Twentieth century manual of railway and commercial telegraphy (1905)
Meyer, Frederic Louis, b. 1875 · Chicago, New York, Rand, McNally & Company · leaf 23
ed another piece of the samemetal. One being insulated from the other, the currentcan not j)ass between them, except while the lever ispressed down, bringing together the two platinumpoints, which are in reality the two ends of thewire. A spring is employed to keep these twopoints separated. How is… … The Relay. Of what does the relay consist—Of a bar orarmature so ar-ranged as to befree to movewhen acted uponby an electro-magnet, andwhicli, whenmoved, closes a ^^■- ^^■ local battery circuit through the sounder connectedwith the relay. Is there any communication of electricity be-tween the local…
Telegraph
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