Prevention of Accidents from Collision. Curtis's Lamp Signals. - Hawkshaw's Signals and Switches. - Steam Whistle. - Taylor's Guard's Signals. - Porteous's Mouth Whistle. - Electric Telegraph - principles upon which its action depends. - Cooke and Wheatstone's two arrangements of the Electro-Magnetic Telegraph. - Professor Morse's Apparatus for preventing Collision between-Trains.
The most numerous accidents on railways, and at the same time the (generally) most disastrous in their effects, are those resulting from collision, either between two trains, or between the carriages composing one train, from an accident to the engine or leading carriages; and in the present section we propose to notice some of the means employed to guard against dangers from this cause.
Collisions on railways take place under various circumstances. It may sometimes happen that two trains, proceeding in opposite directions, are at certain parts of the road obliged to travel on the same line of rails, and should they at such time come into collision the results must be the most disastrous. Accidents of this description are however very rare, and unless at sharp curves, or in very foggy weather, could only arise from extreme heedlessness on the part of those employed on both trains. Collisions more frequently arise from a train overtaking another train, proceeding in the same direction, or from a train arriving at a station, which is unexpectedly occupied by another train. In all cases they may be said to arise from some irregularity in the working at some part of the line, and might be avoided if timely notice were given of such irregularity; and accordingly various kinds of signals are employed or have been proposed to effect this, some being produced by sounds, others being addressed to the eye, and in other cases both sound and visible signals being employed.
The figure (page 524) represents Mr. Curtis's apparatus for giving notice of the approach of a train to a station, or warning to a train that the station is occupied.
The peculiarity of the plan consists in conveying the signal a mile, or any convenient distance, from the station, with the object that the engineer may pass the signal post, and have distance and time sufficient to stop the train, before reaching the station, or place for stopping. The figure represents the apparatus for exhibiting a light.
"a is a lamp-post surmounted by a lantern of any peculiar shape, with bulls' eyes on three sides, or it may be formed of glass like a street lamp, or in any other manner. c is the lamp with reflectors behind the light in the usual way. b is a shade supported upon the vertical rods e. passing through the post and united by a joint at its lower end with the bell-crank f, to which is likewise suspended the ball or weight m. To the other end of the crank f a joint is attached, with which is connected a strong wire g, which is led like a bell-wire by proper connexions to the crab h, placed in a room of, or near, the station house. The wire, or a chain or rope united to its end, is fastened to the barrel i of the crab h which coils round the barrel. When a man turns the handle k, the barrel i is turned round by means of the pinion fixed on the handle shaft, and the barrel wheel denoted by the circle a; and the chain or rope or wire is coiled round the barrel, the wire drawn in, and the crank f made to occupy the place shown by the dotted line; and thus the vertical rod e and shade b are raised, and the light concealed. The counterbalance m is employed to keep the connecting wire g always stretched.
In places where gas is employed, a large gas burner may be substituted for the lamp, and the rod c made to communicate with a stop-cock, so that by raising or depressing the rod, the gas may be turned off or on; a small concealed jet of gas may be always burning, so as to inflame the larger jet when the rod is raised by the apparatus: thus a powerful light may be used when needed, and when not required, the gas may not be wasted. The apparatus as drawn is a night signal, or to be used when the weather is so dark that other signals cannot be seen; but for a day signal it is merely necessary to employ a post, so as to raise a vane or vanes like a telegraph, a spar, for example, fixed at the top of the lantern. When it is required to use the telegraph, a man may make the necessary and self-evident connexion between the rod e and the limb of the telegraph, which limb being made with a bell crank, when the rod e is raised, may cause the telegraph limb to lie horizontally, and when the rod e is depressed, it will stand vertically, or the apparatus may be formed double, so as to work both telegraph and lamp at once, whether by day or night
The best arrangement of this system of signals will be, to place them at the same distance asunder as the police are stationed; and instead of making a signal by a flag, upon the passage of a train, they should convey the notice of its approach to the next policeman in advance; which would advise him to look out that switches, points, and everything besides are right
By a self-evident modification of this apparatus, the engine can be made to communicate its own approach.