US974866A - Automatic telephone system. - Google Patents

Description

y A. H. DYSUN"; AUTOMATIC TELEPHONE SYSTEM.

nruou'lon rmzn me. a, 1001. 974,866. Patented Nov. 8, 1910. a sums-sum 1.

w w \M N A. 11., Dyson; immune TELEPHONE SYSTEM.

LPPLIOATIO]! rum) ma s, 1901. Pa n Nov. 8, 10-

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A! El AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 8, 1907.

Patented Nov. 8,1910,

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'fromt e line grou UNITED STATES PATENT OFFICE.

ALI'BED H. DYBON, OF CHIGAGQ ILLINOI S, ASSIGNOB, BY MESNE ASSIGNMENTS, TO

KELLOGG SWITCHBOABD & SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented N 0V. 8, 1910.

Application filed August 8, 1907. Serial No. 386,977. 7

To all whom it may concern:

Be it known that I, Anrnnn H. DYSON, a citizen of the United States, residing in Chica county of Cook, and State of Illinois, ave invented certain new and useful Improvements in Automatic Telephone S stems, of which the following is a spec1fication. 4

My invention relates to automatic telephone systems in which a plurality of directively operated selective switches are emloyed in completin each connection, by linking together loca exchange with which the switches are associated. I

My invention has particularly to do with the means b which the selective switches of the class t operated,vordinarily called first selectors, are associated with the calling line's. v

In accordance with my invention, each subscribers line is rovided' at the exchange with passive called the banks of a number of connectors, and with passive calling terminals appearing in the banks" of a number of line selectors.

'Each line selector has preferably a firstselector individual to and linked with it, although I do not wish to be limited to this embodiment of my invention. The lines of an exchange, assuming, for instance, a ten-thousand line system, are referably divided both as calling'and called ines, in groups of one hundredfthe connec- .tors for makm connection with the called terminals of a me group as well as the line selectors for calling terminals of a line grou being pref erably provided in numbers etermined by the ex ted number of co-existing calls permanently sand line system, dred oups of one hundred lines each, each of w ,ich oups may have its calling terminals mu tiphed. to ten line selectors, maka total of one thousand such switches. As before indicated, the first selectors would be equal in number to the line selectors, making one thousandnand the' first selectors would have before their contact wipers multiple terminals, arranged in ten oups of ten contact sets each, of second sefia ctors asdifif'erent ousands of the exchange, in the wellknown manner, the sets of each group or ent one hundred line trunk circuits at the terminals," appearing in making connection with the- Thus in a ten-thow' ere would be one hun level being connected to second selectors for a difi'erent thousand. The second selectorswould have before their contact Wipers, ten groups or levels of multiple contact sets, each level comprising ten sets and being connected to connectors assigned to a difl'ergroup of subscribers of the thousand serves.

The connectors would have before their contact wipers multi le terminals of the lines of a one hundre line group arranged in ten groups or levels, aocordm .to the tens values of the numbers of the undred, the line terminals-in each level being arranged according to the units values of the line numbers, all in the well-known manner. Thus assuming a first selector connected with a calling line, the calling subscriber transmits directive impulses to said first elector to selectthe level of the thousand wanted, the first selector thereupon automatically picking out terminals of the first idle trunk leadin to a second selector of that thousand, wfiereafter the calling subscriber directively operates the second selector to g the hundred wanted whereupon the second selector automatically icks out terminals of the select'ed'levelleading to the first idle connector of the hundred wanted. The connector is directively operated both to select the group wanted and thereafter to pick out the particular line wanted, whereafter a busy signal will be transmitted to the calling subscriber-or the bell of the called subscriber rung in the usual manner, accordi to the idle or busy condition .of the calledfor line. In a ten-thousand line system there would be one thousand connectors, multiplied to one thousand second selectors, whichsecond selectors would be multiplied to theone thousand first selectors, in the usual manner.

