Theory and practice of the electric telegraph; a manual for operators and students (1875)
Churchill, Charles Henry, d. 1904. [from old catalog] · Oberlin, Ohio, Sherman & bros. · leaf 102
operate at the same time, so that the operator can alwrivsjudge how both lines are working. £. Local Circuit Changer.—1. What is the ohject of the local circuit changer? It is often important to change a set of instruments to a dif-ferent line. For example: Suppose a sounder is placed onone… … A M It In Fig. 46 M and Mare the relays S the sounder and E the register; A and Av are the local batteries; B is a small button switch, having four connecting points, numbered 1, 2, 3, 4. When the button connects 1 and 2 the relay M works the under S, and Mthe register. When it connects 3 and 4 so…
Telegraph
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