IMPROVEMENTS IN TELEGRAPHIC AND TELEPHONIC APPARATUS "
Year: 1882

page_text: LETTERS PATENT to Alfred Charles Brown and Henry Alfred Charles
Saunders both of 66 Old Broad Street in the City of London for an Invention
of "IMPROVEMENTS IN TELEGRAPHIC AND TELEPHONIC APPARATUS
"
PROVISIONAL SPECIFICATION left by the said Alfred Charles Brown and
Henry Alfred Charles Saunders at the Office of the Commissioners of Patents
on the 16th September 1882.
ALFRED CHARLES BROWN and HENRY ALFRED CHARLES SAUNDERS both of
66 Old Broad Street in the City of London "IMPROVEMENTS IN TELEGRAPHIC
AND TELEPHONIC APPARATUS
"
This Invention has for its object improvements in telegraphic and telephonic
apparatus.
Our improvements are applicable where several "Subscribers" make use of one
line wire for telephonic communication in the manner explained in the Specification
of a former Patent granted to us N° 1896 in the year 1882; In this arrangement
each subscriber is provided with a step by step instrument in which motion is given
by means of a magnet and armature to a wheel and axis. These parts in all the
instruments in circuit can be set in motion by currents transmitted by any
subscriber and stopped in any required position. The effect of this operation is
two fold, first to establish telephonic communication between the operator and the
subscriber to whom he wishes to talk; and second to prevent interference by others
with the conversation.
According to our present Invention in place of transmitting the actuating currents
as formerly by successive movements of the operator's plunger or finger key, we
produce the current automatically by means of an automatic transmitter which is
started by a single current passed into the line when the operator presses his key.
The automatic transmitter then sends a series of alternating currents more than
sufficient in number to produce a complete revolution in all the instruments on the
circuit.

page_text: The operator can however stop the instruments simultaneously in any position
which he may require and this he does by increasing the resistance of the circuit.
The release of the finger key causes the resistance of the operators receiving
telephone and secondary coil to be added to the circuit and this added resistance
so weakens the alternating currents that they are no longer competent to propel the
instruments.
When the instruments are not thus stopped at an intermediate point by the
operator they run on to the zero point and there stop notwithstanding that the
alternating currents may still be passing in the line; this result which ensures
the instruments being kept in unison is brought about by means which we will
presently describe.
The finger key which we now use operates as formerly when pressed in to put
the line to earth and there being opposed batteries at the terminal stations a
current then passes but in our prevent key the contact lever does not dwell
upon the earth contact but passes beyond it so that only a momentary current
passes although the pressure upon the key is continued, a spring is also added
and a contact lever of the key when pressed in comes against the spring and
establishes a short circuit which relieves the line of the resistance of the receiving
telephone and secondary coil.
The automatic transmitter which the key current calls into action consists of an
electro magnet having an armature attached to a lever. The current causes the
magnet to attract the armature and the movement of the lever causes the line wire
to be put to earth through the coils of another electro magnet whilst it opens the
previously existing connection through the coils of the first mentioned magnet to
the battery and earth. The result of thus removing the home battery from the
circuit is to render the distant battery active in the line and it causes the second
electro magnet which has just been brought into circuit to attract its armature.
Now the arrangement of this is an in an ordinary electric bell except that it is
made to vibrate somewhat more slowly. The armature in its vibrations makes
and breaks the line circuit in which the distant battery is included and these makes
and brakes cause the step by step instruments of the several subscribers to be
propelled. The automatic transmitter runs, as already stated, long enough to send
more currents through the line than are requisite to produce complete rotation in
the instruments. It continues to run in fact until the armature of the first
mentioned magnet is drawn off by its spring and the original connections thereby
reestablished.
