IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC AND TELEPHONIC APPARATUS
Year: 1880

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltino, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
" IMPROVEMENTS IN AND RELATING TO TELEGRAPHIC AND TELEPHONIC
APPARATUS." A communication from abroad by Edward Davis, of Cambridge,
and Peter Ambrose Dowd, of Boston, both in the State of Massachusetts,
United States of America.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissiouers of Patents on the 31st March 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. « IMPROVEMENTS IN AND RELATING TO
TELEGRAPHIC AND TELEPHONIC APPARATUS." [A communication from abroad by
Edward Davis, of Cambridge, and Peter Ambroso Dowd, of Boston, both in the
State of Massachusetts, United States of America.]
This Invention relates to the giving of visible and audible signals by means of
an electric circuit, and comprises,―
First. The combination of two or more instruments in the same circuit, each
instrument consisting of an electro-magnet with two or more armatures, and
mechanism actuated by the movement of the said armatures,) or actuated by clock-
work which is set in motion by the movement of one of said armatures, (the said
mechanism being so contrived that any one of the instruments can be so set as to
sound a local alarm or signal otherwise without sounding the other alarms or
signalling by the other instruments, the object being to signal by any one of a
number of instruments in a single circuit without causing the other instruments in
that circuit to signal.
By this part of the said Invention a certain station (for example, the central
office), can call any one of a large number of stations in one circuit, without at the
same time sounding the bells or giving other signals at the other stations in the
circuit; each station can call the central office without sounding the bells at the
other station in the same circuit; each station can communicate with the central"
office and with any other station; the central office can communicate with any
station without the knowledge of the other stations; any of the stations can be

page_text: connected in order that they may communicate each with the others, and without
the knowledge of any station not connected; and the system and apparatus used
can be made simple, durable, and not easily deranged.
In one form of instrument constructed according to this Invention, one heavy
current, one light current, and one heavy current will so move the parts of one of
the instruments as to sound the alarm, but will not thus move any other instrument
in the series; one heavy, two light, and one heavy will cause another instrument,
say, at station two to signal, but will not cause the instrument at any other station
to signal; one heavy, three light, and one heavy will sound the alarm at station
three, but no other; one heavy, four light, and one heavy at station four, and no
other, and so on, no signal being sounded, except when its own peculiar series of
currents pass over the main circuits.
This form of instrument consists of an electro-magnet with two armatures, each
held away from the poles of the magnet by a coiled spring, the tension on one
spring being greater than on the other, so that when a current of a certain electro-
motive force is sent over the circuit through the coils of the electro-magnet only
one of the armatures is moved; but when a current of a considerably greater
electro-motive force is sent over the circuit aud through the coils, both armatures
are moved. The motion of each armature will move a ratchet wheel one stop by a
pawl attached to the armature; and an insulated leaf spring is so arranged with
reference to each wheel, that metallic contact is mado between each wheel (or some
metal piece moving with it) at a certain point in the revolution of each wheel, and
these insulated leaf springs are the terminals of a local circuit. The instrument at
station No. 1 of circuit No. 1 has its wheels so formed that when it is at unison
the leaf springs are both out of metallic contact with the wheels. If station No. 1
of circuit No. 1 is to be called from the central office, one heavy current is sent over
circuit No. 1, and both armatures are moved, and both wheels revolved one step;
and the wheels are so shaped that a metal projection from the wheel of the heavy
current armature brought so close to its leaf spring, that another notion of the
armature will bring it in contact with that spring, while the projection from the
wheel of the light current armature requires two motions of that armature to bring
it in contact with its leaf spring; a light current is then sent over circuit No. 1,
thereby moving the wheel of the light current armature one step, and bringing its
projection so that another movement of the light current armature will make
contact between the leaf spring and this projection, whereupon one heavy current
is sent over circuit No. 1, and both armatures are moved, both wheels are also
moved each one step, and both projections thereby brought into contact each with
its leaf spring, and the local circuit thereby established; for as both leaf springs are
terminals of a local circuit, and as both are in contact with the metallic projections,
and as these projections are not insulated from the metal shafts of the wheels and
the metal fraine in which these shafts turn, a free passage for the current from the
local battery is established through the local circuit wire, the two leaf springs, the
projections, and the shafts of the wheels or the frame of the instrument, the pro-
jections in contact with the leaf springs not being insulated from the frame of the
instrument.
The instrument at station No. 2 of circuit No. 1 is precisely like the instrument
(just described) at station No. 1, except that the projections are arranged differently,
one heavy current bringing instrument No. 2 from unison, so that the projection of
the heavy current wheel is one step from contact with its leaf spring, but bringing
the projection of the light current wheel so that it is three steps from contact with
its leaf spring; two light currents are then sent over circuit No. 1, moving the light
current wheel two steps, and bringing its projection one step from contact with its
leaf spring; then one heavy current moves both armatures and both wheels, and
thereby makes contact between the two leaf springs, completing the local circuit
and sounding the alarm at station No. 2 of circuit No. 1; and so of instrument
No. 3 on circuit No. 1, one heavy current will move both armatures and both
wheels, and bring the heavy current projection one step from its leaf spring, and

page_text: the light current projection four steps from its leaf spring; then three light
currents will move the light current projection three steps, bringing it but one step
from contact with its leaf spring, and one heavy current will then bring both
projections each into contact with its leaf spring, and make the local circuit. It
will be seen that the series of currents required to so set instrument No. 1 as to
make the local circuit, will also move the armatures of instruments Nos. 2 and 3,
but will leave the parts of the instrument No. 2 so that the light current projection
is still one step from contact with its leaf spring and the parts of instrument
No. 3, so that the light current projection is two steps from contact with its leaf
spring; and in all the other instruments in circuit No. 1 the heavy current pro-
jections will each be in contact with its leaf spring, but the light current projections
will be respectively three, four, or more steps from contact with their respective leaf
springs. Instead of a series of local circuits, each controlled by its instrument, a
series of local alarms may be used, each released when the light and heavy current
wheels are brought into the desired relation, but not released until these wheels are
brought into that relation. By this form of instrument any one of a number of
stations in a single circuit can be called without calling any of the others, the
principle being to cause the instrument to close a local circuit, or otherwise set in
motion a local alarm or other signal.
The wheels may be brought to unison in a variety of ways:-The mode I prefer
is to have one blank spaco instead of a tooth in each ratchet wheel. The pawl of
the heavy current armature works upon both wheels, but the pawl of the light
current armature has two hooks upon it at different levels, one of which works one
wheel only; but when this hook rests in the blank space of that wheel the pawl
falls low enough, owing to the shape of this blank space, to bring the other hook
into mesh with the teeth of the heavy current wheel, and this heavy current wheel
is revolved by the light current pawl until the hook of that pawl rests in the blank
space of that wheel, both hooks of the light current pawl then resting in blank
spaces, while the single hook of the heavy current pawl extends across both wheels
in readiness to move both when the heavy current passes.
After a station has been called a large number of light curronts aro sent through
the circuit, and all the light current wheels are revolved by the light current pawl
until the blank space in each gets under the lowerinost hook of that pawl; that
pawl then falls far enough to bring its upper hook in mesh with the teeth of the
heavy current wheel, which wheel is revolved until its blank space gets under the
uppermost hook of the light current pawl, the light current wheel not moving
while the light current pawl is moving the heavy current wheel, and neither of the
wheels being moved by the motion of the light current pawl when the spaces arc
under the hooks of that pawl. The wheels are in unison when these spaces are
under the hooks of the light current pawl, and this unison can be broken only by
a motion of the heavy current pawl.
Another form of instrument, constructed according to this Invention, consists of
a notched disc or wheel, which is moved rapidly by a series of currents passing
through the coils of an electro-magnet, the disc being moved by the motions of the
armature of the magnet or moved by clock-work, step by step, as the armature is
moved back and forth, releasing the wheel and then stopping it, that is to say, in
one case the wheel is moved step by step by the power of the magnetisın developed
by the current, and in the other it is inoved by the power of a wound up spring,
but its motion, step by step, is controlled by the armature. In this form of
instrument one terminal of the local circuit is a wire at the bottom of the notch
in the disc, and the other terminal is a finger on an arm which rests on the edge
of the disc until the notch in the dise gets under this finger when the arm falls far
enough to bring the finger into contact with the terminal in the notch. The disc
is of hard rubber or has a hard rubber tyre, so that the local circuit is not made
until the finger lies in the notch. The principle of this part of the said Invention
is the familiar one that a notch may be moved under a finger or a finger over a

