US1738302A - Telephone system - Google Patents

Description

Dec. 3, .1929. A. KRECEK I1,738,302

TELEPHONE SYSTEM t/Usey A. /f/ece/f.

Dec. 3, 1929. J. A. kREcEK 1,738,302

TELEPHONE SYSTEM Filed Aug. 28, 1926 '7 Sheets-Sheet 2 Dec. 3, 1929. J. A. KRECEK 1,738,302

TELEPHONE SYSTEM Filed Aug. 28, 1926 7 Sheets-Sheet 3 llll mgm.

//7|/e/7/0/f Josep/7A. ece/r.

Dec. 3, 1929. J. A. KREcl-:K 1,738,302

TELEPHONE SYSTEM Filed Aug. 28, 1926 'T Sheets-Sheet 4 '7 Sheets-Sheet 6 IPH Dec. 3, 1929.

J. A. KR'ECEK TELEPHONE SYSTEM Filed Aug. 28, 1926 '7 Sheets-Sheet '7 056% @Ce 714/ ,4f/y

Patented Dec. 3, 1929 N UgNiTsn STATES PATENT OFFICE JOSEPH .A. KRECEK, OF BROOKLYN, NEW YORK, ASSIGNOR T0 BELL TELEPHONE LABORATORIES, INCORPORATED, 0F `NEW YORK, N. Y., A CORPORATION OF NEW YORK Application filed August 28, 1926. Serial No. 132,105.

This invention relates to telephone eX- change` switching systems, and more particularly to the automatic selection of speech amplifying and repeating apparatus and the insertion ot the same in toll connections.

l-lferetoi-ore systems such as those disclosed in the Patent l`lo.\1,6417,796, issued to L. L. Glezen, S. P. Shackleton and E. Vroon, November 1, 1927, and the application of E. Vroom and F. S. Entz, Serial No. 129,682, tiled Aug. 17, 1926, have been designed -'or the selection of repeaters and the inclusion oi the same in toll lines. In, general the arrangements in these systems are such that the automatic actions are started on the interconnection of two linesby` means ot a cord circuit. An idle repeater is first selected and then connected between the two lines by means of various kinds ot switching apparatus.

The present invention is embodied in an arrangement in which one end ot an automatically selected repeater is connected, by means or' an individual line linder, with the call originating line, while a trunk finder individual to the called line operates to select the other end of the repeater, thereby effecting an interconnection of an idle repeater between these two lines.

Furthermore the present invention contemplates a grouping ot the toll lines and repeaters such that the repeaters of any group serve, not only for toll connections involving two lines in their own group, but for connections involving one line in their own group and another line in any other group.

ln large exchanges, tollline tra'liic may be conveniently arranged so `that certain groups of lines will always be answered by certain groups of cords. Taking advantage `oi `this arrangement, the system of grouping in accordance with this invention is such that each group of cords will have a definite group of repeaters assigned to it. Each repeater is connected at its incoming end with a line finder having direct access to all theV lines in the group that may be answered by cords having access to the `corresponding group of repeaters. `On the other hand, the outgoing end of each repeater in each group may be reached by having the lines in each group individually terminating in a trunk inder having access to a plurality of trunks that are common to the trunk finders for each group of lines. Each of these trunks terminates in a repeater finder having access to all or' the repeaters of all groups.

It should be understood that the expression cincoming or outgoing end of a repeater is merely used for convenience in distinguishing between the two ends of repeaters from which connections are made to lines or to which connections are made trom lines and does `not roter to the transmission character- Fig. 2 shows an incoming line and its as-` sociated trunk linder.`

Fig. 3 shows a repeater finder in which a trunk from the trunk finder shown in Fig. 2

terminates and a line finder having access to the incoming line shown in F ig. 2.

Figs. 4 and 5 illustrate a cord circuit ofthe group serving the group of lines of which the line shown in Fig. 2 is one and the associated repeater selector and a repeater,the repeater being merelyy indicated by means of an enclosure. These two iigures also show various common circuits and switching arrangements tor preventing more than one interconnection ot toll lines from taking place at any one time, this common equipnfient being similar to the equipments for the same purpose shown in the above mentioned copending applications.

6 illustrates the incoming end of another line .requiring the addition of a repeater and the associated trunk selector, while Fig. 7 illustrates a repeater finder as- 40 u tween'two'linesin these groups to include a I sociated with a trunk from the trunk finder shown in Fig. 6, and a line finder` having access to the group of lines over which the line shown Ain Fig. 6 is one.

Fig. 8 shows lthe arrangement of the various-drawings forming part of this applical be divided into groups two of which 1 and 2 of one `hundred lines each have been indicated. Each of these groups of lines may be answered by a group ofcords, the group 3 being used for answering calls incoming over lines in groupV l and the group 4 being yused for callsincoming over the linesof group 2. The cor-ds in A'group 3 yare each provided with av repeater selector,such as 5 and 6 having v"access to repeaters, such as'7 and 8, of a group of approximately twenty repeaters. The incoming ends of these repeaters terminate inline finders, such as 9.and 10 having access'to all of the lines in group 1. The cord circuits of group 4 are each provided with a repeater selector, suchas 12 and 13 havingaccess toprepeaters, such as 14 and 15 of a groupof approximately twenty repeaters. The incoming ends of these repeat- ,"e'is are connected to line finders, such as 16 and17"`1having access tov all of the lines in group 2. ,y Each of the lines in groups 1 and 2 is provided with a trunk finder, such as 20,

in21, l22` and 23. Each of these trunk finders -'ha-s'access to approximately twenty trunks terminating in repeater finders, such as 25, 26,127 and28, all'of which have access to the outgoing ends of'all of Vtheforty repeaters in thetwo groups shown. A .connection berepeater, may bel established by inserting for example ithe left-hand end of a'vplug from a cord in group 3 into a ack of a line of group 'l and inserting the right-hand plug of said cord into a jack of a line of either group 1 .orgroup 2 depending on where the wanted line is located. The connection of two lines in this manner ywill. cause an idle repeater to be Iselected by a repeater selector, such as 5 or 6, rVhen this selectionV has taken place a line finder, such as 9 or 10, associated with the incoming end of the selected repeater finds the calling line and connects it to the selected repeater. A trunk finder of a wanted line 'their selects an idle trunk and the repeater finderV connected to the selected idle trunk the outgoing end of the selected repeater. Aconnectioniwill now be established, for example,y as follows: From a line in group 1 through a line finder, such as 9, a repeater,

such. as 7, a repeater finder, such as 25, a trunk "finder,l such as 20, and the associated line in grou 1 or from the repeater 7 through a repeater, nder, such as 27, a trunk finder,

such as 22, and the associated line in group 2. lVlien this connection is completed the talking conductors of the cord circuit employed are opened and a talking connection through the repeater is established.

