IMPROVEMENTS IN TELEPHONES
Year: 1880

page_text: LETTERS PATENT to Joseph Bond Morgan, of Coleman Street, in the
City of London, for an Invention of "IMPROVEMENTS IN TELEPHONES."
A communication from abroad by Thomas Alva Edison, of Menlo Park,
PROVISIONAL SPECIFICATION left by the said Joseph Bond Morgan at the
Office of the Commissioners of Patents on the 8th December 1880.
JOSEPH BOND MORGAN, of Coleman Street, in the City of London.
"IMPROVEMENTS IN TELEPHONES." A. communication from abroad by Thomas
Alva Edison, of Menlo Park, in the State of New Jersey, in the United States
of America.
This Invention relates chiefly to improvements upon the carbon telephone in
respect of which Letters Patent were granted to the said Thomas A. Edison,
dated the Thirtieth July, One thousand eight hundred and seventy seven,
No. 2909, and Fifteenth June, One thousand eight bundred and seventy eight,
No. 2396.
According to one mode of carrying out this Invention a carbon button is secured
to the diaphragm of the telephone, and a weight is employed with a platinized
screw passing through it and resting upon the carbon button.
Bow springs bearing upon the weight and attached to the carbon button serve to
hold the weight in position. The amount of initial pressure may be regulated by
the screw.
The circuit wires are connected to the primary coil of an inductorium
with battery in circuit. Owing to the inertia of the weight, and its not being able
to follow very rapid movements of the diaphragm, there results a difference of
pressure between the screw and the carbon.
The screw may also be tipped with carbon; in fact several thin wafers of carbon
may be used, or a disc or piece of any shape may be used. The weight may be
round, square, half round, oblong, oval, or in any configuration so long as it is a
weight. It may be a hollow sphere cube, or other shape, and be filled with
mercury or any other heavy substance.
The springs may be broad or narrow, and may be bent in any shape between the
weight and disc upon the diaphragm.

page_text: In some cases two pieces of carbon or other finely divided conducting matter are
secured to the diaphragm, each carbon being connected to the circuit. When in a
state of rest the two ends are in contact with each other.
The amount of initial pressure being regulated by the bowing outwardly the
diaphragm by a spring at the outside thereof acted upon by a screw, or two flat
carbons may be employed screwed to the diaphragm and adjusted so that the ends
are in contact, the bowing outwardly and inwardly of the diaphragm from the
normal position tending to increase or decrease the initial pressure.
According to another modification an inertia transmitter is constructed consisting
of a diaphragm having a rubber fixture thereon, a flat or other spring serving to
hold the weight in position, and an adjusting screw whose ends rest upon a carbon
disc. The operation is the same as in the device constructed according to the mode
first herein before described of carrying out this Invention.
A double inertia transmitter may be constructed having two carbons connected
together, hence the difference of pressure takes place at two points. The carbons
in the device first described and in the two latter inertia transmitters may be
fastened to their cups permanently or they may be loose, the latter is preferable.
According to another modification an inertia telephone is constructed in the
following manner :-A diaphragm, carbon button, and rubber standard are
employed with a weight, which is of iron, and is secured to a spring which may be
made adjustable. A permanent magnet is also provided, which may be made to
approach or recede from the weight, and thus increase or decrease the initial pressure
on the carbon.
One of these transmitters may be secured to a diaphragm, which in its turn may
may be pasted to a larger rubber diaphragm.
Another form of inertia transmitter consists of a carbon and a quantity of
mercury both in a tube with an opening through which one of the wires passes, the
whole being secured to the diaphragm.
In another form uprights are secured to the rubber piece which is secured to the
diaphragm; the carbon rests on the platinized surface of a screw, which serves also
to connect the rubber piece with the diaphragm.
A weight is provided, which may be made of a pointed shape, and a spring which
serves to give to the weight an initial pressure and hold it in position; a screw
may be connected from the spring to the point of the weight, and thereby made
adjustable.
A diaphragm with the inertia transmitting devices upon it may be secured to a
wooden case by strings or elastics.
A further variation of this type of transmitter consists of an upright attached to
the diaphragm, the upper end of which upright is platinized and rests upon a carbon
disc which is in an adjustable cup.
