US918852A - Telephony. - Google Patents

Description

R. 0.14. HASTINGS & MATHENY.

' TELEPHONY. APPLICATION FILED JUNE 15, 1907. Y 918,852; Patented Apr. 20, 1909. V 4 sums-sum 1.

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' TELEPHONY. APPLICATION r'mm JUNE 16, 1907.

RQGJM.HASTINGS&T.MATHENY- 3 WITNESSES RUBEN O. M. HASTINGS AND THURSTONMATHENY, OF, ATHENSpOHIO.

TELEPHON Y.

' Specification of Letters LlPatent.

Patented. April 20, 1909.

Application filed June 15, 1907. Serial No. 379,201.

To all whom it may concerm Be it known that we, RUBEN .O. 'M. HAS- TINGS and THURSTON MATHENY', citizens of the United States, residing at Athens, in the county of Athens and State of Ohio, have invented a new and useful Improvement in Telephony, of which the following is a specification.

This invention relates totelephony, and more especially to lock out and selective systems for use on party lines. 7

One of the principal objects of the invention is to provide a system in which the selective means are arranged in series on the limbs of an all metal talking circuit, provision being made for grounding the limbs at central, and at the opposite end of the line during theoperation of selecting and unlocking the receiver hook of a subscriber.

A further object of the invention is to provide a system in which any called or calling subscriber may cut the calling circuit beyond his station, if desired, for the purpose of preventing annoyance from the grounded calling line while talking.

A still further object of the invention is to provide a system in which the mechanism is of such nature that all of the receiver hooks will be normally locked and may remain locked until released by the central station operator, or, where provision is made for allowing each subscriber to unlock his own receiver for the purpose of calling central.

A still further obj ect'of the invention is to provide a step by step selective mechanism of such construction that after an initial movement of the receiver .hook releasing mechanism by one subscriber, and a single step movement of the selecting or unlocking means it will be impossible for any other subscriber to break in onth'e line.

A further object of the invention is to provide a receiver hook lock which may be moved to release position by the subscriber under certain conditions, and is under the control of the central station operator under all conditions. g

A still further object of the invention is to provide a selecting mechanism of such nature as not to materially increase the resistance of the line, a small relay magnet being placed in the circuit at each telephone and operating to close a normally open circuit including a local battery, and local electromagnet, through which latter movement is imparted to the selecting mechanism, so that only the resistance of a small number of small relays will be added.

. A still further object of the invention is to provide" a mechanism of this class with a line opening switch which cannot be removed to open position except at the station of the calling or called subscriber.

A still further object of the invention is to provide means whereby the two limbs of the all metal circuit may be alternately grounded, this mechanism being so arranged that after the sending of a signal to the telephone most distant from the central on one line, the

ground will be changed to the opposite line.

With these and other objects in view, as will more fully hereinafter appear, the invention consistsin certain novel features of construction and arrangement of parts, hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that var1ous changes in the form, proportions, size and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention In the accompanying drawings :Figure 1 is an elevation of a portion of a telephone switch boX showing the door in open position and illustrating a selecting and lock out mechanism constructed and arranged in accordance with the invention. Fig. 2 is an elevation, partly in section, of a portion of the mechanism showing the position of the parts atthe completion of a selecting movement, the receiver hook being unlocked. Fig. 3is a transverse sectional view on the line 33 of Fig. 2. Fig. 4 is a detail view of a portion of the mechanism showing the mannor in which the'receiver hook lock maybe manually released. Fig. 5 is a detail sectional view on the line 55 of Fig. 4. Fig- 6 is a vertical section through a-portion of the box showing the receiver hook locking pin. Fig. 7 is a detail perspective view of the manually local circuit opening device. Fig. 8 is a plan View of the mechanism arranged at the central station for connecting either limb of the circuit to the ground and the source of energy. Fig. 9 is a rear elevation of a portion of the mechanism shown in Fig; 8 and illustrating more particularly the means for advancing the indicator. Fig. 10 is an elevation of the mechanism arranged at that end of the line distant from central and employed for grounding the limbs of the circuit alternately. Fig. 11 is a detail view of a portion of the mechanism shown in Fig. 10 with the parts in a different position. Fig. 12 is a sectional plan view on the line '12-12 of Fig. 10. Fig. 13 is a diagram of a system arranged in accordance with the invention.