Referring now to Figs- 2 to the-general scheme of.l interconnecting toll lines and inserting repeaters into these connections in accordance with this invention will be .outlined as follows :"Letit be assumed that the toll line A is to be connected through anrepeater with the toll line B and that cord circuit C is to be used for the establishing of this connection. In accordance with wellknown practice, a call incominof over line A causes a lam such as 200, to l.be lighted at the toll boar s. An operator having charge of cord circuits, such 'as C, in answering this call inserts plug 400 into jack 201 and operates the talking key 401 to connect her telephone set to line A for the purposeof communicating with the operator 'at the distant end to ascertain the destination of'the desired connection. After having received the desired information, the operator inserts plug 403 intojack 600 of line B and restores the talking key 401.

As both lines A and B'require the inclusion of a repeater, these lines have special electrical characteristics in their sleeve circuits that will initiate, whcn the toll lines are connected to the cord circuit, automatic operations for the insertion of the repeater inthe connection. For this purpose, there is provided a so-called lockout selector switch or cord finder, one of which is indicated at D. Each cord finder is common to a group of cords. The cord finder D will now start to find the cord C and when found, the cord finder remains associated `with the cord until the operations for inserting the repeater in the connection are completed. This is in order to prevent any other ycord circuit in this group from starting its operations until cord C is released. `As soon as cord finder D finds the cord circuit C, operations are started to actuate lthe secondary lockout circuit or position finder indicated at E. This finder is common to all groups of cords in the system. The position finder E remains associated with the cord circuit C until the complete sequence ofoperations for the insertion of the repeater into the connection has been effected and functions to prevent any other cord circuit in any other group from starting theselection of a repeater until the cord circuit C has completed its functions in this respect. The actuation of the position finder takes place immediately, provided no other cord in the system is going through the'process of inserting a repeater in a connection. The reason for the provision of a cord finder for each group of cords and aposition' finder for all the groups of cords in the system is to insure thatlonly one connection-of a repeater between two toll lines may take place at any one time. In order however not to delay the connection ot repeaters any longer than is necessary, the cord finders oi the ditferent groups ot cords may operate to iind cords interconnecting toll lines independently and simultaneously and prepare the associated circuits to the point where the common position iinder begins to operate to permit one cord circuit at a time to complete the repeater selecting and connecting tunctions.

@nce the cord circuit C has assumed control over the position iinder E, it starts its repeater selector indicated at F to huntior repeater. Une repeater' has been indicated at Gr merely by means of an enclosure with all the leads from the line finder connected to the incoming end ot the repeater and with all the leads trom the repeater linders having access to the outgoing end ot the repeater and all the leads from the repeater selector F shown leading into this enclosure. As the repeater itself forms no part of the invention and as any repeater oi.l any well-l-.nown type may be used, it is thought that this representation will be suilicient. The repeater selectors and cord iinder switching units may be ot any well-known type having a series ot' terminal banks with the brushes arranged to travel thereover in steps under the control oit stepping mechanisms. These selectors and iinders have no home positions.

l'lvlhen the repeater selector F finds an idle iter, certain electrical conditions are esshed i'or the sleeve circuits of lines A and ll to cause these lines to be connected together through the selected repeater. First,4 the line ri is connected through the line l'inder "il to the incoming end oi'repcater G and then line B is connected through the trunlf; Ender l and a repeater finder, such as lil. to the outgoing end oi repeater G. In addition to line finder H tor linding line A, there has also been shown a line finder L individual to this line A and a repeater finder lil, the brushes ot which are connected through a trunlr terminating in the banks of the line linder la. This repeater finder having access to the outgoingl ends of all of the repeaters in the various groups, it should be note? that a similar showing has been made 'for line B, that is, a line finder N from the incoming end ot a repeater has been shown. This line finder has access to the group in which the line B .is located. This showing has been made in order to clearly bring out the tact that these lines can be reached through switches, such as H or N, and may iind the outgoing ends oll repeaters through such switches as L and M or l. and lli. The construction ci the trunk finders L and l may be oi any well-lrnown type having a series ot terminal banlrs with brushes arranged to travel thereover in steps under control of stepping magnet mechanisms. These selectors have no home positions. The construction ot the repeater finders M and K and line iinders H and N may be of any well-known Strowger type, having terminal banks arranged in horizontal layers with brushes traveling in a vertical followed by a horizontal step-by-step movement.

As soon as the lines have been connected with the repeater, the cord finder and the position finder are released so that the cord linder becomes available :tor other cords in the group to which the cord C belongs and so that the position iinder becomes available for this or any other group of cords. Cin cuit changes will now take place to separate the two lines from the cord C and connect them to the repeater in the manner above mentioned, and at the same time, connect the networks N1 and N2 to balance the lines and also to remove certain short circuits in the selected repeater to make it operative. Transmission may then take place through the repeater while the connection through the cord circuit is opened. i

Arrangements are also made whereby when the talking lrey of the cord circuit is operated, the repeater is cut out from the connection, which under these circumstances will extend through the cord circuit. Monitoring lreys are also provided whereby connections from the repeater to the operators telephone may be established through the repeaterselector.

It either one ofthe plugs of cord C is witlidrawn from the line jack, the repeater is released from the connection. The repeater selector brushes, the cord iinder brushes, and the trunk linder brushes will remain in the position in which theywere last used, while the line inder and repeater finder are returned to normal position. The sleeve circuit ot the line still connected to the cord remains in busy condition until both plugs are removed, when the entire equipment is re stored to normal condition.

For the purpose of providing for failure ol any part oi'l the system during the establishing oit a connection involving a repeater, the time alarm circuit indicated by T is used. Each connection is allowed a certain time, tor example, ve seconds in which to be completed. It completed within this tmc, the time alarm circuit is restored to normal, but it it is not completed in the allotted time, the time alarm circuit functions to give an alarm indicating which cord circuit is involved and also to cause the release of the cord finder involved to allow connections through another cord to take place. Cord circuits, such as C, are also arranged for interconnecting ordinary toll lines that do notl require addition of repeaters. However, the invention is essentially concerned with the inclusion ot repeat ers in toll line connections and the following ycuitfor the lighting of lamp 200. The operator at C answers this call by inserting the plug 400 into jack 201 and by connecting her 210 and 402'.

telephone set through cord C to line A for the purpose of communicating with the operator at the distant end of the line A to ascertain` thedestination of the desired connection. The vfirst effect after the insertion of plug V400 into jack 201 and before key 401 is operated will be the. extinguishing of lamp 200.Y Afcircuit is completed through 4the 'sleeve terminals of jack 201 and plug 400 as follows: Battery, Winding of relay 402, righthand winding of relay 404, left-hand armatureand back Contact of relay 405, sleeve terminals of plug 400 and `jack 201, left-hand winding of marginalrelay 210 to ground. This circuit causes the operation ofrelays Thek `operation of relay 210 ycloses an obvious circuit for the relay 211, whichV in turn, closes an obvious circuit for relay 212. The operation of relay 212 opens the original energizing circuit for relay 210 Yand closes at its left-hand armature and front contact a'connection from the sleeve `through ythe right-hand windings of relays 211 and :210 in series jto ground, thus holding these two relays operated. The operation ofrelay 212 also closes an obvious circuit for the operation ofv relay 207, which in operating, opensy the holding circuit for relay 206 and 'also the circuit for relay 205. Relay 206 in f releasing causes the lamp200 to be extinguis'hed.

