Improvements in Systems of Telegraphic or Telephonic Exchanges.
Year: 1894

page_text: Date of Application, 6th Nov., 1894-Accepted, 8th Dec., 1894
COMPLETE SPECIFICATION.
Improvements in Systems of Telegraphic or Telephonic Exchanges.
I, WALLACE CHILDS, of the City of Neosho, County of Newton, State of
Missouri, United States of America, Lawyer, 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 :-
My invention relates to telegraphic, or telephonic exchange systems in which the
subscribers' circuits are all connected with a common "central office," where
connection is made between the subscribers' circuits over which telegraphic, or
telephonic communication is desired to be had, by the subscribers thereto; and the
object of my invention is to provide improved switching means for automatically
making connections between the subscribers' telegraphs, or telephones, and
disconnecting the same without the services of operators or attendants at said
central office.
This object I attain by the mechanism illustrated in the accompanying drawings
in which:
Figure 1 is a plan or top view partly broken away of a switching instrument
containing my invention and adapted to be used in such systems.
Figure 2 is a central longitudinal section on line 2-2 of Figure 1.
Figure 3 is an enlarged side elevation of a part of Figure 2, with a part in cross
section on line a-a and also several of the gear wheels thereat, the use of which
will be shown hereafter.
Figure 4, is a fragment of a cross section on line 4-4 of Figure 1, showing the
travelling electrode switch, means for permitting it to move transversely to the
switch-path and the detail construction of said travelling electrode switch.
Figure 5, is a plan of the bottom plate on which the switch-path is arranged,
showing the circuit wires and the deflecting flanges arranged thereon.
Figures 6, 7 and 8 show preferred forms in which the switch-path may be
arranged on said bottom plate.
Figure 9, is a transverse vertical section on the line 9-9 of Figure 10 of a switch-
operating-instrument containing my invention which is designed to be placed in the
subscribers' office and to be electrically connected with the switching-instrument of
his line at the central office, for operating the travelling switch of the latter.
Figure 10, is a plan partly broken away of said switch-operating-instrument
showing the dials thereon and the hands thereof.
Figure 11, is a diagrammatic view of three switching-instruments and three
switch-operating-instruments connected together in a system of the class mentioned,
and three telephones of ordinary construction to be connected together as shown
hereafter.
Figure 12, shows three fragments in cross section of the bottom plates of three
switching-instruments in the central office and also a wire connecting the same in a
manner comtemplated in this system and for a purpose hereafter shown.
Figure 13, is a perspective view of my switching-instrument.
Figure 14, is a fragmental cross section of my switch-operating-instrument,
showing how the gearing should be arranged to operate the crank reversely to that
shown in Fig. 9 also showing insulation about the gears S s.
The general plan of my improved switching-instrument embraces a spiral or
coiled route for the purpose of giving great length of path or series of paths
within a small area; in such path or paths are arranged contact points of switch
wires for all the subscribers' telegraph, or telephone lines of the system, and in
connection with such switch-path or paths are provided a travelling switch which is

page_text: attached to a revolving arm or support carrying said switch along such path or
paths, the connection of said switch to its support being such as to permit said
switch to move along on the support in a direction transverse to such path or paths
and for keeping, the switch in lateral adjustment therewith.
The general plan of the switch-operating-instrument embraces two contact plates,
each provided with a series of contact points projecting therefrom for making and
breaking electrical connections, one of said plates being adapted to a revolving
pointer for moving and indicating the movement of the travelling switch at the
central office to bring it into connection with the switch-path contact points of the
subscribers' lines which are located within short distances of each other; and
the other of said plates being adapted to another revolving pointer or hand,
which is adapted to be operated as desired in connection with, or independently of
the first named pointer, for moving the travelling switch at the central office to
bring it into connection with the contact points of the subscribers' lines which are
located in the switch path at long distances from each other, and indicating the
amount of such movement.
