The monopoly conferred upon the Postmaster-General by the Telegraph Act 1869 was subsequently extended to telephony and wireless telegraphy, but it does not extend to submarine telegraphy.
A similar installation of inductive telephony, in which telephone currents in one line were made to create others in a nearly parallel and distant line, was established in 1899 between Rathlin Island on the north coast of Ireland and the mainland.
Fleming, The Principles of Electric Wave Telegraphy and Telephony, p. 416, 2nd ed.
Fleming, Hertzian Wave Telegraphy (1905); id., The Principles of Electric Wave Telegraphy and Telephony (2nd ed., 1910); J.
Fleming, An Elementary Manual of Radiotelegraphy and Radio-telephony (1908); H.
Mazotto, Wireless Telegraphy and Telephony, Eng.
Telephony is the art of reproducing sounds at a distance from their source, and a telephone is the instrument employed in sending or receiving such sounds.
The term " telephony " was first used by Philipp Reis of Friedrichsdorf, in a lecture delivered before the Physical Society of Frankfort in 1861.1 But, although this lecture and Reis's subsequent work received considerable notice, little progress was made until the subject was taken up between 1874 and 1876 by Alexander Graham Bell, a native of Edinburgh, then resident in Boston, Mass., U.S.A. Bell, like Reis, employed electricity for the reproduction of sounds; but he attacked the problem in a totally different manner.
The necessary condition for a successful system of telephony is the ability to reproduce these characteristics.
A type of transmitter which has come to be invaluable in connexion with long distance telephony, and which has practically superseded all other forms, is the granular carbon transmitter.
The single-wire earthed circuits used in the early days of telephony were subject to serious disturbances from the induction caused by currents in neighbouring telegraph and electric light wires, and from the varying potential of the earth due to natural or artificial causes.
One of the greatest advances made in the development of the art of telephony was the introduction of the " common battery relay system."
The idea of automatic telephony is to substitute for the operator of the manual exchange an electromechanical or other switching system, which, controlled in its movement by the action of the subscriber, will automatically select, connect and disconnect circuits as desired.
The development of telephony in the United States of America is much greater than anywhere else; on the 1st of January 1907, 5 per cent.
Aluminium conductors have been employed on heavy work in many places, and for telegraphy and telephony they are in frequent demand and give perfect satisfaction.
The principles of telegraphy (land, submarine and wireless) and of telephony are discussed in the articles Telegraph and Telephone, and various electrical instruments are treated in separate articles such as Amperemeter; Electrometer; Galvanometer; Voltmeter; Wheatstone'S Bridge; Potentiometer; Meter, Electric; Electrophorus; Leyden Jar; &C.