When relay 402 operatesa circuit is closed for the operation `of relay V406 as follows: Battery, winding of relay 406, right-hand armature and back contact of relay 404, lefthandV armature and front contact of relay 402 to ground. Relay 406 provides a locking-,circuit for itself `directly through its left-hand armaturer and front contact to the ground at the left-handarmature and front contact of relay 402, independent of the original .energizing circuitthrough the armature and back Contact of relay 404. Relay'404` being marginal does not operate as long as the sleeve circuit extends through the left-hand winding of marginal relay 210. As

soon as the sleeve circuit is changed to extend` through the right-hand windings of relays 211, andt2l0A in. series, 1 the resistance of the 1.

circuit is changed, as the resistance of the right-hand windings of relays 211 and 210 is low as compared with the resistance of the left-hand winding of relay 210. Hence, when relay 212 operates, this change in the resistance of thel sleeve circuit causes relay 404 to operatefto open the original energizing cirlcuit for relay 406. The operation of relay 402 closes a circuit for the operation of relay 407 as follows: Battery, winding of relay 407, armature and back Contact of relay 408, left-hand make-before-break contact of relay 410, right-hand armature and front contact of relay 402 to ground. It should be noted that this circuit extends through armature and back contact of relay 407 to the winding of relay 412 and battery, but as relay 412 is slow in operating as compared with relay 407, it Will not have time to operate before the circuit for this relay is broken by the operation of relay 407. The non-operation of relay 412 prevents relay 413 from operating and consequently prevents the lighting of lamps 415.

The operator will now actuate the talking key 401 to associate her telephone set with cord circuit C. After ascertaining from the operator at the distant end of toll line A the destination of the desired connection, the operator will now insert the plug 403 into jack 600 of line B. rlhe eiiect of this connection is similar to the eifect of inserting plug 400 into j ack 201. That is, a circuit is completed from battery, winding of relays 418, 420 and 421 in series, armature and back contact of relay 422, sleeve terminals of plug 403 and jack 600, makebefore-break contacts of relay 612, right-hand winding of marginal relay 610 to ground. The immediate eli'ect of this circuit will be to cause the operation of relays 420 and 610. The operation of relay 420 causes an obvious circuit to be closed for the operation of relay 423, which relav, in operating, closes a locking circuit for itself through its rifrht-hand armature and front contact directly to the ground at the righthand armature and front contact of relay 420. The operation of relay 610 closes an obvious circuit for the operation of relay 611, and relay 611, in operating, closes an obvious circuit for the operation of relay 612. Relay 612, in operating, opens at its make-beforebreali contacts the circuit through the righthand winding of relay (310 and extends the sleeve circuit, through the right-hand armature and front contact of relay 612, through the left-hand windings of relays 611 and 610 in series to ground. The resistance of the circuit through these windings is low as compared with the resistance of the right-hand winding of relay 610, so that on the operation of relay 612, the resistance characteristics of the sleeve circuit change to cause the relays 418 and 421 to operate. The operation of relay'421 causes the original energizing circuit for relay 423 to be opened and the operation of relay 418 closes an obvious circuit for the operation of relay 425 to transfer the relay 426 to a diiferent bridge circuit across the talking conductors of the cord circuit C for establishing conditions relating to the supervision of the connection as will hereinafter become apparent. The operation of relay 420 also closes an obvious circuit for theoperation of relay 428, which relay in operating closes a locking circuit for itself through the inner left-hand armature and front contact of relay 423, outer right-hand armature and back contact of relay 429, inner right-hand armature and front contact of relay 406 to ground. Relay 423 closes through the tip conductor to the tip terminals of plug 403 and jack 600 of cord circuit C.

The cord finder D will now be actuated to lind the cord C. The terminal of cord circuit C on bank 501 will be marked by the absence of battery as it will be seen that the operation of relays 406 and 423 removes battery connections to this terminal. The starting magnet 500 for cord linder D will also start to operate the brushes of the cord finder D over a circuitas follows; Battery, from relays corresponding to relays 406, 410 and 423 of idle or busy cords, through the corresponding` terminals and brush of bank 501, winding of stepping magnet 500, through its armature and back contact, through the left-hand armature and back contact of relay 503 of the position finder E, righthand armature and hack contact of relay 431, inner left-hand armature and front contact of relay 423, outer right-hand armature and back contact of relay 429, inner righthand armature and front contact of relay 406 to ground. As the stepping magnet 500 breaks its own circuit, it will continue to operate until the terminal of the bank 501 from which battery has been removed is found. This terminal is associated, as stated, with the cord circuit C and when the stepping magnet stops its operation, relay 502 will operate. Relay 502 has a high resistance winding and operates in series with the stepping magnet without causing the stepping magnet to operate.

Relay 502, in operating, locks through a resistance 505 and its left-hand armature and front contact to ground and remains in this condition until it is released, as will hereinafter be described. The operation of relay 502 closes a circuit for the operation of relay 510 as follows: Battery, through the inner left-hand armatures and back contacts of relays corresponding to relay 503 that are individual to other groups of cords in the position finder E, through the winding of relay 510, right-hand armature and front contact of relay 502 to ground. Relays 510 and 503 of the position finder are individual to the group of cord circuits of which cord C is one. The individual relays, for each group of cord circuits, corresponding to relays 510 and 503 are connected in a manner similar to these relays. Two sets of such relays is shown to the left of the two relays individual to this group of cord circuits. On the operation of relay 510 an obvious circuit is closed for relay 503 which by operating its lefthand armature opens the connection for the stepping magnet 500. Thus no other cord in this group can cause cord iinder D to operate until the release of cord circuit C in the manner to be hereinafter described. Similarly, the operation of relay 510 by attracting its armature removes ground normally connected in a chain circuit through the armatures of other relays corresponding to relay 510 in other groups so that none of the relays corresponding to relay 503 can be operated while relay 510 is actuated. Connections from cord circuits in. other groups are therefore prevented from going through the position finder until the functions of the cord circuit C are completed.

