The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 76
ngingfrom the centre of a horizontally-stretched membrane or diaphragmand just dipping b^low the surface ofacidulated water. The wire and thewater formed part of a circuit con-taining a receiver and a battery.On speaking to the membrane,its vibrations would cause the ex-tent of contact between the…
Telephone
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![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten07unit-147-116.webp)
