Improvements in Automatic Telephone and other Electric Exchanges.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Automatic Telephone and other Electric
Exchanges.
A communication by ALMON B. STROWGER, of the City of Chicago, in the
County of Cook and State of Illinois, United States of America.
I, GEORGE CECIL DYMOND, M. Inst. M.E., of the Agency for Foreign
Patent Solicitors 6 Lord Street, Liverpool aud 6 Bank Street, Manchester
both in the County of Lancaster and 323 High Holborn in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
This invention relates to means for switching a telephone, telegraph or any other
electrical instrument into electrical connection with any other electrical instrument
of a given system, as will be hereinafter explained. The particular object is to
provide means whereby a person at one station may make connection with any other
station in the system by the aid of electrical appliances, without the assistance of
an operator at the central station, and a further object is to provide means for the
purpose of a very reliable nature so as to adapt this system of exchange to
general use.
In describing this new system of exchange, it will be confined to its application
for telephonic purposes, but it can be applied equally well to changing the electrical
connections for telegraph and other similar instruments, dynamos or any kind of
electrical appliances where changes in connection are made from a distant station.
For the purpose of illustration, the place where each telephone is located will be
termed a substation, and the exchange mechanism, located at some distance from
the telephone, the central station. The substations are each connected with the
central station by means of two wires in the herein described system of mechanism,
one of the wires serving for telephonic and the other for switching purposes. At
the substation, in addition to the telephone, there are keys serving to control
currents of electricity which operate the mechanism at the central station. For
the sake of brevity, the system at the central station, which can be operated by a
person at a substation, will be termed an exchange."
66
At the central station, there are as many exchanges as there are telephones or
substations, so that each telephone is intimately connected to a particular exchange,
by means of the two wires above mentioned, which exchange cannot be operated
from any other telephone, but each exchange is connected electrically with every
other exchange at the central station for telephonic purposes.
The new system of electrical exchange is illustrated in the accompanying
drawings, in which :-
Figure 1 is a front elevation of the operative mechanism with the switch table
and part of the top of the base shown in vertical section.
Figure 2 is a side elevation at a right angle to Figure 1 of the mechanism
directly connected to the main spindle, the switch table being in vertical section.
Figure 3 shows three views of the main spindle, the last view at the right having
a portion of the top and bottom ends broken away to show longitudinal and
transverse holes.
Figure 4 is a side elevation of a fuse which is secured to the main spindle.
Figure 5 is a plan view of Figure 4.
Figure 6 shows a thrust rod which operates within the main spindle, as will be
described.
Figure 7 is a plan view of the switch table together with several other parts, the
top of the base broken away.

page_text: Figure is a portion or the switch table and base of the instrument showing a
means for adjusting the position of the switch table.
Figure 9 is a horizontal section of Figure 1, showing mechanism for rotating
the main spindle in one direction, and which will be fully explained.
Figure 10 is a partial view of central portion of Figure 9 showing method of
withholding pawls from ratchet wheels.
Figure 11 is a view similar to Figure 10, but showing combined ratchet wheel,
pawl and stop in action.
Figure 12 shows respectively side and top views of spring arm for main spindle,
one of which arms supports contact head shown in Figure 13, respectively in side
and end views.
Figure 14 elbow lever for actuating contact head';
Figure 15 section of step and lower end of hollow portion of main spindle, showing
ball bearing;
Figure 16 respectively elevation and vertical section of step bearing for lower
end of spindle ;
Figure 17 respectively top, side and end views of adjustable stop for main
spindle;
Figure 18 respectively side and plan views of combined pawl and armature, the
pawl for engaging with the teeth of the main ratchet wheel, and serving as a back
stop for the main spindle;
Figure 19 respectively side and plan views of bifurcated lever, and armature for
imparting a longitudinal motion to the main spindle ;
Figure 20 is respectively a side and front elevation of an auxiliary switch dial
detached from Figure 1 to show the method of wiring.
Figure 21 is, respectively, a front and side elevation of the switch arm and
ratchet wheel which revolve before the dial shown in Figures 1 and 20.
In Sheet 4, Figures 22 and 23, and 26 and 27 are, respectively, telephones and
switches for two separate substations.
Figures 24 and 25 are exchanges at the central station, which are electrically
connected to the substations above mentioned, being one exchange for each of the
two substations.
Similar figures and letters refer to like parts throughout the several views.
