IMPROVEMENTS IN TELEPHONIC APPARATUS
Year: 1882

page_text: LETTERS PATENT to Henry Harris Lake of the firm of Haseltine Lako
& Co., Patent Agents Southampton Buildings London, for an Invention of
"IMPROVEMENTS IN TELEPHONIC APPARATUS " Communicated to him from
abroad by Charles Adams Randall of the City and State of New York
United States of America, Electrician
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at the
Office of the Commissioners of Patents on the 27th November 1882.
"
HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, London, "IMPROVEMENTS IN TELEPHONIC APPARATUS
[A communication to him from abroad by Charles Adams Randall of the City and
State of New York United States of America, Electrician]
This Invention relates generally to that class of telephonic instruments in which
the two poles of a magnet act upon each other to produce the vibrations which
result in the production of sound and to induce the currents of electricity required
for sound transmission.
It also relates to automatic devices by which the receiving telephone and
transmitter at a station are placed in and out of circuit.
The first part of my Invention has for its object to produce an instrument
without the ordinary membrane or diaphragm and which will yet readily respond
to and reproduce and transmit all the tones of the human voice.
This part of my Invention consists in employing an electro magnet, one pole of
which is placed in contact with a wall of the casing or boxing of the instrument,
which latter may be of any suitable material such as wood, india-rubber, glass or
the like. The vibrations or changes of the magnetic pole in contact with the
casing of the instrument due to the variations of electrical current will be communi-
cated to the wall of the casing and by it be propogated through the air and
rendered audible thus giving the instrument the character of a telephonic receiver.
When used as a transmitter sounds uttered in proximity to the wall of the casing
with which the magnet pole is in contact will cause vibrations in the said wall and
TD 031

page_text: +
these vibrations will be communicated to the magnet pole causing it to disturb the
magnetic field in such manner as to induce in the helix of the magnet currents or
variations of current which cause the reproduction of the sounds by a similar or
other receiving instrument in circuit through a line wire.
The details and special organization which I use in carrying out the first part of
my Invention I will now proceed to particularly describe.
The case of the instrument may be made of any suitable and usual non-
conducting material, and is provided with the handle portion which is to be grasped
by the hand of the operator or user. The case may be made in any suitable
manner providing a chamber which has an open side into which the magnet may be
After the
inserted, and secured by screws or in any other suitable manner.
magnet has been properly arranged the side of the case is closed by a wall composed
of a resonant side piece and flange the latter being screwed to the case.
The polar end of the leg of the magnet which is fastened to the case is bent and
elongated at a right angle and the laterally extended portion carries the ordinary
coil or helix which is connected to the line wire and secondary helix of the
induction coil of a transmitter in the usual manner. The end of the opposite leg
of the magnet is arranged in close proximity to the tip of the polar extension and
is in contact with the resonant side piece of the casing. The operation will be
readily understood and it will be obvious that the instrument may be used either
as a transmitter or a receiver.
The resonant piece is preferably formed with a concave face and with its
surrounding flange presents the appearance of an ordinary mouth-piece or car-picco
It is also preferably made a little thinner at its portion which contacts with the leg
of the magnet than at any other portion and preferably thinner than the flange.
No particular configuration of the resonant side. wall in contact with the leg of
the magnet is essential, however as said wall may be perfectly-plain at its surfaces
and round, oval or angular in edgewise contour. The concave face however serves
a useful purpose in concentrating the sound and indicating the most advantageous
point directly opposite which to speak, and at which to place the ear.
The magnet may have two helices mounted on its polar extension and these
helices may be connected to different main circuits respectively as will be readily
understood.
I may employ a magnet having both of its legs bent at right angles and extended
toward each other, each of the polar extensions thus formed carrying a helix and
these helices may be included in different main circuits. This magnet may be
applied in a similar manner to that first described one of the legs being placed in
contact with the resonant side wall.
