Improvements in Automatic Telephone Exchanges.
Year: 1898

page_text: Date or Application, 26th Oct., 1898-Accepted, 23rd Dec., 1898
COMPLETE SPECIFICATION.
Improvements in Automatic Telephone Exchanges.
A communication by THE STRONGER AUTOMATIC TELEPHONE EXCHANGE, of 947-—949,
Rookery, Chicago, in the County of Cook, and State of Illinois, United States
of America.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, G, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, 118, New Street, Birmingham, in the County of
Warwick, and 322, High Holborn, in the County of Middlesex, Civil Engineer.
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 improvements in automatic telephone exchanges, and
the principal object is to produce a system of mechanism for this purpose, which is
particularly adapted to fulfil many of the requirements which arise in practice
not heretofore attained, the same being fully described hereinafter and illustrated
in the accompanying drawings, in which:
Figure 1 is a front view and Figure 2 a side elevation of an electrical exchange
in the suspended normal position, in which is embodied the greater part of these
improvements.
Figures 3 and 3^, are detached portions of the elevation shown in Figure 2, with
several of the parts in a changed position, to illustrate the manner of operating an
automatic cut-out for a secret system.
Figures, 4, 4 and 4, show horizontal sections of a portion of several exchanges
on broken line 1, 2, Figure 1, looking downwardly, and illustrates the curved
position of the contact points, and the manner of connecting the interconnecting
wires of several exchanges, together with the relative position of the main switch-
arms, or wipers, at the normal position, and when in touch with the contact
points.
Figures and 5, illustrate the half twist of the interconnecting wires at the
point of connection with the contact pieces, and also shows that the interconnecting
wires are stripped of the insulation where they attach to the contact strip
hooks.
Figure 6 shows, respectively, a front elevation and a plan of one of the curved
metal strips which serve as end pieces for the attachment of rivets or bolts which
pass through a group of contact points comprising a number of curved insulation
pieces shown in elevation and plan view in Figure 7.
Figure 8 is a plan view of one of the curved insulating pieces, shown in Figure 7,
as it appears when attached to the exchange with the contact points in position, and
one of the wipers for contacting the same attached to its shaft and in the normal
position. Figures 8 and 8B are broken detail views of its releasing mechanism,
taken in two positions, and 8C is a detail view of the bent wire 48.
Figure 9 is a plan view of the main shaft with ratchets through which the same
is operated mounted thereon, an auxiliary switch being also shown in position;

page_text: together with three wipers, these several points being shown in the initial
position.
"
Figure 9 is an elevation same as upper portion of Figure 9; but with an
auxiliary switch-arm in the position it occupies, after six step by step rotary
movements, and after the main shaft has had the first longitudinal step by step
movement.
Figure 9B is a similar elevation, as shown in Figure 9, with the exception that,
the main shaft has had five longitudinal step by step movements upwardly, and two
step by step movements on the shaft and in the same direction as indicated also by
arrow A.
Figure 9 is a cross section of the main shaft on line 3-4, Figure 9, showing the
auxiliary switch and one of the wiper arms on the main switch, in bottom elevation,
or when looking in the direction indicated by arrow B.
Figure 9 is a horizontal section on line 5-6, Figure 9, or Figure 9B of the
rotary ratchet wheel with a plan of the auxiliary switch contact point holder and
contact arm in touch with the second contact point.
Figure 10 is an elevation and a plan of the cylindrical ratchet through which a
longitudinal movement is imparted to the main shaft, there being a projecting strip
at one side of this ratchet for a purpose which is explained hereafter.
Figure 11 shows, respectively, an elevation and a plan of the ratchet through
which a rotary movement is imparted not only to the main shaft, but to the arm of
the auxiliary switch.
Figure 12 shows, respectively, a front and side elevation and a plan of the holder
of insulating material into which are secured the several contact points or pins of
the auxiliary switch, which holder is firmly secured to the main shaft and partakes
of all its movements.
Figures 13, 13 and 13 are vertical sections of the top plate of the frame of the
exchange, and of the main shaft of broken line 7--7, Figure 2 looking in the
direction indicated by arrow C, to illustrate the action of a spring cut-out, which is
fully described hereafter.
