IMPROVEMENTS IN THE METHOD OF TRANSMITTING OR REPRODUCING AND REPEATING SOUNDS BY ELECTRICITY, IN THE METHOD OF DESTROYING THE EFFECTS OF INDUCTION IN A TELEPHONIC LINE, AND IN TELEPHONIC TRANSMITTING AND REPEATING APPARATUS
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patont Agent, for an Invention of "IMPROVEMENTS
IN THE METHOD OF TRANSMITTING OR REPRODUCING AND REPEATING SOUNDS
BY ELECTRICITY, IN THE METHOD OF DESTROYING THE EFFECTS OF INDUCTION
IN A TELEPHONIC LINE, AND IN TELEPHONIC TRANSMITTING AND REPEATING
APPARATUS." A communication from abroad by George Milton Hopkins, of
Brooklyn, in the County of Kings and State of New York, United States of
America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 11th February 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN THE METHOD OF TRANSMITTING
OR REPRODUCING AND REPEATING SOUNDS BY ELECTRICITY, IN THE METHOD
OF DESTROYING THE EFFECTS OF INDUCTION IN A TELEPHONIC LINE AND IN
TELEPHONIC TRANSMITTING AND REPEATING APPARATUS." [A communication
from abroad by George Milton Hopkins, of Brooklyn, in the County of Kings
and State of New York, United States of America.]
This Invention relates to the class of instruments employed in transmitting
articulate speech, musical sounds, signals and all kinds of sounds that can be made
to produce vibratory motion in diaphragms, plates, reeds or other vibratory bodies
by the agency of electric currents.
The first part of the Invention consists essentially in a contact surface attached
to a vibratory diaphragm or other body capable of vibratory motion and a floating
electrode pressed against the contact surface by a column of liquid.
The second part of the Invention consists in a floating electrode having an
enlarged contact surface in combination with a pivoted vibrating electrode moved
by a vibratory diaphragm; the object being to obtain a perfect adaptation of one
electrode to the other, and to ensure a conducting surface sufficiently large to
convey the electric current without being injured by it.

page_text: .
The third part of the Invention consists in two sets of electrodes insulated from
each other and vibrated alternately in opposite directions; one set of electrodes
being placed in the primary telephonic circuit, and the other set in the secondary
circuit; the object being to interrupt the secondary circuit so as to break up the
effects of induction and render the induction currents and earth currents available
in transmitting over difficult and long lines.
The fourth part of the Invention relates to instruments for repeating articulate
speech from one telephone line to another so that telephonic communication may be
extended to a practically unlimited distance. The instrument by means of which
this important result is secured consists of an electro magnet connected with the
end of a telephone line and located with reference to the vibratory iron diaphragm
of a flouting electrode telephone transmitter so that the diaphragm will be vibrated
by the action of the magnet so as to enable the transmitter to repeat the telephonic
message to the second line.
I will now describe in detail the telephonic transmitter referred to under the
first head.
The diaphragm is clamped by a cap upon the top of a hollow standard fixed to a
support. To the centre of the diaphragm is attached a small metallic cup which
contains a button of ordinary hard carbon.
The diaphragm may be of metal or mica; if of inetal it may be made part of
the electrical conductor, the circuit being completed through a spring attached to
the diaphragm support and connecting with a wire running downward through the
hollow standard and its support. Inside the standard there is a glass bottle having
a long narrow neck and a rounded base which rests on an adjustable ring by which
it may be supported at any desired height in the hollow standard. The bottle is
partly filled with mercury which comes into contact with a platinum wire which
enters through the bottom of the bottle and buoys up a pencil of carbon which
passes through and is guided by the long narrow neck and is pressed lightly
against the carbon contact-surface attached to the diaphragm.
The carbon pencil is of the kind commonly used for electric lighting by
incandescence and it may be made to press against the carbon button more or less
forcibly by raising or lowering the bottle.
The pencil is prevented from slipping from the surface of the carbon button by
a short paper tube slipped over the button and projecting downward a short
distance.
Another form of contact surface consists in a small rounded button of platinum
projecting from the end of a brass screw upon which is placed a small vulcanite
cup. The brass screw passes through the diaphragm and recives a nut by which
the vulcanite cup is drawn tightly against the diaphragm and the screw is put into
electrical connection with the diaphragm.
The vulcanite cup serves to keep the carbon pencil in the proper position
relatively to the platinum contact surface.
If a mica diaphragm be used in the instrument the communication between the
spring and cup may be effected by attaching a strip of copper foil to the surface of
the diaphragm so as to be pressed by both cup and spring.