In Fi ure 1, consisting of Parts 1, 2 and 3, I have lustrated one embodiment of my invention. Thesaid parts when placed in consecutive numerical order, illustrate a complete circuit dia am including the necessary connections or completing a conversational circuit between a callin subscriber C and a called paratus being shown in its position of rest, the talking circuit to be established being indicated by the heavily marked conductors,

which the second selector pick out a group of terminals of subscriber D, t e ap- 1 h of a line selector F. The multiple terminals the well-known Strowger selector and connector switch illustrated in patent to Keith, No. 815,321, dated March 13, 1906, and patent to Keith, No. 815,176, dated March 13, 1906, respectively; and in the following description it will be assumed that switches having such mechanical connections as those above indicated are used in connection with the circuit diagrams at line selector F, first selector G, second selector H, and connector L. Referring o saidFig. 1, I show at C a diagrammatically illustrated common battery subscribers telephone outfit comprising -the usual transmitter, receiver, condenser and call bell, the hook lever 1 being arranged on the removal of the receiver to disconnect the call bell andcomplete an operative bridge of line limbs P and S including the primary of the induction coil and the transmitter. The calling device 2' is for actuation by the subscriber to transmit directive impulses over the telephone line, and is to be rotated by hand in the direction indicnted by the arrow until as manyof its teeth have passed'below spring 3 as there are units in a digit to be transmitted. The device bein thereafter released, is turned b its associated spring in the reverse directron, each tooth as it passes over s ring 3 causing said spring to engage an disengage its associated contact, whereby limb P of the line will be grounded at E as many times as teeth are brought below spring 3. The last' tooth at the left of dial 2 is, on actuation thereof, brought above the spring As the dial reaches normal, the said tooth causes spring 4 momentarily to enga its contact, whereb limbS is grounded at this occurrin a ter the last impulse is transmitted over limb P b way of s ring 3. When dial 2 is at other than 'norma pin 3' is moved free of spring 2, which spring, by its tension, then disengages its associated contact, opening the conductive bridge of limbs P and S, the said calling device, on its return-to normal, again closing said contact 2'. Thus by successive actuationsof dial 2, a calling subscriber can transmit a number of sets of directive im ulses over limb P, each set being followed y a single "impulse transmitted over limb S.

t the exchange, the line circuit of the line of C may comprise the multiple terminals 41, 42, 43 (see Part 2), one, set of "multiple taps for said terminals being shown at 41, 42 and 43. It will be understood that the multiple terminals 41, 42 and 43 appear with those of nine other lines of the subgroup to which C belongs in one level 41, 42 and 43 of the other ninety lines of the group will appear by tens on different levels of the line selectors, which selectors have been assigned, as previously indicated, to the number of ten to a group of one hundred subscribers lines, as calling lines.

At K I have indicatcdthe circuits of a master switch mechanism which is preferdred lines and which serves the double purpose of selecting an idle line selector, the said line selectors being preferably not constantly line selector and transmitting directive impulses to the magnets thereof to place the Wipers of such llIle selector in connection a callin line, t is operation bein automatically e ected on the removal of t e receiver at the substation of such calling line.

Each subgroup of ten lines is provided with a group contact 28 before selectin arm 93 of the master switch, a common con uctor 92 extending from the group contact 28 of the subgroup by ten branches to contacts of armatures 14 of the ten linelrelays L R of a subgroup, itbein .understood'that each line is provided with its .individual line relay L R and its individual cut-off relay COR.

The line relay L B. when actuated responsive to the removal'of the receiver at the calling substation,;alters the electrical condition of the group contact 28 of its subgroup at the master switch K and also theconnections of its individual multiple private contacts 43 at the line selectors and the master switch K is started into operation, the said master switch first transmitting impulses to the primary or vertical magnet P MLof lineselector F to lift the wipers 45,

horizontal with the multi 1e contacts of the subgroup, among which t e calling line has its contacts, this lifting being controlled by the wiper 93 moving over the contacts 28 until it reaches a contact 28 whose conditionhas been altered by a line relay of its subgroup. At this time the vertical movements cease, and impulses are transmitted from master switch K to the secondary or rotary magnet S M .of the line selector, which magnet is used to rotate wipers 45, 46, 47 over the multiple terminal sets 41, 42, 43 of the selected subgroup until wiper 47 engages the contact 43 of the individual calling line, which contact, owing to the alterations of its connections by the operated line relay tions of the rotary magnet S M, whereby the wipers 45, 46 and 47 of the line selector rest-in connection with contacts 41, 42 and 43 ofrthe calling line, respectively.

- Each line selector of the ten pertaining to 1 a group of one hundred lines has a contact operating devices, and for starting the idle ably common to a calling group of one hunwith the multi le terminals 41, 42 and 43 ofv v 46 and 47 of such line selector to positions.

L R, is effective to prevent further actuaa the group wiper 93 may v in which the callin 31 individual to it before a wiper 29 of the I master switch K, which wiper normallyrests engaging the contact 31 of an 1dle line select'or and is as soon as such line selector commences its travel,.automatically moved over the contacts 31 in search of a contact belonging to an idle .line selector, thus traveling simultaneously with the started one.

I am aware that systems embodying-certain of the features above outlined have heretofore been proposed, and the present invention is directed more especially to the production of a system embracing certain preferred methods of'operation in such systems.

A feature of the present invention is' .found in the means provided for lockingthe line relay L R as soon as the same is operated responsive to the removal of the receiver atthe substation, said relay remain-.

in locked until the calling linehas been se ected. This will serve toprevent the .im proper operation of the group wiper 93 of the master switch K. The structures referred to as hitherto proposed are -of such character'that on the transmission of a flash signal produced by a calling subscriber removing and replacing his receiver quickly, move over allof its contacts 28 and remain hung up at its extreme operative position, there being then no means for restoring it to normal, so rendering the master switch mechanism unavailable for use by another subscriber, exce t by the aid of an attendant at the central 0 ce. Thus the transmission of a flash -signal might well cause the'master'switchK upon which all outgoing calls of one hundred lines are dependent, to be rendered inoperative, a contm nc which is eflectively prevented-by the ocklng of the line relay. in-the present system, as above indicated.

. his receiver, establishing a circuit "from ground at master switch K,, through the relay 16, armature 23, over common conductor 90 (having abranch'to each line relay of the one hundred lines served by K), line relay L R, armature 10, limb S of the line, contact 2", transmitter, the shifted hook lever, normal contact of ringing key 8, limb P, armature 11, to battery; relay 16 and L R are both operated,-the latter locking itself by armature 12 over a circuit extending to batter through normalcontact 9. Armature 13 isconnects cut-off relay O O R connectors and connects ground to said contacts, whereby the calling line is rendered busy against incoming calls. Armature 14 from the private multiple contacts 40 at the places aground upon. the group conductor 92 and upon the group contact 28 before the group selectin wiper93, it being as- I sumed that the calling line belongs to a subtheir contacts in the fifth oup havin fine selectors, the contact 28 of evels of the the subgrou 'being therefore the fifth contact engage by w1per93'in its travel from normal. Armature 15 in engaging, its alternate contact, has connected the release cona trol relay R C R of master switch K with the .individual private multiple contacts 43 of the calling line at the line selectors, to

render said relay sensitive to the engagement of the contact 43 at the line selector to be started by the private wiper 47 of such line selector. a

The energization of relay 16 completes the circuit from constantly traveling interrupter I through the back contact of armature of relay 17, attracted armature of relay 16, the

current then dividing, a portion flowing throughthe master switch wi er 29, the individual contact 31 ofthe id e line selector then enga ed by said wiper over conductor normal contact P O N, and through relay 100,to battery, the remainder of the current assing through the magnet M, controllin y its armature the pawl 30, and throu 1 the-conductor; 35 to battery at norma ly closed primary ofi' normal contact P O N.