;
Referring to the drawings, A designates the switch-board constructed of non-
conductive material preferably a hard rubber plate, and A' is the top made of any
suitable material which is supported by the legs B or in any other convenient
manner. The switch-path a of the switch-board is arranged in the form of a spiral
or coil. Over the switch-board and supported by a shaft b is arranged a wheel C
and upon said wheel, is an arm or slotted case support D, upon which is arranged a
travelling switch c. The switch is carried around but always in the same general
direction of the length of the path a, by the rotation of said wheel. The travelling
switch is attached to a slide c' and is thereby rendered capable of longitudinal
movement on the arm D, and it is under the pressure of a spring d tending to move
it outward. The bottom of said travelling switch is provided with a movable stem
and head c² the stem of which is preferably provided with a spring which is
attached to the bottom of the body of c, and to a metal washer, which impinges on
the head and tends to press said head out of the socket of c as shown in
Figures 2 and 4. Over the bottom of the head e² a washer c of non-conductive
substance preferably of hard rubber, is fitted like a collar which is designed to
prevent said head c from presenting a greater contact surface to the circuit wire 7,
than the extended electrode point of said head c² which projects through in the
center of said collar as shown in cross section at the bottom of c² in Figure 4.
The parts and can be omitted if desired and the vertical moving stem
attached rigidly to place; in such case it should be made small enough so that it
would not cover when at rest more than contact point of one wire. The stem
head c² moves against guide flanges F in or alongside of the path or paths a which
are adapted to deflect the head and thereby compress the spring d by moving the
slide c' inward, as the arm moves around against said flange. Said flanges may be
either movable or stationary, or both, if movable they are preferably hinged to the
plate A so as not to go back beyond a perpendicular and are provided with a
slightly turned up corner against which the head c² of the travelling switch
strikes and turns up said flanges temporarily as the switch passes that point and is
deflected by said flanges in its revolutions; the flanges when up operating as guides
for said switch from one coil to that of another coil of the path a.
To the arm D is attached at the side a ratchet G with catch g, on the sliding
piece which engage together and holds the travelling switch against the spring d
until said switch is on the inner coil and past the last flange at F', and is in line
with the return route e-e of said switch, when said catch is carried past the inner
end of the ratchet and will drop down into a vertical position and slide back over
the teeth of the ratchet when the switch passes out over the way e--e and over the
flanges which are normally down thereat and hinged or arranged so as not to
obstruct the outward passage of said switch, until the pawl is carried outward
beyond the end of the ratchet bar G, as shown in Figure 2, so that the inward
compression of the spring d caused by the rotation of the arm D, against the

page_text: flanges F, when released will again bring the catch into working position on the
ratchet.
In Figure 5, F shows the deflecting flange stationary and attached to plate A.
In Figure 6 the path a is depressed in the plate A, at the way e-e which leaves
the flanges separating said depressed portions of the path a, stationary and standing
in same relative position as shown in Figure 5.
In Figure 7 is shown the path a depressed in the plate A, continued its full
length and the part of the flange F at the way e-e made movable to turn up, or
down while other parts of said Hange are continued in rims or stationary flanges.
In Figure 8 is shown the path a depressed as in Figure 7, and the deflecting
flanges or guides stationary and continued around the path a in a series of
standing rims. Also the stem head c³ is shown oblong as I do not limit my
invention to the form shown in Figure 2. It is obvious that the plate A, may be
of the style shown in any one of the Figures 5, 6, 7 and 8 and the construction of all
of the other parts of the switching-instrument be substantially as shown, or that
switching-instruments in a system may use any of said styles exclusively or inter-
changeably as illustrated in said figures.