Similar characters of reference are employed to indicate corresponding arts throughout the several figures of the rawings.

Practically all of themeehanism at each local orsubscribefls station is arranged on the inner face of the door A of the switch box, and is mounted on two base plates 10 and 11 secured to the door.

The switch hook S is of any ordinary construction, and is arranged to be engaged by a pin 12 projecting from a lever 13 that is pivoted on a screw 14 projectin from the plate 10. This lever is normally held in locked position by a bell crank lever 15 having two arms 16 and 17, the arm 16 being arranged to engage against a lug 18 projecting from the lever at a point near the fulcrum of the latter, and when this locking lever is in place it becomes impossible to raise the switch hook S, and until the hook is raised it is, of course, impossible to connect the phone in the talking circuit, so that it becomes impossible for any of the subscribers to overhear any conversation on the line.

To the plate 10 is secured a small bridge or bracket 20, and the plate and bridge are provided with bearings for the reception of a shaft 21 to which is secured a ratchet wheel 22 that is provided with teeth of a number corresponding to the number of subscribers in the system, usually ten. The teeth of this ratchet wheel are engaged by a pawl 23 that is hung from a lever 24 carrying an armature 25 disposed within the field of force of an electro-magnet 26 that is supported by the plate 10, and each time the electro-magnet is energized, the ratchet wheel will be advanced to the extent" of a single tooth. The movement of the ratchet wheel is indicated by a pointer 27 that is mounted on a shaft 28 connected by gearing 29 to the shaft 21. The pointer travels over a suitable dial 30 arranged outside the switch box.

Secured to the shaft 21 is a disk 32 having peripheral teeth 33 of a number equal to the number of teeth ofthe ratchet wheel and facing opposite those of the ratchet wheel. These teeth 33 are arranged to be engaged by a locking pawl 34 pivoted on a stud 35 and carrying a small pin 36 that enters an opening in the armature lever 24:, the construction being such that during the downward movement of the armature lever, the pawl 34 will be undisturbed until the movement is nearly complete, and then the upper wall of the opening in the armature lever will engage the pin 36 and move the locking pawl to release position, so that as the armature lever again moves upward and the pawl 23 advances the ratchet wheel a single. step the locking pawl 34 will not interfere with the movement but will be moved inward to engage the next tooth and thus prevent excessive rotative movement of the disk or ratchet wheel through acquired momentum.

The disk 32 is provided with an annular series of openings 37 of a number equal to the number of teeth and arranged to receive a pin 38 which may be adjusted into any one of such openings, these pins being disposed at different points, respectively, in the d iil'erent telephones, and corresponding to the number by which the sub-station is known.

Mounted on a stud 40 that projects from the plate 10 is a lever 41, one arm of which is arranged to be engaged by the pin 38 as the disk revolves, and when this occurs the opposite arm of said lever operates through a spring strip 43 on the arm 17 of hell crank lever 15 and moves said bell crank lever from engagement with the receiver hook holding lever 13, so that the receiver hook may be raised from the position shown in Fig. 1 to the position shown in Fig. 2 for the purpose of connecting the telephone to the. talking circuit in the usual manner.

On the plate 10 is a block 45 formed of insulating material, and carrying a spring contact 46 which is engaged by the lever 41 when the latter is elevated by the pin 38, this being for the purpose of closing the calling circuit through the call bell, as will hereinafter appear.

The disk 32 is further provided with an annular groove 50 on the front face, the outer wall of the groove being formed by an annular rib 51 which is provided at one point with a notch 52. This notch is arranged to permit the passage of a dog or lug 54- that projects rearwardly from an arm 55 that is piv-- oted on a stud 56 carried by the plate 10. In the lower side of the arm 55 is a semi-circular notch 5'7 having a tapered wall and arranged to receive the conical end 58 of a push button 59 that projects outside the easing and is normally held outward by a spring (30, (Fig. 5). When the push button is pressed inward, the cone bears against the tapered wall of the recess and the arm 55 is raised, but this upward movement is limited by contact of the dog 54 with the annular rib 51 except when the notch 52 is immediately above the lug, in which case the arm may move upward to its fullest extent, and if moved upward the free end of the arm will engage a pin 61 that projects from the arm 16 of the bell crank lever 15 and will move the latter from looking position to the position shown in Fig. 4.

