IMPROVEMENTS IN SPEAKING TELEPHONES, AND IN APPARATUS CONNECTED THEREWITH
Year: 1878

page_text: LETTERS PATENT to Joshua Franklin Bailey, of New York City, in the United
States of America, at present residing at Charing Cross, in the County of
Middlesex, for the Invention of IMPROVEMENTS IN SPEAKING TELEPHONES,
AND IN APPARATUS CONNECTED THEREWITH." A communication from abroad
by George May Phelps, of New York City, in the United States of America.
PROVISIONAL SPECIFICATION left by the said Joshua Franklin Bailey at
the Office of the Commissioners of Patents on the 2nd May 1878.
JOSHUA FRANKLIN BAILEY, of New York City, in the United States of America,
"IMPROVEMENTS
at present residing at Charing Cross, in the County of Middlesex.
IN SPEAKING TELEPHONES, AND IN APPARATUS CONNECTED THEREWITH." [A
communication from abroad by George May Phelps, of New York City, in the
United States of America.]
This Invention has for its object improvements in speaking telephones, and in
apparatus connected therewith.
A very efficient telephonic receiving and transmitting instrument is formed in
the following manner :-A straight or flat permanent magnet is provided at each
end with a bobbin of fine insulated wire surrounding a soft iron core.
The corcs
are magnetised by contact with the magnet, and the magnet is fixed against a slab
of vulcanite or other material serving as the frame of the instrument. The bobbins
are received into holes bored through the slab, the thickness of which corresponds
to the length of the bobbins.
In front of the bobbins a thin iron plate is arranged; it is held between two
sheets of thick soft paper or felt forming pads, and the whole is sbut in between the
face of the vulcanite slab and a cover of the same material, which is attached by
screws. Circular openings are cut in the pads opposite the bobbins, and so in these
positions two separate areas of the iron plate are left free to vibrate, but the pads
CD R1

page_text: prevent the vibrations extending to the frame of the instrument or to the other
parts of the plate.
In place of a single sheet of thin metal separated by the pads into different
vibrating areas two thin iron discs or diaphragms similarly held between pads may
be employed. Each disc or diaphragm or vibrating area is thus contained in a
vocalising chamber or cavity, and the rear wall of this chamber or cavity is parallel
and closely approximated to the surface of the diaphragm or vibrating plate, an
arrangement which has an important influence on the articulation of the
instrument.
A funnel-like mouthpiece is let into the cover of the instrument, and two
passages lead from it in opposite directions into the vocalising chambers, where
they terminate in face of the centres of the diaphragms or vibrating areas of the
plate; or in place of this arrangement four bobbins may be employed, surrounding
four cores magnetised by a cruciform magnet, or by two magnets. For each bobbin
there will be a corresponding vocalising chamber, with which the mouthpiece will
communicate, or the vocalising chambers may communicate the one with the other,
the mouthpiece having but one passage from it to the centre of one of these
chambers.
The magnet is held in its place by screws in such manner as to facilitate the
accurate adjustment of the distance between the ends of the cores and the face of
the plate or diaphragms. Springs are inserted beneath the magnet into holes in
the vulcanite slab, and as the screws press the magnet forward the springs are
.compressed. The slab receives a back piece which covers and conceals the magnet
and parts connected with it.
In connection with these telephones a box is provided containing a call bell and
a magneto-electric apparatus for working the call bells. Two telephones such as
described above are connected with the box by flexible conductors; one of these
telephones is intended to be used in receiving, and the other in transmitting.
When out of use the telephones are received into holders at the sides of the box,
and in connection with one of the holders is a button, which is pressed in by the
telephone when in the holder, and which serves to put the call bell in circuit and
the telephones out of circuit. There is also another button to be depressed by the
finger when it is desired to call another station, it puts the magneto-electric
machine into circuit, and the armature of the machine being at the same time
rotated currents pass into the line which actuate the call bells.
In some cases in place of employing the same or similar telephonic instruments
for transmitting and for receiving, a transmitter of the following construction is
substituted-It consists of two thin iron discs or diaphragms, held in the manner
already described, but parallel the one to the other, and they may advantageously
be of larger size than the discs, diaphragms, or vibrating areas of the plate of the
receiving instrument already described. Between these a passage leading from a
mouthpiece passes inwards towards the centre, where it enters the chambers cor-
respondinding to vocalising chambers in the instrument previously described.
