Fig. 327. BREGURT'S CAPILLARY TELEPHONE.
Telephone, Carbon.
A telephone transmitter based on the use of carbon as a material whose
resistance is varied by the degree of pressure brought to bear upon it.
Undoubtedly the surface contact between the carbon and the other
conducting material has much to do with the action. Many carbon
telephones have been invented. Under Telephone the Blake transmitter is
described, which is a carbon telephone transmitter. The Edison carbon
transmitter is shown in section in the cut. E is the mouth piece and D
the diaphragm. I is a carbon disc with adjusting screw V. A platinum
plate B B, with ivory button b, is attached to the upper surface of the
carbon disc. C C is an insulating ring. The wire connections shown bring
the disc into circuit. It is connected like a Blake transmitter. It is
now but little used.
Fig. 328. SECTION OF EDISON CARBON TRANSMITTER.
526 STANDARD ELECTRICAL DICTIONARY.
Telephone, Chemical.
A telephone utilizing chemical or electrolytic action in transmitting or
receiving. The electro-motograph is an example of a chemical receiver.
(See Electro-motograph.)
Telephone, Electrostatic.
A telephone utilizing electrostatic disturbances for reproduction of the
voice. In the cut D and C are highly charged electrophori. The
diaphragms A and B when spoken to affect the potential of the
electrophorus so as to produce current variations which will reproduce
the sound. Dolbear and others have invented other forms of transmitters
based on electrostatic action. Receivers have also been constructed. A
simple condenser may be made to reproduce sound by being connected with
a powerful telephone current.
Fig. 329. DIAGRAM OF EDISON'S ELECTROSTATIC TELEPHONE.
Telephone Induction Coil.
The induction coil used in telephone circuits for inducing current on
the main line. It is simply a small coil wound with two separate
circuits of insulated wire. In the Edison telephone the primary coil, in
circuit with the transmitter, is of No. 18 to 24 wire and of 3 to 4 ohms
resistance. The secondary in circuit with the line and receiving
instrument is of No. 36 wire and of 250 ohms resistance. The Bell
telephone induction coil has its primary of No. 18 to 24 wire wound to a
resistance of 1/2 ohm, and its secondary of No. 36 wire, and of 80 ohms
resistance.
527 STANDARD ELECTRICAL DICTIONARY.
Telephone, Reaction.
A form of telephone containing two coils of insulated wire, one of which
is mounted on the disc, and the other on the magnet pole in the usual
way. These coils react upon each other so as to strengthen the effect.
Telephone, Thermo-electric.
A telephone transmitter including a thermo-electric battery, placed in
circuit with the line. A plate of vulcanite faces it. When the sound
waves strike the vulcanite they move it backward and forward. These
movements, owing to the elasticity of the vulcanite, produce minute
changes of temperature in it, which affecting the thermo-electric pile
produce in the circuit currents, which passing through a Bell telephone
cause it to speak. This type of instrument has never been adopted in
practice.
Telephote.
An apparatus for transmitting pictures electrically, the properties of
selenium being utilized for the purpose.
Synonym--Pherope.
Teleseme.
An annunciator, displaying on a dial the object wanted by the person
using it. It is employed to transmit messages from rooms in a hotel to
the office, or for similar functions.
Tele-thermometer.
A thermometer with electric attachment for indicating or recording its
indications at a distance.
Tempering, Electric.
A process of tempering metals by electrically produced heat. The article
is made part of an electric circuit. The current passing through it
heats it, thereby tempering it. For wire the process can be made
continuous. The wire is fed from one roll to another, and if required
one roll may be immersed in a liquid bath or the wire between the rolls
may be led therein. The current is brought to one roll and goes through
the wire to the other. As it does this the wire is constantly fed from
one roll to another. The bath may be used as described to cool it after
the heating. The amount of heating may be regulated by the rate of
motion of the wire.
528 STANDARD ELECTRICAL DICTIONARY.
Ten, Powers of.
This adjunct to calculations has become almost indispensable in working
with units of the C. G. S. system. It consists in using some power of 10
as a multiplier which may be called the factor. The number multiplied
may be called the characteristic. The following are the general
principles.
The power of 10 is shown by an exponent which indicates the number of
ciphers in the multiplier. Thus 10^2 indicates 100; 10^3 indicates 1,000
and so on.
The exponent, if positive, denotes an integral number, as shown in the
preceding paragraph. The exponent, if negative, denotes the reciprocal
of the indicated power of 10. Thus 10^-2 indicates 1/100; 10^-3 indicates
1/1000 and so on.
The compound numbers based on these are reduced by multiplication or
division to simple expressions. Thus: 3.14 X 10^7 = 3.14 X 10,000,000 =
31,400,000. 3.14 X 10^-7 = 3.14/10,000,000 or 314/1000000000. Regard must
be paid to the decimal point as is done here.
To add two or more expressions in this notation if the exponents of the
factors are alike in all respects, add the characteristics and preserve
the same factor. Thus:
(51X 10^6) + (54 X 10^6) = 105 X 10^6.
(9.1 X 10^-9) + (8.7 X 10^-9) = 17.8 X 10^-9.
To subtract one such expression from another, subtract the
characteristics and preserve the same factor. Thus:
(54 X 10^6) - (51 X 10^6) = 3 X 10^6.
If the factors have different exponents of the same sign the factor or
factors of larger exponent must be reduced to the smaller exponent, by
factoring. The characteristic of the expression thus treated is
multiplied by the odd factor. This gives a new expression whose
characteristic is added to the other, and the factor of smaller exponent
is preserved for both,
Thus:
(5 X 10^7) + (5 X10^9) = (5 X 10^7) + (5 X 100 X 10^7) = 505 X 10^7.
