Fig. 9. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.
Alarm, Electric.
An appliance for calling attention, generally by
ringing a bell. It is used to notify of water-level in boilers or tanks,
of entrance of a house, or of other things as desired. It is evident
that any number of alarms could be contrived.
18 STANDARD ELECTRICAL DICTIONARY.
Alarm, Fire and Heat.
An alarm for giving notice of the existence of a conflagration. Such are
sometimes operated by a compound bar thermostat (see Thermostat), which
on a given elevation of temperature closes a circuit and rings an
electric bell. Sometimes the expansion of a column of mercury when
heated is used. This, by coming in contact with one or two platinum
points, completes a circuit, and rings the bell.
The identical apparatus may be used in living rooms, greenhouses.
factories and elsewhere, to give an alarm when the temperature rises or
falls beyond predetermined limits.
Alarm, Overflow.
An alarm to indicate an overflow of water has been suggested on the
lines of a contact completed by water, or of the elements of a battery
which would be made active by water. Thus two sheets of metal might be
separated by bibulous paper charged with salt. If these sheets were
terminals of a circuit including a bell and battery, when water reached
them the circuit would be closed and the bell would ring. It was also
proposed to use one copper and one zinc sheet so as to constitute a
battery in itself, to be thrown into action by moisture. These contacts
or inactive batteries could be distributed where water from an overflow
would be most likely to reach them.
Alarm, Water Level.
An alarm operated by a change of water level in a tank or boiler. By a
float a contact is made as it rises with the water. Another float may be
arranged to fall and close a contact as the level falls. The closing of
the contacts rings an electric bell to notify the attendant in charge.
Alcohol, Electrical Rectification of.
A current of electricity passed through impure alcohol between zinc
electrodes is found to improve its quality. This it does by decomposing
the water present. The nascent hydrogen combines with the aldehydes,
converting them into alcohols while the oxygen combines with the zinc
electrode.
Alignment.
The placing in or occupying of the same straight line. The bearings of a
shaft in dynamos, engines, and other machinery have to be in accurate
alignment.
Allotropy.
The power of existing in several modifications possessed by some
substances, notably by chemical elements. Instances of the allotropic
state are found in carbon which exists as charcoal, as graphite
(plumbago or black lead), and as the diamond. All three are the same
elemental substance, although differing in every physical and electrical
property.
19 STANDARD ELECTRICAL DICTIONARY.
Alloy.
A mixture, produced almost universally by fusion, of two or more metals.
Sometimes alloys seem to be chemical compounds, as shown by their having
generally a melting point lower than the average of those of their
constituents. An alloy of a metal with mercury is termed an amalgam. An
important application in electricity is the use of fusible alloys for
fire alarms or for safety fuses. German silver is also of importance for
resistance coils, and palladium alloys are used for unmagnetizable
watches. An alloy of wrought iron with manganese is almost
unmagnetizable, and has been proposed for use in ship building to avoid
errors of the compass.
Alloys or what are practically such can be deposited by electrolysis in
the electro- plater's bath. We give the composition of some alloys
interesting to the electrician.
Solder: Lead 1 part Tin 2 parts
" " " 1 "
" " " 2 "
German Silver: Copper, 2 parts; Nickel, 1 part;
Zinc, 1 part (used for resistances).
Platinum, Silver Alloys: Platinum, 1 part;
silver, 2 parts (used for resistances.)
Palladium alloys for watch springs. (See Palladium.)
Alphabet, Telegraphic.
The combinations of sounds, of dots and dashes marked on paper, of
right-hand and left-hand deflections of a needle, of bells of different
notes, or of other symbols by which a fixed combination is expressed for
each character of the alphabet, for numerals, and for punctuation. While
the code is designed for telegraphic uses it can be used not only for
the conveyance of signals and messages by the electrical telegraphs, but
also by any semaphoric or visual system, as by flashes of light,
movements of a flag or even of the arms of the person signalling.
In the English and continental needle telegraphy in which the message is
transmitted by the movements of an index normally vertical, but
oscillating to one side or the other under the influence of the current,
the latter being controlled by the transmitter of the message, the left
hand swings of the needle are interpreted as dots, the right hand as
dashes.