Opposite the centres of the discs or diaphragms, and on the outer sides of them,
are two bobbins of insulated wire surrounding soft iron cores. The cores are
magnetised by contact with the poles of a large horse-shoe or curved magnet which
spans the discs and intervening parts. The cores are fixed to the poles of the
magnet by screws and lock nuts in such a manner as admits of the adjustment
of the cores close up to the discs, leaving just the clearance required for the
proper working of the instrument.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Joshua Franklin Bailey in the Great Seal Patent Office on the
1st November 1878.
JOSHUA FRANKLIN BAILEY, of New York City, in the United States of America,
at present residing at Charing Cross, in the County of Middlesex. "IMPROVEMENTS
IN SPEAKING TELEPHONES, AND IN APPARATUS CONNECTED THEREWITH." (A
communication from abroad by George May Phelps, of New York City, in the
United States of America.)
This Invention has for its object improvements in speaking telephones, and in
apparatus connected therewith.
A very efficient telephonic receiving and transmitting instrument is formed in
the following manner:-/
-A straight or flat permanent magnet is provided at each
end with a bobbin of fine insulated wire surrounding a soft iron core.
The cores
are magnetised by contact with the magnet, and the magnet is fixed against a slab
of vulcanite or other material serving as the frame of the instrument. The bobbins
are received into holes bored through the slab, the thickness of which corresponds
to the length of the bobbins.
In front of the bobbins a thin iron plate is arranged; it is held between two
sheets of thick soft paper or felt forming pads, and the whole is shut in between the
face of the vulcanite slab and a cover of the same material, which is attached by
screws. Circular openings are cut in the pads opposite the bobbins, and so in these
positions two separate areas of the iron plate are left free to vibrate, but the pads
prevent the vibrations extending to the frame of the instrument or to the other
parts of the plate.
In place of a single sheet of thin metal separated by the pads into different
vibrating areas two thin iron discs or diaphragms similarly held between pads
may be employed. Each disc, or diaphragm, or vibrating area is thus contained in
a vocalizing chamber or cavity, and the rear wall of the chamber or cavity is
parallel and closely approximated to the surface of the diaphragm or vibrating
plate, an arrangement which has an important influence on the articulation of the
instrument.
A funnel-like mouthpiece is let into the cover of the instrument, and two
passages lead from it in opposite directions into the vocalizing chambers, where
they terminate in face of the centres of the diaphragms or vibrating areas of the
plate; or in place of this arrangement four bobbins may be employed surrounding
four cores magnetised by a cruciform magnet or by two magnets. For each bobbin
there will be a corresponding vocalizing chamber, with which the mouthpiece will
communicate; or the vocalising chambers may communicate the one with the other,
the mouthpiece having but one passage from it to the centre of one of these
chambers.
The magnet is held in its place by screws in such manner as to facilitate the
accurate adjustment of the distance between the ends of the cores and the face of
the plate or diaphragms; springs are inserted beneath the magnet into holes in the
vulcanite slab, and as the screws press the magnet forward the springs are com-
pressed. The slab receives a back piece, which covers and conceals the magnet and
parts connected with it.
In connection with these telephones a box is provided containing a call bell and
a magneto-electric apparatus for working the call bells. Two telephones, such as
described above, are connected with the box by flexible conductors; one of these
telephones is intended to be used in receiving, and the other in transmitting.
When out of use the telephones are received into holders at the sides of the box,
and in connection with one of the holders is a button, which is pressed in by the
telephone when in the holder, and which serves to put the call bell in circuit and the
telephones out of circuit; there is also another button to be depressed by the finger

page_text: when it is desired to call another station, it puts the magneto-electric machine into
circuit, and the armature of the machine being at the same time rotated currents
pass into the line which actuate the call bells.
In some cases in place of employing the same or similar telephonic instruments
for transmitting and for receiving, a transmitter of the following construction is
substituted-It consists of two thin iron discs or diaphragms, held in the manner
already described, but parallel the one to the other, and they may advantageously
be of larger size than the discs, diaphragms, or vibrating areas of the plate of the
receiving instrument already described. Between these a passage leading from a
mouthpiece passes inwards towards the centre where it enters the chambers cor-
responding to vocalizing chambers in the instrument previously described.
Opposite the centres of the discs or diaphragins, and on the outer sides of them,
are two bobbins of insulated wire surrounding the soft iron cores.
The cores are
magnetised by contact with the poles of a large horse-shoe or curved magnet
which spans the discs and intervening parts. The cores are fixed to the poles of
the magnet by screws and lock nuts in such a manner as admits of the adjustment
of the cores close up to the discs, leaving just the clearance required for the proper
working of the instrument.
