Telegraphy, by W.H. Preece and J. Sivewright. 3rd [sic] ed

action adjustment apparatus armature arrangement brass cable carbon causes cell circuit conductor connected contact points copper sulphate cores covered wire creosoted current flows Daniell cells Daniell's battery deflection depressed direction disc disconnected distance distant station dots duplex earth-wire ebonite effect electricity electromagnet employed England fault fixed galvanometer gauge gutta percha hole inches induced inserted instrument insulation iron wire joint latter leakage Leclanché cell length lever line current line wire local battery magnet means messages metallic mile Morse motion moved needle number of wires ordinary paper piece pipes placed pole porous portion position potential principle purpose receiving relay reverse rheostat screw sending sent short circuit shown in fig side signals soft iron soldered sonorous vibrations Sounder spring strength switch tangent galvanometer telegraph terminal terminal station test-box th real tion tongue transmitter tube vary Wheatstone bridge words per minute zinc plate zinc sulphate