IMPROVEMENTS IN ELECTRIC SIGNALLING TELEGRAPHS AND VISUAL INDICATORS FOR USE THEREWITA
Year: 1880

page_text: LETTERS PATENT to William Clark, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN ELECTRIC
SIGNALLING TELEGRAPHS AND VISUAL INDICATORS FOR USE THEREWITA.”
A communication from abroad by John Van Dussen Reed, of the City, County,
and State of New York, United States of America.
PROVISIONAL SPECIFICATION left by the said William Clark at the Office
of the Commissioners of Patents on the 28th August 1880.
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. "IMPROVEMENTS IN ELECTRIC SIGNALLING TELEGRAPHS AND VISUAL
INDICATORS FOR USE THEREWITH." [A communication from abroad by John Van
Dussen Reed, of the City, County, and State of New York, United States of
America.]
This Invention relates partly to electric signalling telegraphs and partly to
indicators for use therewith, which point out or display one figure or other
character of a series, or one character of each of two or more series, and its object
is to produce a telegraph and indicator which can be operated with extreme
rapidity and which shall be accurate and reliable, displaying always at the
indicator the figure or character intended without confusing it with other
characters.
The Invention is particularly adapted to fire and burglar-alarm telegraphs, and
hotel annunciators, and to telephones, although applicable also to other forms of
electric signals.
In carrying out the Invention I arrange an electric circuit, which I will call the
line circuit, including a battery, one or more sending stations, and one or more
receiving stations. This circuit may be normally either open or closed, but I will
first describe it as open. I provide each sending station with mechanism for closing
and breaking this circuit a certain number of times in rapid succession whenever
it is operated to send a signal, and I provide each receiving station with the
indicator berein before referred to, which is controlled in its operation by the said
circuit, and which I arrange to advance one character for each closure and for each

page_text: break in the circuit instead of one for each closure only, as heretofore, whereby the
speed of transmission of the signal is doubled.
The visual indicator consists essentially of a number of figures or other
characters arranged in series, a non-intermittently-moving part (or one which
moves continuously from its starting to its stoppage), the extent of whose
movement determines which of said characters is exposed, and an electro-magnetic
stop-device which governs the extent of movement of said part, and is itself
operated by the closures and breaks of the circuit.
The first closure of the circuit releases the non-intermittently moving part, and
it commences its movement.
If the first character of the series is to be exposed the circuit remains open until
said part has traversed the required space, when it is intercepted and stopped by
the stop-device, but if some other character is to be exposed the circuit is broken
before the moving part has traversed said first space, and it may be afterward
again closed and broken any desired number of times, according to which character
of the series is to be displayed, the effect of which will be to permit the moving
part to traverse as many spaces as the total number of closures and breaks in the
circuit, and to display the corresponding character of the series. The characters
may be marked upon a stationary surface, and the moving part may carry either a
pointer to point out any one character or a screen which covers all the characters,
and has an opening through which but one at a time may be exposed, or the
characters may be marked upon the moving part and moved opposite a fixed
pointer or behind a fixed screen..
1
The preferred construction of the indicator is as follows :—
An electro-magnet is arranged in the circuit and its armature is mounted on a
lever, which is capable of vibration toward and from the magnet, and is normally
drawn away therefrom by a retracting force. The outer end of this lever forms or
bears a pallet for engagement with a series of escapement-teeth, which are formed
upon an escapement-rack, being arranged alternately upon opposite sides thereof
and pointing in opposite directions.
The escapement-rack is mounted in vertical guides, and tends always to descend
therein, being normally upheld by the pallet, which rests under its bottom tooth.
Its teeth are so proportioned to the pallet that the movement of the latter from
one side to the other releases a tooth on one side and engages the succeeding tooth
upon the opposite side, permitting the rack to fall a distance equal to that
between the two teeth, but no. further. Thus the descending movement of the
rack is intermittent, it dropping the distance from one tooth to the next at each
movement of the pallet.
To the escaperuent-rack, or to some part moved thereby, is fixed a tooth, pin,
spring-latch, or other stop,: which is caused to travel intermittently in a certain path.