The' relay: 100 by armature 102 is looked over a circuit extending through contact S S N, over the common conductor 32 (which conductor has ten taps 10, one to each of the relays 100 of the ten-line selectors serving a line group), thelocking circuit extending through normal contact 21,

through thewinding Of'SOlB'IlOld' 18, andrelay 17, to' 'grou'nd; the relay 17 then at- ,tractin its armature and connecting interr%pter to its front contact, whereby two e cots are produced. The first of these is a stepping forward of the master switch wiper 29 in search of the contact 31 of an idle line sel ctor F. This is effected by the opening of circuit through magnet M to allow its armature to be retracted if said circuit has not alreadybeen opened by travel of interrupter I, whereupon pawl 30 actuates a ratchet carried by the rotary shaft supporting the wiper 29, a step from left to right, wiper 29 being thereby moved from engagement with the contact 31 of the line selector F of Fig. 1 and into engagement with the next contact 31 pertaining to another line selector. If

this line selector is busy, its contacts P O N 36, throu the normally closed primary oil contact P O N will cause another steppin may be at rest, it being understood that the conductor 35 has a tap 37 to contact P O N of each line selector serving a one hundred line group. The impulse transmitted by interrupter I will cause anener 'zat-ion and denergization of the magnet next line selector, and if this be busy, the shifted condition of its primary ofl'. normal of wiper 29. The steppin of wiper 29 wi there ore continue by simi ar operations until the wiper engages a contact31 connected to a line selector whose contact PO N is in its normal condition, interrupter I being disconnected from such contact P O'N,=whenthe wiper will rest, engaging such contact 31, the master switch K, when restored to normal, as hereafter described, bein then ready to operate the selected idle ,11116 .se- Iector in search of the terminal of an idle line as soon as a call is initiated. It will be seen-that if all the line selectors of a line group are simultaneously busy, no travel of wiper 29 can be roduced, because, although the interru ter 7 primary 0 normal contacts P O N, the fact that all primary ofi' normal contacts 1? O N will be shifted will have openedall thebranch conductors 37 and there, will be" no return path for current through magnet M.

lVhile the wiper 29 isstepping as described, the interrupterv I is'transmitting impulses overthe front contact of armature of relay 17, back contact of armature25, t-hrou h ma net 19 to battery and over a" branc of t is circuit extending through normal contact 26, the common conductor 33, havin mature 101 of relay 100, through primary magnet P M .to battery. Each impulse ae- .t uates magnets 19 and P M,'magnet 19 with each actuation attracting its armature, 'to turn' escapement pawl 20- about its pivot, whereby its upper tooth disengages a tooth of ratchet 93, which then rotates a step under-tension exerted by core 18 of the energized solenoid 18. Successive actuations of magnet 19 allow successive steps of ratchet 93 and wiper 93, which engages'on each step, a successive group-contact 28. Obviously, for each step of wiper 93, an impulse passes through primary magnet P M to step the shaft and wipers 45, 46 and 47 of line selector F a step vertically for each step of wiper 93. This synchronized stepping of which Wlll step wiper 29 to engage contact 31 of the,

1 will be connected to all branches 10, one to each line' selector '0 the group, through attracted arwipers 93" a'nd wipers 45, 46 and 47 will continue until wiper 93 reaches a group contact 28 grounded at armature 14 of the line relay of the callin line 0. As soon as this occurs a circuit wi 1 .be completed from attracte grounded armature 14 over common subgroup conductor 92, the group contact 28, the wiper 93 engaging said contact, and through vertical control relay V C R to battery, actuating the said relav, whose armatures arelhcreupon attracte at 25 to 0 en the previously existin from interrupter I t rou h magnet 19,

through armature 26, and a so to open the previously existing circuit for ma et P M, armature 26 closing circuitcxten in from interrupter I throu h front contact 0 armature of relay 17, a ternate contact 26, conductor 34, which conductor has ten branches 10", one to each relay 100 of the ten line selectors of the group, throu h attracted armature 103 of relay 100 of t e'operating line selector F, and throughit to secondary or rotary'fmagnet S M, to. battery. Impulses'will continue flowin over this circuit, magnet S M being actuated to adjust wipers 45, 46 and 47 rotarily step-by-step over the multiple contact sets 41, 42' and 43. of the lines of the selected level until wi er 47 enages the private contact 43 of t e calling ineC,--.Wh1ch will be connected through attracted armature 15 ofline relay L It and circuit exten mg conductor 91, having one hundred taps, one

to'each line relay L R of the ealling line group, through release control. relay C B, to battery. j As soon as this occurs, the

ground upon wiper 47 causes energization of relay. 'R G R whose attracted armature 24 opensthel series circuit before mentioned, in-

