Cyclopedia of Telephony and Telegraphy, Vol. 1 A General Reference Work on Telephony, etc. etc.

Definitions. As already stated those switchboards which are adapted to work in conjunction with magneto telephones are called magneto switchboards. The signals on such switchboa...

Electromagnet. The physical thing which we call an electromagnet, consisting of a coil or helix of wire, the turns of which are insulated from each other, and within which is us...

The problem which confronts one in the production of a system of selective ringing on party lines is that of causing the bell of any chosen one of the several parties on a circu...

Galvani, an Italian physician, discovered, in 1786, that a current of electricity could be produced by chemical action. In 1800, Volta, a physicist, also an Italian, threw furth...

Any of the heating hazards described in the foregoing chapter may cause currents which will damage apparatus. All devices for the protection of apparatus from such damage, opera...

The methods by which current is supplied to the transmitter of a telephone for energizing it, may be classified under two divisions: first, those where the battery or other sour...

Method of Signaling. The ordinary apparatus, by which speech is received telephonically, is not capable of making sufficiently loud sounds to attract the attention of people at...

Variable Resistance. As already pointed out in Chapter II, the variable-resistance method of producing current waves, corresponding to sound waves for telephonic transmission, i...

We have considered what may be called the elemental parts of a complete telephone; that is, the receiver, transmitter, hook switch, battery, generator, call bell, condenser, and...

_The line is a path over which the telephone current passes from telephone to telephone._ The term "telephone line circuit" is equivalent. "Line" and "line circuit" mean slightl...

The art of telephony in its present form has for its problem so to relate two diaphragms and an electrical system that one diaphragm will respond to all the fundamental and harm...

The party-line problem in rural districts is somewhat different from that within urban limits. In the latter cases, owing to the closer grouping of the subscribers, it is not no...

The telephone receiver is the device which translates the energy of the voice currents into the energy of corresponding sound waves. All telephone receivers today are of the ele...

A party line is a line that is for the joint use of several stations. It is, therefore, a line that connects a central office with two or more subscribers' stations, or where no...

Purpose. In complete telephone instruments, comprising both talking and signaling apparatus, it is obviously desirable that the two sets of apparatus, for talking and signaling...

Transmitters--Variable Resistance--Materials--Single and Multiple Electrodes--Solid-Back Transmitter--Types of Transmitters--Electrodes--Packing--Acousticon Transmitter--Switchb...

It will be noticed that the ringer and the relay coil _6_ at the first station are bridged across the sides of the line leading to the central office. In like manner the bell an...

Charge. A conducting body insulated from all other bodies will receive and hold a certain amount of electricity (a charge), if subjected to an electrical potential. Thus, referr...

Up to this point only those classes of telephone service which could be given between two or more stations on a single line have been considered. Very soon after the practical c...

All telephone systems are exposed to certain electrical hazards. When these hazards become actively operative as causes, harmful results ensue. The harmful results are of two ki...

Audible Signals. _Telegraph Sounder._ The earliest electric signal was an audible one, being the telegraph sounder, or the Morse register considered apart from its registering f...

Telephony is the art of reproducing at a distant point, usually by the agency of electricity, sounds produced at a sending point. In this art the elements of two general divisio...

It is often desired to introduce simple ohmic resistance into telephone circuits, in order to limit the current flow, or to create specific differences of potential at given poi...

Possible Ways of Improving Transmission. Practical ways of improving telephone transmission are of two kinds: to improve the lines and to improve the apparatus. The foregoing sh...