page_text: notch, and yet the finger be kept from entering the notch if the notch move rapidly
under the finger, or vice versa.
In this form of instrument station No. 1 of circuit No. 1 may be called by a
single current over that circuit; this allows the notched disc to move one step and
thereby brings the notch under the finger, which falls into the notch, and thereby
makes the local circuit or otherwiso gives the local alarm. When two currents are
sent over circuit No. 1 the discs of all the instruments are moved two steps, but
station No. 1 is not called because the two currents are sent in such quick succession
that the notch in the disc of instrument No. 1 passes under its finger before that
finger falls far enough to make the local circuit; but the local circuit is made at
station No. 2, because the disc of instrument No. 2 remains stationary after moving
two steps, and thereby gives its finger time enough to fall into its notch. The
instruments at each station are alike except that the notch is at a different place in
the disc of each.
These instruments may be brought into unison in a variety of ways:-I use a
permanent magnet for the armaturo which controls the notched disc, and to vibrate
that armature by the use of alternate plus and minus currents. This enables me
to use a second armature of soft iron, which remains motionless, or substantially so,
when the currents pass rapidly; but when the currents cease to pass this soft iron
armaturo pulled away from the magnet by the usual spring. An arm projecting
from this soft iron armature lies in the path of a pin projecting from the disc, when
the armature is as close to the magnet as it can get, but lies out of this path except
when the armature is attracted to the inagnet. Consequently after any station has
been called a large number of plus and minus currents are sent in rapid succession
through all the instruments, thereby rotating all the discs rapidly until the unison
pins, one projecting from each disc, bring up each against the arm of its soft iron
magnet, which provents the farther revolution of cach of the discs, bringing each
to unison. When the plus and minus currents cease to pass the unison armatures
are drawn back by their springs and their arms removed out of the path of the
unison pins on the discs, each disc being then controlled only by the main
armature.
Another form of instrument, constructed according to this Invention, consists of
two armatures, each controlling a wheel but both wheels on the same shaft; these
armatures may be both permanent magnets, so arranged with reference to the
electro-magnet that a plus current will attract one of them and a minus current the
other, and this is the form I prefer. The wheel revolved by the minus current is a
ratchet wheel, but has one cam tooth so shaped as to bring the end of the minus
current pawl, when this tooth comes under the hook of the minus pawl, into contact
with a stop and thereby prevent that pawl from revolving the minus ratchet
wheel, the end of the minus pawl coming against its stop and thereby preventing
the full motion of the armature towards the magnet. The other wheel has also a
cam tooth so shaped that when one portion of it is under the hook of its pawl this
plus current pawl is in such relation to its stop that it can move the wheel one
step, but cannot move far enough to sound an alarm or closo a local circuit; another
portion of this plus wheel is so shaped that the plus pawl when its hook rests on
this portion of the plus wheel is brought into contact with its stop and prevented
from moving the plus wheel, and a third portion is so shaped that the plus paw!
can move freely, without regard to its stop and without moving the plus wheel,
when this portion of the plus wheel is under the hook of the plus pawl.
When the instruments are at unison the cam tooth of the minus wheel is under
the hook of the minus pawl, and the can tooth of the plus wheel is in contact or
nearly so with the hook of the plus pawl, so that one plus current through the
magnet will move the plus wheel one step, and thereby move the minus wheel also
one step, both being fast to the same shaft; but this motion of the plus pawl is
arrested by its stop before a hammer carried by it or its armature strikes a bell, or
before it moves far enough to make a local circuit. Then one minus current moves

page_text: the minus wheel one step, and also tho plus wheel ono step, and this motion will
bring that part of the periphery of the plus whool under the plus pawl, which acts
to permit the plus pawl to move freely without regard to its stop. Then a number
of plus currents will vibrate the plus armature and cause a hammer carried by it
to strike a bell; or, if preferred, one plus current will throw forward the plus
armature or pawl far enough to make a local circuit.
The instrument at station two has its minus wheel just like the minus wheel of
the other instruments, but its plus wheel must be moved two steps from unison
before the plus pawl is in such relation to its stop that it can make a full motion,
while at station three tho plus wheel of the instrument must move three steps to
permit of the full motion of the plus armature and pawl, and so on.
To bring these instruments to unison a large number of minus currents are sent
over the circuit, moving both the wheels of each instrument until the cam tooth of
the minus wheel gets under the hook of the minus pawl, and thereby causes the
minus pawl to strike its stop, and making it impossible to move either wheel any
further by a minus current; and when thus brought to unison the half stroke cam
tooth of the plus wheel is under the hook of the plus pawl, so that a single plus
current will move both wheels one step.
The armatures in this form of instrument may bo both soft iron armatures, and
be adjusted for a heavy current and a light current instead of plus and minus
currents. The heavy current would of course move both, unless means were used
to prevent it, and for this purpose I use a third soft iron armature, the spring of
which is so adjusted that the light curront will not operate it, and this extra arma-
ture is so arranged that when it moves towards the magnet it gets between the
magnet and light current armature, and thereby prevents the motion of the light
current armature, consequently when the heavy current passes, although all these
armatures are attracted, the extra armature operates to prevent the motion of tho
light current armature, and the only armaturo which acts to move the wheels when
the heavy current passes is the heavy current armature. The instrument is in all
other respects precisely the same as before described, but is set by, first, a heavy
current, then one or more light currents, instead of, first, a plus current, and then
one or more minus currents; and the alarm is sounded or the local circuit mado
after the instrument is set by the heavy current instead of by the plus current.
The said Invention comprises, secondly, a system of circuits. The main wire is
connected at the central office and at the several stations with a switch, and this
switch is so constructed that when the telephone is in place the circuit is through
this switch direct to the coils of the electro magnet in the calling instrument, and
from these coils to the main line, the coils of each calling instrument being in the
main line when the receiving telephones aro all in place; but the act of taking the
telephone from its holder cuts out the coils of the calling instrument at that station,
the switch moving when the weight of the telephone is removed from it, so that the
current is through the telephone to the main line instead of through the calling
instrument to the main line. This switch can be constructed in a variety of ways
well known to all skilled in the art, as it is not new in itself, the novelty consisting
in the arrangement of a series of calling instruments and a series of telephones in a
single circuit, so that the telephones are all cut out of the circuit when on their
holders, and cach telephone is brought into the circuit by cutting out its calling
instrument by means of a suitable switch, operated by putting the telephone on and
taking it off its holder.
The said Invention comprises, thirdly, a secret system, whereby no telephone can
be used until its calling instrument is properly set.
The wire connecting the telephone to the main line is not connected directly with
the main line, but is connected to an insulated spring on the instrument, and a
wheel or projection, which moves with the moving part of the instrument and is not
insulated from the frame of the instrument, is brought into contact with this spring
when the instrument is set for calling, and this contact completes the connection of
the telephone wire with the main line, that is to say, when the calling instrument

