E/MJ : engineering and mining journal . ted to a lighting or power circuit, and do not re-qpire a separate low-voltage battery. When someone who may be anywhere in the plantis desired, the telephone operator simply sounds thisparticular mans call, whereupon he comes to the near- •Abstract from a paper presented before the Rochester (N. T.)Section of the American Institute of Electl-ical Engineers, Apr. est telephone, and reports, and the operator then con-nects him with the person at the other end. A specialcode-calling automatic instrument has been developedfor this purpose. The operator mere
E/MJ : engineering and mining journal . ted to a lighting or power circuit, and do not re-qpire a separate low-voltage battery. When someone who may be anywhere in the plantis desired, the telephone operator simply sounds thisparticular mans call, whereupon he comes to the near- •Abstract from a paper presented before the Rochester (N. T.)Section of the American Institute of Electl-ical Engineers, Apr. est telephone, and reports, and the operator then con-nects him with the person at the other end. A specialcode-calling automatic instrument has been developedfor this purpose. The operator merely sets the desiredpersons-code number on a dial and pulls a lever. Acontact-making mechanism is thereby set in motion,which closes the electric circuit and operates the codesignals throughout the plant the required number oftimes ( three times) and it stops automatically. A further application of loud electric horns in in-dustrial plants is for extensions to telephone ordinary telephone ringer is not loud enough in. apparatus for using the electric signal horn many shops when the foreman is away from his this case, a relay is connected in parallel with or inplace of the telephone ringer, and when it is actuatedit closes a secondary circuit, which causes an electrichorn to sound. This call should be a single blast, todistinguish it from code calls. A modern coal mine may have miles of passages androoms underground, so that the superintendent and hisassistants have to cover an extensive area. A systemof powerful horns installed throughout the mine andconnected to a code-calling instrument outside the minewould instantly convey any call, and the superintendentor whoever is called would come to the nearest telephoneand report to the operator. A further improvement of this system might consistin providing the superintendent, the foremen, the elec-trician and others with portable telephones, which couldbe connected to the line wires at any point. This isp
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectmineralindustries
