US1731217A - Party-line automatic telephone system - Google Patents

Description

Oct 8, 1929. R. G. RKZHARDSON ErAL PARTY LINE AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. 25, 1925 2 Sheets-Sheet Oct. 8, 1929. R. G. RICHARDSON ET AL 1,731,217

PARTY LINE AUTOMATIC TELEPHONE SYSTEM Original Filed Feb. 23, 1923 2 Sheets-Sheet 2 rm Rodney EE1chards0nand-Juhn I. B elZam Patented Dot. 8, 19.29

UNITED STATES PATENT OFFICE RODNEY G. RICHARDSON, F CHICAGO, AND JOHN I. BELLAMY, 0F BROOKFIELD, ILIaI- NOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, T0 AUTOMATIC ELEC'IRIG ING, OF CHICAGO, ILLINOIS, A C ORPORATI'EON 0F DELA'WARE PARTY-LINE AUTOMATIC TELEPHONE SYSTEIVL The present invention relates to selective ringing party line telephonesystems in gen mentused in a system of this nature to select the ringing current is reduced to a minimum.

Other objects will be met with and explained from time to time during the course of the specification.

In order to carry out the main obj cct of the invention, the ringing of called stations is divided into as many periods as there are stations on a line, and ringing current of the proper sort to signal one station only, is placed on the common ringing circuit during each period. Then, to call-the desired station on a party line, it is necessary only to connect the common ringing circuit to the line during the proper period. This is accomplished by a ringing relay in the connector circuit which is connected to one of a plu rality of pick-up conductors, depending upon the station being called. This ringing relay, upon energizing over one of the pick-up conductors, which it does when the source of ringing current corresponding to the pick-up conductor in use is connected to the common ringing circuit, connects the common ringing circuit to the called line and maintains the connection until the end of that ringing period is reached. The ringing relay operates the same way each time that ringing period recurs.

The accompanying drawings, comprising Figs. 1 and 2, show by means of the usual circuit diagrams a sutlicient amount of apparatus in a system embodying the principles of the invention to enable the invention to be ex plained and understood. In order for Figs.

' Original application filed February 23, 1323, Serial No. 620,603. Divided and this application filed January Serial No. 84,261.

1 and 2 to be understood best, they should be arranged in order with the corresponding lines at the ends thereof in alignment.

Figure 1 shows the substation A of which the line terminates at the exchange in the line switch C, and the selector E which is accessible to the line switch G. This drawing shows also the second selector E (denoted by the dotted rectangle bearing that reference character) accessible to the first selector E.

Figure 2 shows the connector H which is accessible to the selector E, Fig. 1. The connector H has access to a number of lines, of which the party line on which the substations A A inclusive, are located is one. drawing shows also the common interrupter I and the associated ringing interrupter relays. Since the system disclosed is a terminal per station party line system, the intermediate distributing frame I. D. F. is provided in ad dition to the main distributing frame M. D. F. Referring now particularly to Fig. 2, the invention will be described generally with reference thereto. The line of substation A terminates as usual at the line side of the main distributing frame M. D. F., and is connected by the two-wire jumper 168 to the protector side of the M. D. F. The protector side of the M. D. F. is connected by switchboard cables to the line switch side of the intermediate distributing frame IQD. F. The three conductors for the line switch are taken off the line switch side of the I. D. F., as shown. Since the line of substation A is a party line, the associated contacts on the line switch side of the I. D. F. are not jumpered directly to the connector bank side of the I. D. F., but are connected by means of the jumper 162 to a so-called idler block. one of these being used for each four-party line.

The idler block shown has five sets of terminals. One or" these sets of terminals is used up by the jumper 162, leaving the other four for jumpers such as 161, between the idler block and the connector bank side of the The idler block shown, it may be stated, is representative of the others.

.The contacts of the connector banks are cabled over to the connector bank side of the I. D. F. and are there connected up in order.

This

Each set of connector bank contacts represents a station which may he a station on an individual line or a station on a party line, depending upon to where the associated jumper, such as the jumper 161 is connected.