In order that the said Invention may be most fully understood and readily
carried into effect, I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a front view of a speaking telephone constructed according to this
Invention; Figure 2 is a vertical transverse section of the same; and Figure 3 is
a cross section taken in the plane of the dotted line x, in Figure 2.
The working parts of the instrument are enclosed within a hollow shell or case
A, which may be constructed of hard rubber, wood, or any other suitable material,
and may be provided with a suitable handle C.
A recess is formed within the case A, in which is placed a permanent magnet M,
which forms a yoke to the soft iron cores e, e, which are enveloped in helices E, E,
of insulated wire, the whole arrangement being precisely similar to that of an
ordinary horse-shoe electro-magnet with very short cores, except that the yoke end
instead of being of soft iron is of steel, and permanently magnetised, having its
north and south poles at n and 8 respectively.
The cores c, e, of this magnet are thus rendered permanently magnetic by
induction.
The helices E, E, are received into holes formed for them in the centre slab of
the case A, and the poles of the cores e, e, project into a shallow circular chamber
formed within the case A, the depth of which is just equal to the combined thick-
ness of the inductive plate D and the dampers F, G, between which the latter is
firmly clamped when the case A is put together.
The inductive plate D is shewn in Figure 2, in which Figure one half of it to the
right of the vertical centre line has been removed in order to exhibit the parts
beneath it.
A section of the plate D is also shown in Figure 3, the dampers F and G, between
which the plate D is clamped, are composed of thick soft paper, felt, or other
equivalent substance, and are each in the form of a flat disc, as seen at F, in Figure
2, but with a circular opening opposite each pole of the magnet. The effect of this
mode of construction is that when the plate D is compressed between the dampers
F and G the only portion of it capable of being thrown into vibrations are those
which are comprised within the area of the circular openings in the dampers, and
thus the plate D is virtually converted into two circular vibrating diaphragms d, d,
(see Figures 2 and 3).
The mouth-piece B has two conical tubes or passages b, b, leading from it, by
which the sonorous vibrations entering the mouth-picce are simultaneously
concentrated upon the two vibrating diaphragms d and d.

page_text: As the helices E, E, are both placed in or connected with the same electric
circuit, the ends of the wires being attached to the binding screws L, L, for
making connection with the line in the usual manner, it will be obvious that the
useful effect produced will be nearly or quite double that of the ordinary arrange-
ment, in which a single diaphragm and helix are employed, and by which only one
pole of the permanent magnet is utilized.
The distance between the poles of the magnet and the diaphragm may be
adjusted by means of simple screws acting to compress the flat spring m in a
manner well understood.
It is obvious that the principle of construction here adopted may be carried still
further if found desirable, for example, the permanent magnet M may be made in
the form of a cross having two north and two south poles, and provided with four
helices and four diaphragms, all of which will act in concert, and will reinforce the
action of each other, and even a greater number may be employed if desirable
without departing in the least from the principle of the Invention.
It is also obvious that separate plates might be employed for the separate
diaphragm instead of making use of a single plate sub-divided into distinct areas
of vibration by compression between dampers as berein-before described, but the use
of a single plate produces equally good results, and materially simplifies the
construction and adjustment of the instrument.
The helices or coils E, E, may be connected in series or in multiple arc between
the binding screws L and L, whichever may be advisable in any particular
instance.
Figure 4 is a transverse section of a telephone constructed according to this
Invention, but with two separate diaphragms.
The case of the instrument is formed in three parts; there is the central slab A,
the front plate B, and the back plate C.
D, D, are the diaphragms, they are applied to the face of the central slab or to
moveable rings lent into this face, and to keep them in their places until the front
plate is put on the small turn buttons or pegs E, E, are employed.
F, F, are rings of soft paper or other suitable material serving as dampers, as
already explained.
A¹, A¹, are loose rings of vulcanite, which may be employed to support the
diaphragms, they are let into recesses in the slab A, and the coil springs A", A", (of
which there are six to each rim) maintain an even pressure upon the edges of the
diaphragms.
A front view of the slab A, with the diaphragms D, D, in their places, is shown
at Figure 5; and Figure 6 is a back view of the same.
G is a permanent magnet applied to the back of the slab A, and secured by the
screws H, H; coiled springs are inserted beneath the magnet into holes at I, I, in
the slab, so that an adjustment of the position of the magnet can be obtained by
turning the screws H, H.