0n the operation of relay 503 a circuit is closed for relay 512 as follows: Battery, winding of relay 512, inner right-hand armature and front contact of relay 503, righthand armature and front contact of relay 502 to ground. The operation of relay 503 closes a circuit to battery through bank 513, through the cord circuit C to cause the operation of the repeater finder F. This circuit inaybe traced as follows: Battery, inner left-hand armature and back contact of relay 514, outer right-hand armature and front contact of relay 503, winding of relay 515, brush and a selected terminal of bank 513, winding and armature and back contact of stepping magnet 516 of the repeater finder F, left-hand armature and back contact of relay 431 to the brush of bank 519 of the repeater finder F. If the brushes of the repeater finder happen to rest on the terminals of a busy repeater, which is indicated by the fact that a ground is connected to a corresponding terminal of bank 519, the stepping magnet 516 will start to operate and advance the brushes of repeater finder F until an idle repeater is found which is indicated by the absence of ground on the correspondingterminal of bank 519, or as in this case, the presence of battery on this terminal. In other words, if a busy repeater is encountered, ground will be connected through brush 519 to a corresponding multiple contact of the repeater finder connected to the busy repeater. This ground will be supplied from the left-hand armature and front Contact of the relay corresponding to relay 431 in the engaged cord circuits. lt will be noted that a circuit is established for relay 431 at the same time that a circuit is established for relay 515. The circuit for relay 431 may be traced as and'back contact of relay 514, outer right-- hand armature and front VContact of Vrelay 503, outerlet-hand armature and front contact of relay 512,- armature and back contact of Vrelay 515, to brush and corresponding terminal of banlr 520, left-hand winding 'of relay 531v to ground. Relay 515 in the above mentioned circuit is a fast operating relay as compared to relay 431 which is slow to operate. The operation of relay 515 will thereforeY prevent relay 431 from operating at this/time although a circuit for relay 431 is completed through the armature and back contact of relay 515. The

stepping-magnet 516 will continue to operate until an idle repeater is found, that is, one that has no ground on its multiple terminal of the bank 519. This circuit through the relay '515 andthe stepping magnet 516 willtherefore be opened, that is, when no ground is found on the corresponding ter- `Ininal of bank 519 the release of relay 515 and the stopping ot magnet 516 takes place, so that thebrushes of the repeater finder F `:v'villnow rest on the terminals of the first idle repeater. When this takes place, the previously traced circuit for relay 431 will fbe Ycompleted throughthe armature and back contact of relay 515 so that relay 431 vwill-now `be energized and apply ground to its' left-hand armature and front contact Dthrough'the brush 519, thus making the repeater G busy to other cord circuits.

l Relay 431, in operating, provides a locking circuit tor itself through its right-hand Varmature'andiifront contact, left inner contactv and armature "of relay 423, right outer normal contact and armature of relay 429, to the ground at the inner right-hand armature and front contact of relay 406. The operation of relay 431 also closes a circuit for the voperation of relay 405 as Jfollows: Battery,fwinding oi relay 405, right-hand armature and front contact of relay 431 to 'the'ground at theinner right-hand armature A,and front contact of relay/406. The opera- 'tion of relay 405 byopening the connection through `its lefthand armature and back Contact forthe sleeve circuit for plug` 400 andjaclr 201 causes a resistance 432 to be inserteclin the'sleeve circuit. The eti'ect of the insertion of this resistance is that the marginal relay 210 will be released. Relay 210 Ain releasing closes a circuit for the operation of relay 215 as follows: Battery, winding of relay 215, right-hand armature and back contactof relay 210, armature and front contact 'of relay 211 to ground. The operation ot relayf215 closes aconnection to ground at its innerleft-handarmature and front contact of line finder H -is operated over a circuit as follows: Battery, winding of relay 300, a terminal and the brush of banlr 519, letthand armature and front contact ot relay 431 to ground. The operation of this relay and relay 215 above mentioned will therefore close a circuit for the operation ot relay 217 as follows Battery, outer lett-hand armature and front Contact et relay 300, outer leftiand armature and back contact of relay 518, middle left-hand armature and front contact o'l' relay 215, outer right-hand armature and back contact ci relay 218, lett-hand winding of relay 217, make-beiore-break contacts oi this relay, make-betorc-break contacts ot relay 218, inner left-hand armature and front contact of relay 215 to ground. The opera` tion oit relay 217 opens the circuit from ground at the inner left-hand armature and Tt'ront Contact ot relay 215 through the makebetore-brealr contacts oi' relay 217 and extends this circuit through the inner righthand armature and Jiront contact and the right-hand winding of relay 217 to battery to lock relay 217 under the control of relay 215. While a circuit is partially completed for relay 218 on the operation oit relay 215 this relay 218 will not operate due to the fact that line A is the call originating line. It will bc expiained in the description relating to the association of lines B with the outgoing end ot the repeater G how a relay corresponding to relay 218, namely relay (518, in the circuit for line B will be operated, while a relay 617 in this circuit corresponding to relay 217 in. the circuit tor line A will not be operated due to the tact that line B is the wanted line. Thus, by the operation and non-operation of these relays, discrimination between an incoming line and an outgoing line is determined. rlhe operation of relay 217 closes a circuit for relay 220 as follows: Battery, winding of relay 220, left-hand armature and back Contact ot relay 221, outer left-hand armature and iront contact ot relay 217 to ground. Relay 220 is common to all of the lines of the group of which line A is one that terminate in the same level of line inder H as line A. The operation of relay 220 by closing its armature and front contact to battery will mark the level of line iinder H in which line A is located.

Upon the operation of relay 300 an obvious circuit is closed for the operation of relay 301. rlhe operation ot relay 301 closes the circuit 'tor the operation et relay 303 as tollows: Battery, winding` ot relay 303, armature and back contacts of vertical magnet 305 and rotary magnet 300, right-hand armature and front contact of relay 301, armature and bach Contact of relay 307, rigli`l1and armature and 'front contactof relay 300 to ground. The operation of relay 303 closes a circuit for the operation of the vertical magnet 305 as follows: Battery,

armature and front contact of relay 303, lefthand armature and hack contact ot relay 3011, Winding et Vertical magnet 805, armature and leach contactot relay 307 and righthand armature and liront Contact of relay 300 to ground. As the vertical magnet 305 operates the circuit for relay 303 is opened. The release et relay 303 opens the circuit for the vertical magnet which in releasing again closes the circuit for relay 303 to reoperate the Vertical magnet 305. Thus the alternate operation and release of vertical magnet 305 causes the brushes of switch l-l to travel in a vertical direction until the brush 310 linds the terminal 311 Which marks by a battery from relay 220 the level in which the terminals oit line A are located. A circuit will noW be completed from the battery at the armature and iront contact ot relay 220, terminal 311, brush 310, left-hand Winding ol relay 304i, inner lett-hand armature and iront conA tact of relay 300, armatrn'e and haelt Contact of relay 307 to ground at the right-hand armature and front contact ot' relay 300.