I may employ a ring magnet provided with a helix on each pole; or a horse
shoe permanent magnet with soft iron pole pieces and a helix on one pole of the
magnet only or a compound horse shoe magnet similarly equipped.
Any of these modifications of the magnet may be substituted in the casing for
the first named magnet.
In my improved instrument as now described there is no aperture in the casing
and no membrane or diaphragm in a telephonic sense, is employed...
I also provide a telephonic instrument furnished with still another modification
of the sound transmitting and reproducing devices. In this construction I use a
permanent magnet of approximately horse-shoe shape, the ends of the legs being
opposite each other and though differing in form they have about equal quantities
of metal so that about the same magnetic force is exerted by each pole. In fact
any two opposite points of the different legs of the magnet have about the same
cross sectional area, although they may differ in shape of section. One leg of the
magnet is designed to be practically rigid and therefore has its metal massed to
give approximately a square cross-section but the other leg has its polar end
Hattened and made quite thin within an annular margin or frame-like portion this
thin portion serving as a diaphragm or vibrator. To operate this vibrator I
provide the rigid.leg with an adjustable soft. iron pole piece which is arranged. in

page_text: an aperture formed in the leg and held in place by a screw, said pole piece carrying
a helix and being provided with an adjusting handle extending through the casing.
The annular frame-like portion of the leg is provided with suitable screw holes and
is screwed to the wall of the casing.
In the front wall of the casing an aperture is formed concentric with the thin
portion or diaphragm of the inagnet and in this aperture is screwed a mouth and ear
piece having a central opening opposite the central portion of said diaphragm in
the usual manner. At the end of the casing is an aperture closed by a screw plug.
By removing the plug access may be had to the screw for loosening the pole piece
to allow of its adjustment.
It will be obvious that when the helix is properly connected in circuit in the
manner usual in telephone systems the instrument may be used as both transmitter
and receiver.
In my improved instrument a cross section through any part of the diaphragm
or vibrator and the annular frame of which it forms a part will show an area
approximately equal to that of the cross section of the opposite point of the
opposite leg, and therefore the magnetic force of the poles will be practically equal
and the actuating pole will operate the diaphragin with great vigor.
According to another part of my Invention I provide automatic devices for
placing the receiver and transmitter in and out of circuit. In order to ensure the
placing of the transmitter primary coil in circuit at a station whenever the
receiver is taken in the hand and to break the transmitter battery circuit whenever
the receiver is laid down or relinquished I employ in one form of my Invention
dovices located in and upon the handle portion of the receiver. A switch pivotted
within the handle of the instrument is arranged to make simultaneous contact
with contact points but is held normally out of contact with said points by means
of an elastic arm secured on the outside of the handle and connected with said
switch at one end by means of an arm. When the operator grasps the handle of
the instrument be compresses the clastic arm causing the switch to swing on its
pivot and form metallic connections between the contact points and thus complote
the circuit which includes the primary helix of the transmitter induction coil.
When the operator has finished and relinquishes the receiver the transmitter
battery circuit is immediately broken by the recoiling of the elastic arm. By this
arrangement of devices I am enabled to absolutely assure the proper closing and
opening of the circuit whenever the receiver is taken up and relinquished, an
advantage obvious to those familiar with the subject. This result does not depend
on the placing of the receiver in any particular position or place after use upon
the independent operation of any switch mechanism. Suitable call or signal
mechanism will of course be placed at each station.
According to a modification of my Invention the devices which cut out the call
or signal and throw in the transmitter or vice versa depend for their action upon
the position of the receiver.
My circuit opening and closing devices are not dependent upon auy special form
of telephone but may be applied to various kinds of such instruments. To tho
inner surface of the back wall of the chamber in which the magnet is located a
closed tube formed of non-conducting material is secured longitudinally. This tube
contains a conductor of electricity which is free to move therein by gravity
according to the position of the receiver. This conductor may be mercury,
acidulated water, a ball or balls of metal or any other suitable material though
I prefer mercury. The wires enter the telephone handle passing from a suitable
stud or binding post to a contact point in one end of the tube. From another
contact in the same end of the chamber a wire extends to transmitter and
connection is thence made through the transmitter and battery to ground. Thus
the moving conductor rests at the lower end of the tube and completes the circuit
between the contact points. A branch wire passes to a contact at the opposite end
of the tube and a wire leads from a similar contact to the call apparatus and ground.
