Electro-Telegraphy

Electro-Telegraphy

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1876 edition. Excerpt: ...the trouble would be useless. 128. If it be required to prevent any but the proper station from receiving the signals the arrangements must be altered. If A wishes to send a private message to D, the connections will be thus arranged. The spring E at station D is connected through the coil to earth, and stations E and any below are thereby cut off. At stations B and C the current will be prevented passing through the needle coils by an arrangement available at need by which two points-Kme at which the coil begins, and another connected with the line terminal below--are connected by a kind of bridge of 64 STATION CONNECTIONS. copper or brass, which offers so good a passage for the current that, practically, the whole of it passes over, avoiding the coil. 129. A little consideration of the foregoing will make it easy to understand how any number of stations in a circuit can communicate with each other, and the changes that can be made. For example, if, in the above circuit, D wishes to communicate with stations below, but not with those above, he will "put on earth" against C, the next above. This means that he will connect to the earth-plate the end of the line coming in from C, thus cutting off the upper section of the circuit, and will put the further end of the needle coil to earth also. But this is seldom required to be done. 130. The plan of connections within an intermediate station may be briefly stated. The line comes in from above and from below at two separate points; to each end is soldered the end of a "lead," consisting of a strand of two or more copper wires twisted and insulated by gutta-percha or india-rubber. These leads may be of any length, and, whether short or long, will be fastened at any desired point of...show more

Product details

  • Paperback | 38 pages
  • 189 x 246 x 2mm | 86g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236555511
  • 9781236555519