The wheel C may be operated by electro-mechanism of any ordinary construction;
said mechanism consists in the present instance of an electro-magnet I, armature i
and lever J, the latter being pivoted to the frame and carrying a spring catch or
pawl which rides on the teeth at the periphery of said wheel, in such manner as
to propel said wheel by means of electrical pulsations of said electro-magnet. A
spring K operates to retract the lever and pawl in the usual manner. A pawl L
is arranged in any suitable manner to act as a brake and to hold said wheel from
moving backward. The mechanism as thus applied at the periphery of said wheel
is adapted to move the same forward according as the stroke of the lever is
regulated by the set screws y-y, one tooth or more at each pulsation of the
electro magnet I. Similar operating mechanism is also provided, located at M to
be applied to the shaft b of said wheel m, said gear wheel working in a bracket
attached to the under side of the top A¹ shown by dotted lines at mº in Figure 2,
and worked by a lever and pawl (shown in Figure 13, and similar to lever and
pawl J,,) connected with the electro-magnets at M, and adapted to operate the said
gear wheel m and work it in a like manner and for a like purpose that the wheel C
is worked, shown in perspective in Figure 13. Fitted loosely on the shaft b is a
smaller gear wheel m² with slanting radial grooves on its face, and adapted when it
is revolved, to engage with the spurs of the wheel m¹ which is rigidly attached to
said shaft b, or said wheel m² may engage as desired with shaft direct in any
suitable manner. Figure 3 shows the face sides of m² and m² and their relation
to each other on the shaft bon a line a-a in said figure. The shaft b when
rotated by the wheel C turns in m² but does not communicate any motion thereto,
or engage the spurs of m¹ with said m². The gear wheels m and m' engage
when operated and are of such construction that each electrical pulsation of the
electro-magnets M will cause the wheel C to move through the same distance as
would twenty-five pulsations of the electro-magnets at 1, operating on said wheel C
at its periphery. The gearing may be arranged in same manner but in proper
proportions and operate as fifty or one hundred to one. In the present instance
it is as stated twenty-five to one. By means of the mechanism described at
electro-magnets I, the wheel C is operated for moving the switch e through short
distances as within twenty-five points, and by means of the mechanism at M,
through longer distances as more than twenty-five points and the switch c is made
to travel more rapidly than in the first instance.
The switching-instruments of the systems are connected together in a central
office shown in Figure 11, by as many switch wires or circuits as there are
switching instruments in the system; said wires are designated by the Figure 7,
one wire being adapted to each instrument, and it starts from the switch path
thereof, having one or more contact points exposed thereat to a travelling switch c
as shown on the right side of the switch board in Figure 2, thence it runs to and

page_text: connects with all the switch boards of the switching-instruments of the system
leaving exposed a contact point in each switch-board in the path of each travelling
switch in a manuer as shown on the left side in Figure 2. A view of a manner of
securing said wire 7 is shown in Figure 12. Said wire is passed into an opening
in the switch-board A and secured by a wedge piece or in a suitable manner, and
the wire then drawn taut when it will be secured in the opening and leave the
piece projecting; the covering or insulating thereat of said wire should be removed,
so as to make a contact for the travelling switch. It will be observed that one
single wire connects all, the switch-boards together and may be used by all, but
to facilitate exchanges between subscribers a single wire is assigned to the special
use of each switching-instrument.
The object of having more than one contact point on the same wire in some one
of the switching instruments preferably the one from which it starts, is that more
than one place in the switch-path a may be had by each subscriber where he may
normally rest his travelling switch and be in position for "call" without moving
his switch over the entire route as would be the case were he compelled to move
said switch around the pathway to the initial point of starting.
The mechanism of the switch-operating-instrument in the subscribers' office for
producing the electrical pulsations in the switching instrument at the central office
is illustrated in Figures 9 and 10, in which O designates the box or frame, O' is
a cap bearing for the shaft o, said shaft being journalled in said frame and provided
with two hands or electrode pointers P, p. Q is a shaft provided with a crank
for operating the same. A pawl and ratchet wheel Q₁ are provided to prevent
turning said shaft backward. The shaft Q is geared with shaft o and a large
wheel R (placed loosely on the shaft o), to which the pointer p is connected, by a
small wheel r on shaft Q; and also pinions S, s. The pinion S slides on the
shaft o but will not turn thereon as the shaft may be flattened on one side and the
pinion S correspondingly made to fit it or arranged in any suitable manner for
this purpose, and is held normally against the pinion s by a spring T; the pinion s
should be insulated where it is fitted to its shaft Q, as should all other conductors
where contact is not desired.