The inovable mercury bottle presents an easy means of altering the pressure of
the carbon pencil on the contact surface attached to the diaphragm, but instead of
this device may place the mercury in a tube and displace it so as to vary the
height by means of a piston or by a screw entering the tube.
Under favorable conditions a metallic electrode may be used instead of the carbon
pencil or a small electrode supported by a float of nonconducting material may be
employed. Or a spring lever may be secured to one side of the diaphragm
support and extend across the diaphragm and be provided with an adjusting
screw, the free end of the lever carrying a carbon or platinum contact surface
like that first described which is pressed by a floating pencil of carbon as herein-
before described.
This transmitter is placed in an electrical circuit in which there is a telephone

page_text: receiver or the primary wire of an induction coil, the secondary wire of which
is in circuit with one or more telephone receivers. The current passes through
the wire spring, diaphragm, carbon button, carbon pencil, the mercury contained
in the bottle and the wire extending from the bottle through the base of the
instrument.
Any sound made in the vicinity of this instrument sets its diaphragm in
vibration and by moving the contact surface interrupts the current flowing through
the electrodes.
By means of this instrument articulate speech may be clearly transmitted and
vocal and instrumental music may be sent over a line.
To facilitate the collection of sounds I attach to the cap of the diaphragm case a
flaring mouth piece which is curved so that the speaker may occupy a natural
position while using the instrument.
The chief advantage possessed by the instrument over others of its class are its
extreme sensitiveness, it being capable of transmitting articulate sounds made ten
feet or ten inches from the instrument with equal facility. It can never get out
of adjustment as no springs, weights or adjusting screws are used or required.
When it is desirable to employ a stronger electric current than will be safely
conducted by the small contact surfaces above described, I employ devices in which
the contact surfaces are very much enlarged.
According to one arrangement the diaphragm is supported in the usual way by
a mouth piece which in this instance is attached to a base piece supporting an iron
flont receptacle also an induction coil and the necessary switches. A yoke shaped
bracket is secured to the centre of the underside of the diaphragm in which
bracket is hung between centres a clip which embraces the central portion of a
short cylindrical bar of carbon. The clip turns easily on its centres so that the
carbon can swing in a vertical plane and readily adapts itself to any surface with
which it may be brought into contact.
The upper end of the iron float receptacle is of small calibre and a wooden float
rod passes loosely through it.
The lower portion of the float receptacle is enlarged to receive a quantity of
mercury by which the float rod is supported. The float rod is tubular and traversed
by a copper wire which dips in the mercury at its lower end and touches a carbon
disc secured to the upper end of the float rod or the wire is placed in electrical
communication with the carbon disc by means of a screw passing through the
centre of the carbon disc into the end of the wooden float rod and touching the
wire. The float receptacle and diaphragm are joined up in the electrical circuit
with a battery, and the primary wire of an induction coil. The secondary wire
of the coil is connected with the receiver, the ground and the line in the usual
way. The primary or battery current passes through the float receptacle and the
mercury contained therein, through the wire in the float rod, carbon disc, pivoted
carbon bar, its supporting bracket and the primary wire of the induction coil to
the battery.
When sounds are made in the vicinity of the diaphragm it is set in vibration
carrying with it the pivoted carbon bar and the bar vibrating more quickly than
the floating carbon disc interrupts the current at the point of contact between the
two carbon surfaces and produces audible effects in the receiver connected with
the secondary circuit of the induction coil. It has been found by repeated
experiments that this instrument transmits articulate speech with great clearness
and loudness and it has been determined by actual and continued trial that it will
not get out of adjustment under the usual conditions of use.
To facilitate packing the instrument for shipping or storage a rubber packing
ring is placed upon the float rod below the carbon disc. The packing ring is forced
down upon the upper end of the float receptacle by inserting a piece of cork
between the carbon electrodes.
In the transmitter thus described the diaphragm must of necessity be placed in
à horizontal position when the instrument is in use. To provide au instrument
'
•

page_text: with a vertical diaphragm I interpose between the diaphragm and the carbon bar
electrode, a right-angled lever. The diaphragm is vertical and instead of attaching
the bracket directly to the diaphragm it isformed on the horizontal arm of the right-
angle lever whose vertical arm carries an adjusting screw which bears against
the diaphragm.
The lever is fulcrumed on a spring supported by the mouth piece.
The vibrations of the vertical diaphragm are transferred to the right angled lever
which in turn transfers them to the carbon electrodes.
It is obvious that electrodes of other material than carbon may be employed.
The various metals have been used for this purpose with, in some instances, very
satisfactory results. For this reason I do not confine myself to any particular
material for the electrodes.
