The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 30
ails are not very efficient as a transmitter, but such sounds as the tickingof a clock and the pitch of a note are reproduced, but the timbre is not.Professor Hughes experimented with various substances, but finally foundthat carbon acted far better than any other substance. The most commonform of… … Figure 7. is perfectly reproduced by this instrument, notwithstanding its simple andprimitive look. The question now arises—Why should carbon behave somuch better than iron ? Shelford Bidwell investigated this subject, andcame to the conclusion that the effect was not solely due to the improve-ment…
Telephone · Postal service
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