1 is the base upon which most of the operative parts composing the central exchange
are mounted. 2 is the top of the base which has a position at a right angle to
Figure 1. Figures 2, 9, 10 and 11 show a portion 21 of top which hangs down
from the front edge of the top, but is broken away in Figure 1 in order to show
the operative mechanism attached to the upper portions of base 1. One of the
most important parts of the central exchange is the switch table 3 which, in this
instance, consists of an annular shaped piece of insulating material having a neck 4
which elevates the table above top 2 of the base 1. The switch table is adjustably
attached to top 2. Around the switch table, Figure 2, are annular rows of wires 5,
whose heads project through table 3, as shown, a portion of each row indicated by
dotted lines, the lower ends of the wires projecting outward from under the
projecting outer portions of table 3, to a sufficient distance to permit an easy
attachment to them of certain wires, which will be described. Centrally located
at the centre of the diameter of the circular rows of wire heads 5 is the main
spindle 6, whose lower end has a pivotal ball bearing in step 7, which step is
supported by means of a projecting lug 8 from base 1. The upper end of spindle 6
is pivoted upon the lower end of the screw binder 9, which screw is held in central
position by means of the cross brace 10, the feet of the brace being secured to the
switch table 3 near the outer edge thereof. Main spindle 6 is pivoted so as to be
capable of a small amount of longitudinal motion, which will be again referred
to. Near the top of the main spindle are secured to a central boss, spring
arms 11 and 12. Constructed to slide upon arm 12 is contact head 14, which is
provided with a contact point 15 and an arm 16 to connect the head with the
long arm 17 of an elbow lever, which lever is pivoted to a projecting lug 19

page_text: of main spindle 6. The short arm 20 of the elbow lever projects inward, and
its end is pivotally connected with the top. of a short pitman 18, the lower end
of the pitman being pivotally connected to the top of thrust rod 21, which rod
passes down through the centre and out at the lower end of main spindle 6, where
the lower end of rod 21 is pivoted in the top of a short piece of cog rack 22, to permit
rod 21 to rotate. This rack 22 is fitted to slide vertically in side and rear guide 23.
There is a screw 24 under the end of rack 22, as shown, by means of which the
distance of the downward movement of the rack 22 can be adjusted, the rack being
always urged downward by the action of spring 25, at arms 11 and 12, pulling
radially inward upon contact head 14, which, by the connection of the elbow
lever 17-20 the short arm 20 of this lever presses downward against thrust rod 21.
It will be noticed that spring 25 passes directly through spindle 6.
The construction of step 7 is shown in section, Figures 15 and 16, the centre of
the step being perforated at 26 to permit the passage of thrust rod 21 downward
from spindle 6. At 6' are balls fitted under the lower end of spindle 6 to diminish
friction. Projections 27 at the bottom of step 7 are loosely fitted to holes in the
projecting lug 8, so as to prevent the step from rotation with spindle 6, but permit
the step and spindle to be moved vertically a short distance. The lugs 27 project
helow the lower side of lug 8, and bearing against their lower ends are the
ends of the bifurcated lever 28, Figures 1 and 19, which lever is pivoted at the
centre of its length to a lug, which lug is firmly secured to base 1, and forms a part
of the guide 23 of rack 22.
There is an armature 29 attached to the outer end of lever 28, and below and
attached to an outwardly projecting bracket 30 from base 1 to an electrical
magnet 31, by which armature 29 and lever 28 are operated. At 32, Figures 1,
2, 9, 10 and 11, is a ratchet wheel having over one hundred teeth, and at 33 is
a lever which is pivoted at 33, the lever having a pawl 34 at the outer end of its
long arm to engage the teeth of wheel 32. An electro-magnet 35 is secured to
the base 1, and the armature 36 of this magnet is secured to lever 33.
Lever 33,
Figure 9, has a screw stop 36¹ to limit its motion. At 38 is a ratchet wheel
having one tooth to every ten teeth on ratchet wheel 32, and a lever pivoted
at 40, which lever has a pawl 43 at the end of its long arm contacting with the
teeth of and for operating ratchet wheel 38, and there is an electro-magnet 41,
having an armature 42 which is attached to lever 39. Secured to ratchet
wheel 32 is a pin 321 which operates as a stop by contacting an arm 44 of an
adjustable slide 45, this slide being movably secured to the front of base 1.
Figures 1 and 9 show a magnet 46, which is attached to base 47, the base
having an arm 48, to whose top end is pivotally secured the combined pawl and
armature 491, Figure 18, this armature being operated by a magnet 46, and the
pawl engaging with the teeth of ratchet wheel 32, serving as a stop, which stop
is released from contact with the teeth of wheel 32 by the attraction of magnet 46
for armature 49¹, as will be further explained. The base 47, together with all
the attached parts, is adjustable in order that the contact end of pawl 49 can
be moved to stop ratchet wheel 33 and all parts attached to spindle 6 in the
exact position necessary. Screws 50 and 51 are operated to adjust pawl 49 to the
proper position.
In Figures 1 and 2 is seen a ratchet wheel 52, which is pivoted to revolve
on a stationary pin 53, the pin having one end firmly secured in the end of
lug 53 of base 1. In Figure 2, firmly secured to the front side of ratchet
wheel 52, and revolving therewith, is seen a small pinion 54 which engages with
the cogs of rack 22. There is an electro-magnet 55 secured to a bracket 56 of
base 1. The armature 57 of magnet 55 forms one piece with pawl 58, and is
pivoted at 59 to a projecting lug 60 of base 1. Pawl 58 is held in contact
with ratchet wheel 52 by springs 61, and the pawl is released from contact with
the ratchet wheel by the attraction of magnet 55 for armature 57. Ratchet
wheel 52 is revolved by the action of magnet 62 attracting armature 63 of
lever 64, which lever is pivoted at 65. At the end of 64 there is pivoted a

page_text: pawl 66 which engages the teeth of ratchet wheel 52, and the length of the
lever is such that one downward stroke causes pawl 66 to revolve wheel 52 a
distance equal to the pitch of one tooth thereof. Pawl 66 is always out of
engagement with ratchet wheel, 52, when lever 64 is at the upward limit of its
stroke, by a small forward projection 67 of the pawl striking against adjusting
screw 68, for the purpose as will appear hereafter. There is a screw 69 which
passes through a stationary lug 70, and this screw holds pawl 66 in close engage-
ment with the teeth of ratchet wheel 52, when the pawl is at the termination of its
downward stroke, which combination of parts serves as stop mechanism to limit
ratchet wheel 52 from turning more than one notch for every downward stroke
of lever 64. 71, Figures 1, 2, 4 and 5, is a fusee, which is firmly secured to main
spindle 6. To the fusee 71 is attached one end of a chain 72, the other end of the
chain being attached to a spring 73. This fusee, chain and spring mechanism are
for revolving shaft 6 against the action of pawls 34 and 43, the fusee equalising the
pull of 73.