Figures 14, 14, 15 and 15ª are diagrammatic views of two complete telephone
systems, with the exchange therefor, the same capable of being connected, the
parts being shown in the normal position, and in order to avoid complication, the
telephone, we will suppose, is of the magneto variety, and may therefore be used
for both transmitter and receiver.
Figures 16, 16, 17, 17, 18, 18, respectively, represent three interconnected
telephone systems, and the exchanges therefor, the telephone set in Figure 16,
and the one in Figure 18, being in speaking connection through the exchange in
Figure 16.
The telephone set in Figure 17 and the exchange therefore in Figure 17, and
shown connected to the exchanges in Figures 16 and 18, to illustrate the action of
an automatic secret service cut-out which each exchange is provided with, and
which effectually prevents two persons whose telephones are connected, being
disturbed in conversation by a person at any other telephone of a given system.
Similar numerals indicate like parts throughout the several views.
In the drawings, 8, indicates the several parts comprising the frame of the
exchange, to the upper part of which is pivotally mounted the shaft 9, which is
disposed vertically and is operated longitudinally upward, step by step, against
gravity, by means of a pawl 10 engaging in the teeth of cylindrical ratchet 11,
the pawl 10, being attached to the free end of an arm 10', which is operated by
virtue of electro magnet 12.
Shaft 9 is rotated, step by step, by virtue of magnet 13, through lever 14 and
pawl 14 engaging with ratchet wheel 15.
The ratchet wheel 15, in this instance, is loosely mounted upon shaft 9 and is
held in the initial position shown by helical spring 151, which has one end attached
to a downwardly projecting arm 15", and the other end to the boss 17 of the
auxiliary switch contact point holder 18, which base is firmly secured to shaft 9,

page_text: This spring holds the arm 15" normally in contact with a stop 19 projecting from
the contact point holder 18. There is a combined switch arm and coupler in the
form of the arm 20, which is firmly secured to and projects laterally from the lower
end of the ratchet wheel 15.
Near the outer end of the arm 20 is a hole 201, Figures 90, 90 and 11, which is at
a distance from the centre of shaft 9, so that, as the ratchet 15 is revolved step by
step, against the tension of spring 15, the arm 20 is carried around and at the
termination of each step the hole 20 registers with one of the contact points 21
which are secured in the insulating holder 18.
There are ten contact points 21 shown in Figures 2, 9, and 12, but a greater or
less number may be used as may be necessary.
Shaft 9 is provided with a series of wipers insulatingly secured thereto, and in
this instance all project from the same side of shaft 9.
Only three wipers 22, 221 and 2211, are shown, but more may be used in large
central stations, as may. be required.
Each wiper is connected independently by a wire to some one of the contact
points 21, and each of the several wires has an insulating covering and for
convenience the wires are formed into a cable as shown in Figures 1 and 2.
The several exchanges of any given system are each provided with one or more
groups such as 24, 24, 24" of contact point 25, Figures 1, 2 and 8, each contact
point is insulated from the other and they are not ranged in straight vertical rows,
but in concave horizontal rows as shown.
Each group of contact points is usually numbered one hundred and secured
between plates of insulating material 251 Figure, and each group is secured upon
vertical side rods 26, by means of the plates 261 Figure 6, as shown, there being
one wiper for each group.
The first contact point of each group of the top of first series of groups is
connected by an inter-connecting wire 27, with the first contact point of all the
groups of that series, and the second contact point is connected by a wire 27 with
the second contact point of all the groups of that series, and wire 27 connects the
third contact point and so on, with all the contact points of each of the other series
of groups as shown in Figures 4, 4 and 4".
At the lower end of the side rod 26, is secured an arm 28, to which is pivoted
an arm 29, whose other end is pivoted to the lower end of a short piece of round
rod 30, which projects unwardly within helical spring 31. The upper end of rod 30°
is pointed and has the bearing in the centre of lower end of the main shaft 9, which
may turn thereon, but is held in contact therewith by the tension of spring 31, which
has the lower end secured to rod 30, and the upper end to the base shown on the
lower end of shaft 9, this spring also serving to turn shaft 9 backwardly to the
normal position after it has been revolved forwardly by the action of the pawls
hereinbefore described, the pin 32 at the top end of shaft 9 serving as a
stop by contacting the insulated pin 33, which is attached to the exchange
frame S.
