55  STANDARD ELECTRICAL DICTIONARY.


B.
(a) Abbreviation for BaumÉ, a hydrometer scale. (See BaumÉ.) Thus 10º B.
means "ten degrees BaumÉ."

(b) Symbol for the coefficient of induced magnetization, or the number
of lines per square centimeter induced in a magnetic circuit or in any
specified part of it.


B. A.
Abbreviation for British Association. It is prefixed to standards fixed
by the committee of the British Association for the Advancement of
Science. Thus the B. A. ohm means the British Association ohm, a measure
of resistance which is equal to the resistance of a column of mercury
104.9 centimeters long and one square millimeter area of cross-section.
(See Ohm.)


Back Induction.
A demagnetizing force produced in a dynamo armature when a lead is given
the brushes. The windings by such setting of the brushes are virtually
divided into two sets, one a direct magnetizing set, the other a cross
magnetizing set. The latter have a component due to the obliqueness of
the neutral line, which component is demagnetizing in its action.


Back Shock or Stroke of Lightning.
A lightning stroke received after the main discharge of the lightning,
and caused by a charge induced in neighboring surfaces by the main
discharge. The discharge affects the evenness of distribution of
surrounding surfaces so that a species of secondary discharge is
required to make even the distribution, or to supply charge where needed
to bind an opposite one. The effects are much lese severe as a rule than
those of the main charge, although the back stroke has caused death. The
back stroke is sometimes felt a considerable distance from the place of
the original lightning stroke.

Synonym--Return Stroke.


Back Stroke.
(a) In telegraphy the return stroke of the lever in a telegraph sounder,
striking the end of the regulating screw with a sound distinct from that
which it produces on the forward stroke as it approaches the magnet
poles. It is an important factor in receiving by ear or sound reading.

(b) See Back Shock or Stroke of Lightning.


Balance.
(a) Wheatstone's Bridge, q. v., is sometimes termed the Electric
Balance.

(b) A suspension or torsion balance is one which includes a filament or
pair of filaments to whose lower end or ends are attached a horizontal
indicator often called a needle, or a magnetic needle. (See Torsion
Balance.)

(c) See Induction Balance, Hughes'.

(d) For Thermic Balance, see Bolometer.

(e) See Balance, Ampere.


56   STANDARD ELECTRICAL DICTIONARY.


Balance, Ampere.
A class of electrical measuring instruments due to Sir William Thomson
may be grouped under this head.

The instrument is a true balance or scales such as used for weighing. It
is supported by a torsional wire support in place of knife edges. At
each end it carries a circle of wire through which the current to be
tested is passed. The torsional wire support enables the current to be
carried to these wire rings. Above and below each of these rings are two
similar rings, also connected so as to receive the current. They are so
connected that the current shall go through them in opposite senses.
When a current passes, therefore, one of these rings repels and one
attracts the balanced ring.

The extent of this action measures the intensity of the current. A
sliding weight moving along a graduated scale on the balance is used to
bring the balance beam into equilibrium when the current is passing. The
degree of displacement of this weight gives the strength of the current
in amperes.

These balances are made for different currents. Thus there is a
centi-ampere balance, deka-ampere balance and others, as well as an
ampere balance.


Balata.
A gum used as an insulating material. It is the inspissated juice of a
sapotaceous tree, the bullet tree, Mimusops globosa, of tropical
America, from the Antilles to Guiana. It is intermediate in character
between caoutchouc and gutta percha. It is superior to gutta percha in
some respects, being very slightly acted on by light.

Synonym--Chicle.


B. & S.. W. G.
Abbreviation for Brown & Sharpe Wire Gauge; the regular American Wire
Gauge. (See Wire Gauge, American.)


Barad.
An absolute or fundamental unit of pressure, equal to one dyne per
square centimeter.


Barometer.
An apparatus for measuring the pressure exerted by the atmosphere. It
consists, in the mercurial form, of a glass tube, over 31 inches long,
closed at one end, filled with mercury and inverted, with its open end
immersed in a cistern of mercury. The column falls to a height
proportional to the pressure of the atmosphere from 30 to 31 inches at
the sea level. The "standard barometer" is a height of the mercury or of
the "barometric column" of 30 inches or 760 centimeters, measured from
the surface of the mercury in the cistern.

The column of mercury is termed the barometric column. Above it in the
tube is the Torricellian vacuum.

[Transcriber's note: More accurately, 29.92 inches of mercury or 14.696
PSI.]


Bars of Commutators.
The metal segments of a commutator of a dynamo or motor. They are made
of bars of copper, brass or bronze insulated from one another. (See
Commutator.)

Synonyms--Segments, Commutator Segments, Commutator Bars.


57 STANDARD ELECTRICAL DICTIONARY.


Bath.
(a) In electro-plating the solution used for depositing metal as
contained in a vat or tank; as a silver, copper, or nickel bath used for
plating articles with silver, copper, or nickel respectively.

(b) In electro-therapeutics a bath with suitable arrangements,
electrodes and connections for treating patients with electricity. It is
termed an electric bath or electro-therapeutic bath.


Bath, Bipolar Electric.
In electro-therapeutics a bath in which the electrodes are both immersed
in the water. The patient placed between them receives part of the
discharge. The electrodes are large copper plates, termed shovel
electrodes.


Bath, Electric Shower.
An electro-medical shower bath. The patient is placed on a metallic
stove or support connected to one of the electric terminals. Water
slightly alkaline is showered upon him. The other electrode is in
connection with the water. The rain of drops and streamlets is the
conductor of the current or discharge.


Bath, Multipolar Electric.
An electro-medical bath with a number of electrodes instead of two.


Bath, Stripping.
In electro-plating a solution used for dissolving and thus removing the
plating from any object. The stripping bath is of the same general type
as the plating bath for the same metal as the one to be dissolved. The
object to be "stripped" is made the anode of a plating circuit, and as
the current acts the old plating is attacked and dissolves, leaving the
body of the article bare. It is simply the operation of plating
reversed. The same term is applied to baths acting by simple solution.
Stripping baths are described under the different metals as Silver Bath,
Stripping--Gold Bath, Stripping.


Bath, Unipolar Electric.
An electro-medical bath, in which only one electrode connects with the
water of the bath. The second electrode is supported above the bath. The
patient touches this while in the water whenever electric action is
desired.



FIG. 36. THREE WIRE MOULDING OR BATTEN.



FIG. 37. TWO WIRE MOULDING OR BATTEN.


58   STANDARD ELECTRICAL DICTIONARY.


Batten.
A strip of wood grooved longitudinally for holding wires in wiring
apartments for electric light or power. In use they are fastened to the
wall, grooves inward, or else grooves outward, with the wires lying in
the grooves and covered with the covering strip. For two wire work each
batten contains two grooves; for the three wire system it contains three
grooves.

Synonym--Moulding.


Battery.
A combination of parts or elements for the production of electrical
action. The term is principally applied to voltaic batteries, but there
are also magnetic batteries, batteries of Leyden jars, and other
combinations, described in their places, which come under this category.

[Transcriber's note: A group of similar items such as questions,
machines, parts, guns, or electric cells.]


Battery, Acetic Acid.
A battery whose active solution or excitant is acetic acid or vinegar.
This acid has been used by Pulvermacher in his medical battery, as being
a substance found in every household in the form of vinegar. It is now
but little used.


Battery, Alum.
A battery using as excitant a solution of alum. This battery has had
some application for electric clocks, but only to a limited extent.



Fig. 38. BALLOON OR FLASK BATTERY.


Battery, Aluminum.
A battery in which aluminum is the negative plate and aluminum sulphate
the excitant. It is mounted like the gravity battery. Its electro-motive
force is 0.2 volt.


59  STANDARD ELECTRICAL DICTIONARY.


Battery, Bagration.
A battery with zinc and carbon electrodes immersed in earth sprinkled
with sal ammoniac (ammonium chloride). The copper is preferably first
immersed in sal ammoniac solution and dried, until a green layer is
formed on its surface.

The battery is highly praised for its constancy by De la Rive, but may
be regarded as obsolete.


Battery, Balloon.
A form of gravity battery into whose centre a globular flask, B, is
inverted, which is filled before inversion with copper sulphate, of
which 2 lbs. are used, and water, so as to remain full. This acts as a
reservoir of copper sulphate, which it constantly supplies. The glass
jar is closed with a perforated wooden cover.


Battery, Banked.
(a) A battery arranged to feed a number of separate circuits.

(b) A battery connected in parallel or in multiple arc.


Battery, Bichromate.
A battery with amalgamated zinc and carbon plates, with an exciting
fluid composed of sulphuric acid, water, and potassium bichromate. For
formula of such solutions see Electropoion Fluid--Kookogey's
Solution--Poggendorff's Solution--TrouvÉ's Solution--Delaurier's
Solution, and others. (See Index.)


Battery, Bunsen.
A two fluid porous cell battery. The negative plate is carbon, the
positive plate, amalgamated zinc. The depolarizer is nitric acid or
electropoion fluid, q.v., in which the carbon is immersed. The last
named depolarizer or some equivalent chromic acid depolarizing mixture
is now universally used.  The excitant is a dilute solution of sulphuric
acid. Originally the carbon was made cylindrical in shape and surrounded
the porous cups, in which the zinc was placed. This disposition is now
generally reversed. The electro-motive force is 1.9 volts. The
depolarizing solution is placed in the compartment with the carbon. The
excitant surrounds the zinc.



Fig. 39. BUNSEN'S BATTERY.


60   STANDARD ELECTRICAL DICTIONARY.


Battery, Cadmium.
A battery in which cadmium is the negative plate, sulphate of cadmium
solution the excitant and depolarizer, and zinc the positive plate.
Electro-motive force, .31 volt or about one third of a Daniell cell. It
is mounted like a gravity battery.


Battery, Callan.
A modification of Grove's battery. Platinized lead is used for the
negative plate, and as a depolarizer a mixture of 4 parts concentrated
sulphuric acid, 2 parts of nitric acid, and 2 parts of a saturated
solution of potassium nitrate. (See Battery, Grove's.)


Battery, Camacho's.
A battery with carbon negative and amalgamated zinc positive electrodes.
The carbon is contained in a porous cup, packed with loose carbon.
Electropoion or other fluid of that type serves as excitant and
depolarizer, and is delivered as shown from cell to cell by syphons.



Fig. 40. CAMACHO'S BATTERY.


Battery, CarrÉ's.
A Daniell battery for whose porous cup a vessel or species of sack made
of parchment paper is substituted. The battery has been used for
electric light, and has been run for 200 successive hours, by replacing
every 24 hours part of the zinc sulphate solution by water.


61  STANDARD ELECTRICAL DICTIONARY.


Battery, Cautery.
A battery used for heating a platinum wire or other conductor used for
cauterization in electro-therapeutics. The term is descriptive, not
generic.


Battery, Chloric Acid.
A battery of the Bunsen type in which an acidulated solution of
potassium chlorate is used as depolarizer.


Battery, Chloride of Lime.
A battery in which bleaching powder is the excitant. The zinc electrode
is immersed in a strong solution of salt, the carbon in a porous vessel
is surrounded with fragments of carbon and is packed with chloride of
lime (bleaching powder). There is no action on open circuit. It has to
be hermetically sealed on account of the odor. Its electro-motive force
is--initial, 1.65 volts; regular, 1.5 volts.

Synonym--Niaudet's Battery.


Battery, Chromic Acid.
Properly a battery in which chromic acid is used as a depolarizer. It
includes the bichromate battery. (See Battery, Bichromate.)


Battery, Closed Circuit.
A battery adapted by its construction to maintain a current on a closed
circuit for a long time without sensible polarization. The term is
merely one of degree, for any battery becomes exhausted sooner or later.
As examples the Grove, Bunsen or Daniell batteries may be cited.


62   STANDARD ELECTRICAL DICTIONARY.



Fig. 41. COLUMN BATTERY.


Battery, Column.
The original Volta's pile. It consists of a series of compound circular
plates, the upper or lower half, A, copper; the other, Z, of zinc.
Between each pair of plates some flannel or cloth, u, u, is laid, which
is saturated with dilute acid. As shown in the cut, the parts are laid
up in two piles, connected at the top with a bar, c, c, and with vessels
of acidulated water, b, b, as electrodes. The great point in setting it
up is to be sure that no acid runs from one disc of flannel to the next
over the outside of the plates, as this would create a short circuit.
The plates are best compound, being made up of a zinc and a copper plate
soldered together. They may, however, be separate, and merely laid one
on the other. In such case great care must be taken to admit no acid
between them.

Volta's pile is no longer used, except occasionally. TrouvÉ's blotting
paper battery (see Battery, TrouvÉ's) is a relic of it, and the same is
to be said for Zamboni's dry pile.

It rapidly polarizes, the flannel retains but little acid, so that it is
soon spent, and it is very troublesome to set up. Great care must be
taken to have the cloth discs thoroughly saturated, and wrung out to
avoid short circuiting by squeezing out of the acid.


Battery, D'Arsonval's.
A battery of the Bunsen type, differing therefrom in the solutions. As
excitant in which the zinc electrode is immersed, the following solution
is used:

Water, 20 volumes;
Sulphuric Acid (purified by shaking with a little olive or similar oil),
1 volume;
hydrochloric acid, 1 volume.

As polarizer in which the carbon is immersed the following is used:

Nitric acid, 1 volume;
hydrochloric acid, 1 volume;
water acidulated with 1/20th sulphuric acid, 2 volumes.


Battery, de la Rue.
A battery with zinc positive and silver negative electrode; the
depolarizer is silver chloride; the excitant common salt or ammonium
chloride. The cut shows one of its forms of construction.

The right hand portion of the cut, Fig. 42, shows the zinc perforated at
C for the connection from the next silver plate. The next to it is the
negative electrode of silver around which a mass of silver chloride is
cast in cylindrical form. A is a parchment paper cylinder with two holes
near its top, through which the silver wire of the negative electrode is
threaded, as shown in B. A solution of 23 parts ammonium chloride in
1,000 parts of water is the approved excitant. Its electro-motive force
is 1.03 volts.

The jars are closed with paraffin.



Fig. 42. DE LA RUE'S BATTERY.


63   STANDARD ELECTRICAL DICTIONARY.


Battery, Dry.
(a) A form of open circuit battery in which the solutions by a mass of
zinc oxychloride, gypsum, or by a gelatinous mass such as gelatinous
silica, or glue jelly, are made practically solid. Numbers of such have
been patented, and have met with considerable success.

(b) Zamboni's dry pile, q. v., is sometimes termed a dry battery.


Battery, Element of.
A term applied sometimes to a single plate, sometimes to the pair of
plates, positive and negative, of the single couple.


Battery, Faradic.
A term applied, not very correctly however, to apparatus for producing
medical faradic currents. It may be an induction coil with battery, or a
magneto-generator worked by hand.


Battery, Ferric Chloride.
A battery of the Bunsen type, in which a solution of perchloride of iron
(ferric chloride) is used for the depolarizing agent. A little bromine
is added with advantage. The depolarizing agent recuperates on standing,
by oxidation from the oxygen of the air.


Battery, Fuller's.
A battery of the Bunsen type. The zinc plate is short and conical, and
rests in the porous jar into which some mercury is poured. An insulated
copper wire connects with the zinc. A plate of carbon is in the outer
jar. The solutions are used as in the Bunsen battery.

Synonym--Mercury Bichromate Battery.


Battery, Gas.
(a) A battery whose action depends on the oxidation of hydrogen as its
generating factor. It was invented by Grove. Plates of platinum are
immersed in cups of dilute acid, arranged as if they were plates of zinc
and carbon, in an ordinary battery. Each plate is surrounded by a glass
tube sealed at the top. The plates are filled with acid to the tops.
Through the top the connection is made. A current from another battery
is then passed through it, decomposing the water and surrounding the
upper part of one set of plates with an atmosphere of oxygen and of the
other with hydrogen. Considerable quantities of these gasses are also
occluded by the plates. On now connecting the terminals of the battery,
it gives a current in the reverse direction of that of the charging
current.

This battery, which is experimental only, is interesting as being the
first of the storage batteries.

(b) Upward's Chlorine Battery and any battery of that type (see Battery,
Upward's,) is sometimes termed a gas battery.


64   STANDARD ELECTRICAL DICTIONARY.


Battery Gauge.
A pocket or portable galvanometer for use in testing batteries and
connections.


Battery, Gravity.
A battery of the Daniell type, in which the porous cup is suppressed and
the separation of the fluids is secured by their difference in specific
gravity. A great many forms have been devised, varying only in details.
The copper plate, which is sometimes disc shaped, but in any case of
inconsiderable height, rests at the bottom of the jar. Near the top the
zinc plate, also flat or of slight depth, is supported. As exciting
liquid a strong solution of copper sulphate lies at the bottom of the
jar. This is overlaid by a solution of zinc sulphate, or sodium
sulphate, which must be of considerably less specific gravity than that
of the copper sulphate solution. In charging the jar one-tenth of a
saturated solution of zinc sulphate mixed with water is sometimes used
as the upper fluid. This may be first added so as to half fill the jar.
The strong solution of copper sulphate may then be added with a syphon
or syringe underneath the other so as to raise it up. From time to time
copper sulphate in crystals are dropped into the jar. They sink to the
bottom and maintain the copper sulphate solution in a state of
saturation.



Fig. 43. GRAVITY BATTERY OF THE TROUVÉ-CALLAUD TYPE.


If the battery is left on open circuit the liquids diffuse, and metallic
copper precipitates upon the zincs. This impairs its efficiency and
creates local action. As long as the battery is kept at work on closed
circuit work but little deposition, comparatively speaking, occurs.

From time to time, in any case, the zinc plates are removed and scraped,
so as to remove the copper which inevitably forms on their surface. Care
must be taken that the zinc sulphate solution, which is constantly
increasing in strength, does not get so strong as to become of as high
specific gravity as the copper sulphate solution. From time to time some
of the upper solution is therefore removed with a syphon or syringe and
replaced with water. An areometer is useful in running this battery.


65  STANDARD ELECTRICAL DICTIONARY.


Battery, Grenet.
A plunge battery with zinc positive and carbon negative electrodes.
Electropoion or other chromic acid or bichromate solution is used as
depolarizer and excitant. The zinc plate alone is plunged into and
withdrawn from the solution.



Fig. 44. GRENET'S BATTERY.



Fig. 45. GROVE'S BATTERY.


Battery, Grove's.
A two fluid galvanic battery. A porous cup has within it a riband of
platinum, which is the negative plate; amalgamated zinc in the outer jar
is the positive plate. Dilute sulphuric acid (10 per cent. solution) is
placed in the outer jar, and strong nitric acid (40° B.) as a
depolarizer in the porous cups. Its E. M. F. is 1.96 volts.

It is objectionable, as it gives off corrosive nitrous fumes. These are
produced by the oxidation of the nascent hydrogen by the nitric acid, by
the following reaction:

3 H + H N O3 = 2 H2 O + N O. There are other reactions, one of which
results in the formation of ammonia by the reduction of the nitric acid
radical by the hydrogen. Ammonium can be detected in the spent liquids.


66   STANDARD ELECTRICAL DICTIONARY.


Battery, Hydrochloric Acid.
A battery in which hydrochloric acid is used as the excitant. Many
attempts have been made to use this acid in batteries, but the volatile
nature of the acid causes the production of so much odor with corrosive
fumes that it has never come into use.


Battery, Lead Chloride.
A battery of the lead sulphate type in which lead chloride is the
depolarizer. It has had no extended use.


Battery, Lead Sulphate.
A battery similar to MariÉ Davy's battery or the gravity battery, but
using lead sulphate as depolarizer and excitant. Lead, copper or tin is
the material of the negative plate. Becquerel used the lead sulphate as
a solid cylindrical mass surrounding a lead rod 1/5 to 1/4 inch in
diameter. One part of common salt may be mixed with 5 parts of the lead
sulphate. The electro-motive force is about 0.5 volt. The resistance is
very high.


Battery, LeclanchÉ.
An open circuit battery with porous cup. In the outer jar is a zinc rod;
a carbon plate is placed in the porous cup. The latter is packed with a
mixture of clean powdered manganese binoxide as depolarizer, and
graphite in equal volumes. A strong solution of ammonium chloride (sal
ammoniac) is placed in the outer jar. It is only used on open circuit
work. Its electromotive force is 1.48 volts, when not polarized.

The reaction is supposed to be about the following:

2 N H4 Cl + 2 Mn O2 + Zn = Zn Cl2 + 2 N H3 + H2 0 + M2 O3

The battery rapidly weakens on open circuit, but quickly recuperates.
There is another form of this battery, termed the agglomerate battery.
(See Battery, LeclanchÉ Agglomerate.)



Fig. 46. LECLANCHÉ BATTERY.


Battery, LeclanchÉ Agglomerate.
A form of the LeclanchÉ in which the porous jar is suppressed. Cakes
made of a mixture of carbon, 52 parts; manganese binoxide, 40 parts; gum
lac, 5 parts; potassium bisulphate, 3 parts, compressed at 300
atmospheres, at a temperature of 100° C. (212° F.), are fastened by
India rubber bands or otherwise against the carbon plate. These
constitute the depolarizer. Various shapes are given the carbon and
depolarizing agglomerates.


Battery, Local.
A battery supplying a local circuit (see Circuit. Local). The current is
governed by the relay situated on the main line and operated by its
current.


Battery, Main.
The battery used in operating the main line. It is usually applied to
telegraphy. Its function is then to supply current for working relays,
which in turn actuate the local circuits.

Main and local circuits and batteries are also used in the automatic
block system of railroad signalling.


