US1760823A - Automatic telephone system - Google Patents

Description

May27, 1930. H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed March 19. 1928 7 Sheets-Sheet Inverdur- Herbert-P'I-fiiendl May 27, 1930. H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed March 19. 1928 7 Sheets-Sheet EIIU May 27, 1930. H. M. FRIENDLY 1,760,823

- AUTOMATIC TELEPHONE SYSTEM Filed March 19. 1928 7 Sheets-Sheet 3 May 27, 1930. H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed March 19. 1928 7 Sheets-Sheet M90, PM u F knrmukkkkmukk w vmN 1mm. I |UHHH o mww, M90. D

m nf rLukmmmmmLumum NQQ 1:. m n F 1%4JJJJJ MW I a ll a Herb 715 May 27 1930. H. MIFRIENDLY 1,760,823

AUTOMATIC TELEPHONE SYS TEM Filed March 19. 1928 7 Sheets-Sheet 5 -Inven1ur- HErhEPi-PI-FriEindlg @aw A May 27, 1930. H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM 7 Sheets-Sheet Filed March 19, 1928 mm W Ami

Patented May 27, 1930 meas es 1 rent HERBERT 1a. FRIENDLY, OF CHICAGO, ILLINOIS AUTOMATIC TELEPHONE sYs'rEM Application filed March 19, 1928. Serial No. 262,626.

The present invention relates to telephone systems; more particularly so-called automatic or machine switching telephone systems.

' General objects I The general objects of the presentinvention are to enable a subscriber of the auto matic telephone system, who contemplates temporarily leaving the location of his telephone, to directively set central ollice apparatus or call forwarding equipment associated with his line through the agency of his automatic calling device dial on his telephone so that in case any calls are thereafter directed to his line, the latter said calls will be further extended or forwarded to a predetermined random subscribers line or other line of the system. That is, forexample, a subscriber before leaving the premises may remove the receiver of his telephone as if to initiate a call, and then operate his calling device dial by placing his fore-finger in a spe cific depression finger-hold of the dial and then draw the dial until his finger encounters the finger-stop, so that when the dial is released it will send a series of eleven open impulses. After the dial has restored, he will restore the receiver, leaving the central office call-forwarding equipment in the set conditicn.

To unset the said call-forwarding equipment, he will similarly operate the dial from another specific finger-hold depression, so that when it is released it will send a series of twelve open impulses. After the dial has restored, he will restore the receiver, leaving the central oilice call-forwarding equipment in the normal unset condition.

However, in accordance with the present invention, in the event that the before-mentioned (normally) predetermined line is not the line to which it is in the particular instance desired to have the calls forwarded to,

the predetermined line may be directively changed. The latter is accomplished by annexin the telephone number of the line to which it is desired to have calls forwarded. to in the particular instance, forthwith after operating the dial to effect the series of eleven open impulses mentioned. The receiver Wlll then be restored to the switch-hook, leaving the set line in condition forforwarding calls directed to it to the specific line indexed by the number annexed after primarily set ting the line by the series of eleven open impulses. That is to say, not only is there a normally predetermined line to which calls may be forwarded when a set condition exists on a line called, but this normally predetermined line may be temporarily changed to a random desired line ofthe exchange.

In connection with the last foregoing, relating to changing from the normally predetermined line to a random desired line to which calls willbe forwarded under the set condition, when the subscribers line is to be unset it is done by removing. receiver as in initiating a call thereon, and then sending a series of twelve open impulses. The latter elfaces not only the said set condition accomplished responsive to the first said sending of the eleven open impulses,but it also effaces the substituted random desired line and ma ders the normally predetermined line subject to being called when the subscriber next causes his line to be set by sending theseries of eleven open impulses and withoutannexing any digits,

It will thus be'perceived that the present invention is adapted for use in connection with a subscribers telephone line wherein it may be desired to have calls which may be .made thereto, in the absence of the subscriber, forwarded to a desired random line of the exchange as may be predetermined by the subscriber when he sets his line for forwarding calls made thereto. That is, a residence subscriber may leave his residence and go to the residence of some other random subscriber, and desires that all calls made to his tele phone be forwarded to the telephone of the subscriber where he will be found. Moreover, a business establishment may wish to have some employee respond to after business hours calls. The line will, therefore, be F set to forward calls made to it ,to' any desired telephone of an employee, perhaps a different employee being selected for succes sive days. That is, there may be a predetermined employee who will be charged with responding to such calls responsive to the normal setting of the set relay, while this may at will be changed to a random telephone line by simply annexing the number of the latter telephone line, after normally setting the line for forwarding.

The set condition may be at will efi'aced. It will be effaced at a predetermined time automatically. Of course, a manual setting may be made in the central office, in the event the subscriber neglected to set the line, and a duly authenticated request from him is made for such setting.

General operation Reference is made to my pending applications for patent Ser. No. 218,605, filed Sept. 10, 1927; Ser. No. 241,793, filed Dec. 22, 1927 Ser. N o. 257 ,480, filed Feb. 27, 1928, and Ser. No. 259,047, filed March 5, 1928. These pending applications are directed to telephone systems and apparatus having objects broadly as set forth in the foregoing statements. The present invention has features believed to be novel but not disclosed in the said cited pending applications. Some of these latter said novel features will be specifically described and pointed out in the present specifications, while other said novel features will be apparent in view of the disclosures specifically set forth in the specifications and drawings.

Among the features of the present invention believed to be novel are:

(1. Means whereby after the subscriber has caused his line to set for forwarding calls to the predetermined line by operating the calling device dial in accordance with the setting finger-hold, thereby sending a series of eleven open impulses, he can again operate his calling device dial in accordance with the said finger-hold and thereby cause a connection to be linked from the subscribers line now set to the said predetermined line. The response on the latter said line will verify the set condition of the subscribers line. The subscriber can then hang up his receiver, leaving his line in the set condition, the said linked connection being at the same time destroyed.

