IMPROVEMENTS IN ELECTRIC TELEPHONY (TRANSMITTING OR CAUSING SOUNDS FOR TELEGRAPHING MESSAGES) AND TELEPHONIC APPARATUS
Year: 1876

page_text: LETTERS PATENT to William Morgan-Brown, of the Firm of Brandon and
Morgan-Brown, Engineers and Patent Agents, of 38, Southampton Buildings,
London, and 1, Rue Laffitte, Paris, for the Invention of "IMPROVEMENTS IN
ELECTRIC TELEPHONY (TRANSMITTING OR CAUSING SOUNDS FOR TELEGRAPHING
MESSAGES) AND TELEPHONIC APPARATUS." A communication from abroad by
Alexander Graham Bell, of the University of Boston, Massachusetts, United
States of America, Professor of Vocal Physiology."
"
PROVISIONAL SPECIFICATION left by the said William Morgan-Brown at
the Office of the Commissioners of Patents on the 9th December 1876.
WILLIAM MORGAN-BROWN, of the Firm of Brandon and Morgan-Brown; Engineers
and Patent Agents, of 38, Southampton Buildings, London, and 1, Rue Laffite, Paris.
IMPROVEMENTS IN ELECTRIC TELEPHONY (TRANSMITTING OR CAUSING SOUNDS FOR
TELEGRAPHING MESSAGES) AND TELEPHONIC APPARATUS."
In all previous systems. of telegraphy, messages have been received either by
means of chemical changes produced by the action of the electrical current, as in
the various forms of automatic and autographical telegraphs, or by means of the
mechanical movement of a portion of the receiving instrument operating to produce
a visible signal, as in needle telegraphs, a mark upon paper or other material, as in
printing telegraphs, or a sound, as in the Morse system. Upon these and all other
plans it has been found difficult, if not impossible, to distinguish between more than
four messages transmitted simultaneously over the same circuit, two in each
direction.
.
This present Invention relates to the reproduction by the necessary receiving
instruments of any particular sounds or combination of sounds through the agency
of an electric current, whereby a multiplicity of telegraphic messages may be sent
simultaneously over a single circuit in the same or in opposite directions and
received without confusion, and whereby articulate speech may be electrically
transmitted.
- The first part of the Invention relates to the. production or transmission of
musical notes by means of intermittent impulses of votaic electricity, and to the

page_text: utilization of such musical notes as telegraphic signals, whereby two or more tele-
graphic messages can be sent simultaneously in the same direction over a single
circuit.
The second part of the Invention relates to the production or transmission of
musical notes by means of intermittent impulses of induced electricity, whereby
two or more telegraphic signals or messages can be sent simultaneously over a single
circuit in the same or in opposite directions.
The third part of the Invention relates to the production or transmission of
musical notes by means of undulatory currents of electricity, one battery being used
for the whole circuit, whereby two or more telegraphic signals or messages can be
transmitted simultaneously over a single circuit in the same or in opposite
directions.
The fourth part of the Invention relates to the electrical production or trans-
mission of sounds of every kind by means of undulatory currents of electricity,
whereby not only musical sounds but articulate speech can be transmitted over a
telegraph line, and two or more messages be simultaneously sent over a single
circuit in the same or in opposite directions.
The fifth part of the Invention relates to the electrical production or trans-
mission of sounds of every kind, without a battery, by means of undulatory
currents of electricity, whereby not only the musical notes but articulate speech
- can be transmitted over a telegraph line, and two or more messages be sent simul-
taneously over a single circuit in the same or in opposite directions.
The sixth part of the Invention relates to the automatic reception of signals or
messages by introducing at the receiving end of the line a local circuit containing
a vibratory circuit breaker, whereby telephonic signals or messages may be auto-
matically recorded.
The seventh part of the Invention relates to the application of electric telephony
to autographic telegraphy, whereby characters or marks of any description may
be copied in fac simile at the receiving end of the line.
FIRST PLAN.
The first part of the Invention (illustrated in Figures 1 and 2 of Sheet 1, and
Figures 3, 4, and 6, of Sheet 2) consists of a method of and apparatus for trans-
mitting two or more telegraphic messages or signals simultaneously along a single
wire by the employment of transmitting instruments, each of which occasions &
succession of electrical impulses differing in rate from the others; and of receiving
instruments each tuned to a pitch at which it will be put in vibration to produce
its fundamental note by one only of the transmitting instruments.
The transmitting instrument T (Figure 1) consists of an electro-magnet e having
& steel spring armature a, which is kept in continuous vibration by the action of
a local battery b; the armature a in the course of its vibration brings the platinum
rivetr alternately into contact with two platinum points land m, one, 1, being placed
in a local circuit b, s², e, l, r, s³, b, and the other, 'm, communicating with the line
wire W through the screw cap a¹.
.
The receiving instrument R, shewn in plan in Figure 1, and in elevation in
Figure 2, consists of an electro-magnet E, having a coil upon only one of its legs.
A steel spring armature A is firmly clamped by one extremity to the uncovered leg
of the electro-magnet E, and its free end is allowed to project above the pole of
the covered leg. Upon depressing the key K (Figure 1) a communication is
established between the main battery B and the vibrating armature a of the
transmitter T. When the rivet touches the point m the main circuit_is com-
pleted, the currents of 2 passed to the ground at G, and the currents of c pass
through K, 8, 7, m, s, to the line wire W, and thence through the electro-magnet E
of the receiver R to the ground at G. When the rivet r leaves the point m the
main circuit is broken. So long then as the key K is depressed the vibration of a
occasions an intermittent action of the current from the battery B upon the line

page_text: wire W, and the armature A of the receiver R is attracted in an intermittant
manner by its electro-magnet E.
When the makes and breaks of the circuit at m, r, are timed to the normal
movements of the armature A of the receiving instrument, that is, when A is tuned
to yield the same musical pitch as the armature a of the transmitting instrument,
then the armature A is thrown into strong vibration, thereby causing it to emit
its musical note.
When the key K is raised the communication between the main battery B and
the transmitter T is cut off, and A becomes silent. So long as the key K is
depressed a musical note is emitted by A, and the duration of this note can be made
to signify the dot or dash of the Morse alphabet. Thus a telegraphic despatch can
be sent from T to R by manipulating the key K in the usual manner.
Figures 3, 4, and 5, Sheet 2, illustrate the combination of these instruments upon
a telegraphic circuit, so as to permit of the simultaneous transmission of a number
of telegraphic messages along a single wire.
The armatures of the transmitters and receivers that are numbered alike at all
the stations have the same pitch. Thus the transmitter T of Figure 3 is the unison
of the transmitter T at the station represented in Figure 4, and also of the
receiver R2 at the stations shewn in Figures 3, 4, and 5.
The sounds produced by the transmitters T, T¹, T, &c., differ in pitch from one
another, and are so arranged that each transmitter can affect one and one only of
the receiving instruments R, R¹, R, &c., at each station upon the line.
To illustrate the operation of this form of the Invention depress any key, say,
key K, Figure 3, a communication being thereby established between the main
battery B and the transmitting instrument T', an intermittent current passes on to
the main line through the receiving instruments R, R¹, R³, &c., of Figures 3, 4,
and 5, to the earth at G, Figure 5. The receiving instruments R¹, Figures 3, 4,
and 5, respond so long as the key K¹, Figure 3, is depressed, and become silent
the moment it is raised. The other instruments R, R³, &c., at stations Figures 3, 4,
and 5, remain silent, so that a telegraphic message transmitted by the manipulation
of key K', Figure 3, is received upon only its corresponding receiving instrument
at each station toward that station herein shown as Figure 5, where the receiving
instruments are connected directly with the earth.
The instruments shewn in Figure 4 operate, as just described, for those of
Figure 3, the depression of each key K, K³, or K³, &c., operating those receiving
instruments in stations 4 and 5 that are in unison with the transmitting instrument
connected with the key, but does not affect the instruments in Figure 3, or in that
direction.
To illustrate the simultaneous transmission of telegraphic messages by these
instruments an operator in the station, shown in Figure 3, is supposed to manipulate
the key K, while at the same time another operator in station Figure 4 is trans-
mitting an entirely different despatch by the manipulation of the key K¹. The
signals produced by the depression of key K, Figure 3, are received by the
receivers R of Figures 3, 4, and 5, and the signals due to the manipulation of the
key K, Figure 4, affect the receiving, instrument R¹ of Figures 4 and 5, but
not R' of Figure 3, or of any station in the direction of Figure 3, hence, although
upon this plan two or more messages may be sent simultaneously over the same
circuit from the same or different stations to the same or different stations, still
as the signals pass only in one direction two line wires are required to complete
communication in both directions. Intermittent currents adapted to work these
instruments may be produced without actually making and breaking the circuit,
as herein-before described, by suddenly increasing and diminishing the intensity
of the current. Such currents are termed for the sake of distinction "pulsatory."
Intermittent and pulsatory currents may be of two kinds, accordingly as the
electrical impulses have all the same polarity, or are alternately positive and
negative; in the former case they are termed "direct," in the latter "reversed"
currents. These distinctions are graphically illustrated in Figures 6 and 7.

page_text: In the methods heretofore described employing intermittent currents of electricity
the limit to the number of signals that can be sent simultaneously over the same
wire is very speedily reached; for when a number of transmitting instruments
having different rates of vibration are simultaneously making and breaking the
same circuit, the effect upon the main line is practically equivalent to one continuous
current; in addition to this objection local and main batteries are required at every
station on the line. Similar difficulties are, experienced in employing pulsatory
currents; to obviate these difficulties, the plan of using an undulatory current of
electricity as described in this third part of the Invention was devised.
It has long been known that when a permanent magnet is caused to approach
the pole of an electro-magnet, a current of electricity is induced in the coils of the
latter, and that when it is made to recede a current of opposite polarity to the first
appears upon the wire. When, therefore; a permanent magnet is caused to vibrate
in front of the pole of an electro-magnet, an undulatory current of electricity is
induced in the coils of the electro-magnet, the undulations of which correspond in
rapidity of succession to the vibrations of the magnet in polarity to the direction of
its motion, and in intensity to the amplitude of its vibration, or rather to the
velocity of its motion. A current of this character is graphically represented in
line 3, Figure 7, Sheet 1. When the permanent magnet is caused to vibrate in
front of the pole of an electro-magnet which is placed in circuit with a voltaic
battery, the undulatory current induced by the vibration of the permanent magnet
is superposed upon the voltaic current. When the induced impulse is of similar
polarity to the voltaic current it serves to strengthen the intensity of the latter,
but when it is of opposite polarity it tends to neutralize the voltaic current. In
´ such an arrangement the resultant effect of the vibration of the permanent magnet
is to throw the battery current into waves, as in line 3, Figure 6, by alternaterly
increasing and diminishing the intensity of the current. Such increase and
diminution in the intensity of the current does not take place with the suddenness
characteristic of a pulsatory current (see line 2, Figure 6), but is proportional to the
increase and diminution of the density of the air during the vibration of the
inducing body.
The various kinds of electrical currents denominated intermittent, pulsatory, and
undulatory, are graphically represented in Figures 6 and 7. In Figure 6 the
currents are direct, that is, the electrical impulses 63, 6², b², &c., are all of the same
polarity, either positive or negative, and in Figure 7 the currents are "reversed,”
That is, the electrical impulses are alternately positive and negative.
Direct Intermittent Current (shewn in line 1, Figure 6).-The impulses b³, b³, &c..
are all of positive or all of negative electricity, and the vertical thickness of the

page_text: lines 62, 63, &c., measured from the zero line 1, 21, represents the intensity of the
current at the part observed. The horizontal extention of the line 6 indicates the
duration of the electrical impulse, and the horizontal extention of the space f* shews
the length of time the current is absent from the circuit.
Reversed Intermittent Current (shewn in line 1, Figure 7).-Impulses of positive
electricity are represented above, and impulses of negative electricity below the
zero line 2, 2, and the impulses 6², d², are respectively positive and negative, or
vice versa.
Direct Pulsatory Current (shewn in line 2, Figure 6).-The current of electricity
represented is continuous, but it changes suddenly in intensity, the elevations b³, b, &c.,
indicating the impulses of maximum intensity, and the depressions c³, c, the
impulses of minimum intensity. As before, the vertical thickness of the line
indicates the strength of the current.
.
Reversed Pulsatory Current (shewn in line 2, Figure 7).-The impulses 6³, d³, are
alternately positive and negative without any break in the continuity of the
current.
Direct Undulatory Current (shewn in line 3, Figure 6).-As before, the vertical
thickness of the line represents the strength of the current, the elevations 62, 63, &c.,
express-the impulses of maximum intensity, and c³, c³, &c., those of minimum
intensity. The changes of intensity, as illustrated in line 3, do not occur with the
suddenness characteristic of pulsatory currents, as shewn in line 2, but are
proportional to the changes in the density of the air during the.production of a
sound.
Reversed Undulatory Current (shewn in line 3, Figure 7).-The elevations bª,
6, &c., indicate impulses of positive, and the depressions d², d, impulses of negative
electricity, the vertical thickness of the portions b³, d², indicating the intensity of
the positive or negative impulse at the part observed. The oscillations of the
current above and below the zero line correspond to the increase and diminution of
the density of the air during the production of a sound, hence the elevations b², 6*, &c.,
correspond to condensations of air, and the depressions d³, d³, &c., to rarefactions, the
intensity of the positive or negative impulses being proportioned to the degree of
density or rarity of the air.
The differences between intermittent pulsatory and undulatory currents will be
more clearly understood by describing and illustrating the condition of the electrical
current when the attempt is made to transmit two musical notes simultaneously,
first upon one plan and then upon the others, let the interval between the two
sounds be a major third; then their rates of vibration are in the ratio of 4 to 5.
Now, when an intermittent current is used, the circuit is made and broken 4
times by the armature a, Figure 11, Sheet 1, of one transmitting instrument in the
same time that 5 makes and breaks are caused by the armature a¹ of the other
transmitting instrument. A and B, Figure 11, represent the intermittent currents
produced, four impulses of B' being made in the same time as five impulses of A³;
6, 6, &c., Figure 11, shew where and for how long a time the circuit is made, and
ff, &c., indicate the duration of the breaks of the circuit. The line A³ + B* shews
the total effect.upon the current when the armatures a, a¹, Figure 11, are caused
simultaneously to make and break the same circuit, and the combined effect upon
the current passing through the receiver R, shewn at A* + B*, Figure 11, is very
nearly equivalent to a continuos current.
When many transmitting instruments of different rates of vibration are simul-
taneously making and breaking the same circuit the current. upon the main line
become for all practical purposes continuos.
When the armatures a, a, are arranged upon circuit, as shewn in Figure 12,
pulsatory currents traverse the coils of the receiving instrument R. The line AÍ
represents the pulsatory current due to the action of one armature a; and the
line B, the action due to the other armature a¹; 6³, b³, &c., represent impulses of
maximum intensity; and c³, c³, &c., impulses of minimum intensity. Four impulses
of B² are made in the same time as five impulses of A, and the line A² ‍+ Bª.

