US1509691A - Multioffice telephone system - Google Patents

Description

Sept. 23 1924.

1,509,691 R. G. RICHARDSON MULTIOFFICE TELEPHONE SYSTEM Ofiginal Filed 'July 19. 1920 5 Sheets-Sheet l Sept. 23 1924e 1,509,691 R. G. RICHARDSON MULTIOFFICE TELEPHONE SYSTEM original Filed July 19. 1920 5 sheets-sheet 2 sept. 23, 1924. 1,509,691

R. G. RICHARDSON MULTI OFFICE TELEPHONE SYSTEM Filed July 19. 19'20 sept. 2s, 1924. 1,509,691

R. G. RICHARDSON MULTI OFFI CE TELEPHONE SYSTEM Original Filed July 19. 1920 5 Sheets-Sheet 4 Sept. 23 1924.

R. G. `FzICI-mmlsow K MULTIO'FFICE TELEPHONE SYSTEM Original Filed July 19. 1920 5 Sheets-Sheet 5 Patented sept 23, 1924.

UNITEDv STAT-as RODNEY G. RICHARDSON, OF HIAGO, ILLINOIS, .ASSIGNOR TO AUTOIILTIC ELEUIBIC .COMPANY, OIF CHICAGO', ILLINOIS, A CORPORATION OF PATENT OFFICE.

ILLINOIS.

MULTIOIFICE TELEPHONE SYSTEM'.

Original application led July 19, 1920, SerialNo. 397,322. Divided and this application Med December 8, 1923.

To all 'whom 1t-may concern.'

Be it known that I, RODNEY G. RICHARD- soN, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Multioiiice Telephone Systems, of which the following is a specification.

My inventionrelatesin general to multi- 1o oiiice telephone systems but more particularly to such systems as comprise in one network oilices or exchanges of two diierent kinds, the oilices of one kind being manual ofiices wherein connections are completed by operators, while the other kind of ollices are automatic offices in which connections are completed by means of automaticl switches,

and the object of the invention is to .providenew and improved circuit arrangements for handling inter-oiiice calls between the automatic and manual exchanges.

Systems having both kinds of exchanges as above pointed out are becoming `quite common and may arise either by consolidation of existing manual and automatic systems serving the same territory, or by the process of changing over a manual system to an automatic system. ,Usually the latter case only one oiiice at a tineQis-converted from manual to automatic.and-itffollows that during the period of! transition there will necessarily be both kinds of oiiices in operation. However this situation may arise, it is necessary to provide suitable circuit armanual oices to theautomatic offices, and from the automatic oiiices to the manual oiiices. The present invention is concerned only with the latter class of calls, and has to do with a system comprising automatic to manual trunks which are accessible to selector switches in the automatic oiiices and terminate in plugs in front of a B operator atrangements for handling calls from the4 Serial No. 678,193.

inter-oiiicetrunks terminating at auch position, and each trunk is provided with a rotary line or trunk selecting switch which has access to the call register sets. When a call is received on any trunk the line switch associated therewith operates ,automatically to select an idle register set, which is thus temporarily associated with the trunkin order to re ister the call when it comes'in. Although t ere are a. plurality of register sets there is butone indicating device per position and a special object of the invention is to provide an arrangement for testing the register sets in regular order for the purpose ofswitching registered calls on to tht-indicating device in regular order and one at a time. The means employed consists of an arrangement `of relays which I term a consecution controller. This device is adapted to testall register sets consecutively as long as any registered calls are waiting and switch such calls on to the indicating device as lstated. Although this type of consecution controller will test the register sets consecutively7 it does not insure that the calls will be switched over in the precise order that they are registered, for the calls may not come in to the register sets in any definite order. A further object, therefore, is to provide a consecution controller which will take care of this feature, that is, one which will switch the calls on to the indicating device in the exact order in whichthey are registered, without giving any call preference over another. Both types are shown and will be described fully hereinafter, reference being had to the accompanying drawings.

The relay consecution controller mentioned above is claimed in my co-pending application, Serial No; 397,322, iiled July 19, 1920, of which this application is a division. The claims of the instant case are di- .rected to the other type of consecution controller, the one which switches registered calls on to the indicating device in the exact order in which they are registered.

vIn the drawings, comprlsing Figs. 1 2

3, and 4, I have shown by means of the usual I i manual equipment are both well known and y of the usual type, no detailed description of the mechanical features of this apparatus will be given except in so far as 1t is found convenient or necessary to do so 1n the ex- 'planation ofthe operation of the circuits.\ Referring te Fig. 1, the substation A is one of a plurality of ordinary automatic substations terminating in the automatic exch previously referred to, and is provide with the usual talking uipment and ringer, and also with a calling evice of well known type which is indicated by the reference character S, through the medium of kwhich the subscriber controls the central office switches.

The line conductors 11 and 12 extend to the exchange where they terminatein the line switch C, which may be briefly described as a rotary line switch whose movable terminals or wipershave no normal position, and which have movement in a for- Ward direction only. The construction of a line switch of this type is well known in the art, and its function', also well understood, is to extend its associated line when calling to an idle trunk line. In carrying out this object, a plurality of these individual line switches are iven laccess to a group of trunk lines extending to first selector switches. One of the trunk lines to which the line switch C has-access is. shown in the drawing as extending to the first selector D, which is a vertical and rotary selector of the well known Strowger type. In a multi-oilice system of the kind herein contemplated the first selector switches are usually known as ofiice selectors and the selector D in com-` mon with a plurality of similar selectors has access to a plurality of groups of trunk lines each of which groups may extend to a diierent office or exchange in the system.

`Some of these groups of trunk lines may extend to automatic exchanges, while other groups may extend to manual exchanges. A trunk line in one of the latter groups is shown in the drawin and extends by way of the repeater E an trunk line conductors 130 and 131 to the plug ending cord circuit O, Fig. 2. The repeater E is an automatic impulse repeater of the general type in common use, and in addition to provisions for repeating operating impulses to the district manual exchange, provides holding circuits for the automatic switches, and thus renders it unnecessary to use more than two conductors for the interotlice trunk line. The cord circuit O is one of a plurality of smilar cord circuits' at a B operators position in the manual exchange and constitutes thebe connected b the operator with any one of the manual ines terminating in the manual exchange. One of these linegis'the line of substation A', which with its 'associated ine equipment is vshown at the right of rom the foregoing it will be understood that the operation of an oice selector, such as the selector D, in response to the calling of the first digit in the telephone number of a line in the manual excha'n e, will result in extending the connection rom the line of the calling automatic subscriber to an idle plug ending cord circuit` in the manual exchange. In order to take care of the remaining digits in the numbers there is rovided for each B operators position a plura 'ty of register sets, ashereinbefore stated,each set belng capable of registering all the digits in a: telephone number, with the exception of course, of the first digit, which controls the ofrice selector in the automatic exchange. In Figs. 3 and 4 I have shown one of these register sets complete. It comprises re ister switch R1, Fig. 3, and register switc es R2, R3, and R, Fig. 4. The register switch) R1 is a simple 10 point rotary switch, having the operatin magnet 306 and the release magnet 305. ipers 307 and 308 have a ste by step movement over their aocia banks of contacts under control of the operating magnet 306, and are restored to normal position by the release magnet 305. Register switch R1 resppnds to the second digit of the called num er and after it has operated transfers certain control circuits to ,register switch R2, which is thus prepared for operation in res onse to the third digit. Register switches R, and R are similar in construction to the register switch R1, and are actuated in response to the calling of the third, fourth, and fifth digits in a called number, respectively.

It will be understood that the number of register switches in the register sets may be changed at will to provide for any desired numbering s stem. As shown herein the registers R1, 2, R, and R* provide for registering a number havin four digits in addition `to the digit whlch operates the oflice selector. In case the numbers oontain one digit less than is contemplated above the register switch R may be omitted, and if they7 contain more digits rather than less, the necessary additional register switches may be inserted between register switches' R2 and R". In any case the number of register switches in a set will correspond to the number of digits in the line designationat the manual exchange. The function of the registers will be pointed out more fully in the detailed explanation,

llO

lao

Fi 3 the rst register switch of the sec? on register set. This register switch is indicated by reference character R", and is exactly like the register set R1. The means for switching registered calls on to the indicating device, or the consecution controller, is indicated by reference character N, Fig. 2. The connections between the different register sets and the consecution controller are made at the first register switches in each set, as shown in Figs. 2 and 3, and will be explained fully later on. v

In order to properly extend calls which are received at the manual exchange to the register ysets each cord circuit is provided with an individual rotary line switch as hereinbefore explained, and these line switches have common access to all the register sets, The reference character C', Fig. 3, indicates a rotary line switch which lis individual to the cord circuit O, Fig. 2, and

which has access to the first and second register sets shown, and also to the other register sets which are provided at the B operators position in which the cord circuit O terminates. Line switch C' is of the same construction as the line switch C, Fig. 1, although the circuits are modified somewhat in order to take care of the somewhat different requirements. l

The indicating device'by means of which called telephone numbers are shown to the B operator is shown in Fig. 4, where it is indicated by the reference character V. It comprises essentially a plurality of banks of' switchboard lamps, there being one bank of lamps for each register switch in a register set. It will be readily understood that the lamps have the function of illuminating the digits in the called numbers and causing them tc stand out so as to be readily distinguished. The digits are preferably marked in black on the reverse side of a white semi-transparent surface, and ordinarily are not ver conspicuous. But when titi the switchboard amp immediately behind any character or ligure is lighted, such character or hgure will stand out very clearly, and is read with great facility. ln view or the tact thatdhe connections are extremely simple they have not actually been drawn out, but will bel brieiiy explained as follows: lhe conductors 351 and 352, etc., which terminate in the ten bank contacts associated with the wiper 308 of the lirst register switch, are connected, respectively,v

to the lamps 1, 2, etc., et the rst digit group et lamps. The conductors 371, 372,

etc., which come from the ten bank contacts associated with wiper 366 of the registerswitch R2 are connected, respectively, with lamps 1, 2, etc., of the second .digit lamp group. .ln a similar manner the conductors coming from vthe banks of the register switches R3 and R4 are connected'to the lamps of the third and fourth digit groups lt should be stated furthermore that each groupr of lamps is not only connected to bank contacts in a certain re ister switch of the first set, but is multip ed to corre spending register switches in all the other register sets at the position.

Having described in a general way the lay-out of the system herein disclosed, the operation of the circuits will now be described more in detail, it being assumed for this purpose that the subscriber at substation A, Fig. 1, desires to obtain a connection with the manual subscriber at substation A. Fig. 2. For convenience it will be assumed that the telephonenumber of substation A 1s #23456. When the receiver is removed at substation A, a circuit is completed over .the line conductors 1l and l2 for the line relay 14 of the individual line switch C. Upon energizing, the line relay completes at its armature 2O a circuit which extends through the switching relay 13 and the stepping magnet 15 in series to battery, and at its armature 19 connects the test wiper 26 to the above circuit at a point midway between the switching relay and the said stepping l. magnet. The operation now depends upon whether the iirst selector trunk with which the wipers of the line switch are in connection is busy or is not busy. lf this trunk line 'is busy the testcontact 31 associated therewith will have a ground vpotential upon 105 inclusive, step by step in Search of an idle l1 trunk line. This operation will continue as long as the test wiper 26 continues to engage grounded or busy test contacts. However, we may assume that in the present case. when the test contact 3l therefore is not grounded. Under these circumstances, when the line relay 14 is energized the switching relay 13 is energized inmediately afterwards,

with the result that the line conductois 11 12 and 12 are disconnected from the winding of the line vrelay 11i and from ground, respectively, and are extended by way of armatures 16 and 18 and their working contacts,

, the call is initiated the selector l) is idle, and M5 wipers 25 and 27, bank contacts 30 and 32, 125

and armatures 60 and 62 and their resting contacts, to the upper and lower windings of the line relay 50 ci the selector D.

As soon as the line is extended to the selector D as above described, the line relay 50 130 the slow acting lrelease relay will be energized and will close the circuit of 51. Upon energizing, the latter relay prepares the circuits of the selector for operation in its vertical movement in the usual manner, and also completes a holding circuit extending back to the line switch C as follows: ground at G2, working contact of armature 63 and the said armature', conductor 64, bank contact 31, test wiper 26, armature 17 and its working contact, winding of the switching relay 13, and the winding of the stepping magnet 15 to battery. It isz/understood that the above holding circuit is completed before th'e slow acting relay 14 has had time to deenergize. In addition to maintaining the switching relay energized, the holding circuit also serves to provide ground to the multiples'of test contact 31 and also to the multiple test contacts in which the private normal conductor 28 terminates in the banks of the connectors which have access to the line of substation A, thereby guarding the connection against intrusion inthe, customary manner.