K, K, are soft iron cores or pole pieces attached by screws to the magnet, and
magnetised by contact with it; the cores are surrounded by the helices of fine
insulated wire L, L, which are received into holes formed to receive them in the
slab A.
M is a flexible cord containing the insulated wires by which the telephone is
connected in circuit.
Screws received into the holes N, N, connect together the parts A, B, and C of
the case; the front plate B is hollowed out to form the vocalizing chambers for the
two diaphragms, and in this case these chambers communicate the one with the
other by three passages formed between them, whilst the mouth-piece B' opens
into one of the chambers opposite the centre of the diaphragm.
In both of the telephones already described the vocalizing chambers containing
the vibrating diaphragms are made with their rear walls parallel, or nearly so, to
the surface of the diaphragms, and with as little space between them as possible,

page_text: whereby the confusion and indistinctness of the sounds produced by the vibrations
set up in the confined body of air in the rear of the diaphragm are avoided. This
part of the Invention is applicable also to telephones of other forms; thus Figure 7
is a longitudinal section of a telephonic instrument embodying this improvement,
and Figure 8 is a transverse section taken in the plane of the line d¹³, d", in
Figure 7.
The instrument shown in the Drawing is adapted to be used either for the
transmission or the reception of articulate or other sounds, and in its general con-
struction and arrangement does not differ materially from those heretofore used for
the same purpose.
The body of the instrument A may be composed of wood, vulcanized rubber, or
other convenient and suitable material. It is tubular in form, and is provided
with a solid head or flange a, as shown in the Figure, at one end upon which is
screwed a cap B. The latter is provided with a conical or funnel-shaped aperture b
passing through it from the outside, and opening into a shallow circular vocalizing
chamber formed in the face of the cup which contains the vibrating plate or
diaphragin D. This diaphragm is simply a thin elastic disc, preferably of iron or
steel It is placed with its centre in close proximity to the extremity of the core
of the helix E, which core is attached to or may form a constituent part of the per-
manent magnet F. The distance between the end of the core of the helix E and
the diaphragm D is adjustable by means of the nut g, which may be turned upon
the screw by means of a suitable key. The screw f being fixed in the end of
the permanent magnet F, the turning of the nut g in one direction or the other
serves to effect the necessary adjustment, while the pressure of the coil spring k
takes up any lost motion which may arise from looseness of the moveable parts.
The wires e, e, which form the extremities of the helix E terminate in binding
screws h, h, for the attachment of the conducting wires of the telegraph line. The
vibrating plate or diaphragm D has dampers d, d', interposed between the edge of
the diaphragm and the body of the instrument. These dampers are placed one on
each side of the diaphragm, and are made in the form of a flat ring, as shown at d³,
in Figure 8. By the addition of these dampers the clearness of articulation is
materially increased.
The walls of the vocalizing chamber which contains the vibrating diaphragm D
are made parallel to the surfaces of the diaphragm, or as nearly so as possible. The
space between the rear surface of this diaphragm D and the wall of the vocalizing
chamber which faces it is only just sufficient to admit of its free vibration. This
method of construction also greatly improves the articulation of the instrument, as
in telephones heretofore constructed the presence in the rear of the diaphragm of a
body of confined air of sufficient extent to be capable of being thrown into
vibrations, which are reflected back against the diaphragm, tends to render the
Bounds confused and indistinct. This interference is entirely avoided by the
arrangement here described, as the body of air is to small to admit of this action
taking place to an injurious extent.
Figure 9 is a front elevation, with a portion of the case removed, of a complete
telephonic instrument provided with magneto-electric call apparatus and bell.
This instrument also contains a transmitting telephone having two parallel
diaphragms, the mouth-piece communicating with chambers corresponding to the
vocalising chambers of the other telephones, being between the diaphragms.
Figure 10 is an horizontal section taken on the line 1, 1, in Figure 9; this section
passes through the middle of the transmitting telephone.
N and S are the poles of a bent magnet, they carry the adjustable pole pieces or
cores A, A, of soft iron, which are surrounded with the helices B, B; C, C, are
diaphragms of thin sheet iron in close proximity to the ends of the cores A, A.
The diaphragms C, C, are held in a frame of vulcanite or other suitable material
between dampers of soft paper, C₁, C¹, being clamping rings, which screw into
recesses in the central part of the frame, and so clamp the edges of the diaphragms.