The several characters of the series to be indicated are marked or applied at
suitable intervals to the surface of a non-intermittently moving part, before which
is placed a fixed screen arranged to conceal all but one of the characters, that one
being exposed through an opening in the screen. I prefer that a blank space be
arranged to stand opposite said opening when the apparatus is in its normal
position, so that until the indicator is operated no character is visible. The
non-intermittently moving part may be a slide or drop, but I prefer to employ a
wheel, disc, or cylinder, which, by the action of a weight or spring, tends constantly
to revolve upon its axis in one direction, but is normally held stationary. When
released it immediately commences its movement, which it continues without
interruption until it is stopped, and it is stopped only at such points in its course
as to bring one of its characters directly before the opening in the screen. This
non-intermittently-moving part or wheel has upon its surface a series of pins,
lugs, catches, or other provisions, which I will call stop-pins, which equal in
number the characters upon the wheel, and are arranged at angular intervals
corresponding to those between the characters. Each stop-pin is arranged to
travel when the wheel is in motion in a separate path, each of which paths crosses

page_text: the path of the intermittent stop at one of its stopping points. The path of the
first stop-pin, corresponding to the blank space on the wheel, crosses the path of
the intermittent stop at the normal or starting position of the latter and normally
rests against it, thereby keeping the wheel from revolving.
So far as described the operation is as follows:-
At starting the circuit is open, the armature retracted, the escapement rack
elevated and upheld by the pallet, the intermittent stop consequently at the
beginning of its travel, the first stop-pin resting against said stop, the wheel thereby
held stationary at the beginning of its travel, and its blank space exposed at the
screen-opening. Assuming that the fifth character of the series is to be displayed
the circuit is closed, broken, closed, broken, and closed in rapid succession, causing
the armature and pallet to perform five movements, at the first of which the pallet
passes from under the lowest escapement-tooth, permitting the rack to fall one
space, moving the intermittent stop one space, releasing the first stop-pin, and
permitting the wheel to commence its revolution. The intermittent stop is then
in the path of the approaching second stop-pin, but before that reaches it the second
movement is made, the rack and stop move a second space, and in quick succession
thereafter the remaining three movements are made, bringing the stop to the end
of its fifth movement, and in the path of the sixth stop-pin, which it intercepts, and
thereby stops the wheel after the latter has moved four characters past the screen-
opening, and while its fifth character is directly behind said opening. The
first four characters pass the opening so rapidly that they are illegible, whereby
misreading of the indicator is prevented.
To prevent a rebound of the wheel when it is thus suddenly stopped, I provide
a latch which is operated by the engagement of the stop-pin with the intermittent
stop. If the stop is itself a spring-catch no extraneous device will be necessary,
but I prefer to provide a spring-lever capable of engaging any of a series of
catch-pins or other provisions on the wheel, which correspond in number and
spacings to the characters and stop-pins, and with one of which it is moved into
engagement by a lateral movement on the part bearing the intermittent stop when
that stop is struck by the stop-pin, at which time one of the catch-pins is directly
opposite to its engaging socket or portion.
The mechanism thus far described is capable of indicating but one character at a
time. When it is required to indicate two or more characters simultaneously, as in
signalling numbers of two or more figures, the above described apparatus, which I
will call au indicating system, is duplicated or further multiplied, and the several
systems are operated successively, each being in a separate branch of the circuit, and
a switch being connected with each system except the last to shunt its own branch
out of circuit, and the branch of the succeeding system into circuit, when its own
operation is completed. This switch is operated by the forcible contact of the stop-
pin with the intermittent stop which forces the part bearing the stop to one side,
and this movement is communicated to a switch-lever which moves off from one
anvil or contact-point on to another anvil or contact point, thus switching the
circuit to the branch of the succeeding system. The subsequent closures and breaks
of circuit will then affect the latter system instead of the former.
To restore the several parts to their original positions after the operation is
completed, in order that another signal may be received, I provide a resetting
device, which may consist of a cord to rotate the wheel backward to its starting
point, and a sliding frame bearing a spring to press the escapement-rack into
up
place, a wedge cam to force the wheel-latch out of engagement with the wheel, and
a shoulder to restore the switch, the cord and frame both deriving motion from
cams or other provisions on a crank shaft.
In lieu of arranging a series of stop-pins to move across the path of the inter
mittent stop the wheel or other non-intermittently moving part may have but one
pin, and that may move in the same path as the stop, but must move somewhat
slower, being started when the stop moves away from it, and following the latter
until stopped by the final stoppage thereof.

page_text: I will now'describe another form of my indicator which presents some structural
..differences from the one already described.
The non-intermittently moving part is in the form of a drop-slide tending always
"to fall, but normally upheld, and the electric stop device is in the form of a series
of detents instead of an escapement. These detents correspond in number and
spacing with the characters on the slide, are arranged one below another in
proximity thereto, and are adapted to engage a shoulder thereon, which shoulder
may be its bottom edge, or some projection from its back or elsewhere. Each
detent is operated by a separate electro-magnet, which I will call the detent
magnet.