At 77 and 78 are wires which carry currents of electricity from the substations
to the several magnets which operate the mechanism of the exchange at the central
station, Figure 1. Wire 77 is attached to a stud pin 79, which pin is secured to the
dial 80, Figures 1 and 20, this dial being firmly secured to the base 1 of the
exchange. Around the face of dial 80 are the contact heads 80, the heads on
opposite sides being connected electrically, as shown in Figure 20, thus forming
pairs, each pair of contact heads being insulated from the other pairs of contact
heads of dial 80. There is a ratchet wheel 82, Figures 1 and 21, which has a
bearing upon and is capable of revolving around stud pin 79. Attached to ratchet
wheel 82 is a spring switch arm 83, which arm is carried around the face of dial 80,
the outer end of arm 83 being capable, in its revolution, of contacting successively
and separately each of the contact heads 80' of dial 80. There is an electro-
magnet 84, and an electric current is communicated to this magnet over wire 78,
the out current wire of magnet 84 being connected with the ground by a wire to
ground screw binder 85. A lever 86 has an armature 87 attached thereto, which
armature is attracted by the core of magnet 84 and operating lever 86, whose
pawl 88 contacts with ratchet wheel 82, one downward thrust of pawl 88 being so
adjusted as to revolve ratchet wheel 82 equal to the pitch of one tooth, which, in
this instance, is one-tenth of a revolution, so that, at each time, one unbroken
current of electricity is sent over wire 78 through the coils of magnet 84, switch
arm 83 is moved forward one-tenth of the circle of dial 80, and so on, each clectric
impulse in magnet 84 causing switch arm 83 to contact the next succeeding contact
head 80. Now, connected directly with five pairs of contact heads 80', at one side
of dial 80, are wires R. Tel. U. T. and H., which letters signify, respectively,
Release," "Telephone," "Units," "Tens" and "Hundreds."
66
These wires form electrical communication as follows:-
Wire R connects the dial 80 with release magnets 46 and 55, the same current
of electricity passing through both magnets and operating them simultaneously, and
the same current passing out of magnet 55 through wire R into screw_binder 74,
thence by wire through electro-magnet 31, thence through wire F to screw
binder 75, which is connected with the ground.
Wire Tel. connects dial 80 with screw binder 9 at the top of the exchange,
Figure 1, thence the current of electricity passes to the central spindle 6, spring
arm 12, contact head 14, and out upon one of the wires 5, should the head 14 be
in contact with any of them at the top of the switch table 3.
Wire U connects dial 80 electrically with the units magnet 35, thence by wire U
to screw binder 74, thence by wire F through electro-magnet 31, thence by wire F
to ground screw binder 75.
Wire T connects electric current from dial 80 with electro-magnet 41, thence by
wire T to screw binder 74, thence by wire F to ground screw binder 75.
Wire H electrically connects dial 80 with electro-magnet 62, thence by wire H
to screw binder 74, thence by wire F to ground screw binder 75.

page_text: By this arrangement, the out current wires from magnets 35, 41, 46, 55 and 62
all connect with screw binder 74, thence by wire F through magnet 31, which
magnet is thus always energised by every current of electricity which passes-
through the other magnets shown in Figure 1, for the purpose as will be described.
hereinafter.
The construction and relation of the switch table are shown in Figures 1, 2, 7
and 8. In this instance, it is intended to perforate the table with ten concentric
rows of holes, as shown by dots 5 and dotted lines in Figure 7, each row to have-
one hundred holes, making a total of one thousand holes for the entire table, and
each of these holes is to form the place of attachment of a wire, the ends of
the wires preferably projecting slightly above the top of the table, and the other
end of the wires projecting radially outward all around under the table to a
distance sufficient to be easily connected to other wires of the exchange system..
For convenience; the wires of the first row next the centre of the table will be
numbered from 1 up to 100, and the next row outward to be numbered from
100 to 200, and so on, the last row being 900 to 1000, and any convenient number
of rows
can be added, if necessary, or a greater number of wires than one
hundred can be placed in each of the rows to suit the requirements of practice.
When spindle 6 is in the position shown in Figure 1, with pin 32¹ in contact
with adjustable stop arm 44, the contact point 15 of head 14 will rest upon the
metal plate 81, which is sunk with its upper face flush with the top surface of
switch table 3, Figure 7. In this position, contact head 14 will have no electrical.
connection with wires 5.