page_text: represents the total effect upon the current passing through the coils of the receiver
R, when the armatures a and a¹ are caused to vibrate simultaneously. This effect
is nearly equivalent to a continuous current of minimum intensity. .
Next, consider the effect when undulatory currents are employed. Electrical
undulations induced by the vibration of a body M, Figure 13, capable of inductive
action, can be represented graphically by the same sinusoidal curve which expresses
the vibration of the inducing body itself, for, as above stated, the rate of oscillation
in the electrical current is the same as that of the inducing body. The intensity of
each induced impulse is proportional to the velocity of the motion of the inducing
body, and the polarity of each induced impulse depends upon the direction of the
motion of the inducing body to or from the pole of its electro-magnet. The
sinusoidal curves A and B, Figure 13, represent graphically the electrical undula-
tions induced in a circuit by the vibration of permanent magnets M and M³ or other
bodies capable of inductive action.
The portions 62, 63, &c., represent impulses of positive electricity; and d³, d³, &c.,
impulses of negative electricity. The horizontal line s¹, 2, represents the zero of
current, and the vertical distance of any portion of the curve 6 or d from the zero
line expresses the intensity of the positive or negative impulse at the part
observed.
The vibrations represented by the sinusoidal curves B and A
the ratio aforesaid of four to five; that is, four oscillations of B
same line as five oscillations of A².
Figure 13, are in
are made in the
The combined effect of A and B when induced simultaneously on the same
circuit is expressed by the curve A³ + B³, Figure 13, which is the algebraical sum
of the sinusoidal curves A and B. In Figure 14 the permanent magnets M and
Mare caused to vibrate in front of the poles of electro-magnets e, e¹, placed in
circuit with a battery B. By such an arrangement the battery current is thrown
into waves. The lines A2, B, represent the undulatory currents produced respect-
ively by the vibrations of M and M³, and as in the instances four impulses
of B are made in the same time as five impulses of A, the elevations b, b²,
indicate impulses of maximum intensity, and the depressions c³, c³, &c., impulses
of minimum intensity. The vertical distance of any portion of the curve b³, c²,
from the zero line 21, 1, expresses the intensity of the current at the part
observed. The line A + B' expresses the resultant effect upon the current
when the permanent magnets M, M³, are caused to simultaneously vibrate.
The curves A + B*, Figures 13 and 14, also indicate the actual motion of the
air when the two magnets M, M², are vibrated simultaneously. Thus, when
electrical undulations of different rates are simultaneously produced upon the same
circuit the effect is exactly analogous to that occasioned in the air by the vibration
of the inducing bodies; hence the co-existence upon a telegraphic circuit of
electrical undulations corresponding to sounds of different pitch is manifested, not
by the obliteration of the vibratory character of the current, as with intermittent
and pulsatory current, but by peculiarities in the shapes of the electrical undula-
tions, or in other words, by peculiarities in the shapes of the curves which represent
those undulations.
There are many ways of producing undulatory currents of electricity dependent
for effect upon the vibration or motion of bodies capable of inductive action. A
few of the methods that may be employed are as follows:-When a wire, through
which a continuous current of electricity is passing, is caused to vibrate in the
neighbourhood of another wire an undulatory current of electricity is induced in
the latter. When a cylinder, upon which are arranged bar magnets, is made to
rotate in front of the pole of an electro-magnet an undulatory current of electricity
is. induced in the coils of the alectro-magnet.
Undulations are caused in a voltaic current by the vibration or motion of bodies
capable of inductive action, or by the vibration of the conducting wire itself in the
neighbourhood of such bodies. Electrical undulations may also be caused by
alternately increasing and diminishing the resistance of the circuit or by alternately

page_text: increasing and diminishing the power of the battery. The internal resistance of a
battery is diminished by bringing the voltaic elements nearer together, and
increased by placing them farther apart. The reciprocal vibration of the elements
of a battery therefore occasions an undulatory action in the voltaic current.
The external resistance may also be varied; for instance, let water or some
other liquid of high resistance form part of a voltaic circuit, then the more deeply
the conducting wire is immersed in the water or other liquid the less resistance does
the liquid offer to the passage of the current. Thence the vibration of the conduct-
ing wire in water or other liquid included in the circuit occasions undulations in
the current. The vertical vibration of the elements of a battery in the liquid in
which they are imursed produces an undulatory action in the current by alternately
increasing and diminishing the power of the battery.
In illustration of one method of creating electrical undulations a form of
apparatus is shewn in Figure 15. It is preferable to employ for this purpose an
electro-magnet E, Figure 15, having a coil upon only one of its legs. A steel
spring armature A is firmly clamped by one extremity to the uncovered leg h of
the magnet, and its free end is allowed to project above the pole of the covered leg.
The armature A can be set in vibration in a variety of ways, one of which is by
wind, and in vibrating it produces a musical note of a certain definite pitch.
When the electro-magnet E is placed in a voltaic circuit B, E, W, E¹, B, the
armature A becomes magnetic, and the polarity of its free end is opposed to that of
the magnet underneath. So long as the armature A remains at rest no effect is
produced upon the voltaic current, but the moment it is set in vibration to produce
its musical note, a powerful inductive action takes place, and electrical undulations
traverse the circuit above described. The undulatory current passing through the
coil of the electro-magnet El causes vibration in its armature A when the armatures
of the two magnets are normally in unison with one another, but the armature A¹
is unaffected by the passage of the undulatory current when the pitches of the two
armatures are different.
The instruments shown in Figure 15 are like in plan to the receiving instruments
R, R, &c., of Figures 1, 2, 3, 4, 5, 8, 9, 10. A number of instruments may be
placed upon a telegraphic circuit, as in Figures 16, 17, 18. When the armature of
any one of the instruments is set in vibration all the other instruments upon the
circuit, which are in unison with it, respond, but those which have normally a
different rate of vibration remain silent. Thus, if R, Figure 16, is set in vibration,
the armature of the receivers R, Figures 17, 18, vibrate also, but all the others on
the circuit remain atill; so if R', Figure 17, is caused to emite its musical note the
instruments R¹, shewn in Figures 16 and 18, respond. They continue sounding so
long as the mechanical vibration of R¹, Figure 17, is continued, but becomes silent
with the cessation of its motion. The duration of the sound may be used to
indicate the dot or dash of the Morse alphabet, and thus a telegraphic dispatch may.
be indicated by älternately interrupting and renewing the sound.
When two or more instruments of different pitch are simultaneously caused to
vibrate all the instruments of corresponding pitches upon the circuit are set in
vibration, each responding to only that instrument used as a transmitter, with
which it is in unison. Thus the signals of R, Figure 16, are repeated by R of
Figures 17 and 18, but by no other instrument upon the circuit; the signals of R¹,
Figure 18, by R¹, Figures 16 and 17, and the signals of R³, Figure 17, by R³,
Figures 16 and 18, whether R, Figure 16, R¹, Figure 18, and R³, Figure 17, are
successively or simultaneously caused to vibrate. Hence by these instruments two
or more telegraphic signals or messages may be sent simultaneously over the same
circuit without interferring with one another, a single battery B being used for the
whole circuit. These instruments may be used for the simultaneous transmission of
musical notes differing in loudness as well as in pitch.
When the armature A, Figure 15, is set in vibration the armature A¹ responds
not only in pitch but in loudness. Thus, when A vibrates with little amplitude a
very soft musical note proceeds from A¹, and when A vibrates forcibly the amplitude

page_text: louder; so if R and R', Figure 16, are sounded simultaneously (R loudly and R¹
softly) the instruments. R, Figures 17 and 18, repeat loudly the signals of R,
Figure 16, and R¹², Figures 17 and 18 repeat softly those of R', Figure 16.
FOURTH PLAN.
In the plans so far described a separate instrument is employed for every pitch,
and the electrical vibrations for different pitches are combined upon the wire, each
armature being capable of transmitting or receiving but a single note, and thus as
many separate instruments are required as there are messages or musical notes to
transmit.
In this fourth part of the Invention a single instrument is employed, the armature
of which can be set in vibration by a musical instrument, or by the tones of a human
voice, or by any sound whatever.
This fourth plan is represented in Figures 21, 22, and 23, wherein is shewn a
single telephone at each station in place of the transmitting and receiving
instruments heretofore described, the telephones being illustrated separately in
Figures .19 and 20.
One of the ways in which the armature A, Figure 15, may be set in vibration
has been stated to be by wind. Another mode is shewn in Figure 19, whereby
motion can be imparted to the amature by the human voice, or by means of
musical instrument, or by sounds of any kind.
.
The armature A, Figure 19, is fastened loosely by one extremity to the uncovered
leg h of the electro-magnet E, and its other extremity is attached to the centre of a
stretched membrane n. A cone C³ is used to converge sound vibrations upon the
membrane. When a musical note is made in the neighborhood of the membrane n
it is set in vibration, the armature A is forced to partake of the motion, and thus
electrical undulations are created upon the circuit G, B. E, W, E¹, G². The
armature A¹ is thus thrown into synchronous vibration with the armature A,
emitting a musical note of similar pitch to that which originated the vibration of
armature A
If two or more musical notes be simultaneoualy sounded in the
neighborhood of the cone C the resultant Diotion of the air is copied by the
membrane n to which the armature A is attached, and this armature A acting
inductive by upon the current traversing the coils of the electro-magnet E occasions
an increase and diminution in its utensity, and the armature A¹ is thrown into
vibration by the varying attraction of the electro-magnet E to which it is attached,
and thus imparts to the air at n¹ a facsimile copy of the motion of the air that
acted upon the membrane n; hence two or more musical notes or telegraphic
messages can be sent simultaneously along a single circuit from one station to
another by means of one instrument at each station.
Instead of the cone, membrane, and armature shewn in Figure 19, a plate of thin
steel may be used, the vibrations of the plate in front of the magnet occasioned by
the motion of the air during the production of sound changes the intensity of the
current as herein-before described and occasions a similar motion in a similar steel
plate in front of another electro-magnet at another station in the circuit. Such
a. plate is shewn in Figure 20, and marked A³, it being attached to a frame F.
The telephones shewn in Figures 21 to 26 are of the kind shewn in Figure 20.
This Invention is not limited however to the use of a steel plate, but includes
within its scope any materials capable of inductive action, upon a current of
electricity. In this plan an operator at station; Figure 21, may send a telegraphic
message on a certain pitch, while another operator at another station, say, Figure 22,
is transmitting another message on a different pitch, and both sounds will be audible
at all the stations in the circuit.
The receiving operators will pay attention to signals of only one pitch, hence by
this plan the simultaneous transmission of a number of telegraphic messages over a
single circuit in the same or both directions with a single main battery for the whole

page_text: circuit and a single telephonic instrument at each station is rendered possible..
Whatever sound is made in the neighborhood of any telephone, say, T, e, Figure 21,.
is echoed in facsimile by the telephones T, e, of all the other stations, hence this.
fourth plan is also adapted for the entirely new use of transmitting intelligibly the
exact sounds of articulate speech.
To convey an articulate message it is only necessary for the operator to speak in
the neighborhood of a telephone, say T, e, Figure 21, and for the receiving operator
at another instrument, say, T, e, Figure 23, to listen.
If two persons speak simultaneously in the neighborhood of the same or different
telephones, the utterances of the two speakers are reproduced simultaneously by all
the other telephones on the same circuit, hence, by this plan vocal messages may be
transmitted simultaneously over the same circuit in the same or opposite directions,
with one battery for the whole circuit, and one telephone at each station on the line.
In this plan of transmitting vocal utterances it is only necessary that the strength
of the current should vary in intensity as the air varies in density during the
utterance of the sound.
All the methods of producing undulating currents of electricity herein-béfore:
described may be employed in producing the undulations by which to transmit
articulate messages. For instance, the vibrations of a membrane may cause a
platinum wire to vibrate in water or other liquid of high resistance included in the
circuit, and hence will occasion changes in the intensity of the current traversing
the circuit proportional to the changes in the density of the air which originally
gave rise to the vibrations of the membranes, and hence the sounds uttered in the
neighborhood of that membrane will be reproduced from a telephone on a distant
part of the circuit.
In the fifth plan of the Invention, illustrated in Figures 24, 25, and 26, the
battery is omitted, and a permanent magnet M³ is substituted for the soft iron core
of the electro-magnets used in the other telephones; or the coils shown in Figures
24, 25, and 26 may be induction coils of usual construction, local batteries. being
placed in circuit with the primary wires so as to magnetize the soft iron cores of the
coils, the unduations induce in the secondary wires by the vibration of the plates
A³-being directed upon the line wire.
The sixth plan of the Invention is represented in Figures 27, 28, and 29, Figure 27
being a side view of a receiving instrument R, having a magnet E and armature,
as before described, and provided also with a vibratory circuit breaker V; this
circuit breaker is designed for the purpose of enabling the armature A to open or
close a local circuit through the medium of the circuit breaker V; this circuit.
breaker consists of a light. metallic lever normally resting upon the point 5, pre-
ferably adjustable so as to close a local circuit. The extremity of the circuit breaker
overhangs the free end of the armature A.
When the armature A is thrown into vibration by the action of magnet E, the.
circuit breaker is lifted from the point 5, and it does not return until the cessation.
of the vibration of the armature A.
In Figure 28 an arrangement is shewn whereby the lifting of the circuit
breaker opens a local circuit, in which is placed a Morse sounder 6 or other
electrical apparatus.
In Figure 29 the circuit breaker V normally "short circuits" the battery B,
cutting off the current from the Morse sounder 6, or other apparatus, so that the
lifting of the circuit breaker V permits the current from the battery B to actuate
the telegraphic instrument 6. The vibrating circuit breaker V may be changed in
construction, it only being necessary that it have normally a slower rate of vibration
than the armature A, by. which it is vibrated:
Figure 30 represents an arrangement of transmitting instruments T, T², T, &c.,
and receiving instruments R, RI, &c., and vibratory circuit breakers V, V₁, &c.,
similar to those shewn in Figures 1, 2, 27, designed to produce automatically at
the. receiving end of the line a facsimile of whatever characters or marks are pre-
sented at the transmitting end. In this plan the messages or marks to be copied