The operation ot relay 30a opens the circuitcuit tor the Vertical magnet 305 which now ceases its operations and the circuit from battery at the armature and front contact of relay 303 is transferred to close the circuit tor the rotary magnet 306 as follows: Battery, armature and front contact of relay 303, letthand armature and front contact ot' relay 304:, Winding of rotary magnet 306, armature and hack contact et relay 307, right-hand armature and front contact ot rel ay 300 to ground; rllhe alternate operation and release of rotary magnet 306 and relay 303 take place in the same manner as during the operations of the vertical magnet 305. It Will loe noted that when the terminal 312 oit line A is reached hy the brush 314 ot finder H, battery Will loe supplied from the inner left-hand armature and front contact et relay 21',7 'lor the operaion or relay 307 over a circuit as follows: Battery, inner lett-hand armature and front contact of relay 217, Winding of relay 221, terminal 312, brush 314, right-hand Winding of relay 307 and upper vertical oil normal contacts 315 to ground. rlhis circuit causes the operation et relays 221 and 307. The operation oit relay 307 opens the energizing circuit for rotary magnet 300 and relay 303 causing the brushes ot iinder H to stop on the terminals of line A. Relay 307 is locked up to the ground at the right-hand armature and front contact of relay 300 over the armature and front Contact ot relay 307. The operation of relay 307 also closes a circuit tor the operation of relay 308 as :fellows: Battery, Winding of relay 308, armature and trent contact et relay 30? to ground at the right-hand armature and iront contact of relay 300. The operation et relay 308 closes the connection between the conductors from line A through to the incoming end of repeater Gr. A circuit ture and front contact et relay 221, lett-hand armature and haelt contact of relay 226, upper Winding of relay 224 to ground. rlhe operation or' relay 224 applies ringing current from source 228 to the conductors of line A leading te the incoming end of the repeater G through the armatures and trout contacts ot this relay and the armatures and iront contacts ot relay .229. It should he noted that relay 220 Was operated upon the operation oi' relay 217 over a circuit as follows: Battery, Winding of relay 229, inner rightehand armature and front contact ot relay 217, inake-beiore-hrealr con tact et relay 218, inner lett-hand armature and trent contact of relay 215 to ground. The purpose oi applying ringing current to the conductors troni line A to the incoming end of repeater G is to burn out the terminals and hrush connections between the line finder H and the conductors oit line A.

Relay 518 in operating closes a circuit for the operation of relay 122 as follows: Battery, inner righthand armature andlront Contact ot relay 518, brush and a terminal ot haul; 582, middle right-hand armature and trent contact el' relay 405, Winding of relay L122 to ground. Relay 1-22 in operating @langes the resistance characteristics of the sleeve circuit Yfor plug` 403 and ack 600 which causes the marginal relay @l0 to release. The release ot relay 610 causes a circuit to he closed 'for the operation of relay 615 as follows: Battery, winding of relay G15, lefthand armature and haelt contact o1 relay 610, armature and trent contact ol relay 611 to ground. The operation of relay 615 closes a circuit for the operation of relay 018 as tollows: Battery, outer right-hand armature and front contact ot relay 01.8, outer lett-hand armature and back contact oi relay 514, outer right-hand armature and trent contact ot re lay 615, rightehand winding ot relay 618, outer lett-hand armature and hack contact and inalre-hetore-hrealr contacts ot relay 617, malte-hefore-break Contact of relay 618, inner right-hand armature and front Contact oit re lay G15 to groundy Relay 61S in operating closes a locking circuit for itself through its lett-hand Winding and inner lett-hand armature and liront contact to the ground at the' .inner right-hand armature and trent contact of relayll. A circuit may new he Closed by the operation oit relay 618 for the operation et the stepping" magnet 631 in series with the relay 032 lor the operation of the trunk selector l.

Vll)

Ifl the brushes of this selector are resting on lterminals'vof'a busy trunk the stepping magnet 631 will operate and a circuit will be closed for this magnet and the relay 632 as -follows: From battery, inner right-hand armature and front contact of relay 618, winding, armature and back contact of steppingmagnet 631, winding ot relay 632, righthand armature and back contact of relay 633 brush o'fbank 640 of switch I to the terminal ofthe busy trunk at this bank and a corresponding brushv of a busy trunk selector such as I, to ground at the right-hand armature and front contact of a relay of the busyjline corresponding to relay 633 ot this line. .It will be noted-that a circuit is also closed'by the operation of relay 618 for relay 633 from battery through the winding of rey Y lay 633 through the armature and back contact of relay 632 to ground at the outer righthand armature and front Contact 0f relay 618. But as relay 632 is faster in operating than relay 633 the circuit for this latter relay will be opened as long as relay 632 is operated and stepping magnet 631 is alternately operated to advance the brushes of switch I until they come in contact with the terminals of an idle trunk. At this time the brush of bank 640 encounters battery on the corresponding terminal and consequently relay 632 and magnet 631 will be released. lVhen this takes place the above mentioned circuit for relay 633 is completed and this reay will. now operate to apply at its right-hand armature and front contact a ground to make t-he selected trunk busy to other trunk finders such as I. The release of relay 632 closes a circuit for the operation of relay 624 over a circuit as follows: Battery, lower winding of relay 624, left-hand armature and back contact of relay 626, armature and back contact of relay 632 'to ground at the outer right-hand armature and front contact of relay 618. Relay-624 in operating applies ringing current'from source 628 to the conductors of line B leading through switch I the selected brush and switch K to the outgoing end of the repeater jack to burn out the contacts of these switches as is well known in the art.

It should be understood, however, that the vresponding terminal and the brush of bank 640 of switch I, left-hand armature and front contactofrelay 633 to ground. The operation of relay 700 closes a circuit i'or the operation of relay 703 as follows: Battery winding of relayl 703 armatures and back contacts of vertical magnet 705 and rotary magnet 706,

armature and back contact of relay 7 07, lefthand armature and front contact of relay 700 to ground. The operation ot relay 703 provides, by the operation of its armature, battery for the operation of the vertical magnet 705 as follows: Battery, armature and il'ront contact oit' relay 703, right-hand armature and back contact ot relay 704, winding of vertical magnet 7 05, right-hand armature and front contact of relay 700, armature and back contact ot relay 707, lett-hand armature and front contact of relay 700 to ground. The operation 01' vertical magnet 705opens the circuit for relay 703 which in releasing opens the circuit for the vertical magnet 7 05. Thus this relay 703 and vertical magnet 705 will alternately operate and release to advance the brushes of repeater finder K to tl e horizontal level in which the terminals of the outgoing end oi' repeater G are located. It will be noted that this level is marked by a battery applied from the armature and front contact of relay 525 to terminal 711. Hence, when the brush 710 finds this terminal a circuit is closed for the operation ot relay 704 as follows: Battery, armature and ilront contact of relay 525, terminal 711, brush 710, right-hand winding of relay 704, armature and back Contact of relay 707, left-hand armature and front contact of relay 700 to ground. Relay 704 in operating transfers the battery at the armature and front contact of relay 703 from the vertical magnet to the rotary magnet.

The circuit tor the rotary magnet may be traced from this battery, right-hand armature and front contact of relay 704, winding ot rotary magnet 706, ri glit-hand armature and front contact of relay 700, armature and back contact of relay 707, lefthand armature and front contact of relay 700 to ground. Relay 703 and rotary magnet 706 will now alternately operate and release until the brushes ot repeater iinder K lind the outgoing terminals of repeater Gr. It will be noted that terminal 712 has been marked by a battery on the operation of relay 518 so that when brush 714 finds this terminal a. circuit is completed for the operation of relays 707 and 514 as follows: Battery, middle right-hand armature and front contact of relay 518, winding of relay 514, terminal 712, brush 714, lcft-hand winding of relay 707, vertical oli' normal contacts 715 to ground. Relay 7 07 in operating opens the circuit for the rotary magnet 706 at its armature and back contact and closes through its armature and the corresponding front contact a locking circuit for itself to the ground at the left-liand armature and front Contact ot relay 7 00. A circuit is also completed by the operation of relay 707 for the operation. o1 relay 718 which joins the selected trunk conductors to the brushes of repeater finder K. At this time the ringing current 'from source 628 is passed through the brushes and terminals of switches I and K to burn them out.