Spring 34 at the lower end of the exchange, serves to carry part of the weight
of shaft 9 and thus relieve the strain of pawl 10 in lifting the shaft, step by step,
vertically.
Secured to ratchet 11 is a strip of metal 35, and insulatingly attached to the
side of the top of frame 8 at 36 is a spring 36 whose top end is adapted to contact
strip 35 at any point of the upward longitudinal, step by step movement of
ratchet 11. There is a detent 37 which serves to hold ratchet 15 in any desired
operated position, and detent 37 is secured to one end of a pivotal shaft 38, and
at the other end is secured a detent 39, which engages with the ratchet cylinder 11,
so that, in the act of release both detents are simultaneously lifted from the
ratchets.
At the top of detent 39, is a laterally projecting pin 40, of insulating material,
which has a position as shown in Figures 13, 13 and 13B, so that, when the
detent 37 and 39 are out of contact with the ratchets by the rotation of the

page_text: shaft 38, the pin forces spring 36 out of the contact with strip 35 on ratchet 11,
and no current can pass from the spring into ratchet 11, shaft 9 and the frame. 8
of the exchange.
If however, ratchet wheel 15 is actuated one step forwardly, the spring 36 is
dropped into contact with strip 35 by the falling of detent 39 into engagement
with ratchet 11, as shown in Figure 13.
The means by which the conversation between two persons is made secret, is
shown in Figures 1 and 2.
At 41 and 42 are single spool electro magnets, whose spools are not directly
connected, but the two spools are secured to the same cross-piece, and at 42' is an
arm, which is not only an armature for magnets 41 and 42, but the free end thereof
projects forward to a distance sufficient to contact the two projections 43 and 44
near the end of a spring 45, whose opposite end is insulatingly attached to frame 8
at 45¹
Projection 44 ou spring 45 is a piece of insulating material, but projection 43 is
integral with the spring so that current may pass from arm 42 into spring 45
when in the normal position with arm 42 in contact with projection 43, Figure 2,
but no current can pass between these two parts when the arm 42 is drawn in by
virtue of electro-magnets 41 and 42 to the position shown in Figure 3 where the
end of arm 421 is in contact with the piece of insulation 44.
In Figure 2 is shown a bent arm 46, projecting from the base which forms the
pivotal end of arm 14. The vertically disposed free end of arm 46 is in contact
with bent wire 48, which is in the form of a bell crank, as seen in Figure 80, and
is pivoted to a block 49, Figure 1, then extending across the front plate of frame 8,
and at the free end is covered with a piece of insulating material 491.
Spring 45 extends from insulator 45' and passes over and rests upon the insu-
lated portion 491 of bent wire 48. At 51 is an insulated screw secured to frame 8,
and to this screw is attached a spring 52 and at 53 is an arm projecting from the
armature of magnet 13, the other end of which arm is normally near but not in con-
tact with spring 52, but should magnet 13 become energized, arm 53 will contact
spring 52 and bend it down, as is shown in Figure 3, and at the same time the bent
arm 46 causes the insulated end 49' of bell crank lever 48 to move spring 45 into
contact with a cross spring 55, which has one end attached to the frame of the
exchange by a piece of insulated material Figure 3, so that, if magnet 41 is
energized, the arm 421 is free to take the position shown in Figure 3, when if
magnet 41 continues to be energised until after the current is cut out from
magnets 13 and 42, the spring 45 will drop with the free end of arm 42 in contact
with the piece of insulation 44, in which position no current can pass between
spring 45 and arm 421, which arm is pivoted to and is in electrical connection with
the frame and shaft 9; therefore, anyone making an attempt to cut into either of
the lines of two already connected telephones, will automatically cut himself out
every time his main switch arm contacts either of the two contact points of the two
connected exchanges, the course of the current to accomplish this being described
hereinafter.