67  STANDARD ELECTRICAL DICTIONARY.


Battery, MariÉ Davy's.
A two fluid porous cup battery with carbon negative plate, zinc positive
plate, and mercury sulphate, a nearly insoluble salt, as depolarizer and
excitant. Mercurous or mercuric sulphates have been used in it. Its
electromotive force is 1.5 volts. The local action and waste, owing to
the slight solubility of the mercury compounds, is very slight. If used
on close circuit it becomes polarized. It is also subject under extreme
circumstances to reversal of polarity, zinc becoming deposited upon the
carbon, and there forming a positive electrode.

In using the cells in series the level of liquid in all must be the
same, otherwise the cell in which it is lowest will become polarized and
exhausted.

Modifications of this battery on the lines of the gravity battery have
been constructed.

Synonym--Sulphate of Mercury Battery.


Battery, Maynooth's.
A battery of the Bunsen type, with cast iron negative plate. The iron
takes the passive form and is not attacked.


Battery, Medical.
A term applied very indiscriminately to medical current generators, and
to medical induction coils, or to any source of electricity, static or
current, for medical application.


68   STANDARD ELECTRICAL DICTIONARY.


Battery, Meidinger's.
A variety of Daniell cell of the gravity type. The plates are
cylindrical. The zinc plate lies against the upper walls of the vessel.
The copper plate of smaller diameter rests on the bottom. A large tube,
with an aperture in its bottom, is supported in the centre and is
charged with copper sulphate crystals. The cup is filled with a dilute
solution of Epsom salts (magnesium sulphate) or with dilute sulphuric
acid.


Battery Mud.
A deposit of mud-like character which forms in gravity batteries and
which consists of metallic copper precipitated by the zinc. It indicates
wasteful action.


Battery, Multiple-connected.
A battery connected in parallel, all the positive plates being connected
to one electrode, and all the negative to another.


Battery, Nitric Acid.
A battery in which nitric acid is used as the excitant. Owing to its
cost and volatility this acid has been but little used in batteries,
other than as a depolarizer. In Grove's battery (see Battery, Grove's)
it has been thus used.


Battery of Dynamos.
A number of dynamos may be arranged to supply the same circuit. They are
then sometimes termed as above, a Dynamo Battery. They may be arranged
in series or in parallel or otherwise combined.


Battery of Leyden Jars.
To produce the quantity effect of a single large Leyden jar with a
number of small ones they are often connected in parallel and termed a
battery. In such case the inner coatings are all connected by regular
bar conductors, and the outside coatings are also all in connection.
They are conveniently placed in a box or deep tray whose inner surface
is lined with tinfoil, with an outside connection for grounding, etc.
The cascade, q. v., arrangement is not so generally termed a battery.


Battery, Open Circuit.
A battery adapted for use in open circuit work. Its main requirement is
that it shall not run down, or exhaust itself when left on open circuit.
The LeclanchÉ battery is very extensively used for this work. Its action
is typical of that of most open circuit batteries. It is without any
action on open circuit. It is very quickly exhausted on closed circuit,
but recuper

C.
(a) Abbreviation for Centigrade, as 100 C., meaning 100 Centigrade. (See
Centigrade Scale.)

(b) A symbol of current or of current strength. Thus in the expression
of Ohm's law C = E/R. C indicates current strength or intensity, not in
any fixed unit, but only in a unit of the same order in which E and R
are expressed; E Indicating electro-motive force and R resistance.


Cable.
(a) Abbreviation for Cablegram, q. v.

(b) v. It is also used as a verb, meaning to transmit a message by
submarine cable.

(c). An insulated electric conductor, of large diameter. It often is
protected by armor or metallic sheathing and may be designed for use as
an aerial, submarine, subterranean or conduit cable. A cable often
contains a large number of separately insulated conductors, so as to
supply a large number of circuits.


Cable, Aerial.
A cable usually containing a large number of separately insulated wires,
and itself insulated. It is suspended in the air. As its weight is
sometimes so great that it could not well sustain it, a suspending wire
is in such cases carried along with it, to which it is suspended by
cable hangers, q. v.


Cable Box.
A box for receiving underground cable ends and connecting the separate
wires of the cable to air-line wires. It is often mounted on a pole,
which forms the starting point of the air-line portion of the system.


Cable, Bunched.
A cable containing a number of separate and individual conductors. In
some forms it consists virtually of two or more small cables laid
tangent to each other and there secured. Thus each in section represents
two or more tangent circles with the interstice solidly filled with the
metal sheathing.


Cable, Capacity of.
The electrostatic capacity of a cable. A cable represents a Leyden jar
or static condenser. The outer sheathing or armor, or even the more or
less moist coating, if it is unarmored, represents one coating. The wire
conductors represent the other coating, and the insulator is the
dielectric.

The capacity of a cable interferes with its efficiency as a conductor of
broken or interrupted currents, such as are used in telegraphy or
telephoning. As each impulse or momentary current is sent into the line,
it has to charge the cable to at least a certain extent before the
effects of the current are perceptible at the other end. Then the cable
has to discharge itself. All this creates a drag or retardation.

The capacity of a cable is used to determine the locality of breaks in
the continuity of the conductors. The capacity per unit of length being
accurately known, it is obvious that, if the conductor breaks without
disturbance of the insulator, the distance of the break from the end can
be ascertained by determining the capacity of the cable from one end.
This capacity will be in proportion to the capacity of a mile, a knot or
any fixed unit, as the distance to the break is to the length used as
standard.


96   STANDARD ELECTRICAL DICTIONARY.


Cable Core.
The conductors of a cable. They are generally copper wire. In a
telephone cable they may be very numerous and insulated from each other.
In ocean cables they may be a group of bare wires twisted or laid
together. Sometimes the conductors are arranged for metallic circuits,
each pair being distinguished by special colored windings.


Cable, Duplex.
A cable containing two wires, each with separate insulation, so as to be
virtually two cables, laid and secured parallel and side by side.


Cable, Flat.
A cable, flat in shape, so as to lie closely against a wall or ceiling.


Cablegram.
A message which has been transmitted or is to be transmitted by a
submarine cable. It is sometimes called a cable.


Cable Grip.
A grip for holding the end of a cable, when the cable is to be drawn
into a conduit in a subway. It is an attachment to provide the cable
with an eye or loop. Its end is a split socket and embraces the end of
the cable, and is secured thereto by bolts driven through the cable end.
In drawing a cable into a conduit a capstan and rope are often used, and
the rope is secured to the cable end by the grip.



Fig. 73. CABLE HANGER, CABLE, AND SUSPENDING WIRE.



Fig. 74. CABLE HANGER, OPEN.


Cable Hanger.
When a heavy electric cable is suspended from poles it often would be
unsafe to trust to its longitudinal strength to support or sustain its
own weight unless the poles were very near together. In such case an
auxiliary or sustaining wire is run along with it, and by clips or
hangers the cable is connected thereto at as frequent intervals as seem
desirable. The contrivance may take the form of a strip of metal
surrounding the cable and carrying a hook or eye through which the
supporting wire passes.

Synonym--Cable Clip.


97  STANDARD ELECTRICAL DICTIONARY


Cable Hanger Tongs.
Tongs for attaching cable hangers, q.v. They have long handles so as to
be worked from the ground at the middle of a span.


Cable, Suspending Wire of.
A wire by which an aerial cable is in part or entirely suspended. The
cable, being incapable of sustaining its own weight, is secured by clips
or hangers to a wire, strong from pole to pole immediately above it.
(See Cable Hanger.)


Cable Tank.
A tank in which a submarine cable is coiled away on board a cable-laying
ship, or in the factory on shore for the purpose of testing or
watching its insulation. Sometimes, in order to test it under pressures
approximating to those it will be subjected to in practice, the tank is
closed and the portion of cable within it is subjected to hydraulic
pressure. This represents the pressure it will be exposed to in deep
water.


Calamine.
A mineral; zinc silicate; formula Zn2 Si 03, crystalline system,
Orthorhombic; specific gravity, 3.16-3.9.

The crystals often show strong pyroelectric properties.


Calibration.
The determination by experiment or calculation of the value of the
readings of an instrument, such as a galvanometer or eudiometer. Thus if
a tangent galvanometer has its circle graduated in degrees, a table of
the value of tangents corresponding to every reading occurring in
practice would represent a calibration by calculation. A determination
of the current required to produce each deflection would be a
calibration in the more usual sense. Calibration is generally absolute,
as referring to some fixed unit, but it may be relative, as between two
things both of unknown absolute value.


Calibration, Absolute.
The determination of the absolute value of currents producing given
deflections in a galvanometer, or in other instruments the determination
of corresponding values, as the instrument may be a magnetometer,
quadrant electrometer, or other apparatus.


Calibration, Invariable.
Calibration applicable to specially constructed galvanometers, which is
unaffected by the proximity of masses of iron or field magnets. Such
galvanometers must have a constant controlling field. Such is given by a
powerful permanent magnet, whose field is practically unaffected by the
causes named. Or else, in place of a controlling field, a spring maybe
used to which the needle is attached, and which tends to hold it in one
position.


98   STANDARD ELECTRICAL DICTIONARY.


Calibration, Relative.
The determination of the law connecting the various indications of an
instrument, such as the deflections of the needle of a galvanometer,
with the relative causes; in the case of a galvanometer, the strength of
the currents or the electro-motive forces producing them directly or
indirectly.


Call Bell.
A bell rung by pressing a button or otherwise to call the attention of a
person in a distant place. They can be classified into a great variety
of types according to their uses or construction.


Call Button.
A push button used for ringing a call bell, sounding a buzzer, working
an annunciator and for similar purposes. (See Push Button.)

Synonym--Push Button.


Calling Drop.
In a telephone exchange or telegraph office a drop shutter annunciator,
which falls to call the attention of the operator, notifying him that
the line connected to such drop is to be connected to some other
circuit.


Calorie or Calory.
A practical unit of heat. There are two calories, respectively called
the great and the small calorie, or the kilogram and the gram calorie.
The first is the quantity of heat required to raise the temperature of
one kilogram of water one degree centigrade. The second is the quantity
of heat required to raise the temperature of one gram of water one
degree centigrade.


Calorimeter.
An apparatus for measuring the quantity of heat evolved or produced by
or under different conditions. Dulong's water calorimeter consists of a
water jacket, and by the increase of temperature of the water and
enclosing vessels the amount of heat produced by anything in the inner
vessels is determined. The amount of ice a heated body will melt is
sometimes made the basis of a calorimeter. The expansion of a fluid, as
water, may be used. In the calorimeter shown in the cut the heat
produced in a conductor by the passage of an electric current is caused
to heat water whose temperature is shown by a thermometer immersed
therein. The increase of temperature and the weight of the water give
the basis for a determination of the heat produced by the current.
Knowing the resistance of the conductor immersed, the watts can be
calculated. This gives the bases for the determination of the
heat-equivalent of electric energy. This is but an imperfect
calorimeter, as it constantly would lose heat by the surrounding
atmosphere, and would cease to operate as a calorimeter when the water
was as hot as the wire normally would be, for then it would not absorb
all the heat.



Fig. 75. CALORIMETER.


99 STANDARD ELECTRICAL DICTIONARY.


Candle.
The generally accepted unit of illuminating power; there are
three kinds in use as standards. (See Candle, Decimal--Candle, German
Standard--Candle, Standard.)


Candle, Concentric.
An electric candle of the Jablochkoff type, having a small solid carbon
inside of an outside tubular carbon, the space between being filled with
refractory material corresponding to the colombin, q. v., of the
ordinary type. The arc springs across from one carbon to the other.


Candle, Debrun.
An arc lamp with approximately parallel carbons. A transverse priming
connects their bases, and the arc starting there at once flies out to
the end.


Candle, Decimal.
A standard of illuminating power, proposed to the Congress of
Electricians of 1889 by Picou. It is one-twentieth of a Viole, or almost
exactly one standard candle. (See Viole's Standard of Illuminating
Power.)

Candle, Electric.
An arc lamp regulated by simple gravity, or without any feed of the
carbons or special feeding apparatus, generally for the production of an
arc light of low intensity. This definition may be considered too
elastic, and the word may be restricted to parallel carbon lamps in
which the arc springs across from carbon to carbon. For the latter class
an alternating current is used to keep the carbons of equal length. They
are but little used now. Various kinds have been invented, some of which
are given here.


Candle, German Standard.
A standard of illuminating power used in Germany. It is a paraffin
candle, 6 to the pound, 20 millimeters diameter; flame, 56 millimeters
high; rate of consumption, 7.7 grams per hour. Its value is about two
per cent. lower than the English standard candle.


100   STANDARD ELECTRICAL DICTIONARY.


Candle Holder.
A clamp for holding electric candles of the Jablochkoff type. The ones
shown in the cut designed for Jablochkoff  candles comprise a pair of
metallic clamps, each member insulated from the other, and connected as
terminals of the circuit. When the candle is placed in position the
metal pieces press against the carbons of the candle and thus convey the
current. Below each member of the clamps is a binding screw for the line
wire terminals.



Fig. 76. JABLOCHKOFF CANDLE HOLDERS.



Fig. 77. JABLOCHKOFF CANDLE.


Candle, Jablochkoff.
An arc lamp without regulating mechanism, producing an arc between the
ends of parallel carbons. It consists of two parallel rods of carbon,
between which is an insulating layer of non-combustible material called
the colombin. Kaolin was originally employed for this part; later, as
the fusion of this material was found to short- circuit the arc, a
mixture of two parts of calcium sulphate and one of barium sulphate was
used. The carbons are 4 millimeters (.16 inch) thick, and the colombin
is 3 millimeters (.12 inch) wide and two-thirds as thick. A little slip
of carbon is placed across the top, touching both carbons to start the
arc. Once started the candle burns to the end, and cannot be restarted
after ignition, except by placing a short conductor across the ends, as
at first. The Jablochkoff candle may now be considered as virtually
extinct in this country. In France at one time a great number were in
use.

To keep the carbons of equal length an alternating current must always
be used with them. Special alternating combinations were employed in
some cases where a direct current had to be drawn upon.


Candle, Jamin.
An arc lamp with approximately parallel carbons, one of which oscillates
and is controlled by an electro-magnet and armature. A coil of wire is
carried around the carbons to keep the arc steady and in place. The
frame and wire coils have been found unsatisfactory, as causing a
shadow.


Candle Power.
The amount of light given by the standard candle. The legal English and
standard American candle is a sperm candle burning two grains a minute.
It should have burned some ten minutes before use, and the wick should
be bent over and have a red tip. Otherwise its readings or indications
are useless. A sixteen candle power lamp means a lamp giving the light
of sixteen candles. The candle power is a universal unit of illuminating
power.


101  STANDARD ELECTRICAL DICTIONARY.


Candle Power, Rated.
The candle power of arc lamps is always stated in excess of the truth,
and this may be termed as above. A 2000 candle power lamp really gives
about 800 candles illumination.

Synonym--Nominal Candle Power.


Candle Power, Spherical.
The average candle power of a source of light in all directions. An arc
lamp and an incandescent lamp vary greatly in the intensity of light
emitted by them in different directions. The average of a number of
determinations at various angles, the lamp being moved about into
different positions, is taken for the spherical candle power.


Candle, Standard.
A standard of illuminating power. Unless otherwise expressed the English
standard sperm candle is indicated by this term. (See Candle Power.)


Candle, Wilde.
An arc lamp with approximately parallel carbons. One of the carbons can
rotate through a small arc being pivoted at its base. This oscillation
is regulated by an electro-magnet at its base, and the carbons touch
when no current is passing. They separate a little when the current
passes, establishing an arc. The regulation is comparable to that of a
regular arc lamp.



Fig. 78. WILDE CANDLE.


Caoutchouc.
India rubber; a substance existing in an emulsion or solution in the
juice of certain trees and vines of the tropics, whence it is obtained
by coagulation and drying. The name "rubber" is due to the fact that one
of its earliest uses was for erasing pencil marks by rubbing. It has a
very high value as an insulator. The unworked crude rubber is called
virgin gum; after working over by kneading, it is termed masticated or
pure gum rubber; after mixture with sulphur and heating, it is termed
vulcanized rubber. If enough sulphur is added it becomes hard, and if
black, is termed ebonite; if vermilion or other pigment is also added to
produce a reddish color, it is termed vulcanite. The masticated gum
dissolves more or less completely in naphtha (sp. gr., .850) benzole,
turpentine, chloroform, ether and other similar liquids.. The resistance
per centimeter cube of "Hooper's" vulcanized India rubber, such as is
used in submarine cables is 1.5E16 ohms. The specific inductive capacity
of pure India rubber is 2.34--of vulcanized 2.94 (Schiller).

Synonyms--India Rubber--Rubber.


102   STANDARD ELECTRICAL DICTIONARY.


Capacity, Dielectric.
The capacity of a dielectric in retaining an electrostatic charge; the
same as Specific Inductive Capacity. 'The number expressing it is
sometimes called the dielectric constant. (See Capacity, Specific
Inductive.)


Capacity, Electric, or Electrostatic.
The relative capacity of a conductor or system to retain a charge of
electricity with the production of a given difference of potential. The
greater the charge for a given change of potential, or the less the
change of potential for a given charge the greater the capacity. The
measure of its capacity is the amount of electricity required to raise
the potential to a stated amount. The unit of capacity is the farad, q.
v. Electric capacity is comparable to the capacity of a bottle for air.
A given amount of air will raise the pressure more or less, and the
amount required to raise its pressure a stated amount might be taken as
the measure of capacity, and would be strictly comparable to
electrostatic charge and potential change. The capacity, K, is obviously
proportional to the quantity, Q, of the charge at a given potential, E,
and inversely proportional to the potential, E, for a given quantity, Q,
or,
  (1) K == Q/E
  and
  (2) Q = K * E,
or, the quantity required to raise a conductor by a given potential is
equal to the capacity of the conductor or system multiplied by the rise
of potential. The capacity of a conductor depends upon its environments,
such as the nature of the dielectric surrounding it, the proximity of
oppositely charged bodies and other similar factors. (See
Dielectric-Condenser-Leyden jar.)

The dimensions of capacity are found by dividing a quantity of
electricity by the potential produced in the conductor by such
quantity.

Quantity ( ((M^.5)*(L^1.5)) / T ) / potential ( ((M^.5)*(L^.5)) / T ) = L.


Capacity, Instantaneous.
The capacity of a condenser when connected only for an instant to a
source of electricity. This is in contrast to electric absorption (see
Absorption, Electric), and is capacity without such absorption taking
part in the action.


103  STANDARD ELECTRICAL DICTIONARY.


Capacity of a Telegraph Conductor.
The electric capacity of a telegraphic conductor is identical in quality
with that of any other conductor. It varies in quantity, not only for
different wires, but for the same wire under different environments, as
the wire reacting through the surrounding air or other dielectric upon
the earth, represents one element of a condenser, the earth, in general,
representing the other. Hence, a wire placed near the earth has greater
capacity than one strung upon high poles, although the wires may be
identical in length, material and diameter. The effect of high capacity
is to retard the transmission of intermitting signals. Thus, when--as in
the Morse system--a key is depressed, closing a long telegraph current
and sending a signal into a line, it is at least very probable that a
portion of the electricity travels to the end of the wire with the
velocity of light. But as the wire has to be charged, enough current to
move the relay may not reach the end for some seconds.


Capacity of Polarization of a Voltaic Cell.
The relative resistance to polarization of a voltaic cell, measured by
the quantity of electricity it can supply before polarization. A
counter-electromotive force may be developed, or the acid or other
solution may become exhausted. The quantity of electricity delivered
before this happens depends on the size and type of cell and other
factors.


Capacity, Residual.
When two insulated conductors are separated by a dielectric, and are
discharged disruptively by being connected or nearly connected
electrically, on removing the discharger it is found that a slight
charge is present after a short interval. This is the residual charge.
(See Charge, Residual.) Shaking or jarring the dielectric facilitates
the complete discharge. This retaining of a charge is a phenomenon of
the dielectric, and as such, is termed residual capacity. It varies
greatly in different substances. In quartz it is one-ninth what it is in
air. Iceland spar (crystalline calcite) seems to have no residual
capacity. The action of shaking and jarring in facilitating a discharge
indicates a mechanical stress into which the electrostatic polarization
of the conductor has thrown the intervening dielectric.


Capacity, Specific Inductive.
The ratio of the capacity of a condenser when its plates are separated
by any substance to the capacity of the same condenser when its plates
are separated by air.

A static accumulator consists of two conducting surfaces separated by an
insulator. It is found that the capacity of an accumulator for an
electric charge, which varies with or may be rated by the potential
difference to which its conductors will be brought by the given charge,
varies with the nature of the interposed dielectric, and is proportional
to a constant special to each substance. This constant is the specific
inductive capacity of the dielectric.

The same condenser will have a higher capacity as the dielectric is
thinner, other things being equal. But different dielectrics having
different specific inductive capacities, the constant may be determined
by ascertaining the relative thicknesses of layers having the same total
inductive capacity. The thicker the layer, the higher is its specific
inductive capacity.

Thus it is found that 3.2 units thickness of sulphur have the same total
inductive capacity as 1 unit thickness of air. In other words, if
sulphur is interposed between two conducting plates, they may be
separated to over three times the distance that would be requisite to
retain the same capacity in air. Hence, sulphur is the better
dielectric, and air being taken as unity, the specific inductive
capacity of sulphur is 3.2.


104   STANDARD ELECTRICAL DICTIONARY.


The specific inductive capacity of a dielectric varies with the time and
temperature. That of glass rises 2.5 per cent. between 12° C. (53.6° F.)
and 83° C. (181.4° F.). If a condenser is discharged disruptively, it
retains a small residual charge which it can part with later. If a
metallic connection is made between the plates, the discharge is not
instantaneous. Vibration shaking and jarring facilitate the complete
discharge. All this shows that the charge is a phase of the dielectric
itself, and indicates a strained state into which it is brought.