This system enables one alphabet to be translated into the other, or
virtually one alphabet answers for both Morse and needle transmitters.
There are two principal telegraphic alphabets, the American Morse and
the International codes. They are very similar, their essential
distinction being that spaces are used in the American code, while they
are excluded from the International code.
In the American Morse system the message is now universally received by
sound. (See Sounder--Sound Reading.)
20 STANDARD ELECTRICAL DICTIONARY.
The two codes or telegraphic alphabets are given here.
THE INTERNATIONAL ALPHABET.
Parenthesis, - . - - . -
Understand, ... - .
I don't understand, ..-- ....--..
Wait, .-. . .
Erase, ... ... ...
Call signal, -.-.-.-
End of message, .-.-.-.
Cleared out all right, .-..-..-.
A .- L .-.. W .--
B -... M -- X -..-
C -.-. N -. Y -.--
D -.. O --- Z --..
E . P .--.
F ..-. Q --.- Ch ----
G --. R .-. Ä .-.-
H .... S ... Ö ---.
I .. T - Ü ..--
J .--- U ..- É ..-..
K -.- V ...- Ñ --.--
NUMERALS
1 .---- 4 ....- 8 ---..
2 ..--- 5 ..... 9 ----.
3 ...-- 6 -.... 0 -----
7 --...
[Transcriber's note: The original image of the dot/dash pattern is somewhat
ambiguous. Since there may be differences from contemporary specifications,
the original image is included.]
[Image of page 20: THE INTERNATIONAL ALPHABET.]
21 STANDARD ELECTRICAL DICTIONARY.
PUNCTUATION, ETC.,
Period (.) ... ...
Comma (,) .-.-.-
Query(?) ..--..
Exclamation (!) --..--
Apostrophe (') .----.
Hyphen (-) -....-
Fresh paragraph, .-.-..
Inverted commas, -..-.
THE AMERICAN ALPHABET.
A .- L ----(Continuous) W .--
B -... M -- X .-..
C ..s. N -. Y ..s..
D -.. O .s. Z ….
E . P .....
F .-. Q ..-. Ch ----
G --. R .s.. Ä .-.-
H .... S ... Ö ---.
I .. T - Ü ..--
J - . - . U ..- É ..-..
K -.- V ...- Ñ --.--
NUMERALS
1 .--. 4 ....- 8 -....
2 ..-.. 5 --- 9 -..-
3 ...-. 6 ... ... 0 -----(Continuous)
7 --..
[Transcriber's Note: The "s" in the American Code indicates a "space". I
leave the following to the reader's imagination. See the original
image.]
Comma (,)
Semicolon (;)
Colon (:)
Colon Dash (:~)
Period (.)
Interrogation (?)
Exclamation (!)
Dash (-)
Hyphen (-)
Pound Sterling (£)
Shilling Mark ( )
[Image of page 21: THE AMERICAN ALPHABET.]
22 STANDARD ELECTRICAL DICTIONARY.
[Transcriber's Note: I leave these to the reader's imagination. See the
following original image.]
Dollars ($)
Decimal Point (.)
Cents (c)
Paragraph ()
Pence (d.)
Fractional Mark (--)
Capitalized Letter
Italics or Underline
Colon followed by Quotation :"
Parenthesis ( )
Brackets [ ]
Quotation Marks " "
Quotation within a Quotation " ' ' "
[Image of page 22: THE AMERICAN ALPHABET.]
The principal differences in the two codes are the use of spaces in the
American code, such being excluded from the International code. This
affects the letters C, R, Y, & Z.
The following diagram, due to Commandant Perian, enables the letter
corresponding to an International code sign to be rapidly found with the
exception of R.
<- dot start dash ->
/ \
E T
/ \ / \
I A N M
/ \ / \ / \ / \
S U R W D K G O
/ \ / \ / \ / \ / \ / \ / \ / \
H V F U L A P J B X C Y Z Q Ô CH
Fig. 10. Diagram for translating the Morse Alphabet.
In order to find what letter corresponds to a given sign, starting from
the top of the diagram, each line is traced down to a bifurcation,
taking the right hand line of each bifurcation for a dash, and the left
hand line for a dot, and stopping when the dots and dashes are used up.
