APPARATUS." IMPROVEMENTS IN TELEPHONIC AND TELEGRAPHIC SIGNALLING Saunders
Year: 1881

page_text: LETTERS PATENT to Alfred Charles Brown and Henry Alfred Charles
Saunders, both of ou, Old Broad Street, in the City of London, for an
LETTERS PATENT to Alfred Charles Brown and Henry Alfred Charles
Saunders, both of ou, Old Broad Street, in the City of London, for an
Invention of
APPARATUS."
IMPROVEMENTS IN TELEPHONIC AND TELEGRAPHIC SIGNALLING
Saunders, DOCIE OI 00, Uid Broad Street, i11 the City of London, for an
Invention of IMPROVEMENTS IN TELEPHONIC AND TELEGRAPHIC SIGNALLING
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 7th July 1881.
ALFRED CHARLES BROWN and HENRY ALFRED CHARLES SAUNDERS, both of 66,
Old Broad Street, in the City of London. "IMPROVEMENTS IN TELEPHONIC AND
TELEGRAPHIC SIGNALLING APPARATUS."
The object of our Invention is to facilitate the intercommunication between
several telephone or telegraph stations on one and the same wire. For this
purpose we employ apparatus so arranged that not only can any station call up
and be placed in direct communication with any other station on the same wire
without having to go through a central office, but also so that none of the other
stations can interrupt or hear what is passing between the two stations occupying
the wire, and when telephonic apparatus is used so that upon cessation of com-
munication upon the caller replacing the telephone upon the switch hook, upon
which the telephone is ordinarily suspended whilst out of use, his bell will continue
to ring until he clears the line by bringing all the instruments back to their normal
position; and also so that all the stations in circuit can see that the line is
engaged, and also which station has been called up.
In carrying out this Invention we employ at each station an instrument having
a dial, upon which is marked numbers or signals corresponding with the number
of stations to be in circuit upon the wire. The stations are indicated by a hand
or pointer, which is made to revolve either by clock work or by a step by step
movement actuated by electric currents.
By a suitable arrangement of locking plates, cams, and spring contacts, and a
detent actuated by an electro magnet the signal apparatus at all of the stations

page_text: on the line can be started and stopped from any one or other station, and then all
the stations except the calling station and the station denoted by the number or
signal opposite to which the hands or pointers of all the several instruments is
stopped are so blocked or out of circuit that it is impossible for them to interrupt,
and they cannot communicate with any station on the wire until the several
apparatus have all been put back to their normal positions.
To control the starting and stopping of the apparatus we use a locking plate
or star wheel having as many slots or teeth as there are to be stations on the line,
and we lock or unlock by means of a detent actuated by an arm on the armature
of the electro magnet. The electro magnet used for actuating the detent may be
excited either by the line current or by a local current controlled by a relay.
When the apparatus at each station is at rest in its normal position, any station
can start the whole of the instruments by pressing his ringing key spring, which
when the instrument is in its normal position is free to pass through a slot in a
compound dise on the same arbor as the locking plates, and then to make or break
the necessary contacts for setting the hands or pointers of the several instruments
into movement.
.
In any other position during the revolution of the disc the spring is prevented
from making the necessary contacts by being stopped by the disc itself. When
after having passed through the slot the spring is released, it makes contact with
the back of the disc, and so brings into circuit the telephone and its secondary
connection. It also is so arranged by another spring contact that when the
telephone is replaced on its switch hook that the local circuit is completed through
the home bell, which continues to ring until the caller clears the line by again
pressing ringing key and allowing the apparatus to return to zero.
The arrangement of the apparatus is such that in the apparatus at the station
that has been called a cam on the same arbor as the locking plate and slotted disc
comes against and lifts two springs, breaking contact by the lifting of one spring
with earth or continuing line, and by the lifting of the other spring completing the
local circuit through the bell, and inserting the telephone and its secondary con-
nections in the line circuit. The cams are so placed in each instrument as to
affect this only when the hand or pointer of the instrument at any station is
brought to rest opposite to the number or signal that represents that station.

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 7th January 1882.
ALFRED CHARLES BROWN and HENRY ALFRED CHARLES SAUNDERS, both of 66,
Old Broad Street, in the City of London. "IMPROVEMENTS IN TELEPHONIC AND
TELEGRAPHIC SIGNALLING APPARATUS."
The object of our Invention is to facilitate the intercommunication between
several telephone or telegraph stations on one and the same wire.
For this purpose we employ apparatus so arranged that not only can any station
call up and place itself in direct communication with any other station on the
same wire without having to go through a central office, but also so that none of
the other stations can interrupt or hear what is passing between the two stations
occupying the wire.