For convenience of description, the plate 81 will be termed the "zero plate,"
on switch
since it forms the starting place from which to find any numbered wire
table 3. Spindle 6, with its several attached parts, is held at the start or zero.
position, with pin 32' against the stop arm 44 by the tension of spring 73, whose
attached chain 72 is secured to fusee 71 at its largest diameter, so that, when the
spring is contracted, it will have the advantage of greater leverage to turn spindle 6, .
but, when the spring is pulled out to its greatest length, and its tension greatest,
chain 72 exerts a pull at the smallest diameter of the fusee, the action of the
spring 73 turning arm 12 with head 14 in the direction of arrow G, Figure 7.
When an electric current is sent through magnet 35 by way of wire U, pawl 34
engages ratchet wheel 32, which is turned the distance of the pitch of one tooth,
which revolves spindle 6 and arm 12 with contact head from the zero plate 81 in.
the direction of arrow J, Figure 7, so that point 15 of head 14 will contact the
first wire 5 in the first row next the centre of the switch table, when, if the current
is broken in magnet 35, spring 37, Figure 9, will lift lever 33, pawl 34 falling into
the next higher notch in wheel 32, when, if another current of electricity is sent
through magnet 35, contact head 14 will simultaneously be moved forward with its
contact point 15 resting upon wire No. 2 in the first row, and so on, until, by the
successive impulses by currents sent through magnet 35, the contact head 14 will
be carried around and successively contact the end of every wire in the first row
until the pin 32 will contact the opposite side of stop arm 44, when, if required, the
spindle 6, together with contact head 14, can be quickly revolved backward to
the starting place, or zero plate 81 by sending a current of electricity into
release magnet 46 by wire R, when armature 49¹ will be operated and disengage
its pawl 49 from wheel 32, when spindle 6, being free to revolve, will quickly
return because of the pull of spring 73 and fusee 71 until pin 32¹ contacts with
adjustable stop arm 44, when contact point 15 will again be at the zero plate 81.
In order to facilitate the operation of this exchange, the ratchet wheel 38 has
been introduced, having ten teeth, which wheel is also firmly secured to spindle 6,
and is operated by an electro magnet 41 having an armature 42 attached to a
lever 39, which lever has a pawl 43 to engage the teeth of the ratchet wheel.
Now, it is obvious that, by sending a current through wire T into magnet +1,
spindle 6 would be turned over as much space by one downward thrust of
pawl 43, turning wheel 38 the distance of the pitch of one of its teeth, as would.

page_text: be done by ten separate thrusts of pawl 34 on. wheel 32, so that, should it be
necessary to have contact point 15 connect with wire 4 of the switch table 3,
four separate and distinct currents of electricity are sent through magnet 35,1
when ratchet wheel 32 will be turned through the distance of the pitch of four
teeth, when contact point 15 will rest upon the end of wire 4.
The means have now been explained for causing contact head 14 to move
and contact its point 15 with the end of every wire in the first row of switch
table 3, and the means by which the contact head 14 is carried to the second,
third or other rows of wires exterior to row one, will now be described.
When a current of electricity is sent through magnet 62 over wire H,
armature 63 together with lever 64 and pawl 66 are operated, pawl 66 by the
downward motion of lever 64 moves out of contact with screw 67, and the lower
end of the pawl contacts with the teeth of ratchet wheel 52, and a continued
downward motion of the pawl turns wheel 52 the distance of the pitch of one
tooth thereof, stop pawl 58 has engaged a tooth of wheel 52, so that, when the
current. of electricity ceases in magnet 52, spring 64¹ raises the long arm of
lever 64, together with pawl 66 to the position shown in the drawing, the
projection 67 contacts screw stop 68 and turns the pawl on its pivot and forces-
it out clear of ratchet wheel 52, the ratchet wheel being held in the changed
position by pawl 58. By the partial revolution of wheel 52, rack 22 is caused
to ascend by the action of pinion 54, which is attached to wheel 52, the upward
movement of rack 22 causing the attached thrust rod 21 also to rise, and the
upper end of the thrust rod, being connected to the short arm of elbow lever 20-17,
causes the long arm 20 of this lever, together with the attached contact head 14,
to move outward from the centre of spindle 6 the distance for the point 15 of
head 14 to contact the second row of wire ends of switch table 3. It is under-
stood that this action takes place while the contact head 14 is at zero plate 81.
and before shaft 6 is revolved to carry pin from stop arm 44. It is obvions
that, every time a current is passed through magnet 62, contact head 14 will.
be moved outward from the centre of shaft 6 to the distance of one
row of
wires 5 from the next inner row, and so on to any row in table 3, when any
certain wire in the particular row desired can be contacted by point 15 of head 14,
by the means described for the first row. When it is desired to return contact
head 14 to the zero plate before the first row of wires on switch table 3, a
current of electricity is sent into magnet 46 through wire R, which releases
pawl 49, and the same current, after passing through magnet 46, is led into
magnet 55 by wire R when armature 57 is operated, causing the release of
pawl 58 from ratchet wheel 52; when, by the gravity of rack 22 and thrust
rod 21, and the tension of spring 25 operating to pull contact head 14 and,
arm 17 of elbow lever 17-20 inward and short arm 20 downward with thrust
rod 21, rack 22 falls so that its lower end rests upon the top of adjusting screw 24,
and, in the meantime, pawl 491 being released, shaft 6 is carried round by the
pull of spring 73 on fusee 71 until pin 32¹ contacts with adjustable stop arm 44,
when the point 15 of head 14 will rest on the zero plate 81 before the ends of
the first row of wire heads 5. In the operation of the several parts herein
described, if shaft 6 should have no vertical longitudinal motion, the point 15 of.