Under normal conditions the position of the notch 52 is as shown in Fig.1 if all of the the notch 52 will normally be immediately above the lug, so that at any phone the button may be pressed in forthe purpose of releasing the receiver hook and allowing the subscriber to call central over the talking circuit.

Pivoted on the arm 55 is a locking pawl 61',

arranged to engage a lug 62 that projects from the lower side of the bridge 20. The tail of the pawl is arranged to be engaged by a pin 62 that projects from the rear or lower face of the ratchet wheel 22, this pin being adjustable to diiierent positions in the different phones. When the pin moves into engagement with the tail of the pawl it releases the latter from engagement with the lug 62, so that the arm is free to move'upward for the purpose of releasing the receiver hook locking mechanism.

It will be understood that where the notch 52 is normally out of alinement with the lug 54, this pawl will not be necessary, but where the mechanism is so arranged that the notch is normally in alinement with the lug, the pawl becomes essential in some cases, for the reason that it will allow the mechanism to be placed strictly under the control of the central operator, and the button cannot be depressed for the purpose of raising the arm until the disk has advanced to such an extent that the pawl is released from the lug 62.

Secured to the plate 11 is a small electromagnet 63 below which is arranged an armature 64 carried by a lever 65 that normally rests against a stop pin 66. Mounted on an insulated block on the plate is a contact 67 which is engaged by the armature lever 65 when the armature is raised for the purpose of closing the circuit through the electromagnets 26.

Extending through the door A is a small shaft 70 at the inner end of which is secured a metallic arm 71 that may be moved into and from engagement with a contact 72 for the purpose of controlling the circuit through the electro-magnet 63. The arm 71 carries a block 73 of insulating material which normally bears against the lower edge of the le ver 13 and is held l'rom'upward movement,

and, therefore, in contact with theterminal 72 so long as the locking lever 15 is in operative position. To the outer end of the shaft 70 is secured a handled operating lever 76 that is arranged within convenient reach of the subscriber, this lever being moved in ore der to break thecircuit between contacts 71 and 72, and thus prevent any subscriber on the line from' sending in a call.

' binding post 8 1, and wire 81.

' Referring now to Fig. 13 it will be seen that the talking circuit of each telephone is bridged between the lines 80 and 81. The talking circuit is arranged as usual and requires no further description, while the selecting circuit is connected to either the wire 80 or the wire 81, as'the case may be, the wire being cut and attached to binding posts 83-84. From the binding post 83 extends a wire 85 to lever 71, contact 72 and from thence thecircuit may be traced through wire 86, relay magnet 63, and wire 87 bacl; to the Ir, now, the

opposite ends or the wire 81. be grounded and a current sent over the line, all of the electroinagnets 63 in the stations oi wire 81 will be energized, and being energized, will attract the armature e4, raising lever 65 into engagc- Iment with contacts 67, whereupon the circuits of the electro-magnets 26 will be closed. Each electro-magnet 26 is arranged in a local circuit, which includes batteries 89, part of which may be employed on the primary or" the talking circuit. Fl'Ol'll the bat- 26, and thence the circuit flows from electro magnet to Wire 91, contact 67, armature lever 65, and wire 92 back to battery, so that each time the electro-magnet 63 is energized the electro-1nagnet 26 will be energized "from its localbattery, and the selecting mechanism 1 will be advanced a single step. By opening and closing the circuit the proper number of times, the selecting pin 38 of any desired station may be brought under the lever 11 for the purpose of raising the latter into engagement with'the contact s ring 16, and when this occurs a circuit wil be closed through the call bell C, from wire 80, wire 97, to plate 10, the selecting mechanism, pin 38, or lever 41, contact spring 46, wire 98, call bell 0, wire 99, back to line wire 81, thus bridging the bell C in the main line, so that the call may be sent in the usual manner.