page_text: may be written or printed in non-metallic ink on a metallic surface F, o, shown in
dotted lines (preferably tinfoil), or impressed upon the same; this metallic surface
is placed upon a suitable metallic support S, preferably made as a roller, having its
axis at 7 connected with the battery B and the earth G. At the receiving end a
similar support S₁ is connected in circuit with a battery B' and the vibratory circuit
breakers V, VI, V, &c., and on this support is placed a piece or strip of chemically
prepared paper P, a, shewn in dotted lines.
The metallic surface F, o, on which is written the message to be transmitted, is
noved between the support S and the ends of a series of wires 8, 9, 10, 11, 12, 13,
&c., such ends being held by a non-metallic holder or bar 14. The wires 8, 9, 10,
&c., communicate with the armatures a of transmitters T, T¹, &c., similar to the
transmitter T, shewn in Figure 1. At the receiving end of the circuit the ends of a
similar arrangement of wires 15, 16, 17, 18, 19, and 20 are held in place by a non-
metallic holder 21, so as to rest upon the chemically prepared paper
Pa.
The metallic surface F, o, and the chemically prepared paper P, a, are each moved
in the direction of the arrows under their respective series of wires, but not necessarily
at equal speed, and the characters or marks on the foil are copied on the prepared paper.
When the end of any of the wires at the transmitting end, say wire 8, rests upon
the metallic foil, a communication is established between the battery B and the
armature a of the transmitter T, the platinum rivet r, as heretofore described,
vibrates, and makes and breaks contact with the point m, so that an intermittent
current of electricity appears upon the line wire W; so long then as the wire 8 rests
on the metallic surface F, o, the currents of c pass through 7, S, F, o, 8, r, m, to the
line wire W, and thence by branches through the receiving instruments R, R¹, &c.,
to the earth at G¹.
The armature of the receiving instrument R, which is in unison with the arma-
ture a of the transmitter T, is thrown into vibration by the passage of the inter-
mittent current, but the armatures of the other transmitting instruments R¹, R², &c.,
having a different rate of vibration from the armature of T, do not respond.
The armature of the receiving instrument R in the course of its vibration lifts the
spring lever V, breaking the circuit B³, S¹, P, a, 15, V, B'; so long then as the end
of the wire 8 rests upon the metallic surface F, o, the local circuit in which the wire 15
is placed remains open, and thus no mark is made upon the paper P, a, under wire 15.
When during the movement of the metallic surface F, o, a portion of the non-
metallic ink comes under the end of the wire.8, the connection between the battery
B and transmitter T is broken, the receiver R becomes silent, the spring lever V
returns to its normal position, closing the circuit above described, and a mark is
made upon that part of the chemically prepared paper P, a, under wire 15.
Each wire 9, 10, &c., operates in a like manner to the wire 8, and the wires 16, 17,
18, &c., operate as described for wire 15.
Any of the ordinary chemically prepared paper used in connection with ordinary
systems of chemical or autograph telegraphs may be used.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Morgan-Brown in the Great Seal Patent Office on the 9th
June 1877.
WILLIAM MORGAN-BROWN, of the Firm of Brandon and Morgan-Brown,
Engineers and Patent Agents, of 38, Southampton Buildings, London, and 1, Rue
Lattitte, Paris. "IMPROVEMENTS IN ELECTRIC TELEPHONY (TRANSMITTING OR
CAUSING SOUNDS FOR TELEGRAPHING MESSAGES) AND TELEPHONIC APPARATUS."
A communication from abroad by Alexander Graham Bell, of the University of
Boston, Massachusetts, United States of America, Professor of Vocal Physiology.
This Invention of improvements in electric telephony (transmitting or causing
sounds for telegraphing messages) and telephonic apparatus relates to electric
telephony and telephonic apparatus,

page_text: of z pass to the ground at G, and the currents of c pass through K, 8, r, m, s¹, to the
line wire W, and thence through the electro-magnet E of the receiver R to the
ground at G. When the rivet leaves the point m the main circuit is broken.
So long then as the key K is depressed the vibration of a occasions an intermittent
action of the current from the battery B upon the line wire W, and the armature A
of the receiver R is attracted in an intermittent manner by its electro-magnet E.
When the makes and breaks of the circuit at m, r, are timed to the normal move-
ments of the armature A of the receiving instrument, that is, when A is tuned to
yield the same musical pitch as the armature a of the transmitting instrument, then
the armature A is thrown into strong vibration, thereby causing it to emit its
musical note.
When the key K is raised the communication between the main battery B and the
transmitter T is cut off, and A. becomes silent. So long as the key K is depressed
a musical note is omitted by A, and the duration of this note can be made to signify
the dot or dash of the Morse alphabet; thus a telegraphic despatch can be sent
from T to R by manipulating the key K in the usual manner.
Figures 3, 4, and 5, Sheet 2, illustrate the combination of these instruments upon
a telegraphic circuit so as to permit of the simultaneous transmission of a number
of telegraphic messages along a single wire.
The armatures of the transmitters and receivers that are numbered alike at all
the stations have the same pitch; thus the transmitter T of Figure 3 is the unison
of the transmitter T at the station represented in Figure 4, and also of the
receiver R at the stations shown in Figures 3, 4, and 5.
The sounds produced by the transmitters T, T¹, T, &c., differ in pitch from one
another, and are so arranged that each transmitter can affect one and one only of
the receiving instruments R, R¹, R', &c., at each station upon the line.
To illustrate the operation of this form of the Invention depress any key, say
key K¹, Figure 3. A communication being thereby established between the main
battery B and the transmitting instrument T¹, an intermittent current passes on to
the main line through the receiving instruments R, R1, R2, &c., of Figures 3, 4,
and 5 to the earth at G, Figure 5. The receiving instruments R², Figures 3, 4,
and 5, respond so long as the key K, Figure 3, is depressed, and become silent the
moment it is raised. The other instruments R, R³, &c., at stations Figures 3, 4,
and 5 remain silent, so that a telegraphic message transmitted by the manipulation
of key K, Figure 3, is received upon only its corresponding receiving instrument at
each station toward that station herein shown as Figure 5, where the receiving
instruments are connected directly with the earth.
The instruments shown in Figure 4 operate as just described for those of Figure 3,
the depression of each key K, K, or K, &c., operating those receiving instruments
in stations 4 and 5 that are in unison with the transmitting instrument connected
with the key, but does not affect the instruments in Figure 3 or in that direction.
To illustrate the simultaneous transmission of telegraphic messages by these
instruments an operator in the station, shown in Figure 3, is supposed to manipulate
the key K, while at at the same time another operator in station, Figure 4, is trans-
mitting an entirely different despatch by the manipulation of the key K¹. The
signals produced by the depression of key K, Figure 3, are received by the receivers R
of Figures 3, 4, and 5, and the signals due to the manipulation of the key K¹,
Figure 4, affect the receiving instrument R' of Figures 4 and 5, but not R¹ of
Figure 3, or of any station in the direction of Figure 3; hence although upon this
plan two or more messages may be sent simultaneously over the same circuit from
the same or different stations to the same or different stations, still as the signals
pass only in one direction two line wires are required to complete communication
in both directions. Intermittent currents adapted to work these instruments may
be produced without actually making and breaking the circuit, as herein-before
described, by suddenly increasing and diminishing the intensity of the current.
Such currents are termed for the sake of distinction "pulsatory." Intermittent and
pulsatory currents may be of two kinds, accordingly as the electrical impulses have
6.

page_text: "
all the same polarity or are alternately positive and negative. In the former case
they are termed "direct," in the latter reversed," currents. These distinctions are
graphically illustrated in Figures 6 and 7.
SECOND PLAN AS DEVISED BY MY COMMUNICATOR.
In order to secure communication in both directions upon a single circuit this
second plan was devised, and it is illustrated in Figures 8, 9, and 10. In these
Figures the instruments employed are similar to those shown in Figures 1, 2, 3,
4, and 5, and like instruments are denoted by like letters; but instead of con-
necting the transmitting instruments T, T¹, T, &c., directly with the receiving
instruments R, R¹, R³, &c., as in Figures 3, 4, &c., they are connected with the
primary wires of an induction coil I of usual construction, and the currents induced
in the secondary wires of the coil are directed to the receiving instruments
R, R¹, R, &c., on the line wire. By this arrangement the receiving instruments
at the terminal stations, Figures 8 and 10, are connected directly with the earth
at G, and signals made at any one station appear at all the stations on the circuit.
On this plan, therefore, two or more messages may be sent simultaneously over a
single circuit in the same or in opposite directions.
THIRD PLAN,
In the methods, heretofore described, employing intermittent currents of electricity
the limit to the number of signals that can be sent simultaneonsly over the same
wire is very speedily reached, for when a number of transmitting instruments
having different rates of vibration are simultaneously making and breaking the
same circuit, the effect upon the main line is practically equivalent to one continuous
current. In addition to this objection, local and main batteries are required at
every station on the line. Similar difficulties are experienced in employing pulsatory
currents. To obviate these difficulties the plan of using an undulatory current of
electricity, as described in this part of the Invention, was devised.
It has long been known that when a permanent magnet is caused to approach
the pole of an electro-magnet a current of electricity is induced in the coils of the
latter, and that when it is made to recede a current of opposite polarity to the first
appears upon the wire. When therefore a permanent magnet is caused to vibrate
in front of the pole of an electro-magnet an undulatory current of electricity is
induced in the coils of the electro-magnet, the undulations of which correspond in
rapidity of succession to the vibrations of the magnet, in polarity to the direction
of its motion, and in intensity to the amplitude of its vibration, or rather to the
velocity of its motion. A current of this character is graphically represented in
line 3, Figure 7, Sheet 1. When the permanent magnet is caused to vibrate in
front of the pole of an electro-magnet which is placed in circuit with a voltaic
battery, the undulatory current induced by the vibration of the permanent magnet
is superposed upon the voltaic current. When the induced impulse is of similar
polarity to the voltaic currents it serves to strengthen the intensity of the latter,
but when it is of opposite polarity it tends to neutralize the voltaic current. . Ip
such an arrangement the resultant effect of the vibration of the permanent magnet
is to throw the battery currents into waves, as in line 3, Figure 6, by alternately
increasing and diminishing the intensity of the current. Such increase and diminu-
tion in the intensity of the current does not take place with the suddenness
characteristic of a pulsatory current (see line 2, Figure 6), but is proportional to
the increase and diminution of the density of the air during the vibration of the
inducing body.
The various kinds of electrical currents denominated intermittent; pulsatory, and
undulatory are graphically represented in Figures 6 and 7. In Figure 6 the
currents are direct, that is, the electrical impulses 62, 62, 63, &c., are all of the same
polarity, either positive or negative, and in Figure 7 the currents are "reversed,”
that is, the electrical impulses are alternately positive and negative.
Direct Intermittent Current (shown in line 1, Figure 6). The impulses 6º, 6º, &c.,

page_text: are all of positive or all of negative electricity, and the vertical thickness of the
lines 62, 63, &c., measured from the zero line 21, 21, represents the intensity of the
current at the part observed. The horizontal extension of the line 6' indicates the
duration of the electrical impulse, and the horizontal extension of the space ƒ*
shows the length of time the current is absent from the circuit.
Reversed Intermittent Current (shown in line 1, Figure 7).-Impulses of positive
electricity are represented above, and impulses of negative electricity below, the
zero line 2¹, z¹, and the impulses b², d, are respectively positive and negative, or
vice versa.
Direct Pulsatory Current (shown in line 2, Figure 6).-The current of electricity
represented is continuous but it changes suddenly in intensity, the elevations
b², d, &c., indicating the impulses of maximum intensity and the depressions c², c²,
the impulses of minimum intensity. As before, the vertical thickness of the line
indicates the strength of the current.
Reversed Pulsatory Current (shown in line 2, Figure 7).-The impulses b², ²,
are alternately positive and negative without any break in the continuity of the
current.
Direct Undulatory Current (shown in line 3, Figure 6). As before, the vertical
thickness of the line represents the strength of the current, the elevations 62, 6², &c.,
express the impulses of maximum intensity and c³, c, &c., those of minimum
intensity. The changes of intensity, as illustrated in line 3, do not occur with the
suddenness characteristic of pulsatory currents, as shown in line 2, but are pro-
portional to the changes in the density of the air during the production of a sound.
Reversed Undulatory Current (shown in line 3, Figure 7).—The elevations bª, 6³,
&c., indicate impulses of positive, and the depressions d², d², impulses of negative,
electricity, the vertical thickness of the portions b³, d², indicating the intensity of
the positive or negative impulse at the part observed. The oscillations of the current
above and below the zero line correspond to the increase and diminution of the
density of the air during the production of a sound, hence the elevations b³, b², &c.,
correspond to condensations of air and the depressions d²,.ds, &c., to rarefactions,
the intensity of the positive or negative impulses being proportioned to the degree
of density or rarity of the air.
The differences between intermittent, pulsatory, and undulatory currents will be
more clearly understood by describing and illustrating the condition of the electrical
current when the attempt is made to transmit two musical notes simultaneously,
first upon one plan and then upon the others. Let the interval between the two
sounds be a major third, then their rates of vibration are in the ratio of 4 to 5.
Now when an intermittent current is used the circuit is made and broken four
times by the armature a, Figure 11, Sheet 1, of one transmitting instrument in the
same time that five makes and breaks are caused by the armature a¹ of the other
transmitting instrument; A and B, Figure 11, represent the intermittent currents
produced, four impulses of B' being made in the same time as five impulses of A*;
6,6, &c., Figure 11, show where and for how long time the circuit is made, and
ff, &c., indicate the duration of the breaks of the circuit. The line A² + B¹
shows the total effect upon the current when the armatures a, a¹, Figure 11, are
caused simultaneously to make and break the same circuit, and the combined effect.
upon the current passing through the receiver R, shown at A³ + B³, Figure 11, is
very nearly equivalent to a continuous current.
When many transmitting instruments of different rates of vibration are simul-
taneously making and breaking the same circuit the current upon the main line
becomes for all practical purposes continuous.
When the armatures a, a¹, are arranged upon circuit, as shown in Figure 12,
pulsatory currents traverse the coils of the receiving instrument R. The line As
represents the pulsatory current due to the action of one armature a, and the line B*
the action due to the other armature a²; b², b², &c., represent impulses of maximum
intensity, and c³, c³, &c., impulses of minimum intensity. Four impulses of B* aro
made in the same time as five impulses of A², and the line A + B reprosents
-