page_text: Cavities corresponding to the vocalizing cavities of the telephones already described
are hollowed out in the central part of the frame, and a passage communicating
with the mouth-piece D passes to the centre of each cavity.
E shows the receiving telephone of the form already described in respect to
Figures 4, 5, and 6; when out of use it is held in a fork F fixed to the side of the
instrument. A front view of the fork F is shown at Figure 11, the mouth-piece of
the telephone enters between its prongs. In connection with this fork there is a
button Ġ, which is pressed inwards by the telephone when the same is in its place.
The button G acts upon a compound spring H, seen in Figure 12 (which is a
vertical section); and the button when pressed in moves the spring H from ono
contact to another, causing both the receiving and the transmitting telephones to
be placed out of circuit, whilst the bell coils are connected up in readiness to act
whenever a call may come from a distant station.
The call bell arrangement consists of four helices I, I, of covered wire wound
upon bobbins surrounding soft iron cores, which are coupled together in pairs, and
so arranged that on the passage of a current through the coils the ends of the coils
facing each other assume opposite polarities. Between these cores there is mounted
upon a pivot K the curved permanent magnet L, to which is attached the
hammer M; when the maguet L is caused to oscillate by the passage of alternating
currents in the circuit it strikes upon the two bells N, N,
The magneto-electric arrangement by means of which the bells at distant
stations are called into action consists of a large permanent magnet O, having
slightly raised pole pieces, into close proximity to which the soft iron armatures
P, P, come as they revolve. The armatures P are mounted in a frame of brass Q,
and this frame is carried upon an axis R, which can be rapidly rotated by means
of a pinion upon it in gear with the spur wheel S, which is upon the same axis
with the crank handle T. The armatures P as they rotate also pass in close
proximity to the ends of the soft iron cores contained in the helices of covered
wire U, and so by induction from the permanent magnet the cores are magnetized,
and as the armatures are carried round a rapid reversal of the polarity of the cores
takes place. This reversal of polarity causes a corresponding alternation of currents
or shocks to pass into the circuit of which the helices U form part, and by these
currents or shocks the call bells are actuated.
In order to introduce the helices U, U, into the circuit it is necessary to press in
the button marked with the letter C upon the left-hand side of the instrument, and
this is done at the same time that the handle T is turned whenever it is desired to
call a distant station.
V is a switch, by means of which the entire instrument can at pleasure be put
out of circuit.
W, W, are arresters, intended to prevent injury to the instrument from atmo-
spheric electricity; they consist of metallic surfaces, separated and insulated the one
from the other by paraffined paper, but electricity of high tension will be able to
pass from the one to the other.
Figure 13 shows a diagram of the electrical connections of the instruments.
Having thus described the nature of the said Invention, and the manner of per-
forming the same, I would have it understood that I claim,-
First. In a telephonic instrument two or more magnetic cores, whose enveloping
helices or coils are placed in the circuit of one and the same line wire, two or more
vibrating diaphragms in the same plane, and a single mouth-piece, when combined,
arranged, and operating substantially as specified.
Second. In a telephonic instrument, a diaphragm or vibrating plate in com-
bination with dampers placed on each side of said diaphragm and between it and
the supporting frame, substantially as and for the purpose specified.
Third. In a telephonic instrument a single induction plate sub-divided into two
or more separate and distinct areas of vibration in combination with two or more
magnetic cores, and two or more helices or coils, substantially as specified.
Fourth. In a telephonic instrument, a diaphragm or vibrating plate in com-

page_text: bination with a vocalizing chamber, the rear wall of which has its surface parallel,
or nearly so, to the surface of the said plate and closely approximating thereto,
substantially as and for the purpose specified.
Fifth. In a telephonic instrument, the means of holding the vibrating diaphragm
by a rigid ring pressed up to it by springs, substantially as described.
Sixth. In a transmitting telephonic instrument, two parallel vibrating dia-
phragms, with a mouth-piece communicating with chambers between the
diaphragms and magnetised cores surrounded with helices of covered wire on the
other or outer sides of the diaphragins, substantially as described.
Seventh. The telephonic instrument, substantially as described and shown in the
Drawings at Figures 1, 2, and 3, and at Figures 4, 5, and 6, and at Figure 10,
respectively.
Eighth. The combined telephonic instrument, substantially as shown and
described in respect of Figure 9 of the Drawings.
In witness whereof, I, the said Joshua Franklin Bailey, have hereunto set
my hand and seal, this Seventh day of October, in the year of our Lord
One thousand eight hundred and seventy-eight.
T T RAILEY (70)