Thus, for example,
the signal -.- - leads us to the letter d,
the signal - - - - to the letter j and so on.
23 STANDARD ELECTRICAL DICTIONARY.
Alternating. adj.
Term descriptive of a current changing periodically in
direction. (See Current, Alternating.)
Synonyms--Oscillatory--periodic--undulatory--harmonic.
Alternating Current Arc.
The arc produced by the alternating current. It presents several
peculiarities. With an insufficient number of alternations per second it
goes out. As the carbons wear away equally it is adopted for such lamps
as the Jablochkoff candle, (see Candle, Jablochkoff). As no crater is
formed the light is disseminated equally both up and down. For this
reason to get full downward illumination a reflector is recommended.
Alternating Current System.
A system of electric distribution employing the alternating current. For
transmission in the open air or in conduits a high potential circuit is
used, from 1,000 to 10,000 volts being maintained at the central
station. Two leads unconnected at the end lead from the station. Where
current is desired a converter or transformer (see Converter) is placed,
whose primary is connected to the two leads bridging the interval
between them. From the secondary the house leads are taken with an
initial potential in some cases of 50 volts. The converters are thus all
placed in parallel. By law or insurance rules the converters are
generally kept outside of buildings. Where no secondary current is taken
from the converters very little primary current passes them on account
of their counter-electromotive force. As more secondary current is taken
the primary increases and this accommodation of one to the other is one
of the interesting and valuable features. Street lamps are sometimes
connected in series. Each lamp in such case is in parallel with a small
coil with iron core. While the lamp is intact little current passes
through the coil. If the lamp is broken, then the converter impedes the
current by its spurious resistance, q. v., just enough to represent and
replace the resistance of the extinguished and broken lamp filament.
(See Meter, Alternating Current; Motor, Alternating Current.)
Alternation.
The change in direction of a current. The number of such changes is
expressed as number of alternations; thus a current may have a frequency
of 500 or 20,000 alternations per second.
[Transcriber's note: One alternation per second is now called one hertz.]
Alternation, Complete.
A double alternation; a change from one direction
to the other and back again to the original phase. A symbol derived from
its graphic representation by a sine curve is used to indicate it. The
symbol is ~
24 STANDARD ELECTRICAL DICTIONARY.
Alternative Path.
A second path for a current appearing as a disruptive
discharge. Where two paths are offered the discharge, as it is of
alternating or oscillatory type, selects the path of least
self-induction. Thus a thick bar of copper, with no air gap, may be
abandoned by the current in favor of a small iron wire with an air gap,
but which has less self-induction.
The lightning arresters, q. v., for the protection of telegraph offices
are sometimes based on these principles. A path of very high resistance
but of small self-induction is offered between the line and the earth.
This the lightning discharge selects in preference to the instruments
with their iron cores, as the latter are of very high self-induction.
Alternator.
A dynamo electric generator supplying an alternating current. (See
Dynamo, Alternating Current.)
Synonym--Alternating current generator or dynamo.
Alternator, Constant Current.
An alternating current dynamo supplying a current of unvarying virtual
amperage. Alternators of this type are constructed with an armature of
high self-induction. Sometimes fine winding contained in deep peripheral
notches in the core-discs is employed to magnify the self-induction.
Such generators are employed for series lighting, especially
arc-lighting.
Aluminum.
A metal; one of the elements; symbol: Al.
Atomic weight: 27.4. Equivalent: 9.13. Valency: 3.
Specific gravity: 2.6. It is a conductor of electricity.
Relative resistance annealed, (Silver = 1) 1.935
Specific resistance at 0ºC (32°F.) 2.912 microhms
Resistance of a wire at 0ºC (32°F.)
a) 1 foot long, weighing 1 grain, 0.1074 ohms.
b) 1 foot long, 1/1000 inch thick, 17.53 "
c) 1 meter long, weighing 1 gram, 0.0749 "
d) 1 meter long, 1 millimeter thick 0.03710 "
Resistance of a 1-inch cube at 0ºC (32°F.) 1.147 microhms
Electro-chemical equivalent. .0958 (hydrogen == .0105)
25 STANDARD ELECTRICAL DICTIONARY.
Amalgam.