page_text: the total effect upon the current passing through the coils of the receiver R, when
the armatures a and a¹ are caused to vibrate simultaneously. This effect is nearly
equivalent to a continuous current of minimum intensity.
Next consider the effect when undulatory currents are employed. Electrical
undulations induced by the vibration of a body M, Figure 13, capable of inductive
action can be represented graphically by the same sinusoidal curve which expresses
the vibration of the inducing body itself, for, as above stated, the rate of oscillation
in the electrical current is the same as that of the inducing body. The intensity of
each induced impulse is proportional to the velocity of the motion of the inducing
body, and the polarity of each induced impulse depends upon the direction of the
motion of the inducing body to or from the pole of its electro magnet.
sinusoidal curves A and B, Figure 13, represent graphically the electrical undu-
lations induced in a circuit by the vibration of permanent magnets M and M³, or
other bodies capable of inductive action.
The
The portions 62, 63, &c., represent impulses of positive electricity, and d², d², &c.,
impulses of negative electricity. The horizontal line 2¹, ¹, represents the zero of
current, and the vertical distance of any portion of the curve 6 or from the
zero line expresses the intensity of the positive or negative impulse at the part
observed.
The vibrations represented by the sinusoidal curves B and A², Figure 13, are in
the ratio aforesaid of four to five, that is, four oscillations of B' are made in the
same time as five oscillations of A². The combined effect of A² and B when
induced simultaneously on the same circuit is expressed by the curve A³ + B³,
Figure 13, which is the algebraical sum of the sinusoidal curves A² and B². In
Figure 14 the permanent magnets M and M' are caused to vibrate in front of the
poles of electro-magnets e, e', placed in circuit with a battery B; by such an
arrangement the battery current is thrown into waves. The lines A² and B
represent the undulatory currents produced respectively by the vibrations of M
and M², and as in the other instances four impulses of B are made in the same
time as five impulses of A²; the elevations b², b, &c., indicate impulses of maximum
intensity, and the depressions ca, c², &c., impulses of mininum intensity; the vertical
distance of any portion of the curve b, c, from the zero line 21, 2¹, expresses
the intensity of the current at part observed; the line A² + B* expresses the
resultant effect upon the current when the permanent magnets M, M³, are caused
simultaneously to vibrate; the curves A² + B2, Figures 13 and 14, also indicate the
actual motion of the air when the two magnets M, M², are vibrated simultaneously.
Thus when electrical undulations of different rates are simultaneously produced
upon the same circuit the effect is exactly analogous to that occasioned in the air by
the vibration of the inducing bodies. Hence the co-existence upon a telegraphic
circuit of electrical undulations corresponding to sounds of different pitch is
manifested not by the obliteration of the vibratory character of the current, as with
intermittent and pulsatory currents, but by peculiarities in the shapes of the
electrical undulations, or in other words by peculiarities in the shapes of the curves
which represent those undulations..
A
There are many ways of producing undulatory currents of electricity dependent
for effect upon the vibration or motion of bodies capable of inductive action.
few of the methods that may be employed are as follows:-When a wire through
which a continuous current of electricity is passing is caused to vibrate in the
neighbourhood of another wire an undulatory current of electricity is induced in
the latter. When a cylinder upon which are arranged bar magnets is made to
rotate in front of the pole of an electro-magnet an undulatory current of electricity
is induced in the coils of the electro-magnet.
Undulations are caused in a voltaic current by the vibration or motion of bodies
capable of inductive action, or by the vibration of the conducting wire itself in the
neighbourhood of such bodies. Electrical undulations may also be caused by
alternately increasing and diminishing the resistance of the circuit, or by alternately
increasing and diminishing the power of the battery. The internal resistance of a

page_text: :
:
.
battery is diminished by bringing the voltaic elements nearer together and increased
by placing them farther apart; the reciprocal vibration of the elements of a battery
therefore occasions an undulatory action in the voltaic current.
The external resistance may also be varied; for instance, let water or some other
liquid of high resistance form part of a voltaic circuit, then the more deeply the
conducting wire is immersed in the water or other liquid the less resistance does the
liquid offer to the passage of the current; hence the vibration of the conducting
wire in water or other liquid included in the circuit occasions undulations in the
current. The vertical vibration of the elements of a battery in the liquid in which
they are immersed produces an undulatory action in the current by alternately
increasing and diminishing the power of the battery.
In illustration of one method of creating electrical undulations a form of apparatus
is shown in Figure 15. It is preferable to employ for this purpose an electro-
magnet E, Figure 15, having a coil upon only one of its legs. A steel spring
armature A is firmly clamped by one extremity .to the uncovered leg of the
magnet, and its free end is allowed to project above the pole of the covered leg.
The armature A can be set in vibration in a-variety of ways, one of which is by
wind, and in vibrating it produces a musical note of a certain definite pitch.
When the electro-magnet E is placed in a voltaic circuit B, E, W, E¹, B, the
'armature A becomes magnetic, and the polarity of its free end is opposed to that of
the magnet underneath. So long as the armature. A remains at rest no effect is
produced upon the voltaic current, but the moment it is set in vibration-to produce
its musical note a powerful inductive action takes place and electrical undulations
traverse the circuit above described. The, undulatory current passing through the
coil of the electro-magnet' E' causes vibration in its armature A¹ when the armatures"
of the two magnets are normally in unison with one another, but the armature A¹
is unaffected by the passage of the undulatory current when the pitches of the two
armatures are different.
The instruments shown in Figure 15 are like in plan to the receiving instru-
ments R, R¹, &c., of Figures 1, 2, 3, 4, 5, 8, 9, 10: A number of instruments may
be placed upon a telegraphic circuit, as in Figures 16, 17, 18.. When the armature
of any one of the instruments is set in vibration all the other instruments upon the
circuit which are in unison with it respond, but those which have normally a
different rate of vibration remain silent. Thus if R, Figure 16, is set in vibration
the armatures of the receivers R, Figure 17, 18; vibrate also, but all the others on:
⚫ the circuit remain still. So if R¹, Figure 17, is caused to emit its musical note the
instruments R', shown in Figures 16 and 18, respond. They continue sounding so
long as the mechanical vibration of R¹, Figure 17, is continued, but become silent
with the cessation of its motion. The duration of the sound may be used to
- indicate the dot or dash of the Morse alphabet, and thus a telegraphic dispatch may
be indicated by alternately interrupting and renewing the sound.
When two or more instruments of different pitch are simultaneously caused to
vibrate, all the instruments of corresponding pitches..upon the circuit are set in
vibration, each responding to only that instrument used as a transmitter with which
it is in unison. Thus the signals of R, Figure 16, are repeated by R of Figures 17:
and 18, but by no other instrument upon the circuit. The signals of R¹, Figure 18,
by R¹, Figures 16 and 17, and the signals of R, Figure 17, by R³, Figures 16 and 18,
whether R, Figure 16, R', Figure 18, and R, Figure 17, are successively or simul-
taneously caused to vibrate. Hence by these instruments'two or more telegraphic
signals or messages may be sent simultaneously over, the same circuit without
interfering with one another, a single battery B being used for the whole circuit.
These instruments may be used for the simultaneous transmission.of musical notės
differing in loudness as well as in pitch.
When the armature A, Figure 15, is set in vibration the armature A¹ responds not
only in pitch but in loudness. Thus when A vibrates with little amplitude a very
soft musical note proceeds from A¹, and when A vibrates forcibly the amplitude of
the vibration of A' is considerably increased,, and the resulting sound becomes

page_text: Sgs Of IV,
Figure 16, and R¹, Figures 17 and 18 repeat softly those of R¹, Figure 16.
FOURTH PLAN.
In the plans so far described a separate instrument is employed for every pitch,
and the electrical vibrations for different pitches are combined upon the wire, each
armature being capable of transmitting or receiving but a single note, and thus as
many separate instruments are required as there are messages or musical notes to
transmit.
In this fourth part of the Invention a single instrument is employed, the armature
of which can be set in vibration by a musical instrument or by the tones of the
human voice, or by any sound whatever.
This fourth plan is represented in Figures 21, 22, and 28, wherein is shown a
single telephone at each station in place of the transmitting.
ments heretofore described, the telephones being illustrated separately in Figures 19
and receiving instru-
and 20.
One of the ways in which the armature A, Figure 15, may be set in vibration has
been stated to be by wind. Another mode is shown in Figure 19, whereby motion
can be imparted to the armature by the human voice, or by means of a musical
instrument, or by sounds of any kind
The armature A, Figure 19, is fastened loosely by one extremity to the uncovered
leg h of the electro-magnet E, and its other extremity is attached to the centre of
a stretched membrane n. A cone C is used to converge sound vibrations upon the
membrane. When a musical note is made in the neighbourhood of the membrane n
it is set in vibration, the armature A is forced to partake of the motion, and thus
electrical undulations are created upon the circuit G, B, E, W, E¹, G¹. The
armature A is thus thrown into synchronous vibration with the armature A,
emitting a musical note of similar pitch to that which originated the vibration of.
armature A. If two or more musical notes be simultaneously sounded in the
neighbourhood of the cone C, the resultant motion of the air is copied by the
membrane n to which the armature A is attached; and this armature A, acting
inductively upon the current traversing the coils of the electro-magnet E, occasions
an increase and diminution in its intensity, and the armature A is, thrown into
vibration by the varying attraction of the electro-magnet E¹ to which it is attached,
and thus imparts to the air at n¹ a facsimile copy of the motion of the air that
acted upon the membrane n, hence two or more musical notes or telegraphic.
messages can be sent simultaneously along a single circuit from one station to.
Another by means of one instrument at each station.
Instead of the cone membrane and armature shown in Figure 19 a plate of thin
steel may be used; the vibrations of the plate in front of the magnet occasioned by
the motion of the air during the production of sound changes the intensity of the
current as herein-before described, and occasions a similar motion in a similar steel
plate in front of another electro-magnet at another station in the circuit. Such a
plate is shown in Figure 20 and marked A³, it being attached to a frame F. The
telephones shown in Figures 21 to 26 are of the kind shown in Figure 20. This
Invention is not limited however to the use of a steel plate, but includes within
its scope any material capable of inductive action upon a current of electricity. In
this plan an operator at station Figure 21 may send a telegraphic message on a
certain pitch, while another operator at another station, say, Figure 22, is transmitting
another message on a different pitch, and both sounds will be audible at all the
stations in the circuit.
The receiving operators will pay attention to signals of only one pitch, hence by
this plan the simultaneous transmission of a number of telegraphic messages over
a single circuit in the same or both directions with a single main battery for the
whole circuit, and a single telephonic instrument at each station, is rendered possible.

