US1855724A - Multioffice telephone system - Google Patents

Description

April 26, 1932. 1 NELSON 1,855,724-

MULTIOFFIGE TELEPHONE SYSTEM Original Filed July 6, 1922 7 Sheets-Sheet l InUEntDP P'Tarim L. Nelson April 26, 1932. M. L. NELSON 1,855,724

MULTIOFFICE TELEPHONE SYSTEM Original Filed July 6, 1922 7 Sheets-Sheet 2 .J. j r

April 26, 1932. NELSON 1,855,724

MULTIOFFIGE TELEPHONE SYSTEM Original Filed July 6, 1922 7 Sheets-Sheet 5 {\J k w Elnw: Q6 RR i Imus-aim" April 1932- M. NELSON 1,855,724

MULTIOFFICE TELEPHONE SYSTEM Original Filed July 6, 1922 7 Sheets-Sheet 4 Inu"e"n1'u'r" Mar 111 L. Nels an April 26, 1932. M. L. NELSON MULTIOFFICE TELEPHONE SYSTEM 7 Sheets-Sheet 5 Original Filed July 6, 1922 RN MN Mm L. Nels an m April 26, 1932. M. NELSON 1,855,724

MULTIOFFICE TELEPHONE SYSTEM v Original Filed July 6, 1922 7 Sheets-Sheet 6 IHUETL U1" Mm L. Nels on April 26, 1932. M. L. NELSON MULTIOFFICE TELEPHONE SYSTEM Original Filed July 6, 1 922 7 Sheets-Sheet 7 --=Iu War" 111 L.Ne1s an .ori mai application filed m Patented Apr. 26, 1932 NITED .ST'ATES PATENT OFFICE.

maria 1;. NELSON, or 'PARK RIDGE, ILLINOIS, Assmn'on, BY ERNIE-ASSIGNMENTS,

1 RATION OF DELAWARE The present invention relates 'in general to .mul'ti-oflice telephone systems, but more in are called, in combination with translating and sending mechanism for routing the calls to their destinations, and the main object is to produce a new and improved director,

which may be considered asan improvement on the director shown and described in the British Patent 194,580. Although, as stated, the invention is applicable generally to multioffice systems of the type mentioned, as to a large number of features it is especially adapted for use in a multi-office system comprising both automatic and manual oflices.

It is common practice, whenconverting a multi-ofiice manual system to automatic I operation, to replace the manual equipment by automatic equipment one office at a time, the transition period often extending overa period of several years. Accordingly, during the time whensome of the offices are I being operated automatically and others manually, arrangements must be made whereby theentire system may operate as a unit; The director shown in the present application is designed for use in an automatic office of a mixed oil'ice multi-ofiice system comprising two or more automatic ofiices, an individual line manual office, and a party line manual office. Calls are trunked from one automatic oflice to another according to standard automatic practice, while calls from an automatic office to the manual oifices are preferably handled by calls indicating apparatus adapted to display the called numbers to operators according to the general principles set forth in the U. S. Patent 1,475.590, granted Nov. 27, 1923 to Martin and Willis. i In a complex system of the foregoing character it will generally happen that the telephone numbers are not uniform throughout all the oflices as to the number of digits, and

a special object of the invention, therefore, is

the proyision ofa director which is adapted to set up connections to various oflices of the type mentioned irrespective of the number 6, 1922, Serial no. 578,175. Dividedahd this 1927. Serial No. 203,086.

, TO ASSOCIATED ELECTRIC LABORATORIES, INC., 01" CHICAGO, ILLINOIS, A CORPO- uumxorrroa TELEPHONE sYs rnm appllcation, filed July 8,

of digits in the telephone numbers. While of, a system will be assumed by wayof ex- ;various kinds of numbers may be taken care ample, in which the numbering scheme for each of the automatic ofiices is laid out according to the jack per station plan, accordmg 7 to which plan the subscribers number comprises only four digits, whether the subscriber is a party line subscriber or an indiv dual llne subscriber; in which the party line manual ofiice numbering scheme is such that each subscribers number comprises four digits for determining the called line andla fifth digit for 'determining the de{ sired subscriber on the called line; and in' which the individual line manual ofiices are equipped with the same kind of call indi cators at the incoming call indicator B positions as are used in the party line manual offices, which call indicators require five digits .to be called in the subscribers number before the number is displayed to the operator. In the individual line manual ofiices, the fifth digit lamps are removed from the call indicators and the'fifth digit dialled has no function other than to switch the indicator into position to display the four digits of. the subscribers number to the operator. The above arrangement allows the standard five digit call indicators to be in each oflice ofthe system, which from a manufacturlng standpoint alone, is a considerable ad vantage;

In the director, suitable circuit arrangements are made such that, when the call is gomg to an automatic oflice, the four digits cator through, the digit 1 is added by the director, whereupon the director is cut off 1 as before. v

Another object of the invention is to pro-.

vide, means whereby the director is automatically cut off and the connection switched through to the first selector, if no dialling occurs during a predetermined interval, this being done under the assumption that, since no digits are d1alled, the su scribers l1ne 1s accidently short circuited or grounded and, consequently, that the seizure of the director was not due to the subscriber initiatmg a call; and whereby if no dialling occurs during a predetermined interval after the subscriber has dialled one or more dlgits, the call is trunked through automatically by the director to the monitoring operator.

A further object is the production of c1rcuit arrangements, whereby the oflice register of the director is automatically rotated one step upon the calling of the digit 0, whichis the digit dialled when the long distance operator is desired, so as to place the director in condition to send out the code necessary to trunk the call to the long distance operator.

The features pointed out above are claimed in my application, Serial No. 573,175,

filed July 6, 1922, of which the present appli cation is a division. The features claimed in this divisional application include the provision of new and improved c rcuit arrangements for use 1n connect on with a director system whereby service is given to automatic paystation lines.

Another object is the provision of circuit arrangements, whereby a paystation subscriber may call the long distanceoperator without depositing a coin, but cannot obtain connection with a subscribers line without first depositing acoin, the circuit ar-.

rangements being such that the call is trunked through immediately to the monitoring operator,-in case the first digit dialled by a paystation subscriber is other than 0, unless he has deposited a coin.

A still further feature is the provision of circuit arrangements, whereb the same director may be used by subscri ers on paystation lines and by subscribers on other lines, and whereby the director is rendered fully operative automatically independent of any act performed by a subscriber when he is calling from any line other than a'paystation line.

The other features relate principally to circuit improvements and will become apparent upon a further perusal of the specification.

