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distant signal, which he will then put to “danger.” Between this distant signal and Station B there may be a sharp curve, in which case the signalman will not put his distant signal to “danger” until the train has arrived in sight, if he have no other means of ascertaining that it is approaching. Therefore, the train may have passed the distant signal something like half a mile before the signal is put to “danger.” Now, after it left Station A, some mishap may have occurred to the engine, thereby causing its progress to be very slow. Should the express arrive at the former station ten minutes afterwards, it will be allowed to go on with the “all-right” signal (as the signalman will consider ten minutes sufficient for the stopping train to reach Station B and shunt for the express to pass). There may be a goods train waiting to follow, either from a branch line or from a siding, which will be allowed to do so; thus there will be the stopping train, the express, and the goods train, following one another between Stations A and B. Now, in consequence of the slow speed of the first train, it may arrive in sight of the signalman at Station B just as the express is passing his distant signal, and by the time that signal is put to “danger” the express may be past it. The engine-driver, as a matter of course, rushes on at full speed round this curve, to find the station signal dead against him, and the stopping train standing at the station, or shunting into the siding for him to pass—a collision of course ensuing. Or the slow train may come to a dead stop half-way between the two stations, and before the guard has had time to go back a sufficient distance to save the express, it may be upon him, particularly if the weather should be dull or foggy. Perhaps, again, before the guard of the express, in his turn, gets far back, the goods train may smash into it. That many accidents occur under these circumstances is well known to railway companies, if not to the travelling public. Nothing but the “block” system of telegraph will prevent such accidents; and the great pressure of traffic upon our railways at the present time has made it absolutely necessary that this system should be established throughout the whole length of our