contact head 14 would cause considerable friction by its contacting the top of
switch table 3, while arm 12 is being carried around to some designated wire
end 5, or, when the pawls 49¹ and 58 are released and spindle 6 is revolving
backward by the action of spring 73, there would necessarily be required a much
stronger spring 73 to give the necessary power for this duty. Therefore, to
obviate this objection, means are provided to lift head 14 clear of switch table 3,
by connecting the out current wires from magnets 35, 46, 55, 41 and 62 to screw
binder 74, and then screw binder 74 by wire F is connected to ground screw
binder 75, as hereinbefore stated, so that, simultaneously with every horizontal
movement of contact head 14, magnet 31, through the medium of bifurcated
lever 28, lifts step 7 from bracket 8 together with spindle 6, spring arm 12 and
"

page_text: the attached head 14, the distance lifted being small, and, simultaneously with
the action of any of the other magnets, head 14 is moved to any position, when
spindle is moving forward or backward, without point 15 contacting with any
part of switch table 3 or with wires 5, until spindle has ceased revolving, thus
making it possible to construct a switch table 3 with many thousands of wires 5,
any one of which are within easy reach of contact head 14, without requiring more
power to carry contact head around the outer than the inner rows of wires of switch
table 3.
In Figures 9 and 10, it will be noticed that pawls 34 and 43 are always 'lifted
from engagement with the ratchet wheels, when the pawls are not in action, the
ratchet wheels and shaft 6 being held from turning by the action of spring 73 on
fusee 71, wheel 32 operating against pawl 49' which is one of the release pawls.
There is a projection 84¹ near the pivotal centre of both pawls 34 and 43, which
projection contacts with screws 85', which screws pass through a portion of 21 of
top 2. Stop screws 86¹, Figure 9, are also provided, which contact the ends of
these pawls to serve as stops for the ratchet wheels in the same manner as has been
described for pawl 66, which is operated by magnet 62. In order to insure perfect
central contact of contact point 15 with the ends of wires 5 on switch table 3, this
switch table is secured to the top 2 of the base I so that it can be moved slightly
concentric with shaft 6. Figures 2 and 8 show a lug which projects from the neck 4
of the switch table, and at either side are lugs b and c, Figure 8, which are part of
top 2. Adjusting screws d and e of lugs b and c contact at each side of lug a and
serve as means for quickly and accurately adjusting the switch table and of retaining
it securely in the position desired.
Sheet 4 of the drawings shows the wire connections from two substations to a
central station, the central station having two exchanges, one for each substation.
Figures 22 and 23, let it be assumed, make substation No. 12, and Figures 26
and 27 substation No. 531, the number of the station being shown on the telephone
as usual.
Figure 24 is the exchange belonging to telephone 12, and Figure 25 the exchange
for telephone 531.
Figures 23 and 27 show a combination indicating key and switch for controlling
a current of electricity from battery 90. The body of the switch consists of a
dial 91 of some insulating material, into which are secured four metal contact
heads 92, which heads are all connected together electrically by a wire 93. Contact
heads 92 are placed near the outer edge of dial 91. Near the centre of the
dial are five contact heads 94, all connected together by a wire 95, which wire is
electrically connected by wire 78 to an exchange at the central station.
Wire 93,
which connects the outer contact heads 92, is connected electrically by wire 77 to
an exchange at the central station.
The combination key, indicator and switch arm 96 are capable of revolving
around the face of dial 91 like a crank, the arm being pivotally secured to the
centre of dial 91 as shown. In revolving arm 96 around the dial, the arm will
successively and separately contact each of the contact heads 94, but contact
heads 92 will be passed over, since they are not upon the same but a lower plane
than heads 94.
Heads 92 can be contacted by arm 96 by pressing upon the thumb button 97 when
the outer end of arm 96 is directly over one of one of these heads, the arm 96 being
a spring will lift out of contact with heads 92 whenever pressure is released on
thumb button 97. The arm 96 is connected to the electric battery 90 by wire 98,
which wire has its end secured to the pivotal centre of arm 96, thus it will be
understood that arm 96 is always charged with electricity from battery 90 in this
instance. Telephone No. 12, Figure 22, is connected to exchange, Figure 2+, by
wires 99 and 77, and the same is true of the connection of telephone No. 531 with
exchange, Figure 25. At the central exchange, Figure 24 and Figure 25, it will
be noticed that wire 5 from exchange switch table 3, Figure 24, is connected to
wire 77 from telephone No. 531, Figure 26, and also that wire 5' from switch

page_text: table 3 of exchange, Figure 25, is connected with wire 77 from telephone No. 12,
Figure 22.