The movement of the diaphragm increases and decreases the pressure upon the
carbon. Or the transmitter may consist of a diaphragm and a spring lever which
is given a side motion by the movement of the diaphragm by means of a bevel
piece which connects the lever with the diaphragm. The carbon button against
which the spring rests suitably suspended and closes the circuit; the pressure is
regulated by the movement of the diaphragm.
A double lever may be employed, the carbon being between the two; the bevel
piece serves to separate both levers simultaneously, and they carry their carbon
button with them.
The block connected to the diaphragm may receive a hard carbon rod against
which the springs rest; they are bevelled, any outward movement of the diaphragm
tending to increase the pressure. A carbon wheel may be used in lieu of the rod
and between double springs.
According to a further modification, an inertia telephone is constructed with two
carbons connected together, and resting on these carbous is a weight which is kept
upon them by a spring around an insulating rod, a nut being provided for
increasing or decreasing the tension of the spring. Or the diaphragm may have a

page_text: block to which is secured a carbon, whilst on the latter rests two springs, the
forward movement of the diaphragm increasing the pressure at both points of
contact. Or a cup may be employed with a carbon rod in it, whilst upon the
carbon rests a lever, the initial pressure of which may be varied by an electro-
magnet, which may be the primary coil of the inductorium or disconnected
therefrom, or it may be a permanent magnet, or even a spiral or flat spring may
be used, or if the diaphragm is held in the right position its own weight may be
used.
Another modification consists of an upright in the base of which is the carbon ; on
this rests a weight, a hole being drilled through it into which passes the rod around
which the adjusting spring is coiled, this serves to hold the weight in position; by
means of a nut the initial pressure may be regulated.
Or the carbon connected to the diaphragm may be acted upon by a pendulous
spring with carbon tips upon its extremity resting against the carbon, a weight
being also employed.
According to a further modification of inertia transmitter, weights are secured to
a lever pivotted from an arm which connects with a diaphragm; the centre of this
lever rests upon a carbon button in a cup upon the diaphragm; one of the weights
is adjustable so as to adjust the initial pressure.
Or four springs may be used secured to an insulating block upon the diaphragm;
the current enters via the first spring, thence passes through its carbon tips to
the carbon tips of the second, third, and fourth springs, and out by the fourth
spring.
According to another part of this Invention a receiver is constructed upon the
electro motograph principle in the following manner :-It consists of a diaphragm,
a disc of chalk or other inert substance saturated with phosphate of soda or other
proper chemical, to produce the motograph action, and a spring connecting the
diaphragm with the disc tipped with palladium.
The shaft of the disc is rotated by a worm and worm wheel.
An inertia telephone may be secured to a strip of elastic material instead of a
diaphragm; it is held against its case by springs which are tipped with rubber or
other soft substance.
The motograph receiver may be arranged as a transmitter, the same consisting of
a diaphragm, a spring connecting the same with the chalk; the chalk in this case is
not rotated.
This apparatus is included in a primary circuit of an induction coil having a high
resistance; a battery is provided; a magneto receiver may be used or a receiver an
exact copy of the transmitter.
The action is as follows:-
When the diaphragm is vibrated by the voice it sets in motion the spring, this
instantly depolarizes the point of contact between it and the chalk, thus increasing
the flow of current from the battery; the instant the spring comes to rest it polarizes
and weakens the current from the battery,
The motograph may also be arranged to transmit direct from one to the other
without the intervention of an induction coil, also arranged so that they can by
raising a lever be made receivers or transmitters. A rubber presser is used to press
the spring from the diaphragm down upon the chalk when receiving; the lever is
provided with a handle and limiting stops are also used. A spring is further
provided, also a roller, which serves to hold the lever when it is drawn up or down ;
both instruments are similar in construction. When receiving, the pressure is put
on the spring resting upon the chalk and it is rotated, but when transmitting the
pressure on the spring is light and the chalk is not rotated.
The telephone may further be constructed so that each sound wave is made of
an aggregation of smaller waves.