A double-acting relay is placed in the line circuit, and its lever controls two
local circuits, or, preferably, two branches of one local circuit, which .I will call
primary branches. These it closes alternately, so that each branch is always broken
while the other is closed. Each primary branch is again divided into several
secondary branches, corresponding in number to the detents, and in each of these
secondary branches is placed one of the detent-magnets.
The alternate detent-magnets are placed in the secondary branches of one
primary branch, and the intermediate ones are placed in those of the other primary
branch. Each detent-magnet is connected with a switch, which it operates when
it becomes charged, and the operation of which acts to switch its own secondary
branch out of, and that of the detent below into, circuit with the local battery.
The upper detent normally upholds the drop, and its magnet is in a secondary
branch of the primary branch which is normally broken at the relay, the succeeding
detent-magnet being in a secondary branch of the primary branch, which is
normally closed at the relay, but which, like each succeeding branch, is broken at
the switch which is operated by the preceding detent-magnet.
Thus normally the local battery is inactive, all the branches of its circuit being
broken. When the relay first moves it establishes the circuit through the first
detent-magnet, withdrawing that detent and releasing the drop which commences
its descent, and simultaneously switching the branch of the detent magnet below
into circuit, but as this branch is then broken at the relay the magnet does not
become charged. The other detents stand normally in the path of the drop, being
withdrawn therefrom when their magnets become charged, so that the distance
through which the drop will fall depends upon the number of detents drawn
back, it being stopped by the highest detent which is not retracted. If the drop
is to show other than its first character the second detent must be withdrawn
before the drop encounters it, this being caused by the return movement of the
relay-lever. For each movement of the relay-lever one detent is withdrawn, so
that the character to be displayed by the drop will depend upon the number of
movements of the relay, and that upon the number of breaks and closures in the
line circuit.
The apparatus just described constitutes one indicating system. If it is desired
to operate two or more such systems successively each system will be arranged
in separate branches of the local circuit, and each, except the last, will be provided
with a system switch to be operated by the forcible contact of the drop with
the arresting detent, and by its operation to shunt itself out of, and the succeeding
system into, circuit with the local battery and the relay, so that the subsequent
operation of the relay will affect the latter system instead the former.
To reset the apparatus the drop is raised until the upper detent sustains it, and
the several switches and detents are returned to their original positions.
With either form of indicator when two or more indicating systems are arranged
for successive operation, if the operation of one ceases while the actuating circuit
is in the condition (either open or closed) pre-arranged to effect the first action of
the next system, the act of switching the circuit to said system will excite its magnet
(or its first magnet), and it will display its first character and switch the circuit to
the third, thus causing the indication of a different set of characters from that
intended and causing confusion.

page_text: To correct this erroneous tendency I interpose what I term a correcting switch
between each two systems, and arrange the switch of the first system to shunt the.
circuit to the correcting switch, and the latter to control the shunting of the
circuit to the second system. When the first system switch shunts to the correcting
switch while the actuating circuit is in opposite condition from that pre-arranged
to effect the starting of the second system, the correcting switch acts and shunts
the second system into circuit, but if the circuit be in the condition pre-arranged to
start the second system, the correcting switch witholds the circuit therefrom until
the circuit returns to the opposite condition, when it acts and shunts the circuit to
the second system correctly. The correcting switch is operated by an electro
magnet which is arranged in the actuating circuit, or a branch thereof, or in a
circuit operated therefrom by a relay.
The transmitting instrument is of nearly the same construction, whether the
circuit be normally open or closed, and consists, essentially, of a key for breaking
or closing the circuit vibrated by the automatic mechanisın. The preferable
mechanism for this purpose consists of a cam wheel having teeth to raise and drop
the key. The cam wheel is rotated by clock-work, which is normally restrained
by a catch, and a pull-lever is provided, the pulley of which winds up the clock work
and then withdraws the catch, which permits the rotation of the wheel until the
latter has completed one revolution or other predetermined movement, when it
intercepts and stops.
The cam wheel of each signalling mechanism will usually be cut to transmit a
different character, or group of characters, to be exposed at the indicator from that
or those transmitted by the wheels of the other mechanisms, so that the indicated
character will show which transmitting mechanism has been operated. Both sides
of each tooth are of effect in determining the character transmitted, instead of one
tooth being used for each character as heretofore. Thus a given signal may be
transmitted at relatively double the speed heretofore attained.