The following table gives the specific inductive capacity of various
substances:

                         Specific Inductive Capacity.
Substance                                         Specific
                                                  Inductive   Authority
                                                  Capacity.
Vacuum, air at about 0.001 millimeters pressure   0.94 about  Ayrton
Vacuum, air at about 5 millimeters                0.9985      Ayrton
                                                  0.99941     Boltzmann
Hydrogen at about 760 millimeters pressure        0.9997      Boltzmann
                                                  0.9998      Ayrton
Air at about 760 millimeters pressure             1.0         Taken as the
                                                              standard
Carbon Dioxide at about 760 millimeters pressure  1.000356    Boltzmann
                                                  1.0008      Ayrton
Olefiant Gas at about 760 millimeters pressure    1.000722    Boltzmann
Sulphur Dioxide at about 760 millimeters pressure 1.0037      Ayrton
Paraffin Wax, Clear                               1.92        Schiller
                                                  1.96        WÜllner
                                                  1.977   Gibson and Barclay
                                                  2.32        Boltzmann
Paraffin Wax, Milky                               2.47        Schiller
India Rubber, Pure                                2.34        Schiller
India Rubber, Vulcanized                          2.94        Schiller
Resin                                             2.55        Boltzmann
Ebonite                                           2.56        WÜllner
                                                  2.76        Schiller
                                                  3.15        Boltzmann
Sulphur                                           2.88 to 3.21  WÜllner
                                                  3.84        Boltzmann
Shellac                                           2.95 to 3.73  WÜllner
Gutta percha                                      4.2
Mica                                              5
Flint Glass, Very light                           6.57        J. Hopkinson
Flint Glass, Light                                6.85        J. Hopkinson
Flint Glass, Dense                                7.4         J. Hopkinson
Flint Glass, Double extra dense                  10.1         J. Hopkinson


105  STANDARD ELECTRICAL DICTIONARY.


Capacity, Unit of.
The unit of capacity is the capacity of a surface which a unit quantity
will raise to a unit potential. The practical unit is the surface which
a coulomb will raise to one volt, and is called the farad, q. v.


Capacity, Storage.
In secondary batteries the quantity of electrical current which they can
supply when charged, without undue exhaustion. It is expressed in
ampere-hours. The potential varies so little during the discharge that
it is assumed to be constant.


Capillarity.
The reaction between liquid surfaces of different kinds or between
liquid an

straining between the surface of the charged body, and some
complimentary charged surface or surfaces, near or far, of large or
small area, of even or uneven distribution.


Charge. v.
(a) To introduce an electrostatic charge, as to charge a condenser.

(b) To decompose the elements of a secondary battery, q. v., so as to
render it capable of producing a current. Thus, a spent battery is
charged or recharged to enable it to do more work.

Synonyms--Renovate--Revivify--Recharge.


115  STANDARD ELECTRICAL DICTIONARY.


Charge, Bound.
A charge of electricity borne by the surface of a body so situated with
reference to another oppositely charged body, that the charge is
imperceptible to ordinary test, will not affect an electroscope nor
leave the surface if the latter is connected to the earth. To discharge
such a body it must be connected to its complimentarily charged body.
The bound charge was formerly called dissimulated or latent electricity.
(See Charge, Free.)

The charge or portion of a charge of a surface which is neutralized
inductively by a neighboring charge of opposite kind. The degree of
neutralization or of binding will depend on the distance of the two
charged surfaces from one another and on the electro-static nature of
the medium intervening, which must of necessity be a dielectric. A
charge not so held or neutralized is termed a free charge. Thus a
surface may be charged and by the approach of a surface less highly
charged may have part of its charge bound. Then if connected to earth.
it will part with its unbound or free charge, but will retain the other
until the binding surface is removed, or until the electricity of such
surface is itself bound, or discharged, or until connection is made
between the two surfaces. Thus a body may have both a bound and a free
charge at the same time.


Charge, Density of.
The relative quantity of electricity upon a given surface. Thus a
charged surface may have an evenly distributed charge or one of even
density, or an unevenly distributed charge or one of uneven density. In
a thunderstorm the earth has a denser charge under the clouds than
elsewhere.

Synonym--Electrical Density.


Charge, Dissipation of.
As every body known conducts electricity, it is impossible so to
insulate a surface that it will not lose its charge by leakage. An
absolute vacuum might answer, and Crookes in a high vacuum has retained
a charge against dissipation for years. The gradual loss is termed as
above.


Charge, Distribution of.
The relation of densities of charge on different parts of a charged
body. On a spherical conductor the charge is normally of even
distribution; on other conductors it is unevenly distributed, being of
greatest density at points, edges, and parts of smallest radius of
curvature. Even distribution can also be disturbed by local induction,
due to the presence of oppositely charged bodies.


116   STANDARD ELECTRICAL DICTIONARY.


Charge, Free.
The charge borne by an insulated body, independent of surrounding
objects. Theoretically it is an impossibility. A charge always has its
compliment somewhere in surrounding objects. As a matter of convenience
and convention, where the complimentary charge is so distributed that
its influence is not perceptible the charge is called a free charge. If
connected to earth the free charge will leave the body. If the body is
connected with an electroscope the free charge will affect the same.
(See Charge, Bound.)


Charge, Residual.
When a Leyden jar or other condenser is discharged by the ordinary
method, after a few minutes standing a second discharge of less amount
can be obtained from it. This is due to what is known as the residual
charge. It seems to be connected in some way with the mechanical or
molecular distortion of the dielectric. The jarring of the dielectric
after discharge favors the rapidity of the action, diminishing the time
required for the appearance of the residual charge. The phenomenon, it
will be seen, is analogous to residual magnetism. This charge is the
reciprocal of electric absorption and depends for its amount upon the
nature of the dielectric. (See Absorption, Electric, and Capacity,
Residual.)

Synonym--Electric Residue.


Chatterton's Compound.
A cement used for cementing together layers or sheets of gutta percha,
and for similar purposes in splicing telegraph cables. Its formula is:
  Stockholm Tar,   1 part.
  Resin,           1 part.
  Gutta Percha,    3 parts.
All parts by weight.


Chemical Change.
When bodies unite in the ratio of their chemical equivalents, so as to
represent the satisfying of affinity or the setting free of thermal or
other energy, which uniting is generally accompanied by sensible heat
and often by light, as in the ignition of a match, burning of a candle,
and, when the new compound exhibits new properties distinct from those
of its components, a chemical combination is indicated. More definitely
it is a change of relation of the atoms. Another form of chemical change
is decomposition, the reverse of combination, and requiring or absorbing
energy and producing several bodies of properties distinct from those of
the original compound. Thus in a voltaic battery chemical combination
and decomposition take place, with evolution of electric instead of
thermal energy.


Chemical Equivalent.
The quotient obtained by dividing the atomic weight, q. v., of an
element by its valency, q. v. Thus the atomic weight of oxygen is 16,
its valency is 2. its chemical equivalent is 8. It is the weight of the
element corresponding to a unit weight of hydrogen, either as replacing
it, or combining with it. In electro-chemical calculations the chemical
equivalent is often conveniently used to avoid the necessity of dividing
by the valency when atomic weights are used. The latter is really the
better practice. The atomic weights in the old system of chemical
nomenclature were chemical equivalents.


117  STANDARD ELECTRICAL DICTIONARY.


Chemical Recorder.
A form of telegraphic recorder in which the characters, often of the
Morse alphabet or some similar one, are inscribed on chemically prepared
paper by decomposition affecting the compound with which the paper is
charged. In the original chemical recorder of Bain, the instrument was
somewhat similar to the Morse recorder, except that the motionless
stylus, S, always pressing against the paper was incapable of making any
mark, but being of iron, and the paper strip being impregnated with
potassium ferrocyanide, on the passage of a current a stain of Prussian
blue was produced where the stylus touched the paper. The current passes
from the line by way of the iron stylus, through the paper, and by way
of a brass surface, M, against which the paper is held and is pressed by
the stylus, to the earth. This recorder is extremely simple and has no
part to be moved by the current. The solution in which the paper is
dipped contains a mixture of potassium ferrocyanide and ammonium
nitrate. The object of the latter is to keep the paper moist. In recent
recorders a solution of potassium iodide has been used, which gives a
brown stain of free iodine, when the current passes. This stain
disappears in a few days.



Fig. 83. BAIN'S TELEGRAPH EMPLOYING CHEMICAL RECORDER.


In the cut, R is the roll of paper, B is a tank of solution with roll,
W1, for moistening the paper; M is the brass surface against which the
stylus, S, presses the paper, P P; W, W are feed rollers; T is the
transmitting key, and zk the battery; Pl, Pl are earth plates. The
apparatus is shown duplicated for each end.


118   STANDARD ELECTRICAL DICTIONARY.


Chemistry.
The science treating of atomic and molecular relations of the elements
and of chemical compounds of the same.


Chimes, Electric.
An apparatus employed to illustrate the principles of the electrostatic
charge, involving the ringing of bells by electrostatic attraction and
repulsion. It is used in connection with a frictional, or influence
electric machine. Two bells are employed with a button or clapper
suspended between them. One bell is connected to one of the prime
conductors, q. v., of the machine. The other insulated therefrom is
connected to earth, or if an influence machine is used, to the other
prime conductor. The clappers are hung by a silk thread, so as to be
entirely insulated. On working the machine the bells become oppositely
excited. A clapper is attracted to one, then when charged is repelled
and attracted to the other, it gives up its charge and becoming charged
with similar electricity to that of the bell it touches, is repelled and
attracted to the other, and this action is kept up as long as the
excitement continues, the bells ringing continuously.



Fig. 84. ELECTRIC CHIMES.


Chronograph, Electric.
An apparatus for indicating electrically, and thereby measuring, the
lapse of time. The periods measured may be exceedingly short, such as
the time a photographic shutter takes to close, the time required by a
projectile to go a certain distance, and similar periods.

A drum rotated with even and known velocity may be marked by a stylus
pressed upon it by the action of an electro-magnet when a key is
touched, or other disturbance. Then the space between two marks would
give the period elapsing between the two disturbances of the circuit. As
it is practically impossible to secure even rotation of a drum, it is
necessary to constantly measure its rate of rotation. This is effected
by causing a tuning-fork of known rate of vibration to be maintained in
vibration electrically. A fine point or bristle attached to one of its
arms, marks a sinuous line upon the smoked surface of the cylinder. This
gives the basis for most accurately determining the smallest intervals.
Each wave drawn by the fork corresponds to a known fraction of a second.

For projectiles, the cutting of a wire opens a circuit, and the opening
is recorded instead of the closing. By firing so as to cut two wires at
a known distance apart the rate is obtained by the chronograph.

Synonym--Chronoscope.


119  STANDARD ELECTRICAL DICTIONARY.


Chutaux's Solution.
A solution for bichromate batteries. It is composed as follows:
  Water,                1,500 parts
  Potassium bichromate,   100 parts
  mercury bisulphate,     100 parts
  66° sulphuric acid,      50 parts.

Circle, Galvanic or Voltaic.
A term for the voltaic circuit; obsolete.



Fig. 85. MAGIC CIRCLE.


Circle, Magic.
A form of electro-magnet. It is a thick circle of round iron and is used
in connection with a magnetizing coil, as shown, to illustrate
electro-magnetic attraction.


120   STANDARD ELECTRICAL DICTIONARY.


Circuit.
A conducting path for electric currents properly forming a complete path
with ends joined and including generally a generating device of some
kind. Part of the conduction may be true and part electrolytic. (See
Electrolytic Conduction.) The term has become extended, so that the term
is often applied to any portion of a circuit conveniently considered by
itself. The simplest example of a complete circuit would be a circular
conductor. If rotated in the earth's field so as to cut its lines of
force a current would go through it, and it would be an electric
circuit. Another example is a galvanic battery with its ends connected
by a wire. Here the battery generates the current which, by electrolytic
conduction, goes through the battery and by true conduction through the
wire. For an example of a portion of a circuit spoken of as "a circuit"
see Circuit, Astatic.


Circuit, Astatic.
A circuit so wound with reference to the direction of the currents
passing through it that the terrestrial or other lines of force have no
directive effect upon it, one member counteracting the other. It may be
produced by making the wire lie in two closed curves, A and B, each
enclosing an equal area, one of identical shape and disposition with the
other, and with the current circulating in opposite directions in each
one. Thus each circuit represents a magnetizing turn of opposite
polarity and counteracting each other's directive tendency exhibited in
a field of force with reference to an axis a c. Another form of astatic
circuit is shown in Fig. 86. The portions C, D, lying on opposite sides
of the axis of rotation a c, are oppositely acted on by the earth's
directive force as regards the direction of their rotation.



Figs. 86 and 87. ASTATIC CIRCUITS.


Circuit, Branch.
A circuit dividing into two or more parts in parallel with each other.


121  STANDARD ELECTRICAL DICTIONARY.


Circuit Breaker.
Any apparatus for opening and closing a circuit is thus termed, but it
is generally applied to automatic apparatus. A typical circuit breaker
is the hammer and anvil of the induction coil. (See Induction Coil;
Anvil.) Again a pendulum connected to one terminal of a circuit may
swing so as to carry a point on its lower end through a globule of
mercury as it swings, which globule is connected to the other terminal.
A great many arrangements of this character have been devised.

Synonym.--Contact Breaker.


Circuit Breaker, Automatic.
A circuit breaker worked by the apparatus to which it is attached, or
otherwise automatically. (See Induction Coil; Anvil; Bell, Electric.)


Circuit Breaker, File.
A coarsely cut file, forms one terminal of an electric circuit, with a
straight piece of copper or steel for the other terminal. The latter
terminal drawn along the teeth makes and breaks the contact once for
every tooth. The movable piece should have an insulated handle.


Circuit Breaker, Mercury.
A circuit breaker which may be identical in principle, with the
automatic circuit breaker of an induction coil, but in which in place of
the anvil, q. v., a mercury cup is used, into which the end of a wire
dips and emerges as it is actuated by the impulses of the current. Each
dip makes the contact, which is broken as the wire springs back. The
mercury should be covered with alcohol to protect it from oxidation.


Circuit Breaker, Pendulum.
A circuit breaker in which a pendulum in its swing makes and breaks a
contact. It may be kept in motion by clockwork, or by an electro-magnet,
attracting intermittently an armature attached to its rod, the
magnet circuit being opened and closed by the pendulum or circuit
breaker itself. A mercury contact may be used with it.



Fig. 88. PENDULUM CIRCUIT BREAKER.


122   STANDARD ELECTRICAL DICTIONARY.


Circuit Breaker, Tuning Fork.
A circuit breaker in which a tuning fork makes and breaks the circuit.
Each vibration of one of the prongs in one direction makes a contact,
and the reverse vibration breaks a contact. The adjustment is
necessarily delicate, owing to the limited amplitude of the motion of
the fork. The fork is kept in vibration sometimes by an electro-magnet,
which is excited as the circuit is closed by the fork. One leg of the
fork acts as the armature of the magnet, and is attracted according to
its own natural period.


Circuit Breaker, Wheel.
A toothed wheel with a spring bearing against its teeth. One terminal of
a circuit connects with the wheel through its axle, the other connects
with the spring. When the wheel is turned the circuit is opened and
closed once for each tooth. The interstices between teeth on such a
wheel may be filled with insulating material, giving a cylindrical
surface for the contact spring to rub on.



Fig. 89--TOOTHED WHEEL CIRCUIT BREAKER.


Circuit, Closed.
A circuit whose electric continuity is complete; to make an open circuit
complete by closing a switch or otherwise is to close, complete, or make
a circuit.

Synonyms--Completed Circuit--Made Circuit.


Circuit, Compound.
A circuit characterized by compounding of generating or receiving
devices, as including several separate batteries, or several motors, or
other receiving devices. It is sometimes used to indicate a circuit
having its battery arranged in series. It should be restricted to the
first definition.


123  STANDARD ELECTRICAL DICTIONARY.


Circuit, Derived.
A partial circuit connected to two points of another circuit, so as to
be in parallel with the portion thereof between such two points; a shunt
circuit.

Synonyms--Shunt Circuit--Derivative Circuit--Parallel Circuit.


Circuit, Electric, Active.
A circuit through which a current passes. The circuit itself need only
be a conducting ring, or endless wire. Generally it includes, as part of
the circuit, a generator of electro-motive force, and through which
generator by conduction, ordinary or electrolytic, the same current goes
that passes through the rest of the circuit. One and the same current
passes through all parts of a series circuit when such current is
constant.

A current being produced by electro-motive force, and electromotive
force disappearing in its production in an active circuit, there must be
some source of energy which will maintain electromotive force against
the drain made upon it by the current.

The simplest conception of an active electric circuit is a ring or
endless conductor swept through a field of force so as to cut lines of
force. A simple ring dropped over a magnet pole represents the
simplification of this process. In such a ring a current, exceedingly
slight, of course, will be produced. In this case there is no generator
in the circuit. An earth coil (see Coil, Earth,) represents such a
circuit, with the addition, when experimented with, of a galvanometer in
the circuit.

In practice, a circuit includes a generator such as a battery or dynamo,
and by conductors is led through a continuous path. Electric lamps,
electrolytic cells, motors and the like may be included in it.

The term "circuit" is also applied to portions of a true circuit, as the
internal circuit, or external circuit. A certain amount of elasticity is
allowed in its use. It by no means necessarily indicates a complete
through circuit.


Circuit, Electrostatic.
(a) A circuit through which an electrostatic or high tension discharge
takes place. It is virtually an electric circuit.

(b) The term is applied also to the closed paths of electrostatic lines
of force.


Circuit, External.
The portion of a circuit not included within the generator.


Circuit, Grounded.
A circuit, one of whose members, the return circuit, is represented by
the earth, so that the earth completes the circuit. In telegraphy each
end of the line is grounded or connected to an earth-plate, q. v., or to
the water or gas-pipes, and the current is assumed to go through the
earth on its return. It really amounts to a discharging at one end, and
charging at the other end of the line. The resistance of the earth is
zero, but the resistance of the grounding or connection with the earth
may be considerable.

Synonyms--Ground Circuit--Earth Circuit--Single Wire Circuit.

[Transcriber's note: The resistance of the earth is high enough that
large power system return currents may produce dangerous voltage
gradients when a power line is shorted to the ground. Don't walk near
downed lines!]


124   STANDARD ELECTRICAL DICTIONARY.


Circuit Indicator.
A pocket compass, decomposition apparatus, galvanometer or other device
for indicating the condition of a wire, whether carrying a current or
not, and, if carrying one, its direction, and sometimes roughly
indicating its strength.


Circuit, Internal.
The portion of an electric circuit included within the generator.


Circuit, Line.
The portion of a circuit embracing the main line or conductor, as in a
telegraph circuit the line carried on the poles; distinguished from the
local circuit (see Circuit, Local,) in telegraphy.


Circuit, Local.
In telegraphy, a short circuit with local generator or battery included,
contained within the limits of the office or station and operated by a
relay, q. v. This was the original local circuit; the term is applicable
to any similar arrangement in other systems. Referring to the cut, the
main line circuit includes the main battery, E, Key, P, Relay, R, ground
plates, G, G1. The relay magnet opens and closes the local circuit with
its local battery, L, and sounder magnet, H, with its armature, B. The
minor parts, such as switches, are omitted.



Fig. 90. LOCAL CIRCUIT OF TELEGRAPH SYSTEM.


Circuit, Local Battery.
A local circuit worked by and including a local battery in its course.


125   STANDARD ELECTRICAL DICTIONARY.


Circuit, Loop.
A minor circuit introduced in series into another circuit by a cut-out,
or other device, so as to become a portion of the main circuit.


Circuit Loop Break.
A supporter or bracket with two arms for carrying insulators. Its use is
to enable a loop connection to be introduced into a line which is cut,
so as to enable the connection of the ends of the loop to be made, one
to each end of the through wire, which ends are attached, one to each of
the two insulators.


Circuit, Main.
The circuit including the main line and apparatus supplied by the main
battery, as distinguished from the local circuit. (See Circuit, Local.)


Circuit, Main Battery.
The main circuit, including the main or principal battery in its course.


Circuit, Metallic.
A circuit in which the current outside the generator, or similar parts,
is carried on a metallic conductor; a circuit without any ground
circuit. The including of a galvanic battery or electro plating bath
would not prevent the application of the term; its essential meaning is
the omission of the earth as the return circuit.


Circuit, Negative Side of.
The side of a circuit opposite to the positive side. (See Circuit,
Positive Side of) It is defined as the half of a circuit leading to the
positive terminal of the generator.


Circuit, Open.
A circuit with its continuity broken, as by disconnecting a wire from
the battery, or opening a switch; a broken circuit is its synonym. To
open a switch or disconnect or cut the wire is termed opening or
breaking the circuit.

Synonyms--Incomplete Circuit--Broken Circuit.


Circuit, Positive Side of.
This side is such that an observer standing girdled by the current with
his head in the positive side or region, would see the current pass
around him from his right toward his left hand. It is also defined as
the half of the circuit leading to the negative terminal of the
generator.


Circuit, Recoil.
The portion of a parallel circuit presenting an alternative path, q. v.,
for a disruptive discharge.


Circuit, Return.
(a) The part of a circuit extending from the generator to the extreme
point in general, upon which no apparatus is placed. In telegraph
systems the ground generally forms the return circuit. The distinction
of return and working circuit cannot always be made.

(b) It may also be defined as the portion of a circuit leading to the
negative terminal of the generator.


126   STANDARD ELECTRICAL DICTIONARY


Circuits, Forked.
Circuits starting in different paths or directions from one and the same
point.


Circuit, Simple.
A circuit containing a single generator, and single receiver of any
kind, such as a motor or sounder, with a single connecting conductor. It
is also used to indicate arrangement in multiple arc, but not generally,
or with approval.


