Abstract
AT an ordinary or manual telephone exchange, as is generally known, the subscribers' lines terminate on “jacks,” and are put through to each other by means of “plugs” and flexible conductors. The jacks, mounted on a suitable surface, form a “switchboard,” and it is the business of the exchange operator to make the necessary connections and to sever them at the proper time, to answer calling subscribers and to ring up wanted ones. Large modern exchanges are worked on the common-battery plan; that is, no batteries whatever are placed at the subscribers' offices, but a large single battery is installed at the exchange, and this supplies all the current for speaking and signalling. The switchboard is of the “multiple” type. All the subscribers are brought to each division or section of the complete board; that is all the subscribers' jacks in the entire exchange are repeated or multipled at each section, the latter forming a kind of unit of area representing the maximum reach of an operator. Every subscriber is thus within the reach of every operator. A simple “busy” test is arranged, so that before making a connection it can instantly be seen whether the required subscriber is free or already engaged at some other section. This grouping of the jacks, or “multiple” proper, is used only for ringing up and connecting to wanted subscribers. I n addition, each operator has a certain number of subscribers brought to other—“answering”—jacks, placed in her immediate vicinity, and it is on these that calls from subscribers are received. At the subscriber's end everything is arranged with a view to simplicity. The signalling is automatic; that is, the subscriber has simply to lift his receiver and the exchange is called automatically, and when the conversation is finished the replacing of the receiver upon its hook advises the operator that the connection is to be severed.
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CROTCH, A. The Automatic Telephone Exchange . Nature 87, 486–489 (1911). https://doi.org/10.1038/087486a0
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DOI: https://doi.org/10.1038/087486a0