Year: 1896

page_text: Date of Application, 18th June, 1896-Accepted, 30th Jan. 1897

page_text: guide boxes are adapted to receive therein the clamp-screws 6 that impinge
against, the extension core-plates 3, and provide means for holding the electro-
magnets properly adjusted with relation to the other parts of the switchboard as
will be readily understood. The main cores of the electromagnets and the
extension core-plates 3 thereof inclose copper or other suitable conductor-plates 7
which provide for the free transmission of the speaking current from end to end of
the magnet-cores, including the extensions 3, while any two telephones of the
system are connected together, and at one end the conductor-plates 7 of all of the
magnets 2 have connected therewith by means of the branch wires i, one of
the telephone wires j. The telephone-circuit wire j, is connected to one terminal of
the telephone 8 which is used in connection with the switchboard, and the other
terminal of the telephone is connected with the usual ground wire k.
The telephone 8 is of the ordinary construction excepting that the usual call-bell
is omitted, inasmuch as the call-bell for the system is arranged in connection with
the switchboard, as will be more particularly referred to.
Each pair of electromagnets 2 has one terminal thereof connected by the magnet-
wire 1, to one of a pair of spaced contact-plates 9. There is a pair of the spaced
contact-plates 9 for each pair of the magnets 2, and the contact-plates 9 of each
pair are fastened on the parallel supporting strips 10, the opposite ends of which
strips are suitably secured on the short end boards 11, that are arranged at opposite
side edges of the base board 1 and project a distance thereabove in order to support
the strips 10 properly in position above the row of electromagnets 2. The
parallel supporting strips 10 are spaced a sufficient distance apart to provide for
the proper separation of the contact-plates 9 of each pair, and the contact plates 9
directly opposite the plates which have the wire connections I, therewith have
connected therewith the battery wire m, which may be conveniently arranged in
one of a pair of parallel wire grooves 12, formed in the upper side of one of the
supporting strips 10 and the battery wire m leads from its connection with the
several plates 9 at one side of the space 13 between the two strips 10 to the carbon
element of a suitably-arranged working battery 14. The zinc element of the
working battery 14 has connected thereto one terminal of the other battery wire n,
which is also arranged in one of the grooves 12 separate from the wire m, and has
a series of branch-wire connections o, therewith, which branch wire connections o,
lead to the terminals of the several electromagnets 2 opposite the terminals to
which the magnet wires 1, are connected.
Arranged to work in the space 13 between the parallel strips 10, is a series of
push-buttons 15. There is a push-button for each pair of the spaced plates 9 and
said push-buttous are preferably of a tapering or conical shape so as to properly
work in the space between the strips 10. The said push-buttons have attached to
one side thereof one end of leaf-springs 16, the other ends of which are fastened as
at 17, on a cap board or plate 18 which is fitted on one of the strips 10 over the
wire-grooves 12 so as to cover such wire grooves and properly hold the wires in
position therein.
The springs 16 normally hold the push buttons 15 in elevated inoperative
positions, and the said push-buttons have fitted thereto above the strips 10 the
bridge-plates 19 which extend to both sides of the push-buttons so as to bridge
the space 13 between the directly-opposite contact-plates 9 and are adapted to be
forced down in contact with said plates 9 so as to close the circuit over the same
and also through the electromagnets directly below the plates. When the push-
buttons 15 are depressed so as to carry the bridge-plates 19 on to the plates 9 the
opposite ends of the said plates become engaged in the spring-clips 20 that are
fitted on the ends of the plates 9 at the edge of the intermediate space 13 between
the plates and the said spring clips 20 serve to hold the bridge-plates-19 locked-in
contact with the directly-opposite plates 9 until it is desired for the contact to be
broken, at which time a slight pull with the fingers on the push-button will serve
to disengage the bridge-plates 19 from the clips 20.
The push-buttons 15 have fitted to the inner ends thereof a flanged contact-plate 21

page_text: which is adapted to be normally held in contact with a contact-lip 22, formed
at one end of the plates 9 to which the wires 1, are connected so that there
will be a normally-closed circuit through the said plates 9 and the flanged contact-
plates 21 fitted to the inner ends of the push-buttons 15, and the said flanged contact
plates 21 have connected thereto one terminal of the circuit-wire p which will be
more particularly referred to. When one of the buttons 15 is depressed, it is
necessary that the contact of the plate 21 of the next succeeding button be broken,
and to effect this result the buttons 15 are provided at their sides with offstanding
press fingers 23, the press-finger at one side of one push-button overlapping the
adjacent press-finger of the adjacent button. By means of this construction when
one of the push-buttons 15 is depressed the next succeeding push-button will also
be depressed sufficiently far so that the contact-pieces 19 and 21 of such next
succeeding push-button will have no contact at all, and consequently short-circuiting
through the contact-pieces of the next succeeding push-button is impossible when
one of the push-buttons is.in use..