When a party line station is signalled, it is necessary that the signalling be done in such a manner that the other stations on the line are not signalled. In this particular case, the ringers of the stations on a four-party line are connected from either side of the line to ground, thus allowing a semi-selection to be made by merely ringing on one side of the line or the other. In order to complete the selection, or, in other words signal the correct subscriber, one ring and two rings, respectively, are assigned to the stations whose ringers are connected between the same side of the line and ground. This is designated in the drawings by the references 2, 2+, etc, the numerals referring to the number of bells to which the subscriber is instructed to respond and the minus and plus signs referring to the side of the line to which the ringers are connected.

In order to choose the number of rings and. the side of the line to which the ringing current is to be appli d when any particular station is called, a pick-up or ringing relay, such as relay 201 of the connector H, is provided for each connector. This relay is controlled in accordance with the cross connection of the bank contacts engaged by the ringing current wiper 151 of the connector H, and when energized, connects the common ringing leads 215 and 216 to the called line at the same time that the ringing current is placed on the proper common ringing lead by one of the ringing interrupter relays 211-2141, inclusive.

The contacts in the bank of wiper 151 of wuich one is provided for each station called by way of t is connector H, are cabled to the left-hand side of the'l. D. F. along with the line and test contacts as shown. Since there are tour connector bank contacts in each set, the jumpers, such 1-61, are four-conductor jumpers and the fourth conductor of each connects with one of the tour pick-up conductors 251254: inclusive, which connected to the idler blocks, as shown. The correct pick-- up conductor is, therefore, connected back to the ringing current terminal of each station, and provides for controlling the ringing relays, such relay 201 of the connector H, in such a manner that the common ringing leads 215 and 216 are connected to a called line during the time when the desired code is being applied to the iiroper one of these conductors, the time at which the leads 21.5 and 216 are connected up to a called line depending, in any one case, upon to which of the four sets oi? terminals on the idler block the terminals of the selected station are connected.

It will be noted that the one ring pick-up conductor 251 is connected. to the bottom terminal of the set 120 on the I. D. F. Thebottom terminals of all such terminal sets are connected to either conductor 251 or conductor 253. This bottom terminal and the connection thereto is not used when the associated line is a party-line, but it is used, as in Fig. 1 for substation A, to take care of signalling a subscriber on an individual line by one ring as is generally done.

The substations, such as A to A inclusive. are of the usual automatic type and have, in addition to the other well-known instrumentalities, calling devices for controlling the automatic switches.

The individual line switches, of which the line switch C is typical, are mechanically of the rotary type of which the wipers have no normal position and move in a forward dire tion only. The selector and connector switches such as the selectors E and E and the connector H are mechanically of the wellknown vertical and rotary type of switch and, accordingly, their bank contacts are arranged in horizontal rows or levels.

The interrupter I may have any desired mechanical construction and, as shown, has an arm or Wiper which is adapted to operate continuously over its field of contacts.

In order to explain the operation of the system, it will be assumed that the subscriber at substation A desires to converse with the party line subscriber at substation A. In order to do this, the subscriber at substation A removes his receiver and then dials the directory number of the desired subscriber.

l fhen the receiver is removed at substation A, line relay 14 energizes over line conductors 11 and 12. Upon energizing, line relay 14 places ground on private normal conductor 30 at armature 20, thereby making the calling line busy, and closing a circuit for switching relay 13 and stepping magnet 15 in series. As a further result of the energization of line relay 14, it connects test wiper 22 to the junction of switching relay 13 and stepping magnet 15 at armature 19.

In case the trunk upon which the wipers.

of the line switch are standing is idle, switching relay 13 energizes immediately. Assuming the trunk to be busy, however, switching relay 13 is short-circuited by ground encountered on the busy test contact by test wiper 22 and does not energize, and the wipers are rotated step by step by the buzzer-like action of stepping magnet 15, which operates holding circuit at armature 17, and at armatures 16 and 18 disconnects line conductors l1 and 12 from the winding of line relay 14 and ground, and extends them by way of wipers 21 and 23, bank contacts 24 and 26, conductors 27 and 29, and armatures 58 and 61 and their resting contacts to the upper and lower windings of line relay 41 of the selector E.

Line relay 41 now energizes over the calling subscribers loop and closes at armature 52 a circuit for release relay 42. Upon energizing, release-relay 42 opens a point in the circuit of release magnet 46 and prepares a circuit for vertical magnet 47 at armature 54, and at armature 53 places ground on release trunk conductor 28, thereby closing the usual holding circuit for switching relay 13 of the line switch C before the slow-acting line relay 14 has had time to deenergize.