Referring to the drawings, Fig. 1 shows a paystation line extending from the paystation telephone A to the individual line switch C in the exchange; Fig. 2 shows a paystation repeater R accessible to the line of substation A, and a secondary switch SS which has access to a plurality of directors; Fig. 3 shows an SS, individual to the ordinary station A. switch C, a repeater scrlbers lme switch line, individual line B accessible to the sub- C', the secondary switch repeater R, and havgether with the mg access to the same directors as the secondary switch SS, Fig. 2, and a first selector D' associated with the repeater R; Figs. 17, inclusive, show the improved director; and Fig. 8' is a layout showing how Figs. 1 to, 7, inclusive, join together The automatic substation A, Fig. 1 has the usual talking, signalling, and switch control instrumentalities, and being a paystation telephone, has coin controlling and coin controlled mechanism. The substation A, Fig. 3, is similar to the substation A, except that the circuit is somewhat simpler and no coin mechanism is provided.

The line switch C, Fig. 1, in which the line of substation A terminates is of the wellknown rotary type in which the wipers have no normal position and move in a forward direction only. The line' switch C, Fig. 3, is identical with the line. switch C.

The repeater R, Fig. 3. which is inserted in the trunk ahead of the first selector D, is proyided for the purpose of repeating the number dialled by the calling subscriber into thd director and for r eating from the dire or into the automatic switches. The repeater R, Fig. 2. is similar to the repeater R,'. with the exception that the repeater R. being a naystation repeater. has arrangements for deferring the grounding of a certain conductor in the director trunk until the calling subscriber has deposited a suitable coin. The repeater R has also the usual arrangements for collecting or refunding the coin when the calling subscriber hangs up.

The secondary switch SS. Fig. 2. is mechanically identical with the line switch C or the line switch C, and has its circuits suitablv'arrangedfor selecting an idle director when the trunk with which it is associated is seized. The secondary switch SS is mechanically identical with the secondary switch SS and has practicallv the same circuit. Such differences as exist will becomeapparent when the lhereinafter given detailed description is rear.

The secondary switches SS .nd SS. to-

other secondary switches in the same secondary group. have access to a pluralitv of directors such as the one shown in Figs. 4-7. inclusive. by way of four conductor trunks such as the one comprising conductors 101-104. inclusive. The director a ccessible by way of this latter trunk comprises. in addit on to various controlling relays. the master digit controller MDC. Fig. 4: the ofliceregister ()Rand the intermediate distributing frame IDF. Fig. 5: 5 sequence switch S, Fig. 6: the digit registers DR-DR. inclusive. Fig. 7 and the sender which comprises certain relays shown in F ig. 6 and the counting relays shown in the lower part of Fig. 7.

The master digit controller MDC. Fig. 4. is mechanically a so-called mindr switch and has a pair of wipers 253 and 254 which are the circuit of release magnet 250 when the wipers reach normalposition. The digit registers DR-DR, inclusive, are each mechanically identical withthe master digit controller MD C, with theexception that the wipers of the digitregisters are normally out of engagement with their associated bank contacts, whereas the wipers of the master-digit controller are normally in engagement with the first associated bank contacts. Afurther difference is that each of the digit registers is provided withonly one wiper and each has an extrapair of off normal contacts, as shown.

The ofiice register OR,Fig. 5, is "a Strowger switch of the vertical and rotary type, having 100 sets of contacts arranged in tenhorizontal rows or levels. This switch is directively controlled in its vertical and rotary movements by impulses delivered to its vertical and rotary magnets by way of the master d glt controller MDO. This off ce register is provided with four wipers 260-263, inclusive,

which have access to each of the 100 sets of bank contacts, of which four sets are shown. The vertical, rotary, and release magnets of the switch are indicated by the reference characters 229-231, inclusive, respectively. This switch is provided with an off normal combination comprising spring 232 and its upper contact and also the normally open contacts controlled by spring 232. The normally open contacts controlled by spring 232 are adj nsted to close when the switch wipers are raised opposite the first level of bank contacts. Spring'232, however, does not break away from its associated lower contact and come into engagement with its upper contact until the wipers of the switch are raised opposite the second level of bank contacts; This adjustment enables circuit arrangements to be made, whereby the switch is released each time it comes to rest opposite the first level of bank contacts, which level of contacts is left dead and does not correspond to any ofiice numbers. Theswitch OR is provided also with the tenth level spring combination comsets not being used in this particular case.

The ten impulse conductors comprising conductors 291-300, inclusive, together with the special conductors 301-306, inclusive, "are terminated on the right-hand side of the IDF, and each maybe multipled to as many contacts as desired in order to facilitate the runv f the special conductors 301-303, inclusive, conductor 301 is the switch conductor andis used to switch the director through when the nnmber'called is not a subscribers number, such as, for example, when the long distance operator is being called by the director, by dialling 46.

Conductor 302 is the automatic oflice discriminating conductor and accordingly, a jumper is run to it from the fourth bank contact of each set of contacts that represents an automatic oflice, so as to place the director in condition to send properly and, switch through at the right time, the director being et so as toxadd the digit .1 to the individual line manual numbers so as to switch the call indicators in the individual line manual ofiices after the four digitsof the num# her are dialled.

The fourth contact in each set of contacts that represent a manual party line number is jumpered to conductor 303, so as to place the director in condition [to receive and send out the digit corresponding to the desired station on the called party line.

- Conductors 304-306, inclusive, are the usual skip conductors and are provided for the purpose of causing the sequence switch S, Fig. 6,

to advance automatically past the second,

. armature.

In the drawings the slow acting relays are denoted by shading the lower portion of their cores, or by making the upper portion of their cores solid black, depending upon whether the relay is merely slow to release or is also slow to operate. The shaded portion on the lower end of the core of a relay indicates that-that re av is slow to release after its circuit is opened, but is not appreciably slow to operate upon a closure of its circuit. On the other. hand, a solid black portion on the upper end of the core of a relay indicates that thatrelay is slisrhtlyslow to pull up after its circuit is closed, in addition tobeingslow to' release after its circuit is opened.

7 tion having been set forth in eneral in the foregoing, the operation of t e e 'uipment shown will now be described more 1n detail.

For this purpose, it will be assumed first that the subscriber at substation A desires -to call a subscriber whose number is 5678, and whose line terminates in the office, the first two let ters of which are numerically equivalent to 91, it being understood, of course, that the letters of the alphabet appear on the subscribers calling-devices and that the subscribers dial the first twd -letters of the ofiice name.