page_text: Whatever sound is made in the neighbourhood of any telephone, say, T, e, Figure 21,
is echoed in facsimile by the telephones T, e, of all the other stations, hence this
fourth plan is also adapted for the entirely new use of transmitting intelligibly the
exact sounds of articulate speech.
To convey an articulate message it its only necessary for the operator to speak in
the neighbourhood of a telephone, say T, e, Figure 21, and for the receiving operator
at another instrument, say T, e, Figure 23, to listen.
If two persons speak simultaneously in the neighbourhood of the same or different
telephones, the utterances of the two speakers are reproduced simultaneously by all
the other telephones on the same circuit; hence by this plan, vocal messages may
be transmitted simultaneously over the same circuit in the same or opposite
directions with one battery for the whole circuit and one telephone at each station
on the line. In this plan of transmitting vocal utterance it is only necessary that
the strength of the current should vary in intensity as the air varies in density
during the utterance of the sound.
All the methods of producing undulatory currents of electricity herein-before
described may be employed in producing the undulations by which to transmit
articulate messages. For instance the vibrations of a membrane may cause a
platinum wire to vibrate in water or other liquid of high resistance included in the
circuit, and hence will occasion changes in the intensity of the current traversing
the circuit proportional to the changes in the density of the air, which originally
gave rise to the vibrations of the membrane, and hence the sounds uttered in the
neighbourhood of that membrane will be reproduced from a telephone on a distant
part of the circuit.
In the fifth plan of the Invention, illustrated in Figures 24, 25, and 26, the
battery is omitted and a permanent magnet M³ is substituted for the soft iron core
of the electro-magnets used in the other telephones. Or the coils shown in.
Figures 24, 25, and 26, may be induction coils of usual construction, local batteries
being placed in circuit with the primary wires so as to magnetize the soft iron cores
of the coils. The undulations induced in the secondary wires by the vibration of
the plates A being directed upon the line wire.
"
The sixth plan of the Invention is represented in Figures 27, 28, and 29,
Figure 27-being a side view of a receiving instrument R having a magnet E and
armature A as before described, and provided also with a vibratory circuit
breaker V. This circuit breaker is designed for the purpose of enabling the
armature A to open or close a local circuit through the medium of the circuit
breaker V. This circuit breaker consists of a light metallic lever normally resting
upon the point 5, preferably adjustable, so as to close a local circuit. The extremity
of the circuit breaker overhangs the free end of the armature A. When the
armature A is thrown into vibration by the action of magnet E, the circuit breaker
is lifted from the point 5, and it does not return until the cessation of the vibration
of the armature A.
In Figure 28 an arrangement is shown whereby the lifting of the circuit
breaker V.opens a local circuit in which is placed a Morse sounder 6 or other
electrical apparatus.
In Figure 29 the circuit breaker V. normally "short circuits" the battery B,
cutting off the current from the Morse sounder 6 or other apparatus, so that the
lifting of the circuit breaker V permits the current from the battery B to actuate
telegraphic instrument 6. The vibrating circuit breaker V may be changed in con-
struction, it only being necessary that it have normally a slower rate of vibration
than the armature A by which it is vibrated.
4
Figure 30 represents an arrangement of transmitting instruments T; T¹; Tº, &c.,
and receiving instruments R, R¹, &c., and vibratory circuit breakers V, V₁, &c.,
similar to those shown in Figures 1, 2, 27, designed to produce automatically at the
receiving end of the line a facsimile of whatever characters or marks are presented 5
at the transmitting end. In this plan the messages or marks to be copied may be
written or printed in non-metallic ink on a metallic surface F, o, shown in dottod

page_text: lines (preferably tin foil) or impressed upon the same. This metallic surface is
placed upon a suitable metallic support S preferably made as a roller, having its
axis at 7 connected with the battery B and the earth G. At the receiving end a
similar support S¹ is connected in circuit with a battery B' and the vibratory
circuit breakers V, V, V, &c., and on this support is placed a piece or strip of
chemically prepared paper P, a, shown in dotted lines.
The metallic surface F, o, on which is written the message to be transmitted, is
moved between the support S and the ends of a series of wires 8, 9, 10, 11, 12,
13, &c., such ends being held by a non-metallic holder or bar 14. The wires 8, 9;
10, &c., communicate with the armatures a of transmitters T, T¹, &c, similar to the
transmitter T shown in Figure 1.
At the receiving end of the circuit the ends of a similar arrangement of wires 15,
16, 17, 18, 19, and 20, are held in place-by a non-metallic holder 21, so as to rest
upon the chemically prepared paper P, a.
The metallic surface F, o, and the chemically prepared paper P, a, are each moved
in the direction of the arrows under their respective series of wires, but not
necessarily at equal speed, and the characters or marks on the foil are copied on the
prepared paper.
When the end of any of the wires at the transmitting end, say wire 8, rests upon
the metallic foil a communication is established between the battery B and the
armature a of the transmitter T; the platinum rivet r, as heretofore described,
vibrates and makes and breaks contact with the point m, so that an inter-
mittent current of electricity appears upon the line wire W. So long then as the
wire 8 rests on the metallic surface F, o, the currents of o pass through 7, S, F, o, 8,
r, m, to the line wire W, and thence by branches through the receiving instru-
ments R, R¹, &c., to the earth at G¹.
The armature of the receiving instrument R, which is in unison with the
armature a of the transmitter T, is thrown into vibration by the passage of the
intermittent current, but the armatures of the other transmitting instru-
ments R¹, R³, &c., having a different rate of vibration from the armature of T do
not respond.
The armature of the receiving instrument R in the course of its vibration lifts the
spring lever V, breaking the circuit.B³, S³, P, a, 15, V, B¹. So long then as the end
of the wire 8 rests upon the metallic surface F, o, the local circuit in which the -
wire 15 is placed remains open, and thus no mark is made upon the paper P, a,
under wire 15.
When during the movement of the metallic surface F, o, a portion of the non-
metallic ink comes under the end of the wire 8, the connection between the
battery B and transmitter T. is broken, the receiver R becomes silent, the spring
lever V returns to its normal position, closing the circuit above described, and a
mark is made upon that part of the chemically prepared paper P, a, under wire 15.
Each wire 9, 10, &c., operates in a like manner to the wire 8, and the wires 16,
17, 18, &c., operate as described for wire 15.
.
Any of the ordinary chemically prepared paper used in connection with ordinary
systems of chemical or autograph telegraphs may be used.
Referring again to the fifth plan, the magnet may be of the horse-shoe form as
shown at 24 in Figure 31; and the coils of insulated wire 25 may surround soft
iron cores or pole pieces 26, screwed or otherwise fastened to the ends of the
magnet 24. The cores or pole pieces are placed near the face of the metallic
plate A³, it being attached to a cup-shaped block 28, having a central orifice 29 for
the reception of a speaking or hearing tube to convey sounds to or from the
plate A The magnet is attached to a stud 30 adapted to be moved in suitable
grooves in the base 31 by means of a screw 32 having its end connected with the
stand, the body of the screw being fitted to turn in a screw threaded stud. The
movements of the screw are just the distance between the pole of the magnet and
the plate A³, and permit the poles to be placed almost in contact with the plate.

page_text: The coils may be placed about the ends of the magnet 24, and the soft iron pole
pieces be omitted.
Figure 32 represents in perspective a telephone of the kind shown in Figure 31
when placed within a sounding box 33. The coils will preferably be very thin,
and be placed at the extremity or extremities of the magnet. One, two, or more
magnetic poles with coils may be placed near a plate to intensify the effect.
The soft iron core and coil may be attached to the plate instead of the magnet, or
the core may be placed upon the plate, and the coil on the magnet, or vice versa.
The magnet may be made to vibrate instead of the plate.
Having now described and particularly set forth the nature of the said Invention,
and the manner of carrying the same into effect, I would have it understood that
what I claim is,-
First. The method herein described of producing or transmitting musical notes
by means of undulatory currents of electricity, whereby two or more telegraphic
signals or messages can be transmitted simultaneously over a single circuit in the
same or opposite directions.
Second. In a system of multiple telegraphy wherein undulatory currents of
electricity are employed, the employment of receiving instruments, the armatures of
which are tuned to definite pitches so as to vibrate only when a sound of like pitch
is transmitted, substantially as described.
Third. A system of telegraphy in which the receiver is set in vibration by the
employment of undulatory currents of electricity, substantially as set forth.
Fourth. The combination, substantially as set forth, of a permanent magnet or
other body capable of inductive action with a closed circuit, so that the vibration of
the one shall occasion electrical undulations in the other or in itself, and this I claim
whether the permanent magnet be set in vibration in the neighbourhood of the
conducting wire forming the circuit, or whether the conducting wire be set in
vibration in the neighbourhood of the permanent magnet, or whether the conducting
wire and the permanent magnet, both simultaneously, be set in vibration in each
other's neighbourhood.
Fifth. The method of producing undulations in a continuous voltaic current by
the vibration or motion of bodies capable of inductive action, or by the vibration or
motion of the conducting wire itself in. the neighbourhood of such bodies, as set
forth.
"
Sixth. The method of producing undulations in a continuous voltaic circuit by
gradually increasing and diminishing the resistance of the circuit, or by gradually
increasing and diminishing the power of the battery, as set forth.
Seventh. The method of transmitting vocal or other sounds electrically by causing
the intensity of an electrical current to vary in a manner proportional to the variations
of density produced in the air by the said, sounds.
Eighth. The method of transmitting, vocal or other sounds electrically by causing
the intensity and polarity of an electrical current to vary in a manner proportional
to the velocity and the direction of motion of the particles of air during the produc-
tion of the sounds.
"
Ninth. The union upon and by means of an electric circuit of two or more
telephones constructed for operation substantially as described, so that if the plate
armatures of any one of the said instruments be moved in any manner the armatures
of all the other telephones upon the same circuit will be moved in like manner, and
if the transmitter armature be moved or vibrated by sound like sounds will be
produced by the motion or vibration of the armature of the other telephones upon
the circuit.
Tenth. In a system of electric telegraph or telephony, consisting of transmitting
and receiving instruments united uponan. electric circuit I claim the production in
the armature of each receiving, instrument of any given inotion by. subjecting, said
armature to an attraction varying in intensity, however, such variation may be
produced in the magnet, and hence I claim the production of any given sound or
sounds from the armature of the receiving instrument by subjecting said armatureto
->>

page_text: an attraction varying in intensity in such manner as to throw the armature into
that form of vibration which characterizes the given sound or sounds.
Eleventh. The combination with an electro-magnet of a plate of iron or steel or
other material capable of inductive action which can be thrown into vibration by
the movement of surrounding air, or by the attraction of a magnet.
Twelfth. In combination with a plate and electro-magnet, as before claimed, the
means herein described or their mechanical equivalents of adjusting the relative
position of the two, so that without touching they may be set as closely together as
possible.
Thirteenth. In an electric telephone the combination with the plate of a magnet
having coils upon the end or ends of the magnet nearest the plate, substantially as
described.
Fourteenth. The combination with an electric telephone, such as described, of a
sounding box, substantially as herein shown and set forth.
Fifteenth. In combination with an electric telephone, as herein described, the
employment of a speaking or hearing tube for conveying sounds to or from the
telephone, substantially as set forth.
Sixteenth. In an electric telephone the combination with a permanent magnet
and plate armature of a soft iron pole piece forming the core for the coil, substantially
as described.
Seventeenth. In a system of telegraphy in which the vibrating receiver operates
the circuit breaker of a local circuit independent of said receiver, as described, a
vibratory circuit breaker for said local circuit, consisting of a light spring arm,
whose free end overlaps the reed or vibrating portion of the receiver in combination
with a portion of the receiver in combination with a contact tip or point in said
circuit with which the spring arm makes and breaks contact, substantially as set
forth.
Eighteenth. The autograph telegraph comprising the combination of a series of
transmitters and transmitting bristles or wires, a single main wire receivers cor-
responding in number to the transmitters, tuned to a pitch to vibrate in unison
with the succession of electric impulses transmitted from their respective trans-
mitters, vibratory circuit breakers, one for each receiver, and a local circuit and
receiving bristle for each vibratory circuit breaker, the series of bristles resting
upon prepared paper, the whole for operation substantially as shown and described.
In witness whereof, I, the said William Morgan-Brown, have hereunto set my
hand and seal, this Sixth day of June, in the year of our Lord One thousand
eight hundred and seventy-seven.

page_text: DISCLAIMER AND MEMORANDUM OF ALTERATION as proposed to be
entered by the said William Morgan-Brown, of certain parts in the Specifi-
cation of the said Letters Patent, pursuant to the Statute in that case made
and provided..
WHEREAS Her Most Excellent Majesty Queen Victoria, by Her Letters Patent
under the Great Seal of the United Kingdom of Great Britain and Ireland, bearing
date the 9th day of December 1876, No. 4765, did for herself, her heir, and
successors, give and grant unto the said William Morgan-Brown, his execittora,
administrators, and assigns the sole privilege of making, using, exercising, and.
vending within the United Kingdom of Great Britain and Ireland, the Channel.
Islands, and the Isle of Man, the said Invention for the term of 14 years from the
date of the said Letters Patent: And whereas since the filing of the Specification
in pursuance of the said Letters Patent, I, the said William Morgan-Brown, uave
ascertained that some of the claims made therein are too wide, and comprise, as
forming parts of the said Invention, parts that were not new in the United Kingdom
at the date of the said Letters Patent, by reason of descriptions thereof having
been published in England before the 9th December 1870, and in particular certain
descriptions of telephonic apparatus that had been invented and used by the said
Alexander Graham Bell, in America, prior to the said date; And whereas it
has been ascertained that parts of the said Invention as described in the.said.

page_text: Specification are not of sufficient practical utility: And whereas I am desirous,
the above reasons, of amending my said Specification by Disclaimer and Memorandun
Alteration, as hereinafter set forth, and of confining the claims in the eld
Specification to arrangements of telephonic apparatus, wherein are employed
plate armatures or armatures other than those carried by a membrane, and antinge
:ments wherein are employed permanent magnets or magnets excited by batteries
which are not in the main circuit or line wire: And whereas I, the said Williara
Mergan-Brown, for the reasons aforesaid, am desirous, by and with the leave of
Her Majesty's Attorney General, to disclaim the portions of the said Specification
hereinafter mentioned, and to alter and amend the said Specification in manner
following, that is, by a Disclaimer and Memorandum of Alteration, which cannot
and does not extend the exclusive right granted by the said Letters Patent:—
13.
"
For the reasons aforesaid I insert after the word "apparatus" on page 11, line
12, of the Queen's Printers' copy of the said Specification (second edition) the words
following, "as hereinafter described and claimed in the claiming clauses hereunto
annexed;" and I strike out the whole of the paragraph on the same page 11,
beginning with the words " In all," in line 12, and ending with the word "direction"
in line 21; and on the same page 11 I strike out all the words from the word
"whereby" in line 24 down to and including the words "confusion and" in line
26; and on the same page 11 I strike out the whole of the paragraph beginning
with the words "the Invention" in line 28, and ending with word "directions"
in line 31; and I insert after the word "transmission" in line 32 of the same
page 11 the words "in the manner hereinafter described and claimed;" and on
the same page 11. I strike out all the words from the words "and two" in lines
34 and to the word "directions" in line 86 inclusive; and: I insert after the
word "transmission" in line 37 of the same page 11. the words "in the manner
hereinafter described and claimed;" and after the word "battery "in line 33 of
the same page 11 I insert the words "being used in the main circuit, or used
"otherwise than in the manner hereinafter described and claimed;" and on the
same page 11 I strike out all the words from the words "and two" in line 40° to
the word "line" in line 47 inclusive; and after the words "First Plan" in line +$
of the same page 11 I insert the words " to which no claim is made otherwise than
"in the claiming clauses hereunto annexed; and in line 19 of page 13 I strike out
-the words "as devised by my communicator," and in lieu. thereof I insert the words
following, "to which no claim is mado otherwise than in the claiming clauses
hereunto annexed;" and after the words "Third Plan" in line 33 of the saine
page 13 I insert the words "to which no clain is made otherwise than in the
claiming clauses hereunto annexed;" and after the words "Fourth Plan" in
line 19 of page 17 I insert the following words:" which is not claimed further
"than is indicated by the claims made in the claiming clauses hereunto annesed,
"and it is to be noted that no claim is made to the use of telephonic apparatus
wherein a membrane like gold beaters skin is used in combination with an
electro-magnet excited by a battery which is arranged in the main circuit or line
wire, inasmuch that such a membrane was mentioned in descriptions published in
England prior to December 9th 1876, and as such a membrane is of small utility
owing to its uncertainty of action, caused by changes due to wear, or moisture, or
atmospheric influences;" and in line 25 of the said page 17 I strike out the
word "fourth;" and in line 55 of the same page 17 I strike out the words
"may be used," and insert in place thereof the words "such as is shewn at A³ in
Figure 31 of the Drawings hereunto annexed may with greatly increased advantage
" be used as an. armature;" and in line 7 of page 18 I strike out the word
"material" and insert in place thereof the words "equivalent plate;" and I
strike out of the said page 18 the paragraph beginning with the words
"If two," in line 23, and ending with the word "sound" in line 30, and
I insert after the word and figure "and 26" in line 40 of the same page 18 the
words "which is not claimed further than is indicated by the claims made in the
“Yelaiming clatises hereunto annexed:" and after the word "Invention” in line 47
"
#