When the calling subscriber operates his calling device in accordance with the first digit in the desired number, the circuit of line relay 41 is opened a corresponding number of times. Each time line relay 41 deenergizes in response to one of the interruptions thereby produced, it closes a circuit for vertical magnet 47 as follows: from ground by way of the resting contact of armature 60 and said armature, armature 52 and its resting contact, armature 54 and its working contact, relay 4'3, and vertical magnet 47 to battery. By the operation of vertical magnet 47, the wipers 62-64, inclusive, are raised opposite the desired lever of bank contacts. Belay 43 is energized in series with vertical magnet 47 and, being slow-acting, retains its armature attracted throughout the vertical move ment. As a result of the energization of relay 43, it closes a circuit at armature 55 for stepping relay 44 by way of 01? normal contacts 51, which close upon the first vertical step, and interrupter contacts 50. Stepping relay 44, upon energizing, closes a locking circuit for itself at armature 56, and at armature 57 prepares a circuit for rotary magnet 48.

At the end of the vertical movement, slow acting relay 43 deenergizes and completes the circuit of rotary magnet 48 at armature 55. Rotary magnet 48, upon energizing, advances the wipers 6264, inclusive, into engagement with the first set of bank contacts in the selected level, and, near the end of its stroke, opens the circuit of stepping relay 44 at interrupter contacts 50. Stepping relay 44, upon deenergizing, opens the circuit of rotary magnet 48 at armature 57 whereupon rotary magnet 48 deenergizes also and closes its interrupter contacts 50 again. case the trunk terminating in the first set of bank contacts is idle, switching relay 45 energizes immediately. Assuming the trunk to be busy, however, switching relay 45 is shortcircuited by the ground potential encountered by test wiper 63, and stepping relay 44 energizes from this same ground potential and Inv closes the circuit of rotary magnet 48 again, whereupon the switch wipers are rotated inw engagement with the next set of bank cont acts. This alternate operation of stepping relay 44 and rotary magnet 48 continues un- 42; and at armatures 58 and 61 disconnects conductors 27 and 29 from the windings of line relay 41, and extends them by way of wipers 62 and 64, bank contacts 65 and 67, and the associated line conductors to the windings of the line relay of the selector E.

The line and release relays (not shown) of the selector E now energize and prepares the switch for operation.

When the calling subscriber operates his calling device in accordance with the second digit in the desired number, the selector E raises its wipers opposite the desired level of bank contacts and then selects an idle trunk. It will be assumed that the trunk selected at this time is the one extending to the connector H. That being the case, line relay 101 of the connector H energizes over the calling line and closes a circuit for release relay 103 at armature 128. Release relay 103, upon energizing, makes the usual circuit preparations at armatures 130 and 131, and at armature 129 places ground on release trunk conductor 75, thereby closing the usual holding circuit for the preceding switches C, E, and E.

When the calling subscriber operates his calling device in accordance with the third digit in the desired number, a corresponding number of interruptions are produced in the circuit of line relay 101. In response to each of the resulting deenergizations of line relay 101, an impulse of current is sent to vertical magnet 111, the first impulse of current being sent over the following circuit: from ground by way of armature 128 and its rest ing contact, armature 131 and its working contact, contact of off normal spring, series relay 104, and vertical magnet 111 to battery. By the operation of vertical magnet 111, the switch wipers 149l52, inclusive, are raised step by step until they stand opposite the desired level of bank contacts. Belay 104 is en-- ergized in series with vertical magnet 111 on the first impulse of current and, being slow-acting, retains its armature attracted throughout the vertical movement; By attracting its armature 132, relay 104 serves to maintain its own circuit and that of vertical. magnet 111 intact after the off normal springs have shifted, as they do upon the first vertical step. At the end of the vertical movement, relay 104 deenergizes and transfers the operating circuit from the vertical'to the retary magnet. 7