The manner of attaching the interconnecting wires 27 to the contact point strips,
is plainly shown in Figures 4, 4B, 5 and 54, the contact point strips 25 being
• provided with hooks at their rear ends which engage with loops successively formed
at intervals along each of the interconnecting wires, the insulating covering of these
wires being cut at the point of contact, so that the bare wire may be soldered to the
hooks to ensure a perfect connection. The insulating material being slid back on
the wire from the hook until after the soldering operation, when the insulation is
again slid forward close up to the books as shown.
In the construction of the shaft 9, and the several parts attached thereto, no
particular method is claimed of insulating the wipers 22, etcetera.
The boss 17 is firmly secured to shaft 9, and serves as a stop by contacting
frame 8, and thus limiting the downward movement of the shaft.
As has been described, the ratchet wheel 15 is loosely mounted on shaft 9 to

page_text: revolve and to slide a short distance longitudinally thereon, but when in the normal
position it is held with the auxiliary switch arm 20 above the plane of the ends of
the contact pins 21 and the lower end of the downwardly projecting arm 15" and
the lower end of boss 17 both rest upon the frame 8, as shown in Figures 1, 2 and 9.
If, however, the ratchet wheel 15 is turned one step forward, it will turn shaft 9
against the tension of spring 15 from the normal position shown in the broken
lines at F, Figure 9D, and in the solid lines Figure 90, to a position when the
hole 20 is directly over the first contact point 21, and should the ratchet wheel
be turned two steps, the switch 20 will have a position with the hole 20', directly
over the second contact point as shown, when, if from a thrust from pawl 10 against
ratchet 11, shaft 9 is lifted another step, the second contact point will be forced
into the hole at the end of the switch arm 20, and thus not only serves to establish
a circuit for an electric current from shaft 9 to the second contact pin and thence,
by wire 23 Figure 2 to wiper 221, thence to some one of the second group of contact
points in group 24 Figures 1 and 2, when the wiper is in contact therewith but also
serves as a coupler to cause shaft 9 to revolve step by step in unison with the revo-
lution of ratchet wheel 15, through the thrusts of pawl 14'. It must be under-
stood, therefore, that the auxiliary switch arm 20 must be set in this instance first
to connect with some one of the groups of contact points 24, 24', etcetera, before the
shaft 9, together with the wipers 22, 221, etcetera, are permitted to revolve, or the
shaft to move longitudinally more than one step.
Each successive thrust of pawl 10 lifts shaft 9 one step, and carries each of
the wipers 22, 221 and 22 upward, successively, even with the ten horizontal rows
of contact points 25, and it is obvious that the several wipers may be lifted to
register with any particular row of contact points, and then, by the successive thrusts
of pawl 14 at the top of arm 14. be rotated to carry the free ends of the wipers
into touch with any particular point 25 of the row.
The auxiliary switch embodied in the parts 18, 20 and contact points 21, with the
wire connecting the points with the several wipers 22, 221, 2211, etcetera serves as
a selector for connecting with some particular group of one hundred, such as 24,
24 or 241, Figures 1 and 2.
In operation, to follow the course of the successive electric currents in making
connection between two telephone sub-stations through the exchange machines at
the central station, we will suppose that one telephone set at a sub-station is repre-
sented by Figure 14 and the exchange machine directly connected thereto by two
line wires is Figure 14, and that the number of this telephone is 367.
We will also suppose that the distant sub-station to be called is No. 295 and is
represented by the telephone set in Figure 15, and its exchange machine is
Figure 15, and that not only these two telephone sets, but also the exchanges
thereof are at the normal position as shown, and that the successive currents of
electricity are controlled at the central station in each exchange machine, by means
of three ordinary signal keys at each sub-station, these keys being operated on the
decimal system and, therefore, are denominated units, tens and hundreds keys, and
are here desiguated by the letters H, T, and U.
To call 295, the H, or hundred key is pressed twice in succession, causing two
distinct electrical impulses to pass from the main battery D, at the central station,
over battery wire 56 to wire 57, Figure 14, to the single spool maguet 42, then by
wire 58 to magnet 13, then by wire 59 to wire 61 to key H, and to ground.