The operation of the crank g communicates movement to the pointers P, p;
said pointers moving at different rates of speed for a purpose hereinafter explained.
A levert is provided whereby the pinion S may be thrown and held out of gear
with the shaft for the purpose of keeping the pointer P which is attached to
the shaft o, at rest while the pointer p is in operation. Said lever is also used
for another purpose hereinafter explained. Said pointer P operates in connection
with a serrated conductive dial U which is in circuit with the wire 1 which
connects with the electro-magnet I of the switching instrument in the central office
for operating the lever J in the manner before described. And the pointer p
operates in connection with another serrated conductive dial u which is in circuit
with wire 2 which connects with the electro-magnet M of said switching instrument
in the central office for operating the lever which works the gears at m in the
manner before described..
The circuit formed by the wire 1 is normally closed at and the circuit formed
by the wire 2 is normally open at 3 and the operation of the crank 9 breaks and
closes the circuit I by means of the pointer P coming in contact with the serrated
points ou U thereby producing electrical pulsations in the electro-magnet I, but
produces no effect in the mechanism at M by reason of the break at 3 in the circuit
as stated.
The levert is bifurcated and engages loosely with S whereby said gears Ss are
thrown in, or out of connection, (or constructed in any suitable manner,) also
operating as a switch for alternately breaking and closing the circuits 1 and 2.
For this latter purpose said switch t is provided with a contact plate at v which is
attached to said levert (but insulated therefrom) in any suitable manner; said
plate is adapted alternately to break and close said circuits at 3 and v when said
lever is vibrated for throwing the gearing Ss in, and out of connection. The

page_text: C
serrated contact points on the dials U u are in the proportion of twenty on u
to twenty-five on U in the present instance. Any other proportion may be had
by proportioning properly the operating gearing. The dial U is indexed whereby
the pulsations produced on the points U may be read by noting the position of
the pointer P on said dial which will correspond to the number of pulsations
produced in the electro-magnet I, of the switching-instrument and determine the
distance, or number of contacts made by the travelling switch with the points 7
in the path of a of said switching-instrument. The dial is also indexed counting
twenty-five for each serrated contact point thereon, as each contact thereon by the
pointer p produces a pulsation in the electro magnet M at said switching-
instrument in the central office, equal to twenty-five contacts of the pointer P, in
moving the travelling switch c along the path a to connect with the circuit wires 7
according as said wires are spaced in said path a. Worked in connection with the
pointer p is a small hand which is operated by its gear wheel ¹ which engages
with a spur on the wheel R; said spur turning said hand a half point as
registered on its dial at each complete rotation of said wheel R and its pointer p.
It is obvious then that where the switch boards of a system are constructed of a
size to accommodate twenty-five or less subscribers the hands p and 2 are superfluous;
where over twenty-five and not more than five hundred, z is superfluous, but when
over five hundred and up to ten thousand subscribers the three hands are necessary.
If a system of over ten thousand subscribers be needed the wheel z¹ should be
proportionately arranged to be struck by said spur 2 and the index of z corre-
spondingly numbered. The plate W is preferably of copper or of other suitable
conducting material and of two pieces insulated one from the other and joined
together by a hard rubber ring or other convenient manner. The circuits for the
switching instruments and the switching-operating-instruments are made with
batteries and conductors in electrical connection in the usual manner and it is not
deemed necessary to describe them in detail in order to a full understanding of
my invention. The telephone, or telegraphic instrument shown in Figure 11-is
of ordinary construction and forms no part of my invention except as herein shown
in connection with my invention, and it is therefore not deemed necessary to
describe it more fully.
