Britain at Work
A Pictorial Description of Our National Industries

WITH THE RAILWAY SIGNALMEN. 259 level, and therefore prevents a switch being moved whilst a train is passing over it; and another form of detector bar, which locks the ingress to tracks already occupied by a train. We must now say a few words about those apparatus which make the trains provide for their own safety by automatically telegraph- ing their passage through a block section. The most famous of these systems is “ Sykes’s Electric Lock and Block,” the signalman to the driver from electrically controlled machines, so arranged that it is impossible for more than one tally to be got out of two machines taken together at the same time. “Tyers’s Electric Train Tablet” Photo: Cassell & Co., Ltd. CLAPHAM JUNCTION AT NIGHT. object of which is to prevent more than one train being between two signal boxes on the same track at the same time. This is accomplished by a signalman not being able to lower the signal controlling the entrance to the block section ahead until that signal has been electrically released by the signal- man at the box in advance, who cannot so release the signal until the preceding train has passed over a rail contact in advance of his own starting signal and that signal has been put to “danger." In the signal cabin two indicators are placed, one reading either “ Line clear” or “ Line blocked,” and referring to the condition of the section ahead ; the other reading “Train on line” or “Train passed,” and referring to the section in rear. The former indicator is connected with the lock in such a manner that, when it reads “ Clear,” the lock is lifted and the lever is free ; but when it reads “ Blocked,” the lever is locked. It is thus impossible for one signalman to organise a collision. Coming to the working of single-track railways, there are several apparatus which prevent more than one train being between any two block stations at the same time, and, when no train is in the section, to admit of a train being started from either end. A staff or tablet must be carried with each train, and this form of tally can only be issued by the and the “ Electric Train Staff” are the two principal systems in vogue. In order to obviate the stoppage of a train whilst the driver and signalman exchange tallies, special apparatus are now provided so that the operation may be performed in speed. Sometimes the tablets are placed in leathern pouches and hung on rings, through which the two men respectively thrust their arms; a Scotch railway makes use of an apparatus, known as the “ snapper,” which exchanges tablets automatically on very much the same principle as the mail bags are caught up and set down in nets; and there are various forms of non-automatic “catchers” and “deliverers” placed alongside the track.