When the callin subscriber operates his calling device in accordance with the next and last digit of the desired number, the line relay 101 is deenergized a corresponding number of times. Upon each deenergization of line relay 101, an impulse of current is sent to rotary magnet 112, the first impulse of current being sent over the following circuit: from ground by way of armature 128 and its resting contact, armature 131 and its working contact, normally open contacts controlled by off normal spring 114, armature 132 and its resting contact, resting contact of armature 139 and said armature, armature 146 and its resting contact, and rotary magnet 112 to battery. By the operation of rotary magnet 112, the wipers 149- 152, inclusive, are rotated step by step into engagement with the contacts 153-156, inclusive, of the called line. Relay 108 is energized in multiple with rotary magnet 112 upon tl e first impulse of current being delivered to the latter and, being slow-acting, retains its armature attracted throughout the rotary movement. Upon energizing, relay 108 disconnects test wiper 150 from the upper winding of switching relay 109 and connects it to busy relay 105 at armature 141, and at armature 142 places a shunt around armatures 1.39 of busy relay 107 and its resting contact so as to guard its own circuit and that of rotary magnet 112 from being opened prematurely by busy relay 107, in case that relay energizes during the rotary movement, due to test wiper 150 passing over busy test contacts.

Assuming the called line to be busy, busy relay 107 is energized through test wiper 150 from ground on contact 154 when the switch wipers stop on the chosen contacts, and slow acting relay 108, upon deenergizing after the last impulse of current is delivered, disconnects itself and rotary magnet 112 from the operating circuit at armature 142, and at the normally closed contacts controlled by armature 141 completes a locking circuit for busy relay 107, which includes the working contact of armature 130 and said armature and armature 138 and its working contact. Since, busy relay 107 is maintained energized, the lead from the busy signalling machine is con nected up to the lower heavy talking conductor at armature 140 and, accordingly, busy tone is sent back to the calling subscriber to inform him that he cannot obtain the desired connection for the time being. Upon hearing this busy tone, the calling subscriber is expected to replace his receiver, whereupon the connection is released in a manner similar to that to be described hereinafter.

Assuming now that the called line is idle when called as hereinbefore described, there no ground potential on test contact 154 and busy relay 10? is, therefore, not energized when the switch wipers come to rest upon the contact associated with the called station. Under these conditions, slow-acting relay 108, upon deenergizing, completes a circuit for the upper winding of si itching relay 109 in series with the combined switching and cutoil relay of the called line switch (not shown) The part of this circuit that is shown is as follows: from ground by way of the working contact of armature 130 and said armature, armature 138 and its restingcontact, upper winding of switching relay 109,1esting contact of armature 1'41 and said armature, test wiper 150, test contact 154, a conductor of jumper 161, a conductor of jumper 162, and thence by way of the private normal conductor 164 to battery by way of the cut-off relay of the line switch associated with the called line. The line switch associated with the called l ne as has been explained hereinbefore, is similar to the line switch C. Accordingly, the cut-off relay corresponds to cut-off relay 13 of the line switch C and is energized in series with the associated stepping magnet, similar to the stepping magnet 15 of the line switch C. Due to the usual me chanical interlocking device between the armature of the cut-off relay of the called line switch and the armature of the associated line relay, the cut-oil relay is energized only half way, and as a result, the wipers of the called line switch are not connected up. I

In the connector H, switching relay 109, upon energizing over the above traced circuit, closes a locking circuit for itself at armature 145; applies direct ground to test wiper 150 at armature 144; disconnects rotary magnet 112 and slow-acting relay 108 from the operating circuit at armature 140 connects up the line wipers at armatures 143 and 148; and at armature 147 connects the lower Windin of ringing relay 201 to wiper 151 by way or.

arrmiture 136 and its resting contact. When the pick-up conductor 252 is grounded by the constantly rotating arm of the interrupter 1 coming into engagement with its contact 218, an energizing circuit is closed for ringing relay 201 as follows: from ground by way of the arm of interrupter I, piclr-up conductor 252, corresponding conductor of jumper 101, bank contact 155, wiper 151, working contact of armature 14'? and said armature, resting contact of armature 136 and said armature, and the lower winding of relay 201 to battery. Relay 201, upon energizing, prepares a locking circuit for its upper winding at armature 232, and at armatures 203 and 204 shifts the connection of the line Wipers from battery and ground locally to the two Eventually, the arm of the interrupter I moves off the pick-up segment 218 and is entirely on the ringing segment 219, thereby removing ground from pick-up conductor 252 so as to prevent any ringing relays from energizing thereover until the arm of the interrupter I reaches that pick-up position again.