And when telephonic apparatus is used we so arrange the apparatus that upon
the caller replacing the telephone upon the switch-hook upon which the telephone
is ordinarily suspended whilst out of use, his bell will commence to ring and
continue ringing until he clears the line, by bringing all the instruments back to
their normal position; and also so that all the stations in circuit can see that the
line is engaged and also which station has been called up.
We accomplish the above objects in the following manner:-
Each subscriber has a set of instruments similar to those shewn in Figures 1, 2,
3, 4, 5, and 6, in which Figure 1 is a front elevation of the call instrument or
signal, including the locking mechanism for shutting out all stations except the
caller and called stations and preventing them from tapping; Figure 2 is a side
elevation of the same call instrument or signal.
Both of these Figures are shewn with the cover carrying ringing buttons and
dial removed, but with their positions indicated by dotted lines. Figure 3 is a
front elevation of the switch bell transmitter which we use with the call instru-
ment, with the door open to show the inside; Figure 4 is a detail Drawing of the
slotted disc used together with the ringing spring movement; and Figure 5 is a
diagram of another form, which may be used instead of the slotted disc with its
accompanying mechanism.
The apparatus may be thus described, similar lettering being used throughout.
In Figure 1, A is a base board on which is mounted a clock frame B, carrying
a coiled spring and train of wheels which actuate a main arbor or axle C. The
clock work is controlled by an electro-magnet D, having a pivoted armature drawn
off the magnet by an adjustable spring b, and to which is attached a pallet working
into and controlling a scape wheel or arm E mounted on an arbor carrying a
pinion, which gears into a wheel on the main arbor C, the wheel and pinion being
properly proportioned according to the number of stations the instruments are to
control, giving a different position of the arbor for each station. The scape wheel
may be on the arbor C, but it is more convenient to have it on a separate axis
geared as described. In the Drawing a scape wheel with two arms or teeth is
indicated.
Or we can use instead of the above arrangement a step by step motion actuated
directly by the armature of the electro-magnet without the aid of clock work, and
turning the main arbor C either directly or through the medium of gearing, the
essential feature being simply that the arbor C shall be turned according to some
fixed ratio of the number of attractions and cessations, or reductions of attraction
of the electro-magnet D on its armature, or of reversals of polarity; if a polarised
arrangement be used we can use any arrangement which shall do this. The

page_text: electro magnet D may be excited either by the line current direct, or by a local
current controlled by a relay in the line circuit.
The main arbor C carries a hand or pointer F to indicate the numbers or signals
of the respective stations on the dial G; also a compound slotted disc or locking
plate H, and a cam I.
K is a ringing key consisting of a spring which is attached in any suitable way
to the main frame work, but electrically insulated therefrom; it is capable of being
pressed by a plunger & which projects through the case, as indicated in the
Drawing; L is a cross spring nominally bearing on and making contact with the
end of the ringing spring K, and also electrically insulated from the main frame
work. The above mentioned two springs' with the disc H can be seen more clearly
in the detail view Figure 4.
The compound slotted, disc H is composed of two pieces of metal electrically
insulated from one another, and the upper piece also from the arbor C. The width
of the slot in this disc is so proportioned relatively to the width of the end of the
ringing spring K, that when the hand or pointer stands at its normal zero position
(hereinafter called its first open position), or midway between the highest number
or last signal on the dial, and its normal zero position (hereinafter called its second
open position), the end of the spring K is capable of passing through the slot from.
one side of the disc to the other; but when the pointer is in any other position,
the end of the spring K is not capable of so passing through the slot, but is locked
on the one or other side of the disc as it may be placed, and according to whether
or not it was pressed through the slot when the hand or pointer started from its
normal zero or first open position, and if it was so pressed through, it can only
return to the upper side of the disc when the hand comes round to its second open
position.
In Figure 5 the place of the slotted disc is taken by a lever H pivotted at one
end, and pulled in one direction by a spring, its motion being limited by a pair of
studs a, a.
This lever is raised by a cam on the main arbor C when the hand or
pointer is in either of its open positions, but freed by the cam and allowed to move
over by the pull of the spring when the hand is in any other position. The end of
the ringing spring K is capable of passing from one side to the other of the lever H,
when the latter is lifted by the cam, but is not capable of so passing when the
lever is not so lifted. Or the locking arrangement may consist of a slotted cylinder
capable of allowing the ringing spring to pass from the outer to the inner side of
the cylinder, or vice versa, when the band is in either of its "open" positions, but
not so allowing it to pass when the hand is in any other position.