The float receptacle is held in a clamp so that it may be adjusted or moved up
or down.
It is well known to persons familiar with the operations of the telephone that
it often happens that the currents induced in a telephone wire by adjacent telephone
or telegraph lines are far more effective in producing soun-is in the receiving
telephone, than the legitimate source of sound and hitherto all attempts to separate
the induced currents of the line from the induction currents of the telephone
transmitter have resulted in failure from the fact that both currents are of the
same nature, and whatever tends to weaken or destroy one will also tend to
weaken or destroy the other.
This Invention obviates this difficulty by interrupting the secondary current at
every vibration of the diaphragmn of the transınitting instrument so that all currents
foreign to the telephone current may be utilized in increasing the volume of
intelligible sounds in the receiving instrument by interrupting them so as to
compel them to act in unison with the currents set up in the secondary circuit by
the telephone.
In carrying out this Invention I prefer to employ the above described telephone
transmitter in which one electrode of each set is kept in contact with the opposing
electrode by the buoyant force of a liquid but I do not confine the Invention to
transmitters of this class.
According to another arrangement two float receptacles such as last described
partly filled with mercury and insulated from each other are provided with wooden
Hoat rods supported by the buoyant force of the mercury contained in the receptacles.
Upon the upper end of these float rods there are carbon dises one disc on each
communicating with the mercury below by means of a wire passing through the
rod into the mercury.
A lever of insulating material pivoted centrally upon a standard projecting from
the bottom of the mouth-piece, carries a bracket at each end in each of which a
short carbon rod held in a clip is pivoted between centres as before. These carbon
rods are pressed by the carbon discs on the float rods.
The lever is connected by one of its ends with the diaphragm by a flexible
connection which is in electrical connection with the bracket at that end so that
when the diaphragm is vibrated the lever is oscillated on its pivot. The mouth
piece containing the diaphragm is of the usual description and is supported in any
convenient way in a fixed position in relation to the float receptacles.
The primary current of the battery passes through the primary wire of the
induction coil, the bracket connected to the diaphragm, the carbon bar pivoted in
such bracket, the carbon disc on the float rod and the mercury in the receptacle.
The primary current is interrupted at the point of contact between the pivoted
carbon bar and the carbon dise whenever the lever is oscillated. The line wire
connects with the bracket at the other end of the lever and one terminal of the
secondary wire of the induction coil communicates with the mercury in the other
float receptacle while the other terminal is grounded. A receiver is placed in the
The
secondary circuit between the induction coil and this float receptacle.
secondary current of the induction coil passes to the line through the mercury in

page_text: the receptacle, the float rod carbon disc, pivoted carbon bar, and the bracket in
which it is pivoted, and the secondary current is interrupted at the line of contact
between the pivoted carbon bar and the carbon disc on the float rod.
Whenever a sound is made in the vicinity of the diaphragm the impact of an
individual sound wave deflerts the diaphragm downward and brings the pivoted
carbon bar at that end of the lever into close contact with its carbon disc ensuring the
completion of the primary circuit, while the same movement raises the pivoted
carbon bar at the other end of the lever from its carbon disc and the secondary or
line circuit is for the instant broken. When the diaphragm retracts the action is
reversed the secondary circuit is completed at the moment the primary circuit is
interrupted. It will therefore be noticed that the stronger impulse of the
secondary current which occurs when the primary circuit is broken, has a complete
circuit to traverse, the contact between the carbon bar and disc in this circuit'
occurring at this instant.
The interruption of the main line circuit practically destroys the effects of
induction from other lines and adds volume to the intelligible sounds heard in the
receiving telephone.
In a modified form of transmitter the interrupter for the primary circuit is
substantially the same as that already described, the only essential point of
difference is that instead of using a lever the bracket in which the pivoted carbon
electrode of the primary circuit is centred is attached directly to the diaphragm
and the carbon disc forming one of the electrodes of the secondary circuit is
attached to the top of the diaphragm by an insulating medium and is connected
electrically with the secondary wire of the induction coil. The pivoted carbon
electrode is centred in a bracket as before supported by an arm directly over the
carbon dise on the diaphragm.
This arm is pivoted at its end on the mouth-piece and the line wire is connected
to it at its pivoted end. The primary current passes from the battery through the
primary of the induction coil, the carbon bar and disc of the interrupter, and the
mercury contained by the receptacle to the battery.
The secondary wire of the induction coil is grounded through the telephone
receiver and the secondary current goes to the line through the carbon disc and
bar of the interrupter and the pivoted arm by which the latter is supported, to
the line.
