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

by T. O'Conor Sloane

Figs. 62, 63. INCANDESCENT WIRE FUSE. ABEL'S PATENT.

Fig. 64. VON EBNER'S FRICTIONAL ELECTRIC MACHINE FOR
EXPLODING ELECTRIC FUSES OR DETONATORS.
Bi-telephone.
A pair of telephones arranged with a curved connecting arm or spring, so
that they can be simultaneously applied to both ears. They are
self-retaining, staying in position without the use of the hands.
83 STANDARD ELECTRICAL DICTIONARY.
Blasting, Electric.
The ignition of blasting charges of powder or high explosives by the
electric spark, or by the ignition to incandescence (red or white heat)
of a thin wire immersed in or surrounded by powder. Special influence or
frictional electric machines or induction coils are used to produce
sparks, if that method of ignition is employed. For the incandescent
wire a hand magneto is very generally employed. (See Fuse, Electric.)
The cuts, Figs. 62 and 63, show one form of incandescent wire fuse. The
large wires are secured to the capsule, so that no strand can come upon
the small wire within the cavity.
The cut, Fig. 64, shows a frictional electric machine for igniting spark
fuses.
Bleaching, Electric.
Bleaching by agents produced or made available by the direct action of
electricity. Thus if a current under proper conditions is sent through a
solution of common salt (sodium chloride), the electrodes being close
together, the salt is decomposed, chlorine going to one pole and sodium
hydrate to the other. The two substances react upon each other and
combine, forming sodium hypochlorite, which bleaches the tissue immersed
in its solution.
Block System.
A system of signalling on railroads. The essence of the system consists
in having signal posts or stations all along the road at distances
depending on the traffic. The space between each two signal posts is
termed a block. From the signal posts the trains in day time are
signalled by wooden arms termed semaphores, and at night by lanterns.
The arms may be moved by hand or by automatic mechanism depending in
part on electricity for carrying out its functions. Thus in the
Westinghouse system the semaphores are moved by pneumatic cylinders and
pistons, whose air valves are opened and shut by the action of solenoid
magnets, q. v. The current of these magnets is short circuited by
passing trains, so as to let the valves close as the train passes the
signal post. The block system causes the semaphore to be set at "danger"
or "caution," as the train enters the next block. Then the following
train is not allowed to enter the block until the safety signal is
shown. The Westinghouse system provides for two semaphores on a post,
one indicating "danger" as long as the train is on the next block; the
other indicating "caution" as long as the train is on the next two
blocks. The rails form part of the circuit, their joints being bridged
by copper wire throughout the block, and being insulated where the
blocks meet.
Block Wire.
In the block system a wire connecting adjacent block-signal towers or
semaphore poles.
Blow-pipe.
A name sometimes given to an electric experiment illustrating the
repulsion of electrified air particles from a point held at high
relative potential. A metallic point, placed on the prime conductor of
an electric friction or influence machine, becomes highly electrified,
and the air becoming excited is repelled and acts upon the candle flame.
If the candle is placed on the conductor and a point held towards it the
repulsion is still away from the point.
84 STANDARD ELECTRICAL DICTIONARY.
Blow-pipe, Electric Arc.
A name sometimes given to devices for using the voltaic arc to produce
local heating effects. The directive action of the magnet may be used to
force out the arc like a blow-pipe flame, or a blast of air may be
directly applied for the same purpose.
Blue-stone.
A trade name for crystallized copper sulphate, used in Daniell's and
gravity batteries.
Boat, Electric.
A boat propelled by electricity. The electricity drives a motor which
actuates a screw propeller. The current is generally supplied by a
storage battery. When used on rivers charging stations are established
at proper places. When the boat is used as a tender or launch for a
steam ship, such as a war-vessel, the battery is charged by a plant on
board the ship. From their noiselessness electric boats are peculiarly
available for nocturnal torpedo operations, and the universal equipment
of modern war-ships with electric lightning and power plants makes their
use possible at all points. This type is often termed an electric
launch, and most or all electric boats fall under this category.
