Twentieth century manual of railway and commercial telegraphy (1905)
Meyer, Frederic Louis, b. 1875 · Chicago, New York, Rand, McNally & Company · leaf 20
the meaning of insulation — Where abody is separated from surrounding objects in sucha manner that it neither receives-nor imparts elec-tricity. A body is insulated by being surroundedand supported by non-conductors. MAIN^UAL OF TELEGRAPHY. 17 LESSON II. Electro-Magnetism. Electro-magnetism is that… … Magnetized Iron Bar. When the current is passing through a circuit,spirally coiling around a soft iron bar, the barbecomes an electro-magnet. The separate turns ofwire must not touch each other on the iron bar, asthis would cause a short circuit through which thecurrent would pass. The wire must be…
Telegraph
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