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 69
spressed against the paper. The groove allows a slight lineto be thus embossed upon the moving paper, its length beingat the will of the operator. 5. What is the relay magnet? As the current on a line of more than 20 or 30 miles be-comes too feeble to work the register, it is passed through apair… … It is made of veryfine wire (30 to 36)very long and veryclosely wound. Thearmature in front ofthe helices carries anupright lever. OneRelay Magnet. electrode of the local battery enters this lever, the other, after passing the registerenters the frame F which has a platinum point at P. Whenthe…
Telegraph
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