Circuits, Parallel.
Two or more conductors starting from a common point and ending at
another common point are termed, parallel circuits, although really but
parts of circuits. If of equal resistance their joint resistance is
obtained by dividing the resistance of one by the number of parallel
circuits. If of unequal resistance r, r', r" , etc., the formula for
joint resistance, R, of two is

R = ( r * r' ) / ( r + r' )

This resistance may then be combined with a third one by the same
formula, and thus any number may be calculated.

Synonym--Shunt Circuit.


Circuit, Voltaic.
Properly a circuit including a conductor and voltaic couple.

It is also applied to the electric circuit, q. v., or to any circuit
considered as a bearer of current electricity.


Circular Units.
Units of area, usually applied to cross sectional area of conductors, by
whose use area is expressed in terms of  circle of unit diameter,
usually a circular mil, which is the area of a circle of one-thousandth
of an inch diameter, or a circular millimeter, which is the area of a
circle of one millimeter diameter. Thus a wire one-quarter of an inch
in diameter has an area of 250 circular mils; a bar one centimeter in
diameter has an area of ten circular millimeters.

[Transcriber's Note: Area is the diameter squared. A 1/4 inch wire has
62500 circular mils of area. A one centimeter (10 millimeter) wire has
100 circular millimeters of area. Actual area = circular mils * (PI/4).]


Circumflux.
The product of the total number of conductor turns on the armature of a
dynamo or motor, into the current carried thereby. For two pole machines
it is equal to twice the armature ampere-turns; for four pole machines
to four times such quantity, and so on.


Clamp.
The appliance for grasping and retaining the end of the rod that holds a
carbon in the arc lamp.

Clark's Compound.
A cement used for the outside of the sheath of telegraph cables.
Its formula is:
  Mineral Pitch,   65 parts.
  Silica,          30 parts.
  Tar,              5 parts.
All parts by weight.


127  STANDARD ELECTRICAL DICTIONARY.


Cleats.
A support; a short block of wood, grooved transversely, for holding
electric wires against a wall. For the three wire system three grooves
are used. The entire wiring of apartments is sometimes done by the
"cleat system," using cleats instead of battens, q. v., or mouldings.
The cleats are secured against the wall with the grooves facing it, and
the wires are introduced therein.



Fig. 91. TWO WIRE CLEAT.



Fig. 92. THREE WIRE CLEAT.


Cleat, Crossing.
A cleat with grooves or apertures to support wires which cross each
other. Two or three grooves are transverse, and on the under side, as
above; one groove is longitudinal and on the upper side.


Cleavage, Electrification by.
If a mass of mica is rapidly split in the dark a slight flash is
perceived. Becquerel found that in such separation the two pieces came
away oppositely charged with electricity. The splitting of mica is its
cleavage.


Clock, Controlled.
In a system of electric clocks, the clocks whose movements are
controlled by the current, regulated by the master or controlling clock.

Synonym--Secondary Clock.


Clock, Controlling.
In a system of electric clocks the master clock which controls the
movements of the others, by regulating the current.

Synonym--Master Clock.


Clock, Electric Annunciator.
A clock operating any form of electric annunciator, as dropping
shutters, ringing bells, and the like. It operates by the machinery
closing circuits as required at any desired hour or intervals.


128   STANDARD ELECTRICAL DICTIONARY.


Clock, Electrolytic.
A clock worked by the electrolytic deposition and resolution of a
deposit of metal upon a disc. It is the invention of Nikola Tesla. A
metallic disc is mounted on a transverse axis, so as to readily rotate.
It is immersed in a vessel of copper sulphate. A current is passed
through the bath, the terminals or electrodes being near to and facing
the opposite edges of the disc, so that the line connecting the
electrodes lies in the plane of the disc. If a current is passed through
the solution by the electrodes, copper is de

Coils, Compensating.
Extra coils on the field magnets of dynamos or motors, which coils are
in series with the armature windings for the purpose of keeping the
voltage constant. In compound wound machines the regular series-wound
coil is thus termed. In a separately excited dynamo a coil of the same
kind in circuit with the armature may be used as a compensator.


Coils, Henry's.
An apparatus used in repeating a classic experiment in electro-magnetic
induction, due to Prof. Henry. It consists in a number of coils, the
first and last ones single, the intermediate ones connected in pairs,
and one of one pair placed on the top of one of the next pair. On
opening or closing the circuit of an end coil the induced effect goes
through the series and is felt in the circuit of the other end coil.
Prof. Henry extended the series so as to include seven successive
inductions, sometimes called inductions of the first, second, third and
other orders. Frequently ribbon coils (see Coil, Ribbon,) are used in
these experiments.


Coils, Sectioned.
A device for prolonging the range of magnetic attraction. It consists of
a series of magnetizing coils traversed by an iron plunger. As it passes
through them, the current is turned off the one in the rear or passing
to the rear and turned into the next one in advance. The principle was
utilized in one of Page's electric motors about 1850, and later by
others. The port-electric railroad, q. v., utilizes the same principle.


139  STANDARD ELECTRICAL DICTIONARY.


Collecting Ring.
In some kinds of generators instead of the commutator a pair of
collecting rings of metal, insulated from the machine and from each
other, are carried on the armature shaft. A brush, q. v., presses on
each, and the circuit terminals connect to these two brushes. Such rings
are employed often on alternating current generators, where the current
does not have to be changed or commuted. Collecting rings with their
brushes are used also where a current has to be communicated to a
revolving coil or circuit as in the magnetic car wheel, the cut of which
is repeated here. The coil of wire surrounding the wheel and rotating
with it has to receive current. This it receives through the two
stationary brushes which press upon two insulated metallic rings,
surrounding the shaft. The terminals of the coil connect one to each
ring. Thus while the coil rotates it constantly receives current, the
brushes being connected to the actuating circuit.



Fig. 105. MAGNETIC CAR WHEEL SHOWING
COLLECTING RINGS AND BRUSHES.


Collector.
(a) A name for the brush, q. v., in mechanical electric generators, such
as dynamos, a pair of which collectors or brushes press on the
commutator or collecting rings, and take off the current.

(b) The pointed connections leading to the prime conductor on a static
machine for collecting the electricity; often called combs. The points
of the combs or collectors face the statically charged rotating glass
plate or cylinder of the machine.


Colombin.
The insulating material between the carbons in a Jablochkoff candle or
other candle of that type. Kaolin was originally used. Later a mixture
of two parts calcium sulphate (plaster of Paris) and one part barium
sulphate (barytes) was substituted.

The colombin was three millimeters (.12 inch) wide, and two millimeters
(.08 inch) thick. (See Candle, Jablochkoff.)


Column, Electric.
An old name for the voltaic pile, made up of a pile of discs of copper
and zinc, with flannel discs, wet with salt solution or dilute acid,
between each pair of plates.


140   STANDARD ELECTRICAL DICTIONARY.


Comb.
A bar from which a number of teeth project, like the teeth of a comb. It
is used as a collector of electricity from the plate of a frictional or
influence electric machine; it is also used in a lightning arrester to
define a path of very high resistance but of low self-induction, for the
lightning to follow to earth.


Communicator.
The instrument by which telegraph signals are transmitted is sometimes
thus termed.


Commutator.
In general an apparatus for changing. It is used on electric current
generators, and motors, and on induction coils, and elsewhere, for
changing the direction of currents, and is of a great variety of types.

Synonym--Commuter (but little used).



Fig. 106. DYNAMO OR MOTOR COMMUTATOR.


Commutator Bars.
The metallic segments of a dynamo or motor commutator.


Commutator, Flats in.
A wearing away or lowering in level of one or more metallic segments of
a commutator. They are probably due in many cases to sparking, set up by
periodic springing in the armature mounting, or by defective commutator
connections.


Commutator of Current Generators and Motors.
In general a cylinder, formed of alternate sections of conducting and
non-conducting material, running longitudinally or parallel with the
axis. Its place is on the shaft of the machine, so that it rotates
therewith. Two brushes, q. v., or pieces of conducting material, press
upon its surface.


141  STANDARD ELECTRICAL DICTIONARY.


As a part of electric motors and generators, its function is to collect
the currents produced by the cutting of lines of force so as to cause
them all to concur to a desired result. The cut shows the simplest form
of commutator, one with but two divisions. Its object may be to enable a
current of constant direction to be taken from a rotating armature, in
which the currents alternate or change direction once in each rotation.
It is carried by the shaft A of the armature and rotates with it. It
consists of two leaves, S S, to which the terminals of the armature are
connected. Two springs, W W, the terminals of the outer circuit, press
against the leaves. The springs which do this take off the current. It
is so placed, with reference to the springs and armature, that just as
the current changes in direction, each leaf changes from one spring to
the other. Thus the springs receive constant direction currents. The
changing action of this commutator appears in its changing the character
of the current from alternating to constant. Were two insulated
collecting rings used instead of a commutator, the current in the outer
circuit would be an alternating one. On some dynamos the commutator has
a very large number of leaves.

Taking the Gramme ring armature, there must be as many divisions of the
commutator as there are connections to the coils. In this case the
function of the commutator is simply to lessen friction, for the brushes
could be made to take current from the coils directly outside of the
periphery of the ring.


Commutator, Split Ring.
A two-division commutator for a motor; it consists of two segments of
brass or copper plate, bent to arcs of a circle, and attached to an
insulating cylinder. They are mounted on the revolving spindle, which
carries the armature, and acts as a two part commutator. For an example
of its application, see Armature, Revolving, Page's. (See also Fig.
107.)



Fig. 107. SECTION OF SPLIT RING COMMUTATOR, WITH BRUSHES.


Compass.
An apparatus for utilizing the directive force of the earth upon the
magnetic needle. It consists of a circular case, within which is poised
a magnetized bar of steel. This points approximately to the north, and
is used on ships and elsewhere to constantly show the direction of the
magnetic meridian. Two general types are used. In one the needle is
mounted above a fixed "card" or dial, on which degrees or points of the
compass, q. v., are inscribed. In the other the card is attached to the
needle and rotates with it. The latter represents especially the type
known as the mariner's compass. (See Compass, Mariner's--Compass,
Spirit, and other titles under compass, also Magnetic Axis--Magnetic
Elements.) The needle in good compasses carries for a bearing at its
centre, a little agate cup, and a sharp brass pin is the point of
support.


Compass, Azimuth.
A compass with sights on one of its diameters; used in determining the
magnetic bearing of objects.


142   STANDARD ELECTRICAL DICTIONARY.


Compass Card.
The card in a compass; it is circular in shape, and its centre coincides
with the axis of rotation of the magnetic needle; on it are marked the
points of the compass, at the ends generally of star points. (See
Compass, Points of the.) It may be fixed, and the needle may be poised
above it, or it may be attached to the needle and rotate with it.


Compass, Declination.
An instrument by which the magnetic declination of any place may be
determined. It is virtually a transit instrument and compass combined,
the telescope surmounting the latter. In the instrument shown in the
cut, L is a telescope mounted by its axis, X, in raised journals with
vernier, K, and arc x, for reading its vertical angle, with level n. The
azimuth circle, Q, R, is fixed. A vernier, V is carried by the box, A,
E, and both turn with the telescope. A very light lozenge-shaped
magnetic needle, a, b, is pivoted in the exact centre of the graduated
circles, Q R, and M. The true meridian is determined by any convenient
astronomical method, and the telescope is used for the purpose. The
variation of the needle from the meridian thus determined gives the
magnetic declination.



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 wit

takes place, but which is considerably retarded, while electrolysis and
electrolytic convection take place freely through its walls. As
material, unglazed pottery is very generally used.

In some batteries the cup is merely a receptacle for the solid
depolarizer. Thus, in the LeclanchÉ battery, the cup contains the
manganese dioxide and graphite in which the carbon electrode is
embedded, but does not separate two solutions, as the battery only uses
one. Nevertheless, the composition of the solution outside and inside
may vary, but such variation is incidental only, and not an essential of
the operation.


Current.
The adjustment, or effects of a continuous attempt at readjustment of
potential difference by a conductor, q. v., connecting two points of
different potential. A charged particle or body placed in a field of
force tends to move toward the oppositely charged end or portion of the
field. If a series of conducting particles or a conducting body are held
so as to be unable to move, then the charge of the field tends, as it
were, to move through it, and a current results. It is really a
redistribution of the field and as long as such redistribution continues
a current exists. A current is assumed to flow from a positive to a
negative terminal; as in the case of a battery, the current in the outer
circuit is assumed to flow from the carbon to the zinc plate, and in the
solution to continue from zinc to carbon. As a memoria technica the zinc
may be thought of as generating the current delivering it through the
solution to the carbon, whence it flows through the wire connecting
them. (See Ohm's Law--Maxwell's Theory of Light--Conductor-Intensity.)

[Transcriber's note: Supposing electric current to be the motion of
positive charge causes no practical difficulty, but the current is
actually the (slight) motion of negative electrons.]


Current, After.
A current produced by the animal tissue after it has been subjected to a
current in the opposite direction for some time. The tissue acts like a
secondary battery. The term is used in electro-therapeutics.


Current, Alternating.
Usually defined and spoken of as a current flowing alternately in
opposite directions. It may be considered as a succession of currents,
each of short duration and of direction opposite to that of its
predecessor. It is graphically represented by such a curve as shown in
the cut. The horizontal line may denote a zero current, that is no
current at all, or may be taken to indicate zero electro-motive force.
The curve represents the current, or the corresponding electro-motive
forces. The further from the horizontal line the greater is either, and
if above the line the direction is opposite to that corresponding to the
positions below the line. Thus the current is alternately in opposite
directions, has periods of maximum intensity, first in one and then in
the opposite sense, and between these, passing from one direction to the
other, is of zero intensity. It is obvious that the current may rise
quickly in intensity and fall slowly, or the reverse, or may rise and
fall irregularly. All such phases may be shown by the curve, and a curve
drawn to correctly represent these variations is called the
characteristic curve of such current. It is immaterial whether the
ordinates of the curve be taken as representing current strength or
electromotive force. If interpreted as representing electro-motive
force, the usual interpretation and best, the ordinates above the line
are taken as positive and those below as negative.

Synonyms--Reversed Current--Periodic Currents.



Fig. 117. CHARACTERISTIC CURVE OF ALTERNATING CURRENT.


160   STANDARD ELECTRICAL DICTIONARY.


Current, Atomic.
A unit of current strength used in Germany; the strength of a current
which will liberate in 24 hours (86,400 seconds) one gram of hydrogen
gas, in a water voltameter. The atomic current is equal to 1.111
amperes. In telegraphic work the milliatom is used as a unit, comparable
to the milliampere. The latter is now displacing it.


Current, Charge.
If the external coatings of a charged and uncharged jar are placed in
connection, and if the inner coatings are now connected, after
separating them they are both found to be charged in the same manner. In
this process a current has been produced between the outside coatings
and one between the inner ones, to which Dove has given the name Charge
Current, and which has all the properties of the ordinary discharge
current. (Ganot.)


Current, Circular.
A current passing through a circular conductor; a current whose path is
in the shape of a circle.


Current, Commuted.
A current changed, as regards direction or directions, by a commutator,
q. v., or its equivalent.


Current, Constant.
An unvarying current. A constant current system is one maintaining such
a current. In electric series, incandescent lighting, a constant current
is employed, and the system is termed as above. In arc lighting systems,
the constant current series arrangement is almost universal.


161  STANDARD ELECTRICAL DICTIONARY.


Current, Continuous.
A current of one direction only; the reverse of an alternating current.
(See Current, Alternating.)


Current, Critical.
The current produced by a dynamo at its critical speed; at that speed
when a slight difference in speed produces a great difference in
electro-motive force. On the characteristic curve it corresponds to the
point where the curve bends sharply, and where the electro-motive force
is about two-thirds its maximum.


Current, Daniell/U.S. , Daniell/Siemens' Unit.
A unit of current strength used in Germany. It is the strength of a
current produced by one Daniell cell in a circuit of the resistance of
one Siemens' unit. The current deposits 1.38 grams of copper per hour.
It is equal to 1.16 amperes.


Current, Demarcation.
In electro-therapeutics, a current which can be taken from an injured
muscle, the injured portion acting electro-negatively toward the
uninjured portion.


Current Density.
The current intensity per unit of cross-sectional area of the conductor.
The expression is more generally used for electrolytic conduction, where
the current-density is referred to the mean facing areas of the
electrodes, or else to the facing area of the cathode only.

The quality of the deposited metal is intimately related to the current
density. (See Burning.)

              Proper Current Density for Electroplating
           Amperes Per Square Foot of Cathode.--(Urquhart.)
Copper, Acid Bath.                               5.0  to 10.0
"       Cyanide Bath,                            3.0  "   5.0
Silver, Double Cyanide,                          2.0  "   5.0
Gold, Chloride dissolved in Potassium Cyanide,   1.0  "   2.0
Nickel, Double Sulphate,                         6.6  "   8.0
Brass, Cyanide,                                  2.0  "   3.0


Current, Diacritical.
A current, which, passing through a helix surrounding an iron core,
brings it to one-half its magnetic saturation, q. v.


Current, Diaphragm.
If a liquid is forced through a diaphragm, a potential difference
between the liquid on opposite sides of the diaphragm is maintained.
Electrodes or terminals of platinum may be immersed in the liquid, and a
continuous current, termed a diaphragm current, may be taken as long as
the liquid is forced through the diaphragm. The potential difference is
proportional to the pressure, and also depends on the nature of the
diaphragm and on the liquid.


162   STANDARD ELECTRICAL DICTIONARY.


Current, Direct.
A current of unvarying direction, as distinguished from an alternating
current. It may be pulsatory or intermittent in character, but must be
of constant direction.


Current, Direct Induced.
On breaking a circuit, if it is susceptible of exercising
self-induction, q. v., an extra current, in the direction of the
original is induced, which is called "direct" because in the same
direction as the original. The same is produced by a current in one
circuit upon a parallel one altogether separated from it. (See
Induction, Electro-Magnetic-Current, Extra.)

Synonym--Break Induced Current.


Current, Direction of.
The assumed direction of a current is from positively charged electrode
to negatively charged one; in a galvanic battery from the carbon or
copper plate through the outer circuit to the zinc plate and back
through the electrolyte to the carbon or copper plate. (See Current.)

[Transcriber's note: Current is caused by the motion of negative
electrons, from the negative pole to the positive. The electron was
discovered five years after this publication.]


Current, Displacement.
The movement or current of electricity taking place in a dielectric
during displacement. It is theoretical only and can only be assumed to
be of infinitely short duration. (See Displacement, Electric.)


Currents, Eddy Displacement.
The analogues of Foucault currents, hypothetically produced in the mass
of a dielectric by the separation of the electricity or by its
electrification. (See Displacement.)


Current, Extra.
When a circuit is suddenly opened or closed a current of very brief
duration, in the first case in the same direction, in the other case in
the opposite direction, is produced, which exceeds the ordinary current
in intensity. A high potential difference is produced for an instant
only. These are called extra currents. As they are produced by
electro-magnetic induction, anything which strengthens the field of
force increases the potential difference to which they are due. Thus the
wire may be wound in a coil around an iron core, in which case the extra
currents may be very strong. (See Induction, Self-Coil, Spark.)


Current, Faradic.
A term in medical electricity for the induced or secondary alternating
current, produced by comparatively high electro-motive force, such as
given by an induction coil or magneto-generator, as distinguished from
the regular battery current.


163   STANDARD ELECTRICAL DICTIONARY.


Current, Foucault.
A current produced in solid conductors, and which is converted into heat
(Ganot). These currents are produced by moving the conductors through a
field, or by altering the strength of a field in which they are
contained. They are the source of much loss of energy and other
derangement in dynamos and motors, and to avoid them the armature cores
are laminated, the plane of the laminations being parallel to the lines
of force. (See Core, Laminated.)

The presence of Foucault currents, if of long duration, is shown by the
heating of the metal in which they are produced. In dynamo armatures
they are produced sometimes in the metal of the windings, especially if
the latter are of large diameter.

Synonyms--Eddy Currents--Local Currents--Parasitical Currents.


Current, Franklinic.
In electro-therapeutics the current produced by a frictional electric
machine.


Current, Induced.
The current produced in a conductor by varying the conditions of a field
of force in which it is placed; a current produced by induction.


Current Induction.
Induction by one current on another or by a portion of a current on
another portion of itself. (See Induction.)


Current Intensity.
Current strength, dependent on or defined by the quantity of electricity
passed by such current in a given time. The practical unit of current
intensity is the ampere, equal to one coulomb of quantity per second of
time.


Current, Inverse Induced.
The current induced in a conductor, when in a parallel conductor or in
one having a parallel component a current is started, or is increased in
strength. It is opposite in direction to the inducing current and hence
is termed inverse. (See Induction, Electro-magnetic.) The parallel
conductors may be in one circuit or in two separate circuits.

Synonyms--Make-induced Current--Reverse-induced Current.


Current, Jacobi's Unit of.
A current which will liberate one cubic centimeter of mixed gases
(hydrogen and oxygen) in a water voltameter per minute, the gases being
measured at 0º C. (32º F.) and 760 mm. (29.92 inches) barometric
pressure. It is equal to .0961 ampere.


Current, Joint.
The current given by several sources acting together. Properly, it
should be restricted to sources connected in series, thus if two battery
cells are connected in series the current they maintain is their joint
current.


Current, Linear.
A current passing through a straight conductor; a current whose path
follows a straight line.


164   STANDARD ELECTRICAL DICTIONARY.


Current, Make and Break.
A succession of currents of short duration, separated by absolute
cessation of current. Such current is produced by a telegraph key, or by
a microphone badly adjusted, so that the circuit is broken at intervals.
The U. S. Courts have virtually decided that the telephone operates by
the undulatory currents, and not by a make and break current. Many
attempts have been made to produce a telephone operating by a
demonstrable make and break current, on account of the above
distinction, in hopes of producing a telephone outside of the scope of
the Bell telephone patent.

