Brechner, Claude H., 1887- [from old catalog] · Boston, New York [etc.] Allyn and Bacon · leaf 177
Figure 161. — Photo-graph of ElectricDoorbell. … Figure 162. — Wiring Diagram ofTelegraph Sounder. When a current is sent through the coils C, C by attach-ing a battery at A and B, these coiJs become magnets andpull the soft iron bar down until it strikes the screw E, THE TELEGRAPH SYSTEM 167
Physics
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