lVhen the receiver is removed at substation A, a circuit is closed over the associated lineconductors for relay 111 of the line switch G. Relay 111, upon energizing, closes a circuit for switching relay 110 and steppin magnet 112 in series at armature 117, anc at armature 116 connects test wiper 119 to the junction of relay 110 and magnet 112. In case the trunk upon which the wipers of the line switch C are standing is idle, the latter operation has no effect and switching relay 110 energizes immediately. However, assuming the trunk upon which the wipers are standing to be busy, switching relay 110, being short circuited by the ground potential which is present on the test contact thereof, does not energize, and the switch wipers 118-120, inclusive, are automatically advanced step by step in search of an idle trunk by the buzzer like action of step ing magnet 112. lVhen an idle trunk is reac ed, WlllCh trunk it will be assumed is the comprising conductors 121-123, inclusive, switching relay 110, being no longer short circuited, energizes in series with stepping magnet 112, stepping magnet 112 not energizing at this time on account of the high resistance of switchin relay 110. Upon energizing, switching re ay 110 opens the test circuit and prepares the holding circuit at armature 114, thereby making the seized trunk busy immediately, and at armatures 113 and 115 disconnectsthe conductors ofthe calling line from the winding of line relay 111 and ground and extends them by way of wipers 118 and 120, trunk conductors 121 and 123, and the resting contacts of armatures 131 and 134 and said armatures to the windings of line relay 125 of the re eater R. Line relay 125, upon energizing, c oses a circuit for line relay 137 of the secondary switch SS at armature 128. Relay 137, upon energizing, disconnects release trunk conductor 122 of the repeater R from release trunk conductor 161 of the selector D, and places ground on the former at armature 141,'thereby establishing the usual holdin'gcircuit for the line switch C before line relay 111 has had time to deenergize; closes a circuit for switching relay 138 and stepping magnet 147 in series at armature 140; and at armature 139 connects test wiper 149 to the junction of switching reone the test contact'thereof, and the wipers 148-151, inclusive, are advanced step by step in search of an idle trunk by the buzzer like action of stepping magnet 147 lVhen an idle trunk is reached, which trunk it will be assumed is the one comprising conductors 101-104, inclusive, test wiper 149 encounters an ungrounded test contact and switching relay 138, being no longer short circuited,

energizes in series with stepping magnet 147. Stepping magnet 147, however, does not energlze at this time on account of the high resistance of switching relay 138. Upon energizing, switching relay 138 opens the test circuit and places ground on test wiper 149 at armature 144, and at armatures 143, 145, and 146 connects up wipers 148, 150, and 151. respectively. ground on test wiper 149, conductor 102 is grounded, whereu on relay 204, Fi 4 energizes; connects t e timed impulse lbad 209 to the lower winding of relay 201 at armature 217; disconnects ground from the release lead 242 at armature 216; and at arma-. ture 215 prepares a locking circuit for relay 201. As a result of the connecting up of wiper 151 of the secondary switch SS, ground is placed on lead 104, thereby ground ing the last eight contacts in the lower bank of the master digit control switch MDC, Fig. 4, and closing a. circuit for relay 208. Relay 208, upon energizing, disconnects relay 206 from conductor 237 at armature 227. As a result of the connectin up of wiper 150 of the secondary switch S, relay 127 of the repeater R 13 connected up to the outgoing director impulse conductor, whereuponrepeating relay 127 energizes over the followmg circuit: from ground by way of armatures 414 and 417 of relays 381 and 382, Fig. 6, and their resting contacts, conductor 248, resting contact of armature 220 of relay 206, Fig. 4, and said armature, conductor 103, wiper 150, armature 145 and its working contact, and repeating relay 127 to battery. Repeating relay 127, upon energizing, closes a bridge across conductors 160 and 162 of the selector D at armature 136. whereupon line relay 163 of the selector D energizes and closes a circuit for release relay 164 at armature 174. Release relay 164, upon energizing, opens a point in the=circuit of release magnet 167 and prepares a circuit for vertical magnet 168 at armature 176, and at armature 175 places ground on release trunk conductor 161. In re onse to the connectin up of wiper 148 of t esecondary switch SS a connection isextended from armature 129 of line relay 125, by we of armature 143 and its working contact, wi er 148, conductor 101, armature 390 and 1ts resting contact, series relay 202, wiper 253 of the master digit control switch MDC, conductor 249, vertical magnet 229 of the oflice register OR; and the rig t hand Winding of the trunk tone machine TT to battery. Since armature 129 of line relay 125 of the repeater R is now attracted, and since that armature is connected with the lower heavy talking conductor through condenser 124, the calling subscriber hears the tone produced by the trunk tone machine T'l, Fig. 5, and knows that he may proceed with the call.

Before the establishin of the desired connection is proceeded with, the function of certain equipment shown in Fig. 4 will be taken up more in detail. For this purpose it will be assumed that the subscriber at substation A' is called away from his telephone after the receiver is removed, and that he does not replace the receiver on the hook. Now, when ground is placed on the common timed conductor. 209, Fig. ,4, by the associated cam springs, which occurs about every half minute or so, a circuit is closed for the lower winding of the marginally adjusted relay 201, which winding iscomposed of a small number of turns of wire having-a high spe-- cific resistance. Consequently, relay 201-energizes suflicienty to operatethe lightly adjusted armature 209, but not sufliciently to operate the more stifliy adjusted armature 210. Armature 209, upon being operated, grounds the upper winding of relay 201 by way of armature 215 and its working contact, and the resting contact of armature 212 and said armature. No current flows through the upper windingat this time, however, owing to the fact that it is grounded at both ter-' minals. When ground is removed from the common conductor 209, current flows through the upper and lower windings of relay 210 in series, whereupon the said relay energizes fully, and at armature 210'disconne'cts the timed impulse lead from its own lower winding, and extends it to relay 376by way of armature 218 and its resting .contact, and the normally closed'contacts controlled by armatures 389. When the next ground impulse 'is placed on conductor 209, a circuit is closed for relay 376. Relay 376, upon energizing,

locks itself to conductor 102 at armature 389, and at armature 390 disconnects conductor v101 from relay 202 and connects it to ground 7 connection through to the selector D and re instead. \Vhen this occurs, switching relay 126 in the repeater R, with which conductor 101 is connected, energizes and extends the leases the 'directorfin a manner to be described fully hereinafter. This is done so as Stepping1 to not tie u the director for d of time. he selectors, such as D,'are' provided ordinarily with timed supervisory It means (not shown which brings in a signal in case a selector is held lon er than apredetermined interval without time i. e., before'relay 376, Fig. '4, is enering 0 erated. It will be assumed now that the su scriber gize That bein the case, line relay -125;o 'f

the repeater R vious'ly traced circuit which includes series.

relay 202, Fig.4, and wi or 253 of the master digit controlswitch C. By the operat1on of vertical magnet 229, which receives ,nine .impulses of current at this time, the

een'ergizes in response to each interruption of its circuitat the calling wipers 260-263 inclusive, of the ofiice re 'isi ter OR are raisedstep-bystep until t ey stand 0 posite the ninth level of bank contacts. low acting'series relay 202 is energi zed during the entire vertical movement of the wipers and, upon energlzing, dlsconnects ground from-conductor 241 at armature 212,

thereby opening the locking circuit of relay 201 and allowing it to deenergize in case it is energized, and at armature-212 and its working contact closes a circuit for relay 203.

Relay 203, upon ener izing, prepares a circuit for relay 205 an for stepping magnet 251 of the master digit, control switch at ar-g mature 214.