At one side of the short end boards 11 the base board 1 has fitted thereon at
opposite side edges thereof the bearing-boards 24 in which are journaled the
opposite extremities of an oscillating circuit-roller 25. The oscillating circuit-
roller 25 has fitted to one side thereof a series of spaced contact cores or rods 26
which are grouped sufficiently close together to provide for the proper operation
of the switchboard, while at the same time being placed sufficiently far apart to
prevent any electrical connection between the cores. The said contact cores 26
are arranged longitudinally of the roller and extend from end to end thereof, and
the number of said cores correspond to the number of electromagnets on the
switchboard and consequently to the number of push-buttons 15, but by reference
to the drawings it will be observed that one of the cores or the lowermost core on the
circuit-roller is looped at one end, as at 26", to provide two separate parallel core
Each of the
portions, the function of which will be more particularly referred to.
contact cores 26 has connected thereto one terminal of one of the circuit-wires p,
the other terminals of which circuit-wires are connected to the flanged contact
plates 21 on the inner or lower ends of the push-buttons, 15, and for convenience in
understanding the construction it may be stated that the circuit wire p, connected
to the uppermost of the cores 26, is connected to the contact-plate 21 of the first
push button on the switchboard, or in other words, the push-button used in
connection with the electromagnet A and the other succeeding lower contact-
cores 26 are in circuit respectively with each succeeding push-button, as will be
readily understood.
The oscillating circuit-closing roller 25 is provided in the upper side thereof
with a series of inclined pawl notches 28, which pawl-notches are arranged spirally
and are severally disposed directly opposite or in alignment with the electro-
magnets 2. The spirally arranged pawl notches 28 are adapted to receive therein
the pointed extremities of the pawl-arms 29 of the bell crank swinging armatures 30,
which are arranged to play at one side of the electromagnets. The swinging bell
crank armatures 30 are pivotally suspended from the metallic pivot-rod 31, fitted
on the opposite bearing-boards 24 beyond the oscillating circuit-roller 25 and at
their extremities opposite the pawl-arms 29 the said bell-crank armatures 30 are
provided with the widened contact ends 32, that are adapted to be attached against
the adjacent core ends of the electromagnets.
By reason of the spiral arrangement of the pawl-notches 28 and the engagement
of the pawl-arms 29 in such notches it will be noted, by reference to Fig. 3 that
this construction provides for normally holding the armatures of the second, third
and fourth sets of magnets too far away from such magnets to be attracted thereby
and it is therefore necessary in operating the switchboard to successively depress
the push-buttons to bring the armatures operatively adjacent to their magnets, as
will be hereinafter more particularly referred to..
The metallic pivot-rod 31 which supports the series. of swinging bell-crank
armatures 30, has connected thereto. oue terminal of a circuit-wire y, the other

page_text: .
terminal of which wire is connected to the attaching-flange 33 at one side edge of
the heel plate 34 fitted to the lower side of a shifting key 35. The shifting-key 35
is provided at its upper end with a finger-knob 36 and at its lower end with a
stud 37 that is adapted to fit in the openings 38 formed in the slide board 39.
The slide-board 39 is supported for a sliding adjustment on the ways 40 formed at
opposite side edges of the slide opening 41 formed in the base-board 1, and the said
slide-board 39 has fitted on the upper side thereof two or more longitudinal rows of
contact-plates 42 which are perforated directly over the openings 38 in the
board 39 to receive the stud 37 at the lower end of the shifting-key 35. For
convenience in understanding the operation of the switch-board one row of the
contact-plates 42 are additionally lettered a, b, c, d, e, f, g, and h, respectively, and
each of these contact plates has connected therewith one terminal of a main-line
branch wire r, which main line branch wire has electrical connection with every
other switchboard and telephone in the system. It will be understood that the
main line branch wire connected with the plate a, for instance, is used entirely
independent of the main line branch wire connected with the plate b and the other
succeeding plates in the same row, and when it is desired to connect with a
telephone that is not assigned to any of the main-line wires having branch
'connections with the plates a, b, c, etc., the slide board 39 is moved to a position so
as to bring the other row of contact-plates at one side of the circuit roller 25
whereby the shifting-key 35 can be used in connection with this other row of
contact-plates to effect a connection with the particular telephone desired. While
the slide board 39 is illustrated as being provided with two independent rows of
contact-plates for the main line branch wires, it will be understood that this board
may be made sufficiently large to have even three or four rows of the contact-
plates, according to the number of telephones that are employed in the entire
system.
