St. John, Thomas M. (Thomas Matthew), b. 1865 · New York, T. M. St. John · leaf 169
fg- =5;- .scriber that his call has been received and is havingattention. Fig. 254 shows another form of call box, the handlebeing moved around to the call desired. As it springsback to the original position, an interrupted currentpasses through the box to the central station, causing abell to tap…
Electricity
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