At the end of the vertical movement of the switch OR, series relay 202 deenergizes and opens the circuit of relay 203 at armature 212. Relay 203, being slow acting, retains its armatureattra'cted for an interval. As a further result of the deenergization of relay 202,

it completes the circuit of steppingmagnet 251 of the switch MDC at armature 212.

magnet 251, upon energizing, advances t e wlpers 253 and 254 into engagement with the second set of bank contacts. Relay 205 energizes in multiple with stepping magnet 251, closes a locking circuit for itself and opens its initial circuit at armature 219; and at armature 218' disconnects the timed impulse lead extension from conductor 243 and connects it to relay 206, thereby preparing the director to call the monitoring operator in case the subscriber waits'too long between the dialling of the digits of the-number. After an interval, slow acting relay 203 deenergizes and opens the circuit of step ing magnet 230 of the switch MDC. The'dlrector is now in readiness to register the second oflice digit.

III

I I In order to explain how the call is trunked prescribed timelimit. That being the case,

relay 201 is energized and is locked up in the hereinbefore described manner the first time ground is placed on the common timed lead 209/ after the dialling of the first digit. The next time round is placed on the common timed concfuctor 209 acircuit is closed for rela 206 by way of armature 210 and its wor g contact, and armature 218 and ts working contact.- Relay 206, upon energizmg, places ground on release conductor 242 at armature 221; opens the circuit of repeating relay 127, Fig. 3, at armature 220 opens a point in the circuit of relay 376 at armature 222, disconnects ground from locking conductor 244 at armature 223, so as to allow relay 377, Fig. 6, to deenergize in the event that it i energized; and at armature 224 closes a circuit for relays 207 and 256 in series. In re sponse to the ground potential being placed on release conductor 242, release magnet 231 of the ofiice register OR energizes in series with the normally open contacts controlled by ofi normal s ring 252, whereupon the shaft and wipers o the switch OR are restored .to normal position in the usualmanner, the circuit of release'magnet 231 being opened by the switch-shaft when the latter reaches normal position; Likewise, release magnet 2509f the master digit control switch MDO energizes through off normal contacts 228 and restores the wipers 253 and 254 to normal. Relay 207 upon energizing, locks itself to the grounded conductor 102 at armature 225, and at armature 226 connects the resting contact of armature 224 to start conductor 247. Relay 256, Fig. 5, upon energizing in series with relay 207, connects up the four wiper conductors 264 267, inclusive, of the ofiice register OR to the group of special conductors 284-287, incluslve, respectively. The opening of the circuit of repeating relay 127 of the repeater R is for the purpose of allowing any partly established connection that might be set up to release. Since the connection extends only to the selector D, the line and release relays thereof are deenergized one after the other, whereupon the switch magnet.- WVhen ground is removed from the common conductor 209 after an interval of a second or so, relay 206 deenergizes and places ground on start conductor 247'at armature 224 by way of armature 226 and its working contact, and at armature 220 again closes the circuit of repeating relay 127 in the repeater R", whereupon the line and release relays of the selector D energize again. In response to ground being placed upon start conductor 248,

shaft steps up one step and is then restored to normal by the release .451 of the switch IDE to which the specia conductors 284-286,

inclusive, are j um red, is sent out in a manner to be describe fully herelnafter.

Assuming now that the calling subscriber does not wait too long between the calling of the various digits, and conse uently, that he calls the second digit 1 in the esired ofiice number before ground is placed on the common conductor 209 the second time after the dialling of the first digit in the number, one interruption is thereby produced in the circuit of line relay125 of the repeater R. Upon deenergizingin response to this interruption, line relay 125 sends an impulse of currentover conductor 101. This impulse of current extends by way of a path previously traced to wiper 253 of the master digit con- 'trol switch MDC, and thence by way of the second associated bank contact, conductor 246, and the contact of the tenth level spring 233 and said sprin to rotary magnet 230 of the ofiice register 6R. Rotary magnet 230, upon energizing, advances the wipers 260-263, inclusive, into engagement with the first set of bank contacts in the ninth level. By the combined action of slow acting series relay 202 and slow acting relay 203, an impulse of current is delivered, as before, to stepping magnet 251 of the master digit control switch at the end of the calling of the second digit, whereupon the wipers 253 and 254 areadvanced into engagement with the calling device in accordance with the first diglt 5 1n the subscribers number, five 1mpulses of current are delivered to stopping magnet 445 of the digit register DR by way 104, thereby I.

of a circuit previously traced to wiper 253 of the master digit control switch, and thence by way of the third associated bank contact and series relay 444. As a result, wiper DR is advanced step by step until it comes into engagement with the fifth associated bank contact. Slow acting series relay 444 is maintained energized duringthe stepping movement of the switch and maintains conductor 357 disconnected at armature 449. At the end of the stepping movement, relay 444 deenergizes and places ground on conductor 357 at armature 449 'DRf-DR, inclusive, are operated so as to allow the-first di it in the subscriber's number to be sent out. 'fhis ground potential comes through oil normal contacts 447 which became closed when thefswitch .wiper moved from its normal position. At the end of the series of impulses, the wi ers of the master digit control switch MD are advanced another step in the hereinbefore described manner, whereupon wi er 253 comes into engagement with the con uctor leading to the step connects ground from the conductors extending to the contacts of the bank of wiper 352 of the sequence switch S at armatures 385- 388, inclusive. As a further result of the placing of ground upon start. conductor 247,

.111 the first four contacts in'the bank of wiper 354 of the sequence switchS are grounded,

whereupon a ground potential is extended from wiper 354 to wiper 351, by way of cone ductor 370, and thence by way of conductor i 264 to the lower wiper 263 of the ofiice registerDB. Since wiper 263 is in engagement with the bank contact with which conductor 283 is connected, this ground potential extends by way of the associated IDF jumper Eli :- to the seventh impulse conductor 297. From the seventh impulse conductor 297, this ground otential extends to conductor 367 by way of t e resting contact of the upper armature of the seventh impulse counting relay 467, Fig. 7, and said armature; In response to the grounding of conductor 367, a circuit is closed for relay 380, Fig. 6, by way of the resting contact of armature 399 and. said armature. Relay 380, upon energizing, closes a circu't for itself independent of armature 399 and its resting contact at armature 412, connects up sending relay 381 at armature 411; and at armature 410 opens a point ,in the circuit of stepping magnet 350 and closes a circuit for slow acting relay 379. Relay 379, upon energizing, opens the initial circuit of relay 380 at armature 399, leaving relay 380 energized through armature 412 and its.

