The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 47
he external appearance of the PostOffice form of this transmitter is indicated in Figure 23. A new Deckert transmitter works admirably and leaves but little to bedesired, but after it has been in continuous use for some time, say threeor four months, its efficiency becomes much impaired, due to… … Figure 24. Hunnings cone transmitter, is certainly one of the best long distancetransmitters in the market. The National Telephone Company arefitting these transmitters in connection with their new systems, and itis hoped that this course will result in increased efficiency when speakingover long…
Telephone · Postal service
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