Relay 514 in operating opens at its outer left-hand armature and back contact the "original energizing circuit for relay 618 Which, however,,remains operated as hereinbefore described. This relay also opens a circuit for relay 525 Which releases to remove the marking battery from the terminal 711. 1o

lt might be explained here that if during the vertical movements of the line finders H or K the marking of the terminals such as 311 or 711 should for some reason not be 'identified by the brushes 310 and 710, the vertical magnets 305 or 705 Would continue to step the brushes up until the 10th levelis reached which time relays 304 or 704 Would operate from `the battery supplied at the 10th level through brushes 310 or 710. ln this case the rotary magnets 300 or 706 Would opc'ate tostep the brusnes over the 10th leveluntil the 11th rotary step is reached for the operation of the 11th step rotary contacts or 7 28. `The operation of these contacts would cause the operation of release magnets 322 or 722 over obvious circuits so that these switches would be restored to their normal positions. In view of the fact that relays 300 `and 700 are still operated on the return of the switches to normal, thesvvitches will repeat their vertical and rotary operati ons until the brushes 310 or 710,1ind the mark-ed terminals 811 or 711 or until'the alarm circuit T functions to `restorethe connections to normal.

It should be noted that the operation of relay 514 also, by opening the connection through its inner left-hand armature and back contact, removes theconimon battery from the position finder E. The operation of relay 514 also closes a circuit to ground for the operation of relay 528 as follows: Battery, Winding ofrelay 528, inner right-hand armature and front contact of relay 514 to ground. However before relay 528 has time to operate a f 'circuit is completed through its malte-beforebreak contacts for the operation of relay 410 as follows: Battery, Winding of relay 410, right-hand make-before-brealr contacts of this relay, outer right-hand armature and front contact of relay 405, brush and the corresponding terminal of bank 536, malre-beforebreak contacts of relay 528 to the ground at the inner right-hand armature and front Contact i of relay 514. Relay 410 in operating provides a locking circuit for itself through its righthand armature and front Contact to the ground at the right-hand armature and front contact of` relay 406. While this ground from the inner right-hand armature and front Acontact of relay 514 is removed from the terminal and brush of banlr 530 at the makebefore-break contact of relay 528 when it operates, a substitute ground is provided for the A1brush ofrthis bank from the inner ri ght-hand armature and back Contact of relay 537 through the left-hand armature and front contact of relay 538 and this ground is novv applied, due to the operation of relay 410, to another circuit as will be hereinafter eX- plained. i

It should be noted that relay 410 in operating opens the circuit for relay 407 extending through its left-hand makebefore-break contacts and transfers this circuit through the outer left-hand armature and front contact to the ground connected at the inner righthand armature and baclr contact of relay 537. '.llhus the control of relay 407 is transferred to the repeater Gr for supervisory purposes. It Will-be noted that there is another connection to ground from the left-hand armature of relay 52S into the repeater G through the armatures and back contacts of the ringing relays 552 and 554. As relay 537 is operated, over a circuit which will hereinafter be traced, to insert a repeater in a connection by openmg its left-hand armature and back contact to remove the short-circuit across the repeater, the ground at the inner right-hand armature and baclr contact of relay 587 Will be removed. Hence the ground in the repeater will have control over the operation and release of relay 407. lf supervisory signals are incoming to the repeater G `from either line A or B to operate either of the ringing relays 552 and 554 this above mentioned ground Will be removed to cause the release of relay 407. Relay 407 in releasing Will permit the operation of relay 412 over an obvious circuit. Relay 412 in operating Will close an obvious circuit for the operation of relay 413 which in turn closes a circuit for lighting of lamp 415. Hence the operation ofrelay 528 transfers the supervisory control to the repeater from the cord circuit when the lines are connected through a repeater.

Another function performed by the operated relay 528is to close a circuit for the operation of relay 530 as follows: Battery, Winding of relay 530, make-before-break con tact of relay 529, right-hand armature and front contact of relay 528 to the ground at the inner rightfhand ar iat-ure and front contact of relay 514. Relay 530 in operating closes an obvious circuit for the operation of relay 531 Which in operating closes an obvious circuit for the operation of relay 529. Relay 529 in operating opens the circuit for relay 530 and relay 530 opens the circuit for relay 531. The relay 529 in operating closes a locling circuit through its right-hand armature and front contact to the ground at relay 514, so that this relay Will remain operated 'While relays 530 and 531 are released. This sequence of operation Will take a certain period of time sufficient for the ringing currents from sources 228 and 628 to burn out the brush and terminal contacts as hereinbefore described. On the release of relay 531 a connection Will be completed for the operaidc , A. It will nowvbe noted that the circuit from the ground at relay 406 will extend through Vtion Ofielay 537Vover a circuit as follows:

' Battery; i rightihand :winding of' may left-hand armature, andifront contact of' relay 529,`right`h`and armaturel and back contact of relay 531, a corresponding contact -andbrush ofbank 560, Yinner right-hand Y armature'and front Contact of relay 405,

right-hand Varmature and back contact of relay 412, lower normal springs of ringing keys 430,' upper inner right-hand normal contacts oftalking key 401, right-hand arma- Y ture vand front contact'ofrelay 410, inner left-hand armature'and front contact of relay 423, outer yright-hand armature and back Contact of relay 429, inner right-hand armature and front contact of relay 406, to ground.

Relay 53'! in operatingl opens, at its left-hand and outer'right-hand armatures and back contacts, the usual short-circuiting bridge for the repeater G making it operative and places lamp-415 under the controlv of relays 552'and 554 ashereinbefore described. The same'circuit that operated relay' 537 also extendsj through relays 435, 226 and 626. The circuit for relay 435 is obvious and this relay in operating connects the monitoring leads fromrepe'ater G to the talking and monitoringkey 401 so that if the operator desired to'monitor the connection she may actuate this key towards the left and thus connect her telephone set to the repeater. The circuit orrelay 226 may be traced as follows: Batl tery, middle Winding of relay 226terminal then to the groundat relay 406. Relay 226 in operating closes a locking circuit for itself through its left-hand winding, 'armature andfront contactv to the'battery at the right-,hand armature 'and front `Contact of relay 22,1, and by theoperation of this lethand'parmature the circuitgfor relay 224 is broken to releasel this relay and'remove theringingfcurrent from the conductor of lineI y outerjar'mature and back contact of relay 224k the winding of relay 230 through the upper so that Athis relay'230 will operate and discon-4 neet the lineA from the'tip Vand ring terminal of j ack 201 and connect it and a network N1 'through to the 'incoming end of'repeater `It seems unnecessary totrace the Vcircuit l romline Av and network N1 to the incoming end of. repeater G as it is clear from the drawing how this connection is completed.

