Up to the year 1903 all the circuits in the Metropolitan District worked directly into the Central Telegraph Office, and it was essential for a telegram handed in, say, at Shepherd's Bush for delivery at Leytonstone to be signalled to the Central Office, transcribed there, circulated to the Leytonstone circuit, and transmitted from there. This necessitated a number of handlings at the Central Office. On the 5th January 1903, however, a system of through switching was inaugurated, and re-transmission obviated, so that now all that has to be done is for the office of origin to be switched through at the Central Office to the delivery office, and the telegram from one office to the other is signalled direct. The system of inter-communication has been very successful, and has not only greatly facilitated the transmission of this class of traffic, but has effected considerably economy in staff, stationery, &c. Direct switching of Metropolitan offices on to working sets in the provincial galleries has also been established. This enables telegrams to be received therein for onward transmission to provincial offices and _vice versâ_, so doing away with the greater portion of the local tubing and circulation which was necessary when all Metropolitan telegrams were received at the Central Telegraph Office on one floor only. Recently two concentrator switches have been established in the “H” and “I” Divisions on the fourth floor, and the wires connecting a large number of offices within a limited distance of London have been led thereto. The arrangement is as follows. Assuming Hatfield has a telegram with destination Leeds, the Central Office is called. This call is indicated on the concentrator by a glow light, and the board operator plugs the sending office through to one of the adjacent working sets of apparatus, where the telegram is received, circulated to the Leeds circuit, and transmitted. This system, by obviating separate apparatus and staff for each circuit, has resulted in considerable economy. On the closing of a large number of the less important wires at night, and on Sundays, it is essential for reasons of economy that the circuits then open should not extend over so large an area as at busy times. They are therefore grouped together in small sections, the provincial offices on the third, and the Metropolitan on the fourth floor. The current by which the whole of the circuits are worked at the Central Telegraph Office is generated at the Blackfriars Power Station, and conveyed by mains to the basement of the building, where the accumulators are charged, and the current distributed from these to the circuits.