page_text: is set for calling, the telephone wire is connected with the main line, or will be as
soon as the telephone is removed from its holder; but until the calling instrument
is so set the telephone cannot be brought into the circuit. It will be understood
that the main line is connected with the telephone wire by means of a moving part
on the instrument and a contact piece, which are kept separate so as to cut the
telephone out of the circuit until the instrument is set. In this system no telephone
ou the circuit can be used until its instrument is set, and this prevents any prying
into the conversation between any stations of the circuit.
The said Invention comprises, fourthly, a central switch for connecting together
any two or more of a large number of circuits. The circuits to be connected together
are each connected with a series of metallic pieces, which are out of contact with
cach other, and which extend across a suitable insulating base, one end of the circuit
wire being connected to one line of these pieces, and the other end to a line of pieces
parallel with the first line, so that when the pieces composing the first of these
parallel lines are connected by means of movable pieces of metal the circuit is com-
plete, say, from top to bottom of the upper surface of the baso; and when the pieces
composing the other of these parallel lines are connected by means of other movable
pieces the circuit is complete from bottom to top of the upper surface of the base,
assuming that the ends of these parallel lines running from top to bottom of the
upper surface of the base are in metallic contact. A number of circuits are thus
arranged, each extending in two lines from top to bottom of the upper surface of
the base. For illustration, say there are four pairs of these lines or pieces, or eight
lines in all, on the upper surface of the base, each line parallel with the others, and
that these four pairs of lines of pieces compose with the four pairs of lines of
anovable pieces four complete metallic circuits; on the under surface of the base
thero are also four pairs of lines of pieces connected to four pairs of lines of movable
pieces, but these under lines lie crosswise of the upper lines, and each pair of under
lines with its movable pieces constitutes also a complete metallic circuit. This
switch, therefore contains eight circuits in all, four of which cross the other four.
Now suppose that the odd numbered circuits, 1, 3, 5, and 7, are in the upper surface
of the base plate, and the even numbered circuits in the lower surface of the base
plate, and suppose also that it is desired to connect circuits 1 and 2, then tho
movable pieces on the upper surface of the base plate where 1 crosses 2 are removed
or shifted so as to break circuit, one at that point, and the same thing is done with
circuit 2 on the under surface of the base plate when it crosses circuit 1; then the
four metallic pieces on the upper surface of the base plate are brought into metallic
contact with the four metallic pieces just below them on the lower surface of the
base plate, so that the circuit is established through the wire of circuit 1 to one of
the metallic pieces on the upper surface of the base plate, and then by means of con-
necting metal pieces down through the base plate to one of the metallic pieces of circuit
2, just below the metallic piece before mentioned of circuit 1, thence sidewise across
the outer surface of the base plate through circuit 2 and back through the wire of
circuit 2 and its line of metal pieces on the base plate to the second inetallic piece
of circuit 2, thence by the connecting piece up through the base plate, thence by
one line of metallic pieces of circuit 1 from top to bottom of the upper surface of
the base plate and back by the parallel line from bottom to top, thence down again
through the base plate to the third metallic piece of circuit 2, thence sidewise down
one line of circuit 2 and back by the parallel lines, thence up through the base plate
to circuit 1 again. In brief, removing the two connecting pieces from circuit 1 and
the two connecting pieces from circuit 2 when they cross cach other, and connecting
the four metal pieces of circuit one with the corresponding pieces of circuit 2 will
make circuits one and two into a single metallic circuit; and this is true of any
other two circuits which cross cach other.
This part of the said Invention consists in arranging the circuits which are to be
connected so that each shall cross all the others to which it is to be connected, and
so cross that each may be broken in two places, so that four ends are left in each;
and, consequently, when the first end of circuit 1 is joined to the corresponding end