6. Means whereby after the subscriber has caused his line to be set'for forwarding calls to the said predetermined line, he can thereupon operate his calling device with correspondence to the digits of a desired random line of the exchange, and thereby change the primary setting with respect to the said predetermined line to an arbitrary setting for the random line indexed by the digits anneXed by the dial after sending the series of eleven open impulses to set the subscribers line, and he can further thereupon again operate his calling device in accordance with the said setting finger-hold and thereby cause connection to be linked from his line to the said random line. The response on the latter said line will verify the set condition of thesubscribersline. The subscriber can then hang up his receiver, leaving his line in the set condition, the said linked connection being at the same time destroyed.

a. Means whereby the operation set forth in paragraph b as tothe linking of the call can be alternatively elfectuated responsive to sending any digit from 1 to O in place of sending the series of eleven open impulses.

d. Means whereby if a connection is caused .to be linked from the subscribers line, as set forth in paragraphs a, b, and 0, when the response occurs on the line to which the connection has been linked, andwhich is the line to which calls made to the subscribers line will be extended, when the response occurs the direction of current traversing the receiver on the subscribers line will be reversed in direction. This reversing of current may control supervisory signals or meter or coin-box toll devices, it being old in the art to control such devices by current reversal. However, it is believed that the means disclosed by the present invention for accomplishing this reversal is novel. 7

6. Means whereby the unsetting of the set condition of the set subscribers line can be effaced by sending a series of twelve open impulses efi'ectuated by operating a specific finger-hold'on the dial of the calling device, which latter said finger-hold is located next to the setting finger-hold for sending a series of eleven open impulses. This means includes off-normal springs on the first se-" lector operated at the eleventh and twelfth levels when the wipers rotate-in on the respective levels. The eleventh level said offnormal springs cause minus battery to be applied over an operating conductor to effect the said set condition. The twelfth level said off-normal springs cause plus battery to be applied over said operating conductor to effect the effacement of the said set condition. The said operating conductor leads through the winding of a polarized relay to ground, so that the armature of the latter said relay will operate to close a ground path to a specific operating conductor for setting and a specific said conductor for unsetting, depending upon if minus or plus battery is applied over the said operating conductor responsive to the operation of the dial for setting or unsetting.

f. An impulse sending mechanism is shown (Fig. 5)- that is common to a plurality of subscribers lines, as distinct from the impulse insure that only the testing Wiper will bear appreciably on its co-operating bank terminals to effect conductive relation, while the remaining wipers'will either remain out of conductive engagement with co-operative This device includes a shaft (Fig. 8) with a slip coupling and a magnet for attracting the shaft, andall wipers excepting the said test wiper, endwise wherein the said coupling will permit the shaft to move endwise without affecting the tension between the test wiper and its co-operative bank terminal it is then resting upon.

Drawings With reference to the accompanying drawings Fig. 1 shows a calling telephone A leadingin to a line switch B. It also shows a set relay 0 for changing the so-termed normal conductors from the line leading to the line switch B to the corresponding terminals accessible from line finder switch F in Fig. 8. Theindicated connector D normally has access to the line leading to telephone A.

Fig. 2 shows a first selector E of a group accessible from line switch B. It also indicates a calling telephone A leading to a line switch L the latter having access to first selector B second selector C third selector J and connector D in Fig. 1 in sequence, to complete a call from telephone A in Fig. 2 to the telephone A in Fig. 1.

Fig. 8 shows a line finder switch F involving auxiliary apparatus, the said switch having access to terminals of a plurality of lines which may be called through connector D inFig. 1, or random connectors in the exchange oiiice containingconnector D wherein contact springs of a set relay similar to relay 0 are interposed. Each said line accessible from the switch'F has a line relay as shown on the left aligned with the relays of the said switch. l'Vhen the switch F operates and seizes a set of its bank terminals corresponding to a line called, its lower group of fifteen wipers are then co-operative with bank terminals which correspond to the line to which said set relay 0 belongs. The said switch F has an impulse sending mechanism individual to it and shown in Fig. 5. i

.Fig. 1 shows a first selector G companion to and individual to the switch F in Fig. 3. The

3 first selector Ghas access to other switches in common with first selectorE in Fig. 2.

the digit setting switches for the first three digits of the number (of five digits) of the line to which calls directed to theline leading to telephone Aare topbe forwarded to.

Fig. '7 shows switches K and L, being the digit setting switches for the last two digits of the number of the line to which" calls directed' to the line leading to telephone A are to be forwarded to. Fig. 7 also shows the switch M which distributes to the switches H to L. V r

Fig. 8 shows the details of the wiper shaft for switch F in Fig. 3, referred to inthe fore- 7 going paragraph A.

Fig. 9 shows a'preferred modification of the switch H in Fig. 6.

Fig. 10 shows the dial of the sending device of the present invention. This dial is generally like the dial disclosed in Figs. 7 and 8 of my said pending application Ser. No. 218,605, filed Sept. 10, 1927. However, the dial of the present invention has an added finger held Y for sending a series of twelve open impulses. V

Fig. 11 isa diagram showing the assembly of the seven sheets of accompanying drawings-to disclose the circuits employed to e emplify the present invention. The lines extending towards the margins which register are cent-inuations of the same line.

Equipment The telephone A in Fig. 1 is the well known common battery series type, but is equipped with an automatic calling device and dial as disclosed in Fig. 10. This dial, responsive to operating it in accordance with one of the two finger-hold depressions Z or Y will send a series of eleven or a series of twelve open impulses, respectively, depending upon which finger-hold is operated.

The line switch B is of the well known rotary class as described on page '53 of Hersheys Automatic Telephone Practice, third edition. However, the line switch B has an added wiper for the objects of the present inventlon. I

The connector D in Fig. 1 is of the well known type as shown in Fig. 7 3 of the fourth edition of the said book.

The first selector E in Fig. 2 is of the well known type sometimes called a Powell se-. lector, and described on pages 59 to 61 of the said third edition of Hersheys book.

However, two sets of off-normal springs, which respectively operate on in positions on the eleventh and twelfth'bank levels,an'd connected circuits, have been introduced for the purposes of the present invention. It also has twelve levels'of bank terminals.

The first selector G in Fig. 4 is of the well known said Powell type.

The selectors B C D E F and J in Fig. 2 and D in Fig. 4 are like selector G in Fig. 4.

The line switch L in Fig. 2 is like switch B in Fig. 1.

The connectors H and G in Fig. 2 are like connector D in Fig. 1.

The line finder switch F in Fig. 3 is of the class shown and described on pages 55 to 57 of the third edition of Hersheys book. How- 7 ever, it is modified for the purposes of the present invention.

The switch elements R and S in Fig. 5, and the switch elements H, I and J in Fig. 6, and the switch elements K, L and M in Fig. 7, belong to the class of switch 13 in Fig. 1, modified in accordance with the present invention.

It will be understood that any other suitable switches may be substituted for the said well known switches mentioned, without departing from the spirit of the present invention. Also, that the switches specific to the present invention may be modified by those skilled in the art without departing from the spirit of the present invention, as defined by the subjoined claims.

It will, of course, be understood that in a commercial embodiment of the present invention a plurality of switches in a group will be employed in place of the exemplary single switches used in disclosing the present invention, so that a plurality of calls may be co-existent, the switches in the groups having predetermined order. of use with respect to antecedent co-operative switches.