[Transcriber's note: Contemporary long distance telephone service is
digital, as this item describes.]


Current-meter.
An apparatus for indicating the strength of current. (See Ammeter.)


Current, Negative.
In the single needle telegraph system the current which deflects the
needle to the left.


Current, Nerve and Muscle.
A current of electricity yielded by nerves or muscles. Under proper
conditions feeble currents can be taken from nerves, as the same can be
taken from muscles.


Current, Opposed.
The current given by two or more sources connected in opposition to each
other. Thus a two volt and a one volt battery may be connected in
opposition, giving a net voltage of only one volt, and a current due to
such net voltage.


Current, Partial.
A divided or branch current. A current which goes through a single
conductor to a point where one or more other conductors join it in
parallel, and then divides itself between the several conductors, which
must join further on, produces partial currents. It produces as many
partial currents as the conductors among which it divides. The point of
division is termed the point of derivation.

Synonym--Derived Current.


Current, Polarizing.
In electro-therapeutics, a constant current.


Current, Positive.
In the single needle telegraph system the current which deflects the
needle to the right.


Current, Pulsatory.
A current of constant direction, but whose strength is constantly
varying, so that it is a series of pulsations of current instead of a
steady flow.

Current, Rectified.
A typical alternating current is represented by a sine curve, whose
undulations extend above and below the zero line. If by a simple two
member commutator the currents are caused to go in one direction, in
place of the sine curve a series of short convex curves following one
another and all the same side of the zero line results. The currents all
in the same direction, become what is known as a pulsating current.

Synonym--Redressed Current.


165  STANDARD ELECTRICAL DICTIONARY.


Current, Rectilinear.
A current flowing through a rectilinear conductor. The action of
currents depending on their distance from the points where they act,
their contour is a controlling factor. This contour is determined by the
conductors through which they flow.


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


Currents, AmpÉrian.
The currents of electricity assumed by Ampere's theory to circulate
around a magnet. As they represent the maintenance of a current or of
currents without the expenditure of energy they are often assumed to be
of molecular dimensions. As they all go in the same sense of rotation
and are parallel to each other the result is the same as if a single set
of currents circulated around the body of the magnet. More will be found
on this subject under Magnetism. The AmpÉrian currents are purely
hypothetical and are predicated on the existence of a field of force
about a permanent magnet. (See Magnetism, AmpÉre's Theory of.)

If the observer faces the north pole of a magnet the AmpÉrian currents
are assumed to go in the direction opposite to that of a watch, and the
reverse for the south pole.



Figs. 118-119 DIRECTION OF AMPÉRIAN CURRENTS.


Currents, Angular.
Currents passing through conductors which form an angle with each other.


Currents, Angular, Laws of.
1. Two rectilinear currents, the directions of which form an angle with
each other, attract one another when both approach to or recede from the
apex of the angle.

2. They repel one another, if one approaches and the other recedes from
the apex of the angle.


166   STANDARD ELECTRICAL DICTIONARY


Currents, Earth.
In long telegraph lines having terminal grounds or connected to earth
only at their ends, potential differences are sometimes observed that
are sufficient to interfere with their working and which, of course, can
produce currents. These are termed earth-currents. It will be noted that
they exist in the wire, not in the earth. They may be of 40 milliamperes
strength, quite enough to work a telegraph line without any battery.
Lines running N. E. and S. W. are most affected; those running N.W. and
S. E. very much less so. These currents only exist in lines grounded at
both ends, and appear in underground wires. Hence they are not
attributable to atmospheric electricity. According to Wilde they are the
primary cause of magnetic storms, q. v., but not of the periodical
changes in the magnetic elements. (See Magnetic Elements.)

Synonym--Natural Currents.


Current, Secondary.
(a) A current induced in one conductor by a variation in the current in
a neighboring one; the current produced in the secondary circuit of an
induction coil or alternating current converter.

(b) The current given by a secondary battery. This terminology is not to
be recommended.


Current, Secretion.
In electro-therapeutics, a current due to stimulation of the secretory
nerves.


Current Sheet.
(a) If two terminals of an active circuit are connected to two points of
a thin metallic plate the current spreads over or occupies practically a
considerable area of such plate, and this portion of the current is a
current sheet.

The general contour of the current sheet can be laid out in lines of
flux. Such lines resemble lines of force. Like the latter, they are
purely an assumption, as the current is not in any sense composed  of
lines.

(b) A condition of current theoretically brought about by the AmpÉrian
currents in a magnet. Each molecule having its own current, the
contiguous portions of the molecules counteract each other and give a
resultant zero current. All that remains is the outer sheet of electric
current that surrounds the whole.


Current, Sinuous.
A current passing through a sinuous conductor.


Currents, Multiphase.
A term applied to groups of currents of alternating type which
constantly differ from each other by a constant proportion of periods of
alternation. They are produced on a single dynamo, the winding being so
contrived that two, three or more currents differing a constant amount
in phase are collected from corresponding contact rings. There are
virtually as many windings on the armature as there are currents to be
produced. Separate conductors for the currents must be used throughout.

Synonyms--Polyphase Currents--Rotatory Currents.


167  STANDARD ELECTRICAL DICTIONARY.


Currents of Motion.
In electro-therapeutics, the currents produced in living muscle or
nerves after sudden contraction or relaxation.


Currents of Rest.
In electro-therapeutics, the currents traversing muscular or nervous
tissue when at rest. Their existence is disputed.


Currents, Orders of.
An intermittent current passing through a conductor will induce
secondary alternating currents in a closed circuit near it. This
secondary current will induce a tertiary current in a third closed
circuit near it, and so on. The induced currents are termed as of the
first, second, third and other orders. The experiment is carried out by
Henry's coils. (See Coils, Henry's.)


Currents, Thermo-electric.
These currents, as produced from existing thermo-electric batteries,
are generated by low potential, and are of great constancy. The opposite
junctions of the plates can be kept at constant temperatures, as by
melting ice and condensing steam, so that an identical current can be
reproduced at will from a thermopile.

Thermo-electric currents were used by Ohm in establishing his law. (See
Ohm's Law.)


Current, Swelling.
In electro-therapeutics, a current gradually increasing in strength.


Current, Undulatory.
A current varying in strength without any abrupt transition from action
to inaction, as in the make and break current. The current may be
continually changing in direction (see Current, Alternating), and hence,
of necessity, may pass through stages of zero intensity, but such
transition must be by a graduation, not by an abrupt transition. Such
current may be represented by a curve, such as the curve of sines. It is
evident that the current may pass through the zero point as it crosses
the line or changes direction without being a make and break current.
When such a current does alternate in direction it is sometimes called a
"shuttle current." The ordinary commercial telephone current and the
alternating current is of this type. (See Current, Make and Break.)


Current, Unit.
Unit current is one which in a wire of unit length, bent so as to form
an arc of a circle of unit length of radius, would act upon a unit pole
(see Magnetic Pole, Unit,) at the center of the circle with unit force.
Unit length is the centimeter; unit force is the dyne.

[Transcriber's note: The SI definition of an ampere: A current in two
straight parallel conductors of infinite length and negligible
cross-section, 1 metre apart in vacuum, would produce a force equal to
2E-7 newton per metre of length.]


168   STANDARD ELECTRICAL DICTIONARY.


Current, Wattless.
Whenever there is a great difference in phase in an alternating current
dynamo between volts and current, the true watts are much less than the
product of the virtual volts and amperes, because the the watts are
obtained by multiplying the product of the virtual volts and amperes by
the cosine of the angle of lag (or lead). Any alternating current may be
resolved into two components in quadrature with each other, one in phase
with the volts, the other in quadrature therewith, the former is termed
by S. P. Thompson the Working Current, the latter the Wattless Current.
The greater the angle of lag the greater will be the wattless current.


Curve, Arrival.
A curve representing the rate of rise of intensity of current at the end
of a long conductor when the circuit has been closed at the other end.
In the Atlantic cable, for instance, it would require about 108 seconds
for the current at the distant end to attain 9/10 of its full value. The
curve is drawn with its abscissa representing time and its ordinates
current strength.


Curve, Characteristic.
A curve indicating, graphically, the relations between any two factors,
which are interdependent, or which vary simultaneously. Thus in a
dynamo, the voltage increases with the speed of rotation, and a
characteristic curve may be based on the relations between the speed of
rotation and voltage developed. The current produced by a dynamo varies
with the electro-motive force, and a curve can express the relations
between the electro-motive force and the current produced.

A characteristic curve is usually laid out by rectangular co-ordinates
(see Co-ordinates). Two lines are drawn at right angles to each other,
one vertical, and the other horizontal. One set of data are marked off
on the horizontal line, say one ampere, two amperes, and so on, in the
case of a dynamo's characteristic curve.

For each amperage of current there is a corresponding voltage in the
circuit. Therefore on each ampere mark a vertical is erected, and on
that the voltage corresponding to such amperage is laid off. This gives
a series of points, and these points may be connected by a curve. Such
curve will be a characteristic curve.

The more usual way of laying out a curve is to work directly upon the
two axes. On one is laid off the series of values of one set of data; on
the other the corresponding series of values of the other dependent
data. Vertical lines or ordinates, q. v., are erected on the horizontal
line or axis of abscissas at the points laid off; horizontal lines or
abscissas, q. v., are drawn from the points laid off on the vertical
line or axis of ordinates. The characteristic curve is determined by the
intersections of each corresponding pair of abscissa and ordinate.


169  STANDARD ELECTRICAL DICTIONARY.


Variations exist in characteristic curve methods. Thus to get the
characteristic of a commutator, radial lines may be drawn from a circle
representing its perimeter. Such lines may be of length proportional to
the voltage developed on the commutator at the points whence the lines
start. A cut giving an example of such a curve is given in Fig. 125.
(See Curve of Distribution of Potential in Armature.)

There is nothing absolute in the use of ordinates or abscissas. They may
be interchanged. Ordinarily voltages are laid off as ordinates, but the
practise may be reversed. The same liberty holds good for all
characteristic curves. Custom, however, should be followed.

Synonym--Characteristic.



Fig. 120. CHARACTERISTIC CURVE OF A DYNAMO
WITH HORSE POWER CURVES.


Curve, Characteristic, of Converter.
The characteristic curve of the secondary circuit of an alternating
current converter. It gives by the usual methods (see Curve,
Characteristic,) the relations between the electro-motive force and the
current in the secondary circuit at a fixed resistance. If connected in
parallel a constant electro-motive force is maintained, and the curve is
virtually a straight line. If connected in series an elliptical curve is
produced.


170   STANDARD ELECTRICAL DICTIONARY.


Curve, Charging.
In secondary battery manipulation, a curve indicating the increase of
voltage as the charging is prolonged. The rise in voltage with the
duration of the charging current is not uniform. In one case, shown in
the cut, there was a brief rapid rise of about 0.1 volt; then a long
slow rise for 0.15 volt; then a more rapid rise for nearly 0.40 volt,
and then the curve became a horizontal line indicating a cessation of
increase of voltage. The charging rate should be constant.

The horizontal line is laid off in hours, the vertical in volts, so that
the time is represented by abscissas and the voltage by ordinates of the
curve.



Fig. 121. CHARGING CURVE OF A SECONDARY BATTERY.


Curve, Discharging.
A characteristic curve of a storage battery, indicating the fall in
voltage with hours of discharge. The volts may be laid off on the axis
of ordinates, and the hours of discharging on the axis of abscissas. To


176   STANDARD ELECTRICAL DICTIONARY.


Damper.
(a) A copper frame on which the wire in a galvanometer is sometimes
coiled, which acts to damp the oscillations of the needle.

(b) A tube of brass or copper placed between the primary and secondary
coils of an induction coil. It cuts off induction and diminishes the
current and potential of the secondary circuit. On pulling it out, the
latter increases. It is used on medical coils to adjust their strength
of action.


Damping.
Preventing the indicator of an instrument from oscillating in virtue of
its own inertia or elasticity. In a galvanometer it is defined as
resistance to quick vibrations of the needle, in consequence of which it
is rapidly brought to rest when deflected (Ayrton). In dead-beat
galvanometers (see Galvanometer, Dead-Beat,) damping is desirable in
order to bring the needle to rest quickly; in ballistic galvanometers
(see Galvanometer, Ballistic,) damping is avoided in order to maintain
the principle of the instrument. Damping may be mechanical, the
frictional resistance of air to an air-vane, or of a liquid to an
immersed diaphragm or loosely fitting piston, being employed. A
dash-pot, q. v., is an example of the latter. It may be
electro-magnetic. A mass of metal near a swinging magnetic needle tends
by induced currents to arrest the oscillations thereof, and is used for
this purpose in dead-beat galvanometers. This is termed, sometimes,
magnetic friction. The essence of damping is to develop resistance to
movement in some ratio proportional to velocity, so that no resistance
is offered to the indicator slowly taking its true position. (See
Galvanometer, Dead-Beat.)


Dash-Pot.
A cylinder and piston, the latter loosely fitting or perforated, or some
equivalent means being provided to permit movement. The cylinder may
contain a liquid such as glycerine, or air only. Thus the piston is
perfectly free to move, but any oscillations are damped (see Damping).
In some arc lamps the carbon holder is connected to a dash-pot to check
too sudden movements of the carbon. The attachment may be either to the
piston or to the cylinder. In the Brush lamp the top of the carbon
holder forms a cylinder containing glycerine, and in it a loosely
fitting piston works. This acts as a dash-pot.


Dead Beat. adj.
Reaching its reading quickly; applied to instruments having a moving
indicator, which normally would oscillate back and forth a number of
times before reaching its reading were it not prevented by damping. (See
Galvanometer, Aperiodic--Damping.)


Dead Earth.
A fault in a telegraph line which consists in the wire being thoroughly
grounded or connected to the earth.


177  STANDARD ELECTRICAL DICTIONARY.


Dead Point of an Alternator.
A two-phase alternator of the ordinary type connected as a motor to
another alternator cannot start itself, as it has dead points where the
relations and polarity of field and armature are such that there is no
torque or turning power.


Dead-Turns.
In the winding of an armature, a given percentage of the turns, it may
be 80 per cent., more or less, is assumed to be active; the other 20 per
cent. or thereabouts, is called dead-turns. This portion represents the
wire on such portions of the armature as comes virtually outside of the
magnetic field. They are termed dead, as not concurring to the
production of electro-motive force.


Dead Wire.
(a) The percentage or portion of wire on a dynamo or motor armature that
does not concur in the production of electromotive force. The
dead-turns, q. v., of a drum armature or the inside wire in a Gramme
ring armature are dead wire.

(b) A disused and abandoned electric conductor, such as a telegraph
wire.

(c) A wire in use, but through which, at the time of speaking, no
current is passing.


Death, Electrical.
Death resulting from electricity discharged through the animal system.
The exact conditions requisite for fatal results have not been
determined. High electro-motive force is absolutely essential; a
changing current, pulsatory or alternating, is most fatal, possibly
because of the high electro-motive force of a portion of each period.
Amperage probably has something to do with it, although the total
quantity in coulombs may be very small. As applied to the execution of
criminals, the victim is seated in a chair and strapped thereto. One
electrode with wet padded surface is placed against his head or some
adjacent part. Another electrode is placed against some of the lower
parts, and a current from an alternating dynamo passed for 15 seconds or
more. The potential difference of the electrodes is given at 1,500 to
2,000 volts, but of course the maximum may be two or three times the
measured amount, owing to the character of the current.


Decalescence.
The converse of recalescence, q. v. When a mass of steel is being heated
as it reaches the temperature of recalescence it suddenly absorbs a
large amount of heat, apparently growing cooler.


Deci.
Prefix originally used in the metric system to signify one-tenth of, now
extended to general scientific units. Thus decimeter means one-tenth of
a meter; decigram, one-tenth of a gram.


Declination, Angle of.
The angle intercepted between the true meridian and the axis of a
magnetic needle at any place. The angle is measured to east or west,
starting from the true meridian as zero.


178   STANDARD ELECTRICAL DICTIONARY.


Declination of the Magnetic Needle.
The deviation of the magnetic needle from the plane of the earth's
meridian. It is also called the variation of the compass. (See Magnetic
Elements.)


Decomposition.
The reduction of a compound substance into its constituents, as in
chemical analysis. The constituents may themselves be compounds or
proximate constituents, or may be elemental or ultimate constituents.


Decomposition, Electrolytic.
The decomposition or separation of a compound liquid into its
constituents by electrolysis. The liquid must be an electrolyte, q. v.,
and the decomposition proceeds subject to the laws of electrolysis, q.
v. See also Electrolytic Analysis.


Decrement.
When a suspension needle which has been disturbed is oscillating the
swings gradually decrease in amplitude if there is any damping, as there
always is. The decrement is the ratio of the amplitude of one
oscillation to the succeeding one. This ratio is the same for any
successive swings.


De-energize.
To cut off its supply of electric energy from an electric motor, or any
device absorbing and worked by electric energy.


Deflagration.
The explosive or violent volatilizing and dissipating of a substance by
heat, violent oxidation and similar means. It may be applied among other
things to the destroying of a conductor by an intense current, or the
volatilization of any material by the electric arc.


Deflecting Field.
The field produced in a galvanometer by the current which is being
tested, and which field deflects the needle, such deflection being the
measure of the current strength.


Deflection.
In magnetism the movement out of the plane of the magnetic meridian of a
magnetic needle, due to disturbance by or attraction towards a mass of
iron or another magnet.


Deflection Method.
The method of electrical measurements in which the deflection of the
index of the measuring instrument is used as the measure of the current
or other element under examination. It is the opposite of and is to be
distinguished from the zero or null method, q. v. In the latter
conditions are established which make the index point to zero and from
the conditions necessary for this the measurement is deduced. The
Wheatstone Bridge, q. v., illustrates a zero method, the sine or the
tangent compass, illustrates a deflection method. The use of deflection
methods involves calibration, q. v., and the commercial measuring
instruments, such as ammeters and volt meters, which are frequently
calibrated galvanometers, are also examples of deflection instruments.


179  STANDARD ELECTRICAL DICTIONARY.


Degeneration, Reaction of.
The diminished sensibility to electro-therapeutic treatment exhibited by
the human system with continuance of the treatment in question. The
general lines of variation are stated in works on the subject.


Deka.
Prefix originally used in the metric system to signify multiplying by
ten, as dekameter, ten meters, dekagram, ten grams; now extended to many
scientific terms.


De la Rive's Floating Battery.
A small galvanic couple, immersed in a little floating cell and
connected through a coil of wire immediately above them. When the
exciting battery solution is placed in the cell the whole, as it floats
in a larger vessel, turns until the coil lies at right angles to the
magnetic needle. Sometimes the two plates are thrust through a cork and
floated thus in a vessel of dilute sulphuric acid.

A magnet acts to attract or repel the coil in obedience to AmpÉre's
Theory, (See Magnetism, Ampere's Theory of.)


Delaurier's Solution.
A solution for batteries of the Bunsen and Grenet type. It is of the
following composition:
     Water,                2,000 parts;
  potassium bichromate,   184 parts;
  sulphuric acid,         428 parts.


Demagnetization.
Removal of magnetism from a paramagnetic substance. It is principally
used for watches which have become magnetized by exposure to the
magnetic field surrounding dynamos or motors.

The general principles of most methods are to rotate the object, as a
watch, in a strong field, and while it is rotating to gradually remove
it from the field, or to gradually reduce the intensity of the field
itself to zero. A conical coil of wire within which the field is
produced in which the watch is placed is sometimes used, the idea being
that the field within such a coil is strongest at its base. Such a coil
supplied by an alternating current is found effectual (J. J. Wright).

If a magnetized watch is made to turn rapidly at the end of a twisted
string and is gradually brought near to and withdrawn from the poles of
a powerful dynamo it may be considerably improved.

A hollow coil of wire connected with a pole changer and dip-battery has
been used. The battery creates a strong field within the coil. The watch
is placed there and the pole changer is worked so as to reverse the
polarity of the field very frequently. By the same action of the pole
changer the plates of the battery are gradually withdrawn from the
solution so as to gradually reduce the magnetic field to zero while
constantly reversing its polarity. (G. M. Hopkins.)

Steel may be demagnetized by jarring when held out of the magnetic
meridian, or by heating to redness.


180   STANDARD ELECTRICAL DICTIONARY.


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

Synonyms--Density of Charge--Surface Density.


Dental Mallet, Electric.
A dentist's instrument for hammering the fillings as inserted into
teeth. It is a little hammer held in a suitable handle, and which is
made to strike a rapid succession of blows by electro-magnetic motor
mechanism.


Depolarization.
(a) The removal of permanent magnetism. (See Demagnetization.)

(b) The prevention of the polarization of a galvanic cell. It is
effected in the Grove battery by the reduction of nitric acid; in the
Bunsen, by the reduction of chromic acid; in the Smee battery,
mechanically, by the platinum coated or rather platinized negative
plate. Other examples will be found under the description of various
cells and batteries. A fluid which depolarizes is termed a depolarizer
or depolarizing fluid or solution. (See Electropoion Fluid.)


Deposit, Electrolytic.
The metal or other substance precipitated by the action of a battery or
other current generator.


Derivation, Point of.
A point where a circuit branches or divides into two or more leads. The
separate branches then receive derived or partial currents.


Desk Push.
A press or push button, with small flush rim, for setting into the
woodwork of a desk.


Detector.
A portable galvanometer, often of simple construction, used for rough or
approximate work.


Detector, Lineman's.
A portable galvanometer with a high and a low resistance actuating coil,
constructed for the use of linemen and telegraph constructors when in
the field, and actually putting up, repairing or testing lines.