The transmitter may be set to transmit any desired number instead of always
transmitting the same number, and to this end I employ drop slides, each controlling
one indicating system at the receiving station, and each having enough cam teeth
to cause the key to leave and touch its contact point, say, 10 times to transmit the
number 9, and to cause any lower number to be transmitted a pin is placed in a
hole in the slide, which is marked with the number desired. The slide is started
by pulling out a pin below it, and it descends until the first pin strikes the frame
below and stops it. This pin thus forms an adjustable stop to limit the movement
of the slide to any desired extent, according to which hole it is placed in, and thus
to determine the number of cam teeth which shall act upon the key.
In addition to the uses herein before referred to, the Invention is also applicable
to telephone central offices, where a number of telephone circuits converge, to
enable an operator on one circuit to announce the number of another circuit with
which he wishes to be connected. Each such circuit includes a magnet at the
central office, whose operation drops a shutter or screen and exposes the number of
the circuit; it will also be in connection with a relay which will control the
indicator circuit. Each operator will be provided with a transmitting device, with
which he can transmit any desired number instead of but one number, and having,
by it, transmitted the number of the circuit with which he wishes to be connected,
that number will be displayed by the indicator at the central office almost
simultaneously with the exposure of the number of his own circuit.
The attendant at the central office will thus know that he is to connect together,
or throw into one circuit, the two circuits whose numbers are displayed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Clark in the Great Seal Patent Office on the 28th February
1881.
"
WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex, Patent
Agent. IMPROVEMENTS IN ELECTRIC SIGNALLING TELEGRAPHS AND VISUAL
INDICATORS FOR USE THEREWITH." A communication from abroad by John Van
Dussen Reed, of the City, County, and State of New York, United States of
America.
This Invention relates partly to electric signalling telegraphs and partly to
indicators for use therewith, which point out or display one figure or other
character of a series, or one character of each of two or more series, and its object
is to produce a telegraph and indicator which can be operated with extreme
rapidity, and which shall be accurate and reliable, displaying always at the indicator
the figure or character intended without confusing it with other characters.
The Invention is particularly adapted to fire and burglar aların telegraphs and
hotel annunciators, although applicable also to other forms of electric signals.
In carrying out the Invention I arrange an electric circuit A, shown in the
diagram, Figure 1, of the Drawings, which I will call the line circuit, including a
battery, one or more sending stations B, B, and one or more receiving stations C.
This circuit may be normally either open or closed, but I will first describe it as
open, as shown in said Figure. I provide each sending station B with mechanism
for closing and breaking this circuit a certain number of times in rapid succession
whenever it is operated to send a signal, and I provide each receiving station C
with the indicator herein before referred to, which is controlled in its operation by
the circuit A, and which I arrange to advance one character for each closure and
for each break in the circuit A, instead of one for each closure only as heretofore,
whereby the speed of transmission of the signal is doubled.
The visual indicator consists essentially of a number of figures or other characters
arranged in series, a non-intermittently moving part (or one which moves
continuously from its starting to its stoppage), the extent of whose movement
determines which of said characters is displayed, and an electro-magnetic stop
. device which governs the extent of movement of said part, and is itself operated
by the closures and breaks of the circuit. The circuit being normally open, the
first closure releases the non-intermittently moving part, and it commences its
movement. If the first character of the series is to be exposed the circuit remains
open until said part has traversed the required space, when it is intercepted and
stopped by the stop device, but if some other character is to be exposed the circuit
is broken before the moving part has traversed said first space, and it may be
afterward again closed and broken any desired number of times, according to
which character of the series is to be displayed, the effect of which will be to permit
the moving part to traverse as many spaces as the total number of closures and
breaks, and to display the corresponding character of the series. The characters
may be marked upon a stationary surface, and the moving part may carry either a
pointer to point out any one character, or a screen which covers all the characters
and has an opening through which but one at a time may be exposed; or the
characters may be marked upon the moving part and be moved opposite a fixed
pointer, or behind a fixed screen.
The preferred construction of the indicator is illustrated in Figures 2 to 5
inclusive, the particular construction shown being designed to display any one of
ten figures or other characters. Figure 2 is a side elevation partly in section on
the dotted line 8-s, Figure 3; Figure 3 is a front elevation; Figure 4 is a plan
partly in horizontal section on the line t-t, Figure 2; and Figure 5 is a front
elevation in section on the line u-u, Figure 2.