Now this return of the lever is delayed for a considerable time by a peculiar
contrivance which we will now explain. The lever carries a disc of flexible india
rubber which when the armature is attracted is brought down upon a flat surface
and when the spring attempts to draw the lever back a vacuum is formed beneath
the disc which resists the spring. The spring is thus controlled until time enough
has elapsed for air to find its way beneath the surface of the disc. The parts are
so adjusted that this time is sufficiently long for the requirements of the automatic
transmitter. A similar arrangement is applicable in other telegraphic instruments
in which it is required to delay the return of the armature of an electro magnet or
other like part and another application will be presently described.
The way in which the armature lever controls the contacts is as follows;-It
carries upon it a straight wire spring which is in permanent connection with the
line wire. When the armature is away from the magnet the free end of the wire
spring is retained in a notch in the edge of a metal plate which is connected
through the coils of the magnet with the battery and through the battery to earth.
The wire spring is so flexible that the movement of the armature lever is nearly
complete before the spring leaves the notch in the plate and it is then struck out
of it by a finger carried upon the lever. The spring then drops into another
similar notch lower down but in another plate with which it makes contact and
the circuit of the home battery is then open but that of the distant battery is
complete. It passes through the line wire, the spring, the second notched plate,

page_text: the coils of the second electro magnet (or that with the trembling armature) and so
to earth. When the india rubber disc or sucker yields to the armature spring a
finger on the lever strikes the wire out of the lower notch and it passes to the upper
thereby reestablishing the normal contacts.
It has yet to be explained how it is that the step by step instruments are all
made to stop at the zero position or that in which any subscriber is able to
commence to work.
The ratchet wheel of the propelment has a notch or tooth omitted at the zero
point and when the driving pawl gets to this point it simply moves to and fro upon
the wheel without rotating it.
If the driving pawl always moved over the same distance the instruments
would never pass the zero point; but there is an arrangement which causes the first
movement of the armature and driving pawl after a pause to be longer than the
movements taking place subsequently in rapid succession.
For this purpose the armature lever of each step by step instrument has a hook
upon it which engages with a similar part attached to a sicker like disc of india
rubber resting upon a flat surface. Each time that the armature is drawn off by
its spring, as soon as it has moved a distance sufficient for the ordinary propelment,
it is checked by the sucker and retained and if another current quickly follows
through the coils of the magnet it never gets fully back. But when there is a
pause between the currents, such as occurs when the automatic transmitter ceases
to work, then the armature spring has time to overcome the sucker or rather the
sucker itself yields. The armature then goes fully back and its next advance is a
step of double length.
In place of the usual retaining ratchet and pawl we retain the propelinent
ratchet during the backward movement of the driving pawl, simply by the
frictional pressure of a spring operating upon the surface of a plain wheel or disc.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alfred Charles Brown and Henry Alfred Charles Saunders in the
Great Seal Patent Office on the 16th March 1883.
ALFRED CHARLES BROWN and HENRY ALFRED CHARLES SAUNDERS both of
IMPROVEMENTS IN TELEGRAPHIC
66 Old Broad Street in the City of London
AND TELEPHONIC APPARATUS
"
66
This Invention has for its object improvements in telegraphic and telephonic
apparatus.
Our improvements are applicable where several "Subscribers "make use of one
line wire for telephonic communication in the manner explained in the Specifica-
tion of a former Patent granted to us N° 1896 in the year one thousand eight
hundred and eighty-two. In this arrangement each subscriber is provided with a
step by step instrument in which motion is given by means of a magnet and
armature to a wheel and axis. These parts in all the instruments in circuit can
be set in motion by currents transmitted by any subscriber and stopped in any
required position: The effect of this operation is two fold, first to establish
telephonic communication between the Operator and the subscriber to whom he
wishes to talk, and second to prevent interference by others with the conversation.
According to our present Invention in place of transmitting the actuating currents
as formerly by successive movements of the operators plunger or finger key, we
produce the currents automatically by means of an automatic transmitter which is
started by a single current passed into the line when the Operator presses his key.
The automatic transmitter then sends a series of alternating currents more than
sufficient in number to produce a complete revolution in all the instruments on the
circuit.