A lever is provided suitably pivotted, and near its fulcrum is an arm connecting it
with the diaphragm. One end of the lever rests lightly upon a block of finely divided
conducting inatter, which block is connected to one part of the circuit, whilst the lever

page_text: is connected to the other part; the vibration of the diaphragm serves to reciprocate
the lever or spring over the surface of the block. I provide a push button arranged
to open the receiver circuit when transmitting, and, vice versa, open the transmitting
circuit when receiving, thus preventing the tertiary or primary coils of the
inductorium from short circuiting each other's currents.
When the lever of the push key is up, the tertiary coil is connected through the
primary with the receiver; when down, the carbon transmitter is connected in
circuit and the tertiary circuit broken. The two chemical receivers may be situate
in the main line with a condenser, the latter to prevent the circulation of earth
currents through the chalk and thus deteriorate them.
The tertiary coils are thus dispensed with.
I may mention that sticks, buttons, or discs of finely divided conducting matter,
may be made of the following named materials:-Carbon, lamp black, anthracite
coal, bog coal, cannel coal, bituminous coal, retort carbon, carres carbon, coke
carbon, carbon from charring organic matter, amorphous carbon, charred diamond
charcoal from organic matter, graphite, plumbago, blacklead, carburet of iron, and
other carburets of the metals, metallized carbon, metallized graphite, metallized
blacklead, metallized lamp black, peroxide lead, peroxide manganese, iodide copper,
sulphide tin, sulphide iron, sulphide copper, sulphide antimony, sulphide nickel,
sulphide cobalt, chalcopyrite pyrites, sulphide bismuth, sulphide lead, galena,
plumbic sulphides, sulphide chromium, sulphide mercury, and all the conducting
sulphides, also powdered platinum, phodium, rutheum, palladium, iridium, tin,
copper, lead, zinc, iron, chromium, titanium, aluminium, antimony, arsenic, barium,
bismuth, borax, codium, calcium, carium, cobalt, columbium, didynium, eubium,
glucinum, gold, lanthanium, lithium, magnesium, manganese, mercury, malybdinium,
nickel, mobium, norium, pelopium, amorphous phosphorus, selenium, silicon, silver,
sodium, stratium, tellurum, terbium, thornum, tungsten, uranium, vanadium,.
ythrium, zinc, zirconium, magnetic oxide of iron, daryium, gallium.
Any known substance which conducts electricity, and which can be powdered,
may be moulded by itself, or mixed with one or more other conducting or
nonconducting substance to form the tension regulator for a telephone.
For making the case of the telephone, any known wood, metal, or manufactured
or native substance may be used.

page_text: "
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Joseph Bond Morgan in the Great Seal Patent Office on the
8th June 1881.
JOSEPH BOND MORGAN, of Coleman Street, in the City of London.
IMPROVEMENTS IN TELEPHONES." A communication from abroad by Thomas
Alva Edison, of Menlo Park, in the State of New Jersey, United States of
America.
This Invention relates chiefly to improvements upon the carbon telephone, in
respect of which Letters Patent were granted to the said Thomas Alva Edison,
dated the 30th day of July 1877, No. 2909, and 15 day of June 1878, No. 2396.
In telephones heretofore made use of the electric current has passed through
carbon, or similar material having inferior conducting properties, and the movement
of the diaphragm as it responds to the atmospheric vibrations has applied more or
less pressure of the metallic electrodes against such carbon, and the electric current
on the line has thereby been varied so that at the distant station the current
acting in an electro-magnet has given corresponding movements to the diaphragm
of the receiving instrument.
The object of the present Invention is to allow the diaphragm to respond to the
atmospheric vibrations without being unduly checked, and at the same time to
ensure the necessary pressure and extent of surface contact between the carbon or
similar material and the electrodes to produce the corresponding electric changes or
undulations in the line.
In the Drawings the present improvements are shown in some of the various
forms which have been availed of for use in transmitting articulate speech. In
these Figures the diaphragm is represented at a with a suitable case b and mouth
piece c, the diaphragm a resting upon or being secured at its edges to the said
case b. The carbon or similar material for. regulating the electric condition of the
line is shown at i.