page_text: of circuit 2, the second end of circuit 1 to the corresponding end of circuit 2, the
third end of circuit 1 to the corresponding ond of circuit 2, and the fourth end of
circuit 1 to the corresponding end of circuit 2, the two circuits will make a singlo
circuit. It will be obvious that after two circuits have thus been made into one, a
third circuit may be in like manner connected with the compound circuit, and so to
any extent; for all the circuits connected with this central switch board may be
made into one.
Various mechanical devices may be used for moving the movable pieces; it is
preferred to arrange them on a hard rubber plug, one of which extends through a
hole in the baso board at each point where any two circuits cross. This plug has
connected to it near its upper end two spring metal pieces, one on each side, which
servo to make metallic connection between the pieces on the upper surface of the
base plate, and also has two like springs connected to it near its lower end which serve
to make metallic connection between the pieces on the under surface of the baso
plate, the latter pair of springs lying crosswise of the first pair. It also has
connected to it four up and down metal springs which serve to connect the four
upper pieces with the four lower pieces; these plugs are commonly so placed that
the crosswise springs bear one upon one pair of metal pieces on the upper surfaco
of the base plato, the second upon two other pieces upon the upper surface of the
baso plate, and the third and fourth connect the corresponding picco on the lower
surface of the base plate, and when thus placed the four up and down springs rest
against the base plate; but if the plug be turned a quarter of a circle the up and
down springs connect the upper and lower metal pieces, and the other springs are
out of contact with these metal pieces and rest only on the base plate.
By means of this Invention a number of telephones or other electrical instruments
can be used in one circuit, each practically independent of the others; for each
station can be called from the central office, and each can call the central office by
means too well known to need description (and if desirable each station can be
provided with an automatic circuit breaker by which it can call any other station
in the same circuit).
The aforesaid system by which the telephone or other electrical instrument is cut
out of the circuit until the calling instrument is properly set to bring it in is a
feature which has long been desired for telephone service, and which is applicable
in many other cases.
The miode herein described of connecting the telephone or other electrical
instrument and the calling instrument with the circuit by means of a switch, so
that one is always out of the circuit while the other is in, is an important feature
of this Invention, as it admits of calling any other station in that circuit without
working the instrument at the station where the telephone is removed from its
holder; it also makes the resistance less than if the circuit were through both the
telephone coils and the instrument coils.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lako in the Great Seal Patent Office on the 29th
September 1880.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "IMPROVEMENTS IN AND RELATING TO
TELEGRAPHIC AND TELEPHONIC APPARATUS." A communication from abroad by
Edward Davis, of Cambridge, and Peter Ambrose Dowd, of Boston, both in the
State of Massachusetts, United States of America.
This Invention relates to the giving of visible and audible signals by means of
an electric current, and comprises,―
First. The combination of two or more instruments in the same circuit, each
instrument consisting of an electro-magnet with two or more armatures, and
mechanism actuated by the movement of the said armatures (or actuated by clock-
work which is set in motion by the movement of one of the said armatures), the
said mechanism being so contrived that any one of the instruments can be so set as
to sound a local alarm or signal otherwise without sounding the other alarms_or
signalling by the other instruments, the object being to signal by any one of a
number of instruments in a single circuit without causing the other instruments in
that circuit to signal.
By this part of the said Invention a certain station (for example the central
office) can call any one of a large number of stations in one circuit without at the
same time sounding the bells or giving other signals at the other stations in the
circuit; each station can call the central office without sounding the bells at the
other stations in the same circuit; each station can communicate with the central
office and with any other station; the central office can communicate with any
station without the knowledge of the other stations; any of the stations can be
connected in order that each of them may communicate with the others and
without the knowledge of any station not connected; and the system and apparatus
used can be made simple, durable, and not easily liable to derangement.
In one form of instrument constructed according to this Invention one heavy
current, one light current, and one heavy current will so move the parts of one of
the instruments as to sound the alarm, but will not thus move any other instrument
in the series; one heavy current, two light currents, and one heavy current will
cause another instrument, say at station two, to signal, but will not cause the
instrument at any other station to signal; one heavy current, three light currents,
and one heavy current will sound the alarm at station three, but no other; one
heavy current, four light currents, and one heavy current at station four, and no
other, and so on, no signal being sounded except when its own peculiar series of
currents pass over the main circuit. This form of instrument consists of an clectro-
magnet with two armatures, cach held away from the poles of the magnet by a
coiled spring, the tension on one spring being greater than on the other, so that
when a current of a certain electro-motive force is sent over the circuit through tho
coils of the electro-magnets only one of the armatures is moved; but when a
current of a considerably greater electro-motive force is sent over the circuit and
through the coils both armatures are moved. The motion of each armature will
move a ratchet wheel one step by a pawl attached to the armature; and an insulated
leaf spring is so arranged with reference to each wheel that metallic contact is
nade between each wheel (or some metal piece moving with it) at a certain point
in the revolution of each wheel; and these insulated leaf springs are the terminals
of a local circuit. The instrument at station No. 1, of circuit No. 1, has its wheels
so formed that when it is at unison the leaf springs are both out of metallic contact
with the wheels; if station No. 1, of circuit No. 1, is to be called from the central
office one heavy current is sent over circuit No. 1, and both armatures are moved,

page_text: and both wheels revolved one step; and the wheels are so shaped that a metal
projection from the wheel of the heavy current armature is brought so close to its
leaf spring that another motion of the armature will bring it in contact with that
spring; while the projection from the wheel of the light current armature requires
two motions of that armature to bring it in contact with its leaf spring; a light
current is then sent over circuit No. 1, thereby moving the wheel of the light
current armature one step and bringing its projection into such a position that
another movement of the light current armature will make contact between the
leaf spring and this projection; whereupon one heavy current is sent over circuit
No. 1 and both armatures are moved, both wheels are also moved each one step,
and both projections thereby brought into contact cach with its leaf spring, and
the local circuit thereby established; for as both leaf springs are terminals of a
local circuit, and as both are in contact with the metallic projections, and as these
projections are not insulated from the metal shafts of the wheels and the metal
frame in which these shafts turn a free passage for the current from the local
battery is established through the local circuit wire, the two leaf springs, the
projections, and the shafts of the wheels, or the frame of the instrument, the
projections in contact with the leaf springs not being insulated from the frame of
tho instrument.
The instrument at station No. 2 of circuit No. 1 is precisely like the instruments just
described at station No. 1, except that the projections are arranged differently, one
heavy current bringing instrument No. 2 from unison, so that the projection of the
heavy current wheel is one step from contact with its leaf spring, but bringing the
projection of the light current wheel so that it is three steps from contact with its
leaf spring. Two light currents are then sent over circuit No. 1, moving the light
current wheel two steps, and bringing its projection one step from contact with its
leaf spring, then one heavy current moves both armatures and both wheels, and
thereby makes contact between the two leaf springs, completing the local circuit
and sounding the alarm at station No. 2 of circuit No. 1; and with regard to instru-
ment No. 3 on circuit No. 1, one heavy current will move both armatures and both
wheels, and bring the heavy current projection one step from its leaf spring, and
the light current projection four steps from its leaf spring, then three light currents
will move the light current projection three steps, bringing it but one step from
contact with its leaf spring, and one heavy current will then bring both projections
each into contact with its leaf spring, and make the local circuit. It will be seen
that the series of currents required to so set instrument No. 1 as to make the local
circuit will also move the armatures of instruments Nos. 2 and 3, but will leave the
parts of instrument No. 2 so that the light current projection is still one step from
contact with its leaf spring, and the parts of instrument No. 3 so that the light
current projection is two steps from contact with its leaf spring, and in all the other
instruments in circuit No. 1 each heavy current projection will be in contact with
its leaf spring, but the light current projections will be respectively three, four, or
more steps from contact with their respective leaf springs. Instead of a series of
local circuits, each controlled by its instrument, a series of local alarmns may be used,
cach released when the light and heavy current wheels are brought into the desired
relation, but not released until these wheels are brought into that relation. By
this form of instrument any one of a number of stations in a single circuit can be
called without calling any of the others, the principle being to cause the instrument
to close a local circuit or otherwise set in motion a local alarm or other signal.
The wheels may be brought to unison in a variety of ways. The mode I prefer
is to have one blank space instead of a tooth in each ratchet wheel. The pawl of
the heavy current armature works upon both wheels, but the pawl of the light
current armature has two hooks upon it at different levels, one of which works one
wheel only; but when this hook rests in the blank space of that wheel the pawl
falls low enough, owing to the shape of this blank space, to bring the other hook
into mesh with the teeth of the heavy current wheel, and this heavy current wheel