The Operator can however stop the instruments simultaneously in any position
which he may require and this he does by increasing the resistance of the circuit.
The release of the finger key causes the resistance of the Operators receiving tele-
phone and secondary coil to be added to the circuit and this added resistance so
weakens the alternating currents that they are no longer competent to propel the
instruments.
When the instruments are not thus stopped at an intermediate point by the
Operator they run on to the zero point and there stop notwithstanding that the
alternating currents may still be passing in the line, this result which ensures
the instruments being kept in unison is brought about by means which we will
presently describe.
The finger key which we now use operates as formerly when pressed in to put
the line to earth and there being opposed batteries at the terminal stations a
current then passes. But in our present key the contact lever does not dwell upon
the earth contact but passes beyond it so that only a momentary current passes
although the pressure upon the key is continued. A spring is also added and the
contact lever of the key when pressed in comes against the spring and establishes a
short circuit which relieves the line of the resistance of the receiving telephone and
secondary coil.
The automatic transmitter which the key current calls into action consists of an
electro magnet having an armature attached to a lever. The current causes the
magnet to attract the armature and the movement of the lever causes the line wire
to be put to earth through the coils of another electro magnet whilst it opens the
previously existing connection through the coils of the first mentioned magnet to
the battery and earth,

page_text: The result of thus removing the home battery from the circuit is to render the
distant battery active in the line and it causes the second electro magnet which has
just been brought into circuit to attract its armature. Now the arrangement of
this is as in an ordinary electric bell except that it is made to vibrate somewhat
5 more slowly. The armature in its vibrations makes and breaks the line circuit in
which the distant battery is included and these makes and breaks cause the step by
step instruments of the several subscribers to be propelled.
The automatic transmitter runs, as already stated, long enough to send more
currents through the line than are requisite to produce complete rotation in the
instruments. It continues to run in fact until the armature of the first men-
tioned magnet is drawn off by its spring and the original connections thereby
re-established.
Now this return of the lever is delayed for a considerable time by a peculiar
contrivance which we will now explain. The lever carries a disc of flexible india
rubber which when the armature is attracted is brought down upon a flat surface.
and when the spring attempts to draw the lever back a vacuum is formed beneath
the disc which resists the springs. The spring is thus controlled until time enough
has elapsed for air to find its way beneath the surface of the disc. The parts are so
adjusted that this time is sufficiently long for the requirements of the automatic
transmitter. A similar arrangement is applicable in other telegraphic instruments
in which it is required to delay the return of the armature of an electro magnet or
other like part and another application will be presently described.
The way in which the armature lever controls the contacts is as follows-it
carries upon it a straight wire spring which is in permanent connection with the
line wire. When the armature is away from the magnet the free end of the wire
spring is retained in a notch in the edge of a metal plate which is connected
through the coils of the magnet with the battery and through the battery to earth.
The wire spring is so flexible that the movement of the armature lever is nearly
complete before the spring leaves the notch in the plate and it is then struck out
of it by a finger carried upon the lever. The spring then drops into another similar
notch lower down but in another plate with which it makes contact and the circuit
of the home battery is then open but that of the distant battery is complete. It
passes through the line wire, the spring, the second notched plate, the coils of the
second electro magnet (or that with the trembling armature) and so to earth.
When the india rubber disc or sucker yields to the armature spring a finger on the
lever strikes the wire out of the lower notch and it passes to the upper thereby re-
establishing the normal contacts.
It has yet to be explained how it is that the step by step instruments are all
made to stop at the zero position or that in which any subscriber is able to
commence to work.
The ratchet wheel of the propelment has a notch or tooth omitted at the zero
point and when the driving pawl gets to this point it simply moves to and fro upon
the wheel without rotating it.