It is evident that the above locking arrangement may be constructed in a
variety of ways, so that a piece of solid material will allow another piece of solid
material to pass from the one side to the other of the first piece, when the hand
or pointer is in either of its "open" positions, but will not so allow it to pass
when the hand is in any other position, but will then lock it on the one side
or the other of the first piece, according as it was placed prior to the land
moving from its first open position, and until the hand comes round to its second
open position.
When the hand or pointer comes opposite to the number or signal denoting the
station in which that particular instrument is placed, the end of the cam I or
arbor C comes into contact with and slightly lifts the ends of two springs, lettered
respectively N and O (see also Figure 1a), and in so doing lifts the upper one N
out of contact with a screw stud c, with which it normally makes contact when
not lifted by the cam. The springs N and O are held by a piece of insulating
material, as indicated in the Drawing, or attached in ony other suitable manner.
The cam I therefore is placed at a different angle relatively to the hand or pointer
in each instrument on the circuit.
Another spring P is secured to the main framework by an insulating attachment
similarly to K and L, and is so placed that when the ringing spring K is pressed
P is allowed to fall upon and inake contact with a screw stud pin metallic

page_text: connection with the main framework; but at other times is held out of contact
with the stud p by means of the spring K, from which it is however insulated.
The internal connections of the call instrument or signal are as follows:-A wire
leads the current from the terminal marked line 1 (or L¹) first to a screw
connection, where it joins a wire from the lightning guard (this may be of any
ordinary form), but consists in the instrument shown of three insulated wires
twisted together and passed into a piece of tube; one end of each of these wires is
then cut off short, and the other ends are joined respectively to the wires leading
from the line 1, or left hand upper terminal, the earth or centre terminal and the
line 2, or right hand terminal.
There is consequently. no road whatever for the ordinary current through the
guard, but should an intense lightning flash come along the line it will fuse the
insulating covering off the wires, and so take the short circuit afforded by their
contact to go direct to earth.
From this point the wire from the L' terminal goes on through the coils of the
electro-magnet D (or if a relay be used through the relay coils instead, the movement
of the relay armature putting the local current on to the coils of D) to the ringing
spring K, which is normally in contact with spring L. A wire then connects the
spring L with the upper spring N which is normally in contact with the screw
stud c, from which another wire conveys the current to the terminal marked line 2,
and secondary 2 (or L² and S²), calling on its way at the screw connection, where it
joins the second wire from the lightning guard.
From the terminal marked local copper (or LC) a wire leads to the cross
spring P, and to the lower spring O of the pair of springs N, O; and from the
main framework B a wire leads to the terminal marked secondary 1 and transmitter
copper (or S¹ and TC).
The switch bell transmitter Figure 3 is the one we prefer to use with our signal
instrument, although others may be employed.
It consists of a transmitter, an induction coil, a switch hook, which may be of
any ordinary form, and an ordinary trembling or vibrating bell for giving a
continuous ring.
The connections are as follows:-
-
A wire leads from the terminal marked secondary 1 and transmitter copper
(or S and TC) to the end of the switch hook, or to the pivot thereof, if a pivoted
hook be used, and from thence on to one pole S of the secondary coil of the
induction coil, and to one pole of the bell coils respectively, as shown.
From the other end S₁ of the secondary coil a wire leads to one of the pair of
terminals T to which the telephone cord or cords are attached. From the other
one of this pair of terminals T a wire leads first to the under stud of the switch
hook (or that stud with which the hook makes contact when the telephone is
banging thereon), and thence to the terminal marked secondary 2 or S².
From the bell post or second electrical pole of the bell actuating apparatus a
wire leads first to the upper stud of the switch hook (or that stud with which the
hook is in contact when the telephone is off the hook), and thence on to the lower
hinge, as shown; from the other side of this hinge the wire goes on to the
transmitter, and from the other side of the transmitter to the upper hinge. From
the other side of the upper hinge a wire goes to one pole P of the primary coil of
the induction coil, and from the other end P' of the primary coil a wire leads
to the terminal marked local zinc or L. Z.
The switch bell transmitter is connected to the call instrument or signal by
wires joining the terminals marked respectively S¹ and T, C, and S on the switch
bell transmitter with the similarly lettered terminals on the call instrument,
as shown.
Points to be observed in Figure 3, are
1. The method of placing the ordinary carbon blocks and rods or Hughes'
microphones, as shown in the Figure, so as to form an effective transmitter; and, 2,
that the bell, together with the primary coil and transmitter, are all placed in.

page_text: series in one circuit, also that the action of [the switch book is to simply short
circuit the bell and so cut out its resistance and stop its sounding when the
telephone is taken off the hook, or to keep the telephone and secondary coils
short circuited and so cut out their resistances when the telephone is hanging on
the hook.