(It will be noted that the first time the hundred key is pressed the detents 37 and
39 are both permitted to drop upon their respective ratchets 15 and 11, which
permits spring 36 to contact metal strip 35 at the side of ratchet wheel 11, so that
current may pass between spring 36 and shaft 9).
Next press the T or tens key nine times in succession, causing nine electrical
impulses to pass from battery D through battery wire 56 to magnet 12, thence by
wire 62 to spring 36, contact strip 35 and shaft 9 to pin 32, thence to insulated
pin 33, then by wire 63 to wire 64, then wire 65 to the key T, or tens key to
ground.

page_text: (It will be noted that, when the tens key is pressed the first time the shaft 9 is
lifted longitudinally one step, which causes the auxiliary switch arm to contact one
of the pins 21 of the auxiliary switch, and thus make both au electrical and
mechanical connection, whereby the thrusts of the pawl 141 will turn shaft 9 with
ratchet wheel 15, but in this instance the shaft is lifted nine steps, when each of
the wipers 22, 221 and 22" is even with the ninth row, counting from the bottom
row of contact points 25 in each group.)
Next press the U, or units key five times in succession, causing five electrical
impulses to pass from battery Ď through wire 56, then wire 57 to one spool
magnet 42, then by wire 58 to magnet 13 and wire 59 to wire 60 and 61 to the U,
or units key and to the ground.
It will finally be noted that the first time this units key is pressed, shaft 9 is
rotated one step forwardly, which separates strip 35 from spring 36, Figure 13B,
and also Figure 16).
Every time the U or units key is pressed, arm 53 of the armature of magnet 13
contacts insulated spring 52, which causes an electric current to pass from the small
battery E, Figure 14, which controls the releasing mechanism herein before referred
to, through wire 67 to one spool magnet 41, thence by wire 68 to spring 52, thence
through arm 53 and base 8, to which it is pivoted, to shaft 9 and to arm 20 of the
auxiliary switch, which arm is in contact with the second contact pin thereof, as
shown in Figure 9D, thence by wire 23¹ to wiper 22¹ to contact point number 295 of
group 24 (Figures 1 and 2, thence by an interconnecting wire 27 to connecting
wire 69 of exchange machine, Figure 15 or 18, as the case may be, then by wire 63¹
(of this exchange number 295) to and through wire 64 to telephone lever 701, then
wire 74 to the generator 75¹ then wire 76¹, to the ringer magnets 771, then wire 591
to magnet 131, then wire 581 to magnet 42", thence through wire 571 to battery
wire 56 and wire 73 to small battery E, Figure 14, which completes this circuit and
energises the magnet 41.
The electric current, last described, in passing over this circuit must pass either
through the ringing magnets of the bell or the telephone, or in passing over the
lines of two sub-stations connected together the current is divided and passes over
both circuits.
Usually, the bell magnets are of high resistance, say one thousand Ohms, and the
telephone is of low resistance, say one hundred Ohms. The current from small
battery E in passing over this circuit as described, if it passes through the high
resistance bell ringer magnets, is not of sufficient strength to hold the armature or
arm 42 against magnet 41, after magnets 13 and 42 are de-energized, thus
permitting the arm 421 to fall back into normal position and complete the talking
circuit with any sub-station with which connection has been made.
The two telephones, 367 and 295, are now in connection and the ringing circuit
is from generator 75, Figure 14, through wire 74, ringer magnets 77, wire 59 and
magnet 13, then wire 58, magnet 42 and through wires 57, 56 and 57', Figure 15,
to magnet 42", then wire 581 to magnet 131, wire 591 to ringer magnet 771,
Figure 15, then by wire 76¹ generator 751, wire 741, telephone lever 70¹, wire 64¹,
wire 631, then connecting wire 69 to the inter-connecting wires 27 to wiper 2211 of
exchange machine Figure 14 (as shown in proper position in Figure 16) then
through wire 231, contact point number 2 of the auxiliary switch, and then the
switch arm 20 thereof, shaft 9, base 8, and arm 421, spring 45, wires 63 and 64,
telephone lever 70 of telephone set number 367, Figure 14, wire 74, and to
generator 75, which completes the ringing circuit.