page_text: M
"
"
"
of the same page 18 I insert the words “to which no claim is made otherwise than
" in the claiming clauses hereunto annexed;" and I strike out the claiming clauses
First," "Second," and "Third од page 20, beginning with the word "first" in.
line 28 of the same page 20, and ending with the words "set forth
in line 37;
and I strike out the word "Fourth" in line 38 of the same page 20, and insert in
place thereof the word "Firat ;" and after the words "set forth" in the same line
38 I insert the words "and described respectively in the fourth and fifth plans above
" referred to, but subject always to the disclaiming notes;" and after the word
"magnet" in the same line 38' I insert a parenthesis, and after the word "action
in line 39 I insert another parenthesis, so that the words in lines 38 and 39 of page
20" or other body capable of inductive action" shall be within parentheses; and I
strike out the claiming clauses "Fifth" and "Sixth" on the said page 20, beginning
with the word 'Fifth" in line 46 of the same page, and ending with the words
"Bet. forth" in line 52; and I strike out the word "seventh" in line 53 of the
same page 20, and insert in place thereof the word "second;" and after the word
"current" in line 53 of the same page I insert the words "generated as described in
"the fourth and fifth plans, but subject always to the disclaiming notes;" and in
line 56 of the same page 20 I strike out the word "eighth," and insert in place
thereof the word "third;" and after the word "current" in line 57 of the same
page 201 insert the words "generated as described in the fourth and fifth pinos,
* but subject always to the disclaiming notes;" and I strike out the word "ninth
in line 8 of page 21, and insert in place thereof the word "fourth;" and after the
word "telephones" in line 3 of the same page 21 I insert the word "when;" and
after the word "described" in the said line 3 of the same page 21 I insert the words
"in the fourth and fifth plans, but subject always to the disclaiming notes;" and I
strike out the word "tenth" in line 10 of the same page 21, and insert in place
thereof the word "fifth;" and after the word "instruments" in line 11 of the sate
page 21 I insert the words "such as are described in the fourth and fifth plans, but
subject always to the disclaiming notes ;" and in line 15 of the same page I strike
out the word "instrument," and insert in place thereof the words "instruments such
as are above mentioned ;" and I strike.out the word "eleventh" in line 18 of the
same page 21, and insert in place thereof the word "sixth ;" and in the same line
I strike out after the word "combination" the words " with an electro magnet of,"
and insert in place thereof the words "in the manner described in the fourth and
"fifth plans, but subject always to the disclaiming notes, of an electro magnet with;"
and I strike out the claiming clause beginning with the word "twelfthı" in line 21
of the same page 21, and ending with the word "possible" in line 24 of the same
page 21; and I strike out the word "thirteenth" in line 25 of the same page, and
insert in place thereof the word "seventh;" and after the word " described" in
line 27 I insert the words "in the fourth and fifth plans, but subject always to the
disclaiming notes:" and I strike out the fourteenth and fifteenth claiming clauses
on the same page 21, beginning with the word "Fourteenth" in line 28 of the same
page 21, and ending with the words "set forth" in line 32 of the same page 21;
and in line 83 of the same page I strike out the word "sixteenth," und insert in
place thereof the word "eighth;" and after the word "described" in line 35 of the
same page I insert the words "in the fourth and fifth plans, but subject always to
"the disclaiming notes;" and I strike out the claiming clauses "seventeenth" and
"eighteenth" on the said page 21, beginning with the word seventeenth" in
line 36 of the same page, and ending with the word "described" in line 48.
And the said Specification when no disclaimed, altered, and amended (omitting
formal parts, and as printed by the Queen's Printers) will read as follows:—
“SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Morgan-Brown in the Great Seal Patent Office on the
9th June 1877.
"WILLIAM MORGAN-BROWN, of the Firm of Brandon and Morgan-Brown,
Engineers and Patent Agents, of 38, Southampton Buildings, London, and 1, Rue

page_text: 著我
#
Laffitte, Paris. • IMPROVEMENTS IN ELECTRIC TELEPHONY (TRANSMITTING OB
CAUSING SOUNDS FOR TELEGRAPHING MESSAGES) AND TELEPHONIC APPARATUS."
A communication from abroad by Alexander Graham Bell, of the University of
"Boston, Massachusetts, United States of America, Professor of Vocal Pliysiology.
"
"This Invention of improvements in electric telephony (transmitting or causing
" sounds for telegraphing messages) and telephonic apparatus relates to electric
telephony, as herein-after described, and claimed in the claitoing clauses hereunto
" annexed.
If
4:
and telephone apparatus
.
This present Invention relates to the reproduction by the necessary receiving
" instruments of any particular sounds or combinations of sounds through the
agency of an electric current, whereby articulate speech may be electrically
:transmitted.
The Invention also relates to the electrical production or transmission, in the
manner hereinafter described and claimed, of sounds of every kind by means of
undulatory currents of electricity, whereby not only musical sounds but articulate
" speech can be transmitted over a telograph line.
"
The Invention also relates to the electrical production or transmission, in the
manner hereinafter described and claimed, of sounds of every kind without &
" battery being used in the main circuit, or used otherwise than in the manner
described and claimed by means of undulatory currents of electricity, whereby
"not only musical notes but articulate speech can be transmitted over å telegraph
* line.
bestrafter
* First plan, to which no claim is made" otherwise than in the claiming clauses
"hereunto annexed.
3+
The first method of and apparates for transmitting two or more telegraphic
messages or signals simultaneously along a single wire by the employment of
transmitting instruments, each of which occasions a succession of electrical
impulses differing in rate from the others, and of receiving instruments, each
tuned to a pitch at which it will be put in vibration to produce its fundamental
note by one only of the transmitting instruments, as devised by muy communi-
"cator, is illustrated in Figures 1 and 2 of Sheet 1, and in Figures 3, 4, and 5 of
"Sheet 2
"
"The transmitting instrument T (Figure 1) consists of an electro magnet
having a steel spring armature a which is kept in continuous vibration by the
" action of a local battery b. The armature a in the course of its vibration brings
the platinum rivet r alternately into contact with two platinum points & and m,
one, , being placed in a local circuit 6, ³, l, r, a, b, and the other, m, communi-
cating with the line wire W through the scrow cap a'.
"
16
"
"The receiving instrument R, shown in plun in Figure 1, and in elevation in
Figure 2, consists of an electro magnet E having a coil upon only one of its legs.
"A steel spring armature A is firmly clamped by one extremity to the uncovered
leg of the electro magnet E, and its free end is allowed to project above the pole
"of the covered leg. Upon depressing the key K (Figure 1), a communication is
* established between the main battery B and the vibrating armature a of the
"transmitter T. When the rivet r touches the point m, the main circuit is com-
pleted. The currents of a pass to the ground at G, and the currents of e pasa
through K, 4, r, ni, a', to the line wire W and thence through the electro magnet E
"of the receiver R to the ground at G'. When the rivet r leaves the point in, the
"main circuit is broken. So long then as the key K is depressed, the vibration of
a occasions an intermittent action of the current from the battery B upon the
"line wire W, and the armature A of the receiver R is attracted in an intermittent
* manner by its electro-magnet E
"
st
.
44
When the makes and breaks of the circuit at m, r, are timed to the normal
movements of the armature A of the receiving instrument, that is, when A is
tuned to yield the same musical pitch as the armature a of the transmitting.
"

page_text: .
"
instrument, then the armature A is thrown into strong vibration, thereby causing
* it to emit its musical note.
"
is
"When the key K is raised, the communication between the main battery B
" and the transmitter T is cut off, and A becomes silent. So long as the key
depressed, a musical note is emittod by A, and the duration of this note can be
"made to signify the dot or dash of the Morse alphabat; thus a telegraphic despatch
" can be sent from T to R by manipulating the key K in the usual manner.
Figures 3, 4, and 5, Sheet 2, illustrate the combination of these instruments
upon a telegraphic circuit so as to permit the simultaneous transmission of a
"number of telegraphic messages along a single wire.
"
"The armatures of the transmitters and receivers that are numbered alike at all
*the stations have the same pitch; thus the transmitter T of Figure 3 is the
" unison of the transmitter T at the station represented in Figure 4, and also of
"the receiver R' at the stations shown in Figures 3, 4, and 5.
"
##
4
"
"The sounds produced by the transmitters T, T₁, T, &c., differ in pitch from
one another, and are so arranged that each transmitter can affect one, and one
only, of the receiving instruments R, R1, R2, &c., at each station upon the line.
料
"To illustrate the operation of this form of the Invention, depress any key, say,
key K, Figure 3, a communication being thereby established between the main
battery B and the transmitting instrument T', an intermittent current passes on
"to the main line through the receiving instruments R, R³, R', &c., of Figures 3, +,
" and 5, to the earth at G, Figure 5. The receiving instruments R¹, Figures 3, +,
and 5, respond so long as the key K', Figure 3, is depressed, and become silent
"the moment it is raised. The other instruments R, R., &c., at stations, Figures 3,
"4, and 5, remain silent, so that a telegraphic message transmitted by the
manipulation of key K', Figure 3, is received upon only its corresponding receiving
"instrument at each station toward that station, herein shown as Figure 5, where
* the receiving instruments are connected directly with the earth.
"The instruments shown in Figure 4 operate as just described for those of
Figure 3, the depression of each key, K, K₁, or K³, &c., operating those receiving
" instruments in stations and 5, that are in unison with the transmitting instru-
"ment connected with the key, but does not affect the instruments in Figure 3, or
in that direction.
"
44
M
:
to the same or different stations,
To illustrate the simultaneous transmission of telegraphic messages by these
" instruments, an operator in the station, shown in Figure 3, is supposed to manipu-
"late the key K, while at the same time another operator in. station, Figure +, is
transmitting an entirely different despatch by the manipulation of the key K'. The
signals produced by the depression of key K. Figure 3, are received by tho
"receivers R of Figures 3, 4, and 5, and the signals due to the manipulation of the
key K, Figure 4, affect the receiving instrument R' of Figures 4 and 5, but not
R' of Figure 3, or of any station in the direction of Figure 3, hence although
upon this plan two or more messages may bo sent simultaneously over the same
circuit from the same or different stations, still as the siguals pass only in one
"direction two line wires are required to complete communication in both
"directions. Intermittent currents adapted to work these instruments may be
produced without actually making and breaking the circuit, as herein-before
described, by suddenly increasing and diminishing the intensity of the current.
"Such currents are termed for the sake of distinction "pulsatory." Intermittent
"and pulsatory currents may be of two kinds, accordingly as the electrical impulses
"have all the same polarity, or are alternately positive and negative. In the
"foriner case they are termed "direct," in the latter "reversed" currents. These
"distinctions are graphically illustrated in Figures 6 and 7.
$4
v
#
.
"Second plan, to which no claim is made otherwise than in claiming clauses
"hereunto annexed,
"In order to secure communication in both directions upon a single circuit, this
"second plan was devised, and it is illustrated in Figures 8, 9, and 10. In these
« Figures the instruments employed are similar to thosa shown in Figures 1. 2. 3. 4.

