Telegraphy and how to learn it; with brief chapters on elementary science, embracing various kinds of electricity, electrical measurements, thermo-frictional electricty, batteries, magnets and magnetism (1901)
Frederic, Wilson. [from old catalog] · Chicago, The Henneberry co · leaf 36
a magnet. We know howit can pick up bits of iron and steel. By theaid of a small instrument, we may makea pair of small mag-nets, and study theiractions and laws. Take an insulatedwire, wind twenty ormore turns around a rodof well-annealed iron 10cm. long and about 1cm. in diameter, andclose the… … 34 TELEGRAPHY. to end, always in the same direction, andnot rubbing back and forth. Repeat theoperation with an iron wire of the same size;both the wire and the steel are attracted bythe electro-magnet, but the iron wire morestrongly. Observe that both, while in con-tact with the electro-magnet,…
Telegraph
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