If the driving pawl always moved over the same distance the instruments would
never pass the zero point; but there is an arrangement which causes the first
movement of the armature and driving pawl after a pause to be longer than the
movements taking place subsequently in rapid succession. For this purpose the
armature lever of each step by step instrument has a hook upon it which engages
with a similar part attached to a sucker like disc of india rubber resting upon a flat
surface. Each time that the armature is drawn off by its spring, as soon as it has
moved a distance sufficient for the ordinary propelment, it is checked by the sucker
and retained and if another current quickly follows through the coils of the magnet
it never gets fully back. But when there is a pause between the currents, such as
occurs when the automatic transmitter ceases to work, then the armature spring
has time to overcome the sucker, or rather the sucker itself yields. The armature
then goes fully back and its next advance is a step of double length.
In place of the usual retaining pawl we retain the propelment ratchet during the

page_text: backward movement of the driving pawl, simply by the frictional pressure of a
spring operating upon the surface of a plain wheel or disc.
In order that our said Invention may be most fully understood and readily carried
into effect we will proceed to describe the Drawings hereunto annexed.
66
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a front elevation. Figure 2 is a side elevation and Figure 3 is an
end elevation of the step by step or signal instrument and key with which each
Subscriber" is provided to enable him to place himself in communication with
the "Subscriber "he desires to address. The general arrangement of this instrument
is as described in our former Patent and the application of our present improve-
ments thereto is clearly shewn. Figure 4 is a diagram shewing the connections of
the various instruments provided for each "Subscriber." Figure 5 is a side elevation
of the automatic transmitter or "actuator "at one end of the line. Figure 6 is an
end elevation of the same.
Our signal instrument consists of a step by step motion, composed of an electro-
magnet (D. Figures 1 and 2) whose armature actuates a click arrangement and
ratchet wheel O, which turns the main arbor C one step for each to and fro motion
of the armature. This main arbor C carries a hand to indicate the numbers or
signals of the stations on the dial, and a cam lettered G; a piece of wire projecting
upwards from the ratchet wheel O also forms another cam lettered I. The upper
cam G, when the hand comes to zero, lifts a locking lever H sufficiently to one side
to mechanically clear a collar on the plunger J (see figure 3) so that the latter is
capable of being pressed, but when the hand moves from zero, the cam G releases
the lever H which then falls by gravity against the stop F (figure 1) in which
position it locks on the upper or lower side of the collar or plunger J, according as
to whether or not the latter was pressed prior to the hand moving from zero-This
collar on J also comes in contact, when pressed, with one of a pair of ebonite studs
fixed in a friction lever key K (figures 1 to 3) and moves the latter over for the
remainder of its stroke. This lever turns at one end on a shoulder screw insulated
from the main framework, and at the other end bears on, and when pressed, rubs
along a compound pillar L. P. E. (composed of alternating pieces of brass and
insulating material) and in doing so successively makes contact with the three
brass contact pieces L. P. E. A piece of spring wire S is also fixed to the bottom of
this insulating pillar and projects out in such a way as to make contact with
lever K, when it is pressed as far as the bottom of piece P and continue in contact
therewith to the bottom of its stroke, breaking at about the same point on its
release. The second cam I, when the hand comes to the number or signal of the
station in which that particular instrument is to be placed, comes into contact with,
and slightly lifts the end of a light spring N fixed by an insulating attachment to
the main framework. At all other times however, this spring N rests on, and
makes contact with a stud Q, also insulated from the main framework.
