Twentieth century manual of railway and commercial telegraphy (1905)
Meyer, Frederic Louis, b. 1875 · Chicago, New York, Rand, McNally & Company · leaf 33
hat line. In case of a through wire, which does notterminate at the office, it is sometimes necessary touse an intermediate battery, which is connected totwo rows of discs, one to the positive and the otherto the negative pole. The spring-]*ack is used in establishing the con-nection of instruments… … Fig. 22. metallic sides separated by a piece of hard rubber,witli a cord attached, containing two wires con-nected to the metallic sides, is inserted in any ofthe si)ring-jacks on the board. The insertion ofihe plug raises a spring lever, thereby breaking themetallic connections between the jaws of…
Telegraph
Internet Archive · Northeastern University Library · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer02inte-167-74.webp)
![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer03inte-400-251.webp)