The primary circuit is interrupted with every upward movement of the
diaphragm at the line of contact between the carbon electrodes of its interrupter
and the secondary circuit is interrupted at every downward movement of the
diaphragm at the line of contact between the carbon electrodes of its interrupter.
The results obtained by this arrangement are substantially the same as those
obtained by the instrument last described.
I will now describe the improved telephone repeater. In carrying out this part
of the Invention 1 employ a straight bar magnet surrounded by a helix and
supported over a horizontal diaphragm. For the transmitting portion of the
repenter I use a telephone transmitter similar to that first herein-described in
which a floating electrode is pressed upward against a platinum or carbon contact
surface on the diaphragm by the buoyant force of mercury.
The first or up line wire is connected with one of the terminals of the helix, the
other terminal being grounded in the usual way. The local circuit which is
operated by the action of the magnet is through the primary wire of an induction
coil, the contact surface attached to the diaphragm, the floating electrode, the
mercury, to the battery.
The secondary wire of the induction coil is arranged and connected in the usual
way, that is, one of its terminals is connected with the second or down line and
the other is grounded. Electrical impulses sent over the up line in the usual way
affect the power of the magnet so that it alternately attracts and releases the
diaphragin and causes breaks in the local circuit at the point of contact between
the electrode attached to the diaphragm and the floating electrode.

page_text: In this way the local circuit is operated in the same manner as it would be
operated if the diaphragm were vibrated by speaking in its vicinity.
By this means impulses are set up in the induction coil which are communicated
to the second or down line.
In this manner speech may be communicated from one line to another without
material loss, permitting of the extension of telephone lines beyond the usual
working distance.
In a modified form of telephone repeater, the magnet is made hollow and formed
so as to answer the double purpose of magnet and mercury and float receptacle and
is placed below the diaphragmn. The neck of the float receptacle is made of
suitable size externally to receive the helix and internally to form a guide for the
fluating electrode. The diaphragm is of iron and carries a contact point of carbon
or platinum against which the floating electrode is pressed.
Electrical impulses sent over the first or up line wire traverse the helix and
affect the strength of the magnet so that the diaphragm is vibrated, breaking the
contact between the contact point and the floating electrode, interrupting the
primary circuit of the induction coil, whose secondary wire is connected with the
second or down line and with the ground. In this manner speech is transmitted
from one telephone line to another. The last two instruments described answer
equally as well for telephone transmitters as for repeaters.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on
the 9th August 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of
Middlesex Patent Agent. "IMPROVEMENTS IN THE METHOD OF TRANSMITTING OR
REPRODUCING AND REPEATING SOUNDS BY ELECTRICITY, IN THE METHOD OF
DESTROYING THE EFFECTS OF INDUCTION IN A TELEPHONIC LINE, AND IN
TELEPHONIC TRANSMITTING AND REPEATING APPARATUS." A communication
from abroad by George Milton Hopkins of Brooklyn in the County of Kings and
State of New York, United States of America.
This Invention relates to the class of instruments employed in transmitting
articulate speech, musical sounds, signals, and all kinds of sounds that can be made
to produce vibratory motion in diaphragms, plates, reeds, or other vibratory bodies
by the agency of electric currents.
The first part of the Invention consists essentially in a contact surface attached
to a vibratory diaphragm or other body capable of vibratory motion and a float
supported electrode pressed against the contact surface by a column of liquid. The
second part of the Invention consists in a floating electrode having an enlarged
contact surface in combination with a pivoted vibratory electrode moved by a
vibratory diaphragm, the object being to obtain a perfect adaptation of one electrode
to the other, and to secure a conducting surface sufficiently large to convey the
electric current without being injured by it. The third part of the Invention consists
in two sets of electrodes insulated from each other and vibrated alternately in
opposite directions, one set of electrodes being placed in the primary telephonic
circuit, and the other set in the secondary circuit, the object being to interrupt the
secondary circuit so as to break up the effects of induction and render the induction
currents and earth currents available in transmitting over difficult and long lines.
The fourth part of the Invention relates to instruments for repeating articulate
speech from one telephone line to another so that telephonic communication may
be extended to a practically unlimited distance. The instrument by means of which
this important result is secured, consists of an electro magnet connected with the
end of a telephone line and located with reference to the vibratory iron diaphragm
of a floating electrode telephone transmitter so that the diaphragm will be vibrated
by the action of the magnet so as to enable the transmitter to repeat the telephonic
message to the second line.