page_text: is revolved by the light current pawl until the hook of that pawl rests in the blank
space of that wheel, both hooks of the light current pawl then resting in blank
spaces, while the single book of the heavy current pawl extends across both wheels,
in readiness to move both when the heavy current passes.
After a station has been called a large number of light currents are sent through
the circuit, and all the light current wheels are revolved by the light current pawls
until the blank space in each is under the lowermost hook of that pawl; that pawl
then falls far enough to bring its upper hook in gear with the teeth of the heavy
current wheel, which wheel is revolved until its blank space is under the uppermost
hook of the light current pawl, the light current wheel not moving while the light
current pawl is moving the heavy current wheel, and neither of the wheels being
moved by the motion of the light current pawl when the spaces are under the hooks
of that pawl. The wheels are in unison when these spaces are under the books of
the light curront pawl, and this unison can be broken only by a motion of the heavy
current pawl.
In the accompanying Drawings Figures 1, 2, 3, 4, and 5 illustrate this form of
my instrument, Figure 1 being a plan of the said instrument, Figure 2 a side view,
and Figures 3, 4, and 5 detail views showing the shape of the light and heavy
current wheels and their pawls and other parts.
A represents the magnet; a¹, a³, its armatures; a, a, its pawls; and aº, a", its
wheels. Each wheel is shewn with an arm a7 or a projecting from its shaft, which
arm comes in contact with one of the blocks a, a, of hard india-rubber or other
insulating material, and in these blocks are the metal pieces a", a¹, which are
connected electrically with the local circuit a¹³, so that when the arm a³ is in contact
with the piece ¹, and the arm as with the piece a¹³, the local circuit is complete ;
or the pieces all and a" may be light latches, cach preventing the motion of ono
wheel in a train of clockwork as, as shewn in Figure 6, and cach moved by one
of the arms a7, as, so that when, but not until, both are moved the train a" is
free to move. This train a is a convenient form of mechanical alarm or signalling
instrument.
Another form of the said instrument consists of a notched disc or wheel which is
moved rapidly by a series of currents passing through the coils of an electro-magnet,
the disc being moved by the motions of the armature of the magnet, or by clock-
work, step by step. as the armature is moved back and forth, releasing the wheel
and then stopping it; that is to say, in one case the wheel is moved step by step
by the power of the magnetism developed by the current, and in the other it is
moved by the power of a wound up spring but its motion step by step is controlled
by the armature. In this form of instrument one terminal of the local circuit is a
wire at the bottom of the notch in the disc, and the other terminal is a finger on an
arm which rests upon the edge of the disc until the notch in the disc is under this
finger, when the arm falls far enough to bring the finger into contact with the
terminal in the notch, or the notch and finger may otherwise control the two
terminals. The disc is of hard india-rubber, or has a hard india-rubber tire, so that
the local circuit is not made or other signal given until the finger lies in the notch.
This part of the said Invention is based upon the principle whereby a notch may be
moved under a finger or a finger over a notch, and yet the finger be kept from
entering the notch if the notch move rapidly under the finger, or vice versa.
In this form of instrument station No. 1 of circuit No. 1 may be called by a
single current over that circuit; this allows the notched disc to move one step, and
thereby brings the notch under the finger which falls into the notch, and thereby
makes the local circuit, or otherwise gives the local alarm. When two currents are
sent over circuit No. 1, the discs of all the instruments are moved two steps, but
station No. 1 is not called because the two currents are sent in such quick succession
that the notch in the disc of instrument No. 1 passes under its finger before that
finger falls far enough to make the local circuit; but the local circuit is made at
station No. 2, because the disc of instrument No. 2 remains stationary after

page_text: moving two steps, and thereby gives its finger timo enough to fall into its notch.
The instruments at each station are alike except that the notch is at a difforent
place in the disc of each.
These instruments may be brought into unison in a variety of ways. The way
I have adopted is to uso a permanent magnet for the armature which controls the
notched disc, and to vibrate that armature by the use of alternate plus and minus
currents. I am thereby enabled to use a second armature of soft iron which
remains motionless, or substantially so, when the currents pass rapidly; but when
the currents cease to pass, this soft iron armature is pulled away from the magnet
by the usual spring. An arm projecting from this soft iron armature lies in the
path of a pin projecting from the disc, when the armature is as close to the magnet
ns it can get, but lies out of this path except when the armature is attracted to the
magnet. Consequently after any station has been called, a large number of plus
and minus currents aro sentin rapid succession through all the instruments, thereby
rotating all of the discs rapidly until cach of the unison pins (one projecting from
each disc) comes in contact with the arm of its soft iron magnet which prevents the
further revolution of each of the discs bringing each to unison. When the plus
and minus currents cease to pass, the unison urinatures are drawn back by their
springs, and their arms removed out of the path of the unison pins on the discs,
cach disc being then controlled only by the main armature.
This form of instrument is shown in Figures 7, 8, 9, and 10 of tho Drawings,
Figure 7 being a plan, and Figure 8 an elevation of the said instrument; Figure 9
an elevation partly in section of a portion of Figure S, with some of tho parts in
a different position; Figure 10 is an clevation of a mechanical aların heroinafter
referred to.
Referring to these Figures H represents a permanent magnet whose office is to
make the vibrating picce a magnet by induction, that is to say, the pieco / is
what is commonly called a "polarized arinature," and is vibrated by plus and
minus currents through the coils of the magnet h. The wheel is moved by the
clockwork shewn one step at every vibration of the armature h, and carries with
it the disc h. The finger ¹ carries one electrode b of the local circuit, and this
electrode b cannot come into contact with the other electrode b¹ of the local circuit
until the finger h¹ falls into the notch in the disc ho. The plus and minus currents
which cause the armature h to vibrate, also cause the soft iron armature h³ to
remain close to the magnet, the currents being sent rapidly through the coils of
the magnet, and the armature h³ holds up the finger h¹ as long as the currents pass
rapidly, but when the currents cease the finger h¹ is no longer held up by the
arinature h³, but is pulled down by its spring.
The unison pin strikes the end of the finger h², while that finger is held up
by the armature ³, and thus all of the wheels h² and discs h³ are brought into
unison.
The finger may release the detent of the mechanical alarm h³, as shown in
Figure 10, instead of making a local circuit as in Figures 7, 8, and 9.
Another form of instrument operating on the same principle is shown in
Figures 11, 12, 13, 14, 15, and 10 of the Drawings.
Figures 11 and 13 aro perspective views, Figure 12 a front view with the cover
removed, and Figure 14 a detail view of the said instrument; Figure 15 is a
vertical section, and Figure 16 a horizontal section of the same.
In theso Figures & represents a polarized armature; c, d, pawls; d³, a ratchet
wheel; d, its arbor; d, the notched disc; d, an index; d, a permanent magnet for
polarizing the armature ; d³, an electro-magnet for vibrating the armature d, and
thereby revolving the arbor d with the disc d and index ; a second magnet d
controls a soft iron armature do, and prevents its tooth du from entering the notch
in the disc d³ so long as the current passes. The finger on the armature d¹º carries
the electrode b of the local circuit, the other electrode b¹ being beneath it.
When the currents, alternately plus and minus, pass rapidly through the coils of
the magnets, the armature d is vibrated, thereby revolving the arbor d', the

