Telephones, their construction and fitting; a practical treatise on the fitting-up and maintenance of telephones and the auxiliary apparatus (1892)
Allsop, Frederick Charles · London, New York, E. & F.N. Spon · leaf 222
C/A/e A/£3 I … Three Telephone Stations all of which can communicate. The Station not speaking to No. 1 rings up on the Extersion Bell, by means of which Bell also Nob. 2 and 3, when connected together, can call the attention of No. 1. CONNECTING-UP. 193 No. 2 is unconnected with the extension bell, the…
Telephone
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