Detailed 0pemli0nnitatlng a call from telephone A to telephone A D and F and connector H The connection may then be released in the well known manner, responsive to the calling party replacing his receiver on the switch-hook. A call to telephone A the telephone number of which is 14321, will be effected in a generally like manner. It will be noted that the telephones A andA are both located tributary to the 1 olfice of the exchange, reached through the 1 level of first selector E. Of

course, other telephones of the system (not indicated) may be reached through other levels of the selector E, and, therefore, belong to corresponding oflices of the exchange. Thus, outgoing calls from telephone A under normal conditions are made in the well known manner, and employ well known switches,

with due regard to the special modifications Setting the'line leading to telephone A so that calls directed to said line will be forwarded to telephone A Let it be assumed that the party at telephone A desires to set his line so that calls directed thereto will be forwarded to telephone A. The party at telephone A will remove his receiver as if to initiate an ordinary call. This will cause the line switch to operate and select a firstfselector as E. The party at telephone A will then operate his callingdevice dial, Fig. 10, in accordance with the special finger-hold depression Z to effect a series of eleven open impulses which will step the shaft of selector E-vertically in accordance therewith and operate the eleventh vertical off-normal springs 201. The latter operation will cause the indicated plus battery to be applied over conductor 202,

bank terminal 12 of set 12 to 15, wiper 16 of set 16 to 19, armature 20, winding of polarized relay 21 to ground, the armature 22 applying ground through armature 23 to the winding of relay 24, the latter said relay actuating. The relay 24 will thus remain actuated as long as the ground is maintained by armature 22.

At the time the off-normal springs 201 operated, the selector E operated in the well known manner to rotate-in and seize by its wipers 205 to 207 the first set of idle bank terminals 208 to 210 on the eleventh level. The latter said set will be the ones corresponding to slow-releasing relay 212. The latter said relay will operate responsive to the seizing by selector E when its relay 213 actuates, and ground from armature 214 will be applied through bankterminal 208, wiper 205, armature 215, release trunk conductor 216, bank terminal 13, wiper 17, armature 26, conductor 27. This ground to the release trunk will, therefore, maintain the relays 213 and 28 actuated as long as the windings of relay 212 are maintained energized through telephone A by the party thereat maintaining his receiver off the switch-hook. The plus battery from springs 201 is similarly maintained to the winding of relay21 until the shaft of selector E is restored under control of the party at telephoneA.

At the time relay 24 actuates, its armature 30 disconnects the winding of relay 31. Armature 25 at the same time applies ground received from armature 22 to the winding of magnet 34 of the set relay 0. The latter said magnet will cause the springs of relay C to be operated and the dog 35 latched over the catch 36 to retain the springs of relay G operated after the winding of magnet 34 has been deenergized.

When the party at telephone A now hangs up his receiver, the relay 212 will deenergize and remove the ground from the release trunk 216, and thus cause the shaft of selector E to be restored and the armature 22 to assume the drawn normal position, free of its co-operating contacts so that the relay 24 -will'thereunon unlock the rela C hein in Unsette'ng the line leading to telephone A so that calls thereafter directed to said line will not be forwarded therefrom, the said line then being in normal condition Let it be assumed that the party at telephone A desires to unset his line, by unlocking the relay C and thus causing the springs thereof to restore to normal condition. The

party at telephone A will remove his receiver as if to initiate an ordinary call, having in mind that even if the springs on relay C are operated and locked by the dog 85, outgoing calls from telephone A through the line switch B will be effected normally as if the springs on relay C were not in their operated condition.

The party at telephone A will then operate his calling device dial in accordance with the special finger-hold Y depression to effect a series of twelve open impulses which will step the shaft of selector E vertically in accordance therewith and operate the twelfth vertical off-normal springs 217 v and select the relay 212, which relay is, for convenience, connected in multiple with the correspond ing vertically aligning sets of the eleventh and twelfth levels. Thus, the relay 212 was selected on the twelfth level in the same manner as it was selected on the eleventh level when the relay C was set. In the present instance current from the indicated minus battery is applied through the spring set 217,

conductor 202 to operate relay 21 in the indicated minus direction, the armature 22 applying ground through armature to the winding of relay 31, the latter said relay actuating: This latter energizing circuit will endure until the relay 21 1s deenergized by releasing the shaft on selector E.

At the time therelay 31--actuates,its armature 23 disconnects the winding of relay 24. V

Armature 40 at the same time applies ground from armature 22 to the winding of unlatching magnet 43 of the set relay C. This will on relay C to restore to normal condition.

When the party at telephone A now hangs 7 up his receiver the relay 212 willdeenerg'ize and remove the ground from the release trunk 216, and thus cause the shaft of selector E to be restored and the armature 22 to assume the drawn normal position, free of its co-operating contacts so that the relay 31 will thereupon deenergize, the circuits being now at normal;

Relay 0 2'8 locked and unlocked according to prearranged time schedule The time controlled circuit grounding device P and Q revolve continuously in the indicated direction at uniform speed, making a revolution in twenty-four hours. The conductive segment '46 applies ground received from brush 47 through brush'48, armature 49 to the winding of slow-releasing relay 50, the latter said relay actuating at 5 p.- In.

This is assuming that the drawn position of r the device Q, is at 12 p. m. The conductive segment 52 applies ground received from brush 53 through brush 54,- armature 55-to the winding of sloW-releasingrelay 56, the

latter said relay actuatingat 9' p. Ii'l': This is assuming that the drawn position of th device P is at 12 m. In view of the indicateddirection of revolution of the devicesP and Q, the device Q will be the first one to applygroi'ind through its brush48. j This will occur at 9 a. m.,as stated. Responsive to relay 5O actuating, relay 60 will actuate and lockto ground on armature 49 until the ground applied through brush 48 is removedbecauseof the segment 46 moving from under the brush 48.

When relay 6O actuates, it deenergizesthe relay 50, and the latter said relay will'the'n deactuate consistent with its slow-releasing characteristic. Only during the shorttime that relay 50 is actuated, ground from armature 61 will be applied through armature 23 to the winding of relay 24. The relay 24 will actuate in the manner before described to in turn cause the energization of magnet 34" from the ground appliedfrom armature 61 through armatures 23 and 25, to operate and lock the springs on set relay C.v

At 9 a. nil following the operation of relay 50, ground will be applied from brush 54 of device P'effective to operat'ethe relay 56.

Responsive to relay 56 actuating, relay 63- latter said relay will then'rdeactuate consistent with its slow-releasingcharacteristic. Onlyduring the; short time that relay '56 is actuated, groundfrom armature64 will be 7 applied through armature 30 to the winding The relay 31 will actuate in the of relay 31. V v manner before described to in'turn causethe.

energization of. the magnet 43 from the ground applied from armature 64 through armatures 30 and 40, to disengage the dog 35 sothat the springs of relay C will restore to normal condition, and, therefore, the relay C. will be in its unset condition.