(a) A combination or alloy in which one of the constituents is mercury.
Usually the term is applied to an alloy of a single metal with mercury.
Some metals readily form amalgams; such metals are: Gold, zinc, silver,
lead and others; some, such as platinum and iron, form amalgams only
under exceptional circumstances.
(b) The word is also applied to compositions for application to the
cushions of frictional electric machine in which cases it is often a
misnomer. True amalgams used for this purpose are made as follows:
(a) Tin, 1 part; Zinc, 1 part; Mercury, 2 parts (Kienmayer).
(b) Tin, 2 parts; Zinc, 3 parts.
(c) Tin, 3 parts; Zinc, 5 parts; Mercury, 4 parts.
(d) Zinc, 1 part: Mercury, 4 parts; Mercury, 9 parts. [sic]
The tin, if such is used, (formula a, b and c) is first melted, the zinc
is added in successive portions. The mercury, which must be heated, is
slowly poured into the melted alloy after removal of the latter from the
fire, and the mixture, while making, is constantly stirred. It is kept
stirred or rubbed in a mortar until cold. Sometimes it is poured into
water and kept in constant agitation until cold. It is thus obtained in
a granular condition, and is pounded in a mortar until reduced to
powder. It must be dried and kept in tightly stopped bottles and is
applied to the cushions after they have been greased. It is to be
noticed that it is said that alloy (d) requires no pulverization beyond
constant rubbing in a mortar as it cools. Sometimes the amalgam is
shaken about in a wooden tray with chalk while cooling. The action of
amalgams is not very clearly understood. Some claim that there is a
chemical action, others that they simply act as conductors, others that
they are more highly negative to the glass than the leather of the
cushions.
Graphite or sulphide of tin (mosaic gold) are sometimes used to coat the
cushions; it is these that are sometimes incorrectly called amalgams.
Amalgamation.
The application of mercury to a metal with which it forms an amalgam, or
with which it amalgamates. Battery zincs are amalgamated in two ways. In
the immersion method, the plate is dipped into an acid solution of
mercuric chloride or nitrate. The latter is best. In the direct
application method the plate is first wet all over with dilute acid and
a little mercury is dropped upon it and is rubbed over the surface with
a rag or, what is better, with a piece of galvanized iron. A very little
mercury answers the purpose. The whole surface of the plate should be
left as bright as silver. (See Action, Local.)
Amber.
Amber is a fossil resin, supposed to be a product of the extinct Pinites
Succinifer and other coniferous trees. Most of it is gathered on the
shores of the Baltic between Koenigsberg and Memel. It is also found in
small pieces at Gay Head, Mass., and in New Jersey green sand. It is
found among the prehistoric remains of the Swiss Lake dwellers. When
rubbed with a cloth it becomes excited with negative electricity. The
Greek word for it is electron, which gave the name electricity to the
modern science. Thales of Miletus, 600 B. C., and Theophrastus, about
300 B. C., both mention its electric properties or power of attracting
small objects when rubbed.
26 STANDARD ELECTRICAL DICTIONARY.
Ammeter.
The commercial name for an ampere-meter, an instrument designed
to show by direct reading the number of amperes of current which are
passing through a circuit.
A great variety of ammeters have been invented, based on different
principles. The definitions following this one give some idea of the
lines of construction followed.
Synonym--Ampere meter.
Ammeter, Ayrton's.
A direct reading instrument for measuring current intensity.
A solenoid receives the current. In the axis of the solenoid an iron
tube is suspended by a long spiral spring that passes down within it,
and the upper end of which spring is fastened to the glass top of the
instrument. The tube is provided with proper guides so as to maintain a
vertical position, and is free to rotate. Its upper end carries an
index.
The whole operates as a magnifying device. A slight longitudinal
displacement of the tube causes it to rotate through a considerable
angle by the action of the spring. By properly proportioning the parts,
the angle of displacement of the index is directly proportional to the
current between 15º and 270º angular displacement.
The same instrument is wound for use as a volt-meter.
Its principal fault is its restricted range.
Ammeter, Commutator.