In order that the arrangement of the different main line branch wires r, may be
clearly understood, attention is directed at this point to diagrammatic Fig. 8 of the
drawings. In this figure of the drawings a few of the branch wires, are
illustrated in connection with a few of the switchboards which are simply
diagrammatically indicated.
By reference to Fig. 8 of the drawings it will be observed that every switch-
board has the same number of branch wires r, and these branch wires are connected
with the main-line wires L in the same way. These main-line wires L are
practically the street-wires of the system, and there are as many of these main line
wires as there are branch wires for each switchboard of the system, so that each
contact-plate 42 of each switchboard has an independent branch-wire connection
with a particular main-line wire. For instance, the branch wires, leading from
the "a" contact-plates 42 of every switchboard are connected with one of the
.main-line wires L, the branch wires, leading from the "6" contact-plates 42 of
. every switchboard with another of the main-line wires L, and so on, as may be
clearly seen from the diagrammatic view. Now, while every switchboard has its
branch wires connected with the main-line wires in the same way it is to be
understood that there are, say, four telephones and switchboards assigned for use
in connection with one particular line-wire, and these telephones are assigned
numbers, respectively, 1, 2, 3, and 4, so that a subscriber will know when he is
called up by the number of rings as will be readily understood.
By reason of this particular manner of assigning a specified number of switch-
, boards to a particular main line it is necessary that the shifting-keys.35 of these
switchboards are normally placed on the particular contact-plates baving the
branch wire connections with the said main line, so that in order to call up any of
the telephones on the line referred to any person in the system simply places his
shifting-key on the contact-plate having a branch connection with the said main
wire and the connection is at once made whereby any of the telephones referred to
can be readily called up.
The shifting-key 35 of the switchbcard is adapted to be fitted directly over any

page_text: of the contact-plates 42 so as to place the heel-plate 34 in direct contact with such
plate 42 so as to connect the switchboard with any particular main line and the.
branches of such main line, and the said shifting-key 35 has pivotally supporte-l at.
one side thereof on the pivot 43 the gravity circuit-closing lever 44. The gravity
circuit-closing lever 44 is provided at one end with a widened toe 45 which
normally contacts with the contact-cores 26 on the circuit-roller 25, it of course
being understood that the toe 45 only contacts with one of said cores at a time,
and when the circuit-roller is in its normal position the toe 45 contacts with the
first or uppermost of the cores 26. The circuit-roller is maintained normally in
such a position to provide for the contact of the lever 44 with the uppermost
core 26 by means of the adjustable counterbalance weight 46 adjustably fittel on
the offstanding weight-rod 47 secured at its inner end in the. roller 25 as clearly
iliustrated in the drawings.
The end of the gravity circuit-closing lever 44 opposite the contact-toe 45
has connected thereto one of the bell-circuit wires s, the other of which bel!
circuit wires is connected to the attaching-flange 48 formel at one. edge of
the heel-plate 34 opposite the flange 33 of said heel-plate. The bell-circuit
wires s, are connected to an ordinary electric call-bell 49 suitably fitted on the
base-board 1 at one end thereof and at one side of the slide-opening 41 in which is
fitted the slide-board 39. When a switchboard is not in use the shifting-key 35.
is always placed on the contact-plate 42 having a connection with the main line to
which the particular switchboard is assigned so that the telephone connected with
this switchboard can be called up from any other telephone of the entire system...
Bearing this in mind and the fact that the push-buttons 15 of two opposite switch-
boards are normally elevated with the contact-plates 21 thereof in direct contact
with the plates 9 having the magnet-wire connections 1 therewith, the operation of
two opposite switchboards will be readily understood from diagrammatic Fig. 7
of the drawings, and at this point attention is called to the fact that the term
"opposite" refers to the telephone being called up, and is simply intended to.
designate one switchboard from the other in diagrammatic Fig. 7 of the drawings,
so that the operation of the apparatus will be readily understood.
