The Propagation of Electric Currents in Telephone and Telegraph Conductors

The Propagation of Electric Currents in Telephone and Telegraph Conductors

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 edition. Excerpt: ...occupied in the transmission of a signal varies as the square of the length of the cable for cables of equal capacity and resistance per unit of length. The curve of arrival can be actually drawn by such a receiving instrument as the syphon recorder. 5. The Transmission of Telegraphic Signals aIongaCable.--We have next to consider the mode of making, and the effect of transmission along the cable on telegraphic signals.. The alphabetic code usually employed in cable telegraphy is the International Morse Alphabet, according to which each FIG. 5.--Syphon Recorder for Submarine Cable working as made by H. Tinsley & Co. letter of the alphabet is denoted by one or more intermittent applications of a constant potential battery to the sending end of the cable, such application being made by a key which connects the cable to the battery for a certain short interval of time. The battery of voltaic cells used has its centre connected to the earth, and a key is employed which connects either one or other terminal of the battery to the sending end of the cable and therefore raises it either to a positive potential--V or lowers it to a negative potential--V. r In signalling over land lines by hand-made signals the alphabetic signals are composed of short and long signals called respectively a dot and a dash. Thus the letter A is represented by a dot followed by a dash ( ). The dot is made by connecting the sending end of the line for a short interval of time with one terminal of a battery. This is then removed and-after an equal space of time connected again for a period about three times as long to form the dash. The currents into line are thus always in the same direction, but vary in duration. " In the case of cable signalling the currents...show more

Product details

  • Paperback | 88 pages
  • 189 x 246 x 5mm | 172g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236793870
  • 9781236793874