LONDON'S TELEPHONES.

New Zealand Herald, Volume LXIII, Issue 19502, 4 December 1926, Page 12

LONDON'S TELEPHONES.

CHANGE TO AUTOMATICS,, FOURTEEN YEARS TO COMPLETE. It was hoped at one time that the first London automatic telephone exchange would be opened before the end of this year. Delays owing to the industrial position caused by the coal stoppage have, however, thrown the work back some months, ami the most optimistic estimate of the date of completion of - the first automatic exchange is now April, while it is quite possible that the opening will not take place before June. Three exchanges, Holborn, Bishopsgate and Sloan, are racing for the honour of being the first to be completed, and whichever is sucessful the other two will probably be only a few days • behind The Western exchange will come next, and may be completed by the end of next year. Some idea of the magnitude of the work to' be done in preparation for automatic telephony is shown iby the fact that the Holbovn exchange, with 10,000 subscribers, requires 140,000 re lays, 8500 switches, 232 directors, 1520 incoming junctions. 1700 outgoing junctions, 10,000,000 soldered connections, and 5500 miles of wire. It is proposed ultimately to provide automatic telephones for all subscribers within a. tten-railes radius of London, and 138 antomsitic telephone exchanges "toill replace the existing 70 exchanges in the area affected. Once the work of trans formation is in full swing it is expected that a new automatic exchange will bp opened every five or six weeks, but even then it wil! probably be 1940 before the automatic. system m London .is com pleted The initiiil difficulty when the transfei to, automatic telephony was decided upon was the working of the automatic and manual systems side by side This has been overcome by the provision of a tan dem exchange which will be situated in the same building as the Holborn ex change. The tandem exchange will act as the link ; between the two systems. a;tu> will be the clearing house through which the calls between the exchanges employ ing the different systems of telephony will be worked Work on the tandem ex change is proceeding satisfactorily, and it is expected that it will be ready to operate by the time the first automat" exchange iii opened The tandem e>, change wiljl be provided with a large number of junction lines, and. though it will cease to function when the auto matic system is completed, it is expected that it will continue to be used as a junction.