On theoperation of relay 626 -a locking circuit is provided for this relay through its left-hand winding and left-hand armature and front contact through the armature and back contact of relay 632 to the ground at the outer right-hand armature and front contact of relay 618. It will be noted that on the operation ,of relay 626 the circuit for relay 624 is broken at the left-hand armature and back contact of this relay so that relay 624is released and removes ringing current from the conductors of line B leading to the outgoing end of the repeater G. When relay 624 releases the circuit from ground at relay 406 is extended through the upper outer armature and back contact of this relay 624 through the winding of relay 630 which now operates. This relay in operating disconnects the line B from the tip and ring conductors of jack 600 and extends it and the associated network N2 through the trunk sclector I and the repeater finder K to the outgoing end of repeater G. As this connection from toll line B to the outgoing end of rcpeater G is also clearly traceable on the drawing it seems unnecessary to specifically describe it. A transmission connection is now therefore completed from line A to B that includes a repeater and conversation over this connection may now begin.

As the toll lines A and Bare now connected through the repeater G it is no longer necessary to prevent other cord circuits in other groups for establishing connections. 1t will be noted that on the operation of relay 410, battery was connected at the inner lefthandarmature and front contact of this relay to the corresponding terminal and brush of bank 501 and this has the effect of shunting the winding of relay 502 to cause the release of this relay. Relay 502 in releasing causes the release of relay 510 which in turn causes the release of relay 503 and the release of relays 502 and 503 causes the release of relay 512. By the release of relays 510 and 5,03 other cord circuits in this group or cord circuits in any other group that have been associated with corresponding cord' finders, will be permitted to extend the connections through the relays corresponding to relays 510 and 503 of the position finder E. It should be understood that only one cord cir@ cuit at the time will be permitted to complete a connection.

The time alarm circuit T operates as follows: On the operation of relay 5.12 a circuit is provided for the operation of stepping magnet 540 as follows: Battery, outer right-hand armature and back contact ofrelay 541, armature and back; contact and winding of stepping magnet 540, outer left-hand armature and back contact of relay 541, inner right-hand armature and front contact of rery. en).

lay 512 to ground. l/Vhen the stepping magnet 540 operates to move the brushes ot banks 542 `and 543 one step, the brush of bank 542 connects with the first terminal which is connected to ground. rlhis causes a circuit to be closed for relay 541 as follows: Battery, outer righthand armature and front contact ot relay 512, winding of relay 541, makebefore-break contacts of relay 541, winding of stepping magnet to ground at the strapped terminals of bank 542. Relay 541 locks up t-o ground at the inner right-hand armature and iront contact of relay 512 through its inner right-hand armature and 'iront contact. Relay 541 in operating opens the original energizing circuit for magnet 540 and provides a circuit for the operation of relay 544 through interrupter 545. Relay 544 in operating closes a secondary circuit for the operation of stepping magnet 540 as follows: Battery, outer right-hand armature and trent contact of relay 541, armature and front contact oit relay 544, winding of stepping magnet 540, brush ot bank 542 to ground. at the bank terminals. The interruptor 545 causes relay 544 to be intermittently operated to apply battery over its armature and front contact to the circuit for the stepping magnet 540. The stepping `magnet 540 consequently is alterw nately operated and released to advance the brushes of banks 542 and 543 step-byfstep under control of interrupter 545. H this condition prevails for a certain period, for example, 5 seconds, the brushes will have been advanced to a predetermined position. An alarm will then be given and the position finder and cord .tinder will be released to prevent holding up the system. It, :tor example, `'for some reason the system has failed to function in this period the brush of the bank 543 will be advanced to terminal 546. In this position ground from the inner lett-hand armature and front contact of relay 541 will be connected through terminal 546, inner lefthand armature and front contact of relay 512, the brush of bank 548 through the winding et relay 429 to battery. Relay 429 operates and locks under control of the key 437 and causes the release of the position inder E as it places battery from its inner right-hand armature and front contact on the brush et bank 501 to release relay 502 and thus cause the release of relays 510, 503 and 512 in succession to release the position finder E as hcreinbetore described. rllhe operation of relay 429 also closes a circuit at its outer letthand armature and liront contact from battery through lamp 433 to ground through the winding of relay 434. Lamp 433 lights and indicates to the operator that the circuit has failed to function properly and the operation ot relay 434 closes a circuit for an alarm circuit 436 Which is common to the oiiice in which the toll operator is located. The operation ol' key 437 restores the circuit to normal condition. Assuming however, that the repeater is inserted in the connection within the allotted time, the time alarm circuit will not function `to give an alarm due to the re lease of relay 512. Relay 512 in releasing at the proper `time causes the release of relay 541 y which closes a` circuit from battery through stepping magnet 540 to ground on the-terminals oit bank 542. The brushes of banks 542 and 543 are thus advanced to the nekt position marked by terminals 546 or 547. Since relay 541 has been released the alarm circuitcannot be established in these terminal positions. When the brush of bank 542 arrives at the terminals 549 or 550 no ground is iound on these terminals and contequently the stepping magnet 540 will step withthe brushes in either oit these positions.

In case all ot the repeaters are busy battery through bank 513 of the cord iinder such as D, will not be available as all relays such as 514,"will be actuated. However, battery through thewinding ot relay 551 of the common meter circuit R will be available. The resistance ot the Winding oi: relay 551 will prevent relays, such as 431 and the stepping magnet 51` from becoming operated but will allow the operation otrelay 551 as `follows: Battery, winding of relay 551, outer righthand armature and front contact ot a relay such as 503, outer lett-hand armature and back contact of a relay such as 512, armature and back Contact of a relay such as 515, a bank such as 520, Winding of a relay such as 431 to ground. The operation of relay 551 causes the operation of a meter` magnet 553 over a circuit as follows: Battery, winding of meter magnet 553, armature and front Contact oi' relay 551, through the contact 546 or 547 of the time circuit when the brush 543 is advanced to this point and to ground at the inner lett-hand armature and front contact of relay 541. Thus the operation oit meter magnet 553 indicates the number of times repeaters were required and not available. It should be understood that it a repeater becomes idle betere the timing device operates the circuit arrangement is such that this repeater will be selected in they manner as hereinbei'ore described.`

Iii' the operator has occasion to actuate the talking key 401, after repeater' G has been connected with lines A and B relays 230, 630 and 53'? `will be released. The release of relay 537 short-circuits the bridging points ot the repeater G and the release of relays 23() and 630, disconnects lines A and B and the respective networks N1 and N2 from the repeater G and connects them through the cord circuit and to the operators telephone set.

In case supervisory signals come in while the repeater is inserted between lines A or B either the ringingrelay 552 or 554 is operated to remove the ground applied through the left-hand armature and trent contact of l relay 528 to relay 407 which in releasing causes the lighting of lamp 415.

When vfor example, plug 400, is removed from toll line A thecircuit connections will be restored to normal. That is, in line A relays 211 and 21.2 release to cause the release of relays 215 and 207 which in turnl causes AVthe krelease' of relays 217, 221 and 226. In the cord cireuitthe release of. relays 404, 402 and 40.6causes the opening of the cemmon holding ground through the vinner right-hand armature and front contact of relay 406. Hence all the relays in the circuits that are held operated from this ground may be released. It should be noted that on the release 'of relay 431, relay 300 of switch H is released to cause lthe return of this switch to normal.