Bobbins.
A spool of wood or other material wound with insulated wire. In a
tangent galvanometer the bobbin becomes a ring, with a channel to
receive the winding. As the ring is not infinitely large compared to the
needle the tangent law is not absolutely fulfilled. It is most
accurately fulfilled (S. P. Thomson) when the depth of the groove or
channel in the radial direction bears to the breadth in the axial
direction the ratio of square root of 3 to the square root of 2 or
approximately 11 : 9
Body Protector.
A metallic short circuit connected with the wrists and lower legs of the
human body, so that if by accident an active circuit is grounded by the
hands and body of the workman wearing it, most of the current will pass
through the wire conductors, thus avoiding the vital organs of the body.
Boiler Feed, Electric.
An apparatus by which an electric current acting on an electro-magnet,
or other equivalent device, opens the water supply when the water level
in a boiler sinks too low, and cuts off the water supply as the water
level rises.
Boiling.
In secondary batteries the escape of hydrogen and oxygen gas when the
battery is charged. The bubbling of the escaping gases produces the
effect of boiling.
85 STANDARD ELECTRICAL DICTIONARY.
Boll.
An absolute, or c. g. s., unit of momentum; a gram moving at the rate of
one centimeter per second; a gram-kine (see Kine); a unit proposed by
the British Association.
Bolometer.
An apparatus for detecting small amounts of radiant energy (radiant
heat, so called). A coil suspended by a fine wire or filament so as to
be free to rotate under the effect of force is made up of two parallel
and equal wires, insulated from each other, but connected so that
parallel currents sent through them go in opposite direction through
each. This coil is hung in a strong electro-magnetic field produced by a
large coil surrounding it. When a current passes through the suspended
coil no effect will follow, because the oppositely wound portions
counteract each other exactly. In the circuit with one half of the
suspended coil is an exceedingly thin strip of platinum wire. The other
half of the coil has no strips. Both halves unite after leaving the
coil. If now the strip of platinum is heated its conductivity is
affected and its half of the coil receives less current than the other
half. This disturbs the balance and the coil swings through a small arc.
This apparatus may be made very sensitive, so that an increase of
temperature of 1/1400º F., 9/70000°C. (1/14000º F.) will be perceptible.
Another construction takes the form of a Wheatstone Bridge, q. v., in
whose arms are introduced resistances consisting of bands of iron, .5
Millimeter wide (.02 inches), .004 millimeter (.00016 inch) thick, and
folded on themselves 14 times so as to make a rectangular grating, 17 x
12 millimeters (.68 x .48 inch). The least difference of heat applied to
the grating affects the galvanometer.
Synonym-Thermic Balance.
Boreal Pole.
The south pointing pole of the magnet. (See Austral Pole.)
Bot.
A colloquial expression for the English Board of Trade unit of
Electrical Supply. It is formed of the initials of the words "Board of
Trade." (See Unit, Board of Trade.)
Box Bridge.
A constriction of Wheatstone's Bridge in which the necessary resistance
coils are contained in a single box with plugs for throwing the coils in
and out of circuit, and connections to bring the coils into the
different arms of the system. The cut shows a box bridge. Connections
for the galvanometer, battery wires, and terminals of the unknown
resistance are provided, by which its resistances and the connections
are brought into the exact relations indicated in the conventional
diagram of Wheatstone's bridge. (See Wheatstone's Bridge.)
Referring to the cut, the battery wire, say from the zinc plate,
connects at A1, thereby reaching A, its true connecting point. To B1 one
end of the galvanometer circuit or lead is attached, thereby reaching B,
its true connecting point. To C are connected the other end from the
galvanometer and one end of the unknown resistance. The other end of the
unknown resistance, and the other end of the battery wire, in this case
from the carbon plate, connect to D. At G is an infinity plug, as it is
called. When out it breaks the circuit.
In use after the connections are made the key is depressed and the
galvanometer observed. The resistance is changed until no action of the
galvanometer is produced by closing the circuit when the ratio of the
resistances of the arms gives the proportion for calculating the unknown
resistances.
Synonym--Commercial Wheatstone Bridge, or commercial form of same.