;cluding relays 17 and and the solenoid 18, so that allthree are now dencrgized on the energization of relay R C R. The deenergization of the solenoid 18 renders the restoringspring associated with the ratchet 93 and wlper 93 effective to restore the same back to normal, while the armature of the connectors,wvhereby the calling line is continued to be held busy against incoming calls. 'On the deenergization of line relay L R, armature 14 removes ground from the group contact 28, and, by the retracted armature 15, relay R C R is dener ized,- so that the master switch mechanism is in its original or normal condition and ready to emcee serve any other calling line of the group in adjusting a line selector to connection with such line.

It will be observed that although the master switch wiper 29 seeks out a terminal 31- by the locking circuit for said relay established over the common conductor 32. No other calling line is able to actuate the relay 100 of another line selectorrF-until the first one has completed its selection, because the relay 17 continues actuated while the line selector is being adjusted and holds 'interrupter I disconnected from its back contact. Moreover, a downwardly extending arm of the wi r 93 on the first actuation of 35 said wiper, c oses a short circuit from the unded spring 21 and its contact about t relay 16 dei nergizing said relay, which short circuit will continue until the wi r contact 21 will be again opened.

Itwill be observed that while the line wipers 45, 46 were being adjusted, the relay. 44 washeld energized by a circuit extending from ground through attracted armature 86 104 of relay 100, the said relay 44, to bat- 'tery, whereby'the said line wipers 45, 46 were held on open circuit while wi 'ing over contacts 41, 42 of lines not wante and interference with possible conversations ex- 40'isting over such lines was prevented, said relay 44'bein r denergized as soon as the circuit throng 1 relay 100 was opened, as before rlrscrilxad, and its armature retracted. The energizationof relay C O R by attract- 46 ing'its armatures 0, 10 and 11, disconnected the line relay L R from limbs P S of the line, so that the same may be no longer'operable by current overjthe line limbs.

I have now expiained the operation. of the 5 structure including the master switch mechanism K, whereby responsive to the re-' moval of the receiver at the substation, a first selector G, linked with a line selector F,

is connected to the calling line, and the 5 manner in which the master switch mechanism K is thereafter restored to the use of any other line which may initiate a call to operate responsive to the line relay of such line, in connecting some other first selector W G with such other line, and shall now roreed to indicate briefly the o ration o the selector and connector, this general features of these being known in the art.

Tho culling subscriber, by rotating dial 2,

.5 will bring two teeth beneath spring 3, and

subscri rs" lines includii 93 reaches normal, as before described, w en on his releasing it, the dial transmits two impulses from ground E over spring 3 and its contact, key contact 8, over llmb P through contact 41,- 45, upper armature of relay 44, normal side swltch contact 50, 7o relay P R, to battery, actuating said relay twice. whose armature then transmits two impulses from ground through back contact of armature of side switch magnet S S M, primary magnet P M, magnet lifts the wipers 52, 53 and 54 of the:first selector two steps upward to position horizontal with a contact level includ ing contact sets cbnnected to secondselectors H assi ned for connections to a group of so numbers 2000 to 2999. On the return of ial 2, an impulse is transmitted,-as before described, from the earth E, through the contact 4,0ver limb S, contact. 42, 46, lower armature of relay 44, 33

normal side switch arm contact 51, secondary relay S R, to batter energizing and denergizing said relay w ose armature energizes and deenergizes side switch magnet S S M whose armature, by a well-known mechanical connection shift-s side switch arms 48, 49, 50 and 51 simultaneously from engagement with their normal contacts andto engagement with their middle contacts, it being understood that the shifting is accomplishcd on the hack stroke of the armature of magnet S S M. Secondary magnet S M is now actuated b current impulses flowing from interrupter 2 through said magnet, to

battery, said magnet being effective to step the wipers 52, 53 and 54 over successive sets of multiple contacts55 56' and 57 in search of a contact set of an idle second selector H. By a well -kuown mechanical connection, magnet S M on its first actuation, thrusts the nrmature'of magnet S 'S M into its attracted position. Ii the first contact set 55, 56v and 57 is idle, the armature of magnet S M will be retracted when the impulse through magnet S M ceases and the side no switch arms movedto their third contacts.