page_text: "and 5, and like instruments are denoted by like letters; but instead of connecting
"the transmitting instruments T, T, T, &c., directly with the receiving instru-
ments R, R¹, R, &c., as in Figures.3, 4, &c., they are connected with the primary
"wires of an induction coil I, of usual construction, and the currents induced in the
secondary wires of the coil are directed to the receiving instruments R, R¹, R*, &c.,
" on the line wire. By this arrangement the receiving instruments at the terminal
"staticus, Figures 8 and. 10, are connected directly with the earth at G, and signals
"made at any one station appear at all the stations on the circuit. On this plan
"therefore two or more messages may be sent simultaneously over a single circuit
in the same or in opposite directions.
"Third plan, to which no claim is made otherwise than in the claiming clauses
"hereunto annexed.
:. :.
i ...
In the methods heretofore described, employing intermittent currents of
"electricity, the limit to the number of signals that can be sent simultaneously
"over the same wire is very speedily reached, for when a number of transmitting
"instruments having different rates of vibration are simultaneously making and
breaking the same circuit, the effect upon the main line is practically equivalent
" to one continuous current. In addition to this objection local and main batteries
are required at every station on the line. Similar difficulties are experienced in
employing pulsatory currents. To obviate these difficulties the plan of using an
"undulatory current of electricity as described in this part of the Invention was
".devised.
11
"
It has long been known that when a permanent magnet is caused to approach
"the pole of an electro magnet a current of electricity is induced in the coils of the
latter, and that when it is made to recede, a current of opposite polarity to the
first appears upon the wire. When therefore a permanent magnet is caused to
vibrate in front of the pole of an electro maquet an undulatory current of
electricity is induced in the coils of the electro magnet, the undulations of which
correspond in rapidity of succession to the vibrations of the magnet in polarity
"to the direction of its motion, and in intensity to the amplitude of its vibration,
or rather to the velocity, of its motion. A current of this character is graphically
represented in line 3, Figure 7, Sheet 1. When the permanent inagnet is caused
"to vibrate in front of the pole of an electro-magnet, which is placed in circuit with
a voltaic battery, the undulatory current induced by the vibration of the perma-
"nent magnet is superposed upon the voltaic current. When the induced impulse
at
"
It
to
▲ of similar polarity to the voltaic currents it serves to strengthen the intensity
" of the latter, but when it is of opposite polarity it tends to neutralize the voltaic
"-current. In such an arrangement the resultant effect of the vibration of the
permanent magnet is to throw the battery currents into waves, as in line 3,
Figure 6, by alternately increasing and diminishing the intensity of the current.
"Such increase and diminution in the intensity of the current does not take place
"with the suddenness characteristic of a pulsatory current (see line 2, Figure. 6),
but is proportional to the increase and diminution of the density of the air
during the vibration of the inducing body.
M
...
"The various kinds of electrical currents denominated intermittent, pulsatory,
" and undulatory, are graphically represented in Figures 6 and 7. In Figure 6 the
* currents are direct, that is, the electrical impulses 63, 63, 63, &c., are all of the same
"polarity, either positive or negative, and in Figure 7 the the currents are
reversed," that is, the electrical impulses are alternately positive and negative.
Direct Intermittent Current (shown in line 1, Figure 6).-The impulses 63, 63
&c., are all of positive or all of negative electricity, and the vertical thickness of
"the lines 62, 63, &c., measured from the zero line 2, s, represents. the intensity of
"the current of the part observed. The horizontal extension of the line b' indicates
"the duration of the electrical impulse, and the horizontal extension of the space fi
"shows the length of time the current is absent from the circuit.
45
"Reversed Intermittent Current (shown ia line 1, Figure 7).-Impuses of positive

page_text: "
" vice versa.
zero line ¹¹, and the impulses b³, d², are respectively positive and negative, or
"Direct Pulsatory Current (shown in line 2, Figure 6).—The current of electricity
represented is continuous, but it changes suddenly in intensity, the elevations
bd, &c., indicating the impulses of maximum intensity, and the depressions c²²
"the impulses of minimum intensity. As before the vertical thickness of the line
"indicates the strength of the current.
15
"
"
at.
"Reversed Pulsatory Current (shown in line 2, Figure 7).-The impulses b²; d²,
are alternately positive and negative without any break in the continuity of the
current.
"Direct Undulatory Current (shown in line 3, Figure 6). As before, the vertical
"thickness of the line represents the strength of the current, the elevations 6º, 6³,
" &c., express the impulses of maximum intensity, and c³, c, &o, those of minimum
intensity. The changes of intensity, as illustrated in line 3, do not occur with the
"suddenness characteristic of pulsatory currents, as shown in line 2, but are
proportional to the changes in the density of the air during the production of a
" sound.
"
"Reversed Undulatory Current (shown in line 3, Figure 7).-The elevations b², 6²,
" &c., indicate impulses of positive, and the depressions d', d', impulses of negative
electricity, the vertical thickness of the portions 6, d, indicating the intensity of
"the positive or negative impulse at the part observed. The oscillations of the
"current above and below the zero line correspond to the increase and diminution
"of the density of the air during the production of a sound, hence the elevations
6,6&o, correspond to condensations of air, and the depressions d, d², &c., to
rarefactions, the intensity of the positive or negative impulses being proportioned to
the degree of density or rarity of the air.
"
"
4. The differences between intermittent pulsatory and undulatory currents will be
more clearly understood by describing and illustrating the condition of the electrical
current when tho attempt is made to transmit two musical notes simultaneously,
"first upon one plan, and then upon the others. Let the interval between the two
" sounds be a major third, then their rates of vibration are in the ratio of 4 to 5.
"Now when an intermittent current is used the circuit is made and broken four
"times by the armature a, Figure 11, Sheet 1, of one transmitting instrument in
"the same time that five makes and breaks are caused by the armature a¹ of the
" other transmitting instrument; A² and B², Figure 11, represent the intermittent
"currents produced, fou: impulses of B' being made in the same time as five
"impulses of A; 6º, 6º, &c, show where and for how long time the circuit is
"made, and f, f, &c., indicate the duration of the breaks of the circuit. The
"line A + B shows the total effect upon the current when the armatures a, a¹,
Figure 11, are caused simultaneously to make and break the same circuit, and the
"combined effect upon the current passing through the receiver R, shown at A³ + B³,
"Figure 11, is very nearly equivalent to a continuous current.
"
es
Figure 11
When many transmitting instruments of different rates of vibration are simul-
taneously making and breaking the saine circuit, the current upon the main line
"becomes for all practical purposes continuous.
20
"When the armatures a, a, are arranged upon circuit, as shown in Figure 12.
pulsatory currents traverse the coils of the receiving instrument R. The line A'
* represents the pulsatory current due to the action of one armature a, and the
"line B the action due to the other armature a¹; b, b, &c., represent impulses of
"maximum intensity, and c³, c³, &c., impulses of minimum intensity. Four impulses
"of B are made in the same time as five impulses of A, and the line A + B
" represents the total effect upon the current passing through the coils of the
"receiver R when the armatures a and a³ are caused to vibrate simultaneously.
This effect is nearly equivalent to a continuous current of minimum intensity.
"Next consider the effect when undulatory currents are employed. Electrical
"undulations induced by the vibration of a body M, Figure 13, capable of inductive
* action can be represented graphically by the same sinusoidal curve which expresses

page_text: st
"the vibration of the inducing body itself, for as above stated, the rate of oscillation
" in the electrical current is the same as that in the-inducing body. The intensity
" of each induced impulse is proportional to the velocity of the motion of the
inducing body, and tho polarity of each induced impulso depends upon the direction
"of the motion of the inducing body to or from the pole of its electro magnet. The
"sinusoidal curves A' and B³, Figure 13, represent graphically the electrical unda-
"-lations induced in a circuit by the vibration of permanent magnets M and M², or
other bodies capable of inductive action.
"
63
"
a-
##
50
"The portions 62, 63, &c, represent impulses of positive electricity, and c³, d³, &c.,
impulses of negative electricity. The horizontal line 21, 2³, represents the zero of
current, and the vertical distance of any portion of the curve b³ or d from the
zero line expresses the intensity of the positive or negative impulse at the part
observed..
..
"The vibrations represented by the sinusoidal curves B and A², Figure 13, are
"in the ratio aforesaid, of four to five, that is, four oscillations of B' are made in the
same time as five oscillations of A. The combined effect of A and B, when
"induced simultaneously on the same circuit, is expressed by the curve A³ + B³,
Figure 13, which is the algebraical sura of the sinusoidal curves A and B. In
Figure 14, the permanent magnets M and M' are caused to vibrate in front of the
poles of electro magnets e, e, placed. in circuit with a battery B; by such an
The lines A' and B'
arrangement the battery current is thrown into waves.
represent the undulatory currents produced respectively by the vibrations of M
and M', and as in the other instances, four impulses of B³ are made in the same
time as five impulses of A; the elevations 63, 6, &c., indicate impulses of maximum
intensity, and the depressions c³, c³, &a, impulses of minimum intensity; the
vertical distance of any portion of the curve o³, d, from the zero line s¹, s¹;
expresses the intensity of the current at part observed; the line A³ + B³ expresses
the resultant effect upon the current when the permanent magnets M, AI, are
caused to vibrate; the curves A' + B², Figures 13 and 14, also indicate the
"actual motion of the air when the two magnets M, M', are vibrated simultaneously.
Thus, when electrical undulations of different rates are simultaneously produced
upon the same cirenit, the effect is exactly analogous to that occasioned
"in the air by the vibration of the inducing bodies. Hence the co-existence upon
a telegraphic circuit of electrical undulations, corresponding to sounds of different
pitch, is manifested not by the obliteration of the vibratory character of the
"current, as with intermittent and pulsatory currents, but by peculiarities in the
shapes of the electrical undulations, or in other words by peculiarities in the shapes
" of the curves which represent those undulations.
st
1
simultaneously
.
"
"There are many ways of producing undulatory currents of electricity dependent
"for effect upon the vibration or motion of bodies capable of inductive action. A
"few of the methods that may be employed are as follows:-Whon a wire through
"which a continuous current of electricity is passing is caused to vibrate in the
"neighbourhood of another wire, an undulatory current of electricity is induced in
the latter. When a cylinder, upon which are arranged bar magnets, is made to
rotate in front of the pole of an electro magnet an undulatory current of electricity
" is induced in the coils of the electro magnet.
"Undulations are caused in a voltaic current by the vibration or motion of bodies
capable of inductive action, or by the vibration of the conducting wire itself in
the neighbourhood of such bodies. Electrical undulations may also be caused by
alternately increasing and diminishing the resistance of the circuit, erby
alternately increasing and diminishing the resistance-of-the-circuit, or by
alternately increasing and diminishing the power of the battery. The internal
"resistance of a battery is diminished by bringing the voltaic elements nearer
together, and increased by placing them farther apart; the reciprocal vibration of
"the elements of a battery therefore occasions an undulatory, action in the voltaic

page_text: "
"The external resistance may also be varied, for instance, let water or some other
liquid of high resistance form part of a voltaic circuit, then the more deeply the
conducting wire is immersed in the water or other liquid, the less resistance does
"the liquid offer to the passage of the current, hence the vibration of the conducting
"wire in water or other liquid included in the circuit occasions undulations in the
“current. The vertical vibration of the elements of a battery in the liquid in
" which they are immersed produces an undulatory action in the current by
aternately increasing and diminishing ▲ of the battery.
the power
"In illustration of one method of creating electrical undulations a form of apparatus
is shown in Fig. 15. It is preferable to employ for this purpose an electro magnet
E, Figure 15, having a coil upon only one of its legs. A steel spring armature A
is firmly clamped by one extremity to the uncovered legh of the magnet, and its
free end is allowed to project above the pole of the covered leg. The armaturo A
can be set in vibration in a variety of ways, one of which is by wind, and in
"vibrating it produces a musical note of a certain definite pitch.
"
"When the electro magnet E is placed in a voltaic circuit B, E, W, E', B, the
“ armature A becomes magnetic, and the polarity of its free end is opposed to that
"of the magnet underneath. So long as the armature A remains at rest no effect
"is produced upon the voltaic current, but the moment it is set in vibration to
produce its musical note a powerful inductive action takes place and the electrical
" undulations traverse the circuit above described. The undulatory current passing
through the coil of the electro maguet E' causes vibration in its armature A when
"the armatures of the two magnets are normally in unison with one another, but
"the armature A is unaffected by the passage of the undulatory current when the
"pitches of the two armatures are different.
"
3. :
* The instruments shown in Figure 15 are like in plan to the receiving instru-
* ments R, R¹, &c., of Figures 1, 2, 3, 4, 5, 8, 9, 10. ▲ number of instruments may
"be placed upon a telegraphic circuit, as in Figures 16, 17, 18. When the armature
of any one of the instruments is set in vibration, all the other instruments upon
"the circuit which are in unison with it respond, but those which have normally a
different rate of vibration remain silent. Thus if R, Figure 16, is sat in vibration
the armatures of the receivers R, Figures 17, 18, vibrate also, but all the others
on the circuit remain still. So if R¹, Figure 17, is caused to emit its musical note,
" the instruments R', shown in Figures 16 and 18, respond. They continue sounding
so long as the mechanical & of R', Figure 17, is continued, but become silent with
the cessation of its motion. The duration of the sound may be used to indicate
"the dot or dash of the Morse alphabet, and thus a telephonie despatch may be
vibration
interrupting
“ indicated by alternately and renewing the sound.
"
telegraphic
"When two or more instruments of different pitch are simultaneously caused to
"vibrate, all the instruments of corresponding pitches upon the circuit are set in
"vibration, each responding to only that instrument used as a transmitter with
"which it is in unison. Thus the signals of R, Figure 10, are repeated by R, of
Figures 17 and 18, but by no other instrument upon the circuit. The signals of
R. Figure 18, by R¹, Figures 16 and 17, and the signals of R', Figure 17, by R³,
Figures 16 and 18, whether R, Figure 16, R¹, Figure_18, and R³, Figure 17, are
successively or simultaneously caused to vibrate. Hence by these instruments
"two or more telegraphic signals or messages may be sent simultaneously over
"the same circuit without interfering with one another, & single battery B being
"used for the whole circuit. These instruments may be used for the simultaneous
transinission of musical notes differing in loudness as well as a pitch.
"
•
"When the armature A, Figure 15, is set in vibration, the armature A¹ responds
not only in pitch but in loudness. Thus when A vibrates with little amplitude,
a very soft musical note proceeds from Al, and when A vibrates forcibly, the
amplitude of the vibration of A' is considerably increased, and the resulting sound