Arranged at the central station is a circuit closing device for controlling the selecting in echanism.

Mounted. on a base plate is a switch blade 101 that is nornially held in idle central position, as shown in Fig. 8, and this a circuit between two switch blades 102 and 103, or to the opposite side to close a circuit between two blades or tern 'nals 104-, 105. The blade 102 is connected. to binding post 106 to which leads the wire 81, while the blade 103 is connected to a post 107 from which leads a wire 108 to a source of energy, such, for instance, as a storage battery 100. From the storage battery leads a wire 110 to an electro-niagnet 113. From the electro-nz.agnet leads a ground wire 1.16. On the opposite side the switch blade 104 is connected to a binding post 117 to which the wire 80 is connected. Theblade is tery leads a wire 90 to the electro-niagnets c switch may be moved to one side to close connected to a binding post 118 from which leads a wire 119 to the battery 109. It will be seen, therel'ore, that if the switch 101 is moved to engage the blade 102103, a circuit will be closed from ground through the storage battery 109 and along the line 81, and all of the eleetro-magnets 63 con.- nected in that line to the extreme end of the line, provision being made for grounding this end of the line. 11'' the switch is moved in the opposite direction to engage the blades 104*105, a circuit will be closed from ground through the battery 109 and wire to the opposite end of wire 80, provision being made or grounding this end of the line 80.

The electro-1nagnet 113 at the central station is for the purpose of operating mechanism which will indicate the number of times the circuit is closed. This mechaniszn is shown m ore fully in Fig. 9.

Arranged below the electro-magnet 113 is an armature 127 carried by a lever 128 to which is hung a pawl 129 that engages a ratchet wheel 130, carried by an arbor 131, the latter being mounted in bearings formed by a bridge 132 and an inclined plate 133 that is supported by the base 100 and is arranged directly in front of the operator. The arbor 131 extends through the plate 133 and carries a pointer 134 that is arranged to travel around a graduated dial, (Fig. 8), the graduations of the dial corresponding to the teeth of the ratchet wheel, and each time the electro-magnet is energized by the closing 01 the circuit through the wire 80, or the wire 81, the pointer will be advanced a single step. The ratchet wheel is held from backward movement by a spring actuated pawl 137, and ,xcessive movement is pre vented by a pawl 138 that is pivoted on a pin 139 and which carries a pin 140 fitting within a cam opening in the lever 128, the function of the pawl 138 being to engage a toothed wheel 141 that is secured to the arbor 131 and prevents movement of the ratchet wheel to a greater extent than one tooth at each operation.

Inasmuch as the two limbs of the talking circuit are independently used for signaling, it becomes necessary to employ means for insuring the grounding of these limbs. This mechanism is shown in Figs. 10, 11 and 12. Mounted on a suitable base 150 is a pair of electro- magnets 151, 152, one of which is connected to the line wire 80 and the other to the line wire 81. Arranged below the electro-magnet 151 is an armature 153 carried by a lever 15 1 on which is hung a pawl 155 arranged to engage the teeth of a ratchet wheel 156 that is secured to an arbor 157, mounted in bearings formed in the plate 150 and a bracket 158. The bracket, also, carries a spring actuated locking pawl 159 which engages and prevents backward m ovement of the ratchet wheel 156.

Arranged below the electro-magnet 152 is an armature 160 carried by a lever 161 from which is hung a pawl 162 that engages the ratchet wheel 163 also secured to the arbor 157, so that when either electro-magnet is energized, by the sending of a current over either line 80 or 81 the arbor 157 will be turned.

Secured to the rear portion of the arbor 157 is a disk 170, the periphery of which is provided with locking teeth that are arranged to be engaged by locking pawls 171 pivoted on the base plate and actuated by the armature levers, these pawls entering between the locking teeth for the purpose of preventing excessive movement of the disk and ratchet wheels through acquired momentum. The disk 170 further carries a segment 173 formed of insulating material and serving as a cam for engaging a pair of levers 174 175, which are pivoted on small brackets extending from the base plate and are normally pressed in the direction of the disk by suitable springs 176 excessive movement being prevented by step pins 177. The levers 17 1175 are connected to the electroniagnets 151-152 by wires 1801S1, respectively, and said levers when actuated by the insulating cam 173 are moved outward into contact with spring circuit closing strips 182-183, respectively, these strips being connected to the line wires S0S1, rcspectively. The circuit from either line wire through the connections and electro- niagnets 151 or 152 is grounded by wires 184.

