Improvements in or connected with Telephones.
Year: 1892

page_text: Date of Application, 19th July, 1892-Accepted, 20th Aug., 1892
COMPLETE SPECIFICATION.
Improvements in or connected with Telephones.
I, WILHELM DECKERT, of Favoritenstrasse 34, Vienna, in the Empire of
Austria, Manufacturer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
My invention relates to telephones and especially to the signalling apparatus
used in connection therewith.
In the accompanying drawing
Figure 1 is a view of a telephone having signalling apparatus of the kind to
which my invention relates, and
Figure 2 is a diagram representing two of such telephones in an electric
circuit.
Figures 3 and 4 are views illustrating my invention.
In experimenting with carbon-point microphones a new property of the latter
was discovered, cideliret, that when excited by a current of air or by sound waves
and the diaphragm of a magneto-telephone is held opposite the diaphragm of the
microphone at a distance of say from one to five centimetres, a singing sound is
produced.
In carrying out the experiment a microphone inserted in a circuit was excited
by a pneumatic arrangement, such as indicated by the letters b, Figure 1,
although it was found that it could be excited by sound waves otherwise pro-
duced as for instance by a small whistle or trumpet, or even by the human voice.
Also the telephone receiver was placed either by hand or by a mechanical
arrangement opposite the sound funnel or mouthpiece of the microphone and from
When now the
one to five centimetres away from it, as shown in Figure 1.
ball was compressed to excite the microphone the receiver gave out a sharp
singing sound, the pitch of which was dependent upon the diameter, the strength,
and the tension of the diaphragm of the receiver and this sound continued so
long as the receiver was held in front of the microphone and the battery current
continued to pass.
Figure 4 shows an arrangement of two telephone stations in an electric circuit.
If station A wishes to call up station B the receiver R at station A is taken
off the hook of the contact T whereupon the lever a makes contact ate and the
current from the battery KZ passes through the primary coil of the induction
coil J and also through the microphone. The receiver R is then held opposite the
microphone in the manner described above and a stream of air directed on to
the diaphragm of the latter as also described. As the result of the excitation of
the microphone so caused, there is produced as previously described a singing sound
from the receiver of station B.
The object of my invention is to augment the sounds produced as hereinbefore
described and to this end it consists in interposing between the transmitter and
receiver at the sending station a hollow cylinder of soft material such as wood,
paper or india rubber, Figure 3, or in simply placing a tube or funnel of such
material upon either the microphone or the receiver as shown in Figure 3 and in
applying to the receiver of the receiving station a similar tube.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manuer the same is to be performed I declare that what I
claim is :-
In telephonic apparatus, the employment of a hollow cylinder, tube or funnel
of manor wood india rubber or other soft material in combination with either the

page_text: microphone transmitter or the receiver substantially as, and for the purposes,
described.
Dated the 19th day of July 1892.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.