In the accompanying Drawings, Figure 1 is a vertical section of the telephone
transmitter showing the relation of the various parts. Figure 2 is a detail view
of the contact surfaces. Figure 3 is a sectional view of a transmitter employing a
lever to move the contact surface. Figure 4 is a side elevation partly in section
of a modified form of transmitter employing enlarged contact surfaces. Figure 5
is a front sectional elevation taken on line y-y in Figure 4. Figure 6 is a
sectional plan view taken on line 2-z in Figures 4 and 5 looking downward.
Figure 7 is a side elevation partly in section of a modification of the instrument
shown in Figure 4. Figure 8 is a side elevation partly in section of a telephone
transmitter employing two sets of contact surfaces or electrodes, one set being for
the primary circuit, the other set for the secondary circuit. Figure 9 is a side
sectional elevation of a modified form of double contact transmitter. Figure 10
is a side elevation partly in section of the telephone repeater for repeating from
one telephone line to another. Figure 11 is a modified form of the same.
Referring to Figure 1, the hollow standard A. is secured to a fixed support B
and has formed on its upper end a support for the diaphragm C which is clamped
in its place by the cap D. To the centre of the diaphragm is attached a disc E of
ordinary hard carbon. The diaphragm C inay be of metal or mica; if of metal.

page_text: the diaphragm may be made part of the electrical conductor, the circuit being
completed through the spring G attached to the diaphragm support and connecting
with the wire H running downward through the hollow standard A and its
support. In the standard A. there is a ring I having a stud a that projects
through a slot in the side of the standard A. and is provided with a milled nut by
which it may be fixed in any desired position. A glass bottle K having a long
narrow neck L and a rounded base, rests on the ring I and may be supported at
any desired height in the hollow standard A, A platinum wire b enters the lower
end of the bottle and is connected with the wire M, the end of which extends
through the base of the instrument. The bottle K is partly filled with mercury
which comes into contact with the platinum wire bat bottom of the bottle and
buoys up a pointed float rod N which carries on its upper end a carbon disc c
having a central conical cavity for securing the point of the float rod. The float
rod may be a conductor of electricity or it may be of wood or other light material
enclosing a wire conductor which touches the carbon disc c and dips in the
mercury in the bottle K; disc c is pressed by the float rod into light contact with
the carbon disc E attached to the diaphragm C. The force with which the float
rod N may be made to press against the carbon disc c may be varied by raising
or lowering the bottle K.
In Figure 2 is shown an enlarged view of the contact discs. If a mica
diaphragm be used in the instrument, the communication between the spring G
and carbon disc E may be effected by attaching a strip of copper foil to the
surface of the diaphragm when it will be pressed by both the carbon disc and the
spring.
The movable mercury bottle presents an easy means of altering the pressure of
the carbon pencil on the contact surface attached to the diaphragm, but instead of
this device I may place the mercury in a tube and displace it so as to vary the
height by means of a piston or by a screw entering the tube. In Figure 3 a spring
lever O is secured to one side of the diaphragm support and extends across the
diaphragm and is provided with an adjusting screw f. The free end of the lever
carries a carbon disc E like that already described in connection with Figures 1
and 2, and the surface is pressed by a disc c supported by the float rod N.
This transmitter is placed in an electrical circuit in which there is a telephone
receiver or the primary wire of an induction coil, the secondary wire of which is in
circuit with one or more telephone receivers. The current passes through the
wire H, spring G, diaphragm C, carbon discs E c, float rod N, the mercury contained
in the bottle K, and the wire M extending from the bottle through the base of the
instrument. Any sound made in the vicinity of this instrument sets its diaphragm
in vibration and by moving the contact surface interrupts the current flowing
through electrodes. By means of this instrument articulate speech may be clearly
transmitted and vocal and instrumental music may be sent over a line. To
facilitate the collection of sounds I have attached to the cap D of the diaphragm
case a flaring mouth piece which is curved so that the speaker may occupy a natural
position while using the instrument.
The chief advantage possessed by the instrument over others of its class are, its
extreme sensitiveness, it being capable of transmitting articulate sounds made
10 feet or 10 inches from the instrument with equal facility. It can never get out
of adjustment as no springs, weights, or adjusting screws are used or required.
In Figures 45 and 6 the diaphragm A¹ is supported in the usual way by the
mouth piece B¹ and the mouth piece in this instance is attached to a base piece C
supporting the iron float receptacle D¹, also the induction coil which in the present
case is represented by the diagram K' and the necessary switches which are not
shown in the Drawing. A yoke E' is secured to the centre of the diaphragm A¹
by means of a screw or otherwise and is provided with two pivotal screws a¹ a¹
which form bearings for the yoke F which embraces the central portion of a short
cylindrical bar G₁ of carbon. The yoke F turns easily on the points of the
screws a' a' so that it readily adapts itself to any surface with which it may be

page_text: brought into contact. The upper end of the iron float receptacle D' is of small
calibre fitting the wooden float rod H' loosely so that the rod may move up and
down with a minimum of friction. The lower portion of the float receptacle D'
is enlarged to receive a quantity of mercury by which the float rod H is supported.
