FIG. 12.
FIG. 13.
As the trains when going at a considerable speed cannot be suddenly stopped, it is necessary to have signals placed in certain conspicuous positions, that the engine driver may begin to stop the train (when necessary) in time; this he effects by what is called a “break,” a contrivance by which two pieces of wood are made (by turning a screw) to grasp firmly each of a pair of wheels, and so prevent them turning round, this produces so much friction against the trams that (after the steam is turned off) the onward motion of the train is soon stopped. The signals are of three kinds generally, a red flag to indicate danger, a green one to caution, and a white one to show that the way is clear; these are (on most occasions) held by a man and waved to and fro to attract attention, but there are however a great many occasions for fixed signals, as at stations and bends in the line where the engine driver can only see a short distance ahead; these fixed signals consist of tall posts placed where they can be seen at a considerable distance. These posts have an arrangement at the top consisting of a lamp with a “bull’s-eye” or lens at each side pointing up and down the line, and a pair of arms capable of being let down into the post, raised at right angles with it, or into a position midway between the post and a right angle (as shown in [figs. 11] and [12]). One side of each arm is painted red, the other white, one arm serving for a signal up the line and the other down; attached to the joint of each arm, close to the post, are two iron frames each holding a piece of colored glass, one red the other green, and so arranged that when the arm is at right angles to the post, the red glass is before the lamp and when the arm is let half way down the green glass comes in front of the lamp ([fig. 13]), thus the same action serves both for day and night signals. When the arm showing the red side projects in a horizontal direction, it indicates (in the day) “danger,” and so does the red light at night; when the arm is let down half way, it shows that caution is required, and the green glass then before the lamp shows the same signal at night; when the arm is let quite down out of sight, it shows safety, and so does the white light of the lamp thus freed from both screens of colored glass.
FIG. 14.
Each engine is provided with a whistle ([fig. 14)] blown by steam turned on from the boiler, which is used as a signal at any particular time, especially in tunnels or when there is a fog; there is also an arrangement by which each engine presses on a lever at the side of the tram as it passes, and causes a bell to ring at the station, to announce its approach, when about a quarter of a mile off. In some cases, as in foggy weather, when the usual signals cannot be seen, a packet of fulminating powder is placed on the rail, and this being exploded by the wheel of the engine as it passes over it, gives notice of its approach, &c. There are other signals, but these are the chief.
ELECTRIC TELEGRAPHS.
