Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 488
re the coin, after being dropped,closed a succession of electrical contacts, which, acting through theprimary of the induction coil at the subscribers station, caused aseries of buzzes which may be distinguished by the operator. In Fig. 340 is shown a public pay station, manufactured by…
Telephone
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