Year: 1886

page_text: Date of Application, 6th Mar., 1886.
Complete Left, 2nd Dec., 1886.
Complete Accepted, 5th Jan., 1887.
I, JOHN STUART, of 112 New Bond Street in the County of Middlesex, Gentleman,
do hereby declare the nature of this Invention, to be as follows:-
This Invention relates to improvements in telephones and it consists essentially in
the employment of two free vibrating membranes acting in combination with a magnet
and coils arranged as hereinafter explained. This improved telephone, which is
capable of being used either as a transmitter or as a receiver, is provided with a
cylindrical box or case of copper or other suitable material made in two parts screwed
together at the middle so as to support a magnet which passes through notches or
Two insulating blocks,
recesses provided for its reception in the sides of the case.
attached by screws to the limbs of the magnet, connect the communications of the
coils with the external conductors. The magnet employed is preferably in the shape
of a stirrup and may be composed of one or a number of plates according to the
magnetic power required. This magnet acts at the centre of the telephone upon two
diaphragms at once or simultaneously the said diaphragms being arranged on opposite
sides of the poles.
On the extremities of the magnet at the centre of the case there are four or other
suitable number of bobbins or wire coils arranged in pairs on each pole the coils of
each pair being separated by the thickness of the magnet. Each pair of bobbins is
fixed on the same core of soft iron, or the cores may be made in two pieces screwed
end to end in the same hole in the inagnet.
Immediately facing the coils on the two opposite sides of the box or case of the
telephone there are provided free vibrating membranes which are covered and acted

page_text: on or excited by plates or disks of sheet iron perforated at the centre to facilitate the
passage of the sound and arranged in proximity to the diaphragms being separated
from the latter by means of rings or washers of paper or the like.
When speaking in front of two telephones at once it is found that the power of the
sounds transmitted is considerably increased. In order to utilize this effect two
similar telephones constructed as hereinbefore described are combined in one apparatus
by means of a suitable case or tube provided at the side with a trumpet shaped mouth-
piece common to both telephones. This case or tube is of such a form as to enable
the sounds produced at the mouthpiece to be deflected against the centres of the
vibrating membranes of both telephones simultaneously.
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, W.C.,
Agent for the said John Stuart.

page_text: Improvements in Telephones.
I, JOHN STUART of 112 New Bond Street in the County of Middlesex Gentleman
do hereby declare the nature of this Invention which has been communicated to me
from abroad by Jules Hutinet and Pierre Felix both of 20 Rue de Chaillot Paris
in the Republic of France and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:―
This Invention relates to Improvements in Telephones and it consists essentially in
the employment of two free vibrating membranes or diaphragms acting in combination
with a magnet and coil arranged as hereinafter explained. And in order that this
Invention may be fully explained I shall now proceed more particularly to describe
the same and for that purpose shall refer to the several figures on the annexed sheets
of drawings the same letters of reference indicating corresponding parts in all the
figures. Figure one of the accompany Drawings represents a transverse section and
Figure 2 a plan partly in section of a Telephone constructed according to this
Invention. Figures 3 and 4 are details representing modified forms of the magnet
and the remaining figures (5 to 16) illustrate various modifications and combinations
of the apparatus as hereinafter described.
This improved telephone which is capable of being used either as a transmitter or
as a receiver is provided with a cylindrical box or case of copper brass or other suit-
able material made in two parts P P screwed together at the middle so as to support
and retain in position a magnet a which passes through notches or recesses provided
for its reception in the sides of the case at b. Two insulating blocks i¹ attached
by screws to the limbs of the magnet connect the coils or bobbins hereinafter referred
to with external wires or conductors not shewn in the drawing.
The magnet employed is preferably in the shape of a stirrup (Figure 1) and may
be composed of one or of a number of plates of any suitable size according to the
magnetic power required. The external part for example may be wider than the
internal part as indicated at a' in figure 3 in place of being of the same width as in
the arrangement illustrated in Figures 1 and 2.
In all telephones constructed according to this Invention this magnet acts at the
centre of the telephone upon two diaphragms simultaneously the said diaphragms
being arranged on opposite sides of the poles.
In the arrangement illustrated in figure 1 each extremity or pole of the magnet is
provided with a pair of bobbins e the coils or bobbins of each pair being separated by
the thickness of the magnet. Each pair of bobbins may be fixed on one core n of
soft iron passing through the corresponding pole or extremity of the magnet, but it
is more convenient to provide each coil or bobbin with a separate or independent core
screwed into the pole of the magnet. The number of coils shewn in the drawing is
not essential and may be increased or diminished, if preferred. For example, in place
of the flattened cores, represented in the plan, Figure 2, round cores may be employed,
as illustrated in Figure 4, and four bobbins may be provided at cach pole. The cores
are preferably made in two pieces, screwed end to end, into the poles of magnet,
so as to provide each magnet with an independent core.

