IMPROVEMENTS IN MICROPHONIC AND TELEPHONIC APPARATUS
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN MICROPHONIC AND TELEPHONIC APPARATUS." A com-
munication from abroad by Emile Berliner, of Boston, Massachusetts, United
States of America, Electrician.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 8th January 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN MICROPHONIC AND
TELEPHONIC APPARATUS." [A communication from abroad by Emile Berliner, of
Boston, Massachusetts, United States of America, Electrician.]
This Invention relates to improvements in microphones or contact-telephones,
and in other telephones, which improvements comprise the following features,
namely:
:-
First. In a microphone or contact-telephone having no rubbing or frictional
electric contact, maintaining the electrodes in contact with one another with a
variable pressure by the pressure exerted by a body moving or sliding freely by
the action of gravity at an angle inclined to said contact.
Second. In maintaining the electrodes of a microphone or contact-telephone in
contact with one another with a variable pressure by the pressure exerted by &
pendulous weight, which is suspended in such a manner that it is kept from
reaching its point of rest by the interposition of the electrodes, one of which may
be attached to the weight.
Third. In holding the movable electrode in position by means of a magnet acting
on a plate of iron, steel, or other magnetic metal attached to said electrode.
Fourth. In the combination with a diaphragm forming one electrode of a
microphone or contact-telephone or having one electrode attached thereto, of a pin
of metal or carbon forming the other electrode, and maintained in contact with
the diaphragm or the electrode attached thereto by the weight of the pin and of a
device for firmly fixing the pin in position.
Fifth. A damper for the diaphragms of microphones or contact-telephones and

page_text: other telephones, which damper consists of a ring of soft india rubber or of some
other elastic material which is held down upon the diaphragm by a screw passing
through said ring.
Sixth. Carbon electrodes for microphones or contact-telephones, which electrodes
after baving been formed into the desired shape are hardened by being heated in
the presence of hydro-carbons, and are afterwards polished.
In carrying the said Invention into practice I provide in a microphone or
contact-telephone a block of wood, vulcanite, or other similar material having a
recess upon its face, and opposite to this recess is fastened a metal diaphragm by
screws; a block of metal is furnished on the other side of the diaphragm, which
block is also recessed opposite to the diaphragm, and into this block the screws
pass so as to firmly clamp the diaphragm between the said blocks. In the block
opposite to the centre of the diaphragm is an opening, into which is fixed a mouth-
piece on the back of the diaphragm is suitably secured a block of carbon, and
opposite to this carbon block is an inclined opening or perforation in the first named
block, elliptical in section, or angular, or circular in section, in which opening or
perforation rests loosely a pin or cylinder, which sliding freely in the inclined
opening is maintained by its weight in contact at its extremitity with the face of
the carbon block. This cylinder must be made of metal or carbon, or have the
extremity in contact with the last named block of metal or carbon, and a desirable
way of making it is to use metal for the body of the cylinder or pin, and carbon for
the tip in contact with the last named block. This tip may be attached to the
metal body of the pin or cylinder by spinning a part of the latter around the tip,
and it is desirable in order to obtain as small a surface of contact as possible
between the last named block and the tip that the latter should be convex upon
its face. The face of this block may be parallel with the diaphragm or it may be
inclined at an angle to the diaphragm or convex. The last named block, instead
of being made of carbon may be made of metal, or the block may be dispensed
with, and the end of the pin may rest directly upon the surface of the diaphragm,
provided the latter is made of some conducting substance, such as carbon or
metal, for in some cases it may be desirable to make the diaphragmn of some non-
conducting substance. One pole of a galvanic battery is connected to the carbon
or metal part of the pin, and the other pole of the said battery is connected to the
diaphragm if the latter is a conductor, or if not to the block on the diaphragm.
The extremity of the pin therefore forms one electrode of the battery, and the
diaphragm or block the other electrode.
The primary coil of an induction coil is connected in this circuit for the reason
that an induction coil is generally used in connection with a microphone when
the latter is used as a transmitter of sounds, the microphone being placed in
the circuit of the primary coil and the telephone which is used as the sound-
receiver in the circuit of the secondary coil. The connection of the pin with
this battery must be of such a character that it will not interfere with or
prevent the free movement of the pin in its inclined support. This result
may be accomplished by the use of a pliable wire or other conductor for
connecting the pin to a point in the first named block, from which a wire
passes to the battery, or it may be accomplished by connecting this pin to the
battery by means of a cup of mercury. The first named block need not be used
for clamping the diaphragm to the second block, and for supporting the pin, and
the diaphragm may be clamped in any suitable manner, and the pin be supported
in any manner which will permit it to slide freely towards the diaphragm by its
own weight. I provide a metal spring, which at one end is fixed to the first
named block, and at the other end bears upon the diaphragm. The end in contact
with the diaphragm is covered with soft rubber. This spring acts as a damper,
and will not be required when a diaphragm is used, which has but little vibration,
as for instance, one of carbon or hard wood.
I also provide a microphone or contact-telephone embodying the following
improvements, that is to say :-I provide a metal support for a mouth-piece which