The calling subscribb'r may now operate his calling device in accordance with the first digit of the desired number. Two interruptions are thereby produced in the circuit of the line relay 50, and the said line relay is accordingly twice deenergized momentarily, transmitting at each deenergization an impulse of current through the slow acting series relay 52 and the vertical magnet 56 to battery. By the operation of the vertical magnet the selector shaft is raised two steps, whereupon the wipers 70-72, inclusive, will be standing opposite the level .of bank contacts in which are terminated the trunk lines extending to the manual exchange. The slow acting relay 52 is energized in series with the vertical magnet, retaining its armature attracted throughout the vertical movement of` the switch, and upon the closure of the vertical ofi normal springs 59 completes a circuit for the stepping relay 53. Upon energizing, relay 53prepares a circuit for the rotary magnet 54 at its lower armature, and at its upper armature establishes a locking circuit for itself. At the end of the vertical movement of the switch the slow-acting relay 52 is deenergized and closes the circuit of the test contact associated therewith will be grounded and the stepping relay 53 will be energized over a circuit way of the test wiper 71, armature 61 and its resting contact, interruptery contact of the rotary magnet, oli normal springs 59, and thrwinding of the stepping relay 53 to battery. The stepping relay will therefore again close the circuit of the rotary magnet 54 which will operate to rotate the switch wipers into engagement with the next set of bank contacts. This o eration in which the stepping relay and tie rotary ma are alternately energized and deenergized will continue as long as the test wiper 71 continues to engage grounded or bus test contacts. In the present case it will assumed that the trunk line shown in the drawings is the first idle trunk line, and when therefore the test wiper 7l arrives at test contact 74 and the rotary magnet is deenergized, thestepping rela 53 will not again be operated, but inste the switching relay 55, which heretofore has been shortcircuited, will be energized by current iiowing over the following path: grunded conductor 64, winding of the switching relay 55, interrupter contact of the rotary ma et 54, oii normal springs 59, and the win ing of the stepping relay 53 to batter Owing to the high resistance of the switc ing relay 55, stepping relay 53 is not operated. Upon ener izing, relay 55 disconnects the incoming ine conductors from the windings of the line relay 50 and extends them by way of armatures and 62 and their working contacts, wi ers and 72, bank contacts 73 and 75, trun conductors 76 and 78, and normally closed contacts of the reversing relay 100 to the upper and lower windings of the line relay 101 of the repeater E.

When the lineis extended to the repeater as above explained the line rela 101 is energized and closes a circuit of t e slow acting release relay 102. Upon energizing, relay 102 completes a holding circuit extended back to the selector D and line switch C as follows: ground at G3, armature 112 and its Working contact, conductor 77, test contact 74, test wiper 71, and the armature 61 and its working contact to conductor 64, where it joins the previously described holdrotary magnet, which is thereupon energized /ing circuit extending back to the line switch to advance the wipers 70-72, inclusive, into engagement with the first set of bank contacts in the level opposite which they were raise The rotary magnet 54 also breaks the locking circuit of the stepping relay 53 which accordingly deenergizes and breaks the circuit of the rotary ma net, which thereupon deenergizes also an again closes its interrupter contact. :The operation now depends upon whether the trunk line with which the wipers have connected is busy or is not busy. If this trunk line is busy the C. The above described circuit serves to maintain relays 55 and 13 energized throughoufI the duration of the connection.

In addition to closing the holding circuit for the automatic switches C and D, the relay 102 of the repeater E prepares a circuit at its armature 115 for the slow acting relay 103, closes a circuit atits armature 114 which energizes the polarizing winding of the electro-polarized relay 105, and at its armature 113 completes a bridge across the trunk conductors 130 and 131 which may be which extends by y A line switch C will take place. The switch-v traced over the following path: conductor 130, armature 113 and its working contact, armature 116 and its resting contact, upper winding of the electro-polarized relay 105, normally closed contact springs controlled by armature 107 of relay 100, right hand winding of the impedance coil 106, and armature 111 and its working contact to the conductor 131. By the closure of this bridge across the trunk line a circuit is completed for the double wound line relay 203 in the cord circuit O, and the said relay 203 is therefore operated. Upon energizing, relay 203 completes parallel energizing circuits for the slow acting relays 201 and 202. These relays are therefore energized at the same time and may be considered as one relay, but in view of the large number of contact springs it is advisable in practice to use two relays with the Contact springs divided between them. Relay 201 prepares a circuit for the reversing relay 204 at its armature 219, at its armature 216 connects direct ground to the lower winding of the line relay 203, and at its armature 239 prepares a circuit for the call signal lamp L?. Relay 202, which is energized in parallel with relay 201, as before stated, prepares at its armature 217 an o erating circuit for the register switches or? whichever set is later selected; and at its armature 218 closes an operating circuit for the individual line switch C? which extends as follows: ground at G4, resting contact of armature 215 and the said armature, working contact of armature 218 and the said armature, conductor 242, armature 256 and its resting contact, winding of the line relay 251, common conductor 451, and armature 456 and its resting Contact to battery. Upon the completion of the above circuit the line relay 251 is energized and at its armature 258 closes a circuit for the switching relay 250 in series with the stepping magnet 252. At the same time, at its armature 257, the line relay connects the. test wiper 262 with the above mentioned circuit at a pc-int midway between the switching relay and the said stepping magnet, whereupon a trunk selecting operation will take place similar to that which has already beenV described in the case of the individual line switch C. For the sake of simplicity it will be assumed that thel wipers of the line switch C" are already in connection with the bank contact set associated with the vfirst register set, Aas shown in the drawing, and it will-be assumed furthermore that this register set is idle. 1twill be evident therefore that test contact 266 will not be grounded, and no rotation of the ing relay 250 isat once energized and establishes a locking circuit for itself at its armature 255. Relay 250 also performs anumber of other circuit changes which may be mentioned briefly as follows: At armature 254 ground is connected to the test wiper 262 v wiper 261, bank contact 265, and the winding of relay 300 of the register switch R1 to battery. Upon the closure of its circuit relay 300 is operated and at its armature 309 disconnects ground from the common conductor 450, at its armature 311 disconnects ground from a releasing circuit extending over conductor 330 which will be described later on, and at armature 310 closes an operating or control circuit for the register switch R1 which will shortly be traced in full.

The apparatus is now ready for 'the reception of the series of impulses corresponding to the first digit in the local number of the called line in the manual exchange. 1t is understood, of course, that the first digit in the telephone number which operated the selector D at the automatic exchange has to do with the office selection only and does not appear in the multiple at the B operators position. When f the dial of the calling device S is operated in accordance with the next digit therefore another series of interruptions, three in this case, will be produced in the line circuit and will bring about a like series of deenergizations ofthe line relay 101 of the repeater El.,

At each deenergization relay 101 at its armature 110 sends an impulse of currentto the slow acting relay 103 which is energized at the first impulse and maintains its armature attracted while the repeater is repeating a series of impulses. 1n its energized position relay 103 completes a bridge across trunk conductors 130 and 131 over a direct path which may be traced by way of armature 113 and its working contact armature 116 and its working contact, and