page_text: disc d³, and index dª carried by it, but the armature do is held up by its magnet.
When the currents cease the armature do falls, and if the notch in the disc dis
under the tooth d" the local circuit is made by the electrodes b and b¹ coming into
contact. The unison stop d¹ arrests the motion of the disc d by means of the
unison pin d³, and by this means all the instruments are brought to unison, and
the indices to zero on the dial; tho armature to and the unison stop d' then full,
the upper arm of the stop moving the unison pin slightly, so that the lower
arm of the unison stop will strike on the other side of the unison pin when the
-magnet & again attracts the armature (1º.
Another form of instrument constructed according to this Invention consists of
two armatures, each controlling a wheel, but both wheels on the same shaft.
These armatures may be both permanent magnets, so arranged with reference to tho
electro-magnets that a plus current will attract one of them and a minus current
the other.
The wheel revolved by the minus current is a ratchet wheel, but has one cam
tooth so shaped as to bring the end of the minus current pawl, when this tooth
comes under the hook of the minus pawl, into contact with a stop, and thereby
prevent that pawl from revolving the minus ratchet wheel, the end of the minus
pawl coming against its stop and thereby preventing the full motion of the armaturo
towards the magnet. The other wheel has also a cam tooth so shaped that when
one portion of it is under the hook of its pawl this plus current pawl is in such
relation to its stop that it can move the wheel ono step, but cannot move far enough
to sound an alarm or close a local circuit. Another portion of this plus-wheel is so
shaped that the plus pawl when its hook rests on this portion of the plus wheel is
brought into contact with its stop and prevented from moving the plus wheel; and
a third portion is so shaped that the plus pawl can move freely without regard to
its stop, and without moving the plus wheel when this portion of the plus wheel is
under the hook of the plus pawl.
When the instruments are at unison the cam tooth of the minus wheel is under
the hook of the minus pawl, and the cam tooth of the plus wheel is in contact or
nearly so with the hook of the plus pawl, so that one plus current through the
magnet will move the plus wheel one step, and thereby movo the unison wheel also
one step, both being fast to the same shaft; but this motion of the plus pawl is
arrested by its stop before a hammer carried by it, or its armature, strikes a bell, or
before it moves far enough to make a local circuit. Then one minus current moves
the minus wheel one step, and also the plus wheel one step; and this notion will
bring that part of the periphery of the plus wheel under the plus pawl, which acts
to permit the plus pawl to move freely without regard to its stop. Then a number
of plus currents will vibrate the plus armature and cause a haminer carried by it
to strike a bell, or if preferred one plus current will throw forward the plus
armature or pawl far enough to make a local circuit.
The instrument at station two bas its minus wheel just like the minus wheels of
the other instruments, but its plus wheel must be moved two steps from unison
before tho plus pawl is in such relation to its stop that it can make a full motion.
While at station three the plus wheel of the instrument must move three steps to
allow of the full motion of the plus armature and pawl, and so on.
To bring these instruments to unison a large number of minus currents are sent
over the circuit, moving both the wheels of each instrument until the cam tooth of
the minus wheel is under the hook of the minus pawl, and thereby causes the
minus pawl to strike its stop and make it impossible to move either wheel any
farther by a minus current; and when thus brought to unison the half stroke cam
tooth of the plus wheel is under the hook of the plus pawl, so that a single plus
current will move both wheels one step.
The armatures in this form of instrument may be both soft iron armatures, and
be adjusted, for a heavy current and a light current, instead of plus and minus
currents. The heavy current would move both unless means were used to prevent
it; and for this purpose I use a third soft iron armature, the spring of which is so

page_text: adjusted that the light current will not operate it; and this extra armature is so
arranged that when it moves towards the magnet it gets between the magnet
and light current armature, and thereby prevents the motion of the latter.
Consequently when the heavy current passes, although all three armatures are
attracted, the extra armature operates to prevent the motion of the light current
armature, and the only armature which nets to move the wheels when the heavy
current passes is the heavy current armature. The instrument is in all other
respects precisely the same as that above described, but is set by first a heavy
current, and then one or more light currents, instead of first a plus current, and
then one or more minus currents, and the alarm is sounded or the local circuit
made (after the instrument is set) by the heavy current instead of by the plus
current.
In Figures 17 and 18, which are a plan and vertical section, f.f¹, are two
polarized armatures so arranged between the poles f, fs, of the electro-magnet that
when a plus current is sent through the coils of that magnet only one of these
arinatures is moved. The armaturo f carries a bell hammer f10, which strikes the
bell funless a stop f³, see Figures 19 and 20, prevents; this is the armature moved
forward by the plus current; its pawl forests upon the wheel f', which is so
shaped that the pawl fo comes into contact with the stop f beforo the hammer
strikes the bell when the pawl tooth is in the smaller notch of the wheel f", as
shewn in detail in elevation in Figure 19; but the hammer is free to strike tho
bell when the pawl tooth is in the larger notch, as in the detail view Figure 20.
The other armature f', which is the minus current armature, also has a pawlf
which rests upon the ratchet wheel, see the detached views Figures 21 and 22.
When a minus current passes tho armature f¹ is moved forward, and its pawl
moves the wheel f" (and with it the wheel ƒ7, both wheels being fast to one shaft)
except when in the position shewn in Figure 21 when the instrument is at
unison.
In Figures 23, 24, 25, and 26, which represent respectively a plan, a longitudinal
section, looking from one side, a transverse section, and a longitudinal section
looking from the other side, g,g',g, are armatures of soft iron. The armatures g, g²,
correspond exactly to the armatures f¹, of the instrument last herein described
with the exception that the armature g is moved forward only by a heavy current
instead of a plus current, and the armature g' is moved forward only by a light
current instead of by a minus current. To prevent the motion of the armature g¹
when a heavy current is sent through the coils of the magnet g³ the armature g² is
used; this armature is attracted by a heavy current, but not by a light current, and
by its motion towards the magnet ³ arrests the motion of the armature g¹ when a
heavy current passes.
The said Invention comprises,-
Secondly. The system of circuits. The main wire is connected at the central
office and at the several stations with a switch; and this switch is so constructed
that when the telephone is in place the circuit is through this switch direct to the
coils of the electro inagnet in the calling instrument, and from these coils to the
main line, the coils of each calling instrument being in the main line when the
receiving telephones are all in place; but the act of taking the telephone from its
holder cuts out the coils of the calling instrument at that station, the switch
moving when the weight of the telephone is removed from it, so that the current
is through the telephone to the main line instead of through the calling instrument
to the inain line. The construction of this switch may be varied or modified as it
is not new in itself, the novelty of this part of my Invention consisting in the
arrangement of a series of calling instruments, and a series of telephones in a
single circuit, so that the telephones are all cut out of the circuit when on their
holders; and each telephone is brought into the circuit by cutting out its calling
instrument by means of a suitable switch operated by putting the telephone on
and taking it off its holder.
One form of this switch is shown in Figure 11, in which j, j', are two spring