page_text: support is provided with an opening for the insertion of the mouth-piece, and to
this support the diaphragm is secured by screws, or in any other suitable manner,
a recess being formed between the diaphragm and the back of the support. To the
centre of the diaphragm opposite the mouth-piece is fixed a carbon-block forming one
electrode of an electric circuit, and having a smooth surface parallel to the surface of
the diaphragm. The other electrode consists of a piece of carbon, convex and
polished upon its face, and fixed in any suitable manner in a metallic cylinder.
This cylinder has attached to it at right angles by a screw or in any other suitable
manner a metal plate, a little longer and wider than the cylinder. A strip of
metal is attached at one end to the diaphragm near its edge in any suitable manner,
as for instance, by a screw, and this strip is inclined outwards from the diaphragm,
and is of such length that the edge of the plate rests upon its free end. To this
strip near its point of attachment to the diaphragm is attached one end of a ribon
or band of some flexible conducting material, such as metallic foil, or a metallic
web, or fabric, or cloth, paper, or leather, or some similar flexible substance,
metallized or otherwise rendered conducting, and the other end of this band or
ribbon is attached to the plate.
The cylinder and band or ribbon thus form a pendulum which has its point of
suspension above the carbon-block, and is prevented from reaching its point of rest
by the contact of the carbon-piece with the carbon block, and consequently bears
upon the face of the said block with a force proportional to the weight of the cylinder,
and the distance of the centre of gravity of the pendulum from its point of rest.
This microphone can therefore be adjusted to any desired degree of sensibility,
either by varying the distance of the surface of the carbon block from the surface
of the diaphragm, so as to increase the inclination of the pendulum, or by adjusting
a movable weight on the cylinder in such a manner as to vary the distance of the
centre of gravity of the pendulum from the surface of the carbon block. This
weight may be the screw attached to the cylinder.
It is important in a microphone or contact-telephone in order to ensure the clear
transmission of sounds, especially of articulate sounds that the suspended electrode
should be prevented from oscillating from side to side on the fixed electrode or
from having a rotary movement on the same, which result will be accomplished by
holding this suspended electrode in position from at least two points on opposite
sides of its centre of gravity. The object of the band or ribbon for suspending
the cylinder in the instrument which has been described is for the purpose of
accomplishing this result by preventing the effects of torsion, but the same result
can be accomplished by other means, and this Invention is not limited to the use
of a ribbon or band for suspending the electrode. The support afforded to the
plate by the end of the strip contributes to preventing the suspended electrode
from rotating or from oscillating from side to side on the block. The electrodes
instead of being made of carbon can be made of any conducting substance.
In one form of microphone or contact-telephone I make one of the electrodes of
platinum and it is attached to a light metallic spring which forms part of the
circuit. In this case the pendulous weight rests upon this electrode, and the band
or ribbon supporting the same need not be a conductor.
In another form of microphone or contact-telephone the transmission of sounds
is obtained by the vibration of pressure upon a button of finely divided carbon
enclosed between the diaphragm and the pendulous weight. In this case also the
band or ribbon need not be a conductor.
I also provide a microphone or contact-telephone with the following improvements,
that is to say:-
In an instrument so provided the cylinder, to the extremity of which the electrode
is fixed, has attached to it a plate of iron or steel which forms the armature of a
vertical magnet attached to the diaphragm or to the support for the same. By the
use of a second armature the attractive force of this magnet on the iron or steel
plate can be varied as may be desired,

page_text: I also provide a microphone or contact-telephone with the following improvements,
that is to say-The instrument having these improvements is similar in its
construction to that first herein described, with the exception that the diaphragm
is made wholly of carbon, though it may be made as in the instruments herein
before described, and the opening in the first named block for the insertion of the
carbon or metallic pin is at right angles to the diaphragm. The instrument is
adjusted for use by dropping the pin into the perforation, and when it has made
contact with the diaphragm by its weight fixing it in position by a suitable
clamping device, as for example, the clamp and nut herein before described.
The improved damper herein before mentioned consists of a ring of soft india-
rubber or some other similar elastic material which is placed between the diaphragm
and the head of the screw which secures the diaphragm to its support and is held
against the diaphragm by said screw. The transmission of sounds by microphones
⚫ or contact-telephones is improved in clearness by having the electrodes polished
upon the surfaces in contact with one another, and in order that this may be the
case when carbon electrodes are used they are preferably made of a hardened
carbon which is capable of being polished. This carbon is prepared from some
semi-hard and homogeneous carbon, such as that from which the pencils used in
the production of the electric light are made, by exposing it for about twelve
hours in pieces of the size and shape which it is intended to use in the construction
of the electrodes of the microphone to a high temperature in a retort in which
hydro-carbons are being generated, as for instance, a retort in which illuminating
gas is being made.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 7th
July 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN MICROPHONIC AND
TELEPHONIC APPARATUS." A communication from abroad by Emile Berliner, of
Boston, Massachusetts, United States of America, Electrician.
This Invention relates to improvements in microphones or contact telephones, and
in other telephones.
According to these improvements the electrodes in a microphone or contact
telephone having no rubbing or frictional electric contact are maintained in contact
with one another with a variable pressure by the pressure exerted by a body
moving or sliding freely through the action of gravity at an angle inclined to
such contact. I also maintain the electrodes of a microphone or contact-telephone
in contact with one another with a variable pressure by the pressure exerted by a
pendulous weight, which is suspended in such a manner that it is kept from
reaching its point of rest by the interposition of the electrodes, one of which may
be attached to the weight. In combination with the said pendulous weight I
employ an adjusting device, whereby its angle of inclination to the other electrode
and its pressure upon the same can be varied at will. I also combine with the
vibrating surface of the microphone or contact-telephone an elastic arm to which
one of the electrodes is attached, and an adjusting screw the point of which is in
contact with the said surface. According to these improvements I also hold the
movable electrode in position by means of a magnet acting on a plate of iron,
steel, or other magnetic metal attached to the said electrode. I also combine with
a diaphragm forming one electrode of a microphone or contact-telephone having
one electrode attached thereto, a pin of metal or carbon forming the other electrode
and maintained in contact with the diaphragm or the electrode attached thereto by
the weight of the pin, and also a device for firmly fixing the said pin in position.
I also provide a damper for the diaphragms of microphones or contact-telephonės,
and other telephones, which damper consists of a ring of soft india-rubber or of some
other elastic material which is held down upon the diaphragm by a screw passing
through the said ring. I also employ carbon electrodes for microphones or contact-
telephones, which electrodes after having been formed into the desired shape are
hardened by being heated in the presence of hydro-carbons, and are afterwards
polished.
In the accompanying Drawing,-
Figure 1 is a vertical central section of a microphone or contact-telephone
embodying some of the said improvements, and
Figure 2 is a back view of the same.
Figure 3 is a vertical section of another form of microphone or contact-telephone
constructed according to this Invention.
Figure 4 is a perspective view of the clamping device used with this form of
microphone or contact-telephone.
Figure 5 is a section of my improved damper hereinafter described.
Figure 6 is a perspective view of the back of a microphone or contact-telephone
shewing the same provided with a pendulous weight having an adjusting device
and an elastic arm and adjusting screw hereinafter referred to.
Figure 7 is a section of the same on the line x, x, Figure 6.
Figure 8 is a perspective view of the back of a microphone or contact-telephone
embodying other improvements hereinafter set forth.
Figure 9 is a section of the same on the line x1, x¹, Figure 8.
Figure 10 is a perspective view of a microphone or contact-telephone in which
the movable electrode is held in position by a magnet.