armature 111 and its working contact to conductor 131. At the same time that the line relay sends impulses to the slow acting relay 103` it also roduces a series of interruptions in the bridge across the trunk conductors 130 and 131 by means of its armature 111. These interruptions cause the line relay 203 in the cord circuit U to be deyenergized a plurality of times, and at each deenergization the said relay transmits an impulse of current to the stepping magnet 306 of the register switch R1 over the following path: ground at G, armature 221 and its resting contact, working contact of armature??? and thesaid armature, conductor 243, armature 253 and its working contact, wiper 260, 4bank contact'264, armature 310 and its working contact, normally closed contact springs controlled by armature 312, winding of the slow acting relay 302, and the winding of the stepping magnet 306 to battery. Since three interruptions are produced by the calling device S, which were repeated as above described, the stepping magnet 306 willreceive three impulses of current and the wipers 307 and 308 will be rotated three steps and will come to rest in engagement with the thirdgcontacts in their respective banks. The opera.- tion of wiper 308 produces no -result at this time, but wiper 307 when. it I noves out of normal position. closes a circuit for the relay 301 which upon energizing changes the operating circuit so that it extends by way of the armature 310 and its working contact, working Contact of armature 312 and the said armature, armature 315 and its working contact (slow acting relay 302 being now energized), winding of relay 302, and the windin of the stepping magnet 3.06 to battery. Re ay 301 also prepares a circuit for the release magnet 305 at armature 313, and. at armature 314 connects ground to test contact 266 and its multiples in the banks of the other individual line switches. The latter operation is for the purpose of 'maintaining these test contacts grounded during the releasing operation in the register set, as will be pointed out more fully hereafter. The slow acting relay 302, which is energized in series with stepping magnet 306 and which remains in operated position while operating impulses are being received, deenergizes after the operation of the register switch R1 is completed and at its armature 315 extends the operating circuit t0 the next register switch R2 as follows: armature 315 and its resting contact. conductor 329, contact springs controlled by armature 369, winding of the slow acting relay 361, and the winding of the stepping magnet 364 to battery.

The apparatus is now ready to receive the next series of impulses. Then the calling device is operated again` this time 'in accordance with the digit 4, a series of four interruptions is produced in the circuit of the line relay 101 of the repeater E, which are repeated as before with the result that four impulses of current are transmitted to the stepping magnet 364 of register switch R2. In response to these impulses the stepping magnet 364 is operated to rotate the w'ipers 365 and 366 four steps, and the wi ers are brought to rest in engagement wit the fourth contacts in their respective banks. When the wiper 365 leaves its normal position a circuit is completed for relay 360 which, upon energizing, prepares a circuit for the release magnet 363 at its armature 367 and at its'armature 268 prepares the operating circuit for transfer to the next register switch by the slow acting relay 361. This latter relay is energized in series with the stepping magnet 364 while the said magnet is being operated and deenergizes at the end of the rotary movement as was described in the case of the slow acting relay 302 of register switch R. The slow acting relay 361 having decnergized, the operating circuit is extended to the register switch R as follows: conductor 329, working contact of armature 368 and the said armature, armature 369 and its resting contact, conductor 329", winding of the slow acting relay 381, and the winding of the stepping magnet 384 to battery.

The calling subscriber may now call the next digit in the number, which is the digit As aresult five operating impulses are transmitted to the step ing magnet 384 of the register switch R, y the operation of the stepping magnet 384, wipers 397 and 398 are rotated step by step until they come to rest in engagement with the fourth contacts in their respective banks. When the wiper 397 leaves its normal position a circuit is completed for the relay 380, which, upon energizing, changes the operating circuit at its armature 387, the same as was done in the case of the two register switches previously operated, and prepares a circuit for the releasemagnet 383 at its armature 386. The slow acting relay 381 is energized in series with the stepping magnet 384, remaining in operated position while impulses are being received, and at the end of thc operation of the register switch RP is deenergized, whereby the operation circuit is transferred to the register switch R us follows: conductor 3.20, working Contact of armature 387 and the said armature, armature 388 and its resting contact, conductor 329". contact springs controlled by armature 408, winding of the slow acting relay 401` and the stepping magnet 404 of the. register switch R4 to battery. VRegister R* is now ready for operation in response to the calling of the final digit.

The final digit to be culled is the digit 6 and when the calling subscriber operates his calling device in accordance with this digit six impulses of current are transmitted through the stepping magnet 404 of the register switch R4 over a circuit previously traced. and the said magnet is operated to advance the wipers 417 and 418 into engagement with the first contacts in their respective banks. When the wiper 417 leaves its normal position a circuit is completed for relay 402 which upon energizing prepares a circuit for release magnet 403 at its armature 406. changes the operating circuit in the usual manner at its armature 408 and re ares a circuit at its armature 409 which is closed later by armature-407 of relay 401 and which will 'be described hereinafter'. The slow act-ing' relay 401 is energized in series with the stepping magnet 404 of the registersvvitch R* and when it deenergi'zes at the end of the rotary movement of said switch a circuit is 'closed at its armature 407 which extends as follows: grounded conductor 419, working contact of armature 409 and the said armature, armature 407 and its resting Contact, conductor 328, and the Winding of the relay 500 to battery. A branch of the above circuig also extends by way of the pilot lamp L1 at the operators position to battery. When the above traced circuit is completed the pilot lamp L1 is illuminated to indicate that the register set associated therewith has a connection set upon it, and the relay 500 is energized.

Relay 500 is one of the relays ofthe consecution controller N. This device comprises a group of three relays, relays 500, 501, and 502, which are associated withthe first register set, and a similar group of three relays for each of the other register sets. These relay groups are interconnected as shown and control the switching of registered calls on to the indicating device V one at a time. For this purpose the consecution controller is adapted to test the register sets in regular order every time a connection is handled, and switch over the irst waiting icall encountered. The operations under various conditions will bc described shortly, but for the present it will be assumed that when the call now under consideration is registered there are no other calls waiting at the position, and no call on the indicating device, in which case the call will be switched o n to the indicating device at once. When relay 500 is energized by the grounding of conductor 328 as above explained, it closes a circuit for relay 501 as follows: ground at G20, resting contact of armature 514 and the said armature, conductor 512, winding of relay 501, working contact of armature 505 and the said armature, and resistance 503 to battery. At the same time that this circuit is closed the common conductor 513 is connected to the circuit at a point between the relay 501 and the resistance 503, but since there is no call on the indicating device conductor 513 will be clear of round and its connection to the circuit will have no effect. Relay 501 will therefore be energized. At its armature 506 relay 501 connects ground to common conductor 513 in order to prevent similar relays 521, 541, etc., from pulling up in case calls should be registered on the corresponding register sets, at armature 508 the loop circuit including conductor 512 is opened, and at armature 507 a circuit is closed which extends through the winding of slow acting relay 502 to conductor 327, and thence by way of relays 317, 362, 382, and 400 to battery. By the closure of this circuit relay 502 is energized and at its armature 509 lconnects ground to 'the loop circuit just beyond the open connection at armature 508 of relay 501. At the same time the circuit of relay 511 is closed at armature 510, and this relay is energized. Since the loop has been grounded at armature 509 of relay 502, however, the circuit of relay f 501v remains closed.

Rela over t e re iste-red call to the indicating lamps, and t e manner in which this is done will now be explained, it being recollected that the wipers of register sets BLR", inclusive, are now resting upon the third, fourth, fifth and sixth contacts in their respective banks. When conductor 327 is grounded through the winding of relay 502 as explained above, relaysm317, 362, 382, and 400 of the four register switches are energized. Each of these relays has the function of grounding a common strip in the bank of its associated switch, as shown in the drawing, and it will be clear therefore that when these relays are energized, the wipers-being operated as previously stated, conductors 353, 374, 395, and 426 will be grounded. These four conductors extend to the- #3 lamp of the first group, the #4 lamp of the second group, the #5 lamp of the third group, and the :#:6 lamp of the fourth group. The other side of all the lamps is connected to battery as shown in the drawing, and the lamps mentioned are accordingly illuminated and indicate to the operator the number 3456.

