The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 33
y one of the telephones as when only one is joined up.It was thought that the combining of two receivers in one would result indouble the volume of sound. This was not the case, however, and thisand many kindred forms of receiver have now disappeared from the regionof practical telephony. The Ader… … Figure 8. the poles of which terminate in soft iron cores round which two coilsC and Ci are wound. Above the diaphragm D is placed a circular ringof iron B B^, the object of which is to concentrate the magnetic field.This ring is termed the surexcHateur (over exciter). The term is asomewhat awkward…
Telephone · Postal service
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