page_text: Figures 11, 12, and 13, are views in section of other forms of microphone or
contact-telephones hereinafter described.
Figure 14 shews the method of connecting the sliding electrode to the battery by
means of mercury.
Figures 15 and 16 shew modifications in the form of the fixed electrode.
Figure 17 shews modifications in the form of the support for the sliding
electrode.
Like letters indicate the same parts throughout the Drawing.
In the microphone or contact-telephone, shewn in Figures 1 and 2, A represents a
block of wood, vulcanite, or other similar material having a recess upon its face,
and opposite to this recess is fastened the metal diaphragm B by the screws a;
Cis
a block of metal on the side of the diaphragm opposite to the block A; this block C
is also recessed opposite to the diaphragm, and into this block the screws a pass to
firmly clamp the diaphragm between the blocks A and C. In the block C opposite
to the centre of the diaphragm is an opening into which is fixed the mouth-piece D.
On the back of the diaphragm is suitably secured a block E of carbon, and opposite
to this carbon block is an inclined opening or perforation in the block A elliptical
in section, as shewn in Figure 2, or angular or circular in section, as shewn in
Figure 17; in this opening or perforation rests loosely a pin or cylinder F which,
sliding freely in the said inclined opening, is maintained by its weight in contact at its
extremity with the face of the carbon block E. This cylinder must be made of metal or
carbon, or the extremity in contact with the block E must be of metal or carbon.
An advantageous method of making the cylinder is to use metal for the body of
the said cylinder, or pin and carbon for the tip b in contact with the block E, as
shewn in the Drawing. This tip may be attached to the metal body of the pin or
cylinder by spinning a part of the latter around the tip, and it is desirable in order
to obtain as small a surface of contact as possible between the block E and the tip b
that the latter should be convex upon its face. The face of the block E may be
parallel with the diaphragm, or it may be inclined at an angle to the diaphragm,
as shewn in Figure 15, or convex, as shewn in Figure 16.
The block E instead of being made of carbon may be made of metal, or the block
may be dispensed with, and the end of the pin F may rest directly upon the surface
of the diaphragm, provided the latter is made of some conducting substance such as
carbon or metal; in some cases, however, it may be desirable to make the diaphragm
of some non-conducting substance.
One pole of a galvanic battery is connected to the metal or carbon part of the
pin F, and the other pole of the said battery is connected to the diaphragm if the
latter is a conductor, or if not to the block E on the diaphragm.
The extremity of the pin therefore forms one electrode of the battery, and the
diaphragm or block the other electrode.
In Figures 1 and 2 the primary coil of an induction-coil G is shewn connected
in this circuit for the reason that an induction-coil is generally used in connection
with a microphone when the latter is used as a transmitter of sounds, the micro-
phone being placed in the circuit of the primary coil, and the telephone, which is
used as the sound-receiver, in the circuit of the secondary coil.
The connection of the pin F with this battery must be of such a character that it
will not interfere with or prevent the free movement of the pin in its inclined
support. This result may be accomplished by the use of a pliable or flexible wire
or other conductor c, as shewn in Figures 1 and 2, for connecting the pin F to a
point in the block A from which a wire passes to the battery, or it may be accom-
plished by connecting this pin to the battery by means of a cup of mercury d, as
shewn in Figure 14. The block A need not be used for clamping the diaphragm
to the block C, and for supporting the pin F, and the diaphragm may be clamped
in any suitable manner and the pin be supported in any manner which will permit
it to slide freely towards the diaphragm by its own weight. H is a metal spring
which at one end is fixed to the block A and at the other end bears upon the
diaphragm; the end of the said spring in contact with the diaphragm is covered

page_text: with soft india rubber. This spring acts as a damper and will not be required when
a diaphragm is used which has but little vibration, as, for instance, one of carbon
or hard wood.
Referring to the microphone or contact-telephone, shown in Figures 8 and 9, C is
the metal support for the mouth-piece D; this support is provided with an opening
for the insertion of the mouth-piece, and has the diaphragm B secured to it by
screws or in any other suitable manner, a recess being formed between the diaphragm
and the back of the said support C. To the centre of the diaphragm opposite the
mouth-piece is fixed a carbon block E forming one electrode of an electric circuit
and having a smooth surface parallel to the surface of the diaphragm. The other
electrode consists of a piece of carbon b convex and polished upon its face and fixed
in any suitable manner in a metallic cylinder F. This cylinder has attached to it
at right angles by a screw K, or in any other suitable manner, a metal plate I a
little longer and wider than the cylinder F. Lis a strip of metal which is attached
at one end to the diaphragm near its edge in any suitable manner, as, for instance,
by a screw M, as shewn in the Drawing, and this strip L is inclined outwards from
the diaphragm and is of such length that the edge of the plate I rests upon its free
end. To this strip L near its point of attachment to the diaphragm is attached one
end of a ribbon or band O of some flexible conducting material such as metallic foil,
or a metallic web or fabric of cloth, paper, or leather, or some similar flexible
substance metallized or otherwise rendered conducting, and the other end of this
band or ribbon O is attached to the plate I.
Instead of making this band of some flexible material it can be made of rigid
material in two parts, connected by a binge, as shewn in Figure 13. In this
manner the desired flexibility will be secured.
The cylinder F and band or ribbon O thus form a pendulum, which has its point of
suspension above the carbon block E, and is prevented from reaching its point of rest
by the contact of the carbon piece b with the carbon block E, and consequently bears
upon the face of said block with a force proportional to the weight of the cylinder
and the distance of the centre of gravity of the pendulum from its point of rest.
This microphone can therefore be adjusted to any desired degree of sensibility,
either by varying the distance of the surface of the carbon block Ĕ from the surface
of the diaphragm so as to increase the inclination of the pendulum or by adjusting
a movable weight on the cylinder in such a manner as to vary the distance of the
centre of gravity of the pendulum from the surface of the carbon block E. This
weight may be the screw K.
A convenient manner of effecting this adjustment is shown in Figures 6 and 7,
in which A is the block which supports the vibrating diaphragm B; E is the fixed
electrode; and S is an elastic plate of metal, which is fixed at one extremity by a
screw M or in any other suitable manner to the top of the block A, and is free at
its other end. This end is made annular so as to surround the carbon electrode E,
A screw M¹ passes
and to this plate the support L of the strip O is attached.
through the lower end of the plate S, and bears upon a piece of soft rubber a, on
the diaphragm B. By means of this screw M¹ the distance of the lower extremity
of the plate S from the vibrating diaphragm can be varied at will, thus changing
the angle of inclination of the movable electrode to the surface of the fixed
electrode.
It is important in a microphone or contact-telephone in order to ensure the clear
transmission of sounds, especially of articulate sounds that the suspended electrode
should be prevented from oscillating from side to side on the fixed electrode or
from having a rotary movement on the same, which result will be accomplished by
bolding this suspended electrode in position from at least two points on opposite
sides of its centre of gravity. The object of the band or ribbon for suspending the
cylinder F in the instrument which has been described is for the purpose of
accomplishing this result by preventing the effect of torsion, but the same result
may be accomplished by other means. I do not therefore limit myself to the use
of a ribbon or band for suspending the electrode.