It will be particularly noted that if, for example, the relay C was in its set condition at the time relay 50 actuated, the relay 24 will be caused to actuate as before described to energize the winding of the magnet 34, but to no efiective purpose with respect to the set condition of relay C. In the same manner, if the relay C is at normal and the relay 56 actuated, the relay 31'willbe caused to actuate as before described to energize the winding of magnet 43, but to no effective purpose with respect to the unset condition of relay C. 1 It will thus be clear that while applying plus or minus battery over conductor 202 will change the operative condition of relay C, the relays 50 and 56 can onlyset the relay C or unset it, respectively. Thus, if the party at telephone A has set the relay G at 4:45 p. m., and at 5 p. m.the relay 50 operates, no confusion can occur. In the same manner, if the party at telephone A has unsetthe relay C at 8: 30 a. m. and at 9 a. 1n. the relay 63 operates, no confusion can occur. However, in the event the subscriber through ,inadvertance fails to operate his set relay 0 before leaving for the night, the relay C will be automatically setat 5 p. m. V

In this connection it will be understood that there will be as many setscorresponding to P and Q, and their individualxpair of re lays 56 and 63, and 50 and 60, respectively, as there are times of the day when set relays, as C, are to be operated, the various set relays being associated with the proper said device as P and Q depending upon the time of day it is to be automatically set and unset. I

It willvbe noted that no confusion can arise by reason of more than one setting or unsetting operation occuring. That is, by a second partyperforming a setting or unseting operation. a If two or more like operations are madesuccessively, only the first one will be operatively efiective to the set relay-C.

Call to the line leading to telephone A under normal eonditionhuherein the relay is not set Assume that the party at telephone A debe operated in accordance with digits 2.2- 21 1 after initiatingthecall, This will successively operate the selectors B C and.

J and connector D so that wipers 65, 66, and

v 67 will seize bank terminals 71, 72, and 73, re-' spectively. be applied overprivate wiper 65, bank ter- Ground from the connector will minal 71, spring 74 to the winding of relay at telephone A, in the Well known manner, the effective circuits being those well known from Hersheys book cited.

The connector D will now apply signaling current effective to the bell Call to the line leading to telephone A Wk,

der the condition that the set relay 0 is in operated condition Now assume that at the time the wipers 65 to 67 are set upon the bank terminals 71 to 73, respectively, the set relay C is in its operated and latched condition. Under the latter said condition, the relay 28 will not be energized, since the normal conductors are disconnected fromrthe line leading to telephone A. However, the latter said condition does not prevent the party at telephone A normally extending calls from said telephone.

.It will be noted that the conductors leadin g from bank terminals 71 to 73 disconnected from the line leading to telephone A are now connected to conductors 75 to 77, respectively. Thus, when the connector D seizes the line terminals 71 to 73, groundis applied from the connector over wiper 65, bank terminal 71, spring 74, conductor 75, armature 301,

' lower winding of relay 302, winding of common relay 303 to grounded battery, the relay 302 actuating and causing the dependent common relay 305 to actuate. Armature 306 on relay 302 will attract from'its resting contact to its make contact, while armature 301 remains inert for the time being. This condition causes all the bank terminals accessible from the wiper 311, of the group 311 to 313, to be grounded by the armature 314 of relay 305, excepting the bank terminal 315, corresponding to the relay 302, due to the attracted condition of armature 306. Ground is applied from the armature 314, conductor 317,

armature 318 to the winding of sl0w-releasing relay 319, the latter said relay actuating.

The armature 321 applies ground to the lower terminal of the winding of relay 323, while the ground on-the bank terminals successively engaged by wiper 311 is applied through armatures 324 and 325 to the-upper terminal of thewinding of relay 323. The lat ter said ground is also applied through the interrupter armature of motormagnet 327 to the winding thereof, the said motor magnet operating to' successively step advance the wipers 311 to 313.. When Wiper311 encounters bank terminal 315 it will notv receive 3 ground because of the attracted condition of armature 306; so that the-short-circuit is re moved from the winding of relay 323 and the direct ground is removed from the winding of the motor magnet 327. Due to the marginal adjustment of the motor magnet, it will cease operating under the condition, but the The ground received over conductor lay 407.

V the latter said relay 302 at armature 301 and connects ground received from the connector D over conductor 75 through armature 301, bank terminal 315, wiper 311 to armature 324 to maintain the relay 323 locked before the armature 321 has had time to retract. Th relays 303 and 305 will now deactuate it there is no other relay like relay 302- with its/lower winding energized, due to a waiting call. It the relays 303 to 305are actuator after relay 302 tully actuates, the ground applied over conductor 317 will be continued through armatures 318 and 330 to the armature corresponding to 318 of the next finder switch like F (not shown) of the group of whichswitch F is' one.

i to the winding of relay 335, the latter said relay actuating. Resultant to the actuation of the relay 335a circuit path can be traced "from grounded battery, upper winding ot'relay 401, armature 402, conductor 403, armature 336, conductor 337, armatures 501 and 502 in multiple, conductor 503, armature 338, conductor 339, armature 405, lower winding of relay 401 to ground, the latter said relay actuating, followed by slow-releasing release re- Ground will now be applied through armature 408 to release trunk concuctor 409. Ground is applied through armature 341, conductor 342 to' the winding of relay 505, the latter said relay actuating. Ground will now be applied from armature 506, wiper 509 of set- 507 to 509, bank terminal 510, bank terminal 511, wiper512 of set 512 to 515, bank terminal 516, armature 517 to the winding of relay 518, the latter said relay actuating and applied through armatures 331 and 334 locking through armatures 519 and 520 to ground In this connection, it will be noted that the interrupter l revolves at the rate. of approximately twelve times per second, so that the next ground impulse applied thereby will be to the windin of rela 523 and throu h ar- 2 b y b that the latter said wipers are now. resting appliedthrough armature 521, armature. 522

mature 524 to the winding of motor magnet 525 or" switch R, the said relay 523 and magnet 525 coincidently operating. The wipers 512 to 515w1ll thus 3e step advanced responsive to the groundings of the interrupter T The armature 501 will attract coincident with the first energization of the motor magnet, the armature 502 of relay 526 will maintain the relay 401 in selector G energized until the wiper 514 encounters groundon the first oil normal'bank terminal co-operative therewith,

"and, thereby, energizes relay 526 over an obtowa vious circuit path, after which time the relay 401 in selector G will be under the sole control of armature 501.