It is obvious now that if the telephone be placed in a reversed position the call

page_text: apparatus will be thrown into circuit and the transmitter cut out. The telephone
should be suspended from the handle supported in some suitable way in the
position last referred to when not in use, so that the call apparatus will be in
circuit. Then when the telephone is raised to the car to answer a call the
transmitter will be thrown into circuit as above described by the shifting of the
movable conductor.
The tube or chamber may be partitioned or divided in the middle with a
separate movable conductor in each compartment. Such arrangement may be
found desirable for some reasons. The operation is precisely like that above
described.
The modification now described contemplates broadly a moving or shifting
conductor always acting vertically which makes one circuit and breaks another
according to the position in which the telephone is placed and the details may
be varied without departing from the spirit of my Invention.
If for any reason more than two circuits are employed and are to be made and
broken other tubes or chambers and contact points may be used.
I may use a modified combination of devices for cutting the instrument
in and out of circuit the operation of these devices being dependent upon
the hanging of the instrument upon a hook or similar support and the
removing it therefrom. In the end of tho handle of the instrument is formed
a chamber closed at its outer end by a screw plug through the centre of
which is loosely arranged a metallic rod having one end extended into and
nearly through the chamber and the other end terminated by a shoulder and
ring outside of the plug. Through the rod inside of the chamber passes a pin and
between the pin and the plug is arranged a spiral spring surrounding the rod and
having its ends bearing against the plug and pin respectively, so that when the rod
is free it will be forced inward by the tension of the spring until its shoulder rests
against the plug but when the instrument is suspended by the ring the spring will
be compressed and the rod drawn outward until a non-conducting plate which is
set into the rod comes in contact with a metallic spring which is secured to the inner
surface of the plug and has its end bearing against the rod the non conducting
plate breaking metallic connection between the rod and said spring. The spring
forms one of the terminals of the helix, the other terminals of which is connected
directly with a binding post fixed on the plug. A similar binding post is connected
with the spiral spring and through it and the pin is in metallic connection with the
rod. The binding posts hold the separate wires of the ordinary connecting cord
which are to be connected with the line in the usual or any suitable manner. It
will be obvious that when the receiver is hung by the ring and the rod is thus so
far drawn out the non conducting plate breaks the metallic contact of the rod
and spring the circuit through the helix will be broken but so soon as the
instrument is removed from its hook for use, the spring will force the rod inward
and bring the metallic portion in contact with the other spring and thus close the
circuit through the helix. These devices may be varied without departing from
my Invention and I do not therefore limit myself to the specific construction
described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Great Seal Patent Office on the
24th May 1883.
وو
HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co, Patent Agents,
Southampton Buildings, London "IMPROVEMENTS IN TELEPHONIC APPARATUS
A communication to me from abroad by Charles Adams Randall, of the City and
State of New York, United States of America, Electrician
This invention relates generally to that class of telephonic instruments in which
the two poles of a magnet act upon each other to produce the vibrations which
result in the production of sound.
It also relates to automatic devices by which the receiving telephone and
transmitter at a station are placed in and out of circuit.
The object of the first part of this invention is to produce an instrument without
the ordinary membrane or diaphragm and which will yet readily respond to and
reproduce and transmit all the tones of the human voice, and it consists essentially
in employing an electro-magnet, one pole of which is placed in contact with a wall
of the casing or box of the instrument, which latter may be of any suitable
material such as wood, india-rubber, glass or the like. The vibrations or changes
of the magnetic pole, in contact with the casing of the instrument, due to the
variations of electrical current will be communicated to the wall of the casing and
by it be propagated through the air and rendered audible thus giving the
instrument the character of a telephonic receiver. When used as a transmitter,
sounds uttered in proximity to the wall of the casing with which the magnet pole
is in contact will cause vibrations in the said wall and these vibrations will be
communicated to the magnet pole causing it to disturb the magnetic field in such
manner as to induce in the helix of the magnet, currents or variations of current,
which cause the reproduction of the sounds by a similar or other receiving
instrument in circuit through a line wire.