Assuming that the telephone to be called up is "No. 1" on the main line
connected with the "a" contact-plates 42, it is simply necessary for the person
manipulating the switchboard to shift his key 35 to the "a contact-plate and .to.
depress the push-button 15 for the electromagnet A. When this push-button is.
depressed, the bridge-plate 19 will be carried against the spaced contact-plates 9.
directly therebelow and a circuit will at once be completed through the battery .14
and the electromagnet A over the wires n, o, l, and m which will cause the said.
electromagnet to be energized and attract the adjacent bell-crank armature 30..
The movement of the bell-crank armature against the core of the energized
magnet closes the telephone-circuit through the armature and the core of the
energized magnet or, at least, through the conductor-plate 7 of such magnet..
By reason of the fact that. the spring clips 20 hold the push-button in a
depressed position the magnet A will be maintained energized. so that the
attracted armature will remain in contact with the core of the magnet and in.
this position it will be understood that the telephone-circuit will be completed
through the wires k, j, the pivot-rod 31, the wire 7, the heelplate 34 of the
shifting-key 35, the contact-plate 42 and through the main line branch wire r,.
and main line wire to the opposite switchboard. When the circuit is thus closed
through the telephone of the person manipulating the switchboard, the ordinary
battery of the telephone will be brought into play and the current of this battery
will pass through the .connections described to the opposite switchboard and in.
entering the said opposite switchboard the current passes from 'the main-line
: branch wire 7, to the contact plate 42, through the heel plate 34 touching such.
contact plate, thence through the bell 49, over the wires s, through, the gravity
circuit-closing lever 44, the first or uppermost of the contact cores 26 through the
wire p to the closed.contact connection 21 22, through; the electromagnet A, thence:
.

page_text: through the wires o, w, and t, the latter wire being a ground connection with the
zinc element of the working battery 14 and which provides for a grounding of
the current which passes through the several connections of the switch board for
the telephone that is being called up.
When the ordinary telephone-current passes through the connections of the
switchboard for the telephone being called up in the manner just described, the
electromagnet of this switchboard will be energized so as to attract the adjacent
armature against the core and thereby close the speaking circuit through the said
armature and core, and when the electromagnet of the opposite switchboard has
thus attracted the armature a speaking circuit will be established between the
opposite telephones through the following connections: k, j, 30, 2, r, main line
wire r, q, 30, j, and k.
When cominunication has ceased the person whose switchboard was manipulated
to secure the connection releases the depressed push-button from its fastenings
so that the several parts of the switchboard will assume their proper relative
positions.
When the pish-button for the first electromagnet A is depressed the magnet A
will be energized so as to attract its armature as already described, and this move-
ment of the armature through the medium of the pawl arm 29 working in the first
notch of the roller 25 will cause such roller to partially, rotate, so as to earry the
first or uppermost of the cores 26 out of contact with the toe 45 of the lever: 44
which will then drop into contact with the second core 26 and in this position of
the roller it will be impossible for any other telephone to call up the telephone
which is in use, and it will of course be understood that the circuit-roller 25 of the
switchboard for the telephone being called up will be partially rotated in the same
manner to secure the same result. Now, assuming the telephone to be called up is
No. 3 on a particular main line, the operator will first adjust his key 35 to the
proper plate 42 and depress the push-button for the magnet A which will cause
one ring of the bells of the switchboards normally in circuit with the main
line wire to be used. Then the push-button for the magnets B and C will be
successively depressed so that when the push-button for-the magnet C is depressed
the bell on the switchboards referred to will have rung three times, so that the
person having the No. 3 telephone on the line brought into use will know that his
telephone is being called up. In this successive depression of the push-buttons it
will be noted that the armature for the magnet A will move the roller 25 to a
position which brings the armature for the magnet B operatively adjacent thereto,
and the movement of the armature for the magnet B will move the roller to a
position which brings the armature for the magnet C to an operative position so
that when this latter magnet is energized its armature will be attracted and will
move the circuit roller 25 to a position which brings the lowermost or double
core 26 against the toe 45 of the lever 44, thereby cutting off communication
from any other telephone except No. 3 on the main line, having connection with
the plate 42 on which the shifting-key 35 rests. However, in this successive
depression of the push-button it will also be understood that the magnets of the
opposite switchboard will be successively energized, so that the circuit-roller 25
of this opposite switcbboard will be partially rotated successively by the first three
armatures of the switchboard so that the roller will be brought to a position corre-
sponding to the position of the roller on the switchboard being manipulated to cut
off all communication with other telephones..