The same applies to subtraction. Thus:
(5 X 10^9) - (5 X 10^7) = (5 X 100 X 10^7) - (5 X 10^7) = 495 X 10^7.
If the factors differ in sign, it is generally best to leave the
addition or subtraction to be simply expressed. However, by following
the above rule, it can be done. Thus:
Add
5 X 10^-2 and 5 X 10^3.
5 X 10^3 = 5 X 10^5 X 10^-2
(5 X 10^5 X 10^-2) + (5 X 10^-2) = 500005 X 10^-2
This may be reduced to a fraction 500000/100 = 5000.05.
To multiply add the exponents of the factors, for the new factor, and
multiply the characteristics for a new characteristic. The exponents
must be added algebraically; that is, if of different signs the
numerically smaller one is subtracted from the other one, and its sign
is given the new exponent.
Thus;
(25 X 10^6) X (9 X 10^8) = 225 X 10^14.
(29 X 10^ -8) X (11 X 10^7) = 319 X 10^-1
(9 X 10^8) X (98 X 10^2) = 882 X 10^1
529 STANDARD ELECTRICAL DICTIONARY.
To divide, subtract (algebraically) the exponent of the divisor from
that of the dividend for the exponent of the new factor, and divide the
characteristics one by the other for the new characteristic. Algebraic
subtraction is effected by changing the sign of the subtrahend,
subtracting the numerically smaller number from the larger, and giving
the result the sign of the larger number.
(Thus to subtract 7 from 5 proceed thus; 5 - 7 = -2.)
Thus;
(25 X 10^6) / (5 X 10^8) = 5 X 10^-2
(28 X 10^-8) / (5 X 10^3) = 5.6 X 10^-11
[Transcriber's note: I have replaced ordinary exponential notation by
the more compact and simpler "programming" representation. The last two
example would be:
25E6 / 5E8 = 5E-2
28E-8 / 5E3 = 5.6E-11
]
Tension.
Electro-motive force or potential difference in a current system is
often thus termed. It is to be distinguished from intensity or current
strength, which word it too greatly resembles.
Tension, Electric.
(a) The condition an electrified body is brought into by
electrification, when each molecule repels its neighbor. The condition
is described as one of self-repulsion.
(b) The voltage or potential difference of a circuit is also thus
termed.
Terminal.
The end of any open electric circuit, or of any electric apparatus; as
the terminals of a circuit, dynamo, or battery.
Terminal Pole.
In telegraph line construction the last pole of a series; one beyond
which the line is not carried. Such pole, as the pull of the wires is
all in one direction, requires special staying or support. The regular
line poles are free from this strain, as the wire pulls in both
directions.
Tetanus, Acoustic.
A term in electro-therapeutics. An effect produced on a nerve by very
rapidly alternating induced currents. The currents are produced by an
induction coil with a vibrator giving a musical note. This is a species
of gauge of proper frequency of alternations.
Theatrophone.
An apparatus worked by automatic paying machinery by which a telephone
connection is made with a theatre or opera by the deposition of a coin
in a slot.
Therm.
A unit of heat. It has been proposed by the British Association and
amounts to a redefinition of the smaller calorie. It is the amount of
heat required to raise the temperature of one gram of water one degree
centigrade, starting at the temperature of maximum density of water.
530 STANDARD ELECTRICAL DICTIONARY.
Thermaesthesiometer.
An electro-therapeutic instrument for testing the sensitiveness of the
surface of the body to changes of temperature. Vessels of mercury are
provided with thermometers to indicate their temperature. One vessel is
surrounded by an electric conductor wound in a number of turns. The
temperature is raised by passing a current through this. By successive
applications of the vessels to the same spot upon the skin the power of
differentiating temperatures is determined.
Thermo Call.
(a) An electric alarm or call bell operated by thermo-electric currents.
It may serve as a fire alarm or heat indicator, always bearing in mind
the fact that differential heat is the requisite in a thermo-electric
couple.
(b) See Thermo-electric Call.
Thermo-chemical Battery.
A voltaic battery in which the electro-motive force is generated by
chemical action induced by heat.
The chemical used generally is sodium nitrate or potassium nitrate. The
positive plate is carbon. On heating the battery the nitrate attacks the
carbon, burning it and produces potential difference. For negative plate
some metal unattacked by the nitrate may be employed.
Fig. 330. POUILLET'S THERMO-ELECTRIC BATTERY.
Thermo-electric Battery or Pile.
A number of thermo-electric couples q. v., connected generally in
series.
In Nobili's pile the metals are bismuth and antimony; paper bands
covered with varnish are used to insulate where required. In Becquerel's
pile copper sulphide (artificial) and German silver, (90 copper, 10
nickel) are the two elements. The artificial copper sulphide is made
into slabs 4 inches long, 3/4 inch wide, and 1/2 inch thick (about).
Water is used to keep one set of junctions cool, and gas flames to heat
the other set. In Fig. 331, c, d represent the binding screws. The
couples are mounted on a vertical standard, with adjusting socket and
screw B, so that its lower end can be immersed in cold water, or raised
therefrom as desired.
531 STANDARD ELECTRICAL DICTIONARY.
FIG. 331. BECQUEREL'S THERMO-ELECTRIC BATTERIES.
Fig. 332 shows one couple of the battery. S is artificial antimony
sulphide; M is German silver; m is a protecting plate of German silver
to save the sulphide from wasting in the flame.