The cam strip 173 extends for slightly more than half the circumference of the disk 170, and its advanced end is inclined, as shown in Fig. 11, so that it may more readily engage with and move the levers 174;175 outward. Under all conditions one or more of the levers will be moved outward for the purpose of grounding one or other of the lines, and if line 80 be normally grounded and contain five sub-stations, the central operator may call any one of these live subscribers by moving the switch 101 at the cen tral station the proper number of times, and each time the line is closed with the battery at ground, all of the electro-magnets 63 on the line, as well as the electro-magnet 151 will be energized. The contact lever 17 1 will be held closed during the five closings and openings of the line for calling up sub-station No. 5, and then on the next movement the insulating cam will pass from the contact 174 into engagement with the contact 1.75, and will shift the ground from the line 80 to the line 81, so that the operator may then call any one of the stations along the line 81.

Briefly described, the operation of the systern is as follows :When any subscriber 9i 8,852 El) wishes to make a connection he turns his magneto-generator M, which, being bridged across the line, will send a signal to the central station, the receiving mechanism and the operators set at central being omitted from the drawing for the sake of clearness. As the magneto generator M sends out an alternating current along the line, the electro-magnets 63 at the dilierent local stations will be energized and there will be a tendency to vibratory movement of the armature 65 of said electro-magnets. in order, however, to prevent said armatures moving to positions to close the local circuits through the selecting devices, the armatures may beprovided.

with retarding devices of any well known type, so that the armature will be sluggish and will not respond to the rapid alternating current, but will only move to circuit closing position after the circuit has been energized for an appreciable length of time by a direct current from the storage battery 109. As these retarding devices are old and well known in selective telephony, they have not been illustrated in the drawing. T he central' operator then closes the ground of line 80 or line 81, or both, if necessary, so as to send a single impulse along the line, and at each of the subscribers stations the electro-magnet 63 will be energized. This attracts the armature 65 and closes a circuit from the local battery of each station through wire 90, electro-magnet 26, wire 91, contact 67, armature lever 65, wire 92, back to battery. On the energizing of the electro-magnet 26 the armature 25 is attracted, and armature lever 24 is raised, thus pulling up the pawl 23 and moving the ratchet wheel 22 to the extent of a single tooth. This brings each notch 52 of the disk 32 in alinement with lug 54 and at the same time the pin 62 of the ratchet wheel engages the tail of the pawl 61 and moves the latter from the lug or shoulder 62, so that the lever 55 willbe released. The calling subscriber then pushesin on the button 59, and the cone-shaped end of this button engages and raises the lever 55, so that the lug 54 passes through the notch 52 of the annular rib 51 and the free end of the lever engages against the pin 61 and shifts the bell crank lever 15 from the locking lever 13. The receiver hook is now unlocked, and when the receiver is removed from the hook the lever 13 moves upward to the full line posi-,

tion shown in Fig. 2. The subscriber having now connected his talking circuit to the line,

informs the operator of the numberof the station to which he wishes to be connected, and the central station operator closes and opens the line along 80 or 81 the desired number of times to reach the desired subscriber. On the first movement of all of the disks 32 after the receiver of the calling subscriber has been removed from the hoolg the notches 52 of all of the disks will be moved past the lugs 54 of the levers 55 and the lug 54 of the calling subscriber will be locked in the groove 50, while the lugs 54 of all of the remaining subscribe-rs will be locked outside the annular scriber to be called engages the lever 41 and moves the same to the position shown in Fig. 2. During the movement'of the lever 41 the spring arm 43 carried thereby will engage the arm 17 of the bell crank lever 15 and move the samefrom engagement with the shoulder of the locking lever 13, thus releasing the receiver hook switch at the station of the called subscriber. At the same time the lever 41 will move into engagement with the switch 46, thereby connecting the bell C of the calledsubscriber in the lines 80 81, so that by sending asignal over these lines the call bell of the subscriber may be rung, and when this called subscriber removes his receiver, the hooks will rise in the usual manner and bridge the local talking circuit in the line. It then becomes the duty of the called subscriber to move the switch 71, which, being disconnected from the contact 72 breaks the line 81 beyond him, so that no subscriber on that line can interfere.