It is obvious, with these connections as described, that a current of electricity
can pass from telephone 12, over wires 99 and 77, thence by wire 5¹ to switch
table 3 of the exchange, Figure 25, and the same connections are made from
telephone No. 531, Figure 26, with the switch table 3 of exchange, Figure 24, so
that a person at telephone No. 12, by turning contact head 14, Figure 1, of the
exchange, Figure 24, around to wire No. 531 on the switch table, could ring up
telephone No. 531, Figure 26, but, to more particularly explain, should a person at
telephone No. 12, Figure 22, desire to communicate with a person at tele-
phone No. 531, Figure 26, key 96 would be turned in the direction of the arrow
from contact with head R, or release, to contact head H, or hundreds, where an
electric current will pass from battery 90, over wire 98, switch arm 96, contact
head H, wire 78 and through magnet 84 at the central station, Figure 1, which
will cause pawl 88 to turn ratchet wheel 79 one notch and carry arm 83 around
into contact with the top contact head of dial 80, this contact head is connected
across the rear side of the dial with wire H, which wire is connected with the
hundreds magnet 62. If now key arm 96, Figure 23, is turned further around
dial 91, until the end of arm 96 is over contact head H' of the outer row of heads.
and key arm 96 is forced against dial 91 by pressure against finger button 97, the
outer end of key arm 96 will contact with contact head H₁, and a current of
electricity will pass from the key arm into this contact head, thence by dial circuit
wire 93 to and over wire 77 to the central exchange, Figure 1, where the current
passes over switch arm 83, thence by wire H to magnet 62, which will be energised
and operate the hundreds mechanism. Spring arm 96 is pressed against contact
head H four times more, which sets contact head 14 of Figure 1 in the exchange,
Figure 24, out to the beginning of the fifth row of wires of the switch_table 3.
The next number required is three tens, to get which, key arm 96 is turned to pass
⚫over contact head T, centre of dial 91, when, simultaneously, contact switch
arın 83, Figure 1, central station, will move up to and contact the next succeeding
contact head on dial 80, which is connected to wire T, or tens. Switch arm 96 is
now moved around further in the direction of arrow until over contact head T',
when the arm 96 is pressed down three times, causing the main spindle 6 to carry
contact head 14 of Figure 1 around the switch table 3 to wire 30 in the fifth row.
The next number wanted is 1, or one unit, so the key arm 96 is moved as before
when it will pass over the U contact head near the centre of dial 91, and a current
of electricity will operate to set switch arm 83, Figure 1, so as to communicate
current with wire U for the units magnet 35, when the switch arm 96 is instantly
moved to a position over contact head U' at the outer edge of dial 91, when the
switch arm is pressed in contact with this head, the required number 531 is
contacted by the head 14 of Figure 1, key arm 96 is moved still further around
dial 91, contacting head Tel. near the centre of the dial, which causes switch
arm 83, Figure 1, to open electrical communication with wire Tel., or telephone,
which wire is attached to the extreme top of the exchange to screw binder on main
spindle pivot screw 9, thence an electric current can pass into the main spindle 6,
spring arm 12, contact head 14, thence over wire 5 to wire 77' Sheet 4, thence over
wire 991 to telephone 531, Figure 26, whose signal bells can be made to ring and
the telephone operated as ordinarily.
In operating the combined switch and key, Figure 23, one always knows what
wire is in communication with arm 83 at the exchange, Figure 1, at the central
station, since arm 83 moves successively and simultaneously, one space at a time,
with key arm 96, Figure 23, and so key arm 96 always indicates the exact position
of switch arm 83.
In the practical operation of the combined switch key and indicator, Figure 23,
the key arm is stopped only at the HT U, etcetera. The passage of the arm
⚫over the contact heads H. T. etcetera (near the centre of the dial) being sufficient
to transmit current to energise magnet 84 at the exchange, Figure 1, and cause

page_text: switch arm 83 to move to the right contact head for the magnet indicated by the
letters at the edge of dial 91, Figure 23. Sheet 4 shows but two telephones and
two exchanges, but it is obvious that, by the same system of connection, a great
number of telephones would be capable of being thrown into communication
electrically, one with one another, without the assistance of an operator at the
central station. It is also obvious that this system can be applied to other electrical
exchanges than for telephonic purposes, since the size and relation of the operative
parts can be radially changed without altering the general principle of action, as
hereinbefore set forth.
Having now particularly described and ascertained the nature of the said inven- .
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. In an automatic electrical exchange, the combination with wires, of a switch
adapted to be placed into electrical communication with any one of said wires, the
contact point of which switch occupies a different plane when moving, from what
it does when at rest, as substantially set forth.
2. In an automatic electrical exchange, the combination with wires, the ends of
which are arranged in curved rows, of a switch pivotally secured at the axis of
said rows, and adapted to be placed in electrical connection with any one of said:
wires, the contact point of which occupies a different plane when moving from what
it does when at rest, as substantially set forth.
3. In an automatic electrical exchange, the combination with wires, the ends of
which are arranged in the same plane of a switch adapted to be placed in electrical
connection with any one of said wires, the contact point of which switch
occupies a different plane when moving from what it does when at rest, as sub-
stantially set forth.
4. In an automatic electrical exchange, the combination with wires, the ends of
which are arranged in a horizontal plane, of a switch adapted to be placed in
electrical connection with any one of said wires, the contact point of which is
capable of contacting the ends of the wires when at rest, substantially as set forth.