If, however, the first contact set perta ns to a busy second selector, multiple prlvate contact 55.will be grounded through the release relay RfR of some other first se1ect0r'115 G. rendering thesccond selector busy, and side switch magnet S S M of vthe seeklng first selector G will be energized over circuit extending through intermediate contact and arm 19 to wiper 52, the busy contact 55 to its multiple engaged by the first selector, rendering it busy, and ground through its release relay R R. -S1de switch magnets S S M and'release relays R R have their windings ,so proportioned that current over the just traced circuit, while producing suilicient encrgization of S S M to hold its armature attracted, does not produce sufficient energi-zation of release relay It R to cause it to attract its armature. As

to battery, which 75 long I et S M continues energized, thevside sw tch arms cannot-move to. their third positions, and successive circuits for holding said magnet energized are produced.

as .wipers 52, 58 and 54 pass over busy contacts of thefi'selectedlevel until wiper 52 engages a contact 55 pertaining to an idle second selector, which will be 'ounded,

, as shown in Fig. 1. At such time side switch '.magnet S S M vis deenergized and the arms 48, 49, and 51 pass from their intermediate positions to their respective third or sitions, whereby secondary m et connected through the winding of release relay R R 'and the third contact of arm 49 taper 52 and the multiples 55 of the se-,

to lect second selectorzH, rendering it b Arms 50 and .51 extendto the eircuit of e calling ubscribers line, through to rimary relay R andsecondary relay, S selected idl'e second selector.

The calling subscriber C now actuates' dial 2 to transmit three im ulses over limb P followed by one on limb ,Jthe three passmg through arm- 50 and its third contact, contact 53, 56,-arm 60, primary relay 'P R, to battery, which relay t'ransmitslthree impulses through primary magnet P M, which adjusts wipers 66, 67, and 68 of second selector H, to positions horizontal with the level of contact sets extending to connectors L assigned for connection tothe third one hundred grou" of the, second thousand group, one im uding lines numbered from 2300 to 2399. The impulse over limb S passes throu h at ",'51 and its third contact, contact 54, 5%, a '61, secondar relay S R which relay'S R attracts an releases, its

and deenerglze side armature 64 to ener'ize whereby theswiteh switch magnet S S arms 58, 59, 60, 61 are shifted to their intermediate tion of t lected group will proceed in the same manner as that of the' idle second selector-by the first selector, as already described. I

On selection'made, the s1de switch wi rs 5s, 59, c0 and 61 will be shifted to tli third ositions and four impulses now trans- 'nitted from the calling substation over limb P will pass through contact 53, 56, arm 60 and its third contact, contact 67, 70, thence over the heavily marked conductor armature 79 and its back contact, through prima relay P R, to battery, which relay, attracting and releasing its armatures four times, closes circuit four times from ground through attracted armature 75, normal contact'76, side switch arm 83 and its normal contact, primary magnet P M, to battery,

positions, and the automatic selecwhich magnet adjusts the wipers 105, 106,- 107 four stepsvertically to positions opposite a :level of contact 'setsooin rising those of linesnumbered 9841 234 normal contacts downward to eng of the g middle contact, seconda battery-,which magnet Wlll stepwi rs 105-,