When the disks 32 are so arranged that the notches 52 are normally opposite the lugs 54,

any subscriber is free to release his receiver hook when the line is idle andcall central, but the first energizing of the line by central will immediately lockout all of the remaining subscribers on the line.

While the electro magnets 151 and 152 have been described as connected directly in the calling circuits, it is obvious that they may, of course, be connected to separate local batteries and relay magnets employed in the calling circuits for controlling the local circuits in the same manner as in the subscribers stations.

We claim 1. In telephony, a party line system including an all metal circuit to which the local talking circuits are bridged, selecting means arranged at the local stations and connected in series in the limbs of the circuit, means for grounding the opposite ends of the limbs of the circuit, a receiver hook switch at each station and means for locking the receiver hook switches at all stations except those of connected subscribers.

2. In telephony, an all metal talking circuit, between which the local talking circuits are bridged, selecting mechanisms arranged at each station, an electro-Inagnet for each selecting mechanism, the electro-magnets being connected in series with the limbs of the circuit, means for grounding the opposite ends of such limbs, a receiver hook switch at each station and means for locking the receiver hook switches at all stations except those of connected subscribers.

3. In telephony, an all metal circuit between which the talking circuits of the local stations are bridged, a selecting device including an electro-magnet at each of the local stations, said local electro-magnets being connected in series to the limbs of the circuit, means at the central station for connecting a central station end of either limb of the circuit to a source of energy and ground, and means for grounding the opposite ends of the limbs of the circuit.

4. In telephony,an all metal circuit between which the local talking circuits are bridged, a selecting device including an electro-magn'et at each local station, the local electro-magnets being connected in series with the limbs of the circuit, means at the central station for connecting either limb of the circuit to a source of energy and ground, and means at the opposite end of the line and under the control of the central station operator for grounding either limb of the circuit.

5. In telephony, an all metal circuit between which the talking circuits of the local stations are bridged, a local call bell bridged in the circuit, the call bell circuit being normally broken at each sub-station, a selecting means including an electro-magnet at each sub-station, said electro-magnets being connected in series with the limbs of the circuit, means at the central station for energizing the selecting circuit, mechanism operable by the selecting means for closing the call bell circuit, and means at the distant end of the line and under the control of the central station operator for grounding either limb of the all metal circuit.

6. In telephony, a central station, and a plurality of local stations connected by an all metal circuit to which the talking circuits of the local stations are bridged, selecting means including an elect-ro-magnet at each of the local stations, the local stations being divided into two sets, each connected to one limb of the all metal circuit, the electro-magnets being connected in series, and means under the control of the central station operator for grounding the ends of the limbs and separately energizing such limbs and the electro-magnets connected therewith.

7. In telephony, a central station, and a plurality of sub-stations, an all metal circuit to which the local talking circuits of the local stations are bridged, a selecting means including an electro-magnet at each local station, said electro-magnets being connected in series to the limbs of the circuit, means at the central station for separately connecting the central station ends of such limbs to a source of energy and ground, and means at the opposite end of the line and under the control of the central station operator for alternately grounding the distant ends cl such limbs.

8. In telephony, a selecting means at each local station, comprising a normally open charged local circuit, an electro magnet in said circuit, a selecting device under the control of said electro magnet, another electro magnet in series with one ol the main line conductors, and circuit closing means for the said local circuit under the control of the last named electro magnet.

9. In telephony, a selecting means at each local station, comprising a normally open charged local circuit, an electro magnet in said circuit, a selecting device under the control of said electro magnet, another eleci'ro magnet in series with one of the main line conductors, an armature for the last named electro magnet, and means under the control of said armature for closing the normally open circuit including the :tirst named elect ro magnet.