page_text: The support afforded to the plate I, by the end of the strip L, assists in pre-
venting the suspended electrode from rotating or from oscillating from side to side
on the block E.
The electrodes b and E, instead of being made of carbon, can be made of any
conducting substance.
Figure 11 represents a form of microphone or contact-telephone, in which one of
the electrodes b is made of platinum, and is attached to a light metallic spring a¹,
which forms part of the circuit. In this case the pendulous weight rests upon
the electrode b, and the band or ribbon supporting the same need not be a
conductor.
Figure 10 shews a microphone or contact-telephone in which the cylinder F, to
the extremity of which the electrode b is fixed, has attached to it a plate of iron or
steel I, which forms the armature of a vertical magnet N, attached to the diaphragm
or to the support for the same. By the use of a second armature the attractive
force of this magnet on the plate I can be varied as may be desired.
Figure 12 shews another form of microphone or contact-telephone in which the
transmission of sounds is obtained by the variation of pressure upon a button of
finely divided carbon enclosed between the diaphragm and the pendulous weight.
In this case also the band or ribbon O need not be a conductor.
The microphone or contact-telephone shewn in Figure 3 is similar in its con-
struction to that shewn in Figures 1 and 2 with the exception that the diaphragm
is made wholly of carbon, though it may be made as in the instrument before
described, and the opening in the block A, for the insertion of the carbon or
metallic pin F, is at right angles to the diaphragm. The instrument is adjusted
for use by dropping the pin into the perforation, and when it has made contact
with the diaphragm by its weight, fixing in position by a suitable clamping
device, as, for example, the clamp and nut shewn in Figure 4.
The improved damper shewn in Figure 5 consists of a ring d¹ of soft india-
rubber or other similar elastic material, which is placed between the diaphragm
and the head of the screw that secures the diaphragm to its support, and is held
against the diaphragm by the said screw. The transmission of sounds by micro-
phones or contact-telephones is improved in clearness by having the electrodes
polished upon the surfaces in contact with one another, and in order that this may
be the case when carbon electrodes are used they are preferably made of a hardened
carbon, which is capable of being polished.
This carbon is prepared from some semi-hard and homogeneous carbon, such as
that from which the pencils used in the production of the electric light are made
by exposing it for about twelve hours in pieces of the size and shape which it is
intended to use in the construction of the electrodes of the microphone to a high
temperature in a retort in which hydro-carbons are being generated, as, for instance,
a retort in which illuminating gas is being made.
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. A microphone or contact-telephone having no rubbing or frictional electric
contact, and having the electrodes maintained in contact with one another, with a
variable pressure by the pressure exerted by a body moving or sliding freely by the
action of gravity at an angle inclined to such contact, substantially as above set
forth and for the purpose specified.
Second. In a microphone or contact-telephone having no frictional or rubbing
electric contact, the combination with a vibrating surface forming one electrode of
a pin forming the opposite electrode, and sliding freely on a suitable support
inclined at an angle to the vibrating surface, and connected to the battery in such
a manner that its free movement on the support will not be interfered with, all
substantially as above set forth and for the purpose specified.
Third. In combination with a vibrating surface forming one electrode the block A
provided with an opening or perforation inclined downwards to the vibrating
.

page_text: surface, a conducting pin or cylinder having a carbon extremity and sliding freely
in the said inclined opening so as to make contact at its extremity with the
vibrating surface and connection between said pin and the battery, which will not
interfere with the free movement of the pin or cylinder, all substantially as above
set forth and for the purpose specified.
Fourth. The combination of the diaphragm, the carbon block E, the damper H,
the block A, the pin sliding freely in an inclined opening in the said block and
the flexible conductor c, substantially as above set forth and for the purpose
specified.
Fifth. A microphone or contact-telephone having only one contact affected by
sound-waves and consisting of two electrodes in contact with one another, which
contact is varied during the transmission of sounds by the variation in the pressure
upon such contact of a pendulous weight which is kept out of its point of rest by
the interposition of said electrodes, and is supported in such a manner that there is
no lateral movement or pressure between the electrodes, all substantially as above
set forth and for the purpose specified.
Sixth. In a microphone or contact-telephone the combination of a vibrating
surface forming one electrode, a pendulous weight forming the opposite electrode
with or without a device for changing the inclination of the said weight and a
band or ribbon of flexible material suspending the said weight, which band or
ribbon may or may not be a conductor, substantially as above set forth and for the
purpose specified.
Seventh. In a contact-telephone or microphone the combination of the flexible
band O or hinge and the supporting strip L, substantially as above set forth and
for the purpose specified.
Eighth. In a microphone or contact-telephone the combination of the diaphragm,
the carbon block E, the carbon tip b, the adjustable weight F, the plate I, the
flexible band O, or hinge and the supporting strip L with or without the frame S
and adjusting screw M¹, substantially as above set forth and for the purpose
specified.
Ninth. A damper (for the diaphragms of telephones or microphones) consisting of
a ring of soft india-rubber or other elastic material held down upon the diaphragm
by a screw passing through said ring, substantially as above set forth and for the
purpose specified.
Tenth. In combination with a diaphragm, of carbon or other meterial forming
one electrode, the self-adjusting opposite electrode capable of sliding into contact
with the diaphragm and of being firmly fixed in position after having adjusted
itself in said contact, substantially as above set forth and for the purpose specified.
Eleventh. In a microphone or contact-telephone having no rubbing or frictional
electrical contact, the combination with a diaphragm forming one electrode of the
opposite non-elastic electrode, capable of sliding freely towards the diaphragm until
both electrodes come into contact with each other, substantially as above set forth
and for the purpose specified.
Twelfth. The combination of two opposite electrodes, one of which has its weight
so regulated as to exert pressure upon the other, and slides towards the same, and
is capable of being firmly fixed in position, substantially as above set forth and for
the purpose specified.
Thirteenth. The combination of the diaphragm, the blocks A and C (the block A
being provided with a perforation therein at right angles to the diaphragm), the
conducting pin F sliding in the said perforation into contact at its extremity with
the diaphragm, and a device for firmly fixing this pin in position, all substantially
as above set forth and for the purpose.
Fourteenth. In a microphone or contact-telephone an electrode suspended from
and held in position by a permanent magnet, substantially as above set forth and
for the purpose specified.
Fifteenth. In a microphone or contact-telephone a carbon electrode, which is
first formed into the required form and afterwards hardened by being heated in

page_text: presence of hydro-carbons, substantially as above set forth and for the purpose
specified.
Sixteenth. In a microphone or contact-telephone a vibrating surface, forming one
electrode, a damping device bearing against said surface, and a pendulous electrode
in contact with said vibrating surfaces, and suspended from at least two points
which are situated on opposite sides of the centre of gravity of said pendulous
weight, substantially as above set forth and for the purpose specified.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Seventh day of July, in the year of our Lord One
thousand eight hundred and eighty.