' escribe first idle connector L ofthe seeir act will relay -.P

followed by amiss of 1ine 2340, it being understood that zero is represented by ten impulses in automatic tele hone systems. The impulseover limb S o the line of C, h

following the four over limb P, will pass through. side switch arm 61 of switch H and its th rd contact, through contact 68, 71, con v its'armature 73, to energize and deenergize side switch magnet S S M ofothe connector, whereby the side switch arms 83, 84,85 and 86 are 'shifted'from their e t eir intermediate contacts. n Five impulses now transmitted from sub-- station. 0 over limb' P will pass over the before-traced path,through rimary relay P R", whose armature .75 will be attracted and released -fivetimes'to transmit five impulses via. normal contact*76,- arm 83 and its ,magnet S M, to

106 and 107.five steps in a rotary irection, the fifth step bringing them to engage the multi le contacts 40,39 and 38 of "line 2345,. 7 name y, the line at D. -A single impulse over limb S following the five over limb P,

asses over the before-traced path, ener iz-- in and deener izing the secondary re ay S which W111 ener ize and deenergize side switch magnet S S%'I ,whose-energ1zation now causes the called line to be tested as to its idle or busy condition. V It being 'firstassumed that the called line D is idle the bus line operations to be hereinafter d on the deenergization of magnet S S M, the side switch arms83, 84,85 and. 86 .w'ill be shifted to their third posit-ions,

:arm 84 in engaging its thirdcontact con necting groun over wiper10 5 to" the multile contacts 40 of the called-for line, renering the saidline busy against incoming calls and also o' crating 'the cut-off relay 7 C O R of said ca led line over a ci rcuit extending from battery. throughlsaid relay ,C' O R, normalcontact-13 of line relay L R,

R of the cal e'd-for line is o eratively dissociated from said line.

'l ie calling subscriber C now depresses key 8' to ground limb P of the line, which p'oduce' an energization of primary 8 in the before-described manner, said relay being energized, and by its arma-' ture 75, closing-circuit through normal contact 76, armature 83 and its thirdcontact, generator relay G R, to battery, the said re ay' being energized as long as the subscriber C keeps key 8 depressed to include, by its armature 85, 86, the alternnting'current generator G in circuit with the called-for line, current therefrom passin out over the line and actuat' the call be at the'substation. rJThe call 2 subscriber having been sigcontact 40,105., to round throu h arm 84, whereby line relay -whereby primary relay P R and relay R are deenergized. When now the called subever, is a cumulative relay and; its armatures ferential relay R R remaining inert. The

' battery being supplied to their transmitters" i I this of his res *through arm 86 and its third contact,con-

' relays -the calling line as ollows:

naled, the calling subscriber releases ke *8, I

scrlber responds, the removal of his receiver. permits hook lever 1 to complete a conduc: tive bridge of limbs P and S at his substa tion, whereupon current will flow as follows: from ground at switch L, through lower winding of release relay R R, lower winding of control relay C R, through nor mal contact of lower armature of relay G R,

tact 107, 38, over limb P of the called line, through the transmitter supplying talking current thereto, returning over limb S, contacts 39, 106, side switch arm 85 and its third contact,;normal contact of'upper armature 'of rela G R, through upper windings of R and R R, to battery. The relay R R" is a differential relay, and having equal current flowing through its two windings, its core remains inert. Therelay C R, howare attracted, -whereupon.78, 79 complete a circuit for supplyin talkin battery vto rom ground, through the u per winding of the difierential release re ay R R theimpedance coit shown, through attracted-armature 79, over conductor contact 7 0,67; 56, 53; 4'5, 41; 7

over limb-P and through substationof C, the transmitter being included in this circuit, returning over limb S, contacts 4246, 54-57, 68-41, over conductor 71, through secondary relay S R, attracted armature 78, lower winding ofrelay R R to battery, diftwo subscribers are now in conversation through condensers-81, 82 interposed in the talking conductors of the connector, talking from a-central source through the suitable inductive resistances. included in the circuits just traced. When the subscribers finish their conversation, they replace their re ceivers on the hook switches, the hook levers 1 by their'respective arms 1, which, on'the removal of the receivers pass to the left of the spzing 5, now cause the springs 5, 6 and 7 to momentarily connected together until the arms 1 pass over the top of the to their normalpositions shown. means it is apparent that when either subscriber replaces his receiver, the act is effective to simultaneously und for a short space of time the two line limbs P S tive line. When subscriber D replaces his'receiver, the act is efiective to restore the connector L only to normal. When subscriber C replaces his receiver, the act is effective to cause the restorations to' normal of lineselector F, first selector G and second selector H.