The said invention is illustrated in the accompanying drawing in which
Figure 1 is a longitudinal section of an instrument constructed according to the
said invention, and designed for use especially as a receiver, this view showing,
also, in diagram, the ordinary induction coil circuits and the connections of a
transmitter at a telephonic station.
Figures 2, 3, 4, 5 and 6 illustrate modified forms of magnets which may be used
in the improved instrument.
Figures 7, 8 and 9 illustrate another modification
Figures 10, 11, 12 and 13 are views illustrating another part of this invention
and hereinafter described.
Referring to Figure 1 A is the case of the instrument which case may be made
of any suitable and usual non-conducting material, and is provided with the
handle portion A' which is to be grasped by the hand of the operator or user. The.
said case may be made in any suitable manner for providing a chamber which has
an open side as at a, into which the magnet M may be inserted, and secured by
screws 6 or in any other suitable manner. After the magnet has been properly
rranged the side of the case is closed by a wall composed of the resonant side
piece B and the flange b' the latter being screwed to the case.
1
The polar end of the leg of the magnet M which is fastened to the case is bent.
t a right angle and elongated and the laterally extended portion m carries the
rdinary coil or helix H which is connected to the line wire L and the secondary.
elix of the induction coil I of a transmitter in the usual manner. The end of the..

page_text: opposite leg M¹ of the magnet is arranged in close proximity to the tip of the polar
extension m and is in contact with the resonant side piece B of the casing. The
operation will be readily understood and it will be obvious that the instrument may
be used either as a transmitter or a receiver
The resonant piece B is preferably formed with a concave face B¹, and with its
surrounding flange b' presents the appearance of an ordinary mouth-pieco or
ear-piece. It is also preferably made a little thinner at its portion which is in
contact with the leg of the magnet, than at any other portion, and preferably
thinner than the flange b¹.
No particular configuration of the resonant side wall in contact with the leg M¹
of the magnet is essential as the said wall may be perfectly plain at its surfaces
and round, oval or angular in edgewise contour. The concave face however serves
a useful purpose in concentrating the sound and indicating the most advantageous
point directly opposite which to speak, and at which to place the ear
In Figure 2 the magnet is shown as having two helices H mounted on its polar
extension m and these helices may be connected to different main circuits
respectively as will be readily understood.
In Figure 3 a magnet is shown having both of its legs bent at right angles and
extended toward each other, each of the polar extensions thus formed carrying a
helix H and these helices may be included in different main circuits. This magnet
may be applied in a similar manner to that shown in Figure 1 one of the legs
being placed in contact with the resonant side wall, and operating in the same
manner as the magnet shown in Figure 1.
Figure 4 shows a ring magnet provided with a helix on each pole; and Figure 5
shows a horseshoe permanent magnet M2 with soft iron pole pieces m³ and a
helix H on one pole of the magnet only Figure 6 shows a compound horse-shoe
magnet similarly equipped.
Any of these modifications of the magnet may be substituted in the casing for
the magnet shown in Figure 1.
It is observed that in the improved instrument there is no aperture in the
casing, and no membrane or diaphragm, in a telephonic sense, is employed.