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Sonthampton Buildings, London, for an Invention of
A com-
"IMPROVEMENTS IN MICROPHONIO AND TELEPHONIC APPARATUS."
munication from abroad by Emile Berliuer, of Boston, Massachusetts, United
States of America, Electrician.
PROVISIONAL SPECIFICATION left by the sail William Robert Lake at the
Office of the Commissioners of Patents on the 8th January 1880
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
"IMPROVEMENTS IN MICROPHONIC AND
Agents, Southampton Buildings, London.
TELEPHONIC APPARATUS." [A communication from abroad by Emile Berliner, of
Boston, Massachusetts, United States of America, Electrician.]
This Invention relates to improvements in microphones or contact-telephones,
and in other telephones, which improvements comprise the following features,
namely:-
:-
First. In a microphone or contact-telephone having no rubbing or frictional
electric contact, maintaining the electrodes in contact with one another with a
variable pressure by the pressure exerted by a body moving or sliding freely by
the action of gravity at an angle inclined to said contact.
Second. In maintaining the electrodes of a microphone or contact-telephone in
contact with one another with a variable pressure by the pressure exerted by a
pendulous weight, which is suspended in such a manner that it is kept from
reaching its point of rest by the interposition of the electrodes, one of which may
be attached to the weight.
Third. In holding the movable electrode in position by means of a magnet acting
on a plate of iron, steel, or other magnetic metal attached to said electrode.
Fourth. In the combination with a diaphragm forming one electrode of a
microphone or contact-telephone or having one electrode attached thereto, of a pin
of metal or carbon forming the other electrode, and maintained in contact with
the diaphragm or the electrode attached thereto by the weight of the pin and of a
device for firmly fixing the pin in position.
Fifth. A damper for the diaphragms of microphones or contact-telephones and

page_text: other telephones, which damper consists of a ring of soft india rubber or of some
other elastic material which is held down upon the diaphragm by a screw passing
through said ring.
Sixth. Carbon electrodes for microphones or contact-telephones, which electrodes
after having been formed into the desired shape are hardened by being heated in
the presence of hydro-carbons, and are afterwards polished.
In carrying the said Invention into practice I provide in a microphone or
contact-telephone a block of wood, vulcanite, or other similar material having a
recess upon its face, and opposite to this recess is fastened a metal diaphragm by
screws; a block of metal is furnished on the other side of the diaphragm, which
block is also recessed opposite to the diaphragm, and into this block the screws
pass so as to firmly clamp the diaphragm between the said blocks. In the block
opposite to the centre of the diaphragm is an opening, into which is fixed a mouth-
piece on the back of the diaphragm is suitably secured a block of carbon, and
opposite to this carbon block is an inclined opening or perforation in the first named
block, elliptical in section, or angular, or circular in section, in which opening or
perforation rests loosely a pin or cylinder, which sliding freely in the inclined
opening is maintained by its weight in contact at its extremity with the face of
the carbon block. This cylinder must be made of metal or carbon, or have the
extremity in contact with the last named block of metal or carbon, and a desirable
way of making it is to use metal for the body of the cylinder or pin, and carbon for
the tip in contact with the last named block: This tip may be attached to the
metal body of the pin or cylinder by spinning a part of the latter around the tip,
and it is desirable in order to obtain as small a surface of contact as possible
between the last named block and the tip that the latter should be convex upon
its face. The face of this block may be parallel with the diaphragm or it may be
inclined at an angle to the diaphragm or convex. The last named block, instead
of being made of carbon may be made of metal, or the block may be dispensed
with, and the end of the pin may rest directly upon the surface of the diaphragm,
provided the latter is made of some conducting substance, such as carbon or
metal, for in some cases it may be desirable to make the diaphragm of some non-
conducting substance. One pole of a galvanic battery is connected to the carbon
or metal part of the pin, and the other pole of the said battery is connected to the
diaphragm if the latter is a conductor, or if not to the block on the diaphragm.
The extremity of the pin therefore forms one electrode of the battery, and the
diaphragm or block the other electrode.
The primary coil of an induction coil is connected in this circuit for the reason
that an induction coil is generally used in connection with a microphone when
the latter is used as a transmitter of sounds, the microphone being placed in
the circuit of the primary coil and the telephone which is used as the sound-
receiver in the circuit of the secondary coil. The connection of the pin with
this battery must be of such a character that it will not interfere with or
prevent the free movement of the pin in its inclined support. This result
may be accomplished by the use of a pliable wire or other conductor for
connecting the pin to a point in the first named block, from which a wire
passes to the battery, or it may be accomplished by connecting this pin to the
battery by means of a cup of mercury.
for clamping the diaphragm to the second block, and for supporting the pin, and
the diaphragm may be clamped in any suitable manner, and the pin be supported
in any manner which will permit it to slide freely towards the diaphragm by its
own weight. I provide a metal spring, which at one end is fixed to the first
named block, and at the other end bears upon the diaphragm. The end in contact
with the diaphragm is covered with soft rubber. This spring acts as a damper,
and will not be required when a diaphragm is used, which has but little vibration,
as for 'instance, one of carbon or hard wood.
The first named block need not be used
I also provide a microphone or contact-telephone embodying the following
improvements, that is to say :-I provide a metal support for a mouth-piece which,