The internal form of the float receptacle is shown in Figure 5. The float rod H'
is bored longitudinally and traversed by a conducting wire b' of copper (shown in
Figure 5) which dips in the mercury at its lower end and touches the carbon disc I'
secured to the upper end of the float rod H'or the copper wire is placed in electrical
communication with the carbon disc I' by means of a screw passing through the
centre of the carbon disc into the end of the wooden float rod H' touching the
copper conductor. The float receptacle D' and diaphragm A' are joined up in the
electrical circuit with the battery J' and primary wire c' of the induction coil K¹.
The secondary wire of the coil K¹ is connected with the receiver L¹, ground M¹,
and line N' in the usual way as shown in Figure 4. The primary or battery
current passes through the wire d and float receptacle D' and the mercury con-
tained therein, through the wire 6, in the float rod H¹, carbon disc I¹, carbon
bar G', yokes E¹ F², wire e', and primary wire c' of the induction coil K' to the
battery J'.
When sounds are made in the vicinity of the diaphragm A' it is set in vibration
carrying with it the carbon bar G³, and the bar vibrating more quickly than the
floating disc I, interrupts the current at the point of contact between the two
carbon surfaces and produces audible effects in the receiver connected with the
secondary circuit of the induction coil K¹. I have found by repeated experiments
that this instrument transmits articulate speech with great clearness and loudness,
and have determined by actual and continued trial that it will not get out of
adjustment under the usual conditions of use.
To facilitate packing the instrument for shipping or storage a rubber packing
ring f1 is placed upon the float rod H₁ below the carbon disc I'. The packing
ring is forced down upon the upper end of the float receptacle D' by inserting
a piece of cork between the electrodes G¹ I'.
In the transmitter thus described, the diaphragm must of necessity be placed
in a horizontal position when the instrument is in use. To provide an instrument
with a vertical diaphragm, I interpose between the diaphragm and the carbon
bar electrode, a right angled lever as shown in Figure 7. In this Figure the
several parts shown in Figures 4 and 5 are designated by the same letters of
reference. The diaphragm A¹ is vertical and instead of attaching the yoke Et
directly to the diaphragm, it is secured to the horizontal arm of the right angled
lever O'. The vertical arm of this lever carries an adjusting screw j³ which bears
against the diaphragm A'. The lever O' is fulcrumed on a spring k² sup-
ported by the mouth piece B'. The vibrations of the vertical diaphragm are
transferred to the right angled lever 01 which in turn transfers them to the carbon
electrodes G 11. It is obvious that electrodes of other material than carbon may
be employed. I have made use of the various metals for this purpose, obtaining
in some instances very satisfactory results. For this reason I do not contine
myself to any particular material for the electrodes. The float receptacle D' is
clamped between the fixed arm and the lower arm by the screw so that
it may be adjusted or moved up or down after loosening the screw 1.
It is well known to persons familiar with the operations of the telephone, that
it often happens that the currents induced in a telephone wire by adjacent
telephone or telegraph lines, are far more effective in producing sounds in the
receiving telephone than the legitimate source of sound, and hitherto all attempts
to separate the induced currents of the line from the induction currents of the
telephone transmitter have resulted in failure from the fact that both currents are
of the same nature and whatever tends to weaken or destroy one, will also tend to
weaken or destroy the other. This Invention obviates this difficulty by inter-
rupting the secondary current at every vibration of the diaphragm of the
transmitting instrument so that all currents foreign to the telephone current may

page_text: be utilised in increasing the volume of intelligible sounds in the receiving
instrument by interrupting them so as to compel them to act in unison with the
currents set up in the secondary circuit by the telephone transmitter.
In carrying out this Invention I prefer to employ the above described telephone
transmitter in which one electrode of each set is kept in contact with the opposing
electrode by the buoyant force of a liquid, but I do not confine the Invention to
transmitters of this class.
Referring to Figure 8, two float receptacles D* D* partly filled with mercury
and insulated from each other, are provided with wooden float rods H' H³
supported by the buoyant force of the mercury contained in the receptacles D* D³.