page_text: Trimediately facing the coils on the two opposite sides of the box or case of the
telephone, Figure 1. there are provided free vibrating membranes er diaphragms dift
which are covered and acted on or excited by plates or dises ppl of Sheet iron, per-
forated at the centre to facilitate the passage of the sound and arranged in close
proximity to the diaphragms d, being separated from the latter, by means of rings or
washers of paper or the like and secured in position by screwed covers e.
When two telephones, constructed and arranged as hereinbefore described are
combined in one instrument and means are provided for causing the sonorous vibra-
tion to impinge against the membranes of both telephones simultaneously it is found
that the power of the sounds transmitted is considerably increased. Figure 5 illus-
trates an arrangement whereby this effect can be utilized advantageously. In the
example illustrated in figure 5 two similar telephones A and B constructed as herein-
before described are combined in one apparatus by means of a case or tube m
provided at the side with a trumpet shaped mouthpiece o communicating with both
telephones. Sounds. produced in front of the mouthpiece o create vibrations in the
chamber formed by the case m between the telephones A and B and these vibrations
are deflected against the centres of the vibrating membranes in both of the said
telephones simultaneously so as to produce a powerful effect thereon.
Figure 6 represents a portion of a telephone constructed according to this invention
and provided with a flat horse shoe magnet the two poles of which pass into the ease
at the same side and figure 7 represents a section of a similar telephone having
Ushaped magnet with superposed poles. These two forms of magnet admit of
a number of magnets being arranged radially in the case as indicated in figures 8
and 9. This arrangement enables the number of bobbins or coils to be proportionally
increased and their effects are multiplied as in a magneto electric machine.
Figure 8 represents a telephone in plan provided with a number of horse shoe
magnets and figure 9 is a similar arrangement wherein U shaped magnets are
employed. In these two figures one side only of the telephone is shown the other side
which is removed in the drawing being similar as regards the internal arrangements.
The magnets represented in figures 6 to 9 act independently that is to say each pole
is provided with a separate bobbin or bobbins. The magnets illustrated in figure 6
and 7 may be made in the form of double magnets by joining two such magnets at
their poles as indicated in figures 10 and 11. Two magnets thus combined in one
are very powerful and are provided with a single pair of bobbins an upper and a
lower. The stirrup shaped magnets herein before described may be super excited in
a similar manner by coupling them together in pairs as indicated in figures 12
and 13. Figure 12 shows two such magnets with their polar extremities arranged
side by side and figure 13 represents an analogous arrangement wherein the poles are
superposed. In either case the magnets lie in a plane at right angles to the plane of
the magnet in the arrangement described with reference to figure 1 and are flattened
accordingly so as to facilitate their adjustment and render the apparatus more
convenient to handle. Circular or other magnets may be employed being con-
tained entirely within the case of the telephone but such magnets are generally too
weak to be used with good effect in this apparatus.
A very compact and efficient telephone apparatus is obtained by placing one or two
acoustic tubes in communication with the vibrating membrane on one side of the
telephone by soldering the unions or flanges of the tubes to the exciting plates pp
herein before described. Figure 14 represents a telephone with a pair of tubes t
connected to one side of the telephone being so arranged that the person using the
apparatus can speak in front of the membrane on the other side of the telephone and
apply the tubest to his ears at the same time. This arrangement of the apparatus is
equivalent to three separate telephones the intensity of the sound is in no way
diminished but on the other hand the resistance in the circuit is considerably reduced
there being only a third of the number of coils in action. A very powerful telephonic
apparatus is obtained by using two of the improved telephones connected together by
a common case or tube m forming an intermediate chamber as hercin before described
with reference to figure 5 and providing an acoustic tube on the outer sides of each of

page_text: the outer membranes as illustrated in figure 15. Figure 16 represents another
arrangement wherein only one telephone is employed the intermediate chamber being
dispensed with and the mouthpiece o is attached to the side of the case and caused to
communicate directly with the space between the two vibrating membranes. In this
case a piece of some very light fabric (wool silk or the like) is attached to the inner
side of the vibrating membrane in order to prevent condensation of the breath thereon.
Having now particularly described and ascertained the nature of this Invention
and in what manner the same is to be performed I declare that what I claim is
First A telephone having two membranes or diaphragms vibrating freely and in
unison under the influence of a magnet or magnets whose poles are situated centrally
between the said membranes or diaphragms in the interior of the box or case of the
telephone substantially as hereinbefore described and illustrated in the accompanying
drawings.
Second A telephone having two vibrating membranes or diaphragms in com-
bination with exciting discs of sheet iron arranged in proximity to the said vibrating
membranes or diaphragms substantially as hereinbefore described with reference to
Figure 1 of the accompanying drawings.
Third A telephone having two vibrating membranes or diaphragms in combina-
tion with a stirrup shaped magnet made in one piece or built up with a number of
plates substantially as hereinbefore described with reference to Figures 1 to 4 of the
accompanying drawings.
Fourth In a telephone provided with two vibrating membranes or diaphragms
as hereinbefore set forth. The employment of bobbins coupled together in pairs and
fixed inversely or on opposite sides of the same poles of the magnet for the purpose
of acting simultaneously upon both the vibrating membranes or diaphragms sub-
stantially as herein before described.
Fifth A telephone constituted by two pairs of vibrating membranes or diaphragms
in combination with an intermediate chamber provided with a mouth piece substantially
as hereinbefore described and illustrated in figure 5 of the accompanying drawings.
Sixth-In combination with two vibrating membranes or diaphragms arranged
and operating as hereinbefore set forth the several forms arrangements and combina-
tions of magnets substantially as hereinbefore described with reference to figures 6
to 12 of the accompanying drawings.
Seventh A telephone having two vibrating membranes or diaphragms and a
magnet combined and operating as hereinbefore set forth in combination with a box
or case carrying the membranes or diaphragms and made in two parts capable of
being screwed together in such a manner as to fix the magnet in position between
the said membranes or diaphragms substantially as hereinbefore described and
illustrated in the accompanying drawing.