Figures 7, 8. and 9 illustrate a telephonic instrument furnished with still another
modification of the sound transmitting and reproducing devices. In this con-
struction I use a permanent magnet M³ of approximately horse-shoe shape, the
ends of the legs being opposite each other, and, though differing in form, they have
about equal quantities of metal, so that about the same magnetic force is exerted
by each pole. In fact, any two opposite points of the different legs of the magnet
have about the saino cross sectional area, although they may differ in shape of
section. One leg m³ of the magnet is designed to be practically rigid and therefore
has its metal massed to give approximately a square cross-section, but the other
leg m has its polar end flattened as shown at m³ and made quite thin as shown
at me, within an annular margin or frame-like portion, this portion serving as a
diaphragm or vibrator. To operate this vibrator I provide the rigid leg m³ with
an adjustable soft iron pole-piece P which is arranged in an aperture formed in the
leg, and held in place by a screw p₁ the said pole piece carrying a helix H² and
being provided with an adjusting handle p', extending through the casing A³.
The annular frame like portion m³ of the leg m' is provided with suitable scrow
holes, and is secured to the wall of the casing by screws b³, b.
In the front wall of the casing an aperture is formed concentric with the thin
portion or diaphragm me of the magnet, and in this aperture is screwed a mouth
and ear piece E having a central opening opposite the central portion of the said
diaphragm in the usual manner. At the end of the casing is an aperture closed by
a screw plug a³. By removing the plug access may be had to the screw p¹ for
loosening the pole piece P, to allow of its adjustment.
It will be obvious that when the helix H2 is properly connected in circuit in the
manner usual in telephone systems, the instrument shown in Figure 7 may be used
as both transmitter and receiver,

page_text: I am aware that it is not new to simply flatten one of the poles of a magnet to
form a diaphragm but in telephones heretofore having this feature the thin
diaphragm has not had a mass of metal as great as that of the magnet pole opposite
it, nor been formed as a part of a pole equal or nearly equal in mass to the opposite
pole, and therefore the actuating pole has been comparatively weak. In this
improved instrument a cross section through any part of the diaphragm or
vibrator and the annular frame of which it forms a part, will show an area
approximately equal to that of the cross section of the opposite point of the opposite
leg, and therefore the magnetic force of the poles will be practically equal and the
actuating pole will operate the diaphragm with great vigour
According to another part of this invention I provide automatic devices for
placing the receiver and transmitter in and out of circuit. In order to ensure the
placing of the transmitter primary coil in circuit at a station whenever the receiver
is taken in the hand, and to break the transmitter battery circuit whenever the
receiver is laid down or relinquished, I employ the devices located in and upon the
handle portion of the receiver as shown in Figure 1. A switch S, pivotted at 8
within the handle A¹ of the instrument, is arranged to make simultaneous contact
with contact points p, p, but is held normally out of contact with the said points
by means of an elastic arm S₁ secured on the outside of the handle and connected
with the said switch at one end by means of an arm 8¹. When the operator grasps
the handle of the instrument he compresses the elastic arm, causing the switch S
to swing on its pivot and form metallic connections between the contact points p, p,
and thus complete the circuit a, a, which includes the primary helix of the
transmitter induction coil I, the transmitter being indicated by T and the
transmitter battery by T². When the operator has finished and relinquishes the
receiver, the transmitter battery circuit is immediately broken by the recoiling of
the elastic arm S¹. By this arrangement of devices I am enabled to assure the
proper closing and opening of the circuit whenever the receiver is taken up and
relinquished, an advantage obvious to those familiar with the subject. This result
does not depend on the placing of the receiver in any particular position or place
after use or upon the independent operation of any switch mechanism. Suitable
call or signal mechanism will be placed at each station.
According to a modification of the said invention shown in figure 10 the devices
which cut out the call or signal and throw in the transmitter, or vice-versa, depend.
for their action upon the position of the receiver. Figures 11 and 12 are detail
views illustrating the operation of the said devices, the call or signal circuit being
completed in Figure 12 and the transmitter circuit completed in Figure 11.
The sound receiving and transmitting device ashown in Figure 10 are substantially
the same as those shown in Figure 1 and therefore need not be again described.