The telephone number 367 and 295, are now removed from their levers 70 and 70¹,
when the talking circuit is established, the mechanism of the exchange machine in
Figure 16, being shown in the operated position connecting the two telephones.
The talking circuit is the same as the ringing circuit, with the exception of the
ringers and the generators therefore, which are cut out and the telephone switched
in.
While these two telephones are off their respective levers, should anyone attempt -

page_text: to make a connection with either of the already connected telephones, say a person
at telephone 118, Figure 17, should attempt to call a person at telephone 295,
Figure 18, and presses the H, or hundreds key twice, and the T, or tens key nine
times, and the U, or units key five times, every time he presses the units key he
closes the contact between arm 53, and spring 52, the electric pulsations from small
battery E, in passing over the circuit, which includes the low, resistance
telephone 295, is of sufficient strength to hold the arm 421 against magnet 41, and
permits the insulated contact 44 of spring 45 to fall back of and contact the frie
end of arm 421, whereby the circuit is broken, in which event, it is obvious that the
bell of neither one of the connected parties can be sounded nor their conversation
be heard.
In each of the diagrammatic views is a separate small battery E, E', or E, for
each exchange machine, in order to show as small a number of exchange intercon-
necting wires as possible, but it must be understood in practice that, one small
battery such as E, of less power than battery D, serves for several of the whole
number of exchange machines at the central station.
To cause the several operative parts to return to the normal position after a con-
versation, magnet 13 is first electrically energized and the current is not cut until
after magnet. 12 is energized, which through the pin 14" and tail piece 1011 causes
the detents and pawls to successively lift from their respective ratchets, when
shaft 9 is first revolved backwardly and then slides downwardly to the position
shown in Figures 1 and 2.
In the downward movement of the shaft the auxiliary switch is caused to resume
the released or normal position by the lower end of the downwardly projecting
arm 15 contacting the frame 8 before the shaft 9 has reached its lowest position,
which causes the boss 17 and the contact point holder 18, which are secured to the
shaft and by the downward motion thereof, to withdraw any contact point 21 which
may be engaged with hole 20' in the auxiliary switch arm 20, when the resiliency of
spring 15 causes a backward' movement of the ratchet wheel 15, to the normal
position with projection 1511 resting against projection 19 of the contact point
holder 18. Figure 9.
It will be noted that since the boss 17 and the contact point holder 18 are secured
to shaft 9, these two parts are first carried around to the normal position shown in
Figures 1 and 2, with the first backward revolution of the shaft and that, the ratchet
wheel 15 is revolved on the shaft, together with the auxiliary switch arm 20, always
after the shaft has reached its lowest position.
The shaft 9 being mounted to operate longitudinally in a vertical direction. it is
obvious that most of the weight thereof may be counterbalanced by the upward pull
of spring 34, and since a stop bearing is provided at the lower end upon the pointed
upper end of rod 30, which is disposed within spring 31. friction in the bearing
thereof is reduced to a very small amount, even when the shaft is made much longer
than is shown in the drawings to receive an additional number of switch arms, when
an additional number of groups of contact points are necessary in large exchanges.
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 correspondents, I declare that what I claim is :-
1. In an electrical exchange, the combination with a series of contact noints
arranged in groups, a switch provided with an arm for each group, a series of
contact points mounted independently of the switch but in electrical communication
with the different arms, and a selector or auxiliary switch arm rotably and
longitudinally movably mounted upon the first mentioned switch, and means for
establishing electrical communication with either of said groups through said
selector, substantially as set forth.
2. In an electrical exchange, the combination, with a series of contact points
arranged in groups, of a shaft provided with an arm for each group, a series of
contact points in electrical communication with said arms, a selector or auxiliary

page_text: switch rotatably and longitudinally mounted upon said shaft, the contact ends of
which are normally out of engagement with said second mentioned contact points,
and means for rotating the selector, and means for moving the shaft longitudinally,
whereby contact is made between the selector and one of the points, only after the
selector has been moved one or more steps from its normal position, substantially
as set forth.