The various stations are connected up in series in one circuit, as shown in
Figure 6, and worked preferably but not essentially on closed circuit, because
then one strong line battery will work the whole circuit and supply all the
instruments thereon, as shewn.
When the hands of all the instruments stand at zero it is open to any subscriber
to call any other by pressing his ringing plunger d. This presses spring K
Figures 1, 2, and 4, through the slot in the disc, and breaks its contact with
spring L, thereby momentarily insulating the line. The armature of the electro
magnet D of every instrument therefore flies back, and the apparatus at all the
stations advances one step, then on the release of the plunger d, spring K will
come back and make contact with the back of the disc H, thereby again completing
the line circuit. The armature of the electro magnet D is therefore again attracted
and the apparatus at all the stations advances another step. By therefore pressing
the plunger d in and out, the calling subscriber can by alternately insulating and
joining up the line circuit bring the apparatus at all the stations round to the
number to which he wants to speak and there stop.
When in this position the cam on arbor C in the instrument at the station so
indicated by making contact with and lifting spring N off its screw stud c breaks the
direct line circuit through that instrument and inserts the telephone and secondary
coil of that station intermediate therein, and by making contact with spring O
puts the local current on to the bell and transmitter together, so that the bell at
that station will continue to ring until answered. The taking of the telephone off*
the hook by the receiving subscriber preparatory to calling "yes" through the
transmitter will however short circuit the bell coils and so stop the bells sounding
and at the same time concentrate the local current on to the transmitter.
It will be seen also that when the ringing spring K at the calling station was
released after the first pressure of the plunger, it did not complete the line circuit
directly in the same manner as it was made before the spring was pressed, but by
making contact with the under side of the disc, which is in metallic connection by
arbor C with the clock frame, completes the line circuit now only through the
telephone and secondary coils, the direct connection of spring K with spring L
being now broken by the latter at this time, simply resting on the upper or
insulated side of the disc. As this consists of an insulated ring of metal the
rubbing of the metallic surfaces as the disc revolves will always keep the contacts
of the springs clean. The telephone and secondary will however still be short
circuited so long as the telephone hangs on the hook, so that it is not necessary to
ring through them notwithstanding that the road through them is opened at the
first return stroke of the plunger; this short circuit is however broken by the
caller taking the telephone off the hook preparatory to listening for receiver to
reply by calling "yes," and although the resistance of two telephones and
secondaries is then thrown into the line circuit, yet since the armatures are all up
against the electro-magnets D, the weakened current is quite sufficient to hold
them there. When the ringing spring K is pressed under the disc also it allows
the lower cross spring P to drop sufficiently to make contact with its screw stud p
in the main frame work, and thereby puts the local current on to the bell and
transmitter, the bell therefore rings until the caller takes the telephone off the
book, when it is stopped by being short circuited and the current is then
concentrated on to the transmitter..
When the telephone is hung up again however this short circuit is again broken
and the bell again rings, thus giving the caller an unmistakeable signal to clear
the line should he tend to omit to do so. This he does by hanging up his telephone
and again pressing the button in and out until the apparatus comes round to zero,

page_text: when the ringing spring K will come up through the slot in the disc, thus lifting
spring P out of contact with its screw stud and stopping the bell by breaking the
local circuit; also by making contact of itself with spring L it will again establish
the line circuit directly, and so render the whole apparatus available for any other
subscriber who may wish to use it. It will be seen that by the above means both
the calling and receiving subscribers had their telephonic apparatus put into
proper condition for speaking to each other, but none of the other subscribers
could have heard anything in consequence of the cams in their instruments not
having put their telephones in circuit; and it is impossible for them to produce
any effect whatever (except to ring their own bells) by pressing their buttons, in
consequence of the slots in the discs having revolved out of position to allow of
spring K being pressed through; it can therefore now only rest on the top of the
disc and put a little pressure thereon, the friction resulting from which the coiled
spring is sufficient to overcome, and spring K cannot therefore now by any ordinary
means be made to break contact with spring L, and consequently the line circuit
cannot be affected in any way whatever by any subscriber but the caller, until the
latter brings the apparatus back to its normal zero position.
The ordinary adjusting screw of the bell mechanism is also let out a little so
that the hammers require to make three or four vibrations before striking the bells.
The latter therefore are not sounded by the short momentary completion of the
local circuit by the cams, as the pointer at each station in turn passes the number
or signal denoting that particular station, but will only be rung at that station at
whose number or signal the caller allows the pointer to stop or remain.
