REPORT OF MR. ROBERT B. LINES.
441
It only remains to devise a simple code of signals by strokes, in order to convey to the man in charge at B the necessary intelligence from A or C, and vice versa. The difference in tone of the bells indicates to the signal-man from which side the train is approaching. The number of strokes, and their combination, may inform him of the character of the train, whether freight or passenger, and of the company to which it belongs, in case the track is occupied by two or more companies. The agent is thus given from a distance all the information which is usually conveyed from the train itself on its near approach, by means of different colored flags, lights, etc. He has, therefore, ample time to make all necessary preparations, and on the passage of the train, signals its coming in like manner to his neighbor.
A system like this requires, as will be seen, the closest attention on the part of the signal-man; and it is usual to include in the code a sign of acknowledgment, without receiving which the signal is not regarded as complete by the sender. The direct action of the magnet upon the bell- hainmer, -which constitutes the simplicity of the above apparatus, practically limits the size of the bell employed to that of an ordinary office or dining-room call-bell. When it is necessary to sound a larger bell to attract the attention of a distant attendant, machinery must be introduced, in which electricity operates, not as the direct motive-power, but as an agent to release a mechanical force strong enough to produce the desired result. One of the best and most generally employed systems of this class is that of Leopolder, which is in use on the Nordbahn and other Austrian railways, and on the Northern Railway of Italy from Turin to Venice.
I am indebted to Mr. Leopolder, and to the Allgemeine Telegraphenbau Gesellschaft of Vienna, of which company lie is a member, for a drawing of his apparatus.
The system is operated by opening instead of closing the circuit. When the apparatus is in its normal position the circuit is closed. The wires of the magnet are connected, one to the neighboring signal-station and battery, and the . other to the ground. When the circuit is thrown open the current ceases to act on the magnet, and the armature, being
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