page_text: fingers connected by the insulated bridge piece ; this piece j' is carried by the
spring hook, which supports the telephone when not in use, the weight of the
telephone depressing the shank of the hook against the stop j; the bridge-piece j
is in contact with both the spring fingers j,, when the book is depressed.
Figures 28 and 29 are diagrams illustrating this part of the said Invention.
The line in is fast to a screw cup 3, and passes then to the finger j, and when the
hook is depressed by the weight of the telephone j³, by bridge piece j² to finger j¹,
thence through the coils of the magnets and d to the screw cup 6, to which the
line out is fast, that is to say, when the telephone of any instrument is hung on its
hook the current passes through the coils of the magnets of that instrument, and
the telephones are out of the circuit.
In Figure 29 the telephone j³ is off its hook and consequently the bridge
piece is removed from contact with the fingers j, j¹, so that the current can no
longer pass from j to j; and the circuit is by line in from screw cup 3 to finger j,
thence by the wire jo to the contact point j, with which the spring shank of the
hook is now in contact, thence by hook and wire ³ to the screw cup 2 through
the telephones and jo to the screw cup G and line out. In all the diagrams the
wire is shewn as a part of the local circuit, this being a feature of the secret
system hereinafter described; when that secret system is not used the wire j³ will
extend directly from the hook to the screw cup 2.
The said Invention comprises, thirdly, a secret system whereby no telephone can
be used until its calling instrument is properly set.
The wire connecting the telephone to the main line is not connected directly
with the latter, but is connected to an insulated spring on the instrument, and a
wheel or projection which moves with the moving part of the instrument, and is
not insulated from the frame of the instrument, brought into contact with this
spring when the instrument is set for calling; and this contact completes the
connection of the telephone wire with the main line, that is to say, when tho
calling instrument is set for calling, the telephone wiro is connected with the main
line, or will be as soon as the telephone is removed from its holder, but until the
calling instrument is so set the telephone cannot be brought into the circuit. It
will be understood that the main line is connected with the telephone wire by
means of a moving part on the instrument, and a contact piece, which are kept
separate so as to cut the telephone out of the circuit until the instrument is set.
In this system no telephone in the circuit can be used until its instrument is set;
and this prevents any prying into the conversation between any stations on the
circuit.
The diagrams, Figures 27 to 31, illustrate this secret system; also the signalling
by a local circuit, and also the electrical connections of that form of instrument
shewn in Figures 11 to 10; they also serve to elucidate the electrical connections
of the other forms of instrument.
In these diagrams the "line in" is fast to the screw cup 3, thence to the finger j,
thence by the bridge picce j and finger j' through the coils of the magnets do, do,
to the screw cup 6 and "line out," if the telephone 7 is on its hook, as it will be
before the instrument is set for signalling. The passage of the proper currents
through the coils of the magnets d, do, having set the instrument for signalling
the local circuit is established from the local battery to the screw cup 4, thenco
through the metal plate Y and armature 10 by the electrodes b, b', of the local
circuit and wire to the finger k, and by the bridge picco (which is fast to but
insulated from the hook 3, being in all respects like the bridge picco) to tho
finger, thence to the screw cup 5, and through the call bell to the local battery.
The bridge piece 2 is in contact with both fingers h, k, so long as the telephone is
on its hook, where it will be until the call bell of the local circuit rings. The
diagram, Figure 30, shows the local circuit established. When the call bell rings
the telephone is taken from its hook, and the hook rises, its shank coming into
contact with the point 7, and both the bridge pieces and breaking connection
between the fingers j, j, and h, ; this breaks the local circuit at h, ¹, and also

page_text: cuts out the magnets ³, dº, and establishes a new main circuit from the "line in "
(screw cup 3) to the finger j, thence by the wiro 7, the contact point 7, hook j³,
and wire, through the electrodes b, b', armature do, plate Y, and wire ", to the
screw cup 2, through the telephone to the screw cup 1; by wire 10 to the screw
cup 8, and through the other telephone to the screw cup 7, or "line out," which
is connected with the screw cup 6 by the wire j
The said Invention comprises, fourthly, a central switch for connecting any two
or more of a large number of circuits. These circuits are cach connected with a
series of metallic pieces which are out of contact with each other, and which extend
across a suitable insulating base, one end of the circuit wire being connected to
one line of these pieces, and the other end to a line of pieces parallel with the first
line, so that when the pieces composing the first of these parallel lines are connected
by means of movable pieces of metal, the circuit is complete, say, from top to
bottom of the upper surface of the base; and when the pieces composing the other
of these parallel lines are connected by means of other movable pieces the circuit is
complete from bottom to top of the upper surface of the base, assuining that the ends
of those parallel lines running from top to bottom of the upper surface of the base
are in metallic contact. A number of circuits are thus arranged each extending in
two lines from top to bottom of the upper surface of the base; for illustration, say
there are four pairs of these lines of pieces or eight lines in all on the upper surface
of the base, each line parallel with the others, and that these four pairs of lines of
pieces compose with the four pairs of lines of movable pieces four complete metallic
circuits. On the under surface of the base there are also four pairs of lines of
pieces connected by four pairs of lines of movable pieces, but these under lines lie
crosswise of the upper lines, and each pair of underlines with its movable pieces
constitutes also a complete metallic circuit. This switch therefore contains eight
circuits in all, four of which cross the other four. Now suppose that the odd
numbered circuits 1, 3, 5, and 7, are on the upper surface of the base plate, and the
even numbered circuits on the lower surface of the base plate, and suppose also
that it is desired to connect circuits 1 and 2, then the movable pieces on the upper
surface of the base plate, where 1 crosses 2, are removed or shifted, so as to break
circuit 1 at that point, and the saine thing is done with circuit 2. on the under
surface of the base plate when it crosses circuit 1 then the four metallic pieces
on the upper surface of the base plate are brought into metallic contact with the
four metallic pieces just below them on the lower surface of the base-plate, so that
the circuit is established through the wire of circuit 1 to one of the metallic pieces
on the upper surface of the base plate, and then by means of connecting metal
picces down through the base plate to one of the metallic pieces of circuit 2, just
below the metallic piece before mentioned of circuit 1, thence sidewise across the
under surface of the base-plate through circuit 2 and back through the wire of
circuit 2 and its line of metal pieces on the base-plate to the second metallic piece
of circuit 2; thence by the connecting piece up through the base-plate; thence by
one line of metallic pieces of circuit 1 from top to bottom of the upper surface of
the base-plate and back by the parallel line from bottom to top; thence down
again through the base plate to the third metallic piece of circuit 2, thence side-
wise down over line of circuit 2 and back by the parallel lines; thence up through
the base plate to circuit 1 again; in brief, removing the two connecting pieces
from circuit 1, and the two connecting pieces from circuit 2 when they cross each
other, and connecting the four metal pieces of circuit 1 with the corresponding
piece of circuit 2 will make circuits 1 and 2 into a single metallic circuit; and
this is true of any other two circuits which cross each other.
This part of the said Invention consists in arranging the circuits which are to
be connected so that each shall cross all the others to which it is to be connected
and so cross that each may be broken in two places so that four ends are left in
each, and consequently when the first end of circuit 1 is joined to the corresponding
end of circuit 2, the second end of circuit 1 to the corresponding end of circuit 2,
the third end of circuit 1 to the corresponding end of circuit 2, and the fourth end