The connections are as follows:-Referring to figures 1 and 4 it will be seen
that the line circuit comes in by terminal L', passes through the electro magnet
coils D, and goes on to the terminal marked S¹ and T. C. and to the key marked K
together. From terminal S' and T. C. (see figure 4) it goes on through the
telephone and secondary to terminal L² S2 or outgoing line. This part of the circuit,
however, consisting of the speaking instruments, is normally kept short circuited,
first by the switch hook and second by an automatic short circuit road, through
the signal instrument itself, starting from terminal S¹ and T. C. or one side of the
speaking instruments, vid key K to contact piece L on pillar L. P. E. with which
contact piece K is normally in contact. From here the road goes on to spring N
which is normally in contact with its screw stud Q, from whence a wire leads on
to terminal L². S. or the other side of the speaking instruments. It will thus be
seen that the first of these short circuit roads is at the option of the subscriber to
break by taking off his telephone, but the second road (that through the signal) is

page_text: out of his control when the key plunger J is locked by the lever H. The local
connections are as follows. A wire is run from the Cu pole of the local cell to
terminal L. C, on the signal. From here it goes on to the stud R (Figures 1 and 4),
which is fixed by an insulating attachment to the lower plate of the main
framework, and forms a mechanical stop for, and makes an electrical contact with,
the click-rod on armature pivot M, when the armature is right away from the
magnet. When this contact is so made the Cu pole of the local cell is thus in
connection with the main framework. It will then be seen that when either
lever K is pressed into contact with piece P on pillar L. P. E or cam I on the main
arbor C comes into contact with spring N, lever K being still in contact with
piece L, the local current will go on vid lever K and terminal S₁ and T. C. to the
switch hook and switch bell and thence to the under stud of the switch hook (or
that stud with which the hook makes contact when the telephone is removed
therefrom, so that when this is the case the bell is short circuited). From here the
current goes on through the primary coil of the induction coil, and transmitter to
the zinc pole of the local cell.
It will thus be seen that when the local circuit is completed by the signal, and
the telephone is on the hook, the current passes through the bell, transmitter, and
primary in series; but since the resistances of the latter two are low, the bell rings
until the telephone is taken off the hook, when it is stopped by being short
circuited, and the current concentrated on to the transmitter and primary, the bell
being again unshort-circuited however, and therefore again commencing to sound,
when the telephone is hung up thus giving the subscriber an unmistakable
reminder to clear the line, should he tend to omit to do so.
Our line batteries are placed one at each end of the line, and opposed to each
other, so that, being equal, no current normally flows; but they are brought into
effective action by the plunger at any station, the effect of which is to put a
momentary intermediate earth on the line, the lower contact piece E on pillar L. P. E
(Figures 1 to 4) being connected to the earth terminal of the instrument for this
purpose.
The currents for propelling the step by step motion signals are then produced
automatically by the "actuator" (Figures 5 and 6) placed at one end of the line,
between Cu of the line battery and the signal instrument. This actuator consists
of an electro-magnet a, whose armature b carries the "sucker" c, made of soft india
rubber and the simple spring wire switch d. This switch wire rubs over the
compound pillar e. f made of two pieces of metal separated by an insulating
material; the piece f presenting its surface to the wire on the upper side of the
junction line g. h, and the piece e, on the lower side. Notches formed in the
respective pieces retain the wire until it is pushed by the upper or lower edge of
the slot formed in the plate i, also carried on the end of the arm b.
The sucker c. when it is pressed down by the armature, will adhere to its
plate k and take a certain definite interval of time to rise almost independent of
the strength of the upward pull. The connections of the actuator are then as
follows, zinc of the line battery being to earth, a lead is run from the Cu pole
thereof to the terminal marked Cu of the actuator, whence it goes on through the
coils of electro-magnet a. to the upper piece f of the compound piece f. e, with
which piece (f) the wire switch d. is normally in contact.
From here the current goes on through the switch wire d. and arm 6 to terminal
marked L and thence to the signal line." When the arm b is pulled down, however
by a momentary current from the home line battery going out to line, (caused by
the momentary intermediate earth put on by a calling subscriber) the switch
wire d at the latter end of the stroke, leaves f and makes contact with e. which is
connected through coils m. to terminal E which is earthed, thus insulating the
home line battery at point f and putting the line from the distant end to earth
through the ordinary vibrating bell actuator m, which has however, a heavier
pendulous rod in place of the hammer.