page_text: Referring to these Figures, D is an electro-magnet arranged in the circuit A
(Fig. 1) with its armature mounted on a lever a, which is capable of vibration
toward and from the magnet, and is nominally drawn away therefrom by a
The outer end of the lever a forms or bears a
retracting spring a¹ or other force.
pallet for engagement with a series of escapement teeth c, c, which are formed
upon an escapement rack d, being arranged alternately upon opposite sides thereof
and pointing in opposite directions. The rack d is mounted in vertical guides and
tends always to descend therein, being normally upheld by the pallet which rests
under its bottom tooth. Its teeth are so proportioned to the pallet that the
movement of the latter from one side to the other releases a tooth on one side and
engages the succeeding tooth upon the opposite side, permitting the rack to fall a
distance equal to that between the two teeth, but no further. Thus the descending
movement of the rack is intermittent, it dropping the distance from one tooth to the
next at each movement of the pallet.
To the escapement rack, or to some part moved thereby, is fixed a tooth, pin,
spring latch, or other stop E, which is caused to travel intermittently in a certain
path.
The several characters of the series to be indicated, are marked or applied at
suitable intervals to the surface of a non-intermittently moving part F, before
which is placed a fixed screen (letter G, and shown in Fig. 7), arranged to
conceal all but one of the characters, that one being exposed through an opening e
in the screen. I prefer that a blank space be arranged to stand opposite said
opening e when the apparatus is in its normal position, so that until the indicator
is operated no character is visible. The part F may be a slide or drop, but I
prefer to employ a wheel, disc, or cylinder, as shown, which by the action of a
weight or spring tends constantly to revolve upon its axis in the direction of the
arrow in Figure 2, but is normally held stationary. When released it immediately
commences its movement, which it continues without interruption until it is stopped,
and it is stopped only at such points of its course as to bring one of its characters
directly before the opening e in the screen. This non-intermittently moving part
or wheel has upon its surface a series of pins, lugs, catches, or other stops f, f
(which I will call stop-pins), and which equal in number the characters upon the
wheel, and are arranged at angular intervals corresponding to those between the
characters. Each stop pin f is arranged to travel when the wheel is in motion in
a separate path, each of which paths crosses the path of the intermittent stop E at
one of its stopping points. The path of the first stop pin f (corresponding to the
blank space on the wheel) crosses the path of the stop E at the normal or starting
position of the latter and normally rests against it, thereby keeping the wheel F
from revolving.
So far as described the operation is as follows :—
At starting the circuit A is open, the armature retracted, the escapement rack d
elevated and upheld by the pallet which rests under its lowest tooth c,
the intermittent stop E consequently also at the beginning of its travel, the first
stop pin f resting against said stop, the wheel F thereby held stationary at the
beginning of its travel, and its blank space exposed at the screen opening e.
Assuming that the fifth character of the series is to be displayed (being the number
"4" in the Drawings) the circuit is closed, broken, closed, broken, and closed in
rapid succession, causing the armature and pallet to perform 5 movements, at the
first of which the pallet passes from under the lowest escapement tooth, permitting
the rack d to fall one space, moving the intermittent stop E one space, releasing the
first stop pin f of the wheel F and permitting the wheel to commence its revolution.
The intermittent stop is then in the path of the approaching second stop pin f
(marked o in Figure 2), but before that reaches it the second movement is made,
the rack and the intermittent stop move a second space, and in quick succession
thereafter the remaining three movements are made, bringing the stop E to the end
of its fifth movement and in the path of the sixth stop-pin f (marked "4"), which
it intercepts and thereby stops the wheel after the latter has moved four characters

page_text: past the screen opening e, and while its fifth character (the Figure "4") is directly
behind said opening. The first four characters pass the opening e so rapidly that
they are illegible or indistinguishable, whereby misreading of the indicator is
prevented.
To prevent a rebound of the wheel F when it is thus suddenly stopped I provide
a locking device which is operated by the engagement of the stop pin f with the
stop E. If the latter is itself a spring catch no additional device will be necessary,
but I prefer to provide a spring lever g capable of engaging any of a series of catch
pins or other provisions g' on the wheel F, which catch pins correspond in
number and spacing to the characters and stop pins. The spring lever g is moved
into engagement with one of the pins g' by a lateral movement of the part bearing
the intermittent stop when that stop is struck by one of the stop pins f, at which
time one of the catch pins g¹ is directly opposite to the engaging socket or portion
of the lever g. The lateral movement of the stop E is cominunicated to the lever g
through a sliding rod which extends from the part bearing the stop to the upper
arm of the lever g. The latter is kept from returning to its original position
and thereby releasing the catch pin by a drop lever h which falls down in front
of it.
Figure 6 is a detached plan showing a modified arrangement of the magnet D.