As a further result of the above mentioned energization of relay 213, the common ringing lead-215 is disconnected from battery and is connected to the right hand winding of the transformer T, which is connected to battery also, and on which ringing current is superimposed by the generator GEN. through the medium of the left hand winding of the transformer T. When this occurs,

the ringer at substation A and the other ringer at substation A which is connected from the top or negative talking conductor to ground, are operated in the usual manner.

Eventually, the arm of the interrupter I comes into engagement with the locking segment 220, thereby placing a multipled ground on the locking conductor 217 so as to maintain the said locking conductor grounded after the deenergization of relay 213, which occurs subsequently. After an interval, the arm of interrupter I passes out of engagement with the segment 219 and is wholly in engagement with the locking seg- ;ment 220. l Jhen this occurs, relay 213 deenergizes; removes ground from the lockin conductor. 217 at its right hand armature, leaving the said conductor grounded by Way of the locking segment 220 of the interrupter .I; and at its left hand armature shifts the common ringing conductor 215 back to direct battery again, thereby terminating the first ring. 1

vWhen the arm of the interrupter I comes into engagement with ringing segment 221, Which is multipled with the ringing segment 219 as shown, the circuit of relay 213 is again closed, and the second ringing is effected upon the ringing lead 215 being shifted to the right hand winding of the transformer T again. The locking conductor 217 is maintained grounded at the right hand armature of relay 213, While said relay 213 is energized.

WVhen the arm of the-interrupter I passes off the segment 221 and comes into engagement with the dead segment, relay 213 deenergizes and terminates the second ring by disconnecting lead 215 from the right hand winding 01' the ringing current transformer T at its left hand armature. Also, relay 213 disconnects ground from the locking conductor 217 at its right hand armature, thereby opening the locking circuit of relay 201, whereupon relay 201 deenergizes; opens a still further point in its locking circuit at armature 232 and at armatures 203 and 204: disconnects the line wipers of the connector from the ringing leads 215 and 216, and connects them to battery and ground locally. The dead segment 222 is placed between the segment 221 and the following pick-up'segment, to give suliicient time for relay 213 to deenergize and remove the ringing current from the lead 215 before the following pickup conductor 251 is grounded.

The arm of the interrupter I continues to rotate without producing any particular re sult so far as the connection in question is concerned, until the pick-up segment 218 as sociated with pick-up conductor 252 is again grounded. "When this occurs, the above described ringing operations are repeated.

When the subscriber at substation A responds to the ringing of his bell by removing his receiver, a direct current bridge is closed across the conductors of his line,

whereupon the ring cut-off relay 106 of the connector I-I energizes; extends the line Wipers to the battery feed impedance 102 at its upper and lower 'armatures; and at armature 136 disconnects the lowerwinding of relay'201 from the pick-up wiper 151. The calling and called subscribers may now converse with each other in the usual man- -ner.

At the end of the ensuing conversation, the two subscribers replace their receivers. The replacing of the receiver at the called substation does not produce any particular result, except that battery merely stops flowing over the called line.

When the receiver is replaced at substation A, the circuit of line relay 101 is opened and relay 101 deenergizes. Upon armature 128 being retracted, the circuit of release relay 103 is opened and a circuit is prepared for release magnet 110. Upon deenergizing in reslow-acting release relay 103 removes ground from armature 138 of relay 107 at armature 130; disconnects ground from release trunk conductor 7 5' at armature 129, whereupon relays 106 and 109 deenergize; and at armature 131 completes a circuit for release magnet 110 by Way of off normal contacts 113. Upon the energization of release magnet-110, the wipers of the connector H are restored to normal position, and the circuit of release magnet 110 is opened at off-normal contacts 113 by the switch shalt when the wipers reach their normal position.

As a result of the ground potentialbeing removed from release trunk conductor 75, switching relay 13 of the line switch G, switching relay of the selector E, and the corresponding relay (not shown) of the selector E decnergize. The deenergization or switching relay 13 of the line switch 0 restores conditions in that switch to normal. lhe deenergization of switching relay of the selector E results in a circuit being closed for release magnet l6 at armature and its resting contact. This circuit includes armatures 52 and 5% and their resting contacts and off-normal contacts Q9. The wipers of the selector E are restored to normal position in the usual manner upon the energization or" release magnet 46, and the circuit of iQlGtLf-ld magnet 4L6 is again opened at off normal contacts 49 when the switch wipers reach their normal DOSltiOIl. The selector E is restored to normal in a similar manner.