VOn the release of relay 300 a ground is connectedfat.itswright-hand armature Aand back cont-act for the operation ot release magnet 322. On the releaseof relay 307, relay 518 vis released thus causing the release of relay 514. The release of relay 514 causes the re-V lease of relays528 and 529. The release of relayl 5158 also causes therelease of relay 422 whichv in turn causes the operation of relay 610. Relay y610,,inoperating releases relay 615,. Relay. 6.15 causes the release of relay l618 and this relay causes the release of relay 633.. The release of relay 633 causes the release` of. relay 700 which permits the operationofthe release magnet 722, which nowreturns switch K to normal position.

vAlthough the present invention has been illustrated and described particularly in connection with toll systems it may be applied to switchingisystems-not operated on the toll basis.

What is claimed ist:

1L In .atelephone system, lines, repeaters arranged for interconnection between two ot said, lines, means Vfor designating said. two lines, means to designate ka repeater for selection, line selecting apparatus individual to isaid repeaters, repeater selecting appa-V ratus individual to' saidy lines, 'and means for actuating line select-ing apparatusfln response Vto the designation of a repeater and repeater the one end ot saidvrepeater to a line and for controlling the repeater selecting apparatus ot another line to connect said other line to the other end of said repeater.

3. In a telephone system, lines, repeaters arranged tor interconnection between two of said lines, cord circuits, line selecting apparatus individual to said repeaters, repeater selecting apparatus individual to said lines, and means responsive to the connection of a cord circuit between two of said lines for controlling the line selecting apparatus of a. repeater to connect one end of said repeater te one ot said lines, and tor controlling the repeater .selecting apparatus of another line to connect said other line to the other end of said repeater.

4. In a telephone system, lines, repeaters arranged for interconnection between two of said lines, cord circuits, line selectors individual to said repeaters, repeater selectors individual to said lines, and means responsive to thc connection of one of said cord circuits between two of said lines for controlling the line selecting apparatus ot a repeater to connect one end ot said repeater to said first mentioned line and for controlling the repeater selecting apparatus of said second mentioned line to connect such line to the other end oit said repeater.

In a telephone system., lines, repeaters arranged tor interconnection between two of said lines, line selecting apparatus comprising a line lindcr switch associated with one end ot each repeater for finding a line and connecting it with the corresponding repeater, rpeater selecting apparatus comprising a trunk finder switch associated with each line, a .plurality of trunks selectable by any one ot said trunk finders and a repeater finder switch associated with each of said trunks having access to the other end of any one ot said repeaters, means for controlling the' line finder switch of a repeater to find one ot'said lines and connect it to said repeater, and .means tor controlling the trunk linder of anotherV line to iind an idle trunk and connect it to said other line and for controlling the' repeater finder associated with the selected idle trunk te lind said repeater and connect said trunk therewith.

6. In a telephone system, groups of lines, groups ot' repeaters, means to designate a repeater in a particular group tor selection, line selecting apparatus associated with each repeater, the line selecting apparatus of each repeaterhaving access to a certain group of lines, repeater selecting apparatus individual to said lines and having access to any one of the repeaters in any one of the groups, and means for controlling the line selecting apparatus ot' a designated repeater to select a line in the assigned group and for controlling the repeater selecting apparatus ot' any one rot the lines in any of they groups to select connection to any line in any of the groups,

a group of repeaters assigned to each group ol cords, line selecting apparatus associated with each repeater, the line selecting appa-` paratus of the other line to connect said other line to said repeater.

8. In a telephone system, groups of lines, a group of cord circuits for each group of lines arranged ler answering calls from the associated group of lines and tor extending a connection to any line in any ot' the groups, a group of repeaters assigned to each group of cords, line selecting apparatus associated with each repeater, the line selecting appaiatus of the repeaters in each group having access to the corresponding group ot lines, a group of repeater selecting appa-j ratus assigned to each group ot lines having accessto any one of the repeaters in any group, means responsive to the connection of a cord circuit between a calling line and another line for actuating the line selecting apparatus of a repeater assigned to the group of cords to which the connected cord circuit belongs to connect said repeater with the calling line and for actuating the repeater selecting apparatus of the other line to connect said other line to said repeater, and means responsive to the connection oi' said repeater between said two lines for opening the connection between said two lines established by said cord circuit.

9. In a telephone system, groups of lines, a group of cord circuits for each group ot lines arranged for answering calls from the associated group of lines and i'or extending connections to any of the lines in any of the groups, a group of repeaters assigned to each group of cord circuit-s, line selecting apparatus associated with each repeater, the line selecting apparatus of the repeaters in each group having access to the lines answerable by a particular group of cord circuits, repeater selecting apparatus comprising a trunk iinder for each line, trunks each connected at one end withstationary terminals of a plurality ot said trunk inders, repeater linder switches having movable brushes connected to the other end of said trunks and stationary terminals connected to the repeaters of all groups, all of said repeater finders thus having `gfaccess to any repeater in any group, means responsive to the connection of a @0rd circuit between a calling line and another line for selecting an idle repeater in the group associated with the calling line for actuating the corresponding line nder, -to find the calling line and connect it to the selected repeater and means -tor acuating the tiniilr finder et the other line to select an idle trunlr to actuate the associated repeater iinder to iind the selected repeater and connect it to said other line,

10.` In a telephone system, incoming lines, outgoing lines, groups of repeaters, a line linder for each repeater for finding an incoming line over which a call has been initiated, a repeater iinder for connecting an outgoing line to a repeater of any group, and

`means for actuating a line finder and a repeater `iiiider for interconnecting an idle repeater between an incoming and an outgoing line.

ll. In a telephone system, incoming lines, outgoing lines, groups of repeaters, means to designate a repeater in one of said groups ior use between said lines, a line finder associated with the designated repeater for iinding the incoming line, a repeater iinder associated with the outgoing line for finding the designated repeater, and means for actuating said line finder and repeater finder thereby connecting said designated repeater bec tween said incoming and outgoing lines.

12. In a telephone system, incoming and outgoing lines, said lines varying in transinission characteristics, automatically operable. means to distinguish the character of an incoming` and an outgoing line to deterniine whether the addition of a repeater is required, line selecting apparatus individual to said repeaters, repeater selecting apparatus individual to said lines, and means responsive to said distinguishing means for actuating the line selecting apparatus of a repeater and the repeater selecting apparatus of a line to interconnect said repeater between said incoming and outgoing lines.

13. In a telephone system, lines arranged for incoming or outgoing telephone traino, repeaters arranged for interconnection between an incoming and an outgoing line, line selecting apparatus for said repeaters operable for selecting lines used for incoming traliic, repeater selecting apparatus for said lines operable when a line is used for outgoing traffic, and means for actuating the line selecting apparatus of a repeater and a repeater selecting apparatus of a line to interconnect said repeater between an incoming and an outgoing line.

14. In a telephone system, lines, repeaters arranged for interconnection between a line over which a call is initiated and a line to which said call is extended, line selecting apparatus :tor one end of said repeaters for selecting a line over which a call is initiated, repeater selecting apparatus associated with

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