The circuit opening and closing devices are not dependent upon any special form of
telephone, but may be applied to various kinds of such instruments. To the inner
surface of the back wall of the chamber in which the magnet M is located, a closed
tube F formed of non-conducting material is secured longitudinally. This tube
contains an electrical conductor G which is free to move therein by gravity,
according to the position of the receiver. This conductor may be mercury,
acidulated water, a ball or balls of metal or any other suitable material though I
prefer mercury. The wires enter the telephone handle at the ground line being
shown at 1, passing from a suitable stud or binding post to a contact point at 12 in
one end of the tube. From another contact point in the same end of the chamber,
a wire 2 extends to the transmitter, and connection is thence made through the trans-
mitter and battery to ground. Thus with the telephone in the position shown in
Figure 10, the moving conductor rests at the lower end of the tube and completes
the circuit between contact points and 1. A branch wire 3 passes to a contact
piece at the opposite end of the tube and a wire 4 leads from a similar contact
piece d to the call apparatus and ground. It is obvious that if the telephone be
placed in a reversed position to that shown in Figure 1 the call apparatus will be

page_text: thrown into circuit and the transmitter cut out. The telephone should be
suspended from the handle N supported in some suitable manner in the position
last referred to when not in use, so that the call apparatus will be in circuit.
Then when the telephone is raised to the ear to answer a call the transmitter
will be thrown into circuit as above described by the shifting of the movable
conductor
In the diagram Figure 11, the telephone circuit is shown as complete and the
call cut out, as in Figure 10, while in Figure 12 the telephone is indicated as
inverted, and the call circuit is complete and the other is broken.
In the modification shown in Figure 13, the tube or chamber F1 is shown as
partitioned or divided in the middle, with a separate movable conductor in cach
compartment. Such arrangement may be found desirable for some reasons. The
operation is precisely like that above described. This modification contemplates
broadly a moving or shifting conductor always acting vertically, which makes one
circuit and breaks another according to the position in which the telephone is
placed, and the details may be varied without departing from the nature of my
invention
If for any reason more than two circuits are employed, and are to be made and
broken other tubes or chambers and contact points may be used.
In the handle of the instrument shown in Figure 7, is illustrated a modified
combination of devices for cutting the instrument. in and out of circuit, the
operation of these devices being dependent upon the hanging of the instrument
upon a hook or similar support and removing it therefrom. In the end of the
handle A of the instrument is formed a chamber a closed at its outer end by a
screw plug a, through the centre of which is loosely arranged a metallic rod B*
having one end extended into and nearly through the chamber and the other end
terminated by a shoulder 8 and ring 6 outside of the plug. Through the rod,
inside of the chamber, passes a pin 6, and between the pin and the plug a is
arranged a spiral spring 6 surrounding the rod and having its ends bearing against
the plug and pin respectively, so that when the rod is free it will be forced inward
by the tension of the spring until its shoulder rests against the plug, but when the
instrument is suspended by the ring the spring will be compressed and the rod
drawn outward until a non-conducting plate v, which is let into the rod, comes in
contact with a metallic spring which is secured to the inner surface of the
plug as and has its end bearing against the rod, the non conducting plate breaking
metallic connection between the rod and the said spring. The spring v¹ forms one
of the terminals of the helix H2; the other terminal of which, is connected directly with
a binding post p* fixed on the plug a. A similar binding post p is connected.
with the spiral spring and through it and the pin is in metallic connection
with the rod B². The binding posts ps and po hold the separate wires of the
ordinary connecting cord C, which are to be connected with the line in the usual or
any suitable manner. It will be obvious that when the receiver is hung by the
ring b³, and the rod B' is thus so far drawn out and the non-conducting plate v
breaks the metallic contact of the rod and spring v¹, the circuit through the helix H²
will be broken; but as soon as the instrument is removed from its hook for use
the spring 6 will force the rod B2 inward and bring the metallic portion in contact
with the spring v¹, and thus close the circuit through the helix H2. These devices
may be varied without departing from the nature of this invention, and I do not
therefore, limit myself to the construction shown
Having thus fully described the said invention as communicated to me by my
foreign Correspondent, and the manner of performing the same, I wish it understood
that I Claim :-
First. The combination of the casing, a bent electro-magnet, and the solid
sounding piece of the casing against which one pole of the said magnet rests,
substantially as described with reference to Figure 1 of the drawing, and for the
purpose set forth.