Upon the upper end of these float rods there are carbon discs I' I, one disc on
each float rod communicating with the mercury below by means of a copper wire
as shown in Figure 5 extending through the centre of the rod and dipping into
the mercury. A lever H³ of in-ulating material pivoted centrally upon a
standard projecting from the bottom of the mouth piece B³, carries two
yokes E' E' one on each end of the lever. Each yoke is provided with two pivotal
screws a¹ which enter indentations in opposite sides of the smaller yokes F2 F3
permitting the latter to swing freely in a vertical plane. Short carbon bars G'G'
are fitted to the yokes F2 F3 and are pressed by the carbon discs I' I². The
lever H³ is connected by one of its ends with the diaphragin A' by the flexible
connect on g³ which is in electrical connection with the yoke E' so that when the
diaphragmn is vibrated, the lever H³ is oscillated on its pivot. The mouth piece B³
containing the diaphragm A³, is of the usual description and is supported in any
convenient way in a fixed position in relation to the float receptacles D³ D³. The
primary current from the battery J1 passes over the wire ³, yoke E', screws a³,
yoke F, carbon bar G¹, carbon disc I, wire b' (as in Figure 5) mercury in the
receptacle D2, and wire of the battery. The primary current is interrupted at
the point of contact between the carbon bar G and carbon disc I' whenever the
lever H is oscillated. The line wire M² connects with the yoke E³, and one
terminal of the secondary wire of the induction coil K' communicates with the
mercury in the float receptacle D³ while the other terminal is grounded. A
receiver L² is placed in the secondary circuit between the coil K¹and receptacle D³.
The secondary current of the induction coil passes to the line M³ through the
mercury in the receptacle D³, the float rod H2, carbon disc 12, carbon bar G³,
yoke E³, screws a³, and yoke Fs, and the secondary current is interrupted at the
line of contact between the carbon bar G and the carbon disc I².
Whenever a sound is made in the vicinity of the diaphragm A2, the impact of
an individual sound wave deflects the diaphragm downward and brings the carbon
bar G¹ into close contact with the carbon disc I, ensuring the completion of the
primary circuit, while the same movement raises the carbon bar G³ from the carbon
disc 1 and the secondary or line circuit is for the instant broken. When the
diaphragm A retracts, the carbon bar G2 is brought into contact with the carbon
disc I, completing the secondary circuit at the moment the carbon bar G' leaves
the surface of the carbon disc I¹ interrupting the primary circuit. It will therefore
be noticed that the stronger impulse of the secondary current which occurs when
the primary circuit is broken, has a complete circuit to traverse, the contact
betweeen the carbon bar G2 and carbon disc I² occurring at this instant. The
interruption of the main line circuit practically destroys the effects of induction from
other lines and adds volume to the intelligible sounds heard in the receiving
telephone.
In the modified form of transmitter shown in Figure 9, the interrupter for the
primary circuit is substantially the same as that already described and shown in
Figure 8, and the different parts will therefore be designated by the same letters of
reference; the only essential point of difference is that the yoke El is attached
directly to the diaphragm instead of being attached to a lever as shown in Figure 8.
In this case the carbon disc Is forming one of the electrodes of the secondary
circuit is attached to the top of the diaphragın by an insulating medium n¹ and

page_text: is connected electrically with the secondary wire of the induction coil K'.
Yokes op are supported by the arm N¹ and carry the carbon bar r in the manner
already described in connection with Figure 8. The arm N2 is pivoted between
ears g projecting from the top of the mouthpiece B2 and the line wire M² forms a
connection with the lever N° through the ears q. The primary current passes from
the battery J through the primary wire of the induction coil K¹, wire s, and inter-
mediate devices to the carbon bar G, thence through the carbon disc 1³, the wire
in the float rod, the mercury contained by the receptacle D*, screw 23, to the battery.
The secondary wire of the induction coil K¹³ is grounded through the telephone
receiver L' and the secondary current goes to the line through the carbon disc I³,
carbon bar r, yokes p o, and arin N to the line M². The primary circuit is inter-
rupted with every upward movement of the diaphragm at the line of contact
between the carbon disc I and the carbon bar G, and the secondary circuit is
interrupted at every downward movement of the diaphragm at the line of contact
between the carbon bar r and the carbon disc I³.
The results obtained by this arrangement are substantially the same as those
obtained by the instrument shown in Figure 8.