In the sectional plan, Fig. 1, the carbon i is in a cup d of insulating material,
such as hard rubber. One metallic electrode e is in the form of a metal rivet that
holds the cup d to the diaphragm, the carbon rests against this. The other
electrode is in the form of a platina disk at the end of the screw f that passes
through the spring g that is connected at its ends to the cup d so that the proper
initial pressure is applied to the carbon by the screw. There is a weight h carried
by the spring, and one wire k is connected to the diaphragm, and the other wire
to the spring g. The vibrations of the diaphragm produced by speech or other
sounds act upon the atmosphere and vary the electric condition of the circuit
passing to the distant instrument in consequence of the weight h acting by its
inertia to vary the pressure on the carbon. When the pressure is the greatest the
resistance will be the least, and the electric current will flow most freely; and
when the pressure is less the surface contact with the carbon will be less, and the
electric current will be diminished in proportion. This mode of operation holds
good in all the telephone instruments herein described where the carbon is between
a weight and the diaphragm, the former acting by its inertia to vary the pressure
on the carbon.
Owing to the inertia of the weight, and its not being able to follow any rapid
movements of the diaphragm, there results a difference of pressure between the
electrodes and the carbon. The screw or electrodes may also be tipped with
carbon, in fact several thin wafers of carbon may be used, or a disk or piece of any
shape may be used. The weight may be round, square, half round, oblong, oval,

page_text: or in any configuration so long as it is a weight. It may be a hollow sphere, tube,
or other shape, and be filled with mercury or any other heavy substance.
The spring g may be broad or narrow, and may be bent in any shape between
the weight and disk upon the diaphragm.
The circuit wires may be connected to the primary coil of an inductorium with
battery in circuit.
Fig. 2 is the same as Fig. 1, only the spring g is nearly straight instead of being
elliptical. In Fig. 3 the adjusting screw f is made to act upon a magnet that
varies the initial pressure upon the carbon by its proximity to the weight h, which
is to be of iron. The closer the pole of the magnet is to the iron weight the more
the attraction will be to draw the weight from the carbon, and lessen the pressure
exerted by the spring g that carries the weight, and the vice versa.
In Fig. 4 two weights h with separate springs g are shown acting upon separate
pieces of carbon. The current passes from k through one spring and weight,
through the first carbon and the electrode connected to the diaphragm, and back
through the other electrode e, and carbon weight and spring to the other wire of
the circuit; the operation is as before set forth. The pressure of the springs and
weights on the carbons will be varied by the screws that attach the springs to the
cups or arms d.
In Fig. 5 the weight h is sustained by the spring g that is supported upon arms
that intervene between the ends of the spring and the cup d; otherwise it is
similar to the device shown in Fig. 1.
Fig. 6 represents the inertia transmitter as upon a small diaphragm a, and this
is secured by adhesive material to a larger diaphragm a', which may be of stretched
india rubber or other suitable material. The inertia of the weight causes the
variations in pressure upon the carbon as the parts are vibrated by the sound
waves acting on the diaphragm a¹.
When a diaphragm is fastened at its edges and vibrated by the action of the
sound waves in the atmosphere it becomes alternately convex and concave to a very
slight extent. This is availed of to produce more or less pressure between two
pieces of carbon i, Figs. 7 & 8, that are fastened upon the diaphragm, and their
faces touch each other. The circuit wires k, l, are connected to the clamping
devices of the respective pieces of carbon. The spring 6¹ and set screw b² serve to
apply more or less yielding pressure to the diaphragm, and bow the same, and
regulate the initial pressure of one carbon against the other.
By placing the carbon i, Fig. 9, against an arm n that is platinized at the point
of contact the vibrations of the diaphragm and its change of shape vary the
pressure of the arm upon the carbon, and produce rise and fall of electric tension
as aforesaid.
The same effect is produced when the carbon i, Fig. 10, is between two spring
arms n, n', and there is a double wedge shaped projection o on the diaphragm that
acts to spread the springs or allow them to approach closer as the diaphragm a
and wedge o vibrate, and thereby the pressure on the carbon is varied.
A single incline o, Fig. 11, may be employed with a spring n to act as aforesaid.
In this case the stock p that carries the spring and carbon is to be adjusted by the
screw to vary the position of the parts to the incline, and the consequent initial
pressure of the spring upon the carbon.
In Fig. 12 the carbon is in a cup that is adjusted by the screw f, and the
incline o acts upon a spring arm n that bears against the carbon.
