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The telephone system of the British post office. A practical handbook (1901)

Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 69

An illustration from The telephone system of the British post office. A practical handbook, 1901, leaf 69 — oden diaphragm is covered by the topboard of the instrument. In the centre of this board a hole is cut, and abrass tube carrying a china mouthpiece is fixed. This mouthpiece con-centrates the sounds of the voice, bringing them more forcibly uponthe transmitter than if the diaphragm were left open.… … instruments in use by the Post Office today. A much neater and morecompact Gower-Bell telephone was designed, and this instrument is knownas the Post Office Telephone. It is considerably smaller than theordinary form, measuring 7 inches by 5 inches and projecting 6 inches.The diaphragm is stained…

Telephone · Postal service

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