working contact; prepares a'circuit for stepping magnet 350 at armature 398; and at armature 397 places ground on locking conductor 368. Relay 381, upon energizing-the first time ground is placed on conductor 371 by the rotary interrupter I after armature 411 is attracted, closes a circuit for the lower the placing of ground upon winding of pick-up relay 382 at armature 413; and at armature 414 .removes ground from the outgoing impulse conduoQr 248. This latter operation does not have anys fleet, however, owing to thefact that conductor 248 is at this time maintained grounded through armature 417 and its resting contact. Pick-up relay 382, which is ofthe same marginal two-step type as relay 201, Fig. 4, energizes over its lower winding just enough to operate the lightly adjusted armature416, but not enough to operate the more stifiiy adjusfed' armatures 415 and 417. When relay 381 deenergizes, it removes the shunt from around the, upper windingof relay 382 at armature 413 and at armature 414 replaces ground on conductor 248. When this occurs, currenhflows through the two windings ofrelay 382 in series, whereupon the said relay energizes fully, thereby disconnecting arma ture 413 of sending relay 381 from its own windingsand extending it by way of conductor 369 to armature 477 of the first impulse counting relay 461, Fig. 7. As a further result of the energization of relay 382, it disconnects ground from conductor 248 at armature 417, leaving the said conductor grounded only through armature 414 and its resting contact The next time relay 381 energizes, it removes ground from conductor 248 at armature 414, thereby opening the circuit of repeating relay 127 of the repeater R, Fig. 3, and at armature 413 closes a circuit tor the lower winding of the marginal two-step counting relay 461, whereupon relay 461 energizes part way and grounds its upper winding at armature 476. When relay 381 deenergizes again, it opens the initial circuit of relay 461 at armature 413 and at armature 414 replaces the ground potential on conductor 248. When this occurs, relay 461 energizes fully; disconnects the first impulse conductor 291 from conductor 367 at armature 475; and at armature 477 extends conductor 369 to the corresponding armature of counting relay 462. Asa result of the ground potential being replaced on conductor 248, the repeatingrelay of the repeater R energizes again. As sending relay 381 energizes and deenergizes, one ofthe impulse counting relays. Fig. 7, pullsepart way up for each energization and all the way up for each de energization thereof and. upon each energiza of relay 381, ground is removed from the outgoing impulse conductor 248 at armature 414. This continues in the manner described until the seventh impulse counting relay 467 pulls all the wayup as it does upon the eighth deenergization of sending relay 381, at which time ground will have been removed from the outgoing impulse conductor 248 seven times. .Relay 467, upon energzing fully, disconnects ground from conductor 367 at its upper armature, whereupon relay 380, Fig. 6, deenergizes; disconnects impulse relay 381 at armature 411 while the upon the switch wipers are advanced into latter relay is still deenergized; and at armas en'gagement with the second set of bank conture 410 opens the circuit of slow acting relay 379' and closes a circuit for stepping magnet 350 of the sender S by way of armature398 and its workin contact. Relayl 379 is slow actingand is adjusted so as to enough to give the proper space between digits. Stepping magnet 350, of the sender S, upon energizing, merely advances the associated pawl into engagement with the next notch in the ratchet wheel and does not move the wipers.

-In the repeater B, Fig. 3, repeatmg relay 127, upon deenergizing in response to each of the seven interruptions produced in its circuit by sending relay 381 as described above,

- opens the circuit of line relay 163 of the selector D at armature 136. Each time line relay 163 deenergiz'es, it closes the following circuit for vertical magnet 168 From ground by way of the resting contact of armature 182 and said armature, armature 174 and its resting contact, armature 176 and its working contact, series relay 165,- and vertical magnet 168 to'battery. By the operation of vertical magnet 168, the switch wipers 184 186, inclusive,are lifted step by step untll they stand opposite the seventhlevel of bank contacts. Slow acting series relay 165 1s maintained energized in series with vertical -magnet 168 during the entire vertical movement. Upon the energization of series relay 165 and the closure of off normal contacts 173, which occur on the first vertical step, a

circuit is closed from release trunk conductor 161 through armature 177 and its working contact, oflt' normal contacts 173, and interrupter contacts 171, for stepping relay 166. Stepping relay 166, upon energizing, closes a locking circuit for itself at armature 17 8 and at armature 17 9 prepares a'circuit for rotary magnet 172.

At the end of the vertical movement, relay 165 deenergizes and completes the circuit of rotary magnet 172 at armature 177. Rotary magnet 172, upon energizing, advances the wipers 184-186, inclusive, into engagement with the first set of bank contacts in the seventh level, and near the end of its stroke, opens the circuit of stepping relay 166. opens the circuit of rotary magnet 178 at armature 179, Whereupon rotary magnet 172 decnerizes and closes its interrupter contacts again.

in case the trunk terminating in the.first set of bank contacts is idle, switching relay 167 energizes immediately. However, if the trunk is busy. switching relay 167, being short circuited by the ground potential found on the test contact thereof by test wiper 185,

does not energize. In this case, stepping magnet 166 energizes from ground on the busy test contact and again closes the circuit of rotary magnet 172 at armature 179, whereold up long tacts. This alternate operation of stepping magnet 166 and rotary magnet 172'continues until an idle trunk is reached, whereupon switching relay 167, beln no longer short clrcuited, energizes in series with stepping relay 166, the latter relay not energizing at thistime on account of the high resistance of Switching relay '167, disconnects ground from armatures 180 and 183 disconnects conductors windings of line relay 160 and 162 from the 165'and extends them by wa of wi ers 184 and 186 to the line relay of the trun seized, whereupon the last named line relay and its associated release relay energize and the latter places round on the release trunk conducto'r of t 1e trunk, thereby establishing the usual holding circuit for switching relay 167 before release relay 164 has had time to deenergize.

At the end of the predetermined interval, relay 379 deenergizes; prepares a circuit for relay 380 at armature 399; removes ground from conductor 368 at armature 397, whereline relay 163 at armature. the circuit of release" lays in Fig. 7 as are energized, deenergize; and at armature 398 ping magnet 350. Stepping magnet 350 now deenergizes and'advances the wipers 351- 354, inclusive, of the sender S into engagement with the second set of bank contacts. \V1per 351, upon being advanced, disconnects the grounded conductor 370 from conductor 264 and connects it to conductor 265, thereby removing the ground from the lower or first digit wiper 263 of the ofiice register OR and extending it to the second digit wiper 262. Since wiper 262 is in engagement with the bank contact with which conductor 282 is connected, and since conductor 282 is jumpered to the second-impulse conductor 292, ground is placed on the latter. This ground potential extends by way of conductor 292 and the resting contact of the upper armature of the second counting relay 462, Fig. 7, and said armature to conductor 367. In response'to the ground potential being placed on conductor 367, relays 380 and 379 energize one after the other as in the preceding case, and relay 381 begins to vibrate under the control of the interrupter I, each deenergization after the first resulting in the removal of the ground potential from the outgoing impulse conductor 248, 382 being operated upon the firstenergizati on of relay 381. Since the controlling ground potential is coming in through the upper armature of the second counting relay 462 at this time, ground is removed from conductor pick-up relay- 367 upon the energization of the second counting relay 462, at which time the ground potential willhave been removed from the outgoing impulse conductor 248 twice, thereby sending out the second oflice digit 2.