Figures 10 and 11 represent two forms of the improved telephone repeater. In
carrying out this part of the Invention I employ a straight bar magnet A sur-
rounded by a helix B and supported over the diaphragin C' by an arm D'attached
to the casing containing the diaphragın. For the transmitting portion of the
repeater I use a telephone transmitter similar to that shown in Figure 1, in
which the floating electrode E is pressed upward against a platinum or carbon
contact surface a on the diaphragm C by the buoyant force of the mercury con-
tained in the chamber 6. The line wire is connected with one of the terminals
of the helix B the other terminal being grounded in the usual way. The local
circuit which is operated by the action of the magnet A+ is through the primary
wire of the induction coil g, contact surface a*, floating electrode E, mercury in
the chamber 6, wire e', to the battery ft. The secondary wire of the induction
coil gis arranged and connected in the usual way, that is, one of its terininals
is connected with the line ', and the other is grounded. The helix B' of the
repeater is connected by one of its terminals with the line. Electrical impulses.
sent over the line in the usual way affect the power of the magnet A so that it
alternately attracts and releases the diaphragin C and causes breaks in the local
circuit at the point of contact between the electrode a* and the floating electrode E⭑.
In this way the local circuit is operated in the same manner as it would be
operated if the diaphragm were vibrated by speaking in its vicinity. By this
means impulses are set up in the induction coil g' which are communicated to
the second line . In this manner speech may be cominunicated from one line
to another without material loss, permitting of the extension of telephone lines
beyond the usual working distance.
In the modified forin of telephone repeater shown in Figure 11, the magnet b³ is
made hollow and formed so as to answer the double purpose of magnet and mercury
and float receptacle. The neck A³ of the float receptacle is made of suitable size.
externally to receive the helix B, and internally it is of suitable size to form a
guide for the floating electrode E. An iron diaphragm C³ carries a contact.
point as of carbon or platinum. The float receptacle b is supported by a bracket co
and the mouth piece is supported by a bracket d³. Electrical impulses sent over
the line wire 5 traverse the helix B and affect the strength of the magnet 65 80
that the diaphragm C is vibrated, breaking the contact between the contact
point a³ and the floating electrode E³ interrupting the primary circuit of the
induction coil g whose secondary wire is connected with the second line h³ and
with the ground.
In this manner speech is repeated from one telephone line to another. The
instruments shown in Figures 10 and 11 answer equally as well for telephone
transmitters as for repeaters.
Having described the nature of the said Invention and the manner of performing

page_text: the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is.
1st. In a transmitting telephone, a floating electrode in combination with a
vibratory contact surface as herein specified.
2nd. In a transmitting telephone, an adjustable mercury receiver, a floating
electrode, and a vibratory contact surface in combination as specified.
3rd. In a transmitting telephone, a spring lever O in combination with the
diaphragm C and carbon dise E as herein specified.
4th. The combination of the diaphragm Ċ, lever O, carbon discs E and c and float
rod as specified.
5th. The method of transmitting articulate speech by interrupting an electric
current by means of a vibratory electrode and a float supported electrode, as berein
specified.
6th. In a telephone transmitter employing a float to produce a contact between
two electrodes, the combination of a pivoted vibratory electrode with a plain
surfaced-floating electrode, substantially as specified.
7th. In a telephone transmitter, the combination of the diaphragm A, the
pivoted cylindrical electrode Q' and the floating disc I', substantially as shown and
described.
8th. In a telephone transmitter employing a floating electrode, the combination
of the rubber packing ring f' with the float rod H¹ and float receptacle D'
substantially as specified.
9th. The method of and apparatus for transmitting articulate speech by
interrupted primary and secondary electric currents as herein specified.
10th. In a transmitting telephone, the combination with a vibratory diaphragm
of two pairs of electrodes adapted to be vibrated by the diaphragm in opposite
directions so that the primary and secondary circuits of which they form a part
shall be interrupted in alternation, substantially as herein specified.
11th. In a transmitting telephone, the combination of the lever H³, electrodes G²
1 G2 I* and diaphragm A substantially as specified.
12th. In a transmitting telephone the combination of the primary and secondary
circuits with a double interrupter actuated by a single diaphragin substantially as
herein specified.
13th. The method of destroying the effects of induction from parallel lines
in a telephone line by interrupting the secondary or main line circuit as herein
specified.
14th. In a telephone repeater, the combination of a receiving electro magnet, an
armature diaphragm, and two local circuit contact surfaces, substantially as herein
shown and described.
15th. In a telephone repenter, the combination of the magnet A4, helix B*,
diaphragm C, contact point at and floating electrode E as herein specified.
16th. In a telephone repeater, the combination of the hollow magnet b³, floating
electrode Es, vibratory contact a³ and the line and local circuits, substantially as
specified.
17th. The method of repeating articulate speech from one telephone line to
another by interrupting an electric current in a transmitting device connected
with one line by means of electrical impulses sent over the other line, as herein
specified.
In witness whereof I the said Alexander Melville Clark have hereunto set