page_text: support is provided with an opening for the insertion of the mouth-piece, and to
this support the diaphragm is secured by screws, or in any other suitable manner,
a recess being formed between the diaphragm and the back of the support. To the
centre of the diaphragm opposite the mouth-piece is fixed a carbon-block forming one
electrode of an electric circuit, and having a smooth surface parallel to the surface of
the diaphragm. The other electrode consists of a piece of carbon, convex and
polished upon its face, and fixed in any suitable manner in a metallic cylinder.
This cylinder has attached to it at right angles by a screw or in any other suitable
manner a metal plate, a little longer and wider than the cylinder. A strip of
metal is attached at one end to the diaphragm near its edge in any suitable manner,
as for instance, by a screw, and this strip is inclined outwards from the diaphragm,
and is of such length that the edge of the plate rests upon its free end. To this
strip near its point of attachment to the diaphragm is attached one end of a ribon
or band of some flexible conducting material, such as metallic foil, or a metallic
web, or fabric, or cloth, paper, or leather, or some similar flexible substance,
metallized or otherwise rendered conducting, and the other end of this band or
ribbon is attached to the plate.
The cylinder and band or ribbon thus form a pendulum which has its point of
suspension above the carbon-block, and is prevented from reaching its point of rest
by the contact of the carbon-piece with the carbon block, and consequently bears
upon the face of the said block with a force proportional to the weight of the cylinder,
and the distance of the centre of gravity of the pendulum from its point of rest.
This microphone can therefore be adjusted to any desired degree of sensibility,
either by varying the distance of the surface of the carbon block from the surface
of the diaphragm, so as to increase the inclination of the pendulum, or by adjusting
a movable weight on the cylinder in such a manner as to vary the distance of the
This
centre of gravity of the pendulum from the surface of the carbon block.
weight may be the screw attached to the cylinder.
It is important in a microphone or contact-telephone in order to ensure the clear
transmission of sounds, especially of articulate sounds that the suspended electrode
should be prevented from oscillating from side to side on the fixed. electrode or
from having a rotary movement on the same, which result will be accomplished by
holding this suspended electrode in position from at least two points on opposite
sides of its centre of gravity. The object of the band or ribbon for suspending
the cylinder in the instrument which has been described is for the purpose of
accomplishing this result by preventing the effects of torsion, but the same result
can be accomplished by other means, and this Invention is not limited to the use
of a ribbon or band for suspending the electrode. The support afforded to the
plate by the end of the strip contributes to preventing the suspended electrode
from rotating or from oscillating from side to side on the block. The electrodes
instead of being made of carbon can be made of any conducting substanco.
In one form of microphone or contact-telephone I make one of the electrodes of
platinum and it is attached to a light metallic spring which forms part of the
circuit. In this case the pendulous weight rests upon this electrode, and the band
or ribbon supporting the saine need not be a conductor.
In another forin of microphone or contact-telephone the transmission of sounds
is obtained by the vibration of pressure upon a button of finely divided carbon
enclosed between the diaphragm and the pendulous weight. In this case also the
band or ribbon need not be a conductor.
I also provide a microphone or contact-telephone with the following improvements,
that is to say :-
In an instrument so provided the cylinder, to the extremity of which the electrode
is fixed, has attached to it a plate of iron or steel which forms the armature of a
vertical magnet attached to the diaphragm or to the support for the same. By the
use of a second armature the attractive force of this magnet on the iron or steel
plate can be varied as may be desired.

page_text: I also provide a microphone or contact-telephone with the following improvements,
that is to say :-The instrument having these improvements is similar in its
construction to that first herein described, with the exception that the diaphragm
is made wholly of carbon, though it may be made as in the instruments herein
before described, and the opening in the first named block for the insertion of the
carbon or metallic pin is at right angles to the diaphragm. The instrument is
adjusted for use by dropping the pin into the perforation, and when it has made
contact with the diaphragm by its weight fixing it in position by a suitable
clamping device, as for example, the clamp and nut herein before described.
The improved damper hereinbefore mentioned consists of a ring of soft india-
rubber or some other similar elastic material which is placed between the diaphragm
and the head of the screw which secures the diaphragm to its support and is held
against the diaphragm by said screw. The transmission of sounds by microphones
or contact-telephones is improved in clearness by having the electrodes polished
upon the surfaces in contact with one another, and in order that this may be the
case when carbon electrodes are used they are preferably made of a hardened
carbon which is capable of being polished. This carbon is prepared from some
semi-hard and homogeneous carbon, such as that from which the pencils used in
the production of the electric light are made, by exposing it for about twelve
hours in pieces of the size and shape which it is intended to use in the construction
of the electrodes of the microphone to a high temperature in a retort in which
hydro-carbons are being generated, as for instance, a retort in which illuminating
gas is being made.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 7th
July 1880.
$.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent
Agents, Southampton Buildings, London. "IMPROVEMENTS IN MICROPHONIC AND
TELEPHONIC APPARATUS." A communication from abroad by Emile Berliner, of
Boston, Massachusetts, United States of America, Electrician.
This Invention relates to improvements in microphones or contact telephones, and
in other telephones.
According to these improvements the electrodes in a microphone or contact
telephone having no rubbing or frictional electric contact are maintained in contact
with one another with a variable pressure by the pressure exerted by a body
moving or sliding freely through the action of gravity at an angle inclined to
such contact. I also maintain ilio electrodes of a microphone or contact-telephone
in contact with one another with a variable pressure by the pressure exerted by a
pendulous weight, which is suspended in such a manner that it
kept from
reaching its point of rest by the interposition of the electrodes, one of which may
be attached to the weight. In combination with the said pendulous weight I
employ an adjusting device, whereby its angle of inclination to the other electrode
and its pressure upon the same can be varied at will. I also combine with the
vibrating surface of the microphone or contact-telephone an elastic arm to which
one of the electrodes is attached, and an adjusting screw the point of which is in
contact with, the said surface. According to these improvements I also hold the
movable electrode in position by means of a magnet acting on a plate of iron,
steel, or other magnetic metal attached to the said electrode. I also combine with
a diaphragm forming one electrode of a microphone or contact-telephone having
one electrode attached thereto, a pin of metal or carbon forming the other electrode
and maintained in contact with the diaphragm or the electrode attached thereto by
the weight of the pin, and also a device for firmly fixing the said pin in position.
I also provide a damper. for the diaphragms of microphones or contact-telephones,
and other telephones, which damper consists of a ring of soft india-rubber or of some
other elastic material which is held down upon the diaphragm by a screw passing
through the said ring. I also employ carbon electrodes for microphones or contact-
telephones, which electrodes after having been formed into the desired shape are
hardened by being heated in the presence of hydro-carbons, and are afterwards
polished.
In the accompanying Drawing,-
Figure 1 is a vertical central section of a microphone or contact-telephone
embodying some of the said improvements, and
Figure 2 is a back view of the same.
Figure 3 is a vertical section of another form of microphone or contact-telephone
constructed according to this Invention.
Figure 4 is a perspective view of the clamping device used with this form of
microphone or contact-ielephone.
Figure 5 is a section of my improved damper hereinafter described.
Figure 6 is a perspective view of the back of a microphone or contact-telephone
shewing the same provided with a pendulous weight having an adjusting device
and an elastic-arm and adjusting screw hereinafter referred to.
Figure 7 is a section of the same on the line x, x, Figure 6.
Figure 8 is a perspective view of the back of a microphone or. contact-telephone
embodying other improvements hereinafter set forth.
Figure 9 is a section of the same on the line ¹, x¹, Figure 8.
Figure 10 is a perspective view of a microphone or contact-telephone in which
the movable electrode is held in position by a magnet.