The seconddigit of the oflice code is reported by relay 127 in the repeater R, Figure 3., the same as the first digit, and the second selector to which the connection has been extended by the first selector D is operated in the usual manner to trunk the call to the distant oflice in which the called line is located. When ground is removed from conductor 367, relays 380 and 379 fall back'one after the other in the order named, thereby sending an impulse of current to stepping magnet 350 of the sequence switch S upon the deenergization of relay 379, which causes the wipers of the sequence switch to be advanced into engagement with the third set of'bank contacts. When this occurs, wiper 351 disconnects the grounded conductor 370 from conductor 265 and connects itto conductor 266, thereby grounding the third digit wiper 261 of the office register OR. Since wiper 261 is in engagement with conductor 281, and since conductor 281 is jumpered to the third digit skip conductor 305, there being no third digit in the ofiice code, this ground potential is extended to conductor 305. When conductor 305 is grounded, stepping magnet 350 of the sequence switch S energizes tlirough wiper 352, which is standing on the bank contact with which conductor 305 is connected, and interrupts its own circuit at contacts 349, whereupon it immediately deenergizes and advances the wipers of the seuence switch into fourth position. When t is occurs, wiper 351 disconnects the ground potential from conductor 256 and places it on conductor 267, thereby grounding the fourth digit wiper 260 of the ofiice register OR. Since the oflice to which the call is going is an automatic ofiice, conductor 280 is jumpered to conductor 302. Consequently, the ground potential extends by way of conductor 280, the associated IDF jumper, conductor 302, normally closed contacts controlled by armature 392, and relay 377 to battery. Relay 377, upon energizing, locks itself to the grounded conductor 244 and opens its initial circuit at armature 392; places ground on the ninth position contact of sequence switch wiper 353 at armature 393, so as to opt erate the switch-through relay 376, Fig. 4,

when sequence switch wiper 353 reaches the ninth position instead of the tenth position for which it is normally set; and places ground on conductor 306 at armature 391', thereby causing the sequence switch S to advance automatically from the fourth to the fifth position.

When the wipers of the sequence switch S reach the fifth position, wiper 354 encoun-- ters the conductor 357, which conductor is grounded only in case the calling subscriber has called the first digit in the esired subscribers number. Assuming the first digit 5 in the subscribers number to have been fifth associated bank contact in accordance with the first digit 5 in the desired subscribers number, as hereinbefore explained, the above mentioned ground potential is extended to the fifth impulse conductor 295 and extends from thence to conductor 367 by way of the res ng contactof the upper armature of the fi h counting relay 465 and said armature. In response to the ound potential being placed onconductor 367, therelay sender starts to operate in the previously described manner and since the ground potential is being supplied toconducto'r'367 by way of the fifth impulse conductor 295, five impulses are sent out p at armature 414 at this time. Atthe end of the series of impulses, round is removed from conductor 367, upon t 1e energization of counting relay 465, whereupon relays 380 and 378 fall back one after the other in the usual manner, and the wipers of the sequence switch are advanced into the sixth position. V

In the sixth position of the sequence switch S, starting ground is supplied to wiper 354 by the digit register DR by way of conductor 359, and is extended by wiperf351 of the sequence switch to wiper 452 of the di it register DR by way of conductor 358. ccordingly, the second digit 6 in the subscribers number is sent out in the same manner'as the first digit 5, after which the wipers of the sequence switchare advanced into seventh position.

In the seventh position of the sequence switch S, ground is supplied to wiper 354 by the digitfregister DR" by way of conductor 361, and in turn is supplied to wiper 453 of the digit register DR by wiper 351 of the seuence switch S by way of conductor 360.

ister DR, F ig. 7 by.

onse uently, the third digit 7 in the subscriber s number is sent out in the usual manner, after which the wipers of the sequence switch are advanced into the eighth position.

Similarly, inthe eighth position of the sequence switch S,'ground is su plied to wiper 354 by the digit register DR hy wa of conductor 363, and in turn is 5 lie to the wiper 454 of the digit register R by wiper 351 of the sequence switch by way of conductor 362. Consequently, the fourth digit 8 in the subscribers number is sent out in the usual manner, at the end of which the wipers ninth position in the previously described manner. 1 Responsive to the transmission of the four digits in the subscribers number, two secontact, and relay 126 relay 126 is that it disconnects the callin lectorsand a connector in the distant automatic ofliee are operated in the usual manner to complete the connection to the called subscriber s line. I

When the wipers of the sequence switch reach the ninth position, a circuit is closed for switch-through relay 37 6, Fig. 4, as follows: from ground by way of tlge working'contact of armature 393 and sai i armature, n nth contact in the bank of sequence switch wiper 353 and said wiper, conductor 243, armature 222 and its resting contact, normally closed contacts controlled by armature 389, and switch-through relay 376 to battery. Relay 376, upon energizing, locks itself to conductor 102 and opens its initial circuit at armature 389, and at armature 390 disconnects the 1ncoming impulse conductor 101 from relay 202 and connects it to ground instead. When this occurs, relay 126 in the repeater R enerizes over the following circuit: from ground By way of the working contact of armature 390 and said armature, conductor 101, wiper 148 of the secondary switch SS, working contact of armature 143 and said armature, armature 129 of line relay 125 and its working to battery. Relay 126, upon energizing, locks itself to release trunk conductor 161 at armature 133; connects release trunk conductor 122 of the repeater R with release conductor 161 of the selector S at armature 132; and connects the line conductors 121 and 123 of the re eater R with line conductors 160 and 162 o the selector D at armatures 130 and 135. The adjustment of the contacts of relays 126 is such that armatures 131 and 134 break away from their resting contacts just after armatures 130 and 135 make contact, thereby disconnecting line relay 125. The last circuit change produced by the local bridge from across conductors 160 and 162 at normally closed contacts controlled by armatures 130 and 135, thereb leaving the established connection under the direct control of substation. The resistance 152 is include in-the local bridge for the purpose of preventing unduly loud clicks when the local bridge and the subscribers loop are placed together and separated.

In the director as a further result of the sequence switch S advancing'to ninth position, wiper 354 engages conductor 365 which is the conductor that is grounded when the series relay of the fifth digit re ter DR comes to rest after the operation 0 the said switch DR. In this case the digit register DR has not been operated, but conductor 365 is normally grounded through armature 394 of re contact, and the ground lay 378 and its restin potential is extende through the ninth contact of wiper 354 and said wiper, conductor 370, wiper 351, and conductor 364 to wiper 455 of the digit register DR. Since wiper 455 of the digit register DR is not operated, the placing of ground thereon-has no efiect at this time. However, .conductor364 is normally connected to the first impulse conductor 291 by way of the resting contact of armature 396 of relay 378 and said armature. Consequently, this ground potential extends from conductor 291 to conductor 367 by way of the resting contact of armature 475 of the first counting relay 461, Fig. 7, and the relay sender starts to send out the digit 1. The operation of the sender at this time has no etfect, however, for the reasonthat the switch-over occurs immediately upon the sequence switch being advanced to ninth position, as hcreinbefore explained, and the control of the connection is removed from the outgoing repeating relay 127 in the repeater R before the first impulse comes along.