The circuit connections of the various instruments in the systems are shown in
Figure 11-in which 1 designates the circuit for operation the switching-instrument
through the instrumentality of the mechanism at I, applied to the periphery of the
wheel C; and 2 the circuit for operating the said instrument through the
instrumentality of the mechanism at M applied to the periphery of the wheel m, as
before described, and 4 the telegraph, or telephone main line which runs therefrom
to the central office and connects with the shaft 6, thence with the wheel C, and D,
and travelling switch c in the path a as shown in Figure 2. The electro magnets
and M may be connected in one circuit as indicated by the dotted lines in
subscriber's circuit No. 1. To do this the part of the wire 2 between the
point and the electro magnet M is omitted and the wire 2 joined at as indicated
by the arrow line thereat, and the ground connection severed at at electro
magnet I, and a wire connection made between said magnets as indicated by the
dotted line thereat. In such case the electro magnets I, should be of less
electrical resistance than the electro magnets at M, the battery power should be
normally only sufficient to operate the electro magnet ; and not enough to
operate M. Increased battery power is applied when M is to be worked in this
circuit by switching in the extra battery shown in line 2 at through the contact
plate v. When the circuit 2 is closed at 3 by lifting the levert and bringing its contact
plate at v to cover the broken ends of said 2 as shown in Figure 9, it should be under-
stood that in such case the electro magnet I will be energized also and worked
simultaneously with electro-magnets M but this does not thereby interfere with
the effect desired as the pawl of lever J would ride on the periphery of its wheel C
as lost motion while the lever and pawl of the wheel m of the inagnet M would be
doing work. If two circuits are used the battery may be omitted. The circuit

page_text: for line 2 when operated on but one wire as described would be, starting at ground
on wire 5, then lever V, metal stud v', line 2 through battery to 3, where lever t
should have been raised to cover the points of the wire 2 thereat, and connect
them electrically through the contact plate on said lever t, thence over wire 2
to bracket of shaft Q to Q and thence through r, to R, thence to u and plate W.
thence over wire 2 to, thence on wire 1 through electro magnets I, thence over
dotted line wire to electro magnets M, thence through battery thereat to ground,
the other circuits are readily traceable and it is not deemed necessary to specify
them.
The operation at the subscribers office is as follows, the pointers and the switching-
operating instruments in each subscriber's office are set on the respective dials to
correspond with the position of the travelling switch c on the switching instrument
in the central office, and the relative contact points of all the wires 7 being
indicated by the position of the hands or pointers on said dials of the
plate W, any subscriber desiring connection with any other subscriber of the
system will move the pointers Pp by turning the crank q until said pointers
indicate the desired number, the movement of said pointers over and in contact
with their respective dial points U and u cause electrical pulsations of the electro
magnets and moves the traveling switch c into connection with any line 7 with
which connection is desired in the manner before described; and on whose own
wire 7 the travelling switch c may rest may now be "rung up" in the usual manner
over the main line 4 if the lever t shall first be drawn out so as to move a switch V
from where circuits 1 and 2 come together, (said switch is insulated from said
levert where it is hinged thereto and it is also hinged to a metal bearing fastened
by the side of a wooden block on the frame O, said metal bearing carrying a
ground wire 5 which has connection with said switch V) into contact with the said
wire 4 at v².
In Figure 11 of subscriber's office are shown the several positions of the
pointers Pp, and the corresponding position of the travelling switch c in the
central office.