When the relay 400 of the register switch R4 is energized itl closes a circuit for the trunk or call signal uamp L7 in the cord circuit O over the following path: ground at GB, armature 405 and its working contact, conductor 331, bank contact 267, wiper 263, working contact of armature 269 and the said armature, conductor 241, resting contact of armature 212 and the said armature, working contact of amature 239 and the said armature, andthe lamp L7 to battery. The lamp L?, which is individual to the cord circuit O, is therefore lighted simultaneously with the lamps in the indieating device V and enables the operator to know which one of her cord circuits is bee ing used by the automatic subscriber whose wanted number is at this particular time being shown on the indicating device. Having observed the number 3456, and knowing by the lighting of the lamp L7 that the cord circuit O is the one in use, the operator will test the multiple jack of line 3456 with the tip of the plug in the usual manner to ascertain whether or not the line is busy. In case the line is busy 501 is the relay which switches the plug will be inserted in a busy jack of well known form and function. In order to give the calling subscriber a busy signal, the busy machine associated with the busy jacks at the B board is preferably of the .same type and giving the same kind of a busysignal as the busy machine in the autoniatic exchange, so that the calling subscribers will get uniform busy signals in all cases. Assuming, however, that the line of substation A is found to be idle, then the operator will insert the plug of cord circuit O in the multiple jack 3456, this being the jack J in which is terminated the line of substation A.

When the plug is inserted in the jack J a circuit is completed for the relay 208 in the cord circuit O as follows: ground atG, winding of the cut oli' relay 230 sleeve of the jack J, sleeve of the plug, and windin of relay 208 to the junction point 231, w ere the circuit divides, one branch extending by way of the supervisory lamp L? to battery, and the other branch extending by way of armature 220 ard its working contact, working contant of aimature 228 and the said armature (closed as soon as relay 208 energizes), armature 225 and its resting contact, contact springs controlled by armature 226, and the winding of relay 205 to battery. By current flow over the above circuit, relays 230 and 208 are energized in series, the former relay being effective to clear the line of substation A of its normal battery and ground connections, and the relay 208 being effective to disconnect the operators telephone set and close the upper talking strand of the cord circuit at armature 227. The lam L8 is lighted when the circuit is first 4close by the insertion of the plug, but "as soonl as the branch circuit through relay 205 is closed by the energization of lrelay 208 the lamp is extinguished bythe shunting of the current through this relay, which is of relatively low resistance. Relay 205 is the ringing relay, and is energized at this time to close at its armatures 223 and 224.- the usual automatic ringing or signalling circuit which includes the alternating current generator Gen and the interrupter I. The ringer at substation A will now be operated at intervals in the usual manner to signal the called subscriber.

The required connection has now been established and the desired party is being signalled automatically in the usual way. Before proceeding with the operations which take place when the called subscriber answers it will be well to consider the release of the register switches which takes lace as soon as the connection is establishe by the insertion of the plug in the jack of the called line. When the -plug of cord lcircuit O is inserted in jack J a branch path may -be traced from the sleeve of the plug by way offconductor 232 and the winding o frelay 2 00 tol battery. Relay 200 is therefore energized in parallel with relay 208 when the plug is inserted in the jack and opens at its armature 213 the inductive path which extends from trunk conductor 130 by'way of the condenser to conductor 243, opens the circuitof lamp L at armature 212, and at its armature 215 opens the holding circuits of relays 250 and 300 .of the individual line switch C and the register switch R1 respectively. Upon deenergizing, rela 250 wipers of the line switc C' and the switch is thus restored to normal condition. When relay 300 deenergizes ground G1 is connected to conductor 330 with the result that the previously prepared circuits for the release magnets 305, 363, 383, and 403 of register switches R1, R', R. and '.R, respectively, are completed and the said switches are restored to normal position. When the switches reach normal position relays 301, 360, 380, and 402 are deenergized and the release magnet circuits of the several switches are broken. Relay 301 also disconnects ground from the test contact 266 and its multiples thereby renderin the No. 1 register set accessible to other cal s. When the register switches are released as above explained, ground is removed from conductor 328 and relay 500 is deenergized. This relay disconnects ground from the common conductor 513 and opens the circuit of relay 501. Relay 501 then falls back, closes the loop at armature 508 and at amature 507 disconnects ground from the circuit including relay 502 and conductor 327. By the latter operation relay 502 and the relays 317, 362, 382, and 400 1n the four register switches are deenergized, whereupon the lighted lamps in the indicating device will be extinguished.

Returning now` to the established connection, while the calling subscriber is bein signalled automatically as before explained the' calling subscriber in the automatic exchange is given the well known ringin current induction by means of the circuit through ythe high' resistance 233 which bridges the open contact in the upper strand of the cord circuit at armature 223 of the ringing relay 205. This resistance ermits sufficient ringing current to leak bac in the direction of the calling subscriber to give an audible signal each time ringing current is applied to the called line, and he is thereby advised that the ringing operation is proceeding. This so calle ringing current induction is standard practice in automatic systems and by providing for the same thin in the B operators circuit I secure uniform operating conditions. To proceed, the

ring cutoff relay 206 is included in the ringing circuit, but does ,not energize as long as the receiver at substation A remains on the hook. When the called subscriber at disconnects the lli f substation A removes his receiver responits armature 226 short circuits relay 205 and 4locks itself in the circuit over the sleeve of the cord. In other words, relay 207 1s substituted for relay 205, and it may be mentioned that relay 207 is of the same re sistance as relay 205 and the supervisory lamp LB therefore remains shunted out.