In Figs. 13 and 14 the carbon i is in the form of a small rod passed through a
stud upon the diaphragm. In Figure 13, spring arms n, n¹, with inclined ends
similar to those in Fig. 10, bear upon the carbon; the ends of these arms should be
of platina or similar metal that is not injured by the electric action; this is also to
be the case in all the electrodes that bear on the carbon.
In Fig. 14 the spring arms g bear directly on the carbon, and the weights h are
comparatively small; the action in both Figs. 13 & 14 is the same as before

page_text: described, except that the motion of the diaphragm and carbon against the spring
arms varies the electric tension of the line.
In Figs. 15 and 16 the carbon is in the form of a roller i, bearing against the
inclined ends of the springs. In Fig. 15 only one spring n is shown, in Fig. 16
there are two springs n, n¹.
In Fig. 17 the weight 1, carbon i, and cup d are similar to those in Fig. 1, but
the spring g is helical, and its back end supported by an arm.
In Fig. 18 there are two carbons i, against which the weight h and spring g act,
and the circuit is through the carbons, the wires being connected to a piece of
platina in each recess that holds one of the carbons. In these Figs. 17 & 18
there is a hole in each weight for the rod e² to pass through, which rod holds the
weight in position.
Instead of the diaphragm resting at its edges upon the case it may be suspended
by cords or wires 1, 2, 3, 4, shown in Fig. 19. It is preferable to use cords
of india rubber to prevent the diaphragm continuing to vibrate, and transmit
incorrect electric pulsations after the atmospheric sound waves have ceased.
The same effect is produced by spring fingers tipped with rubber bearing against
the diaphragm, as shown at b, Fig. 20. In this instance the circuit regulator and
inertia transmitter are shown upon a strip, it not being necessary to employ a
round diaphragm.
In Fig. 21 a magnet 6 is represented for applying the initial pressure to the
carbon; this magnet acts through a lever upon the carbon i. The circuit of this
electro magnet may pass through the primary of the inductorium, or the lever may
be provided with weights h, as in Fig. 22, one of which weights may be adjustable,
so as to apply the proper pressure to the diaphragm.
When the carbon is placed at one end of a tube c³, as in Fig. 23, and mercury
placed in the other part of the tube, the operation will be the same as before
described, the mercury forming a resistance, and by its inertia varying the pressure
of the electrodes on the carbon i.
In some cases three or four springs 13 are secured in an insulating block upon
the diaphragm, as in Fig. 24, each spring having a block of hard carbon i at its
end. The circuit wires are connected to the first and last springs, and the varying
pressure of the carbons against each other as the diaphragm is vibrated causes the
rise and fall of tension in the circuit corresponding to the air waves acting on the
diaphragm.
In Figure 25 there are two carbons i, one fastened to the diaphragm, the other
to the spring g, and there may be a weight to act by inertia to cause the carbons
to press against each other with greater or less force, as the diaphragm is vibrated
by the words spoken.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein before in part
recited Letters Patent is,-
First. In a telephone instrument the combination with the diaphragm and
carbon or similar material in the electric circuit of the weight or inertia resistance
to vary the electric current in proportion to the vibrations of the diaphragm,
substantially as set forth.
Second. The combination with the diaphragm and carbon or similar material of
a lever and a magnet to vary the initial pressure upon the carbon, substantially as
set forth.
Third. The combination with the weight and the diaphragm of two pieces of
carbon or similar material in the electric circuit, and against which the weight acts,
substantially as set forth.
Fourth. The combination with the diaphragm and carbon or similar material in
the electric circuit of an incline that serves to vary the pressure on the carbon as
the parts are moved by the diaphragm, as set forth.

page_text: Fifth. The combination with the weight and carbon of a diaphragm that is loose
at its edges, and held by yielding supports, as set forth.
Sixth. The combination with the diaphragm of two pieces of carbon in contact
with each other circuit connections and means for keeping the surfaces of the
carbons in contact, as specified.
In witness whereof, I, the said Joseph Bond Morgan, have to this my
Specification set my hand and seal, this Seventh day of June, One thousand
eight hundred and eighty one.
JOSEPH BOND MORGAN. (L.S.)