If subscriber No. 1 moves his crank 9 and turns his pointer P to 2 his travelling
switch c will take the same relative position as is shown in No. 2 and subscriber No. 1
will then be in position to "call or ring up "No. 2 and so with No. 3. If No. 3 should
desire to call No. 1 it would be necessary to have the switch c of said No. 3
travel the entire route or path a until No. 1's wire has reached and said switch c
rested thereon. In case the party to be connected with is within twenty-five points
of the line of the party operating the travelling switch e the connection will be
made by means of the pointer P alone, but if more than twenty-five points as
say 215 then the pointer p is brought into play as follows. First raise the lever t
to throw the gears Ss out of connection and close the circuit on the wire 2 at 3 and
break it on at ", now turn the crank q which will bring the pointer p into contact
with its dial points u and thus bring the electro magnet M into operation to
make 200 points by eight pulsations of said electro-magnet; the hand P will
stand at 200 on its dial, then reverse the lever t when the gears Ss will resume
connection; now continue to turn the crank 9 until the pointer P indicates 15 on
the dial U, which will signify that fifteen pulsations of the electro-magnet I have
been made and the switch c will be on a wire contact piece corresponding to the
number 215 as shown by the sum of the hands P p, now pull out the levert which
gives the wire 4 at 2 a ground over switch arm V with wire 5 which connects with
said arm when such telegraph or telephone will be in position to "call"
subscriber No. 215 unless said No. 215 shall be engaged, in which case, if the
operators first "call" be not answered he will push in the levert and wait a minute
or so, then pull out the levert and "call" again and so on till No. 215 is found
disengaged. After communication the lever t should again be pushed in and the
crank 9 turned until his pointers indicate a normal contact with his own wire and
then pulled out again and left. The hand P should always point to zero, when
the pointer p is to be operated independently.

page_text: It should be explained that the crank is fitted on to the shaft Q with shoulder
collar at g' which will permit of said crank slightly turning backwards without
turning the shaft Q, so that crank may be moved back out of the way should it
happen to be in line when the lever t is pulled out.
Having now fully described the construction and operation of my invention,
I wish it to be understood that I do not limit myself to the precise details of
construction and arrangement shown and described, but reserve to myself the
right to vary therefrom by using the known equivalents for any or all of the
described devices, and generally to avail myself of the existing state of mechanical
and electrical science and practice in carrying out my invention within the true
spirit and scope thereof.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a telegraphic, or telephonic exchange system, a telegraphic or telephonic
exchange switch-board comprising a series of contact points arranged spirally, a
travelling switch adapted to be moved relatively to said contact points so as to
co-operate with same and the circuit connection from the said contact points to like
contact points in all like switch-boards in the said exchange system.
2. In a telegraphic, or telephonic exchange system such as is above referred to,
a switch-operating instrument comprising, two revolving hands insulated from each
other, one of said hands capable of being independently operative, the other
operative only in conjunction therewith, a plate composed of two dials insulated
from each other and in open circuit with a "central office," means such as are
above specified for operating said hands into contact with electrode points on said
dials and close said circuits; all substantially as and for the purposes specified.
3. In a telegraphic, or telephonic exchange system, such as is above referred to,
a switch-operating instrument comprising, two electrode hands insulated from each
other, one of said hands capable of being independently operative, the other
operative only in conjunction therewith, a plate composed of two dials insulated
from each other and in open circuit with a "central office," means to operate said
hands into contact with electrode points on said dials and close said circuit, and a
non-electrode hand with a dial and operative thereon only in conjunction with the
aforesaid electrode hand which is capable of independent movement, all substantially
as and for the purposes specified.
4. In combination the arrangement of subscribers' switch operating mechanism
substantially as described in reference to Figures 9, 10, and 14 in electrical con-
nection with the automatic switching mechanism of said subscribers' line at the
central office, substantially as described in reference to Figures 1 to 8 and Figure 13,
for operating the travelling switch (c) of the latter.
5. The general arrangement of parts constituting my hereinabove described
improvements in systems of telegraphic or telephonic exchanges as described and
diagrammatically represented in Figure 11, and adapted to operate as a whole
substantially in the manner and for the purposes hereinabove set forth.
Dated this 6th day of November 1894.
J. C. CHAPMAN, C.P.A.,
70, Chancery Lane, London, W.C., Filing Agent.