The current from the distant line battery, therefore, then runs through all the

page_text: signals on the line to earth through this vibrator, which imparts to it the proper
pulsations for working the signals. This condition remains while the sucker is
coming up. The duration of this period is arranged to be somewhat longer than
the signals require to make one complete revolution, so that once started and left
to themselves the signals would certainly come up to zero, from whatever position
they were originally in. The arrangement in the signal instruments themselves
then provides that they shall not run past zero.
This is accomplished as follows. There are two stops for limiting the length of
stroke of the signal armature during its backward motion, one being the stud R
(Figures 1 to 4), which limits its extreme backward position, and the other
consisting of a sucker similar to but smaller than that in the transmitter The
sucker Y is mounted on an arm projecting from the armature pivot M and working
on to a stationary plate. A pulling off spring is also provided as shewn.
The sucker begins to resist the further motion of the armature when it is half
way back, and causes it to take a certain interval of time (say 1 second) to perform
the other half. The first current which passes through the coils D draws the
armature right up, and unless there be a comparatively long interval of rest
between it and the next current, the armature will only get part of the way back,
and will therefore only be moved by the succeeding currents through a shorter
stroke.
The teeth in the ratchet wheel O on the arbor C are of such a size that the half
length strokes of the click rod on pivot M are sufficient to take them up, but, since
at the zero point in the wheel the space. between two teeth is left uncut, the short
inotions of the armature will not allow the click to drop over the uncut space, so
that the wheel cannot be turned past zero until a comparatively long interval of
rest (say 1 second) has been allowed between the currents to enable the click rod
to go right back to the stud R which is set to allow the click to just drop over the
uncut space.
If any of the instruments in circuit have dropped behind, they will
continue to advance until they come up to zero, the forward ones simply waiting
for them to come up.
The place of the ordinary locking click is taken in the signals by a piece of
spring wire X entirely avoiding the complications of adjustment of the relative
positions of two clicks, which would otherwise arise from the presence of the uncut
space in the wheel.
The action of the whole is then as follows:-The line being disengaged, and the
signals therefore pointing to zero, a subscriber calls by first removing his telephone,
and then pressing his plunger right down, the locking-lever H then allowing this
to take place in consequence of its being held over into its "unlocked" position by
the cam G. The effect of this motion is to put a momentary intermediate earth
on the line, and then immediately to remove it, the contact of lever K with
spring wire S, keeping the speaking instruments still short-circuited. The switch
b. d. in the actuator is therefore drawn down by the momentary current and the
battery at the other end then runs through all the signals on the line to earth,
through the vibrator as before explained-the pulsations. produced by the latter
causing the signals to isochronously advance step by step. Then when the hands
come to the number the caller wants, he releases his plunger, which however, does
not now come right up to its original position in consequence of lever H having
been let go.
The breaking of the contact of K with S suddenly removes the only remaining
short circuit of the callers speaking instruments, and throws their resistance (and
if desirable it may be supplemented by an addition resistance) into the line circuit,
thus weakening the pulsatory currents too much to further advance the signals,
although the currents are kept on a little longer by the actuator. The subsequent
clearing of the line is effected as described in our former Specification.
Having thus described the nature of our said Invention and the manner of
performing the same we would have it understood that we claim :—
First. The combination of the "actuator" with the signal instruments, batteries

page_text: and keys, the said keys starting the actuator and stopping signal instruments
substantially as described.
Second. The means substantially as described for synchronising step by step
instruments consisting in causing the first step of propeling pawl to be longer
than the succeeding steps to overstep a gap in the propelment ratchet.
Third. The means for retarding the return of the electro-magnet armatures of
telegraphic and telephonic apparatus by connecting the same with suckers or valves
substantially as herein described.
Fourth. Our improvements in telegraphic and telephonic apparatus substantially
as described.
In witness whereof I the said Alfred Charles Brown have hereunto set my
hand and seal this Sixteenth day of March in the year of our Lord One
thousand eight hundred and eighty three.
ALFRED CHAB. BROWN. (L.S.)