When relay 205 deenergizes the ringing circuit is broken and the upper and lower talking strands of the cord circult are connected, whereupon the talking circuit willl have been completely established. p

The calling subscriber is supplied with talking battery through the windings of line relay 101 of the re eater E and the called subscriber is supp ied with talking battery -through the right hand windings of the repeating coil at the cord `circuit O'. Relay 209 is included in the latter circuit and is operated by current flow through the transmitter at substation A to attract its armature 222 and close the circuit of the reversing relay 204. By the operation of the reversing relay 204 the trunk conductors 130 and 131 are reversed as regards their connections with the windings of the line relay 203 and the direction of current flow over the conductors of the trunk line is therefore reversed. The direction of current flow through the upper winding of the electro-polarized relay 105 at the repeater E is therefore reversed and this relay is now operated. At armatures 118 and 120 relay 105 closes the bridge over a path which is independent of the contacts controlled by relays 103 and 101 so that the elements no-rmally in the bridge cannot be cut out or the bridge opened by accidental operation of the dial at substation A. In additio-n, at armature 119, relay 105 closes` a circuit for the reversing relay 100 in the repeater, which operates in the same w'ay as was described in the case of the reversing relay 204 to reverse the direction of current flow in the line of substation A. This operation may be used for operating a meter or supervisory apparatus and is provided for according to standard practice, although it is of no utility in the particular circuit shown. By operating its armature 107, relay 100 introduces the left hand winding of the impedance coil 106 in the bridge across trunk conductors 130 and 131 in series with the right hand winding of this coil, thereby increasing the impedance of the bridge and increasing the eificiency of the talking circuit. p

The required @Onneeton having been established, the subscribers may now converse as desired. When the conversation is iinished both subscribers will hang up their receivers. When the receiver is replaced at substation A the circuit of the line relay 101 of the repeater Ev is broken and relays 101 and 102 are therefore deenergized- 'i 4The latter relay breaks the'holding circuit extending back to the line switch C and the selector D by retracting its armature 112,'v and as a result relays 13 and 55 are deenergized. Relay 13 in the line switch C disconnects the `\wipers of the line switch which'fis thereby restored to normal condition ready for use in another call. Relay 55 closes the circuit of the release magnet 57 at its lower armature and the operation ofthe said magnet restores the selector D to normal position 1n the usual manner, the circuit of the release magnet being broken by the off normal springs when the switch is completely restored. When the relay 102 of the repeater deenergizes it also opens at its armature 113 the bridge across the trunk cond uctors 130 and 131, and thereby causes the line relay 203 at the cord circuit O to deenerglze, resulting in the deenergization of slow acting relays 201 and 202 also. Relay 202 by retracting its armature 220 opens the shunt path around the supervisory lamp L8 which extends through the relay 207 to battery, and thereby causes the lamp L8 to be lighted to give the operator a dis- .connect signal. Relay 201, upon deenergizing, permits the contact springs controlled by its armature 216 to close thereby connecting the lower winding of the line relay 203 by way of resistance 234 to battery instead of ground to which it was formerly connected. By this operation a circuit is established for relay 104 at the repeater which extends as follows: grounded armature 110 of line relay 101, resting contact of the said armature, armature 115 and its resting contact, winding of relay 104, conductor. 131, lower left hand winding of the repeating coil, contact springs controlled by the lower armature of reversing relay 204 (this relay being now deenergized), lower winding of line relay 203, normally closed contact springs controlled by armature 216, armature 214 and its working contact, and the resistance 234 to battery. The relay 104 at the repeater E is energized by current flow over the above circuit and upon attracting its armature 117 again connects ground to the conductor 77. By this foperation the test contact 74 and its multiples in the banks of the other office selectors are again grounded and the trunk line is made busy.

The automatic switches have now been released, a disconnect signal has been given to the operator, and the trunk line in use has been made busy pending the pulling down 0f the Connection at the .B board. When the operator observes the lighted supervisory lam L she will remove the lug of cord circuit O from the jack and reliays 230 and 208 will be deenergized, and the lamp La will be extinguished. Also the relay 200 will be deenergized and ground will again be connected to the lower winding of the line relay 203, as is the normal condition. Relay 104 at the repeater E is therefore deenergized and ground is disconnected from conductor 77 with the result that the trunk line is restored to idle condition. The apparatus has now all been completely returned to normal in readiness for use in other connections.

It will be convenient now to revert to the consecution controller N and consider its operation a little more in detail. It will be understood from what has been said already that when a call is received and the registration thereof is completed the relay such as relay 500, 520, etc., in the consecution controller which corresponds to the register set in use will be energized and the associated pilot lamp will be lighted. Thus when a call is registered on register set No. 1, pilot lamp L is lighted and relay 500 is energized, when a call is registered on register set No. 2 pilot lamp L2 is lighted and relay 520 is energized, and so on. N ow when a call is received on any register set, if the consecution controller is idle, that is, if there is no call switched on to the indicating lamps, the registered call will be switched on at once, as in the case previously described. But if a second call is received and registered while a prior call which has been switched oii to the indicating lamps is waiting undisposed of, the call last registered will have to wait. This does not occur very often for the operator can plug up connections very rapidly; nevertheless it sometimes happens that two or three calls or perhaps even more are received and registered nearly at the saine time and registered calls may thus accumulate faster than the operator can handle them. This condition is only temporary of course and the operator isgenerally able to catch up in a short time. lhe accumulated calls are stored on the register sets, which are provided to the extent of four or more, as shown, to take care of these emergencies, and are switched on to the indicating lamps as fast as the operator can plug up the connections.

The consecution controller takes care of this, as will now be explained. Suppose that in the case previously described, in which case a call was registered on the No. 1 register set, calls are received and registered on the No. 2 and No. 4 register setsbefore the call on the No. 1 set is taken care of by the operator. Lamps L2 and L* will accordingly be lighted and relays 520 and 560 will be energized by ground on conductors 538 and 578, respectively, but neither rela 521 or relay 561 will pull up because, a though the circuits of these relays are closed, the common conductor 513 is grounded at armature 506 of rela 501 and both relays 521 and 561 will be s ort-circuited. It follows therefore that the calls on register sets Nos. 2 and 4 will be held waiting pending the disposition of the call on the No. 1 set. VVheu the operator completes this connection the register switches of the No. 1 set are released, pilot lampy L is extinguished, and relay 500 is deenergized. When relay 500 falls back it removes found from conductor 513, whereupon rerlays 521 and 561, being no longer short circuited, at once start to pull up. But only relay 521 is actually operated. The loop circuit to which both relays are connected is now grounded at armature 509 of slow acting relay 502 and when relay 521 pulls up it breaks the loop at armature 528 thus disconnecting the loop ground from the .winding of relay 561 but not from its own windin Relay 561 therefore at once falls back w ile relay 521 pulls clear up and again grounds the common conductor 513. Relay 521 also grounds conductor 537 by way of the winding of slow acting relay 522 and relay 317 and associated relays in the other register switches of the No. 2 register set are energized to light the roper lamps on the indicating device. Tius the call is switched over. Relay 522 is energized in series with the relays in the several register switches and at its armature 529 rounds the loop circuit in the direction cfg the relays associated with the No. 3 register set. Relay 522 pulls up before relay 502 falls back, and since the loop is now closed at armature 508 of relay 501, relay 521 will be held up over the loop circuit. It is noted also that relay 522 connects ground to relay 511 at armature 530 so, that this relay is maintained energized.

Suppose now that another call is received and registered on the No. 1 set before the `call on the No. 2 set is disposed of: Pilot lamp L is again lighted and relay 500 is energized, but relay 501 is not energized due to the ground on conductor 513. lVhen the operator finishes with the 'call on the No. 2 set, the register swtiches are released, pilot lamp L2 is extinguished, and relay 520 is deeiiergized. Ground is thus removed from conductor 513 and relays 561 and 501 at once start to pull up. Relay 561, however, breaks tlie circuit of relay 501 at armature 568 and relay 501 immediately falls back again. Relay 561 is completely energized, grounds conductor 513 again at armature 566, and at armature 567 completes a circuit over conductor 57 7 for energizing the relays of the fourth register set which light the .lamps in the indicating device.