Fig. 65. TOP OF BOX BRIDGE.
86 STANDARD ELECTRICAL DICTIONARY.
Boxing the Compass.
Naming the thirty-two points of the compass in order, and in sequence to
any point called out at random. There are many exercises in the relative
sailing points and bearings that come under the same head. Thus the
direction of two given points being given by names of the compass
points, it may be required to state the number of points intervening.
Brake, Electro-magnetic.
A brake to stop a wheel from rotating. It comprises a shoe, or sometimes
a ring, which by electro-magnetic attraction is drawn against the
rotating wheel, thus preventing it from turning, or tending to bring it
to rest. (See Electro-magnet, Annular.)

Fig. 66. ELECTRIC BRAKE.
87 STANDARD ELECTRICAL DICTIONARY.
Branch.
A conductor branching from a main line. Sometimes the term is restricted
to a principal conductor, from which current is distributed.
Branch Block.
In electric wiring of buildings, a block of porcelain or other material
with grooves, holes and screws for the connection of branch wires to a
main wire. Its functions are not only to afford a basis for connecting
the wires, but also to contain safety fuses. As when a branch wire is
taken off, fuses have to be put in its line, the branch block carries
these also. One end of each fuse connects with a main wire, the other
end connects with one of the wires of the branch leader or wire.
Porcelain is a favorite material for them, as the fusing or "blowing
out" of the safety fuses cannot set it on fire.
Branch Conductor.
A parallel or shunt conductor.
Brazing, Electric.
Brazing in which the spelter is melted by means of electricity; either
current incandescence or the voltaic arc may be used. It is identical in
general with electric welding. (See Welding, Electric.)
Branding, Electric.
A system of branding in which the heat of electrically ignited or
incandescent conductors is used to produce or burn in the marks upon the
surface. For the alternating current a small transformer is connected to
or forms part of the tool.
88 STANDARD ELECTRICAL DICTIONARY.
Brassing.
The deposition of a coating of brass by electrolysis. The plating bath
contains both copper and zinc. As anode a plate of brass is used. The
operation must be constantly watched. The deposition of both metals goes
on simultaneously, so that a virtual alloy is deposited. By changing
the depth of immersion of the anode the color of the deposit is varied.
As a formula for a brassing bath the following are typical. They are
expressed in parts by weight.
(a) For iron and steel.
I.
Sodium Bisulphate, 200
Potassium Cyanide, 70 per cent., 500
Sodium Carbonate, 1,000
Water, 8,000
II.
Copper Acetate, 125
Zinc Chloride, 100
Water, 2,000
Add the second solution to the first.
(b) For zinc.
I.
Sodium Bisulphate, 700
Potassium Cyanide, 70 per cent., 1,000
Water, 20,000
II.
Copper Acetate, 350
Zinc Chloride, 350
Aqua Ammoniae, 400
Water, 5,000
Add the second solution to the first.
Use a brass anode; add more zinc to produce a greenish color; more
copper for a red color. A weak current gives a red color; a strong
current lightens the color. The battery power can be altered, a larger
or smaller anode can be used, or a copper or zinc anode can be used to
change the color of the deposit. The bath may vary from 1.036 to 1.100
sp. gr., without harm.
Break.
A point where an electric conductor is cut, broken, or opened by a
switch or other device, or simply by discontinuity of the wires.
Break-down Switch.
A switch used in the three-wire system to provide for the discontinuance
of the running of one of the dynamos.
By connecting the positive and negative bus wires to one terminal of the
active dynamo, and the neutral bus wire to the other terminal, one
dynamo will supply the current and the system operates like a two-wire
system, but can only be used for half its normal capacity.
Breaking Weight.
The weight which, applied in tension, will break a prism or cylinder, as
an electric current conductor.
89 STANDARD ELECTRICAL DICTIONARY.
Breath Figures, Electric.
If a conductor is electrified and placed upon a piece of glass, it will
electrify the glass in contact with it by conduction or discharge. On
removing the conductor the glass remains electrified. The localized
electrification is shown by breathing gently on the glass, when a
species of image of the conductor is produced by the condensed moisture.
A coin is often used for conductor.
Breeze, Electric.
A term in medical electricity, used to designate the silent or brush
discharge of high tension electricity. As an instance of its employment,
the electric head bath (see Bath, Electric Head,) may be cited. The
patient forming one electrode, being insulated and connected to one of
the conductors, the other conductor, on being brought near his person,
discharges into his body.
Bridge.
(a) A special bar of copper connecting the dynamos to the bus wire, q. v.,
in electric lighting or power stations.
(b) Wheatstone's bridge, q. v., and its many modifications, all of which
may be consulted throughout these pages.
British Association Bridge.
The type of Wheatstone bridge used by the committee of the association
in determining the B. A. ohm; the meter bridge, q. v.
Broadside Method.
A method of determining the magnetic moment of a magnet. The magnet, n,
s, under examination is fixed so that it is at right angles to the
magnetic meridian, M, R, which passes through its own center and that of
a compass needle. From the deflection of the latter the moment is
calculated.

Fig. 67. BROADSIDE METHOD.
Bronzing.
In electro-plating the deposition of a mixture or virtual alloy of
copper and tin. In general manipulation it resembles the operation of
depositing gold and silver alloy, or of brassing.
For bronzing the following bath is recommended:
Prepare each by itself (a) a solution of copper phosphate and (b) a
solution of stannous chloride in a solution of sodium pyrophosphate. For
a, dissolve recently precipitated copper phosphate in concentrated
solution of sodium pyrophosphate. For b, add to a saturated solution of
sodium pyrophosphate solution of stannous chloride as long as the
precipitate which is formed dissolves. Of these two solutions add to a
solution of sodium pyrophosphate which contains about 1.75 oz. of the
salt to the quart, until the precipitate appears quickly and of the
desired color. For anodes use cast bronze plates. Sodium phosphate must
be added from time to time; if the deposit is too light add copper
solution, if too dark add tin solution. (W. T. Brannt.)
90 STANDARD ELECTRICAL DICTIONARY.
Brush.
In electric current generators and motors, the pieces of copper or other
material that bear against the cylindrical surface of the commutator are
thus termed. Many different constructions have been employed. Some have
employed little wheels or discs bearing against and rotating on the
surface of the commutator. A bundle of copper strips is often employed,
placed flatwise. Sometimes the same are used, but are placed edgewise.
Wire in bundles, soldered together at their distant ends have been
employed. Carbon brushes, which are simply rods or slabs of carbon, are
used with much success.
Synonym--Collecting Brush.
Brush, Carbon.
A brush for a dynamo or motor, which consists of a plate or rod of
carbon, held in a brush holder and pressed against the commutator
surface.
Brushes, Adjustment of.
In electric current generators and motors, the brushes which bear upon
the commutator when the machine is in action need occasional adjustment.
This is effected by shifting them until sparking between them and the
commutator is nearly or quite suppressed.