page_text: Second. The combination of a casing, a magnet secured therein, the helix helices
of the said magnet being connected in the main line circuit or circuits, and a solid
resonant sounding piece against which the free pole or leg of the magnet rests,
substantially as described.
Third. The combination of the casing, the magnet secured therein, the helix of
the magnet, and the solid resonant sounding piece B of the casing having the
concave mouth surface B' against the back of which the pole of the magnet rests,
substantially as described
Fourth. The combination of the casing, the magnet bent so as to bring its poles
in close proximity to each other, and the helix or helices carried by the said
magnet, substantially as set forth.
Fifth. A magnet bent so as to bring its poles in close proximity to each other, in
combination with a helix or helices carried by the said magnet.
Sixth. The combination of a telephone carrying contact terminals, the trans-
mitter circuit, a switch pivotted directly in or upon the telephone and adapted to be
worked by the grasp of the operator to make connections between the terminals,
and a device for automatically breaking the connection between the said terminals
when the telephone is laid down, substantially as set forth.
Seventh. The combination with a telephone, of a switch carried thereby and
adapted to make circuit when grasped and break circuit when released by the
hand of the operator, substantially as set forth.
Eighth. The combination of the telephone, the pivotted switch within tho
telephone, the contact points, and the elastic arm secured on the telephone, with
which arm the switch is connected and by which it is operated, substantially as set
forth.
.
Ninth. A telephone magnet having its poles arranged opposite each other, one
being practically rigid and the other vibratory or flexible, but both poles having
approximately equal mass of metal, substantially as described.
Tenth. A telephonic instrument provided with a magnet, one of the poles of
which is practically rigid and the other thinned to form a diaphragm or vibrator,
the said diaphragm being surrounded by a rigid frame which is a part of the same
pole, substantially as described.
Eleventh. A magnet having one leg rigid and provided with an adjustable pole
piece carrying a helix, as described, and the other pole flattened and thinned to
form a diaphragm and surrounding rigid frame, as set forth.
Twelfth. The combination, with the casing having the chamber a* in its handle,
and the helix, as shown in Figure 7 of the drawing, of the rod B arranged to slide
longitudinally in the said chamber and provided with the non-conducting plate, the
spring arranged to force the said rod inward and permit it to be drawn outward by
the weight of the instrument, and the spring v₁ bearing against the said rod and
forming one of the terminals of the helix, substantially as described.
Thirteenth. The combination, with the casing and the spring-controlled rod
provided with a suspending device, of devices arranged to break and close the
circuit of the instrument in accordance with the position of the said rod,
substantially as described.
Fourteenth. The combination of a telephone, the moving or shifting conductor
carried thereby, and the contact points substantially as described with reference to
Figure 10 of the drawing.
Fifteenth. The combination of a telephone, the moving or shifting conductor, the
transmitter circuit, the call circuit and their contact points, substantially as
described with reference to Figures 11 and 12 of the drawing.
Sixteenth. The combination, with a telephone receiver, of a tube or chamber
containing a shifting or moving conductor and having line and call circuit
connections located at its ends respectively, and adapted to operate only when
the tabe or chamber is in a vertical position, for the purpose set forth.
Seventeenth. A telephone having one or more tubes or chambers each divided

page_text: into separate divisions and provided with contact points at its ends, the said contact
points being connected with different circuits in pairs, each compartment of the
tube or tubes or chambers enclosing a moving or shifting conductor, substantially
as described with reference to Figure 13 of the drawing.
In witness whereof I the said Henry Harris Lake, have hereunto set my
hand and seal this Twenty fourth day of May in the year of our Lord One
thousand eight hundred and eighty three
HENRY LAKE (L.B.)