10. In telephony, an all-metal main line, a call bell arranged at each local station and 'bridged to the main line, the local call bcll circuits being normally open, a selecting device arranged to close said circuit alter a predetermined number of operations, an electro magnet for actuating the selecting device, a

normally open charged local circuit including said electro magnet, and another electro magnet connected in series with one of the main line conductors and controlling the'normally open circuit of the 'l'irst named eleciro magnet.

ll. In telephony, a central station, and local stations each including a receiver hook, and a pair of receiver hook locks at each local station, one of such locks being solely under the control of the central station operator, and the other lock being releasable by the subscriber ol' the local station.

12. In telephony, a central station and local stations, each including a receiver book, a receiver hook locking member, means under the sole control of the central station operator for moving said locking member to release position, and a manually o )erable means at each local station [or independently moving said locking member to release position.

13. In telephony, a central station and local stations, each including a receiver hook, a receiver hook locking lover, a releasing device arranged at each local station and under the sole control of the central station operator, a manually operable means at each local station for moving the locking member to release position, and means operable from the central station for controlling the movement of said manually operable releasing mechanism.

14. In telephony, a central station and local stations, each including a receiver hook, a locking device therefor, a manually operable releasing lever, a lug projecting therefrom, a notched disk with which the'lug engages, said disk controlling the releas,

ing movement, and a step by step selecting means for revolving said disk.

15. In apparatus of the class described, a receiver hook, a receiver hook locking memher, a manually operable releasing lever having a projecting lug, a step by step selecting mechanism, and a grooved disk carried thereby, said disk having a notch atone point to permit the entrance of the lug.

16. In apparatus of the class described, a receiver hook, a receiver hook look,'a manually operable releasing lever having a projecting lug, a step by step selecting mechanism, a grooved disk operable by such mechanism and having a notch for the reception of the lug, a locking pawl carried by the lever, and means operable by the selecting mechanism for moving said pawl to releaseposition.

17. In apparatus of the class described, a receiver hook, a receiver hook look, a lock releasing lever having a projecting lug, a step by step selecting mechanism, a disk operated thereby, said disk being grooved and provided with a notch for the reception of the lug, a pawl carried by the lever and arranged to engage a stationary part of the apparatus, to hold the lever from movement, and a pin carried by the selecting mechanism and arranged to move said pawl to release position.

18. In apparatus of the class described, a central station and local stations each including a selecting means, said selecting means being connected in series to the limbs of the circuit, a source of energy arranged at the central station, and a switch under the control of the central station operator for connecting the source of energy between the ground and either limb of the circuit.

19. In apparatus of the class described, a central station, andlocal stations, the talking circuits of the latter being bridged in the main line, selecting mechanisms arranged at the local stations and connected in series to the limbs of the circuit, and a step by step mechanism at that end of the line distant from the central station and operable from the central station for shifting the ground alternately from limb to limb.

20. In apparatus of the class described, a central station and local stations, the talking circuits of the latter being bridged in the main line, selecting mechanism arranged at the local stations and connected in series to the limbs of the circuit, a pair of switches arranged at one end of the line distant from the central station, said switches being arranged to connect the limbs of the circuit to ground, a ratchet wheel arranged between the switches, an insulating cam carried thereby and arranged to engage and alternately close such switches, and means for imparting a step by step movement to the ratchet wheel.

21. In telephony, a central station and local stations, the talking circuits of the latter being, bridged in the main line, selecting mechanism arranged at the local stations and connected in series to the limbs of the circuit, switches arranged at that end of the line distant from central and adapted to alternately close to connect the limbs of the circuit to ground, a shaft, an insulating cam carried thereby and arranged to alternately engage and close the circuits, a pair of ratchet wheels carried by said cam, a pair of electro-niagnets connected in series with the limbs, and pawls under the control of such electro-magnets engaging said ratchet wheels.

In testimony that we claim the foregoing as our own, we have hereto affixed our signatures in the presence of two witnesses.

RUBEN C. at-HASTINGS.

THURSTON MATHENY. Witnesses:

WILL. J. HAs'rrNes,

. RUFUs CARPENTER.

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