Telegraph engineering : a manual for practicing telegraph engineers and engineering students (1922)
Hausmann, Erich, 1886- · New York : D. Van Nostrand Company · leaf 243
the lenses for use incase of lamp failures. Colored glass disks supported invertical sHding frames move in front of the lamp aperturesby means of compressed air, the valves being controlled byelectric track circuits (§ 5). The block signal used in thePennsylvania Railroad Tubes under the Hudson and… … Fig. 2. remains lighted and serves as a fixed signal. Similarsignals with an additional lower lamp are used as inter-locking signals. At C is shown a type of signal for daylightservice used by the Indianapolis, Columbus & Southern RAILWAY SIGNAL SYSTEMS 229 Traction Company and by other…
Telegraph
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