Harry Robert Kempe and Emile Garcke

“ Control of the call is thus vested in the operator at the originating exchange, at which point the connexion must be severed before a clearing signal can appear at B.
Party Lines.—A circuit which serves more than one subscriber is termed a "party line." It was originally the practice to place the calling apparatus in series in the line circuit, but the effect of the large impedance introduced by the electromagnets of the call bells was such that not more than two or three persons could be connected without seriously impairing the efficiency of the circuit for speech transmission. ”

“ When the sounding board was spoken to or subjected to sound-waves, the mechanical resistance of the loose electrode, due to its weight, or the spring, or both, served to vary the pressure at the contact, and this gave to the current a form corresponding to the sound-waves, and it was therefore capable of being used as a speaking-telephone transmitter [15] The next transmitter of note was that introduced by Francis Blake, which came into wide use in the United States of America and other countries. In it the electrodes were of platinum and carbon. ”

“ As no practical process of telephone relaying has been devised, it is extremely important that the character of the line should be such as to favour the preservation of the strength and form of the telephone current. In circuits possessing high resistance and capacity and low inductance per mile, telephonic currents are rapidly attenuated, and the higher the frequency the more rapid is the attenuation. ”

“ In pursuance of the report of the select committee, 1898, the Telegraph Act 1899 was passed to enable the Post Office to develop its telephone exchange business, for which a loan of £2,000,000 was sanctioned, and to empower local authorities, subject to certain conditions, to enter upon telephone business. The licence of the National Telephone Company was extended so as to be co-extensive with that of a competitive licence for any locality on condition that the company should afford intercommunication with the telephone systems of the new licensees. ”

“ The Stone system, compared with that of Hayes, possesses the disadvantage that one of the conditions affecting the supply of current to any particular subscriber's circuit is the resistance of the other circuit to which it is connected for the time being. An improvement in this respect has been effected by the insertion of condensers in the cord circuits, coupled with the use of two sets of impedance coils, one set on each side of the condensers. ”

“ The next worker at the telephone, and the one to whom the present great commercial importance of the instrument is due, was Bell. His aim was the production, by means of the undulations of pressure on a membrane caused Bell’s researches. by sound, of an electric current, the strength of which should at every instant vary directly as the pressure varied. [7] His first idea seems to have been to employ the vibrations of the current in an electric circuit, produced by moving the armature of an electromagnet included in the circuit nearer to or farther from the poles of the magnet. ”

“ The subscribers’ lines in an exchange are arranged in groups of 1000, which are divided in turn into sub-groups of 100 each. By means of his first selector the circuit of a calling subscriber is connected to the outgoing end of a junction whose other end terminates upon the incoming portion of a second selector in the thousand group to which the wanted subscriber belongs. The second selector in turn extends the connexion by means of another junction circuit to one of the connector switches in the hundred group wanted, while finally the connector switch completes the connexion. ”

“ At the subscriber's station when the receiver is on the hook switch the circuit is through the call-bell and a condenser. The conditions permit of the circulation of the alternating currents of' low periodic it, which are used for operating the bells, but in respect of the battery the circuit is open until the subscriber lifts the receiver, when the hook switch, thus released, joins the transmitter with one winding 'of an induction coil in series across the circuit. A current then flows and in passing round the circuit operates the line relay, with the result that the calling-lam is lighted. ”

“ Trunk Line Working.—Trunk or long-distance working is complicated by the necessity for recording all calls. The system of the British Post Office is worked as follows: A subscriber desiring a long-distance connexion calls up his local exchange in the ordinary way, and the operator there, being informed that a trunk connexion is desired, extends the subscriber's line to the Post Office by means of a record circuit. At the Post Office a record operator replies and takes particulars of the connexion, and these are entered upon a ticket. ”

“ It is not practicable to connect each subscriber directly to all the others, hence a -system of exchanges has been adopted. The territory in which a telephone administration operates is usually divided into a number of local areas, in each of which one or more exchanges are placed. An exchange is a central station to which wires are brought from the various subscribers in its neighbourhood, any two of whom can be put in telephonic communication with each other when the proper pairs of wires are joined together in the exchange. ”

“ The operator, whose attention is thus attracted, inserts a peg in the jack, then throws over the speaking key of the cord circuit, and having ascertained particulars of the requirement places the other peg of the pair in the nearest multiple jack of the wanted subscriber, whom she proceeds to ring up. In the meantime the calling lamp, has darkened; and each subscriber's line being equipped with a cut-off relay whose function it is to disconnect the calling apparatus while the circuit is in use, the insertion of a peg is immediately followed by the disappearance of the calling signal. ”

“ After the withdrawal of the restriction against the companies erecting trunk wires it became evident that the development of the telephone services throughout the country would be facilitated by complete intercommunication and uniformity of systems, and that economies could be effected by concentration of management. The various companies therefore amalgamated as the National Telephone Company. ”

“ 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. ”

“ The only European country which can be compared with the United Kingdom in telephone development is Germany. With a population of 58 millions there are 10.2 telephones per 1000 of the population in that country compared with 10.15 in Great Britain and Ireland. The development of telephony in the United States of America is much greater than anywhere else ”