At the time armature 331 attracted, it applied ground to energize the magnet M. The latter said magnet will draw the portion of the shaft carrying all the wipers excepting private wiper 315 so that, enough pressure on tion 803 tits slidably in the sleeve 801 and car-v rise a fixed pin 804 which may move along the slot 805. Thus the wipers on the portion of the shaft 803 rest lightly on the'bank terminals as they are rotated by the shaft section with which the motor magnet 327V 00- operates. Then when the magnetM is enerthe section of the shatt803 will be drawn rds the magnet M and the pin 804- will change itsposition accordingly, while all the w"; ers on the section 803 will rotate with section 802 wherein the pin 804 is a link between said sections 802 and 803. The shaft is journaled in bearings 806. Y

Bank terminals 510, 527 to 530 of switch S are respectively tied by conductors to wipers to 347 on the shaft 803 oi the switch F.

t will also be noted thatthe latter said wipers are now resting upon bank terminals 351. to which align with bank terminal 315; That is to say, the bank terminals 351 to 355 of switch F are individual to the line leading to telephone A.

The said bank terminals 351 to 355 are respectively tied by conductorsto wiper 601' of set 601 to 603 of switch l-l; wiper 604 ot'set 604 to 606 of switch I wiper 607 of set 607 to 609 of switch J wiper 701 of set 701to 703 of switch K; wiper 704 of set 704 to 706 of switch L. i

Bank terminals 531 to 540 are respectively tied by conductors to wipers 356 to 365 on the shatt 803 or" switch F. It will also be noted upon bank terminals 366 to 375 which align with bank terminal 315' That is to say, the bank terminals'366 to 375 are individual to theline leading to telephone A.

Conductors 707 to 716 in Fig. 7 respectively lead to bank terminals 366t0'375, in Fig, 3. Thus, conductors 707 to 71 3, in the present assumed position or" the wipers on the shaft of switch Fare respectively conductively connected with bank terminals 531 to 540 of switch R. That is to say, conductors 7 O7 to 716 respectively correspond to bank terminals -of switch R which determine the digits 1 to 0. In the same manner, the numerical order bank terminals 510, 527 to 530 of switch S respectively corresponding to wipers 601, 604, 607, 701 and 704 of switches H to L.

It will appear presently that the call in the present instance is to be forwarded to telephone A, the number of which is 13431, and accordingly, jumpers 610 to 614 in Fig. 6 are run between the cross connecting terminals X to predetermine that the sending mechanism in Fig. 5 will normally send a corresponding train of directive digit lmpulse serles. Thus,

' circuits can now be traced as follows: Bank set 619 to 621, jumper 611, conductor 709,

bani: terminal 368 of switch F wiper 358 to bank terminal 533 of switch R; bank terminal 528 of switch S, wiper 345 of switch F, bank terminal 353, wiper 607 of switch J, bank terminal 622 of set 622 to 624 jumper 612, conductor 710, bank terminal 369 of switch F, wiper 359 to bank terminal 534 of switch R; bank terminal 529 of switch S, wiper 346 of switch F, bank terminal 354, wiper 701 of switch K, bank terminal 717 of set 717 to 719, jumper 613, conductor 709, bank terminal 368 of switch F, wiper 358 to bank terminal 533 of switch R; bank terminal 530 of switch S, wiper 347 of switch F, bank terminal 355, wiper 704 of switch L, bank terminal 720 of set 7 20 to 722, jumper 614, conductor 707, bank terminal 366 of switch F, wiper 356 to bank terminal 531 of switch R. That is to say, bank terminals 510, 527, 528,529 and 530 of switch S are, by reason of the position assumed by the wipers of switch F in seizing-the terminals corresponding to the line leading to telephone A, connected respectively to bank terminals 531, 533, 534, 533 and 5310f switch B, remembering in this connection, that armature 506 is applying ground through wiper 509 to bank terminal 510. V

Going back to the condition wherein the relay 526 actuated responsive to the 'wiper ice rupter 1 until the relay 541 is caused to actu- I ate. This occurs responsive to the ground 514 encountering the first grounded bank terminal, it will be clear that when the relay 526 actuates, the relay 523 by its armature 501 efliects the open impulses for directing the extension of the connection to the line leading to telephone A. The latter said relay will continue to operate its armature 501 responsive to the ground impulses from the interapplied from wiper 509 present on bank ter- .n1inal 531 being encountered by,wiper512,and

conducted over wiper 513 and engaged bank terminal to the winding of said relay 541. The relay 541 locks'through its armature 542, wiper 514 to the ground on its engaged bank terminal. And, in view of the fact that all the bank terminals co-operative with wiper 514, excepting the one it is shown resting upon, are permanently grounded, the relay 541 will be maintained locked until the wiper 514 is returned to the drawn position. The relay 523 will have energized onetime, to efi'ect the impulse for the first digit 1, after relay 526 actuated until wiper 511 encountered bank terminal 531 and thereby caused relay 541 to actuate and disconnect the winding of relay 526 to retract armature 502, so that armature 501 therefore efiected one open impulse to the relay 401 for causing the-selector G to select an idle trunk on its first bank level leading to second selector D ,-in the well known manner. v

r The ground derivedthrough wiper 514 is new applied through armature 543 to the interrupter contact on the motor magnet 525, thelatter said magnet thereupon operating to restore the wipers of switch R to the drawn normal position, the relay 541 deactuating consistent with its slow-releasing characteristic, the latter being timed to insure suiiicient trunk hunting time for the switches operated; the selector G in the present instance.

At the time relay 541 actuated, ground applied through armature 545 energized motor magnet 546, preparatory to causing-the wipers of switch S to advance one step responsive to the retraction of the armature 545, at which time ground applied through armature 509 will be extended to bank terminal 533. Relay 541 being deactuated,the paths from the interrupter I to the relay 523 and motor magnet 525 are closed for the initiation of the seconddigit series of two open impulses corresponding to the digit 3, which said series will terminate when the wiper 512 encounters the latter said bank terminal 533, in the manner as described when the single impulse for the first digit 1 was sent. The relay 541 will operate to efi'ect the said termination of the second digit series and provide the space between the second and third digit series and cause the wipers or the switch S to be advanced one step preparatory to sending the third digit series of four open impulses. The second selector D operated in the well known manner to select the first idle trunk leading to third selecter F responsive to the second digit series.

Ground applied through wiper 509 is now extended to bank terminal 534. The switch 0 idle trunk leading to connector H The wipers of switch S-are thereafter caused to advance one step preparatory to sending the fourth digit series ofthree open impulses, the wiper 509 then resting upon bank terminal 529, so that ground will now exist on bank terminal 533 of switch R.

The wipers of switch It will new step. ad Vance while. the: fourth digit series corresponding to: 3 will be sent to operate connector H vertically in the well known manner. Thev switch will thereupon restore-its wipers to the. drawn position and the wipers of the switch S will be advanced one step so that Wiper 509. will bezresting on bank terminal 530 and ground till then exist on bank. terminal 531,. preparatory to the sending of the lastsingle open impulse. corresponding to digit.l.