A commutator ammeter is one whose windings consist of separate strands,
each of any desired number of turns, and provided with a commutating
attachment for throwing them into series or into parallel as desired.
The essential condition is that all the wires shall be of equal
resistance and of equal number of turns. Such an instrument can be used
for heavy or light currents. Two sets of graduations are marked on its
scale if it is a calibrated instrument. (See Calibration.) Commutator
volt-meters are constructed on the same principle.
Ammeter, Cunynghame's.
A modification of the Siemens' electro-dynamometer. (See
Electro-dynamometer, Siemens'.) An electro-magnet with very massive core
is excited by the current. As the core is of small reluctance the
strength of the magnet is nearly proportional to the current strength.
Between the poles of the magnet a soft iron armature or induced magnet
is pivoted. It carries a pointer so adjusted that when the axis of the
soft iron magnet is at an angle of about 30º with the line joining the
poles of the electro-magnet the pointer will indicate zero.
The soft iron armature is so massive that the magnetism induced in it is
proportional to the strength of the electro-magnet. Hence the couple
exerted by the electro-magnet on the pivoted armature will be
proportional to the square of the current.
The armature is retained in place by a spiral spring lying in line with
its axis of rotation. The instrument is operated as a zero reading
instrument. The current is passed through it. The needle is deflected;
it is brought back to zero by turning a milled head which twists the
spring. The current will be proportional to the square root of the angle
of displacement of the milled head. A scale with index is provided,
giving directly the square roots of the angle over which the pointer is
moved.
The same instrument is wound for use as a volt-meter.
27 STANDARD ELECTRICAL DICTIONARY.
Ammeter, Eccentric Iron Disc.
This ammeter comprises a cylindrical electro-magnet excited by the
current to be measured. A disc of iron free to rotate is suspended on
pivots below it. A piece is cut off the disc at one part of its
periphery so as to give more metal to one side than to the other. In its
zero position this portion of the disc swings towards the magnet. As the
latter is more and more excited the other or more projecting portion of
the disc turns towards it, being attracted like an armature, and moves
against the force of gravity, the disc rotating. An index attached to
the disc swings over the face of a graduated scale. The disc is so
counterpoised that in its natural position the index points to zero.
Ammeter, Electro-magnetic.
An ammeter depending for its working upon the action of an
electro-magnet, which is excited by the current to be measured.
Ammeter, Gravity.
An ammeter whose hand or index is drawn into the zero position by
gravity, and whose displacement therefrom is produced by the action of
the current to be measured.
Fig. 11. GRAVITY SOLENOID AMMETER.
Ammeter, Magnetic Vane.
A fixed plate of soft iron is placed within a coil. Facing it is a
second disc free to move or swing on an axis. When the field is excited
the two repel each other because like polarity is induced in each, and
the motion of the movable disc indicates the strength of the current.
The same instrument is wound for high resistance and constitutes a
Magnetic Vane Voltmeter.
28 STANDARD ELECTRICAL DICTIONARY.
Ammeter, Magnifying Spring.
A solenoid ammeter in which a spiral spring is used to convert the
longitudinal motion of the armature or movable core into a rotary motion
(see Ammeter, Ayrton's) and magnify the apparent range of motion.
Ammeter, Permanent Magnet.
An ammeter with a magnetic field produced by a permanent magnet.
Ammeter, Solenoid.
An ammeter in which the attraction, when a current is passing through
it, exerted by a hollow coil of wire upon an iron bar or tube in line
with its axis, is utilized to indicate the strength of current. The bar
is drawn into the coil to different extents proportional to the
attraction. As an example see Ammeter, Ayrton's, and cut of Gravity
Ammeter.
Ammeter, Spring.
An ammeter in which the part moved by the current is controlled or
brought to the zero position by a spring.
Ammeter, Steel Yard.
A solenoid ammeter in which the solenoid core is suspended vertically
from the short end of a steel yard fitted with a sliding weight. The
current passes through the solenoid coil and attracts or draws downwards
the coil. A sliding weight is moved in and out on the long steel-yard
arm which is graduated for amperes. In use the weight is slid out until
the arm is in equipose; the divisions give the amperes.