From the foregoing description it is that the subscriber at substation A is s1 1. also. 1 no subscriber at this substation, however is i structed to respond to the one bell rings only, and the pick-up conductor 251. associated witlr his line so that heis signalled during the ringing period which follows immediately after the arm of the interru gter 1 has passed over the dead contact 229/, at which time-relay 214-is energized. lf'his relay 21 i is energized during the entire perioe, and not droppedbaclr at the middle of theperiod, as is the relay 213, thereby giving one long ring instead of two short ones.

The'other ringing periods are used tosignal subscribers such the subscribers at substations A and I3}, whose ringers are connected between the positive side of the line and ground. This is done in exactly the same way as described, except that the ringing cur comes from the middle winding of the tra n former T and is projected over the lower or positive line conductor instead of the upper one.

It is evident, then, that a station on a party line can be signalled by either one or two rings applied to either side of the line and that ii code used or the side to which the ringing current is applied is not at all associated wi h the number of the called station. lit can be seen in connectionwith l 2, that it the number of. the substation A. is to be assigned to a diiiierent station on account of the sub scriber at substation A moving or for some other like reason, the station to which that number is assigned can be signalled by either code applied to either side of the line by merenreneiv 1y placing the jumper 161 on the correct set of contacts of the idler block associated with the line in question.

Attention is also directed to tne fact that since some of the stations are signalled by two bells, that is, one ring following imme diately after the preceding ring, it has been found necessary to provide only a momentary pick-up at the beginning of each ringing period, the ringing relays being held up by a locking conductor which remains grounded Letters Patent will be specifically stated in the appended claims.

What is claimed is:

1. In: a telephone system, a link circuit, line having a plurality of stations thereon, means for associating said link circuit with said line, means operating in a'cycle for associ ringing current with said linlr circuit, said cycle being divided into as many ringing periods there are stations on saidline, each of said periods corresponding toa particular one of said stations, means for projecting-said ringing current out onsaid line by way oi" said link circuit only during-the rin ing period corresponding to the desired station, and means for starting said projection of ringing current out on said line only at the beginning of a ringing period.

2. in a party line telephone system, a link circuit, a party line having a plurality of stations thereon, means for associating said link circuit with said party line, means continuously operating in successive cycles for'associating ringing current with said link circuit, ea h cycle being divided into as many ringing periods as there are stations on said line, each of said periods corresponding to a particular one of said stations,a relay individual-to said link circuit, means for operating said relay only the beginning ofthe ringing period corresponding to the desired station, ineans 1 for maintaining said relay operated only during said period, and means controlled by said relay tor propectmg said ringing current out on said line each time said relay is ope ated.

8. In a selective ringing party line telephone syst-ein, a signalling circuit, a relav for connecting said circuit to a called party line,

and a ringing machine for periodically alter ing the character oi" said circuit to' adapt the same for signalling all the stations on saidline in turn, said machine also comprising means for energizing said relay only at the begmnmgof the period when the said circuit is of such a character that it will signal the wanted station.

l. in a selectiveringing party line telephone system, a signalling circuit, a relay for connecting said circuit to a called party line, a ringing machine for periodically altering the character or" said circuit to adapt the same for signalling all the stations on said line in turn, said machine also comprising means for energizing said relay only at the beginning or the period when the said circuit is of such a character that it will signal the wanted station, and separate means for maintaining said relay energized during the elapse of said period.

5. In a telephone system, a party line, a connector switch, means for operating said switch to connect with said line, two common signalling conductors, one for each side of said line, means for applying signalling current alternately to said conductors, a signal connected to one side of said line, and means for connecting said common conductors to said line only during the time that ringing current applied to that common conductor corresponding to the side 01 the line to which said signal is connected.

6. In a telephone system, a party line, a station on said line, a connector switch, means for operating said switch to connect with said line, two common signalling conductors, one for each side of said line, means for applying signalling cu rent to said conductor alternately, a signal at said station connected to one side of said line, means for connecting said common conductors to said line only during the time that ringing current is applied to the common signalling conductor correspending to the side of the line to which said 1 signal is connected, and means operative responsive to the subscriber at said station answering said signal for rendering said last connecting means ineffective.