The wipers'oi switch R will now step advance while the fifthdigit impulse. is being sent effective to rotating the wipers of connector H in the well known manner to seize and ring upon the line leading totelephone A7, in the well. known manner, after which 7 the wipers of the: switch R will restore. to the drawin position andrelay 5.41 willdeactuate.

At the'time relay 541 deactuates. following the sending: of the open impulse constituting the last digit 1 the wipers. or switch S will be advanced one. step in the manner as before, this time. the ground on bank terminal 550 beingjapplied over wiper. 508, conductor 551, make-before-break spring 378 to the winding of relay 379, the latter said relay actuating and locking to toe grounded armature 33%, the relay deactuating. This will cause relays 505 and 518. to deactuate.

- At this time, the line. relay in. the connector H is energized through a path involving arm'atures380 and381. and the winding of polarized relay 382,.in place of the armatures 50l.and 502'. The relay 382 will tilt its armature clockwise. into the. indicated Ring. p0s., however, to. no operative eflect.

It. will be notedat this time, that when the relay 323 first actuated, the. windings of the backebridge relay in connector D thereby became connected through bank terminals 383-384, wiper 312313, armatures 385 386, make-before-break springs 387-388 and the upper and lower windings of relay 389 to battery and ground, respectively. The backbri'dge relay in connector D and relay 389 will not actuate under the condition, because the battery on the upper winding of said backbridge. relay and the battery on the upper winding'of relay 389 oppose.

Upon the response at telephone A, wherein the connector H will cause the direction of current traversing the winding of relay 382 to be reversed 'in direction so that the armature of the latter-said relay will be tilted: counterclockwise in the indicated Ans; po's, under which" condition ground from the. armature of relay 382 will energize the relay 390, causing obvious circuit changes which. will cause: the: battery on: the. upper winding of the back+bridge relay in connector D to. energize in. series with the lower winding of relay 389. inswitch- F, said back-bridge.

relay and relay 389 actuating. The actuation of. the backbridge' relay in connector D-wlll cause. current. to be. reversed to the calling telephone A. The talking path between the telephoneA an'd A. will include the condensers 391-392;-

It will. be. understoodthat. any well known or. other. suitable so-terined repeater may be introducedzinto the trunk leading-in to selector'i) from thebanksof selector G; This will. also apply to the trunk leading-in to selector D fronithebanks ofselector E. The efiective operation. will be the same as if the said repeaters were not employed, being used for translating from three wires to two wires for the inter-otlice trunk.

UaZZing party attelephonerl abandons call while call is being forwarded If it is assumed that the calling party at telephone A abandons the callwhile-thecall is being forwarded from the primarily called line to telephone A, it will be clear that the connector D and antecedent switcheswill restore to normal, subject to new use. This will remove the ground from conductor 7 5, so that relays 323. and 3.35 of switch. F will deactuatetorender said F subject to new use. Relay 505 will deenergize responsive to the deactuationl ofv relay 335, so that relay 518' will unlock. Thearmature-560 onrelay 518 will now apply groundthrough wiper 507 to cause. the. motor. magnet 5.46 to restore the wipers of. switch S to the drawn normal position. The armature'561. on relay 518 will now-apply ground through wiper'515 to cause the motor magnet 525 to restore the wipers of switch R to the drawn position.

Encountering the: line. leading. to telephone A. busy Had the line leading to telephone A been encountered busy, the connector H would have applied busy tone back over the lower talking conductor339 condenser 392, audible to the. calling party at telephone A.

Releasing connection-called party. hangs up first nector D will not release its wipers underthe' present condition. Also, the connector H Wlll not release its wipers under the present condition because the line relay of the latter said connector is still maintained energized through the winding of the relay 382.

When the calling party at telephone A now hangs up his receiver, and in .view of the fact that the backbridge relay in connector D is deactuated, the connector D will release its wipers, and the connection from telephone A up to and including the connector D will be released to normal, subject to new. use. Ground being thus removed. from-conductor 75, relay 379 will deactuate and open the path including the windingxof relay 382, so that the front-bridge relayin the connector H will deactuate and'cause the latter said connector to release its wipers and the antecedent selectors F J D and G,the circuits used in the call now being at normal.

Releasing connectioncalling party hangs up first 7 If it is assumed that the calling party at telephone A hangs up first upon the termination of the service this will cause the line relay of connector D to deactuate, followed by the release of the antecedent switches J C B and L the connector D remaining in seizure. When the called party at telephone A hangs up, the current traversing the winding of relay 382 will be reversed, causing the relay 390 to deactuate to deenergize the backbridgerelay in connector D so that the latter said relay will cleactuate to release the wipers of the latter said connector. Then the connector D releases,ground is removed from conductor 75, so that relays 323 and 379 will deactuate to open the circuit path including the winding of relay 382 and cause the line relay in the connector H to deactuate. Since the back-bridge relay in this connector H deactuated responsive to the party at telephone A hanging up, the wipers of connector H will release, the circuits used in the call being now norma Party at telephone Am-ag change the normal prearranged setting for fan warding call to telephone A to a random desired Zine 701 and 7 04 of switches I, J, K, and L, respectively.

Before the party at telephone A hung up his receiver after causing the set relay C to be actuated and locked, the said party could have changed the setting from that to cause calls to be forwarded to telephone A as has been described. V

' Let it be assumed that it is his desire to have calls directed to his line leading to telephone A forwarded to a random desired line A ,'the

telephone number of which is 14321.- The party at telephone A will operate his dial to annex the digits 1-1321, following the sending of the series of eleven open impulses to set the relayC.

It will be noted that under the condition of causing the relay C to be set as assumed, the relay 2will be in actuated condition while the party at telephone A maintains his receiver off the switch-hook, so that a circuit can be traced from line terminal 81, conductor 82, attracted armature 88, conductor 84-, upper winding of relay 725 to grounded bat. tery. Also, a circuit can be traced from terminal 85, conductor 86, attracted armature 87, conductor 88, lower winding of relay 725 to ground, the latter said relay actuating. The slow-releasing relay 726 actuates, energized in a local circuit of relay 725. Relay (2! then actuates, energized in a local circuit of relay 726. 7

When the party at telephone A hangs up his receiver after setting relay 0 forthwith without annexing any digits, the relay 725 will deactuate, its armature 728 applying ground through armature 729, winding of slow-releasing relay 7 30, wiper 7 of set 731 and 732, bank terminal 788, conductor 7 3th to the winding of motor magnet 625, the latter said magnet stepping the wipers of switch H one step from the drawn position. Relays 726 and 727 will deactuate consistent with the slow-releasing characteristic of relay 726.

