The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 149
a second receiver should be usedto exclude the noise, or a silence cabinet constructed in whichto place the instrument. If the wall vibrates it will giverise to noise in the transmitter, unless the latter is isolatedby being suspended on flexible springs of some kind. Having marked the position of…
Telephone
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