Deviation, Quadrantal.
Deviation of the compass in iron or steel ships due to the magnetization
of horizontal beams by the earth's induction. The effect of this
deviation disappears when the ship is in the plane of the electric
meridian, or at right angles thereto; its name is taken from the fact
that a swing of the ship through a quadrant brings the needle from zero
deviation to a maximum and back to zero.


181  STANDARD ELECTRICAL DICTIONARY.


Deviation, Semicircular.
Deviation of the compass in iron or steel ships due to vertical
induction. (See Induction, Vertical.) The effect of this induction
disappears when the ship is in the electric meridian. Its name is
derived from the fact that a swing of the ship through half the circle
brings the needle from zero deviation to a maximum and back to zero.


Dextrotorsal. adj.
Wound in the direction or sense of a right-handed screw; the reverse of
sinistrotorsal, q. v.



Fig. 128. DEXTROTORSAL HELIX.


Diacritical. adj.
(a) The number of ampere turns, q. v., required to bring an iron core to
one half its magnetic saturation, q. v., is termed the diacritical
number.

(b) The diacritical point of magnetic saturation is proposed by Sylvanus
P. Thompson as a term for the coefficient of magnetic saturation which
gives a magnet core one-half its maximum magnetization.


Diagnosis, Electro.
A medical diagnosis of a patient's condition based on the action of
different parts of the body under electric excitement.


Diamagnetic. adj.
Possessing a negative coefficient of magnetic susceptibility; having
permeability inferior to that of air. Such substances placed between the
poles of a magnet are repelled; if in the form of bars, they tend to
turn so as to have their long axis at right angles to the line joining
the poles. The reason is that the lines of force always seek the easiest
path, and these bodies having higher reluctance than air, impede the
lines of force, and hence are as far as possible pushed out of the way.
The above is the simplest explanation of a not well understood set of
phenomena. According to Tyndall, "the diamagnetic force is a polar
force, the polarity of diamagnetic bodies being opposed to that of
paramagnetic ones under the same conditions of excitement." Bismuth is
the most strongly diamagnetic body known; phosphorus, antimony, zinc,
and many others are diamagnetic. (See Paramagnetic.)


182   STANDARD ELECTRICAL DICTIONARY.


Diagometer.
An apparatus for use in chemical analysis for testing the purity of
substances by the time required for a charged surface to be discharged
through them to earth. It is the invention of Rousseau.

An electrometer is charged with a dry pile. One of its terminals is
connected with one surface of the solution or substance to be tested,
and the other with the other surface. The time of discharge gives the
index of the purity of the substance.


Diamagnetic Polarity.
Treating diamagnetism as due to a polar force, the polarity of a
diamagnetic body is the reverse of the polarity of iron or other
paramagnetic bodies. A bar-shaped diamagnetic body in a field of force
tends to place itself at right angles to the lines of force.


Diamagnetism.
(a) The science or study of diamagnetic substances and phenomena.

(b) The magnetic property of a diamagnetic substance.


Diameter of Commutation.
The points on the commutator of a closed circuit ring--or
drum--armature, which the brushes touch, and whence they take the
current, mark the extremities of the diameter of commutation. Were it
not for the lag this would be the diameter at right angles to the line
connecting the centers of the opposite faces of the field. It is always
a little to one side of this position, being displaced in the direction
of rotation. In open circuit armatures the brushes are placed on the
diameter at right angles to this one, and sometimes the term diameter of
commutation is applied to it. All that has been said is on the
supposition that the armature divisions correspond not only in
connection but in position with those of the armature coils. Of course,
the commutator could be twisted so as to bring the diameter of
commutation into any position desired.


Diapason, Electric.
A tuning-fork or diapason kept in vibration by electricity. In general
principle the ends of the fork act as armatures for an electro-magnet,
and in their motion by a mercury cup or other form of contact they make
and break the circuit as they vibrate. Thus the magnet alternately
attracts and releases the leg, in exact harmony with its natural period
of vibration.


Diaphragm.
(a) In telephones and microphones a disc of iron thrown into motion by
sound waves or by electric impulses, according to whether it acts as the
diaphragm of a transmitter or receiver. It is generally a plate of
japanned iron such as used in making ferrotype photographs. (See
Telephone and Microphone.)

(b) A porous diaphragm is often used in electric decomposition cells and
in batteries. The porous cup represents the latter use.

[Transcriber's note: Japanned--covered with heavy black lacquer, like
enamel paint.]


183  STANDARD ELECTRICAL DICTIONARY.


Dielectric.
A non-conductor; a substance, the different parts of which may, after an
electric disturbance, remain, without any process of readjustment, and
for an indefinite period of time, at potentials differing to any extent
(Daniell). There is no perfect dielectric. The term dielectric is
generally only used when an insulator acts to permit induction to take
place through it, like the glass of a Leyden jar.


Dielectric Constant.
The number or coefficient expressing the relative dielectric capacity of
a medium or substance. (See Capacity, Specific Inductive.)


Dielectric, Energy of.
In a condenser, the conducting coatings are merely to conduct the
current all over the surface they cover; the keeping the electricities
separated is the work of the dielectric, and represents potential energy
which appears in the discharge. The amount of energy is proportional to
the charge, and to the potential difference. As any electrified body
implies an opposite electrification somewhere, and a separating
dielectric, the existence of a condenser is always implied.

[Transcriber's note: The energy stored in a capacitor (condenser) is
(Q*Q)/2C = (Q*V)/2 = (C*V*V)/2
The energy is proportional to the voltage SQUARED or the charge SQUARED.]


Dielectric Polarization.
A term due to Faraday. It expresses what he conceived to be the
condition of a dielectric when its opposite faces are oppositely
electrified. The molecules are supposed to be arranged by the
electrification in a series of polar chains, possibly being originally
in themselves seats of opposite polarities, or having such imparted to
them by the electricities. The action is analogous to that of a magnet
pole on a mass of soft iron, or on a pile of iron filings.


Dielectric Strain.
The strain a solid dielectric is subjected to, when its opposite
surfaces are electrified. A Leyden jar dilates under the strain, and
when discharged gives a dull sound. The original condition is not
immediately recovered. Jarring, shaking, etc., assist the recovery from
strain. The cause of the strain is termed Electric Stress. (See Stress,
Electric.) This is identical with the phenomenon of residual charge.
(See Charge, Residual.) Each loss of charge is accompanied with a
proportional return of the dielectric towards its normal condition.


Dielectric Resistance.
The mechanical resistance a body offers to perforation or destruction by
the electric discharge.


Dielectric Strength.
The resistance to the disruptive discharge and depending on its
mechanical resistance largely or entirely. It is expressible in volts
per centimeter thickness. Dry air requires 40,000 volts per centimeter
for a discharge.


184   STANDARD ELECTRICAL DICTIONARY.


Differential Winding Working.
A method of working an electro-magnet intermittently, so as to avoid
sparking. The magnet is wound with two coils. One is connected straight
into the circuit, the other is connected in parallel therewith with a
switch inserted. The coils are so connected that when the switch is
closed the two are in opposition, the current going through them in
opposite senses. Thus one overcomes the effect of the other and the
magnet core shows no magnetism, provided the two coils are of equal
resistance and equal number of convolutions or turns.



Fig. 129. DIFFERENTIAL WINDING WORKING
OF ELECTRO-MAGNETIC APPARATUS.


Diffusion.
A term properly applied to the varying current density found in
conductors of unequal cross sectional area. In electro-therapeutics it
is applied to the distribution of current as it passes through the human
body. Its density per cross-sectional area varies with the area and
with the other factors.


Diffusion Creep.
When electrodes of an active circuit are immersed in a solution of an
electrolyte, a current passes electrolytically if there is a sufficient
potential difference. The current passes through all parts of the
solution, spreading out of the direct prism connecting or defined by the
electrodes. To this portion of the current the above term is applied. If
the electrodes are small enough in proportion to the distance between
them the current transmission or creep outside of the line becomes the
principal conveyor of the current so that the resistance remains the
same for all distances.


Dimensions and Theory of Dimensions.
The expression of the unitary value of a physical quantity in one or
more of the units of length (L), time (T) and mass (M) is termed the
dimensions of such quantity. Thus the dimension or dimensions of a
distance is simply L; of an angle, expressible by dividing the arc by
the radius is L/L; of a velocity, expressible by distance divided by
time--L/T; of acceleration, which is velocity acquired in a unit of
time, and is therefore expressible by velocity divided by time--L/T/T or
L/T2; of momentum, which is the product of mass into velocity--M*L/T; of
kinetic energy taken as the product of mass into the square of
velocity--M*(L2/T2); of potential energy taken as the product of mass
into acceleration into space-M*(L/T2)*L reducing to M*(L2/T2). The
theory is based on three fundamental units and embraces all electric
quantities. The simple units generally taken are the gram, centimeter
and second and the dimensions of the fundamental compound units are
expressed in terms of these three, forming the centimeter-gram-second or
C. G. S. system of units. Unless otherwise expressed or implied the
letters L, M and T, may be taken to indicate centimeter, gram and second
respectively. It is obvious that very complicated expressions of
dimensions may be built up, and that a mathematical expression of
unnamed quantities may be arrived at. Dimensions in their application by
these symbols are subject to the laws of algebra. They were invented by
Fourier and were brought into prominence by J. Clerk Maxwell. Another
excellent definition reads as follows: "By the dimensions of a physical
quantity we mean the quantities and powers of quantities, involved in
the measurement of it." (W. T. A. Emtage.)


185  STANDARD ELECTRICAL DICTIONARY.


Dimmer.
An adjustable choking coil used for regulating the intensity of electric
incandescent lights. Some operate by the introduction and withdrawal of
an iron core as described for the choking coil (see Coil, Choking),
others by a damper of copper, often a copper ring surrounding the coil
and which by moving on or off the coil changes the potential of the
secondary circuit.


Dip of Magnetic Needle.
The inclination of the magnetic needle. (See Elements, Magnetic.)


Dipping.
(a) Acid or other cleaning processes applied by dipping metals in
cleaning or pickling solutions before plating in the electroplater's
bath.

(b) Plating by dipping applies to electroplating without a battery by
simple immersion. Copper is deposited on iron from a solution of copper
sulphate in this way.

Synonym--Simple Immersion.


Dipping Needle.
A magnet mounted in horizontal bearings at its centre of gravity. Placed
in the magnetic meridian it takes the direction of the magnetic lines of
force of the earth at that point. It is acted on by the vertical
component of the earth's magnetism, as it has no freedom of horizontal
movement. (See Magnetic Elements, and Compass, Inclination.)

Directing Magnet.
In a reflecting galvanometer the magnet used for controlling the
magnetic needle by establishing a field. It is mounted on the spindle of
the instrument above the coil and needle.

Synonym--Controlling Magnet.


186   STANDARD ELECTRICAL DICTIONARY.


Direction.
(a) The direction of an electric current is assumed to be from a
positively charged electrode or terminal to a negatively charged one in
the outer circuit. (See Current.)

(b) The direction of magnetic and electro-magnetic lines of force is
assumed to be from north to south pole of a magnet in the outer circuit.
It is sometimes called the positive direction. Their general course is
shown in the cuts diagrammatically. The circles indicate a compass used
in tracing their course. The magnetic needle tends to place itself in
the direction of or tangential to the lines of force passing nearest it.

(c) The direction of electrostatic lines of force is assumed to be out
of a positively charged and to a negatively charged surface.



Fig. 130. DIRECTION OF LINES OF FORCE OF A PERMANENT MAGNET.

Fig. 131, DIRECTION OF LINES OF FORCE OF AN ELECTRO-MAGNET.


187   STANDARD ELECTRICAL DICTIONARY.


Directive Power.
In magnetism the power of maintaining itself in the plane of the
magnetic meridian, possessed by the magnetic needle.


Discharge, Brush.
The static discharge of electricity into or through the air may be of
the brush or spark form. The brush indicates the escape of electricity
in continuous flow; the spark indicates discontinuity. The conditions
necessary to the production of one or the other refer to the nature of
the conductor, and of other conductors in its vicinity and to the
electro-motive force or potential difference; small alterations may
transform one into the other. The brush resembles a luminous core whose
apex touches the conductor. It is accompanied by a slight hissing noise.
Its luminosity is very feeble. The negative conductor gives a smaller
brush than that of the positive conductor and discharges it more
readily. When electricity issues from a conductor, remote from an
oppositely excited one, it gives an absolutely silent discharge, showing
at the point of escape a pale blue luminosity called electric glow, or
if it escapes from points it shows a star-like centre of light. It can
be seen in the dark by placing a point on the excited conductor of a
static-electric machine.

Synonyms--Silent Discharge--Glow Discharge.


Discharge, Conductive.
A discharge of a static charge by conduction through a conductor.


Discharge, Convective.
The discharge of static electricity from an excited conductor through



Earth.
(a) The earth is arbitrarily taken as of zero electrostatic potential.
Surfaces in such condition that their potential is unchanged when
connected to the earth are said to be of zero potential. All other
surfaces are discharged when connected to the earth, whose potential,
for the purposes of man at least, never changes.

(b) As a magnetic field of force the intensity of the earth's field is
about one-half a line of force per square centimeter.

(c) The accidental grounding of a telegraph line is termed an earth, as
a dead, total, partial, or intermittent earth, describing the extent and
character of the trouble.

[Transcriber's note: Fallen power lines can produce voltage gradients on
the earth's surface that make walking in the area dangerous, as in
hundreds of volts per foot. Lightning may be associated with substantial
changes in the static ground potential.]


Earth, Dead.
A fault, when a telegraph or other conductor is fully connected to earth
or grounded at some intermediate point.

Synonyms--Solid Earth--Total Earth.


Earth, Partial.
A fault, when a telegraph or other conductor is imperfectly connected to
earth or grounded at some intermediate point.


Earth Plate.
A plate buried in the earth to receive the ends of telegraph lines or
other circuits to give a ground, q. v. A copper plate is often used. A
connection to a water or gas main gives an excellent ground, far better
than any plate. When the plate oxidizes it is apt to introduce
resistance.


Earth Return.
The grounding of a wire of a circuit at both ends gives the circuit an
earth return.


Earth, Swinging.
A fault, when a telegraph or other conductor makes intermittent
connection with the earth. It is generally attributable to wind action
swinging the wire, whence the name.


Ebonite.
Hard vulcanized India rubber, black in color. Specific resistance in
ohms per cubic centimeter at 46º C. (115º F.): 34E15 (Ayrton); specific
inductive capacity, (air = 1): 2.56 (WÜllner); 2.76 (Schiller); 3.15
(Boltzmann). It is used in electrical apparatus for supporting members
such as pillars, and is an excellent material for frictional generation
of potential. Its black color gives it its name, and is sometimes made a
point of distinction from Vulcanite, q. v.


204   STANDARD ELECTRICAL DICTIONARY.


Economic Coefficient.
The coefficient of electric efficiency. (See Efficiency, Electric.)


Edison Effect.
A continuous discharge resulting in a true current which takes place
between a terminal of an incandescent lamp filament and a plate placed
near it. The lamp must be run at a definitely high voltage to obtain it.


Ediswan.
An abbreviation for Edison-Swan; the trade name of the incandescent lamp
used in Great Britain, and of other incandescent system apparatus.



Fig. 142. GYMNOTUS ELECTRICUS.


Eel, Electric (Gymnotus Electricus).
An eel capable of effecting the discharge of very high potential
electricity, giving painful or dangerous shocks. Its habitat is the
fresh water, in South America. Faraday investigated it and estimated its
shock as equal to that from fifteen Leyden jars, each of 1.66 square
feet of coating. (See Animal Electricity and Ray, Electric.)


Effect, Counter-inductive.
A counter-electro-motive force due to induction, and opposing a current.


Efficiency.
The relation of work done to energy absorbed. A theoretically perfect
machine would have the maximum efficiency in which the two qualities
named would be equal to each other. Expressed by a coefficient, q. v.,
the efficiency in such case would be equal to 1. If a machine produced
but half the work represented by the energy it absorbed, the rest
disappearing in wasteful expenditure, in heating the bearings, in
overcoming the resistance of the air and in other ways, its efficiency
would be expressed by the coefficient 1/2 or .5, or if one hundred was
the basis, by fifty per centum. There are a number of kinds of
efficiencies of an electric generator which are given below.


Efficiency, Commercial.
Practical efficiency of a machine, obtained by dividing the available
output of work or energy of a machine by the energy absorbed by the same
machine. Thus in a dynamo part of the energy is usefully expended in
exciting the field magnet, but this energy is not available for use in
the outer circuit, is not a part of the output, and is not part of the
dividend.

If M represents the energy absorbed, and W the useful or available
energy, the coefficient of commercial efficiency is equal to W/M. M is
made up of available, unavailable and wasted (by Foucault currents,
etc.,) energy. Calling available energy W, unavailable but utilized
energy w, and wasted energy m, the expression for the coefficient of
commercial efficiency becomes

  W / ( W + w + m )
  when M = W + w + m

Synonym--Net efficiency.


205   STANDARD ELECTRICAL DICTIONARY.


Efficiency, Electrical.
In a dynamo or generator the relation of total electric energy produced,
both wasted and useful or available to the useful or available
electrical energy. If we call W the useful electric and w the wasted
electric energy, the coefficient of electrical efficiency is equal to

  W / ( W + w )

Synonyms--Intrinsic Efficiency--Economic Coefficient--Coefficient of
Electrical Efficiency.


Efficiency of Conversion.
In a dynamo or generator the relation of energy absorbed to total
electric energy produced. Part of the electric energy is expended in
producing the field and in other ways. Thus a generator with high
efficiency of conversion may be a very poor one, owing to the
unavailable electric energy which it produces. The coefficient of
Efficiency of Conversion is obtained by dividing the total electric
energy produced by the energy absorbed in working the dynamo. If M
represents the energy absorbed, or work done in driving the dynamo or
generator, W the useful electric, and w the wasted electrical energy,
then the coefficient of efficiency of conversion is equal to

(W + w ) / M

In the quantity M are included besides available (W) and unavailable (w)
electric energy, the totally wasted energy due to Foucault currents,
etc., calling the latter m, the above formula may be given

( W+ w ) / (W + w + m )

This coefficient may refer to the action of a converter, q. v., in the
alternating system. Synonym--Gross Efficiency.


Efficiency of Secondary Battery, Quantity.
The coefficient obtained by dividing the ampere-hours obtainable from a
secondary battery by the ampere hours required to charge it.


Efficiency of Secondary Battery, Real.
The coefficient obtained by dividing the energy obtainable from a
secondary battery by the energy absorbed in charging it. The energy is
conveniently taken in watt-hours and includes the consideration of the
spurious voltage. (See Battery, Secondary.)


206   STANDARD ELECTRICAL DICTIONARY.


Efflorescence.
The appearance of a dry salt upon the walls of a vessel containing a
solution above the normal water-line from evaporation of a liquid. It
appears in battery jars and in battery carbons, in the latter
interfering with the electrical connections, and oxidizing or rusting
them. (See Creeping.)


Effluvium, Electric.
When a gas is made to occupy the position of dielectric between two
oppositely electrified surfaces a peculiar strain or condition of the
dielectric is produced, which promotes chemical change. The condition is
termed electrical effluvium or the silent discharge. By an apparatus
specially constructed to utilize the condition large amounts of ozone
are produced.

Synonym--Silent Discharge.


Elastic Curve.
A crude expression for a curve without projections or sudden
sinuosities; such a curve as can be obtained by bending an elastic strip
of wood.


Electrepeter.
An obsolete name for a key, switch or pole changer of any kind.


Elasticity, Electric.
The phenomenon of the dielectric is described under this term. When a
potential difference is established between two parts of the dielectric,
a flow of electricity displacement current starts through the
dielectric, which current is due to the electric stress, but is
instantly arrested by what has been termed the electric elasticity of
the dielectric. This is expressed by
  ( electric stress ) / ( electric strain )
and in any substance is inversely proportional to the specific inductive
capacity.


Electricity.
It is impossible in the existing state of human knowledge to give a
satisfactory definition of electricity. The views of various authorities
are given here to afford a basis for arriving at the general consensus
of electricians.

We have as yet no conception of electricity apart from the electrified
body; we have no experience of its independent existence. (J. E. H.
Gordon.)

What is Electricity? We do not know, and for practical purposes it is
not necessary that we should know. (Sydney F. Walker.)

Electricity … is one of those hidden and mysterious powers of nature
which has thus become known to us through the medium of effects.
(Weale's Dictionary of Terms.)

This word Electricity is used to express more particularly the cause,
which even today remains unknown, of the phenomena that we are about to
explain. (AmÉdÉe Guillemin.)

207  STANDARD ELECTRICAL DICTIONARY.

Electricity is a powerful physical agent which manifests itself mainly
by attractions and repulsions, but also by luminous and heating effects,
by violent commotions, by chemical decompositions, and many other
phenomena. Unlike gravity, it is not inherent in bodies, but it is
evoked in them by a variety of causes … (Ganot's Physics.)

Electricity and magnetism are not forms of energy; neither are they
forms of matter. They may, perhaps, be provisionally defined as
properties or conditions of matter; but whether this matter be the
ordinary matter, or whether it be, on the other hand, that
all-pervading ether by which ordinary matter is surrounded, is a question
which has been under discussion, and which now may be fairly held to be
settled in favor of the latter view. (Daniell's Physics.)

The name used in connection with an extensive and important class of
phenomena, and usually denoting the unknown cause of the phenomena or
the science that treats of them. (Imperial Dictionary.)

Electricity. . . is the imponderable physical agent, cause, force or the
molecular movement, by which, under certain conditions, certain
phenomena, chiefly those of attraction and repulsion, . . . are
produced. (John Angell.)