Inthe repeater R, Fig. 3, line relay 125 deenergizes in response to being cutoff by relay 132 at armatures 131 and 134, as pointed out above, and opens the initial circuit of relay 126 at armature 129, leaving relay 126 energized through its locking circuit which is closed at armature 133. As a fur ther result of the deenergization ofline relay 125, it opens the circuit of the slow acting line relay 137 of the secondary switch SS at armature 128. Relay-137, upon deenergizing, opens the circuit of switching relay 138 at armature 140, whereupon switching relay 138 deenergizes and disconnects wipers 148151, inclusive. By this operation, the ground potential is removed from conductor 104 of the director trunk, whereupon relay 208, Fig. 4, deenergizes but does not perform any particular function at this time. As a furiher result of the removal of the ground potential from conductor 104, the ground potential is removed from starting conductor 247, whereupon relay 375, Fig. 6, deenergizesand grounds all the contacts in'the bank of wi er 352 of the sequence switch S. When this occurs, the wipers of the sequence switch are automatically advanced through its remaining positions and into the first position by the buzzer like action of the stepping magnet 350. \Vhen ground is removed from conductor 102 of the director trunk, relays 376, 204, and 205, Fig. 4, deenergize, and relay 204 places ground on release conductor 242 at armature 216, whereupon the oifice register OR and the switch MDC are released in the usual manner. Conductor 242, it will be noted, is ex tended across the top of Fig. 7 anda lead is taken from the'said conductor to the lower off normal contacts of each of the digit registers DR-DR, inclusive. Accordingly, the release magnets of such digit registers as are off normal energize and restore the digit mg substation A by the removal of the groundpotential from the release trunk conductor by the switch to which connection has been extended. When this occurs, the switching relay 167 of the selector D, relay 126 of the repeater R, and switching relay 110 of the line switch C deenergize. The deenergizaiion of relays 110 and 126 restores conditions in the line switch G and the repeater R to normal and the deenergization of switching relay 167 of the selector D results in a circuit being closed for release magnet 169, which circuit includes armatures 182, 174, and 176,

and off normal contacts 170. The selector D is restored to normal posiiion in the usual manner upon the energization of release magnet 167, the circuit of release magnet 167 being opened at 06? normal contacts 170 by the switch shaft when the latter reaches normal position.

It will be assumed nowthat the subscriber at substation A desires to converse with a subscriber whcse line terminates in the manual party line oflice 92, whose line number is 1234, and whose station number is 5. It will be assumed further that, when the subscriber removes his receiver, his individual line switch C selects the trunk leading to the repeater R, and that the secondary switchhereinbefore described results.

In response to the calling of the second ofiice digit 2, the wipers 260-263, inclusive, of the office register OR are advanced into engagement with the second set of bank contacts in the ninth level. By the operation of rotary magnet 251 of the master digit control switch MDG, the wipers thereof are advanced another step, whereupon the opcrating circuit is extended to stepping magmanner to register the digits called, the necessary control being exercised by the master digit fiontroller MDC as hereinbefore exam P When the ground potential is placedon the start conductor 247 as pointed out above, ground is'extended through the first contact in the bank of wiper 354' of the sequence switch S to conductor 370, and. thence by way of wiper 351 of the sequence switch S, and conductor 264 to the first digit wiper 263 of the oifice register OR. From an inspection of the drawings, it will become apparent that the first three contacts from the bottom of the set with which the wipers of the oflice register are now in engagement, or the contacts in which the conductors 277 2'7 9, inclusive, are terminated, are jumpered so as to send out the ofiice code 850. Consequently, the ground potential on wiper 263 is extended over conductor 279 and the associated IDF jumper, tothe eighth impulse conductor 298. That being the case, the relay sender operates in the previously described manner to send out the first digit 8 in the ofiice code, after which an impulse of current is delivered to stepping magnet 350 of switch S, whereupon the wipers are advanced into second position and ground is placed on the second digit wiper 262 of the ofiice register OR. This ground potential extends by way of bank conductor 278 and the associated IDF jumper to the fifth impulse conductor 295. Consequently, the second digit 5 in the office code is sent out by the relay-sender, after which the sequence switch S is advanced into third position and the ground potential is extended over the third digit wiper 261, the bank contact with which it is in en agement conductor 277, and the associated IDF jump- Gil er to the tenth impulse conductor 300, whereupon the third digit 0 in the oflice code is sent out.

Responsive to the transmission of the three oflice digits, the call is trunked through the automatic network to the desired. manual office, where call indicating apparatus is prepared for the reception of the digits in the called subscribers number.

WVhen the wipers of the switch S are advanced into fourth position after the sending out of the third digit in the oifice code, ground is placed on the fourth wiper of the office register OR, and is extended from thence by way of the bank contact with which it is in en agement, conductor 276, the associated ID? jumper, ring digit conductor 303, the normally closed contact-s controlled by armature 395 of relay 378, and relay 378 to battery. Relay 378, upon energizing, closes a locking circuit for itself and opens itsv initial circuit at armature 395*, disconnects ground from conductor 365 at armature 394 so as to cause the sender to wait for the operation of the fifth digit register DR; disconnects the first impulse conductor 291 from conductor 364 at armature 396, so as to leave the sender free to send out the 101-104, inclusive.

digit set up on the digit register DR" and at armature 394 places ground on con uctqr 306, thereby causing the switch- S to advance au tomat1- call from its fourth tb its fifth posltion.

The sender now sends out the digits set up on the digit registers DRDR, inclusive, in thehereinbefore described manner, thesequence switch S .being advanced=automatically in the usual manner at the end of each digit. It will be noted that since relay 377 is not energized at this time, ground-1s not placed on conductor 243 of wiper 353 of the sequence switch S until the sequence switch 1s advanced into its tenth position. Consequently, the director does not switch through until the fifth or party selectingdi it has been sent out .and the sequence switc1 has been advanced to tenth position.

The five digits in the'called number are registered by the call indicator in use at the manual oflice and at the proper time are displayed to an operator, who completes the connection in the usual manner.

When the sequence switch reaches tenth position, conductor 243 is grounded, whereupon the' director switches through in the hereinbefore described manner.

It will be assumed now that the subscriber at substation A desires to converse with a subscriber in the individual line manual office 93, whose number .is 1234. It will be assumed further that when the subscriber removes his receiver, the individual line switch C selects the trunk extending to the repeater R, and that the secondary switch SS selects the director trunk comprising conductors That being the case, the oflice register OR is raised to the ninth level in response to the'dialling of the first oflice digit 9, and is rotated three steps in response to the dialling of the second digit 3, and the digit registers DRDR inclusive, are operated in response to the next four digits dialled and register such digits.