5. In an automatic electrical exchange, the combination with wires, the ends of
which are arranged in concentric rows in a horizontal plane, of a switch movably
secured at the axis of said rows, the contact point of which switch is movable
radially and concentrically relatively to the axis of the rows of wires, and occupies
a plane above the ends of the wires when moving and occupies the same plane of
the wires when at rest, as substantially set forth.
6. In an automatic electrical exchange, the combination with a series of wires, of
a switch adapted to be placed in electrical connection with any of the wires
aforesaid, and an adjustable stop for limiting the return movement of said switch
after said connection has been made and broken, as substantially set forth.
7. In an automatic electrical exchange, the combination with a series of wires,
the ends of which are arranged in concentric rows or circles, of a shaft journaled at
the axis of the rows of wires, a switch secured thereto, the contact point of which
is movable radially and concentrically to the axis of the said shaft, a rod movable
longitudinally to the axis of the shaft connected with the contact point of the said
switch, and an adjustable stop at the end of the rod for limiting the return
movement of the contact point, substantially as set forth.
8. In an automatic electrical exchange, the combination with a series of wires, of
a switch adapted to be placed in electrical connection with any one of said wires,
the contact point of which switch occupies a different plane when moving from
what it does when at rest, a series of magnets one of which operates the mechanism
for moving the contact point from one plane to the other and the remaining
magnets operate mechanism for moving the point in the different planes. All of
said magnets have a common ground wire, whereby the contact point is always
moved from one plane to the other whenever the switch is operated, substantially
as set forth.

page_text: 9. In an automatic electrical exchange, the combination with a series of wires,
the ends of which are arranged in concentric rows or circles, of a switch movably
secured at the centre of said rows, the contact point of which is movable radially
and concentrically relatively to the axis of said rows, ratchet wheels for placing
said switch in contact with any one of the ends of said wires, an electrically operated
lever for each wheel, one end of which lever is provided with a pawl and means for
positively dis-connecting said pawl from its ratchet wheel when at rest, substantially
as set forth.
10. In an automatic electrical exchange, the combination with a series of wires,
the ends of which are arranged in concentric rows or circles, of a switch movably
secured at the centre of said rows, the contact point of which is movable radially
and concentrically relatively to the axis of said rows, ratchet wheel for placing
said switch in contact with any one of the ends of said wires, an electrically
operated lever for each wheel, one of which levers is provided with a pawl and
adjustable mechanism for disconnecting said pawl from its ratchet wheel when at
rest substantially as set forth.
11. In an automatic electrical exchange, the combination with a series of wires,
the ends of which are arranged in concentric rows or circles, of a switch movably
secured at the centre of said rows, the contact point of which switch is movable
radially and concentrically relatively to the axis of said rows, ratchet wheels for
placing said switch in contact with any one of the said wires, an electrically
operated lever for each wheel, one end of which lever is provided with a pawl, and
means for limiting the forward movement of said pawl and for forcing it toward the
ratchet wheel, whereby it acts as a stop for the ratchet wheel at the end of the
thrust or forward movement of the pawl, substantially as set forth.
12. In an automatic electrical exchange, the combination with wires the ends of
which are arranged in concentric rows or circles, of a switch movably secured at
the centre of said rows, the contact point of which is movable radially and
concentrically relatively to the axis of said rows, ratchet wheels for placing said
switch in contact with any one of the ends of said wires, an electrically operated
lever for each wheel, one end of which lever is provided with a pawl and adjustable
mechanism for limiting the forward movement of said pawl, substantially as set
forth.
13. In an automatic electrical exchange, the combination with an insulated table
having a series of wires secured thereto, of a zero plate insulatingly secured to said
table, and a switch the contact point of which rests upon and is movable toward
and from said plate, substantially as set forth.
14. In an automatic electrical exchange, the combination with an insulated table
having a series of wires secured thereto, of a switch the contact point of which is
adapted to be placed in electrical connection with any one of said wires, said table
being concentrically adjustable relatively to the switch, substantially as set forth.
15. In an automatic electrical exchange, the combination with a series of wires,
the ends of which are arranged in concentric rows or circles, of a shaft journaled at
the centre of said rows, a switch secured to said shaft, means electrically actuated
for rotating the shaft in one direction, a fusee on the said shaft for rotating the shaft
in the opposite direction, and a spring actuated chain secured to and adapted to run
on and off said fusee substantially in a line with angle of the pitch of the spire of
the said fusee, substantially as set forth.
16. In an automatic electric exchange, the combination with a series of wires, the
ends of which are arranged in concentric rows or circles, of a shaft journaled at the
axis of the rows, a switch secured to said shaft, the contact point of which is adapted
to be placed in electrical connection with any one of said wires, means for rotating
said shaft in one direction, and an adjustable stop for limiting the movement of the
shaft in the opposite direction, substantially as set forth.
17. In an automatic electrical exchange, the combination of a base, a switch
table secured thereto, a series of wires insulatingly secured to the table, an arm
movable over the table, a contact head in said arm the point of which is adapted to

page_text: be placed in connection with any one of the wires, and means for moving the arm
and the head, and establishing electrical communication with said wires, substantially
as set forth.