page_text: " becomes louder. So if R and R', Figure 16, are sounded simultaneously (R loudly
"and R¹ softly) the instruments R, Figures 17 and 18, repeat loudly the signals
66
"
of R, Figure 16, and R¹, Figures 17 and 18, repeat softly those of R, Figure 16."
"FOURTH PLAN,
18
« Which is not claimed further than is indicated by the claims made in the claiming
"clauses hereunto annexed, and it is to be noted that no claim is made to the use of
telephonic apparatus, wherein a membrane like gold-beaters skin is used in com-
bination with an electro magnet excited by a battery which is arranged in the
"main circuit or line wire, inasmuch as such a membrane was mentioned in
descriptions published in England prior to December 9, 1876, and as such a
* membrane is of small utility owing to its uncertainty of action caused by
changes due to wear or moisture, or atmospheric influences.
"
"6.
In the plans so far described a separate instrument is employed for every pitch,
"and the electric vibrations for different pitches are combined upon the wire, each
armature being capable of transinitting or receiving. but a single note, and thus
"as many separate instruments are required as there are messages or musical notes
"to transmit.
"In this part of the Invention a single instrument is employed, the arniature of
"which can be set in vibration by a musical instrument, or by the tones of the
"human voice, or by any sound whatever.
"
"This fourth plan is represented in Figures 21, 22, and 23, wherein is shown a
single telephone at each station in place of the transmitting and receiving
instruments heretofore described, the telephones being illustrated separately in
Figures 19 and 20.
One of the ways in which the armature A, Figure 15, may be set in vibration
has been stated to be by wind. Another mode is sbewn at Figure 10, whereby
Emotion can be imparted to the armature by the human voice, or by means of a
musical instrument, or by sounds of any kind.
A
The armature A, Figure 19, is fastened loosely by one extremity to the
" uncovered leg of the electro-magnet E, and its other extremity is attached to
"the centre of a stretched membrane n. A cone is used to converge sound
"vibrations upon the membrane. When a musical note is made in the neighbour-
"hood of the membrane n it is set in vibration, the armature A is forced to partake
"of the motion, and thus electrical undulations are created upon the circuit G, B,
E, W, E', G. The armature A' is thus thrown into synchronous vibration with
"the armature A emitting a musical note of similar pitch to that which originated
"the vibration of armature A. If two or more musical notes be simultaneously
"sounded in the neighbourhood of the cone C, the resultant motion of the air
"is copied by the membrane n to which the armature A is attached, and this
4.armature A, acting inductively upon the current traversing the coils of the electric
magnet E, occasions an increase and diminution in its intensity, and the arinature A¹
is thrown into vibration by the varying attraction of the electro magnet E¹ to
which it is attached, and thus imparts to the air at n' a fac simile copy of the
"motion of the air that noted upon the membrane n; hence two or more musical
* notes or telegraphio messages can be sent simultaneously along a single circuit
"from one station to another by means of one instrument at each station.
41
* "Instead of the cone membrane and armature shewn in Figure 19, a plate of thin
"steel, such as is shewn at A in Figure 31 of the Drawings hereunto annexed, may
"with greatly increased advantage be used as an armature; the vibrations of the
plate in front of the magnet occasioned by the motion of the air during the
production of a sound changes the intensity of the current, as hereinbefore
described, and occasions a similar motion in a similar steel plate in front of another
electro-magnet at another station in the circuit. Such a plate is shewn in Figure 20
“ and marked A³, it being attached to a frame F. The telephones shewn in
E1
"

page_text: 1.
"
"
Figures 21 to 20 are of the kind shown in Figure 20. This Invention is not
limited however to the use of a steel plate, but includes within its scope ang
equivalent plate capable of inductive action upon a current of electricity. In this
plan an operator at station, Figure 21, may send a telegraphic message on a certain
pitch while another operator at another station, say Figure 22, is transmitting
"another message on a different pitch, and both sounds will be audible at all the
"stations in the circuit.
"
"
:
"The receiving operators will pay attention to signals of only one pitch, hence
by this plan the simultaneous transmission of a number of telegraphic messages
over a single circuit in the same or both directions, with a single main battery for
"the whole circuit, and a single telephonic instrument at each station is rendered
"possible. Whatever sound is made in the neighbourhood of any telephone, say,
Te, Figure 21, is echoed in fao simile by the telephones T, e, of all the other
stations; hence, this fourth plan is also adapted for the entirely new use of trans-
mitting intelligibly the exact sounds of articulate speech.
16
et.
" To
convey an articulate message, it is only necessary for the operator to speak
in the neighbourhood of a telephone, say, T, e, Figure 21, and for the receiving
operator at another instrument, say, T, e, Figure 23, to listen.
"All the methods of producing undulatory currents of electricity herein before
" described may be employed in producing the undulations by which to transmit
". articulate messages. For instance, the vibrations of a membrane may cause a
1. platinum wire to vibrate in water or other liquid of high resistance included in
the circuit, and hence will occasion changes in the intensity of the current,
traversing the circuit proportional to the changes in the density of the air, which
originally gave rise to the vibrations of the membrane, and hence the sounds
"uttered in the neighbourhood of that machine membrane will be reproduced from a
telephone on a distant part of the circuit.
"
"
In the fifth plan of the Invention, illustrated in Figures 24, 25, and 26, which
" is not claimed further than is indicated by the claims made in the claiming clauses
" hereunto annexed, the battery is omitted and a permanent magnet M is substituted
" for the soft iron core of the electro magnets used in the other telephones. Or
"the coils, shewn in Figures 24, 25, and 26, may be induction coils of usual con-
"struction, local batteries being placed in circuit with the primary wires, so as to
magnetize the soft iren cores of the coils. The undulations induced in the
." secondary wires by the vibration of the plates A³ being directed upon the line
" wire.
"
"
"The sixth plan of the Invention, to which no claim is made otherwise than in
"the claiming clauses hereunto annexed, is represented in Figures 27, 28, and 29.
Figure 27 being a side view of a receiving instrument R, having a magnet E and
"armature A, as before described, and provided also with a vibratory circuit
"breaker V. This circuit breaker is designed for the purpose of enabling the
" armature A to open or close a local circuit through the medium of the circuit
"breaker V. This circuit breaker consists of a light metallic lever, normally
resting upon the point 5, preferably adjustable, so as to close a local circuit.
"The extremity of the circuit breaker overhangs the free end of the armature A.
When the armature A is thrown into vibration by the action of magnet E, the
"circuit breaker is lifted from the point 5, and it does not return until the cessation
"of the vibration of the armature A.
"
"
SE
In Figure 28 an arrangement is shewn whereby the lifting of the circuit breaker
opens a local circuit, in which is placed a Morse sounder 6 or other electrical
apparatus.
Ve
"In Figure 29 the circuit breaker V, normally "short circuits" the battery B,
cutting off the current from the Morse sounder 6 or other apparatus, so that the
lifting of the circuit breaker V permits the current from the battery B to
"actuate telegraphic instrument 6. The vibrating circuit breaker V may be
changed in construction, it only being necessary that it have normally a slower
".rate of vibration than the armature A by which it is vibrated.
14.

page_text: 12
Figuro 30 represents an arrangement of transmitting instruments T, T', T', &c.,
"and receiving instruments R, R, &c., and vibratory circuit breakers V, VI, &c.,
"similar to those shewn in Figures 1, 2, 27, designed to produce automatically at
"the receiving end of the line a fac simile of whatever characters or marks are
presented at the transmitting ends. In this plan the messages or marks to be
copied may be written or printed in non-metallic ink on a metallic surface F, o,
"shewn in dotted lines (preferably tin foil), or impressed upon the same.
This
"
4.
"
metallic surface is placed upon a suitable metallic support S, preferably made as
B roller, having its axis at 7 connected with the battery B and the earth C. At
"the receiving end a similar support. S' is connected in circuit with the battery B'
and the vibratory circuit breakers V, V, V, &c., and on this support is placed a
piece or strip of chemically prepared paper, P, a, shewn in dotted lines.
The metallic surface F, o, on which is written the message to be transmitted is
"moved between the support S and the ends.of a series of wires 8, 9, 10, 11, 12,
13, &c., such ends being held by a non-metallic holder or bar 14. The wires 8, 9,
"10, &c, communicate with the armatures a of transmitters T, T¹, &c., similar to
the transmitter T, shown in Figure 1.
* At the receiving end of the circuit the ends of a similar arrangement of wires
":15, 16, 17, 18, 19, and 20, are held in place by a. non-metallic holder 21, so as
"to rest upon the chemically prepared paper P, u.
"The metallic surface F, o, and the chemically prepared paper P, a, are each
"moved in the direction of the arrows under their respective series of wires, but
"not necessarily at equal speed, and the characters or marks on the foil are copied
on the prepared paper.
=
When the end of any of the wires at the transmitting end, say wire 8, rests
upon the metallic foil, a communication is established between the battery B and
the armature a of the transmitter T; the platinum rivet r, as heretofore described,
"vibrates and makes and breaks contact with the point m, so that an intermittent
"current of electricity appears upon the line wire W. So long then as the wire 8
"rests on the metallic surface F, o, the currents of a pass through 7, S, F, o, 8, r, m,
" to the line wire W, and thence by branches through the receiving instruments R,
R, &c., to the earth at C¹.
I
"The armature of the receiving instrument R, which is in unison with the
"* armature a of the transmitter T, is thrown into vibration by the passage of the
"-intermittent current, but the armatures of the other transmitting instruments R',
R³, &c., having a different rate of vibration from the armature of T do not
respond.
"
16
"The armature of the receiving instrument R in the course of its vibration lifts
"the spring lever V, breaking the circuit B', S', P, a, 15, V, B¹. So long then as
"the end of the wire 8 rests upon the metallic surface F, o, the local circuit in which
"the wire 15 is placed remains open, and thus no mark is made upon the paper
P, a, under wire 15.
a
."
L
-
'
"When, during the movement of the metallic surface F, o, a portion of the non-
"metallic ink comes under the end of the wire 8, the connection between the battery
"Band transmitter T is broken, the receiver R becomes silent, the spring lever V
"returns to its normal position, closing the circuit above described, and a mark is
made upon that part of the cliemically prepared paper P, a, under wire 15.
"Each wire 9, 10, &c., operates in a like inanner to the wire 8, and the wires 16,
17,18, &c., operate as described for wire 15.
ts
"
Any of the ordinary chemically prepared paper used in connection with ordinary
systems of chemical or autograph telegraphs may be used.
Referring again to the fifth plan, the magnet may be of the horse-shoe forin, as
"shewn at 24, in Figure 31, and the coils of insulated wire 25 may surround soft
" iron cores or pole pieces 26 screwed or otherwise fastened to the ends of the
magnet 24. The cores or pole pieces are placed near the face of the metallic plate
A, it being attached to a cup-shaped block 28 having a central orifice 29 for the
" recention of a speaking or hearing tube to convey sounds to or from the plate A$.

page_text: The magnet is attached to a stud 30, adapted to be moved in suitable grooves in
the base 31 by means of a screw 32 having its end connected with the stand, the
body of the screw being fitted to turn in a screw threaded stud. The movements
of the screw are just the distance between the pole of the magnet and the plate
A³, and permit the poles to be placed almost in contact with the plate. The coils
may be placed about the end of the magnet 24, and the soft iron pole pieces be
omitted.
"Figure 32 represents in perspective a telephone of the kind shown in Figure 31,
when placed within a sounding box 33. The coils will, preferably, be very thin,
and be placed at the extremity or extremities of the magnet. One, two, or more
magnetic poles with coils may be placed near a plate to intensify the effect.
"The soft iron core and coil may be attached to the plate iustend of the magnet,
or the core may be placed upon the plate and the coil on the magnet, or vice versa,
the magnet may be made to vibrate instead of the plate.
"
Having now described and particularly set forth the nature of the said Invention,
and the manner of carrying the same into effect, I would have it understood that
what I claim is,—
shore
".
"First. The combination, substantially as set forth and described respectively in
"the fourth and fifth plans before referred to, but subject always to the disclaiming
"notes of a permanent magnet (or other body capable of inductive action) with a
.closed circuit, so that the vibration of the one shall occasion electrical undulations
"in the other or in itself; and this I claim whether the permanent magnet be set in
"vibration in the neighbourhood of the conducting wire forming the circuit, or
"whether the conducting wire set in vibration in the neighbourhood of the
permanent magnet, or whether the conducting wire and the permanent magnet,
"both simultaneously, be set in vibration in each other's neighbourhood.
* Second. The method of transmitting vocal or other sounds electrically by
causing the intensity of an electrical current generated and described in the
"fourth and fifth plans, but subject always to the disclaiming notes to vary in a
manner proportional to the variations of density produced in the air by the said
"sounds.
65
Third. The method of transmitting vocal or other sounds electrically by causing
"the intensity and polarity of an electrical current generated as described in the
"fourth and fifth plans, but subject always to the disclaiming notes, to vary in a
manner proportional to the velocity and the direction of motion of the particles
"of air during the production of the sounds.
"
M
•
"Fourth. The union upon and by means of an electric circuit of two or more
telephones when constructed for operation, substantially as described in the
"fourth and fifth plans, but subject always to the disclaiming notes, so that if the
plate armature of any one of the said instruments be moved in any manner the
" armatures of all the other telephones upon the same circuit will be moved in
"like manner; and if the transmitter armature he moved or vibrated by sound,
"like sounds will be produced by the motion or vibration of the armature of the
"other telephones upon the circuit.
"Fifth. In a system of electric telegraph or telephony, consisting of transmitting
" and receiving instruments, such as were described in the fourth and fifth plans,
but subject always to the disclaiming notes, united upon an electric circuit, I
"claim the production in the armature of each receiving instrument of any given
"motion by subjecting said armature to an attraction varying in intensity, however
such variations may be produced in the magnet; and hence I claim the production
" of any given sound or sounds from the armature of the receiving instruments,
"such as are above mentioned by subjecting said armature to an attraction varying
"in intensity in such manner as to throw the armature into that form of vibration
« which characterises the given sound or sounds.

page_text: * Sixth. The combination in the manner described in the fourth and fifth placз.
"but subject always to the disclaiming notes, of an electro magnet with a plate
" of iron or steel or other material capable of inductive action, which can be
"thrown into vibration by the movement of surrounding air, or by the attraction
" of a magnet.
"'
"Seventh. In an electric telephone the combination with the plate of a magnet
having coils upon the end or ends of the magnet nearest the plate, substantially
." as described in the fourth and fifth plans, but subject always to the disclaiming
..
* notes.
-
Eighth. In an electric telephone the combination with a permanent magnet
"and plate armature of a soft iron pole piece forming the core for the coil,
"substantially as described" in the fourth and fifth plans, but subject always to
the disclaiming notes.
In. witness whereof, I, the said William Morgan-Brown, have bereunto set
my hand and seal, this Twenty-fourth day of January, in the year of our
*Lord One thousand eight hundred and seventy-eight.
WILLIAM MORGAN-BROWN.