IMPROVE- MENTS IN TELEPHONES
Year: 1878

page_text: LETTERS PATENT to Carl Heinrich Siemens, of No. 12, Queen Anne's Gate,
Westminster, in the County of Middlesex, for the Invention of "IMPROVE-
MENTS IN TELEPHONES." A communication from abroad by Dr. Werner
Siemens, of Berlin, in the German Empire.
PROVISIONAL SPECIFICATION loft by the said Carl Heinrich Siemens at
the Office of the Commissioners of Patents on the 25th June 1878.
CARL HEINRICH SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in the
County of Middlesex. "IMPROVEMENTS IN TELEPHONES." [A communication from
abroad by Dr. Werner Siemens, of Berlin, in the German Empire.]
In employing a telephone for cominunicating with a distant person, it is necessary
to provide means to call his attention to the fact that a communication is about to
be addressed to him, so that he may be prepared to listen.
This Invention relates to a modification of the instrument known as Bell's
telephone, and the application to it of a sounding instrument, so as to produce an
alarin calling a listener's attention to the message about to be sent. For this
purpose the iron diaphragan of the telephone, which is advantageously made of
considerable size, is mostly covered by wood or other casing, having an aperture in
the middle for transmission of the sound pulses to or from the diaphragm, a sinall
space being left between the diaphragm and its cover, sufficient to allow for the
vibrations of the former. At the edge of this space holes are made extending out
to the exterior of the casing, so as to allow passage for pulses of air produced by
the sounding of the alarm instrument.
This instrument may be constructed as a whistle or mouth-piece containing a
close or free reed, which when not in use is attached to the telephone by a cord or
chain. When it is to be used its one end is inserted into the aperture of the
diaphragm cover, which it fits, and the mouth is applied to the other end so as to
produce the sound, the pulses of which, causing vibrations of the diaphragm of the

page_text: sending instrument, are reproduced by those of the diaphragm of the receiving
instrument.
A convenient form of free reed alarm instrument consists of a tube divided by a
longitudinal partition into two chambers, the one of which has at its end an opening
to which the mouth is applied, and the other has an open end which is directed
towards the diaphragm of the telephone. The partition has through it a slit in
which the reed is fitted.
In order to increase the noise made by the alarm, it is of advantage to provide
in the end of the alarm tube a loose haminer or ball which is free to vibrate. This
hammer touching the diaphragm is put in vibration by sounding the alarm, so as
to give a series of blows to the sending diaphragm which are reproduced by the
receiving diaphragm.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Carl Heinrich Siemens in the Great Seal Patent Office on the
23rd December 1878.
CARL HEINRICH SIEMENS, of No. 12, Queen Anne's Gate, Westminster, in the
County of Middlesex. "IMPROVEMENTS IN TELEPHONES." A communication from
abroad by Dr. Werner Siemens, of Berlin, in the German Empire.
In employing a telephone for communicating with a distant person it is necessary
to provide means to call his attention to the fact that a communication is about to
be addressed to him, so. that he may be prepared to listen.
This Invention relates to a modification of the instrument known as Bell's
telephone, and the application to it of a sounding instrument, so as to produce an
alarm calling a listener's attention to the message about to be sent. For this
purpose the iron diaphragm of the telephone, which is advantageously made of
considerable size, is mostly covered by a wood or other casing having an aperture
in the middle for transmission of the sound pulses to or from the diaphragm,
a small space being left between the diaphragm and its cover sufficient to allow
for the vibrations of the former. At the edge of this space holes are made extending
out to the exterior of the casing, so as to allow passage for pulses of air produced
by the sounding of the alarm instrument.
.
This instrument may be constructed as a whistle or mouth-piece containing a
close or free reed, which when not in use is attached to the telephone by a cord or
chain. When it is to be used its one end is inserted into the aperture of the
diaphragm cover, which it fits, and the mouth is applied to the other end, so as to
produce the sound, the pulses of which causing vibrations of the diaphragin of the
sending instrument are reproduced by those of the diaphragm of the receiving
instrument.
A convenient form of free reed alarm instrument consists of a tube divided by a
longitudinal partition into two chambers, the one of which has at its end an opening
to which the mouth is applied, and the other has an open end which is directed

page_text: towards the diaphragm of the telephone. The partition has through it a slit in
which the reed is fitted.
In order to increase the noise made by the alarm it is of advantage to provide in
the end of the alarm tube a loose hammer or ball which is free to vibrate. This
hanner touching the diaphragm, is put in vibration by sounding the alarm so as
give a series of blows to the sending diaphragm, which are reproduced by the
receiving diaphragm.
Figures and 2 shew longitudinal sections at right angles to each other of a
telephone having one arrangement of the before-described Invention applied.
thereto.
The iron diaphragm a is covered in at top by means of a casing b, having.a
central hole through which, when speaking, the vibrations are transmitted to or
from the diaphragm, but which at other times has fitted into it an alarm or whistle c.
This may be of any known construction for producing a sound by a passage through
it of pulses of air. As shown in the Drawing it consists of a casing with an
opening c¹ at top, and an internal partition, with slit containing a reed c³, so that
on blowing through the hole c¹ a sharp sound is produced, which by means of the
diaphragm is transmitted to an ordinary receiving telephone at the other end of the
circuit. In addition, the alarm has a small ball d, with a stem sliding freely through
a guide, so that the ball rests upon the diaphragm and is thus caused by its vibration
to produce a sharp rattling noise, which is also transmitted to the receiving telephone.
Small lateral channels e, e, are formed in the casing b, through which the air pulses
blown in through the alarm c escape into the open air.
The telephone is by preference constructed of a horse-shoo magnet f, with thin
polar extensions g, carrying the coils /, connected to the circuit, as described in my
former Patent, No. 4685, of 10th December 1877, the distance of the poles g from
the diaghragm, being adjustable by means of an excentric pin i, carried by the
frame j, and passing between the pins, carried by the magnet.
Having thus described the nature of the said Invention, and in what manner the
same is to be performed, as communicated to ine by my foreign correspondent, I
claim,
First. Constructing telephones with a casing or cover enclosing the iron diaphragm,
and having a hole serving both for the transmission of pulsations when speaking,
and for the reception of a sounding instrument for signalling, side passages being
formed in the said cover for the escape of air pulses, substantially as herein
described.
Second. The combination with a telephone, constructed as set forth in the
preceding claim, of a sounding instrument arranged to fit into the hole of the cover
of the diaphragm thereof, so that by sounding such instrument corresponding
pulsations are imparted to the diaphragm, substantially as herein described.
Third. The usc, in combination with apparatus constructed as set forth in the
preceding claims, for a loose hammer or ball carried by the sounding instrument,
and arranged so that when this is fitted to the telephone the hammer will rest upon
the diaphragm and will produce a noise by the vibrations imparted thereto, sub-
stantially as herein described.
In witness whereof, I, the said Carl Heinrich Siemens, have hereunto set my
hand and seal, this Twenty-first day of December, in the year of our Lord One
thousand eight hundred and seventy-eight.
CUDT THE PAT
AINA
CARL HEINRICH SIEMENS.
(L.S.)