It will be noted that wiper 705 normally grounds conductor 735 and, therefore, similarly grounds wipers 702, 608, 605 and 602. So when the wiper 602 moved-to bank terminal 628, this ground is continued over conductor 629, armature 7 37 conductor 738 to all bank terminals engaged by wiper 603 at offnormal positions. The magnet 625 will operate by interrupter action, so tiat no upset will occur to the setting relay 0 to unset the line. It will also be noted that when relay 730 actuated, its armature 7&0 applied ground to the winding of motor magnet 7 41 of switch M so that when relay 7 3O deactuates following the impulse sent to the motor magnet 625, the armature of the ,inotor magnet 7 41 will advance the wipers of switch'M one step- When the relay. 727 deactuates, ground will be applied through armature 743, bank terminals co-operative with wiper 731, interrupter armature of motor magnet 741 to the windin of the latter said motor magnet, causing it to operate and step the wipers of switch Mv around to the drawn position. i

However, in the present assumed instance, the party at telephone A does not hang up his receiver forthwith after setting the relay C, but on the other hand, annexes the five digits 14-321 designating the random telephone A for example. The sending of the digitl constituted of one open impulse will cause the relay 7 25150 momentarily retract armature 728, so that a ground impulse will be sent from said armature 728, armature 729, winding of relay 730, wiper 732, bank terminal 733, conductor 734 to the winding of motor magnet 625, the wipers of switchH being stepped one step so wiper 601 will rest on bank terminal 630 when the armature of said motor magnet 625 retracts. The armature 740, when retracting, will cause the op eration of the motor magnet 741 to advance the wipers of switch M one step, so that wiper 731 will then rest on the bank terminal 745.

The sending of second digit 4 constituted of tour open impulses will cause the relay 725 to momentarily retract its armature 728 four times, so that four ground impulses will be sent from the armature 727, armature 729,

winding of relay 730, wiper 732, bank terminal 745, conductor 746 to the winding of motor magnet 635, the wipers of switch I being thereby stepped four steps so that wiper 604 will rest on bank terminal 636. The retractionof armature 740will causethe operation of the motor magnet 741 to advance the wipers of switch M one step, so wiper 732 will rest on bank terminal 747.

The sending of third digit 3 constituted of three open impulses will cause the relay 725 to momentarily retract its armature 728 three times, so that three ground impulses will be sent from the armature-728, armature 729, winding of relay 730, wiper 732, bank terminal 747, conductor 748 tothe winding of motor magnet 645, the wipers of switch J being thereby stepped three steps so that wiper 607 will rest on bank terminal 646. The retraction of armature 740 will cause the operation of the motor magnet 645 to advance the wipers of switch M one step so that wiper 732 will rest on bank terminal 750.

The sending of fourth digit 2 constituted oitwo open impulses will cause the relay 725 to momentarily retract its armature 728 two times, so that two ground impulses will be sent from armature 728, armature 729, winding of relay 7 30, wiper 7 32, bank terminal 750, conductor 751 to the winding of motor magnet 55, the wipers of switch K being thereby stepped two steps so that wiper 701 will rest on bank terminal 756. The retraction of ar mature 740 will cause the operation of the motor magnet 741 to advance the wipers of switch M one step so wiper 732 will rest in bank terminal 757.

- The sending of the fifth digit 1 constituted of one open impulse will cause the relay 725 to momentarily retract its armature 728 one time so that one ground impulse will be sent from armature 728, armature 7 29, windof relay 730, wiper 7 32, bank terminal 757, conductor 758 to the winding of motor magnet 765, the wipers of switch L bein thereby stepped one step. so wiper 704 will rest on bank terminal 766'; The retraction on armature 740 will cause; the: operation: 01% the motor magnet 741 to advance the wipers of switch. M one step, so wiper7-32 Willi rest onbank. terminal; 7.67. v

I twill: be noted! that under the lastv toregoing conditionthe bank. terminals 510, 527, 528, 529' and 530 cooperative with wiper 509' are now connectedthrough wipers 601, 604, 607 7 01 and 704 over obvious,circuitpathszto terniir is 531, 534 533,532, and 531,respectively. Under thiscondition, it. will be. clear in view of previous descriptions, that. the" sending, mechanism will be set to send the. train of. digits 1.-432.1 responsive. to the germinals 7110.73 being seized by connector In this connection, it will. be understood that although thejumpers. 6l1to 6I4set the sending mechanism to send the digits. 13 4--31 corresponding. to: the.- telephone. number of telephoneA,when the. wipers-601,604,, 607,. 701, and. 7 0.4. are. in their. drawnv normal. positions, this. sameset-up may be attained by directively setting the latter said wipers. on. the co-operative; bank positions corresponding to digits 134'-3-1,. respectively- That isto say, it is not necessary to have the. jumpers 611 to=614', butto do away with them will make it necessary to: always directiively set not only relay O.',.but also the. switcheslzl to L in accordance with. a telephone number.

Upon the party at telephone. A hanging up his receiver, relays 24, 725, 726 and 727 will deactuate; also, the relay 212, the windings of which have been in multiple with the wintc lings of relay 725. The wiper 705 being off the bank terminal 721 it is drawn resting on and is resting on bank terminal 770', when relay 727 deactuates there will be no ground applied through the armatures of this relay from wiper 705, so the wipers of the switches. H toL will not be restored at this-time. However, when armature 743 retracts, it causes the wipers of switch M to restore. to the drawn position by interrupter action of its motor magnet 7 41'.

It will appear presently that responsive to. relay 725 deactuating;,relay 93 will actuate and cause the lower winding of relay 302 to energize. This operation is only momentary and will not upset the intended operation. Ordinarily, the party setting relay C and the switches H to L will not hang up hisreceiver: at this time, but: will operate the dial, as will appear presently, to cause a test to be made of the setting by causing the impulse sending device to send impulses corresponding to the setting tooperate the switches to extend a connection from-the calling line to the called line-corresponding to the setting; He will then hang up his receiver; Of'course, moving bank terminal 767 onestep to the lett, making it necessaryto anneXLtwo digit series:

1; only part of'switehes H to L are set they will restore Inthis connection, it will be notedthat if r the party at telephone A, when setting the relay C.

switches H to L had failed to set all of the latter said switches, by leaving off one or more of the five digits, the wiper 705 would then be in the drawn position. So when the relay 7'27 deactuates responsive to the hanging up of the receiver of telephone A, this ground on wiper 705 would be applied through bank terminal 721 and through those of the wipers 602, 605, 608 and 702 as are in ofl'-normal position in multiple, to conductor 629, and through the multipled armatures on said relay 727 to the resting contacts cooperative with the armatures on the motor magnets of the switches H to K which are offnormal, to restore these switches to the drawn positions, the switch M restoring in the manner before described fromarmature 743. Under this condition any calls directed to the line leading to telephone A will be forwarded to telephone A in accordance with the settings of the'switches H to L when in the drawn positions, since only relay C will-be set.