The sender starts to send out the ofiice code at the end of the dialling of the second ofiice digit in the usual manner. the oflice codedesired in the present case is 859. Accordingly, the conductors 275, 274, and 273 of the ninety-third set of bank contacts of the office register OR are jumpered to the eighth, fifth, and ninth impulses conductors, respectively. Since the office to which the call is going is an individual line manual ofiice, no special relay need be pulled up, and the fourth conductor 272 of the set is umpered to the fourth digit skip conductor digit 9 in 306. When the fourth digit wiper 260 of the ofiice re ister OR is grounded by the sequence switch S after the sending out of the third by way of conductor 272 and the associated IDF jumpered to the fourth digit skip conductor 306, whereupon the wipers of the send- 1,aes,724,

usual manner, the sequence It is assumed that the ofiice code, ground is extended er are advanced automatically into the fifth position.

The sender now sends out the digits 1-4,

inclusive, of thesubscribers number in the switch S being advanced one step after each di 't.

When the sequence switch reaches the ninth position, ground is supplied to conductor 370 by way of armature 394 of relay 378 and its resting contact, ninth contact in the bank of wiper 354, and wiper 354k This ground potential is extended by wiper 351 to conductor 364 and extends from thence to the first impulse conductor 291 by way of the resting contactof armature 396 and said armature. Gonsequently, the relay sender proceeds to send out the digit 1, this digit being added automatically by the director in order to switch the call indicator at the manual oflice int'o displaying position for reasons hereinbefore given. As soon as the-digit 1 has been sent out, the sequence switch S is ad,- vanced into tenth position, whereupon ground is placed upon conductor 243 by way of wiper 353, andthe director switches thru as a result.

In order to explain the operation of the director in calling the long distance operator, it will be assumed that the subscriber at substation A desires to call erator. It will be assumed further, that the connection is extended upon the removal of the receiver at substation A.to the director trunk which comprises conductors 101-104, inclusive of the secondary switch SS.

When the calling subscriber operates his calling device in accordance with the digit 0, which digit is the one assigned to the long distance operator, the ofiice register OR, Fig. 5, raises its wipers opposite the tenth level of bank contacts, which is the level in which the upper set of contacts shown in Fig. 5 is located. It will be remembered that rela s 202 and 203, Fig. 4, are energized during t e vertical movement of office register OR. Also, when the tenth level is reached, the switch shaft operates the tenth level springs 233-235 inclusive. Spring 233, upon being operate disconnects the rotary magnet op erating lead 246, so as to remove the rotary movement of the switch from under the control of the calling subscriber. Spring 235, upon coming into engagement with its associated contact, places ground upon the second contact in the bank of wiper 254 of the master the long distance op-.

- above, it places ground on the usual circuit for stepping magnet 251 of the switch'MDC A branch of this circuit extends by way of the working contact of armature 213- and the said armature, conductor 238, spring 234 and its upper contact, and rotary magnet 230 to battery. Stepping magnet 250 of the master digit control switch 254-is moved into engagement bank contact, as described start conductor 247, conductor 239 having been grounded by tenth level spring 233. Consequently, the relay sender starts to send out the code necessary -to trunk the call to the long distance operator.

iinpul e conductor 296.

he code in this case is assumed to be 46. Ac ordingly conductor 271, Fig. 5, is jumpere to-the fourth impulse conductor 294 an conductor 270 is jumpered to the sixth In order to cause the director .to switch thru after the calling of the second digit 6 in-the code, conductor 269 is jumpered to the codethe sequence switch Fig.

number switch conductor 301. That being the case, when the third digit wiper 261 of the ofiice register OR is ounded by wiper 351 of 6. after the second digit 6 is sent out, the ground potential extends by way of conductor 269, the associated IDF jumper, code-number switch conductor 301, and the third contact in the bank of sequence switch wiper 353, to switch conductor 243. Consequently, the director switches through in the hereinbefore described manner.

The operation of the improved director when used by a paystation subscriber will now be considered. For this purpose, it will be assumed that the subscriber at substation A desires to make a call. The substation A, as before explained, is of the paystation type and the subscriber thereat is instructed to deposit a coin before dialling. \Vhen the receiver is,-

removed, a bridge is placed across line conductors 5 and 6, whereupon line relay 6 of the line switch C energizes and closes the usual circuits at armatures' -13 and 14, whereupon the line switch C selects an idle trunk, which trunk, it will be assumed, is the one comprising the conductors 18:20, inclusive.

energizes when an idle upon the energization of line relay 8, in case the wipers 15-17, inclusive, are standing onan idle trunk Switching relay. 7 trunk is reached or immediately its resting contact,

interval, slow acting relay when the can 10 -12, inclusive, switches the connection is initiated, and at armature through to the trunk comprising conductors 15-20, inclusive. There is a bridge across conductors 18 and 20 of repeater R, conductor 20 being grounded through armature 47 and lower left hand winding of the repeating coil, diiferential relay 32, and conductor 18 being connected to battery by way ofarmature 44 and its resting contact,upper left hand wind-, ing of the repeating coil, upper winding of differential relay 32, and hue relay 35. Consequently, line relay 35 energizes. Differential relay 32, however, until the circuit\has been unbalanced by the depositing of a coin at the substation. Line relay 35, upon energizing closes acircuit for reand the lower winding of does not energize lease relay 34 at armature 60. Release relay 34,11ponenergizing,preparcsacircuitforrelay 35, at armature 57, and at armature 58 places ground on conductor mally closed contacts controlled by armature 64 so as to establish the usual holding circuit fbi the line switch C. It will be noted that a V 78, thereby grounding release trunk conductor 19, by way of the nor- J circuit is closed for the lower winding of the electro polarized relay 31 from release trunk conductor 19. Relay 31, however, is marginally'adj usted and doesnotenergize at this time on account of the resistance 50. As a further result of the'energization of release relay 34, it closes a circuit for line relay 85 of the sec ondary switch SS at armature 56. Line relay 85, uponrenergizing, disconnects release trunk conductor 76 of the associated selector from release conductor 190i the repeater R at armature 88 closes a circuit for switching relay 86 and stepping magnet 93 in series at armature 87 closes the usual test circuit. The secondary switch SS now selects an idle trunk in the usual manner, which trunk, it will be assumed, is the one comprising conductors 101-104, inclusive. Switching relay 86, upon energizing when the idle trunk is found, opens the test circuit and grounds wiper 95 at armature 90, and at- armatures 89, 91, and 92 connects up the wipers 94, 96, and 97, re-' spectiveiy. When this occurs, lay 37 energizes from ground on the outgoing impulse lead 103 of the trunk, through Wiper 96 and armature 91v and its working contact, and at armature 67 closes a bridge across the conductors 75 and 77 leading to the associated first selector, whereupon the said selector is prepared for operation in the usual manner and release trunk conductor 7 6 is grounded. .As a result of the ground potential being placed on wiper 95 of the secondary switch SS by armature 90, relay 204 in the director,,Fig. 4, energizes with the hereinbefore described results. The calling subscriber now hears the tone produced by the trunk tone apparatus TT, Fig.5, and knows that he may start to dial the desired num-

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