“ The Edison Telephone Company of London was formed. Both the Bell and the Edison Companies opened negotiations with the Post Office for the sale of their patents to the government, but without success. The Edison Company announced its intention to start telephone business in London, and the Postmaster-General instituted proceedings against the company for infringement of his monopoly rights under the Telegraph Act 1869. ”

“ Automatic Systems.—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 sensation of sound is produced by rapid fluctuation in the pressure of the atmosphere on the tympanum of the ear. If the fluctuations are irregular and non-periodic, the sound is called a noise; if they are cyclic and follow a regular and sufficiently rapid periodic law, the sound is musical. ”

“ An improvement was effected in this respect by the introduction of the "bridging" system, in which the bells possessing high inductance are placed in parallel between the two wires of the circuit. Although the bells are constantly in circuit their high impedance prevents any appreciable interference with the telephonic currents. In America, on farmers' circuits, ten or more stations are frequently connected to one line; but in England ten is practically the maximum. ”

“ In large towns served by a number of exchanges the junction equipment is an important feature. In many cases from 60 to 80 per cent. of the calls originated at an exchange are for subscribers connected to other exchanges, and in these cases the junction plant forms a considerable fraction of the whole equipment. Moreover each call junction is dealt with by at least two operators. ”

“ While considering that a really efficient Post Office service would afford the best means for securing such competition, it recommended that general, immediate and effective competition should at once be undertaken either by the Post Office or by local authorities. ”

“ The licences within restricted areas having proved unsuitable for the growing business, public opinion appealed to the Post Office to issue new licences applicable to the whole country. All limitations of areas were removed and licensees were allowed to open public call offices but not to receive or deliver written messages, and they were allowed to erect trunk wires. ”

“ In 1906 there were 30,551, equal to 7.2 per cent., more telephone stations in the United Kingdom than in the ten European countries of Austria, Hungary, Belgium, Denmark, Holland, Italy, Norway, Portugal, Russia, Sweden and Switzerland, having a combined population of 288 millions as against a population of 42 millions in the United Kingdom. Apart from France, Germany and Switzerland, there was no European country that had as many telephones working as London. ”

“ When the connecting string is held taut and sounds, such as those of ordinary speech, are produced in front of one of the membranes, pulses corresponding to the fluctuations of the atmospheric pressure are transmitted along the string and communicated to the other membrane, which in its turn communicates them to the air, thus reproducing the sound. ”

“ There are still many magneto exchanges in existence, but when new exchanges are erected only the very smallest are equipped for magneto working, that system having succumbed to the common battery one in the case of all equipments of moderate and large dimensions. ”

“ In Reis’s lecture an apparatus was described which has given rise to much discussion as to priority in the invention of the telephone. The instrument was described in over fifty publications [6] in various countries, and was well known to physicists previous to Bell’s introduction of the electric telephone as a competitor with the electric telegraph. knownReis’s telephone. Reis caused a membrane to open and close an electric circuit at each vibration, thus transmitting as many electric pulses through the circuit as there were vibrations in the sound. ”

“ As the cost of the service varies in proportion to the amount of use, the toll rate is more scientific, and it has the further advantage of discouraging the unnecessary use of the instrument, which causes congestion of traffic at busy hours and also results in lines being “ engaged ” when serious business calls are made. ”

“ To the brass bottom of the case is attached a thin disk of polished hard carbon C, which is slightly less in diameter than the brass bottom, so that the carbon disk almost entirely covers this brass back, leaving only a slight annular space around its edge. The front or cover of the case is a similar button of hard polished carbon D, also slightly smaller in diameter than the cylindrical wall of the box. It is attached to a brass disk E, which is fastened to the centre of the diaphragm F by means of a rivet, and is capable of moving to and fro like a plunger when the diaphragm vibrates. ”

“ The tariff for unlimited use has to be made very high to cover the cost of the additional burdens thrown upon the service, and it only works economically to the individual subscriber who has an exceptionally large number of calls originating from his instrument. ”

“ In large towns telephone distribution by means of open wires is practically impossible, and the employment of cables either laid in the ground or suspended from poles or other overhead supports is necessary. ”

“ During the progress of these operations the A operator connects the originating subscriber to the junction circuit named by the B operator. There is only one signal on the cord circuit at B, and that signal is controlled by exchange A. Each of the subscribers controls a signal at A, and when either or both of the telephones are replaced, the action is indicated by the lamps there. ”

“ As subscribers’ lines are invariably short, the smallest gauge of wire possessing the mechanical strength necessary to withstand the stresses to which it may be subjected can be employed, and bronze wire weighing 40 ℔ per mile is commonly used. ”

“ The Postmaster-General also agreed to lay underground wires for the company at an annual rental of £1 per mile of double wire in any local area in which the company was operating, but not in areas in which the municipalities had established exchanges. Free intercommunication was established by the agreement between the subscribers of the company and those of the Post Office, and a scale of charges was adopted or arranged to be agreed as binding on both the Post Office and the company. ”