For working on open circuit we apply a ringing battery at each end of the line
with one pole connected to earth and the other pole connected to line, taking care
that the pole which is connected to line be the same in each battery, so that the
batteries are opposed to each other and no sensible current passes.
We then apply in our signal instrument a contact stud attached to the main
framework, but electrically insulated therefrom, but connected by a wire to earth,
and in such position that on pressing the plunger & spring K can make contact
therewith if the slot in the disc H is in position to allow of spring K passing
through, or if it is already on the under side of the disc in consequence of having
been pressed through the slot when the apparatus stood at zero; but this contact
cannot be made if spring K be not so on the under side of the disc H and the
apparatus not at zero in consequence of K being then blocked on the upper side of
disc H, the slot being out of position to allow of it passing through.
According to this method also we electrically connect spring K with the main
framework, and our slotted disc also by this method consists simply of a piece of
insulating material instead of a compound disc as before, since the only effect now
required to be produced by the breaking of the contact of the springs K and L is
simply the breaking of the short circuit through the signal instrument of the
speaking instruments or telephone and secondary, and not as before the entire
breaking of the line circuit to be again joined up by the contact of spring K with
the underside of the disc.
The rationale of working on open circuit is then as follows:-
The instruments standing at zero any subscriber can call by simply pressing his
plunger d, and so pressing spring K through the slot in the disc H on to the earth
stud. This action by breaking the contact of springs K and L breaks the short
circuit through the signal instrument of the speaking instruments or telephone and
secondary, as before mentioned, and by the making contact of spring K with the
earth stud puts an intermediate earth on the line, and so brings the two opposed
batteries at the extremities of the line into action, the one battery working all the
signal instruments on the one side of the caller, including his own instrument, and
the other battery working all the instruments on the other side of the caller; by
then alternately breaking and making the contact of spring K with the earth stud
by means of his plunger d the caller can actuate all the clocks or step by step
motions, stopping at the number to which he wants to speak with his spring K up

page_text: i
against the back of the disc H out of contact with the earth stud; the number so
called will then be rung up, and all effects produced in a manner similar to that
described for working on closed circuit.
The rest of the apparatus would in fact remain intact with the exception that
the hands or pointers would now point to zero or the respective numbers when the
current was off instead of on, as in the closed circuit method.
The above is a complete description of the apparatus as used for connecting up a
number (say twelve) private stations with one another.
For use with telegraphs we insert the telegraphic transmitter and receiver in
place of the secondary and telephone described above, an ordinary switch shunting
the local circuit on or off the call bell, and short circuiting or unshort circuiting
the telegraph instrument in a manner similar to the switch hook described above
for use with telephones.
In the case of a Morse telegraph we adjust the hauling off spring of the
armatures so that the latter may not be attracted by the ordinary permanent
current required to work the call instrument (Figures 1 and 2), but are affected by
the additional battery current put on by the transmitter key.
For A, B, C, step by step or polarized magnet telegraphs we adjust the receivers
so that the polarization in one direction caused by our line current is neutralized
or nearly so by a permanent or electro magnet, so that the receivers may be free to
work the same as if no permanent current were on the line.
And generally our call and locking apparatus is applicable to any form of
telegraph in which the effects of our permanent current can be balanced or elimi-
nated, and which do not produce any momentary insulations of the line; or we
may work on open circuit, and by a relay may, as is well understood, so arrange
that currents in the one direction or of a certain intensity may affect the call
instrument or signal, while those in the opposite direction or of different intensity
may affect only the telegraphic apparatus put into circuit by that call instrument
or signal.
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, substantially as described, in a telephonic or telegraphic
call apparatus of (1) a step by step or clock mechanism controlled by pulsations in
the line current, and capable of being thus set from a distant station to a position
in which alone the telephone or telegraph instrument is in effective connection
with the line wire; (2) a key or contact maker by which such pulsations may be
produced; and (3), a locking device which renders the key inoperative as soon as
the clock is moved from its zero point by an incoming signal.
Second. The combination, substantially as described, consisting of a telephonic
or telegraphic circuit through which a current normally flows, and a series of step
by step or clock mechanism actuated by breaking and making the circuit, and
operating to put the telephone or telegraph instrument into effective connection
with the line wire.
Third. Our improved telephonic and telegraphic apparatus, substantially as
described and illustrated by Figures 1 to 6 of the annexed Drawings.
In witness whereof, we, the said Alfred Charles Brown and Henry Alfred
Charles Saunders, have hereunto set our hands and seals, this Fourth day
of January, in the year of our Lord One thousand eight hundred and eighty
two
A. C. BROWN.
H. A. C. SAUNDERS.
(L.S.)
(L.S.)
+
5