It has been suggested that if anything can rightly be called
"electricity," this must be the ether itself; and that all electrical
and magnetic phenomena are simply due to changes, strains and motions in
the ether. Perhaps negative electrification. . .means an excess of
ether, and positive electrification a defect of ether, as compared with
the normal density. (W. Larden.)

Electricity is the name given to the supposed agent producing the
described condition (i. e. electrification) of bodies. (Fleeming
Jenkin.)

There are certain bodies which, when warm and dry, acquire by friction,
the property of attracting feathers, filaments of silk or indeed any
light body towards them. This property is called Electricity, and bodies
which possess it are said to be electrified. (Linnaeus Cumming.)

What electricity is it is impossible to say, but for the present it is
convenient to look upon it as a kind of invisible something which
pervades all bodies. (W. Perren Maycock.)

What is electricity? No one knows. It seems to be one manifestation of
the energy which fills the universe and which appears in a variety of
other forms, such as heat, light, magnetism, chemical affinity,
mechanical motion, etc. (Park Benjamin.)


208   STANDARD ELECTRICAL DICTIONARY.


The theory of electricity adopted throughout these lessons is, that
electricity, whatever its true nature, is one, not two; that this
Electricity, whatever it may prove to be, is not matter, and is not
energy; that it resembles both matter and energy in one respect,
however, in that it can neither be created nor destroyed. (Sylvanus P.
Thomson.)

In Physics a name denoting the cause of an important class of phenomena
of attraction and repulsion, chemical decomposition, etc., or,
collectively, these phenomena themselves. (Century Dictionary.)

A power in nature, often styled the electric fluid, exhibiting itself,
when in disturbed equilibrium or in activity, by a circuit movement, the
fact of direction in which involves polarity, or opposition of
properties in opposite directions; also, by attraction for many
substances, by a law involving attraction between substances of unlike
polarity, and repulsion between those of like; by exhibiting accumulated
polar tension when the circuit is broken; and by producing heat, light,
concussion, and often chemical changes when the circuit passes between
the poles, or through any imperfectly conducting substance or space. It
is evolved in any disturbance of molecular equilibrium, whether from a
chemical, physical, or mechanical cause. (Webster's Dictionary.)

In point of fact electricity is not a fluid at all, and only in a few of
its attributes is it at all comparable to a fluid. Let us rather
consider electricity to be a condition into which material substances
are thrown. . .(Slingo & Brooker.)

[Transcriber's note: 2008 Dictionary: Phenomena arising from the
behavior of electrons and protons caused by the attraction of particles
with opposite charges and the repulsion of particles with the same
charge.]


Electricity, Cal.
The electricity produced in the secondary of a transformer by changes of
temperature in the core. This is in addition to the regularly induced
current.

Synonym--Acheson Effect.


Electrics.
Substances developing electrification by rubbing or friction; as
Gilbert, the originator of the term, applied it, it would indicate
dielectrics. He did not know that, if insulated, any substance was one
of his "electrics." A piece of copper held by a glass handle becomes
electrified by friction.


Electrification.
The receiving or imparting an electric charge to a surface; a term
usually applied to electrostatic phenomena.


Electrization.
A term in electro-therapeutics; the subjection of the human system to
electric treatment for curative, tonic or diagnostic purposes.


Electro-biology.
The science of electricity in its relation to the living organism,
whether as electricity is developed by the organism, or as it affects
the same when applied from an external source.


209  STANDARD ELECTRICAL DICTIONARY.


Electro-capillarity.
The relations between surface tension, the potential difference and the
electrostatic capacity of fluids in contact. Although nominally in
contact such surfaces are separated by about one-twenty-millionth of a
centimeter (1/50000000 inch) ; thus a globule of mercury and water in
which it is immersed constitute an electrostatic accumulator of definite
electrostatic capacity. Again the mercury and water being in electric
connection differ in potential by contact (see Contact Theory). A
definite surface tension is also established. Any change in one of these
factors changes the other also. A current passed through the contact
surfaces will change the surface tension and hence the shape of the
mercury globule. Shaking the globule will change its shape and capacity
and produce a current. Heating will do the same. (See Electrometer,
Capillary; and Telephone, Capillary.) Mercury and water are named as
liquids in which the phenomena are most conveniently observed. They are
observable in other parallel cases.


Electro-chemical Equivalent.
The quantity of an element or compound liberated from or brought into
combination, electrolytically, by one coulomb of electricity. The
electro-chemical equivalent of hydrogen is found by experiment to be
.0000105 gram. That of any other substance is found by multiplying this
weight by its chemical equivalent referred to hydrogen, which is its
atomic or molecular weight divided by its valency. Thus the atomic
weight of oxygen is 16, its valency is 2, its equivalent is 16/2 = 8;
its electro-chemical equivalent is equal to .0000105 X 8 = .000840 gram.


Electro-chemical Series.
An arrangement of the elements in the order of their relative electrical
affinities so that each element is electro-negative to all the elements
following it, and electro-positive to the elements preceding it. The
usual series begins with oxygen as the most electro-negative and ends
with potassium as the most electro-positive element. There is, of
course, no reason why other series of compound radicals, such as
sulphion (SO4), etc., should not also be constructed. For each liquid
acting on substances a separate series of the substances acted on may be
constructed. Thus for dilute sulphuric acid the series beginning with
the negatively charged or most attacked one is zinc, amalgamated or
pure, cadmium, iron, tin, lead, aluminum, nickel, antimony, bismuth,
copper, silver, platinum. In other liquids the series is altogether
different.


Electro--chemistry.
The branch of electricity or of chemistry treating of the relations
between electric and chemical force in different compounds and
reactions. (See Electrolysis--Electrochemical series--Electro-chemical
Equivalent .)


210   STANDARD ELECTRICAL DICTIONARY.


Electro-culture.
The application of electricity to the cultivation of plants. In one
system wires are stretched or carried across the bed under the surface,
and some are connected to one pole and others to the other pole of a
galvanic battery of two or more elements. In some experiments improved
results have thus been obtained.

Another branch refers to the action of the electric arc light on
vegetation. This has an effect on vegetation varying in results.


Electrode.
(a) The terminal of an open electric circuit.

(b) The terminals of the metallic or solid conductors of an electric
circuit, immersed in an electrolytic solution.

(c) The terminals between which a voltaic arc is formed, always in
practice made of carbon, are termed electrodes.

(d) In electro-therapeutics many different electrodes are used whose
names are generally descriptive of their shape, character, or uses to
which they are to be applied. Such are aural electrodes for the ears,
and many others.

(e) The plates of a voltaic battery.


Electrode, Indifferent.
A term in electro-therapeutics. An electrode to which no therapeutic
action is attributed but which merely provides a second contact with the
body to complete the circuit through the same. The other electrode is
termed the therapeutic electrode.


Electrodes, Erb's Standards of.
Proposed standard sizes for medical electrodes as follows:
  Name.          Diameter.
  Fine     Electrode,   1/2  centimeter   .2      inch
  Small       "         2       "         .8        "
  Medium      "       7.5       "        3.0        "
  Large       "       6X2       "        2.4 X .8   "
  Very large  "      16x8       "        6.4 x 3.2  "


Electrodes, Non-polarizable.
In electro-therapeutics electrodes whose contact surface is virtually
porous clay saturated with zinc chloride solution. The series terminate
in amalgamated zinc ends, enclosed each in a glass tube, and closed with
clay. Contact of metal with the tissues is thus avoided.


Electrode, Therapeutic.
A term in electro-therapeutics. An electrode applied to the body for the
purpose of inducing therapeutic action, or for giving the basis for an
electric diagnosis of the case. The other electrode is applied to
complete the circuit only; it is termed the indifferent electrode.


Electro-diagnosis.
The study of the condition of a patient by the reactions which occur at
the terminals or kathode and anode of an electric circuit applied to the
person. The reactions are divided into kathodic and anodic reactions.


211   STANDARD ELECTRICAL DICTIONARY.


Electro-dynamic. adj.
The opposite of electrostatic; a qualification of phenomena due to
current electricity.

Synonym--Electro-kinetic.


Electro-dynamic Attraction and Repulsion.
The mutual attraction and repulsion exercised by currents of electricity
upon each other. The theory of the cause is based upon stress of the
luminiferous ether and upon the reaction of lines of force upon each
other. For a resumÉ of the theory see Induction, Electro-magnetic.


Electro-dynamics.
The laws of electricity in a state of motion; the inter-reaction of
electric currents. It is distinguished from electro-magnetic induction
as the latter refers to the production of currents by induction. The
general laws of electro-dynamics are stated under Induction,
Electro-magnetic, q. v.

Synonym--Electro-kinetics.



Fig. 143. DIAGRAM OF CONNECTIONS OF
SIEMENS' ELECTRO-DYNAMOMETER.


212   STANDARD ELECTRICAL DICTIONARY.


Electro-dynamometer, Siemens'.
An apparatus for measuring currents by the reaction between two coils,
one fixed and one movable, through which the current to be measured
passes. It is one of the oldest commercial ammeters or current
measurers. It comprises a fixed coil of a number of convolutions and a
movable coil often of only one convolution surrounding the other. The
movable coil is suspended by a filament or thread from a spiral spring.
The spring is the controlling factor. Connection is established through
mercury cups so as to bring the two coils in series. In use the spring
and filament are adjusted by turning a milled head to which they are
connected until the coils are at right angles. Then the current is
turned on and deflects the movable coil. The milled head is turned until
the deflection is overcome. The angle through which the head is turned
is proportional to the square of the current. The movable coil must in
its position at right angles to the fixed one lie at right angles to the
magnetic meridian.

Thus in the diagram, Fig. 143 A B C D is the fixed coil; E F G H is the
movable coil; S is the spiral spring attached at K to the movable coil.
The arrows show the course of the current as it goes through the coils.


Electrolier.
A fixture for supporting electric lamps; the analogue in electric
lighting of the gasolier or gas chandelier. Often both are combined, the
same fixture being piped and carrying gas burners, as well as being
wired and carrying electric lamps.


Electrolysis.
The separation of a chemical compound into its constituent parts or
elements by the action of the electric current. The compound may be
decomposed into its elements, as water into hydrogen and oxygen, or into
constituent radicals, as sodium sulphate into sodium and sulphion, which
by secondary reactions at once give sodium hydrate and sulphuric acid.
The decomposition proceeds subject to the laws of electrolysis. (See
Electrolysis, Laws of.) For decomposition to be produced there is for
each compound a minimum electro-motive force or potential difference
required. The current passes through the electrolyte or substance
undergoing decomposition entirely by Electrolytic Conduction, q. v. in
accordance with GrothÜss' Hypothesis, q. v. The electrolyte therefore
must be susceptible of diffusion and must be a fluid.

The general theory holds that under the influence of a potential
difference between electrodes immersed in an electrolyte, the molecules
touching the electrodes are polarized, in the opposite sense for each
electrode. If the potential difference is sufficient the molecules will
give up one of their binary constituents to the electrode, and the other
constituent will decompose the adjoining molecule, and that one being
separated into the same two constituents will decompose its neighbor,
and so on through the mass until the other electrode is reached. This
one separates definitely the second binary constituent from the
molecules touching it.


213   STANDARD ELECTRICAL DICTIONARY.


Thus there is an exact balance preserved. Just as many molecules are
decomposed at one electrode as at the other, and the exact chain of
decomposition runs through the mass. Each compound electrolyzed develops
a binary or two-fold composition, and gives up one constituent to one
electrode and the other to the other.



Fig. 144. ACTION OF MOLECULES IN A SOLUTION
BEFORE AND DURING ELECTROLYSIS.


The cut shows the assumed polarization of an electrolyte. The upper row
shows the molecules in irregular order before any potential difference
has been produced, in other words, before the circuit is closed. The
next row shows the first effects of closing the circuit, and also
indicates the polarization of the mass, when the potential difference is
insufficient for decomposition. The third row indicates the
decomposition of a chain of molecules, one constituent separating at
each pole.


214   STANDARD ELECTRICAL DICTIONARY.


Electrolysis, Laws of.
The following are the principal laws, originally discovered by
Faraday, and sometimes called Faraday's Laws of Electrolysis:

1. Electrolysis cannot take place unless the electrolyte is a conductor.
Conductor here means an electrolytic conductor, one that conducts by its
own molecules traveling, and being decomposed. (See GrothÜss'
Hypothesis.)

II. The energy of the electrolytic action of the current is the same
wherever exercised in different parts of the circuit.

III. The same quantity of electricity--that is the same current for the
same period----- decomposes chemically equivalent quantities of the
bodies it decomposes, or the weights of elements separated in
electrolytes by the same quantity of electricity (in coulombs or some
equivalent unit) are to each other as their chemical equivalent.

IV. The quantity of a body decomposed in a given time is proportional to
the strength of the current.

To these may be added the following:

V. A definite and fixed electro-motive force is required for the
decomposition of each compound, greater for some and less for others.
Without sufficient electro-motive force expended on the molecule no
decomposition will take place. (See Current, Convective.)


Electrolyte.
A body susceptible of decomposition by the electric current, and capable
of electrolytic conduction. It must be a fluid body and therefore
capable of diffusion, and composite in composition. An elemental body
cannot be an electrolyte.


Electrolytic Analysis.
Chemical analysis by electrolysis. The quantitative separation of a
number of metals can be very effectively executed. Thus, suppose that a
solution of copper sulphate was to be analyzed. A measured portion of
the solution would be introduced into a weighed platinum vessel. The
vessel would be connected to the zinc plate terminal of a battery. From
the other terminal of the battery a wire would be brought and would
terminate in a plate of platinum. This would be immersed in the solution
in the vessel. As the current would pass the copper sulphate would be
decomposed and eventually all the copper would be deposited in a firm
coating on the platinum. The next operations would be to wash the metal
with distilled water, and eventually with alcohol, to dry and to weigh
the dish with the adherent copper. On subtracting the weight of the dish
alone from the weight of the dish and copper, the weight of the metallic
copper in the solution would be obtained.

In similar ways many other determinations are effected. The processes of
analysis include solution of the ores or other substances to be analyzed
and their conversion into proper form for electrolysis. Copper as just
described can be precipitated from the solution of its sulphate. For
iron and many other metals solutions of their double alkaline oxalates
are especially available forms for analysis.

The entire subject has been worked out in considerable detail by
Classen, to whose works reference should be made

Electrometer, Capillary.
An electrometer for measuring potential difference by capillary action,
which latter is affected by electrostatic excitement. A tube A contains
mercury; its end drawn out to a fine aperture dips into a vessel B which
contains dilute sulphuric acid with mercury under it, as shown. Wires
running from the binding-posts a and b connect one with the mercury in
A, the other with that in B. The upper end of the tube A connects with a
thick rubber mercury reservoir T, and manometer H. The surface tension
of the mercury-acid film at the lower end of the tube A keeps all in
equilibrium. If now a potential difference is established between a and
b, as by connecting a battery thereto, the surface tension is increased
and the mercury rises in the tube B. By screwing down the compressing
clamp E, the mercury is brought back to its original position. The
microscope M is used to determine this position with accuracy. The
change in reading of the manometer gives the relation of change of
surface tension and therefore of potential. Each electrometer needs
special graduation or calibration, but is exceedingly sensitive and
accurate. It cannot be used for greater potential differences than .6
volt, but can measure .0006 volt. Its electrostatic capacity is so small
that it can indicate rapid changes. Another form indicates potential
difference by the movement of a drop of sulphuric acid in a horizontal
glass tube, otherwise filled with mercury, and whose ends lead into two
mercury cups or reservoirs. The pair of electrodes to be tested are
connected to the mercury vessels. The drop moves towards the negative
pole, and its movement for small potential differences (less than one
volt) is proportional to the electro-motive force or potential
difference.


226   STANDARD ELECTRICAL DICTIONARY.


Electrometer Gauge.
An absolute electrometer (see Electrometer, Absolute) forming an
attachment to a Thomson quadrant electrometer. It is used to test the
potential of the flat needle connected with the inner surface of the
Leyden jar condenser of the apparatus. This it does by measuring the
attraction between itself and an attracting disc, the latter connected
by a conductor with the interior of the jar.


Electrometer, Lane's.
A Leyden jar with mounted discharger, so that when charged to a certain
point it discharges itself. It is connected with one coating of any jar
whose charge is to be measured, which jar is then charged by the other
coating. As the jar under trial becomes charged to a certain point the
electrometer jar discharges itself, and the number of discharges is the
measure of the charge of the other jar. It is really a unit jar, q. v.



Fig. 156. THOMSON'S QUADRANT ELECTROMETER.



Fig. 157. HENLEY'S QUADRANT ELECTROSCOPE.


227  STANDARD ELECTRICAL DICTIONARY.


Electrometer, Quadrant.
(a) Sir William Thomson's electrometer, a simple form of which is shown
in the cut, consists of four quadrants of metal placed horizontally;
above these a broad flat aluminum needle hangs by a very fine wire,
acting as torsional suspension. The quadrants are insulated from each
other, but the opposite ones connect with each other by wires. The
apparatus is adjusted so that, when the quadrants are in an unexcited
condition the needle is at rest over one of the diametrical divisions
between quadrants. The needle by its suspension wire is in communication
with the interior of a Leyden jar which is charged. The whole is covered
with a glass shade, and the air within is kept dry by a dish of
concentrated sulphuric acid so that the jar retains its charge for a
long time and keeps the needle at approximately a constant potential. If
now two pairs of quadrants are excited with opposite electricities, as
when connected with the opposite poles of an insulated galvanic cell,
the needle is repelled by one pair and attracted by the other, and
therefore rotates through an arc of greater or less extent. A small
concave mirror is attached above the needle and its image is reflected
on a graduated screen. This makes the smallest movement visible.
Sometimes the quadrants are double, forming almost a complete box,
within which the needle moves.

(b) Henley's quadrant electrometer is for use on the prime conductor of
an electric machine, for roughly indicating the relative potential
thereof. It consists of a wooden standard attached perpendicularly to
the conductor. Near one end is attached a semi-circular or quadrant arc
of a circle graduated into degrees or angular divisions. An index,
consisting of a straw with a pith-bell attached to its end hangs from
the center of curvature of the arc. When the prime conductor is charged
the index moves up over the scale and its extent of motion indicates the
potential relatively.

When the "quadrant electrometer" is spoken of it may always be assumed
that Sir William Thomson's instrument is alluded to. Henley's instrument
is properly termed a quadrant electroscope. (See Electroscope.)


Electro-motive Force.
The cause which produces currents of electricity. In general it can be
expressed in difference of potentials, although the term electro-motive
force should be restricted to potential difference causing a current. It
is often a sustained charging of the generator terminals whence the
current is taken. Its dimensions are

(work done/the quantity of electricity involved),

or ( M * (L^2) /(T^2 ) ) / ((M^.5) * (L^.5)) = ( (M^.5) * (L^1.5) ) /(T^2)

The practical unit of electro-motive force is the volt, q. v. It is
often expressed in abbreviated form, as E. M. D. P., or simply as D. P.,
i. e., potential difference.

Electro-motive force and potential difference are in many cases
virtually identical, and distinctions drawn between them vary with
different authors. If we consider a closed electric circuit carrying a
current, a definite electro-motive force determined by Ohm's law from
the resistance and current obtains in it. But if we attempt to define
potential difference as proper to the circuit we may quite fail.
Potential difference in a circuit is the difference in potential between
defined points of such circuit. But no points in a closed circuit can be
found which differ in potential by an amount equal to the entire
electro-motive force of the circuit. Potential difference is properly
the measure of electro-motive force expended on the portion of a circuit
between any given points. Electro-motive force of an entire circuit, as
it is measured, as it were, between two consecutive points but around
the long portion of the circuit, is not conceivable as merely potential
difference. Taking the circle divided in to degrees as an analogy, the
electro-motive force of the entire circuit might be expressed as 360º,
which are the degrees intervening between two consecutive points,
measured the long way around the circle. But the potential difference
between the same two points would be only 1º, for it would be measured
by the nearest path.

[Transcriber's notes: If 360º is the "long" way, 0º is the "short". A
formal restatement of the above definition of EMF: "If a charge Q passes
through a device and gains energy U, the net EMF for that device is the
energy gained per unit charge, or U/Q. The unit of EMF is a volt, or
newton-meter per coulomb."]


228   STANDARD ELECTRICAL DICTIONARY.


Electro-motive Force, Counter.
A current going through a circuit often has not only true or ohmic
resistance to overcome, but meets an opposing E. M. F. This is termed
counter-electro-motive force. It is often treated in calculations as
resistance, and is termed spurious resistance. It may be a part of the
impedance of a circuit.

In a primary battery hydrogen accumulating on the negative plate
develops counter E. M. F. In the voltaic arc the differential heating of
the two carbons does the same. The storage battery is changed by a
current passing in the opposite direction to its own natural current;
the polarity of such a battery is counter E. M. F.


Electro-motive Force, Unit.
Unit electro-motive force is that which is created in a conductor moving
through a magnetic field at such a rate as to cut one unit line of force
per second. It is that which must be maintained in a circuit of unit
resistance to maintain a current of unit quantity therein. It is that
which must be maintained between the ends of a conductor in order that
unit current may do unit work in a second.


Electro-motive Intensity.
The force acting upon a unit charge of electricity. The mean force is
equal to the difference of potential between two points within the field
situated one centimeter apart, such distance being measured along the
lines of force. The term is due to J. Clerk Maxwell.


Electro-motive Series.
Arrangement of the metals and carbon in series with the most
electro-positive at one end, and electronegative at the other end. The
following are examples for different exciting liquids:

Dilute Sulphuric   Dilute Hydrochloric   Caustic   Potassium
Acid               Acid.                 Potash.   Sulphide.