7. In a selective ringing party line telephone system, means for extending a connection to a called party line, a plurality of ringcontrol conductors one of which is select ed when the connection is established, each control conductor corresponding to a different station on said line, two common signalling conductors, means for applying code ringing current to each signaling conductor alternately, and means controlled over the selected control. conductor for connecting said common signalling conductors to the called line only when theproper code of ringing current is applied to the proper signalling conduct-or to signal the desired station on said line.

8. In a selective ringing party line tele phone system, means forextending a connection to a called parry line, a plurality of ringing control conductors one of which is selected when the connection is established, each control conductor corresponding to a difierent station on said line, two common signalling conductors, means for applying code ringing current to each signalling conductor alternately, a relay for connecting said signalling conductors to the called line, means for energizing said relay only at the beginning of the application of the proper code of ringing current to the proper signalling conductor to signal the desired station on said line, and means for maintaining said relay energized during the application of said code to said signalling conductor.

9. In a telephone system, a connector, a called party line, a plurality of branches of said line accessible from the connector, code signalling mechanism for applying signalling current to the called line in a predetermined series of alternate live and dead periods, automatically applied means for causing the signalling current to beapplied to the called line only at the starting of the first live period of the next series responsive to the operation of the connector in effecting connective relation with the called line regardless of the time said operation occurs, and automatically applied means for causing a specific said code series of signalling current to be applied to the called line in corre- 5 spondence with the branch of the called line the connector is operated into connective relation with so that a different code series of signalling current will be applied to the called line depending upon what branch of the called line is connected with.

'10. In a telephone system, a connector, a called party line, a plurality of branches of said line accessible from the connector, code signalling mechanism for applying signalling current to the called line in a predetermined series of non-uniform alternate live and dead periods, automatically applied means for causing the signalling current to be applied. to the called line only at the starting of the first live period of the next series responsive to the operation of the connector in effecting connective relation with the called line regardless of the time said operation occurs, and automatically applied means for causing a specific said code series of signalling current to be applied to the called line in correspondence with the branch of the called line the connector is operated into connective relation with so that a different code series of signalling current will be applied to the called line depending upon what branch of the called line is connected with.

11. In a telephone system, a connector, a called party line, a plurality of branches of said line accessible from the connector, code signalling mechanism for applying signalling current of any one of a plurality of differently effective characters to the called line in a predetermined series of alternate live and dead periods, automatically applied means for causing the signalling current to be applied to the called line only at the starting of the first live period of the next series responsive to the operation of the connector in effecting connective relation with the called lineregardless of the time said operation occurs, and automatically applied means for causing a. specific said code series of specific said character of current to be applied to the called line in. correspondence with the branch of the called line the connector is operated into connective relation with sothat a different code series of signalling current of a specific said character will be applied to the called line depending upon which branch of the called line is connected with.

12. In an automatic telephone system, a connector, a plurality of lines accessible from the connector, a source of signalling current. a busy-test terminal for each line, a terminal specific to each line for controlling the application of said source of signalling current to its companion line in a specific manner, a wiper of the connector cooperative with the respective said specific terminals when a ran- 1 dom said line companion thereto is connected to by the connector, relay mechanism opera tive to prepare a signalling current path to the connected line, and means controlled over said specific terminal of the connected line 1 to operate the relay mechanism.

13. In an automatic telephone system, a connector, a plurality of lines accessible from the connector, a source of signalling current having intermittent live periods and a ter- .minal therefor specific to each said line for controlling the application of said source of signalling current to its companion line in a specific manner, a wiper of the connector cooperative With the respective said terminals when a random said line companion thereto is connected to by the connector, relay meclianism operative to prepare a signal circuit path to the connected line, and means controlled over the said specific terminal of the connected line to operate the relay mechanism only at a predetern'iined time with correspondence to the requirement ofsaid specific manner.

In witness whereof, I hereunto subscribe my name this 26th day of January, A. D. 1926.

RODNEY G. RICHARDSON.

In witness whereof, I hereunto subscribe my name this 26th day of January, A. D. 1926.

JOHN l. BELLAMY.

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