The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 595
an be so reduced thata telephone connected in a branch circuit of a single-wire linewould remain quite silent while telegraph messages were pass-ing. As the telephonic speaking current will not affect thetelegraph instruments, it was thus possible to work bothtelephone and telegraph on the same… … CH fill- Fig. 512.—Telephonic Speech Relay. Cooper Hewitts MercuryVapour-Lamp System circuits for trunk-line working by the British Post Office asdescribed on page 490 of Chapter XXX. By making the telephone return through a second telegraphline fitted in a similar manner (at both ends of course),…
Telephone
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