The function of looping or doubling the lowermost or double core 26 on the
roller 25 will be found in connection with the depression of the fourth or, last
push-button on the switchboard for the magnet B. When the magnet C is
energized, the roller 25 is rotated to a position which brings the upper branch
. of the looper or doubled core 26 against the toe 45 of the lever 44 and when the
magnet D or the last magnet on the switchboard is energized the roller will move
this upper branch of the core out of contact with the toe of the circuit-closing
lever which will then drop in contact with the lower branch of the looped or double

page_text: core and allow the proper circuit connections to be made with the switchboard for
the last or "No. 4" telephone on a main line, it being understood that if it were
not for the lower branch of the looped or double core the toe 45 of the lever 44
would drop onto the body of the roller and break the circuit connections when the
last push-button was manipulated.
From the foregoing it is thought that the construction, operation and many
advantages of the hereindescribed telephone-switchboard will be readily apparent
to those skilled in the art wi:hout further description, and it will be understood that.
changes in the form, proportion and the minor details of construction may be
resorted to without departing from the principle or sacrificing any of the advantages
of this invention.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a telephone-switchboard, an electro-magnet, the core of which is included
in the circuit of a telephone, the working battery in circuit with the magnet to
energize the same, a circuit-roller having a contact-core in circuit with the working
battery, a movable armature for the magnet having a pawl connection with the
roller to partially rotate the same, a suitably-supported circuit-closing lever normally
resting against the core of the circuit-roller, and the main line branch wire having
a circuit connection with the armature and also with said circuit-closing lever,
substantially as set forth.
2. In a telephone-switchboard an electro-magnet the core of which is included in
the circuit of a telephone, a working battery in circuit with the magnet the zinc
element of said battery having a ground connection, a circuit-closing device
included in the line of the circuit connections for the battery, a circuit-closing
roller having a contact-core circuited with the circuit-closing device, a movable
armature for the magnet having a pawl connection with the roller to partially
rotate the same, a suitably-supported circuit-closing lever normally resting against
the core of the circuit-roller, and a main line branch wire having a circuit con-
nection with the armature and also with the circuit-closing roller, substantially as
set forth.
a
3. In a telephone-switchboard, an electromagnet the core of which is included in
the circuit of a telephone, a working battery circuited with the magnet, the zinc
element of said battery having a ground connection a circuit-closing. device
included in the line of the circuit connections for the battery, circuit-closing
roller having a contact-core in circuit with the circuit-closing device, a movable
armature for the magnet having a pawl connection with the roller to partially
rotate the same, a suitably-supported circuit-closing lever normally resting against
the core of the roller, a call-bell having a circuit connection with said lever, and
the main line branch wire having a circuit connection with the call-bell and also
with the armature, substantially as set forth.
4. In a telephone switchboard, the combination of the baseboard, an electro-
magnet supported on the board, the core of which magnet is included in the
circuit of the telephone, a working battery in circuit with the magnet, a circuit-
closing device included in the line of the circuit connections for the battery a
circuit-closing roller mounted on the baseboard and having a pawl notch, and a
contact-core circuited with the circuit-closing device, a movable armature for the
magnet having a pawl-arm adapted to engage the pawl-notch of the roller, a series
of contact-plates arranged on the baseboard and having main line branch wire
connections therewith, a shifting key adapted to be fitted on any of the contact-
plates and having a metallic heel-plate, a gravity circuit-closing lever mounted on
the shifting-key and normally contacting with the contact-core of the roller, and
a circuit connection between the heel-plate of the key and the armature, and
also between the heelplate and said circuit-closing lever, substantially..as set
forth.

page_text: 5. In a telephone switchboard, the combination of a baseboard, an electro-
magnet supported on the baseboard the core of which is included in the speaking
circuit of a telephone, a pair of spaced contact-plates arranged above the magnet,
a spring-supported push-button arranged to work between the contact-plates and
provided with a bridge-plate adapted to contact with said contact-plates a working
battery, circuit connections between the working battery, said contact-plates, and
the battery, the main line branch wire, and automatically-controlled circuit-closing
connections between the main line branch wire and the core of the magnet,
substantially as set forth.