page_text: i
Figures 11, 12, and 13, are views in section of other forms of microphone or
contact-telephones hereinafter described.
Figure 14 shews the method of connecting the sliding electrode to the battery by
means of mercury.
Figures 15 and 16 shew modifications in the form of the fixed electrode.
Figure 17 shews modifications in the form of the support for the sliding
electrode.
Like letters indicate the same parts throughout the Drawing.
In the microphone or contact-telephone, shewn in Figures 1 and 2, A represents a
block of wood, vulcanite, or other similar material having a recess upon its face,
and opposite to this recess is fastened the metal diaphragm B by the screws a; C is
a block of metal on the side of the diaphragm opposite to the block A; this block C
is also recessed opposite to the diaphragm, and into this block the screws a pass to
firmly clamp the diaphragm between the blocks A and C. In the block C opposite
to the centre of the diaphragm is an opening into which is fixed the mouth-piece D.
On the back of the diaphragm is suitably secured a block E of carbon, and opposite
to this carbon block is an inclined opening or perforation in the block A elliptical
in section, as shewn in Figure 2, or angular or circular in section, as shown in
Figure 17; in this opening or perforation rests loosely a pin or cylinder F which,
sliding freely in the said inclined opening, is maintained by its weight in contact at its
extremity with the face of the carbon block E. This cylinder must be made of metal or
carbon, or the extremity in contact with the block. E must be of metal or carbon.
An advantageous method of making the cylinder is to use metal for the body of
the said cylinder, or pin and carbon for the tip 6 in contact with the block E, as
shewn in the Drawing. This tip may be attached to the metal body of the pin or
cylinder by spinning a part of the latter around the tip, and it is desirable in order
to obtain as small a surface of contact as possible between the block E and the tip
that the latter should be convex upon its face. The face of the block E may be
parallel with the diaphragm, or it may be inclined at an angle to the diaphragm,
as shown in Figure 15, or convex, as shown in Figure 16.
The block E instead of being made of carbon may be made of metal, or the block
may be dispensed with, and the end of the pin F may rest directly up the surface
upon
of the diaphragm, provided the latter is made of some conducting substance such as
carbon or metal; in some cases, however, it may be desirable to make the diaphragm
of some non-conducting substance.
One pole of a galvanic battery is connected to the metal or carbon part of the
pin F, and the other pole of the said battery is connected to the diaphragm if the
latter is a conductor, or if not to the block E on the diaphragm.
The extremity of the pin therefore forms one electrode of the battery, and the
diaphragm or block the other electrode.
In Figures 1 and 2 the primary coil of an induction-coil G is shewn connected
in this circuit for the reason that an induction-coil is generally used in connection
with a microphone when the latter is used as a transmitter of sounds, the micro-
phone being placed in the circuit of the primary coil, and the telephone, which is
used as the sound-receiver, in the circuit of the secondary coil.
The connection of the pin F with this battery must be of such a character that it
will not interfere with or prevent the free movement of the pin in its inclined
support. This result may be accomplished by the use of a pliable or flexible wire
or other conductor c, as shewn in Figures 1 and 2, for connecting the pin F to a
point in the block A from which a wire passes to the battery, or it may be accom-
plished by connecting this pin to the battery by means of a cup of mercury d, as
shewn in Figure 14. The block A need not be used for clamping the diaphragm
to the block C, and for supporting the pin F, and the diaphragm may be clamped
in any suitable manner and the pin be supported in any manner which will permit
it to slide freely towards the diaphragm by its own weight. H is a metal spring
which at one end is fixed to the block A and at the other end bears upon the
diaphragm; the end of the said spring in contact with the diaphragm is covered

page_text: with soft india rubber. This spring acts as a damper and will not be required when
a diaphragm is used which has but little vibration, as, for instance, one of carbon
or hard wood.
Referring to the microphone or contact-telephone, shewn in Figures 8 and 9, C is
the metal support for the mouth-piece D; this support is provided with an opening
for the insertion of the mouth-piece, and has the diaphragm B secured to it by
screws or in any other suitable manner, a recess being formed between the diaphragm
and the back of the said support C. To the centre of the diaphragm opposite the
mouth-piece is fixed a carbon block E forming one electrode of an electric circuit
and having a smooth surface parallel to the surface of the diaphragm. The other
electrode consists of a piece of carbon b convex and polished upon its face and fixed
in any suitable manner in a metallic cylinder F. This cylinder has attached to it
at right angles by a screw K, or in any other suitable manner, a metal plate I a
little longer and wider than the cylinder F. L is a strip of metal which is attached
at one end to the diaphragm near its elge in any suitable manner, as, for instance,
by a screw M, as shown in the Drawing, and this strip L is inclined outwards from
the diaphragm and is of such length that the edge of the plate I rests upon its free
end. To this strip L near its point of attachment to the diaphragm is attached one
end of a ribbon or band 0 of some flexible conducting material such as metallic foil,
or a metallic web or fabric of cloth, paper, or leather, or some similar flexible
substance metallized or otherwise rendered conducting, and the other end of this
band or ribbon () is attached to the plate I.
Instead of making this band of some flexible material it can be made of rigid
In this
material in two parts, connected by a hinge, as shewn in Figure 13.
manner the desired flexibility will be secured.
The cylinder F and band or ribbon O thus form a pendulum, which has its point of
suspension above the carbon block E, and is prevented from reaching its point of rest
by the contact of the carbon piece with the carbon biock E, and consequently bears
upon the face of said block with a force proportional to the weight of the cylinder
and the distance of the centre of gravity of the pendulum from its point of rest.
This microphone can therefore be adjusted to any desired degree of sensibility,
either by varying the distance of the surface of the carbon block E from the surface
of the diaphragm so as to increase the inclination of the pendulum or by adjusting
a movable weight on the cylinder in such a manner as to vary the distance of the
centre of gravity of the pendulum from the surface of the carbon block E. This
weight may be the screw K.
A convenient manner of effecting this adjustment is shewn in Figures 6 and 7,
in which A is the block which supports the vibrating diaphragm B; E is the fixed
electrode; and S is an elastic plate of metal, which is fixed at one extremity by ŵ
screw M or in any other suitable manner to the top of the block A, anl is free at
its other end. This end is made annular so as to surround the carbon electrode E,
and to this plate the support L of the strip O is attached. A screw M¹ passes
through the lower end of the plate S, and bears upon a piece of soft rubber a, on
the diaphragm B. By means of this screw M¹ the distance of the lower extremity
of the plate S from the vibrating diaphragm can be varied at will, thus changing
the angle of inclination of the movable electrode to the surface of the fixel
electrode.
It is important in a microphone or contact-telephone in order to ensure the clear
transmission of sounds, especially of articulate sounds that the suspended electrode
should be prevented from oscillating from side to side on the fixed electrode or
from having a rotary movement on the same, which result will be accomplished by
holding this suspended electrode in position from at least two points on opposite
sides of its centre of gravity. The object of the band or ribbon for suspending the
cylinder F in the instrument which has been described is for the purpose of
accomplishing this result by preventing the effect of torsion, but the same result
may be accomplished by other means. I do not therefore limit myself to the use
of a ribbon or band for suspending the electrode,