Relay 562 is --energized in series with these relays, establishes a holding or locking circuit for relay 561 by grounding the loop at armature 569, and -at armature 570 closes another. circuit for relay 511. When the call on register set No. 4 is disposed of the call on register set No. 1 will be switched over` even though in the meantime a. call has been registered on the No. 2 or the No. 3 set, for the relays which are associated with the No. 1 set are next in order in the loop circuit after the relays associated with the No. 4 set. Thus it will be seen that the consecution contro-ller provides for testing the register sets in regular order and no register set is given preference over any other. It will be understood of course that although the consecution con-troller is herein shown wired and equipped for four register sets, a lgreater number may be used if desired, other relay groups being added and wired the same as those shown.

While as stated the consecution controller heretofore described provides for testingthe register sets in regular order, it does not absolutely insure that the registered calls will be switched over in the precise order in which they are registered. This is because the rotary line switches such as the line.`

switch C have no normal position and when a call is received it may be registered on any idle register set, the set selected being a matter of chance entirely. There is a tendency of course during busy periods for the register sets to be Selected in order, more or less, because the line switches when selecting move-ment thereof is required move forward, but this is not to be relied on, and it may happen that consecutive calls are registered in the order four, three, two, one, on the register sets. Now since the consecution controller tests the register sets in the order one,

t two, three, four, it will be evident that the three calls last registered will be switched over in the inverse order of their registration. The call on the third register set which was the second call to be registered will be the last to be' switched over. This is the worst condition that can happen and will occur very seldom, although it may hap en quite frequently that a call is delayed'w ile a single later registered call is switched on ahead of it.

The objection thus introduced is not very serious and can usually be ignored. But there is no doubt that somewhat better service can be given if the consecution controller is arranged So that it will switch over calls in the exact order in which they are registered; and it may sometimes be considered worth while to do this, even though more complicated apparatus is required. In Fig. 5 I have shown a consecution controller which accomplishes the desired object and this apparatus will now be explained. The

consecution controller in Fig. 5 is intended to be 4substituted for the consecution controller N, F ig.2, when desired. Conductors 328 and 327, ilot lamp L', and relay 500, all shown at t e upper left hand corner of the sheet, Fig. 5, are associated with the first register set and are the same as the same numbered apparatus in Fig. 2, although relay 500` has a somewhat different function. The line switch C2 is a rotary line switch of the same general .construction as the line switch C, Fig. 1, but has somewhat different circuits and is provided with an extra wiper and bank of contacts for restoring it to a normal position. Line switch C2, is individual to the first register set. There is a similar line switch for each of the other register' sets although such switches are not shown, and the banks are connected in multiple. The rest 0f the apparatus shown in Fig'. 5 is common to the position and comprises relays 600 to 603, inclusive, one for each register set; relays 604 and 605, which are paired with relays 600 and 601, respectively; and the consecution control switch C3. The latter is a rotary line switch of the same general type as the others used herein and does not restore to normal. As Stated, there are as many of the relays 600, 601, etc., as there are register sets but these relays are not individual to particular register sets, but on the contrary any relay may be reached from any register set. The relay connections are multipled in the banks of the line switches such as line switch C2 in the following manner: the line switches have twenty live contacts in their banks and these contacts are divided into five groups of live contacts each, y0f which one group is shown in the drawing. The first group is wired as shown and the other groups are connected in multiple with the first, the result being the same as though there were only five contacts in the banks. The first contact of each group is a normal position contact while the other four correspond to the four relays 600, 601, etc.

With this explanation the operation may be described as follows: Assuming that a call is registered on the No. 1 register set, when the registration is completed the conductor 328 will be grounded, pilot lamp L is lighted, and relay 500 is energized. Relay 500 thereupon closes a circuit for the line relay 610 of line switch C2. Upon energizing, relay 610 disconnects wiper 613 at armature 617, closes a circuit through the switching relay 611 in series with the stepping magnet 612 at its armature 618, and at its armature 619 connects the test wiper 615 to this circuit at a point between the said switching relay and stepping magnet. Since theunormal position contact on which wiper 615 is now resting is grounded, the switching relay will be short circuited and the stepping magnet will be operated to advance the wipers 613-616, inclusive, one step. If we assume now that the second set of contacts is idle, test wiper 615 will no longer find a ground potential and the rotation will cease. The switching relay 611, being no longer short circuited, is energized at once and at its armature 621 'connects the test wiper615 to ground, thus rendering the selected Contact set busy. At the same time, relay 611 closes a circuit for relay 600 at armature 622, the said circuit being traceable by way of wiper 614, conductor 624, winding of relay 600, common conductor 628, and the winding of the line relay 640 of the consecution control 604. Upon energizing, relay 604 grounds the second contact in the bank of line switch C2 and associated line switches, and also locks itself to common conductor 629, which has been grounded by the energization of the line relay 640 of the switch C3.- 'Ihe line relay 640, which is energized 'in series with relay 60() as explained, in addition to grounding conductor 629, connects up the test wiper 644 by means of its armature 646 and if the Contact upon which the said test wiper is resting is grounded the stepping magnet 642 will operate in series with slow acting relay 641. It may be assumed, however, that the wipers of the consecution control switch C3 are resting on the first contact set as shown in the drawing and under these circumstances, since ground has been removed from the contact with which wiper 644 is in engagement by the energization of relay 600, no rotation of the switch will take place. A circuit for grounding conductor 327 has now been established as follows: from the grounded armature 645 of relay 640 by way of the working contact of the said armature, armature 648 and its resting contact, wiper 643 and contact engaged thereby, conductor 649, bank contact engaged by wiper 616 of line switch C2, wiper 616, and armature 620 and its working contact to conductor 327. By the grounding of conductor 327 relays 317, 362, 382, and 400 are `energized and the call is thus switched on to the indicating lamps.

1t will be assumed now that another call is registered on another one of the register sets before the call on the first set is taken care of by the operator. When tlie'secon'd call is registered the line switch assciated with the register set in use is opera and remembering now that all the line s l tches stand normally on the first contact setn a group, as vshown in the ease of' line switch C2, and that the Second contact set is busy because seized by line switch l2, it will be clear that the line switch now heilig operated Will connect with the third set of contacts in its bank. By this operation relay 601 is energized in an obvious manner, and this relay disconnects ground from the second test contact in the bank of the consecution control switch. A circuit is also closed for relay 605 which energizcs, locks itself to grounded conductor 629, and grounds the third test contacts in the banks of the line switches.