A second magnet is placed opposite the first in place of the spring a¹, and the two
magnets are arranged in separate branches of a local circuit A' which is controlled
by a double acting relay H in the line circuit A. This relay as it vibrates
alternately closes the branches of the local circuit, whereby the magnets are
alternately charged and alternately attract the armature lever a.
The mechanism thus far described is capable of indicating but one character at
a time. When it is required to indicate two or more characters, as in signalling
numbers of two or more figures, the above described apparatus, which I will call
an indicating system, is duplicated or further multiplied, and the several systems
are operated successively, each being in a separate branch of the circuit, and a
switch I being connected with each system except the last to shunt its own branch
out of circuit, and the branch of the succeeding system into circuit when its own
operation is completed. This switch is operated by the forcible contact of the stop
pin f with the stop E, which forces the part bearing the latter to one side, and
this movement is communicated through the rod h¹ to the lever g, whose end
normally upholds the switch lever h, forcing it from under the latter, which then
drops off from one anvil or contact point i, thus cutting the branch of its own
system out of circuit, onto another anvil or contact point ', which re-establishes
the circuit through the branch of the succeeding system. The manipulation of the
circuit A at the sending station is suspended for a short interval to give time for
this operation to take place, and when it is resumed it affects the second system
instead of the first.
Figs. 7 and 8 illustrate two indicating systems enclosed in a case arranged to
operate successively, and provided with all the necessary accessories for practical
operation, Figure 7 being a side elevation in vertical section on the line v-, in
Figure 8, and Figure 8 being a front elevation, the left half in section on the line
ww, in Figure 7, with the left wheel F removed, and the right half in section
on the line x-x, in Fig. 7.
Fig. 9 is a diagram of the circuit connections for the form of apparatus shown in
Figs. 7 and 8.
With two or more indicating systems arranged as described for successive
operation in case the operation of the first ceases while the circuit is in the
condition (either broken or closed) prearranged to effect the first action of the
second system, the act of shunting the circuit thereto by the switch I will excite
its magnet D and it will display its first character, and its switch I will shunt it
out of circuit, thus effecting the exhibition of a different set of characters from
that intended and thereby causing confusion. To correct this erroneous tendency
I interpose what I term a "correcting switch," shown at J. in Figures 7, 8, and 9,

page_text: between each two systems, and arrange the system switch I of the first system to
shunt the circuit to the correcting switch, and the latter to control the shunting
of the circuit to the second system. The correcting switch is operated by an
electro-magnet J'. The preferable arrangement of circuits is shown in Fig. 9,
wherein A is a local circuit divided into two branches j, j¹, which are closed
alternately by the double acting relay H whose magnet is in the main circuit A.
Normally the magnet D of the first system is in the branch j which is broken at
the relay, and the magnet J¹ is in the branch' which is broken at the point
of the first switch I. The magnet D of the second system is cut out of the
branch at the point of the correcting switch, which switch consists of a spring k
The
norinally upheld against the point by the armature of the magnet J
closures of the branch j operate the first indicating system until its switch I drops,
when its magnet D is switched out of the branch and the circuit j¹ is closed at i'.
If the operation of the first system ceases with the branch j closed, the branch j¹
is broken at the relay and will not operate the correcting switch until the relay
closes it, but if the operation ceases with the branch j open, the branch j¹ is closed
and the magnet J¹ attracts its armature, which releases the spring k, which falls
onto the point ", which switches the magnet D of the second system into the
branch, which branch is then broken at the relay. The first closure of that
branch at the relay then commences the operation of the second system.
After the operation of the indicator is completed the several parts must be
restored to their original positions in order that another signal may be received.
I provide for this purpose a re-setting device, which is shown in Figures 7 and 8,
and consists of cords m, m, to rotate the wheels F, F, back to place, and sliding
rods L, L, each provided with a cam n to disengage the wheel latch g, a spring
to press up the rack d, a shoulder n to lift the switch lever into place, a'id
another shoulder 111 (which I have shown as its upper end) to lift the spring k of
the correcting switch. The cords m, m, and rods L, L, all derive motion from a
crank shaft L' as shown.
1
The circuit A in Figure 9 is shown as normally closed, being broken at either of
the sending stations B, B, to send a signal. The signalling apparatus shown
consists of a spring key working against a contact point 1, and forced away
therefrom by teeth on a revolving cam wheel K; this is shown on a larger scale in
Figure 10. One revolution of the wheel in the direction of the arrow suffices to
cause the number which it is formed to transmit to be exposed at the indicator.
