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 62
OF ELECTRO-MAGNETISM. 41 2. What is the arrangement of the wires? The apparatus for secondary currents is exactly the sameas for electro-magnetic currents except that a small helix con-nected with a Bunsen element takes the place of a magnet,as in Fig. 29, P is the primary helix and I the… … 3. What is characteristic of this current? The secondary current is far more intense than the primarybut depends for its existence on a constant movement of theprimary helix, or else a constancy varying power of the bat-tery. 4. What arrangement will give a strong secondary current? Let the primary…
Telegraph
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