Suppose that, now the operator completes the connection registered on the No. 1 register Set. The register switches are thereupon released, pilot lamp L is extinguished and relay 500 is deenergized to break thc circuit of line relay 610 of line switch (l2. The line relay 610 then falls back. breaks the circuit of the switching relay 611 and closes a circuit for the stepping magnet 612 by means of armature 617. Under control of wiper 613 the wipers of line switch C2 are new advanced step by step by the magnet 612 until they arrive at one of the normal positions, when wiper 613 will no longer find ground and the rotation will cease. lVhen the switching relay 611 dcenergizes ground is removed from wiper 614 and the circuit of relay 600 is broken. This relay thereupon falls back and grounds the first test contact in the bank of the consecution control switch C, The line relay 640 is in operated position at this time andi since test wiper 644 is standing on thc first test contact the instant relay 600 falls back the stepping magnet 642 and slow acl,- ing relay 641 will be energized in series. The former interrupts the circuit at each energization and it follows that the switch will advance its wipers until the test wiper 644 finds an ungrounded test contact. Only one step will be taken in the present case` for relay 601 has cleared the second test contact of ground and the switch will stop with wipers 643 and 644 resting on the second contacts of their respective banks. An inst-ant later relay 641 1s dcencrgizcd and groundl'is extended by way of wiper 643 and conductor 650 to the third contact in the lower, bank of all the line switches, where it is picked up by the lower wiper of the line switch associated with the register set in use. If the second register set, for example, is being used, this wiper will connect With-conductor 537 and the relays in the register Vswitches which light the indicating lamps will be energized. Thus the second call is switched over.

It is to be. noted that when line switch C2 is released relay 604 remains locked up, provided'there is a call waiting, although relay 600 is deenergized. Suppose now that another call is registered. This may be on the first register set again as this set is l(lll idle.

When line switch C2 is operated on the completion of 4the registration it will not now connect with relay 600, as before, because the second set of contacts are held busy by relay 604, but thel, switch will advance its wipers to the fourth set of contacts and wiper 614 will connect with relay 602. Rela 602 is accordingly energized with results which will readily be understood. Now when the second registered call is completedv by the operator the register set and line switch associated therewith are restored, relay 601 is deenergized, and ground is placed on the second test contact in the bank of the consecution control switch CS. This switch therefore will advance its wipers another step and will stop with test wiper 644 in engagement 4with the third test contact, ground having been removed from this contact by relay 602. Ground is then connected to wiper 643 and the third registered callr is switched over as previously explained.

If a fourth call should be registered before the operator has handled the third call the line switch of the register set in use will of course connectI with relay 603 because the second and third sets of contacts are held busy by relays 604 and 605, respectively, and the fourth set of contacts is held busy by reason of the fact that an operated line switch is standing on such contact set. 'When relay 603 is energized the common conductor 629 is disconnected and relays 604 and 605 are unlocked and the first and second sets of contacts are again made available for use. It will be observed that in case the operator gets all calls cleaned up at any time before the fourth position on the consecution control switch is taken by a call, there will be no calls waiting, and the line relay 640 will fall back. This removes ground from common conductor 629, any relays such as relay 604 which have been locked up will be unlocked, and the operations start afresh with the next registered call. If desired a larger number of registers may be used and the relays 600, 601, etc., are then correspondingly increased in number. Relays such. as relays 604 and 605 are of course added also, there being always two less relays of this type than there are of the other, and the bank wiring is modified to take care of the added number offrelays. This, however, will be readily understood and will need no further explanation.

Before concluding, a brief explanation will be given of the means employed to give the calling subscriber a busy signal in the case where a call is receivedA at the operators position when all the register sets are busy. The common conductor 450 is normally grounded .at each of the register sets, the ground vconnection bein-g shown in the case of the No. 1 register set at the resting coiilamp L9 to indicate the condition of all register sets busy, and at the same time switches the conductor 451 from battery into connection with the winding of relay 454. Conductor 451 is a common conductor which supplies battery to the line relays, such as line relay 351, of all the rotary line switches, such as the rotary line switch C', whcli are associated with this particular operators position. Suppose now that a call is received over the trunk line terminating in the cord circuit O. When relay 202 at the cord circuit is energized and closes the circuit of line relay 251, the said line relay is not now operated, due to the fact that the circuit now includes the winding of the high resistance relay 454. Relay 454 is energized, however, and connects the busy signalling machine Q, with the common conductor 452 which extends to all tlie rotary line switches, as shown in the case of the line switch C. The circuit from the busy signalling machine may now be traced b way of the common conductor 452, resting contact of armature 253 and the said armature, conductor 243, armature 217 and its working contact, armature 213 and its resting Contact, and the condenser to the trunk conductor 130. It follows that the calling subscriber will be given a busy signal, which indicates to him that for the time being the desired connection cannot be obtained and he will replace his receiver.

Having described my invention, what I consider to be new and desired to have protected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a telephone system, a plurality of register sets at the exchange accessible to calling automatic subscribers for registering called telephone numbers, an indicating device common to said register sets for indicating registered numbers to an operator, and a consecution controller comprising an automatic step by step switch for switching registered calls on to said indicating device one at a time.

2. In a telephone system, a plurality of register sets at the exchange accessible to calling automatic subscribers for registering called telephone numbers, an indicating device common to said register sets .for indicating registered numbers to an operaregister sets at the exchange accessible to callingI automatic subscribers for registering called telephone numbers, an indicating device common to said register sets for 1ndieating registered numbers to an operator, a consccution controller for switching registered calls on to said indicating device one at a time, and an automatic switch individual to each register set for connecting the same with said controller.

4. ln a telephone system, a plurality of register sets at the exchange accessible to calling automatic subscribers for registering called telephone numbers, an indicating device common to said register sets for indicating registered numbers to an operator, a consecution controller for switching registered calls on to said indicating device one at a time, an automatic switch individual to each of said register sets, and circult connections whereby said controller is rendered accessible to said switches over a plurality of different paths.

5. In a telephone system, a plurality of register sets at the exchange accessible to calling automatic subscribers for registering called telephone numbers, an indicating device common to said register sets for indicating registered numbers to an operator, a consecution controller for switching registered calls on to said indieating device one at a time, a selecting switch individual to each of said register sets, a pluralityof circuits extending to said controller and accessible to said switches. and means for rendering said circuits selectable in a definite and predetermined order.r

6. In a telephone system, a plurality of register sets at the exchange acceible to calling automatic subscribers for registering called telephone numbers, an indicating device common to said register sets for indicating registered numbers to an operator, a consecution controller for switch-ing registered calls en to said indicating device one at a time, and cooperating means whereby such calls are always switched on in the exact order in which they are registered.

7. The combination, with a plurality of register sets selectable at random, of an indicating device common to said sets, and a consecution controller for associating occupied register sets with said device one at a time, said controller including means for sorting the register sets after they are occupied and for associating the occupied sets with said device in the exact order 1n which the calls are registered thereon,

In witness whereof, I hereunto subscribe my name this 28th day of November, A. D.

RODNEY G. RICHARDSON:

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