18. In an automatic electrical exchange, the combination of a base, a switch
table secured thereto, a series of wires insulatingly secured to the table in
concentric circles, an arm pivotally secured to the centre of said rows, a contact
head on the arm, the point of which is adapted to be placed in electrical com-
munication with any one of said wires, a lever for moving the head upon the arm,
and means for swinging the arm upon its pivot and for operating the lever, sub-
stantially as set forth.
19. In an automatic electrical exchange, the combination with a base, of an
annular table secured thereto, a series of wires secured to the table in concentric
circles, a longitudinally movable shaft journaled at the centre of the said rows, an
arm secured to said shaft, a contact head movably mounted on the arm, and means
for rotating the shaft on its axis, and for moving it longitudinally, and for moving
the head upon the arm, substantially as set forth.
20. In an automatic electrical exchange, the combination with the base of an
annular table secured thereto, a series of wires secured to the table in concentric
rows, a longitudinally movable shaft journaled at the centre of said rows, the lower
part of which is hollow, an arm secured to the shaft, a contact head movably
mounted on the arm, a rod within the lower end of the shaft, and means for
connecting the head and the rod, and for rotating the shaft and moving it longi-
tudinally, as substantially set forth.
21. In an automatic electrical exchange, the combination with a base of an
annular table secured thereto, a series of wires secured to the table in concentric
rows, a longitudinally movable shaft journaled at the centre of the said rows, the
lower end of which is hollow, and the upper end is perforated, two arms secured to
said shaft, a contact head movably mounted on one arm, a spring through the
perforation of the shaft, one end of which is secured to the head upon the one arm,
and the other end is secured to the other arm, and mechanism for rotating the
shaft and for moving the shaft and the rod longitudinally, substantially as set
forth.
22. In an automatic electrical exchange, the combination with a base of an
annular table secured thereto, a series of wires secured to the table in concentric
rows, a longitudinally movable shaft journaled at the centre of said rows, the lower
end of which is hollow, the upper end is perforated, and the intermediate portion is
provided with a laterally projecting lug, two arms secured to the shaft, a contact
head on one of the arms, a spring through the perforation of the shaft, one end of which
is connected with the head and the other one with the other arm, a longitudinally
movable rod within the lower end of the shaft, an elbow lever on the lug, one arm
of which is connected with the head, and the other arm with the rod, and means for
rotating the shaft and for moving it and the rod longitudinally, substantially as set
forth.
23. In an automatic electrical exchange, the combination with a base of a table
secured thereto, a series of wires secured to the table in concentric rows, a shaft
journaled at the centre of the rows, the upper end of which is provided with a
switch, a ratchet wheel secured to the lower portion of the shaft provided with a
stop, a plate adjustably secured to the base and provided with a stop arm, and
actuating pawl for rotating the shaft in one direction, and means for rotating it in
the other direction and for operating the switch, substantially as set forth.
24. In an automatic electrical exchange, the combination with a base of a table
secured thereto, a series of wires secured to the table in concentric rows, a shaft
journaled at the centre of the rows, the upper end of which is provided with a
switch, a ratchet wheel at the lower portion, a stop on the wheel, a slotted plate
adjustably secured to the base provided with a stop arm, an electrically operated
pawl for engaging with the ratchet wheel, and means for rotating the shaft and
operating the switch, substantially as set forth.

page_text: 25. In an automatic electrical exchange, the combination with the base of a table
secured thereto, a series of wires in the table in concentric rows, a shaft journaled
at the centre of the rows, the upper end of which is provided with a switch, a
bracket. secured to the base, a lever pivotally secured to the bracket, one end of
which supports the lever end of the shaft, and the other end is provided with an
armature and magnet for operating said lever, and means for rotating the shaft and
the switch, substantially as set forth.
26. In an automatic electrical exchange, the combination with a base of a table
secured thereto, a series of wires in the table in concentric rows, a shaft journaled
at the centre of said rows, the upper end of which is provided with a switch and
the lower end is hollow, a rod in the hollow of the shaft, the upper end of
which is connected with the switch, and the lower end is provided with a rack,
mechanism for engaging with the rack and for rotating the shaft, substantially as
set forth.
27. In an automatic electric exchange, the combination with a base of a table
secured thereto, a series of wires in the table in concentric rows, a shaft journaled
at the centre of the rows, the upper end of which is provided with a switch and the
lower end is hollow, a rod in the hollow of the shaft, the upper end of which is
connected with the switch and the lower end is provided with a rack, a pin
adjacent thereto, a ratchet wheel on the pin, a pinion secured to the wheel and
engaging with the rack, an operating pawl for engaging with the ratchet wheel, and
means for operating the shaft and switch substantially as described.
28. In an automatic electrical exchange the combination with a base of a table
secured thereto, a series of wires secured to the table in concentric rows, a shaft
journaled at the centre of the rows, the upper end of which is provided with a
switch and the lower portion is provided with a large and small ratchet wheel and a
spiral pulley, one tooth of the small wheel being equal to ten of the large wheels,
operating pawls for engaging with the ratchet wheels, and a spiral spring attached
to the spiral pulley for returning the shaft to its original position, substantially as
set forth and described.
Dated this 17th day of June 1800
WM. P. THOMPSON & Co.,
Agents for the Applicant.