Zinc               Zinc                  Zinc      Zinc
Cadmium            Cadmium               Tin       Copper
Tin                Tin                   Cadmium   Cadmium
Lead               Lead                  Antimony  Tin
Iron               Iron                  Lead      Silver
Nickel             Copper                Bismuth   Antimony
Bismuth            Bismuth               Iron      Lead
Antimony           Nickel                Copper    Bismuth
Copper             Silver                Nickel    Nickel
Silver             Antimony              Silver    Iron
Gold
Platinum
Carbon

In each series the upper metal is the positive, dissolved or attacked
element.


229  STANDARD ELECTRICAL DICTIONARY.


Electro-motograph.
An invention of Thomas A. Edison. A cylinder of chalk, moistened with
solution of caustic soda, is mounted so as to be rotated by a handle. A
diaphragm has an arm connected to its center. This arm is pressed
against the surface of the cylinder by a spring. When the cylinder is
rotated, a constant tension is exerted on the diaphragm. If a current is
passed through the junction of arm and cylinder the electrolytic action
alters the friction so as to change the stress upon the diaphragm.

If the current producing this effect is of the type produced by the
human voice through a microphone the successive variations in strain
upon the diaphragm will cause it to emit articulate sounds. These are
produced directly by the movement of the cylinder, the electrolytic
action being rather the regulating portion of the operation. Hence very
loud sounds can be produced by it. This has given it the name of the
loud- speaking telephone.

The same principle may be applied in other ways. But the practical
application of the motograph is in the telephone described.



Fig. 158. ELECTRO-MOTOGRAPH TELEPHONE


Electro-motor.
This term is sometimes applied to a current generator, such as a voltaic
battery.


Electro-muscular Excitation.
A term in medical electricity indicating the excitation of muscle as the
effect of electric currents of any kind.


Electro-negative. adj.
Appertaining to negative electrification; thus of the elements oxygen is
the most electro-negative, because if separated by electrolytic action
from any combination, it will be charged with negative electricity.


230   STANDARD ELECTRICAL DICTIONARY.


Electro-optics.
The branch of natural science treating of the relations between light
and electricity. Both are supposed to be phenomena of or due to the
luminiferous ether. To it may be referred the following:

(a) Electro-magnetic Stress and Magnetic Rotary Polarization;

(b) Dielectric Strain; all of which may be referred to in this book;

(c) Change in the resistance of a conductor by changes in light to which
it is exposed (see Selenium);

(d) The relation of the index of refraction of a dielectric to the
dielectric constant (see Electro-magnetic Theory of Light);

(e) The identity (approximate) of the velocity of light in centimeters
and the relative values of the electrostatic and electro-magnet units
of intensity, the latter being 30,000,000,000 times greater than the
former, while the velocity of light is 30,000,000,000 centimeters per
second.


Electrophoric Action.
The action of an electrophorous; utilized in influence machines. (See
Electrophorous.)



Fig. 159. ELECTROPHOROUS.


Electrophorous.
An apparatus for the production of electric charges of high potential by
electrostatic induction, q. v. It consists of a disc of insulating
material B, such as resin or gutta percha, which is held in a shallow
metal-lined box or form. The disc may be half an inch thick and a foot
or more in diameter, or may be much smaller and thinner. A metal disc A,
smaller in diameter is provided with an insulating handle which may be
of glass, or simply silk suspension strings. To use it the disc B is
excited by friction with a cat-skin or other suitable substance. The
metallic disc is then placed on the cake of resin exactly in its centre,
so that the latter disc or cake projects on all sides. Owing to
roughness there is little real electric contact between the metal and
dielectric. On touching the metal disc a quantity of negative
electricity escapes to the earth. On raising it from the cake it comes
off excited positively, and gives a spark and is discharged. It can be
replaced, touched, removed and another spark can be taken from it, and
so on as long as the cake stays charged.

The successive discharges represent electrical energy expended. This is
derived from the muscular energy expended by the operator in separating
the two discs when oppositely excited. As generally used it is therefore
an apparatus for converting muscular or mechanical energy into electric
energy.


231   STANDARD ELECTRICAL DICTIONARY.


Electro-physiology.
The science of the electric phenomena of the animal system. It may also
be extended to include plants. The great discovery of Galvani with the
frog's body fell into this branch of science. The electric fishes,
gymnotus, etc., present intense phenomena in the same.


Electroplating.
The deposition by electrolysis of a coating of metal upon a conducting
surface. The simplest system makes the object to be plated the negative
electrode or plate in a galvanic couple. Thus a spoon or other object
may be connected by a wire to a plate of zinc. A porous cup is placed
inside a battery jar. The spoon is placed in the porous cup and the zinc
outside it. A solution of copper sulphate is placed in the porous cup,
and water with a little sodium or zinc sulphate dissolved in it,
outside. A current starts through the couple, and copper is deposited on
the spoon.

A less primitive way is to use a separate battery as the source of
current; to connect to the positive plate by a wire the object to be
plated, and a plate of copper, silver, nickel or other metal to the
other pole of the battery. On immersing both object and plate (anode) in
a bath of proper solution the object will become plated.

In general the anode is of the same material as the metal to be
deposited, and dissolving keeps up the strength of the bath. There are a
great many points of technicality involved which cannot be given here.
The surface of the immersed object must be conductive. If not a fine
wire network stretched over it will gradually fill up in the bath and
give a matrix. More generally the surface is made conductive by being
brushed over with plumbago. This may be followed by a dusting of iron
dust, followed by immersion in solution ot copper sulphate. This has the
effect of depositing metallic copper over the surface as a starter for
the final coat.

Attention must be paid to the perfect cleanliness of the objects, to the
condition of the bath, purity of anodes and current density.

Voltaic batteries are largely used for the current as well as special
low resistance dynamos. Thermo-electric batteries are also used to some
extent but not generally.


Electro-pneumatic Signals.
Signals, such as railroad signals or semaphores, moved by compressed
air, which is controlled by valves operated by electricity. The House
telegraph, which was worked by air controlled by electricity, might come
under this term, but it is always understood as applied to railroad
signals, or their equivalent.


232   STANDARD ELECTRICAL DICTIONARY.


Electropoion Fluid.
An acid depolarizing solution for use in zinc-carbon couples, such as
the Grenet battery. The following are formulae for its preparation:

(a) Dissolve one pound of potassium bichromate in ten pounds of water,
to which two and one-half pounds of concentrated sulphuric acid have
been gradually added. The better way is to use powdered potassium
bichromate, add it to the water first, and then gradually add the
sulphuric acid with constant stirring.

(b) To three pints of water add five fluid ounces of concentrated
sulphuric acid; add six ounces pulverized potassium bichromate.

(c) Mix one gallon concentrated sulphuric acid and three gallons of
water. In a separate vessel dissolve six pounds potassium bichromate in
two gallons of boiling water. Mix the two.

The last is the best formula. Always use electropoion fluid cold. (See
TrouvÉ's Solution--Poggendorff's Solution--Kakogey's Solution--
Tissandrier's Solution--Chutaux's Solution.)


Electro-positive. adj.
Appertaining to positive electrification; thus potassium is the most
electro-positive of the elements. (See Electro-negative.)


Electro-puncture.
The introduction into the system of a platinum point or needle,
insulated with vulcanite, except near its point, and connected as the
anode of a galvanic battery. The kathode is a metal one, covered with a
wet sponge and applied on the surface near the place of puncture. It is
used for treatment of aneurisms or diseased growths, and also for
removal of hair by electrolysis. (See Hair, Removal of by Electrolysis.)

Synonym--Galvano-puncture.


Electro-receptive. adj.
A term applied to any device or apparatus designed to receive and absorb
electric energy. A motor is an example of an electro-receptive
mechanism.


Electroscope.
An apparatus for indicating the presence of an electric charge, and also
for determining the sign, or whether the charge is positive or negative.
The simplest form consists of a thread doubled at its centre and hung
therefrom. On being charged, or on being connected to a charged body the
threads diverge. A pair of pith balls may be suspended in a similar way,
or a couple of strips of gold leaf within a flask (the gold leaf
electroscope). To use an electroscope to determine the sign of the
charge it is first slightly charged. The body to be tested is then
applied to the point of suspension, or other charging point. If at once
further repelled the charge of the body is of the same sign as the
slight charge first imparted to the electroscope leaves; the leaves as
they become more excited will at once diverge more. If of different sign
they will at first approach as their charge is neutralized and will
afterwards diverge.

The gold-leaf electroscope is generally enclosed in a glass bell jar or
flask. Sometimes a pair of posts rise, one on each side, to supply
points of induction from the earth to intensify the action. (See
Electrometer, Quadrant--Electroscope, Gold leaf, and others.)


233  STANDARD ELECTRICAL DICTIONARY.


Electroscope, Bennett's.
A gold-leaf electroscope, the suspended leaves of which are contained in
a glass shade or vessel of dry air. On the inside of the glass shade are
two strips of gold leaf, which rise from the lower edge a short
distance, being pasted to the glass, and connected to the ground. These
act by induction to increase the sensitiveness of the instruments.


Electroscope, Bohenberger's.
A condensing electroscope (see Electroscope, Condensing) with a single
strip of gold leaf suspended within the glass bell. This is at an equal
distance from the opposite poles of two dry piles (see Zamboni's Dry
Pile) standing on end, one on each side of it. As soon as the leaf is
excited it moves toward one and away from the other pile, and the sign
of its electrification is shown by the direction of its motion.


Electroscope, Condensing.
A gold leaf electroscope, the glass bell of which is surmounted by an
electrophorous or static condenser, to the lower plate of which the
leaves of gold are suspended or connected.

In use the object to be tested is touched to the lower plate, and the
upper plate at the same time is touched by the finger. The plates are
now separated. This reduces the capacity of the lower plate greatly and
its charge acquires sufficient potential to affect the leaves, although
the simple touching may not have affected them at all.


Electroscope, Gold Leaf.
An electroscope consisting of two leaves of gold leaf hung in contact
with each other from the end of a conductor. When excited they diverge.
The leaves are enclosed in a glass vessel.



Fig. 160. GOLD LEAF ELECTROSCOPE.


234   STANDARD ELECTRICAL DICTIONARY.


Electroscope, Pith Ball.
Two pith balls suspended at opposite ends of a silk thread doubled in
the middle. When charged with like electricity they repel each other.
The extent of their repulsion indicates the potential of their charge.


Electrostatic Attraction and Repulsion.
The attraction and repulsion of electrostatically charged bodies for
each other, shown when charged with electricity. If charged with
electricity of the same sign they repel each other. If with opposite
they attract each other. The classic attraction and subsequent repulsion
of bits of straw and chaff by the excited piece of amber is a case of
electrostatic attraction and repulsion. (See Electricity,
Static--Electrostatics--Coulomb's Laws of Electrostatic Attraction and
Repulsion.)


Electrostatic Induction, Coefficient of.
The coefficient expressing the ratio of the charge or change of charge
developed in one body to the potential of the inducing body.


Electrostatic Lines of Force.
Lines of force assumed to exist in an electrostatic field of force, and
to constitute the same. In general they correspond in action and
attributes with elcctro-magnetic lines of force. They involve in almost
all cases either a continuous circuit, or a termination at both ends in
oppositely charged surfaces.



Fig. 161. ELECTROSTATIC LINES OF FORCE
BETWEEN NEAR SURFACES.



Fig. 162. ELECTROSTATIC LINKS OF FORCE
BETWEEN DISTANT SURFACES.


235   STANDARD ELECTRICAL DICTIONARY.


The cut, Fig. 161, shows the general course taken by lines of force
between two excited surfaces when near together. Here most of them are
straight lines reaching straight across from surface to surface, while a
few of them arch across from near the edges, tending to spread. If the
bodies are drawn apart the spreading tendency increases and the
condition of things shown in the next cut, Fig. 162, obtains. There is
an axial line whose prolongations may be supposed to extend
indefinitely, as occupying a position of unstable equilibrium. Here the
existence of a straight and unterminated line of force may be assumed.

A direction is predicated to lines of force corresponding with the
direction of an electric current. They are assumed to start from a
positively charged and to go towards a negatively charged surface. A
positively charged body placed in an electrostatic field of force will
be repelled from the region of positive into or towards the region of
negative potential following the direction of the lines of force, not
moving transversely to them, and having no transverse component in its
motion.

[Transcriber's note: More precisely, "A positively charged body placed
in an electrostatic field of force will be repelled from the region of
positive into or towards the region of negative potential ACCELERATING
in the direction of the lines of force, not ACCELERATING transversely to
them, and having no transverse component in its ACCELERATION."
Previously acquired momentum can produce a transverse component of
VELOCITY.]


Electrostatics.
The division of electric science treating of the phenomena of electric
charge, or of electricity in repose, as contrasted with electro-dynamics
or electricity in motion or in current form. Charges of like sign repel,
and of unlike sign attract each other. The general inductive action is
explained by the use of the electrostatic field of force and
electrostatic lines of force, q. v. The force of attraction and
repulsion of small bodies or virtual points, which are near enough to
each other, vary as the square of the distance nearly, and with the
product of the quantities of the charges of the two bodies.


Electrostatic Refraction.
Dr. Kerr found that certain dielectrics exposed to electric strain by
being placed between two oppositely excited poles of a Holtz machine or
other source of very high tension possess double refracting powers, in
other words can rotate a beam of polarized light, or can develop two
complimentary beams from common light. Bisulphide of carbon shows the
phenomenon well, acting as glass would if the glass were stretched in
the direction of the electrostatic lines of force. To try it with glass,
holes are drilled in a plate and wires from an influence machine are
inserted therein. The discharge being maintained through the glass it
polarizes light.

Synonym--Kerr Effect.


Electrostatic Series.
A table of substances arranged in the order in which they are
electrostatically charged by contact, generally by rubbing against each
other. The following series is due to Faraday. The first members become
positively excited when rubbed with any of the following members, and
vice versa. The first elements correspond to the carbon plate in a
galvanic battery, the succeeding elements to the zinc plate.

Cat, and Bear-skin--Flannel--Ivory--Feathers--Rock Crystal--Flint
Glass--Cotton--Linen--Canvas--White Silk--the Hand--Wood--Shellac--the
Metals (Iron-Copper-Brass-Tin-Silver-Platinum)--Sulphur. There are some
irregularities. A feather lightly drawn over canvas is negatively
electrified; if drawn through folds pressed against it it is positively
excited. Many other exceptions exist, so that the table is of little
value.


236   STANDARD ELECTRICAL DICTIONARY.


Electrostatic Stress.
The stress produced upon a transparent medium in an electrostatic field
of force by which it acquires double refracting or polarizing properties
as regards the action of such medium upon light. (See Electrostatic
Refraction.)


Electro-therapeutics or Therapy.
The science treating of the effects of electricity upon the animal
system in the treatment and diagnosis of disease.


Electrotonus.
An altered condition of functional activity occurring in a nerve
subjected to the passage of an electric current. If the activity is
decreased, which occurs near the anode, the state is one of
anelectrotonus, if the activity is increased which occurs near the
kathode the condition is one of kathelectrotonus.


Electrotype.
The reproduction of a form of type or of an engraving or of the like by
electroplating, for printing purposes. The form of type is pressed upon
a surface of wax contained in a shallow box. The wax is mixed with
plumbago, and if necessary some more is dusted and brushed over its
surface and some iron dust is sprinkled over it also. A matrix or
impression of the type is thus obtained, on which copper is deposited by
electroplating, q. v.


Element, Chemical.
The original forms of matter that cannot be separated into constituents
by any known process. They are about seventy in number. Some of the
rar

Erg-ten.
Ten millions of ergs, or ten meg-ergs.


Escape.
A term applied to leakage of current.


Etching, Electric.
A process of producing an etched plate. The plate is coated with wax,
and the design traced through as in common etching. It is then placed in
a bath and is connected to the positive terminal from a generator, whose
negative is immersed in the same bath, so that the metal is dissolved by
electrolytic action. By attaching to the other terminal and using a
plating bath, a rough relief plate may be secured, by deposition in the
lines of metal by electroplating.

Synonym--Electric Engraving.


246   STANDARD ELECTRICAL DICTIONARY.


Ether.
The ether is a hypothetical thing that was invented to explain the
phenomena of light. Light is theoretically due to transverse vibrations
of the ether. Since the days of Young the conception of the ether has
extended, and now light, "radiant heat," and electricity are all treated
as phenomena of the ether. Electrical attraction and repulsion are
explained by considering them due to local stresses in the ether;
magnetic phenomena as due to local whirlpools therein. The ether was
originally called the luminiferous ether, but the adjective should now
be dropped. Its density is put at 936E-21 that of water, or equal to
that of the atmosphere at 210 miles above the earth's surface. Its
rigidity is about 1E-9 that of steel (see Ten, Powers of); as a whole it
is comparable to an all-pervading jelly, with almost perfect elasticity.
The most complete vacuum is filled with ether.

All this is a hypothesis, for the ether has never been proved to exist.
Whether gravitation will ever be explained by It remains to be seen.

[Transcriber's note: The Michelson-Morley experiment in 1887 (five years
before this book) cast serious doubt on the ether. In 1905 Einstein
explained electromagnetic phenomenon with photons. In 1963 Edward M.
Purcell used special relativity to derive the existence of magnetism and
radiation.]


Eudiometer.
A graduated glass tube for measuring the volumes of gases. In its
simplest form it is simply a cylindrical tube, with a scale etched or
engraved upon it, closed at one end and open at the other. The gas to be
measured is collected in it over a liquid, generally water, dilute
sulphuric acid in the gas voltameter, or mercury. Many different shapes
have been given them by Hoffmann, Ure, Bunsen and others.


Evaporation, Electric.
The superficial sublimation or evaporation of a substance under the
influence of negative electricity. It is one of the effects investigated
by Crookes in his experiments with high vacua. He found that when a
metal, even so infusible as platinum, was exposed to negative
electrification in one of his high vacuum tubes, that it was volatilized
perceptibly. A cadmium electrode heated and electrified negatively was
found to give a strong coating of metal on the walls of the tube. Even
in the open air the evaporation of water was found to be accelerated by
negative electrification.


Exchange, Telephone.
The office to which telephone wires lead in a general telephone system.
In the office by a multiple switch board, or other means, the different
telephones are interconnected by the office attendants, so that any
customers who desire it may be put into communication with each other.
The exchange is often termed the Central Office, although it may be only
a branch office.


Excitability, Faradic.
The action produced in nerve or muscle of the animal system by an
alternating or intermitting high potential discharge from an induction
coil.


247   STANDARD ELECTRICAL DICTIONARY.


Excitability, Galvanic.
The same as Faradic excitability, except that it refers to the effects
of the current from a galvanic battery.


Excitability of Animal System, Electric.
The susceptibility of a nerve or muscle to electric current shown by the
effect produced by its application.


Exciter.
A generator used for exciting the field magnet of a dynamo. In
alternating current dynamos, e. g., of the Westinghouse type, a special
dynamo is used simply to excite the field magnet. In central station
distribution the same is often done for direct current dynamos.


Exosmose, Electric.
The outflowing current of electric osmose. (See Osmose, Electric.)


Expansion, Coefficient of.
The number expressing the proportional increase in size, either length,
area or volume, of a substance under the influence generally of heat.
There are three sets of coefficients, (1) of linear expansion, (2) of
superficial expansion, (3) of cubic expansion or expansion of volume.
The first and third are the only ones much used. They vary for different
substances, and for the same substance at different temperatures. They
are usually expressed as decimals indicating the mixed number referred
to the length or volume of the body at the freezing point as unity.


Expansion, Electric.
(a) The increase in volume of a condenser, when charged
electrostatically. A Leyden jar expands when charged, and contracts when
discharged.

(b) The increase in length of a bar of iron when magnetized.

This is more properly called magnetic expansion or magnetic elongation.


Exploder.
(a) A small magneto-generator for producing a current for heating the
wire in an electric fuse of the Abel type (see Fuse, Electric), and
thereby determining an explosion.

(b) The term may also be applied to a small frictional or influence
machine for producing a spark for exploding a spark fuse.


Explorer.
A coil, similar to a magnetizing coil (see Coil, Magnetizing), used for
investigating the electro-magnetic circuit and for similar purposes. If
placed around an electro-magnet and connected with a galvanometer, it
will produce a deflection, owing to a momentary induced current, upon
any change in the magnet, such as removing or replacing the armature. It
is useful in determining the leakage of lines of force and for general
investigations of that nature. It is often called an exploring coil.
Hughes' Induction Balance (see Induction Balance, Hughes') is sometimes
called a Magnetic Explorer. The exploring coil may be put in circuit
with a galvanometer for quantitative measurements or with a telephone
for qualitative ones.


248   STANDARD ELECTRICAL DICTIONARY.


Extension Bell Call.
A system of relay connection, q. v., by which a bell is made to continue
ringing after the current has ceased coming over the main line. It is
designed to prolong the alarm given by a magneto call bell, q. v., which
latter only rings as long as the magneto handle is turned. A vibrating
electric bell (see Bell, Electric,) is connected in circuit with a local
battery and a switch normally open, but so constructed as to close the
circuit when a current is passed and continue to do so indefinitely. The
distant circuit is connected to this switch. When the magneto is worked
it acts upon the switch, closes the local battery circuit and leaves it
closed, while the bell goes on ringing until the battery is exhausted or
the switch is opened by hand.


Eye, Electro-magnetic.
An apparatus used in exploring a field of electro-magnetic radiations.
It is a piece of copper wire 2 millimeters (.08 inch) in diameter, bent
into an almost complete circle 70 millimeters (.28 inch) in diameter,
with terminals separated by an air gap. This is moved about in the
region under examination, and by the production of a spark indicates the
locality of the loops or venters in systems of stationary waves.