6. In a telephone switchboard, the combination of a baseboard, a series of
electromagnets supported on the baseboard, the cores of which magnets are
included in the circuit of a telephone, a pair of spaced contact-plates arranged
above each magnet and provided at their adjacent ends with spring-clips, spring
supported push-buttons arranged to work between the contact-plates and provided
with bridge plates adapted to engage in said spring clips, a working battery,
circuit connections between the battery, said contact-plates and the magnet,
the main line branch wire, and automatically-controlled circuit-closing connections
between the main line branch wire and the cores of the magnets, substantially as
-set forth..
7. In a telephone-switchboard, the combination of a baseboard, a series of
electro-magnets supported on the baseboard, the cores of which magnets are
included in the circuit of the telephone, a pair of spaced contact-plates arranged
above each magnet and provided at their adjacent ends with spring-clips, one of
said contact-plates being additionally provided with a contact lip, spring-supported
push buttons arranged to work between the contact-plates and provided with
bridge plates to contact with the former, and with flauged contact-plates adapted
to normally contact with said contact-lips, a working battery, circuit connections
between the battery, contact plates, and the magnets, a circuit-closing roller having
a series of contact cores respectively circuited with the flanged contact-plates of
the several successive push-buttons movable armatures for the magnets having
pawl connections with the roller to partially rotate the same, the main line branch
wire, a suitably-supported circuit closing lever normally resting against the
uppermost core of the circuit-roller, and circuit connections between the main
line branch wire and the armatures, and the circuit-closing lever, substantially as
.set forth.
8. In a telephone switchboard the combination of a baseboard having a series of
guide boxes, a series of electromagnets having flat core extensions adjustably fitted
in the guide boxes and included in the circuit of a telephone, a pair of spaced
contact-plates arranged above each magnet and provided at their adjacent ends
with spring clips, spring supported push-buttons arranged to work between the
contact-plates and provided with bridge-plates adapted to engage in the spring
clips and with offstanding press-fingers which overlap one another, a working
battery, circuit connections between the battery, the contact-plates, and the
magnets, the main line branch wire, and automatically controlled circuit-closing
connections between the main line branch wire and the cores of the magnets,
substantially as set forth.
9. In a telephone switchboard the baseboard, a series of electromagnets
supported on the baseboard, the cores of said magnets being included in the circuit
of a telephone, a working battery in circuit with the magnets, a circuit-closing
device included in the line of the circuit connections for the battery, a weighted
oscillating circuit-roller provided with a series of spirally-arranged pawl notches,
and a series of longitudinal contact-cores corresponding in number to the number
of magnets, and the lower of which cores is looped or doubled, circuit connections
respectively between each core and said circuit-closing device, a series of pivotally-
suspended bell-crank armatures arranged adjacent to each magnet and having
pawl-arms adapted to engage in the pawl notches of the roller, a suitably-
supported circuit-closing lever normally resting against the uppermost core of the

page_text: circuit roller, the main line branch wire, and circuit connections between the main
line branch wire, the armatures and the circuit-closing lever, substantially as set
forth.
10. In a telephone switchboard, the combination of the base-board, a series of
suitably-energized electromagnets, the cores of which are included in the circuit
of a telephone, a weighted circuit roller having a series of contact-cores
respectively in circuit with the several successive magnets, the swinging armatures
having a pawl connection with said roller, a series of contact-plates separated
from each other and having openings therein and main line branch-wire connections
therewith, an adjustable shifting-key provided at its lower end with a stud to engage
the openings of said contact-plate and with a heel-plate to contact with the same, a
gravity circuit-closing lever pivoted at one side of the key and provided at one end
with a toe to contact with the cores of the roller, the call-bell having a circuit
connection with said lever and the heel-plate of the key, and a circuit connection
between said heel-plate and the swinging armatures, substantially as set forth.
11. In a telephone switchboard, the base-board a series of suitably-energized
electromagnets the cores of which are included in the circuit of a telephone, a
weighted circuit-roller provided with a series of contact-cores having suitable
circuit connections with the several successive magnets, the swinging armatures
having pawl connections with the roller, a slide-board adjustably fitted in the base-
board below the roller and provided with separate longitudinal rows of contact-plates
separated from each other and having openings therein and main line branch wire
connections therewith, an adjustable shifting key provided at its lower end with a
heel-plate to contact with said contact-plates, a gravity circuit-closing lever pivoted
at one side of the key and adapted to contact with the cores of the roller, the call-
bell having a circuit connection with the lever and the heel-plate of the key, and a
circuit connection between the heel-plate and the swinging armatures, substantially
as set forth.
Dated this 10th day of rene
BOULT & WADE,
Agents for the Applicants.