Each wheel is formed to transmit a different number, those shown in Figures 9, 10,
and 13 being designed to transmit numbers of two figures, as marked thereon.
Each side of each tooth corresponds to one of the characters at the indicator, as
shown by the small figures marked opposite them, the teeth in the first series p
actuating the first indicating system, the following space p¹ giving time for the
switch I of that system to operate, and the second series p₁₁ actuating the second
system. The abrupt side of the tooth q closes the line circuit to operate the
correcting switch.
Figures 11 and 12 show the mechanism for operating the cam wheel, each being
a vertical section taken on the line x-x in the other. A clock work is driven by a
weight or spring, and is normally held stationary by a spring catch q' which
engages a pin or projection on one of the wheels. The pulling of the pull lever r
first winds up the weight by means of the cord connected to it, and then presses
back the catch q¹ by the contact of the abutting toes, ¹, which releases the
clockwork and permits it to revolve the wheel K once or other predetermined
number of times, when the catch q¹ again engages the clockwork and stops it.
Figures 14 to 19 represent another form of indicator, which differs in some
respects from the one already described; Figure 14 is a diagram showing the
relative arrangement of circuits and other parts; Figure 15 is a front elevation of
an indicator, having three indicating systems arranged in a case; Figs. 16, 17,
18, and 19 are views of the mechanisin upon a larger scale, each indicating system
having but four characters in its series, Figures 16 and 17 being vertical cross

page_text: sections taken respectively on the lines y-y and z-z, and Figures 18 and 19 being
respectively front and rear elevations.
Referring to these Figures, the non-intermittently moving part is in the form
of a drop slide F tending always to fall but normally upheld, and the electric stop
device is in the form of a series of detents E, E, instead of an escapement and
intermittent stop. These detents correspond in number and spacing with the
characters on the slide, are arranged one below another in proximity thereto, and
are adapted to engage a shoulder thereon, which shoulder may be its bottom edge
or some projection from its back or elsewhere. Each detent E is operated by a
separate electro magnet D, which I will call the detent magnet.
As shown in Figure 14, a double acting relay H is placed in the line circuit, and
its lever controls two branches ; and j' of one local circuit, which I will call
primary branches. These it closes alternately, so that each branch is always broken
while the other is closed. The branch jis subdivided into several secondary
branches o, and the branch j' into secondary branches o'. These branches o and o'
correspond in number to the detents E, E, and in each is placed one of the detent
magnets D, the alternate magnets being placed in the branches o, o, and the inter-
mmediate ones in the branches o', o¹. The armature of each detent magnet is
arranged to operate a switch M. as the magnet. becomes charged, and thereby to
switch its own secondary branch o or o¹ out of, and that of the magnet below into,
electrical connection with the local battery and the relay. The upper detent
normally upholds the drop, and its magnet is in a secondary branch o, whose
primary branch j is normally broken at the relay, the succeeding detent magnet
being in a secondary branch o¹, which, like each succeeding secondary branch, is
broken at one of the switches M. Thus normally the local battery is inactive, all
the branches of its circuit being broken. When the relay first moves it closes the
circuit through the branch j and the upper magnet D, causing that magnet to
withdraw its detent E and release the drop F, which commences its descent.
also operates the switch M, which breaks its circuit and switches the branch o' of
the second detent magnet into circuit, but as the branch j¹ is then broken at the
relay that magnet does not become charged. The other detents E, E, stand
normally in the path of the shoulder F, being withdrawn therefrom when their
magnets become charged, so that the distance through which the drop will fall
depends upon the number of detents drawn back, it being stopped by the highest
detent which is not retracted. If the drop is to show other than its first character
(the figure "0" in the Drawings) the second detent must be withdrawn before the
drop encounters it, this being caused by the return movement of the relay lever.
For each movement of the relay lever one detent is withdrawn, so that the
character to be displayed by the drop will depend upon the number of movements
of the relay, and that upon the number of breaks and closures in the line circuit.
It
Each detent except the upper one consists of a horizontal rod N, which connects
with the switch M at one end and the armature of the magnet D at the other, the
latter end being adapted to engage the shoulder f on the drop, and passing through
a vertical bar h' which is capable of a slight vertical movement, and is connected
with the lever / of the system switch I. When the shoulder f strikes the rod N
it depresses it and draws down the bar h', which draws the lever or spring h down
from the contact point i onto the point i, as shown in Figure 16, thus switching
this indicating system out of the circuit and shunting the latter to the correcting
switch J which controls the shunting of the circuit to the next system, as before
described.