3. In an electrical exchange, having a coupler or connecting instrument, motor
magnets for operating the same, means for energising said magnets from a distance,
an electro-magnet, a switch adapted to be controlled by one of the motor magnets,
means for passing an electric current through said-electro-magnets, and a switching
device adapted to be operated by the armature of said electro-magnets for
disconnecting the lines terminal from any two lines already connected, and
connecting the line terminal with any disconnected line, substantially as set
forth.
4. In an electrical exchange having a connector, a magnet for operating the
same, a circuit for energizing said magnet from a distance, a cut-out switch, a lock
for the same, an electro-magnet for controlling the lock, and a separate circuit for
the electro-magnet, substantially as set forth.
5. In an electrical exchange having a switch or connector, of an auxiliary switch
or selector, magnets for operating the same, a circuit for energizing each of the
magnets from a distance, a cut-out switch for one of the circuits, à lock for the
switch, an electro-magnet for controlling the lock, and a separate circuit for
controlling the lock, and a separate circuit for controlling the electro-magnet,
substantially as set forth.
6. In an electrical exchange having a switch or connector, of an auxiliary switch
or selector, motor electro-magnets for operating the same, a circuit for each magnet,
two other electro-magnets, each having a separate circuit, and one of such circuits
common to the circuit of one of the motor magnets, the said two other magnets
having an armature adapted to lock the switch, substantially as set forth.
7. In an electrical exchange having a switch or connector, of means for connecting
any two independent lines through said exchange, a cut-out switch, a lock for the
switch, an electro-magnet for controlling the lock, and means for passing a current
of different intensities through said electro-magnet, substantially as set forth.
8. In an electrical exchange having a switch or connector, of magnets for con-
necting any two independent lines to said exchange from a distance, a switch, an
electro-magnet, the armature of which acts as a lock for the switch, and means for
passing currents of different intensities through said electro-magnet, substantially
as set forth.
9. In an electrical exchange, the combination, with a support, of a shaft journaled
vertically therein, a movable step at the bottom of the shaft, means for moving the
shaft upwardly step by step, and means for releasing the same and permitting the
automatic return of the shaft to its normal position, substantially as set forth.
10. In an electrical exchange, the combination, with a support, of a shaft journaled
vertically therein and provided with contact arms, of a spring actuated vertically
movable step at the bottom of the shaft, means for moving the shaft upwardly, step
by step and means for releasing the same and permitting the shaft to automatically.
resume its normal position, substantially as set forth.
11. In an electrical exchange, the combination, with a support, of a shaft journaled
therein and provided with contact arms, of contact points, an arm pivotally secured
at the lower portion of the support, a rod in the arm, the upper end of which acts
as a step for the shaft, a spring connected with the arm for partially counter-acting
the weight of the shaft, and means for moving the shaft upwardly step by step, and
means for releasing the same and permitting the. shaft to resume its normal position,
substantially as set forth.
12. In an electrical exchange, the combination, with supports, of a shaft. journaled
therein provided with contact arms, contact points, an arm pivotally secured at the
lower end of the support, a rod in the arm, the upper end of which acts as a step

page_text: for the shaft, a spring secured to the arm and to the lower end of the shaft and
surrounding the rod and shaft, and means for moving the shaft upward step by step,
and means for releasing the same and permitting it to automatically resume its
normal position, substantially as set forth.
13. In an electrical exchange, the combination, with side rods, of contact points
supported by the rods, said points being insulated from each other and arranged in
straight vertical rows and concave horizontal rows, a shaft journaled concentrically to
the points, and provided with contact arms, a spring for holding the arms normally
out of engagement with the points, and means for rotating the shaft and moving
it upward step by step, and means for releasing the same and permitting the shaft
to automatically resume its normal position, substantially as set forth.
14. In an electrical exchange, the combination with side rods, of plates, thereon,
groups of contact points between the plates, said points being insulated from each
other and arranged in straight vertical rows and concaved horizontal rows, a rota-
tably spring actuated shaft journaled concentric with the points, a contact arm upon
the shaft of each group of points, and means for rotating the shaft and moving it
upwards step by step and for releasing the same and permitting the shaft to resume
its normal position, substantially as set forth.
1
1000
W. P. THOMPSON & Co.,
Agents.