page_text: The support afforded to the plate I, by the end of the strip L, assists in pre-
venting the suspended electrode from rotating or from oscillating from side to side
on the block E.
The electrodes and E, instead of. being made of carbon, can be made of any
conducting substance.
Figure 11 represents a form of microphone or contact-telephone, in which one of
the electrodes 6 is made of platinum, and is attached to a light metallic spring a',
which forms part of the circuit. In this case the pendulons weight rests upon
the electrode b, and the band or ribbon supporting the same need not be a
conductor.
Figure 10 shews a microphone or contact-telephone in which the cylinder F, to
the extremity of which the electrode is fixed, has attached to it a plate of iron or
steel I, which forms the armature of a vertical magnet N, attached to the diaphragm
or to the support for the same. By the use of a second armature the attractive
force of this magnet on the plate I can be varied as may be desired.
Figure 12 shews another form of microphone or contact-telephone in which the
transmission of sounds is obtained by the variation of pressure upon a button of
finely divided carbon enclosed between the diaphragm and the pendulous weight.
In this case also the band or ribbon O need not be a conductor.
The microphone or contact-telephone shewn in Figure 3 is similar in its con-
struction to that shewn in Figures 1 and 2 with the exception that the diaphragm
is made wholly of carbon, though it may be made as in the instrument before
described, and the opening in the block A, for the insertion of the carbon or
metallic pin F. is at right angles to the diaphragm. The instrument is adjusted
for use by dropping the pin into the perforation, and when it has made contact
with the diaphragm by its weight, fixing it in position by a suitable clamping
device, as, for example, the clamp and nut shown in Figure 4.
The improved damper shewn in Figure 5 consists of a ring d¹ of soft india-
rubber or other similar elastic material, which is placed between the diaphragm
and the head of the screw that secures the diaphragm to its support, and is held
against the diaphragm by the said screw. The transmission of sounds by micro-
phones or contact-telephones is improved in clearness by having the electrodes
polished upon the surfaces in contact with one another, and in order that this may
be the case when carbon electrodes are used they are preferably made of a hardened
carbon, which is capable of being polished.
This carbon is prepared from some semi-hard and homogeneous carbon, such as
that from which the pencils used in the production of the electric light are made
by exposing it for about twelve hours in pieces of the size and shape which it is
intended to use in the construction of the electrodes of the microphone to a high
temperature in a retort in which hydro-carbons are being generated, as, for instance,
a retort in which illuminating gas is being made.
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. A microphone or contact-telephone having no rubbing or frictional electric
contact, and having the electrodes maintained in contact with one another, with a
variable pressure by the pressure exerted by a body moving or sliding freely by the
action of gravity at an angle inclined to such contact, substantially as above set
forth and for the purpose specified.
Second. In a microphone or contact-telephone having no frictional or rubbing
electric contact, the combination with a vibrating surface forming one electrode of
a pin forming the opposite electrode, and sliding freely on a suitable support
inclined at an angle to the vibrating surface, and connected to the battery in such
a manner that its free movement on the support will not be interfered with, all
substantially as above set forth and for the purpose specified.
Third. In combination with a vibrating surface forming one electrode the block A
provided with an opening or perforation inclined downwards to the vibrating

page_text: surface, a conducting pin or cylinder having a carbon extremity and sliding freely
in the said inclined opening so as to make contact at its extremity with the
vibrating surface and a connection between said pin and the battery, which will not.
interfere with the free movement of the pin or cylinder, all substantially as above
set forth and for the purpose specified.
Fourth. The combination of the diaphragm, the carbon block E, the damper H,
the block A, the pin sliding freely in an inclined opening in the said block and
the flexible conductor c, substantially as above set forth and for the purpose
specified.
Fifth. A microphone or contact-telephone having only one contact affected by
sound-waves and consisting of two electrodes in contact with one another, which
contact is varied during the transmission of sounds by the variation in the pressure.
upon such contact of a pendulous weight which is kept out of its point of rest by
the interposition of said electrodes, and is supported in such a manner that there is
no lateral movement or pressure between the electrodes, all substantially as above.
set forth and for the purpose specified.
Sixth. In a microphone or contact-telephone the combination of a vibrating
surface forming one electrode, a pendulous weight forming the opposite electrode
with or without a device for changing the inclination of the said weight and a
band or ribbon of flexible material suspending the said weight, which band or
ribbon may or may not be a conductor, substantially as above set forth and for the
purpose specified.
Seventh. In a contact-telephone or microphone the combination of the flexible.
band or hinge and the supporting strip L, substantially as above set forth and
for the purpose specified.
Eighth. In a microphone or contact-telephone the combination of the diaphragm,.
the carbon block E, the carbon tip b, the adjustable weight F, the plate I, the
flexible band O; or hinge and the supporting strip L with or without the frame S
and adjusting screw M¹, substantially as above set forth and for the purpose
specified.
Ninth. A damper (for the diaphragms of telephones or microphones) consisting of
a ring of soft india-rubber or other elastic material held down upon the diaphragm
by a screw passing through said ring, substantially as above set forth and for the
purpose specified.
Tenth. In combination with a diaphragm, of carbon or other meterial forming
one electrode, the self-adjusting opposite electrode capable of sliding into contact
with the diaphragm and of being firmly fixed in position after having adjusted
itself in said contact, substantially as above set forth and for the purpose specified.
Eleventh. In a microphone or contact-telephone having no rubbing or frictional
electrical contact, the combination with a diaphragm forming one electrode of the
opposite non-elastic electrode, capable of sliding freely towards the diaphragm until
both electrodes come into contact with each other, substantially as above set forth
and for the purpose specified.
Twelfth. The combination of two opposite electrodes, one of which has its weight.
so regulated as to exert pressure upon the other, and slides towards the same, and.
is capable of being firmly fixed in position, substantially as above set forth and for-
the purpose specified.
Thirteenth. The combination of the diaphragm, the blocks A and C (the block A.
being provided with a perforation therein at right angles to the diaphragm), the
conducting pin F sliding in the said perforation into contact at its extremity with
the diaphragm, and a device for firmly fixing this pin in position, all substantially
as above set forth and for the purpose.
Fourteenth. In a microphone or contact-telephone an electrode suspended from
and held in position by a permanent magnet, substantially as above set forth and
for the purpose specified.
Fifteenth. In a microphone or contact-telephone a carbon electrode, which is
first formed into the required form and afterwards hardened by being heated in
B

page_text: presence of hydro-carbons, substantially as above set forth and for the purpose
specified.
f
:
Sixteenth. In a microphone or contact-telephone a vibrating surface, forming one
electrode, a damping device bearing against said surface, and a pendulous electrode
in contact with said vibrating surfaces, and suspended from at least two points
which are situated on opposite sides of the centre of gravity of said pendulous
weight, substantially as above set forth and for the purpose specified.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Seventh day of July, in the year of our Lord One
thousand eight hundred and eighty.
W. ROB. LAKE. (L.B.)