The above described construction is that employed when two or more systems
are used together. When but one is used the bar h¹ and switch I may be omitted.
In Figures 16, 17, and 19, is shown the preferred construction of the switches M.
The rod N connects with a spring P which presses toward the magnet D, and
whose free upper end normally rests under the switch spring Q (which presses
downward) and holds the latter up against its upper contact point. When the
magnet D attracts the armature, the latter presses back the rod N, which forces the

page_text: spring P out from under the spring Q and releases the latter, causing it to drop
from its upper onto its lower contact point.
To restore the apparatus after operation, I provide a sliding set rack R shown
in Figure 19, whose toes when it is lifted press up the springs Q, Q, and permit
the springs 'P, P, to pass under them again, at the same time forcing the rods N, N,
forward.
In addition to the uses hereinbefore referred to, the Invention is also applicable
to telephone central offices where a number of telephone circuits converge, to
enable an operator on one circuit to announce the number of another circuit with
which he wishes to be connected.
And having now described the nature of the said Invention and in what manner.
the same is to be performed, I declare that I claim,--
1. Operating an electric signalling telegraph whose receiving station is provided
with a visual indicator which is adapted to display the character of a series; that
corresponds to the total number of circuit breaks and circuit closures affecting it,
by alternately breaking and closing the circuit at the sending station as many
times as will correspond to the relative arrangement of the desired character in the
series at the indicator, and leaving the circuit in that condition (either broken or
closed) a sufficient time for the indicator to operate and display that character,
substantially as and in the manner described.
2. The improved visual indicator herein before described which is adapted to
display one character of a series, and to shift from the arrangement or position of
parts which will display one character to that which will display the succeeding
character of the series at each break or closure in its actuating circuit.
3. The improved visual indicator hereinbefore described, which is operated by
the brakes and closures of an electric circuit, and adapted to display one character
of a series through an opening in a screen, and which when operated to display a
character moves the preceding character of a series past the opening with such
rapidity, that they are illegible or undistinguishable and stops with the required
character opposite the opening.
4. In a visual-indicator, the combination with an electro-magnetic stop-device of
a non-intermittently moving part, whose movement is controlled by the stop-
device, and the extent of whose movement determines which character of a series is
displayed, substantially as set forth.
5. An electro-visual indicator, consisting of an intermittently moving part whose
movement is controlled by an electro-magnetic escapement, in combination with a
non-intermittently moving part, the extent of whose movement is determined by
the number of movements of the intermittent part and which determines which
character of a series is displayed, as set forth.
6. In an indicator, the combination of an intermittent stop E, the number of
whose progressive movements depends upon the number of movements of the
armature of an electro-magnet D, with a non-intermittently-moving part F adapted.
to be started by the action of the stop E, and to be stopped thereby at any one of
a series of points, and the extent of whose movement determines which character
of a series is displayed, substantially as herein before described.
7. In an indicator, the combination of an intermittent-stop E, whose movement
is controlled by an electro-magnetic escapement, with a non-intermittently moving
part F, provided with a series of stop-pins f, f, arranged successively in advance of
one another and each moving in a different path, the paths each crossing the path
of the intermittent stop at one of its stopping points, as set forth.
8. In an indicator, the means herein before described, for stopping and holding
the part bearing the characters after it has completed its operation, substantially as
set forth.
9. An electric-signalling telegraph, consisting of a line circuit A including one or
more sending stations B and the magnet of a double acting relay H, and a local
circuit A¹ divided into two branches and ¹, which the relay closes alternately and

page_text: which operate an electro-visual indicator, substantially in the manner hereinbefore
set forth.
10. In a visual indicator, a non-intermittently moving drop or other part F,
provided with a series of detents E, E, which normally rest in the path of its
movement, with electro-magnetic mechanism for retracting any required number of
detents from its path so as to determine the distance through which it shall move,
substantially as shown in Figures 14 to 19, and as set forth.
11. The combination with two indicator or indicating systems, such as
herein before described, the first of which is normally in operative connection with
the actuating circuit, with means for transferring this operative connection from
the first system to the second upon the completion of the operation of the first
system, substantially as set forth.
12. The combination with two indicating systems, each adapted to advance from
one character of a series to the next at each closure or break in the circuit, and
with means for shunting the circuit to the second when the operation of the first
system is completed, of a correcting switch to control the shunting of the circuit to
the second system, arranged to operate substantially as described.
In witness whereof, I, the said William Clark, have hereunto set my hand
and seal, this Twenty fifth day of February, in the year of our Lord 1881.
W CLARK. (L.S.)