great for a true conduction current is sometimes observed when two
electrodes with potential difference too low to cause decomposition are
immersed in it. Such a current is termed an electrolytic convection
current. It is supposed to be due to various causes. Some attribute it
to the presence of free oxygen from the air, dissolved in the water with
which the hydrogen combines. Others attribute it to the diffusion of the
gases of decomposition in the solution; others assume a partial
polarization of the molecules without decomposition. Other theories are
given, all of which are unsatisfactory. The term is due to Helmholtz.
Convection of Heat, Electric.
The effect of a current upon the distribution of heat in an unevenly
heated conductor. In some, such as copper, the current tends to equalize
the varying temperatures; the convection is then said to be positive, as
comparable to that of water flowing through an unequally heated tube. In
others, such as platinum or iron, it is negative, making the heated
parts hotter, and the cooler parts relatively cooler.
The effect of the electric current in affecting the distribution of heat
in unequally heated metal (Thomson's effect. q. v.), is sometimes so
termed. If a current passes through unequally heated iron it tends to
increase the difference of temperature, and the convection is negative;
in copper it tends to equalize the temperature, and the convection is
positive.
Converter.
An induction coil used with the alternating current for changing
potential difference and inversely therewith the available current. They
generally lower the potential, and increase the current, and are placed
between the primary high potential system that connects the houses with
the central station, and the secondary low potential system within the
houses. A converter consists of a core of thin iron sheets, wound with a
fine primary coil of many convolutions, and a coarse secondary coil of
few convolutions. The ratio of convolutions gives the ratio of maximum
potential differences of their terminals between the primary and
secondary coils. The coil may be jacketed with iron to increase the
permeance. (See Alternating Current System.)

Fig. 110. FERRANTI'S CONVERTER OR TRANSFORMER.

Fig. 111. SWINBURNE'S HEDGEHOG TRANSFORMER.
150 STANDARD ELECTRICAL DICTIONARY.
Co-ordinates, System of.
A system for indicating the position of points in space by reference to
fixed lines, intersecting at a determined and arbitrary point 0, termed
the origin of co-ordinates. In plane rectangular co-ordinates two lines
are drawn through the origin, one horizontal, termed the axis of
abscissas, or axis of X. All distances measured parallel to it, if
unknown, are indicated by x, and are termed abscissas. The other axis is
vertical, and is termed the axis of ordinates, or axis of Y. All
distances measured parallel to it, if unknown, are indicated by y and
are termed ordinates. Thus by naming its abscissa and ordinate a point
has its position with reference to the axes determined, and by
indicating the relation between a point, line or curve, and a system of
abscissas and ordinates, the properties of a line or curve can be
expressed algebraically. Co-ordinates may also be inclined to each other
at any other angles, forming oblique co-ordinates; relations may be
expressed partly in angles referred to the origin as a centre, giving
polar co-ordinates. For solid geometry or calculations in three
dimensions, a third axis, or axis of Z, is used, distances parallel to
which if unknown are indicated by z.

Fig. 112. AXES OF CO-ORDINATES.
151 STANDARD ELECTRICAL DICTIONARY.
Cooling Box.
In a hydroelectric machine, q. v., a conduit or chest through which the
steam passes on its way to the nozzles. Its object is to partially
condense the steam so as to charge it with water vesicles whose friction
against the sides of the nozzles produces the electrification .
152 STANDARD ELECTRICAL DICTIONARY.
Copper.
A metal; one of the elements. Symbol, Cu; atomic weight, 63.5;
equivalent, 63.5 and 31.75; valency, 1 and 2; specific gravity, 8.96.
It is a conductor of electricity, whose conductivity is liable to
vary greatly on account of impurities.
Annealed. Hard drawn.
Relative resistance (Silver = 1), 1.063 1.086
Specific resistance, 1.598 1.634 microhms.
Resistance of a wire at 0° C. (32° F.),
Annealed. Hard Drawn.
(a) 1 foot long, weighing 1 grain, .2041 ohms .2083 ohms.
(b) 1 foot long, 1/1000 inch thick, 9.612 " 9.831 "
(c) 1 meter long, weighing 1 gram, .1424 " .1453 "
(d) 1 meter long, 1 millimeter thick, .02034 " .02081 "
microhm. microhm.
Resistance of 1 inch cube at 0°C. (32° F.) .6292 .6433
Percentage of resistance change,
per 1° C. (1.8° F.) at about 20° C. (68° F.) = 0.388 per cent.
Electro-chemical Equivalent (Hydrogen = .0105) Cuprous .6667
Cupric .3334
In electricity it has been very extensively used as the negative plate
of voltaic batteries. It has its most extensive application as
conductors for all classes of electrical leads.
Copper Bath.
A solution of copper used for depositing the metal in the electroplating
process. For some metals, such as zinc or iron, which decompose copper
sulphate solution, special baths have to be used.
The regular bath for copper plating is the following:
To water acidulated with 8 to 10 percent. of sulphuric acid as much
copper sulphate is added as it will take up at the ordinary temperature.
The saturated bath should have a density of 1.21. It is used cold and is
kept in condition by the use of copper anodes, or fresh crystals may be
added from time to time.
For deposition on zinc, iron, tin and other metals more electropositive
than copper, the following baths may be used, expressed in parts by
weight:
Tin
Iron and Steel. Cast Iron
Cold Hot. and Zinc. Zinc.
Sodium Bisulphate, 500 200 300 100
Potassium Cyanide, 500 700 500 700
Sodium Carbonate, 1000 500 --- ---
Copper Acetate, 475 500 350 450
Aqua Ammoniae, 350 300 200 150
Water, 2500 2500 2500 2500
These are due to Roseleur.
153 STANDARD ELECTRICAL DICTIONARY.
Copper Stripping Bath.
There is generally no object in stripping copper from objects. It can be
done with any of the regular copper baths using the objects to be
stripped as anode. The danger of dissolving the base itself and thereby
injuring the article and spoiling the bath is obvious.
Cord Adjuster.
A device for shortening or lengthening the flexible cord, or flexible
wire supplying the current, and by which an incandescent lamp is
suspended. It often is merely a little block of wood perforated with two
holes through which the wires pass, and in which they are retained in
any desired position by friction and their own stiffness.