page_text: of circuit 1 to the corresponding end of circuit 2 the two circuits will make a
single circuit. It will be obvious that after two circuits have thus been made into
one a third circuit may be in like manner connected with this compound circuit;
and so to any extent for all the circuits connected with this central switch-board
may be made into one.
This
Various mechanical devices may be used for moving tho movable pieces. It is
preferred to arrange them on a hard india-rubber plug, one of which extends
through a hole in the base board at each point where any two circuits cross.
plug has connected to it near its upper end two spring metal pieces one on each
side, which pieces serve to make metallic connection between the pieces on the 1
upper surface of the base-plate, and the said plug also has two like springs con-
nected to it near its lower end which serve to make metallic connection between
the pieces on the under surface of the base-plate, the latter pair of springs lying
crosswise of the first pair. It also has connected to it four up and down metal
springs, which serve to connect the four upper pieces with the four lower pieces.
These plugs are ordinarily so placed that tho crosswise springs bear one upon one
pair of metal pieces on the upper surface of the base plate, the second upon two
other pieces upon the upper surface of the base plate, and the third and fourth
connect the corresponding piece on the lower surface of the base plate, and when
thus placed the four up and down springs rest against the base-plate; but if the
plug be turned to the extent of a quarter of a circle the up and down springs
connect the upper and lower metal pieces, and the other springs are out of contact
with these metal pieces and rest only on the base plate.
Figures 32 to 39 illustrate this part of the said Invention.
Figure 32 is a plan of my improved switch board, and
Figure 33 is an underside view of a portion of the same.
Figures 34, 37, 38, and 39 are diaphragms, and
Figures 35 and 30 aro perspective views of metal pieces hereinafter described
and the plug and devices for completing the circuit between the same, the said
plug being shewn in different positions.
This part of the said Invention is based upon making two breaks in each of the
two circuits to be connected, thus leaving four ends to each circuit, as illustrated by
the diagram, Figure 34, where the full lines 8, 8', shew one circuit and the dotted
lines t, t, shew a second circuit; to complete the circuit s, s', the end 1 of S should
be in metallic contact with the end 2 of S', and the end 3 of S' with the end 4 of S;
if the end of S be in metallic contact with the end 1 of t, and the end of t with
the end 2 of S', the end 4 of S with the end 4 of t¹ and the end 3 of t¹ with tho
end 3 of S', then 81, t, 8, and t, will make one complete metallic circuit.
In Figure 32 the odd numbered circuits are shewn as connected to the metal
pieces u along the upper edge of the upper surface of the board, and these circuits
are completed from top to bottom of the upper surface of the board by metal
connections w between the pieces u, as more fully shewn in perspective in Figure 35.
The even numbered circuits are shewn as connected to the metal pieces y along one
side of the lower surface of the board, and these circuits are completed from side to
side of the lower surface of the board by metal connections between tho said
pieces y, as also shewn in Figure 35.
When the metal connections w and are in the position shewn in Figure 35 each
circuit is complete in itself and neither is connected with any of the others, but if
tho metal connections w and are removed or turned into the position shewn in
Figure 36 at the crossing of any two circuits each of these circuits will be broken,
leaving four ends to each, as illustrated in the diagram, Figure 34, but if the
piece u of Figure 36 bo connected by a metal strip v with the piece y', the piece u²
with the piece y, the piece u³ with the piece 23, and the piece w with the piece y',
then the two circuits shewn in Figure 34 will become one circuit.
It will now be clear that any odd numbered circuit can be connected with any
even numbered circuit by the switch board shown in Figure 32, and also that any
odd numbered circuit can be connected with any other odd numbered circuit shewn

page_text: in that Figure by connecting them both with any even numbored circuit, and also
that any two even numbered circuits can be connected by connecting them both
with any odd numbered circuit.
The metal connecting pieces w, z, are attached to a plug x and are each insulated
from all the others. The up and down connecting picces v are also attached to the
plug and insulated.
When the number of circuits is large and likely to be constantly increased one
set of circuits, those running crosswise, for example, may be mere connecting
circuits, and all the telephone circuits may be parallel with each other on the switch
board; for example, suppose the circuits 2, 4, and so on, be mere connecting circuits,
and the circuits 1, 3, and so on, be the working circuits, then, if it be desired to
connect, say, 1 and 3, the plug at the crossing of 1 and 2 is turned one quarter of a
circle, and so is the plug at the crossing of 2 and 3, and the circuits 1, 2, and 3, arc
thereby brought into one circuit.
The number of connecting circuits will depend upon the number of working
circuits and the frequency with which they are used, for it is not ordinarily
desirable in telephone circuits to connect more than two working circuits. This
arrangement has also the objection that two plugs must be handled to connect any
two circuits.
Figures 37 and 38 shew another form of switch-board by which each circuit is
made to cross all the others, in order that any circuit may be connected with any or
all of the others. Here the plugs aro arranged in the form of a triangle; this
triangle will however be an undesirable shape with a great number of circuits, but
it may readily be made in sections which may be arranged in a desirable shape, as,
for instance, that illustrated by Figure 39, suitable connections being made between
the said sections, as indicated in Figure 37.
By means of this Invention a number of telephones or other electrical instruments
can be used in one circuit each practically independent of the others, for each station
can be called from the central office, and each can call the central office by means too
well known to need description, and if desirable any station can call any other
station in the same circuit.
The aforesaid secret system by which the telephone or other electrical instrument
is cut out of the circuit until the calling instrument is properly set to bring it in
is a feature which has long been desired for telephone service, and which is
applicable in many other cases.
The node herein described of connecting the telephone or other electrical
instrument and the calling instrument with the circuit by means of a switch,
so that one is always out of the circuit while the other is in, is an important
feature of this Invention, as it admits of calling any other station in that circuit
without working the instrument at the station where the telephone is removed
from its holder; it also makes the resistance less than if the circuit were through
both the telephone coils and the instrument coils.
The switch-system is applicable to any number of complete metallic circuits.
Having thus fully described the said Invention as communicated to me by my
foreign correspondents, and the manner of performing the same, I wish it under-
stood that I claim,―
First. The signalling instrument above described having an electro-magnet with
two armatures, both of which are moved by a heavy current while but one of them
is moved by a light current.
Second. The signalling instrument above described with the notched disc and
finger, the disc being revolved by the passage of the current, and the signal
being given only when the notched disc is arrested so that the finger can enter
the notch.
Third. The signalling instruments above described with the pawls and their
wheels and stops for arresting the motion of the said pawls when the said wheels
are in certain positions.
Fourth. A series of signalling instruments and a series of telephones in

page_text: combination with a series of switches, the telephones being switched out of the
circuit when the coils of the signalling instrument are switched in, and tho
coils being switched out when the telephones are switched in, substantially as
above described.
Fifth. The apparatus illustrated in Figures 27 to 31, and consisting in a series
of calling instruments with a series of telephones, each telephone being cut out
of the circuit until its instrument is set for calling.
Sixth. The central switch above described and shewn in Figures 32 to 39.
Seventh. In a signalling instrument for telephones the combination of the
fingers j,, and k, k, the bridge pieces and, the hook ³, and the contact-
point, arranged in combination with the main and local circuits, substantially as
above described.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twenty-ninth day of September, in the year of our Lord
One thousand eight hundred and eighty.
DODT TATZE
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