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 63
htymiles of the finest copper, insulated wire. The basement isfilled with many square feet of tin foil between insulatingsheets of oiled silk. 3. What is the use of the tin foil layers? These have the effect of absorbing the extra current whichis a disturbing force. 4. At what points does the… … THE ELECTRIC TELEGRAPH. 43 5. How large a battery is required? With a secondary helix of fifteen miles of wire and a bat-tery of eight Bunsen cells most beautiful and brilliant effectsare produced. 6. How is the circuit opened and closed? The interruption of the current is often made by a…
Telegraph
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