U nsetting the relay 0' and the switches H to L When the party at telephone A desires to unset his line for forwarding calls directed thereto, he will remove his receiver as if to initiate a call, and thereupon operate his calling device oial in accordance with the fingerhold Y used in sending a series of twelve open impulses. This willcause the relay 31 to operate in the manner before described to unlatch the catch 36 to release the springs of armatures on relay 727, through the interrupter contacts of the motor magnets of switches H to L to restore said switches to the drawn positions, thus efi'acingthe spe-- cially set up condition of the switches H to L.

The switches H to L (with the exception of switch H, which has a twelfth bank terminal, as will appear presently) are each drawn with five sets of bank terminals. In a commercial embodimentthere would-be eleven such sets; a normal position set and one position for each digit from 1 to 0.

The five switches H to L contemplate a train of five digit series. It will be clear that more switches may be added to increase this range, the switch M having corresponding bank positions. added.

Ground will now be applied through spring 90, conductor 91, multipled Party at telephone A after causing relay 0 to be set may hang up his receiver and initiate a new calll and by his dial direct the call to the nnmberof his own line The'connector D (or any other connector of the group containing connector D) and switch F will operate in the manner described from telephone A to cause the call to be extended to the telephone predetermined by the said setting of relay C; The same will apply if the switches, H to L are set for eX- tending calls to a randomdesired line. The foregoing has in View that the line leading to telephone A is clear of the bank terminals accessible from connector D when the set relay C is in the set condition.

Party at telephone A after causing relay 0 andthe switches H to L to he set may thereupon cause the call to be extended to the random desired line If the party at telephone A desires to verify the set condition after causing the relay C and the switches H to L to be set for forwarding calls to a random telephone A he may, without first hanging up his receiver, operate his dial in accordance with the finger-hold Z and thereby send a series of eleven open impulses to cause the call to be extended to the line indexed by the set condition of the switches H to L, which in the present assumed instance is to telephone A The relay 24 underthe present assumed condition, is still actuated and energized from armature 22. Thus, the relay 725 will momentarily retract its armature 728 eleven times and send a corresponding number of ground impulses through armature 729, winding of relay 730, wiper 732, bank terminal 7 67 (it having stepped to the latter said terminal following the setting of the switch L), conductor 771 to the winding of relay 93, the latter said relay actuating and locking to release trunk conductor 27 responsive to the first impulse of said series.

Armature 9d closes the grounded Winding of relay 95 to conductor 75, so that the lower winding of relay 302 will energize in series with the winding of relay 95. Slowreleasing relay 96 will be operatively energized in a local circuit of relay 95. Relay 302 will operatively attract only its armature 306 from its resting contact to its make contact in the manneras when connector D ap: plied ground over conductor 75. The finder switch F or one of its group will operate to hunt for and seize the bank terminals correspondingto the line leading to telephone A. When this latter line is found and relay'323 actuates, ground from armature 321 is applied through wiper 311 to conductor 75 as before described. This latter ground will deconductors 202 and 2?.

look.

. when energize the winding ofrelay '95 and it Will therefore deactuate, followed by relay 96.

After relay v95 ,deactuates and'until relay 96 deactuates, ground is applied through armatures 97 and 98 to thewinding of relay 99, the latter said relay actuating and locking to conductor 75. iii-matures 101 and 102 disconnect the line conductors leading from the telephone A to the line switch B, so that relay-212 will eactuate to remove ground from Relay 93 will un- Responsive to relay 99 actuating, the windings of relay 389 will energize in series with telephone A, the receiver of which is ofi the switch-hook. The armature of relay 289 will apply ground to wiper 311 and conductor i to maintain the relay 99 locked.

Responsive to the actuation of relay 99 the relay 212 will deactuate to removethe ground from conductor 202 so that the relay 28 of the line switch B will deactuate and first selector E will restore to normal in the obvious manner. Relay 21 will deenergize and relay 24 will deactuate responsive to relay 28 deactuating.

It will be noted, in this connection, that when relay 2% is actuated, the private bank then resting upon the bank. terminal 315, it

will be clear that the relays 323 and 335 thereupon actuate 1n the manner before described. This latter operation will cause the impulse sending mechanism in Fig. 5 to transmit a train or digit series to progress the call to telephone i 2 in accordance with the settings of switches H to L in the manner as before described, he connector G applying ringing current to the line leading to telephone A Relay 335 deactuates and relay 3T9 actuates.

Current derived through the windings of the relay 389 traverses the telephone A in the same direction aswhen it derived current from the windings or relay 212. However, the party at telephone A removes iis receiver irom'the switch-hook in responding, the arn'iature of relay 382 will tilt into the indicated Ans. pos. and cause the relay 390 to actuate for reversing the direction of current applied through telephone A. This reversing of current direction is for operating supervisory devices, call meters and prepayment :coin collecting apparatus. .Moreover, the reversal .eliective to relay 382 may be caused by reversing apparatus located intermediate of switch F and connector G and operated message timing apparatus. The said supervisory devices, call meters and .prepayment coin collecting apparatus, and the said reversing apparatus has not been shown, since. such hasbeen disclosed in applications of applicant filed heretofore. Moreover, thisv reversing apparatus may be included in a well known Bunk impulse repeater "located intermediate of the switches F and The party at telephone A is now in talking relation with the patty at telephonefA At the time relay 99 actuated andlocked and selector E restored its wipers and "relay 24 deactuated, relays '725, 7216 and '727 deactuated, causing switch 'M to be restored to the drawn position in the manner before described.

Release of COMBGtiOik-CCblld party hangs up first If it is assumed that thecalled party at telephoneoA hangs up first upon the termination of the conversation, this will reverse the direction of current traversing the winding of relay 382, causing the relay 390120 Ideactuate and restore the direction of current traversing the telephone A. The connector G will not release its wipers under the condition, since the windings of its line relay are still in series with the winding of relay 382. However, when the party at telephone A hangs .up :and deenergizes the relay 3-89, the relay 99 will be thereby unlocked, since ground will then be removed from conductor 75. This also causes irel'ays323 and 3.7 9 to deactuate. This restores .the condition of switch F .to normal and opens the energizing path for the hue relay of connector G so that theconnector-Gtand antecedent switches release to normal. However, relay (1 and switches H to L are in their set .positiomand this latter has been verified by ltheresponse of the ,party at telephone A Y Release of -00nne0ti0wcalling party hangs "up first If it .is assumed that the calling party at telephone A hangs up first upon "the termination ofthe conversation, this will deenergize the relay 389 so that relay 99 will unlock and remove the ground from conductor 7 5, causing relays"323,'379and390 to deactuate and open the energizing circuit for the line relay of connector G The switches antecedent to said connector will release, but

the said connector will remain in seizure. .vhen the party [at telephone A hangs up, connector G willrelease its wipers. However, relay C and switches H to L are in thei set position. I

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