Assuming the calling subscriber. Cfirst replaces his receiver, the simultaneous grounding of limbs P and S will cause current to be shunted from the upper winding of release relay R R at connector L, and undiminished current will flow in the lower winding thereof over limb S and to ground of the substation. The said relay R R- will therefore have its core magnetized and its armature will be attracted to close a circuit from ground through said armature, through primary relay P R to battery. Relay S R eing already energized, 'bein included in the circuitof the lower win ing of relay RR, a restoring circuit is now completed from battery through attracted armatures 72 and 74 over release wire 69, contact 69 -66, arm 59 and its third contact, release relay R R of second selector H, to ground, the said relay attracting its armature and closing a circuit from battery-through release magnet R M attracted armature of R. R through contact 5552, to switch G, side switch arm 49v and'its third contact, release relay R R to ground, which relay, by attracting its armature, causes simultaneous energizations of release magnet R M of the first selector G and of magnet vR M of the line selector F.- It may be here stated that the'line selector F'is restored to normal on the forward stroke of its release magnets armature, being in this respect similar to the connector mechanism of the atent hereinbefore referred to, while the rst selector G and second selector are restored on the back stroke of the armatures of their respective release magnets. Thus when magnet .R Mv of line selector.F is energized, it*

closes circuit through1magnet 44, whereby the line wipers 45, 46 are placed in open cirunit, and as the magnet is fully actuated, the wipers are rotated in the reverse direction free of the contact bank, and descend to their normal levels, in the well-known manner. The magnet 44 is preferably rendered slow to release its armatures, in any of the well-known ways, in order to insure the wipers 45, 46 continuing on open circuit until they have been moved clear of the contact s'etsof lines not wanted. As soon as relay 44. is operated. if ground has'not already been removed from the 'line at the substation,

in which case relays P R S R will have already become de'e'nergized, the said relays have their circuits opened, and the retraction of their armature's opens the beforetraced circuit through relay R R at switch H. This relay becomingdeenergized, opens the before-traced circuit through release magnet R M (which is deenergized to restore switch H) and release relay R R,

whose retracted armature opens the circuit of magnets R M and R M, the deenergization of the latter restoring the switchGto normal, it beingunderstood that in the case of the switches G and H the deenergization of the release magnets notonly restore the 40 beenopen at side switch arms 85, 86 and the armatures of said relay retracted. When-un,-

wi iers, but shift the side switch arms to norma The oil normal contacts 0 bland O N? at the connector L were shifted on the first vertical step thereof, in the well-known manner, the shifting of spring 0 t N placing a ground upon the back contact of armature 7 4, to the end that if the calling subscriber first replaces his receiver as just described, thedeenergization'of relay P B would, by armature 74, continue a ground connection upon multiple contacts 69 of the connector L at the second selectors, so that the connector L will continue busy with res ect to any other second selector until the cal ed-for subscriber, by replacing his receiver, restores the connector to normal. When he replaces it, the grounding of the two line limbs at sprin the called substation D shunts current from the lower winding of release relay R R,

while current continues flowing through the upper winding thereof, to ground, through 7 at the substation, whereby the relay R. is unbalanced and its armature attracted to close circuit through release magnet'R-M, which. is actuated to restore the wipers of connector L and its side switch arms to normal on theforward stroke'of its armature. When this occurs ofi normal contact O N (and contact 0 N) are shifted, the

former to remove the busy ground from multiple contacts 66 so that the connector L P R, to battery, and through relay through normal contact 78, to battery." The and S R would cause the switches is thereafter selectable and availablefor use in the putting through of some other connection. I i

If the called subscriber D had replawd his'receiverin advance of the calling subscriber C, the connector would have been restored to normal, as above described, and the'circuit of control relay C R would'have der these circumstances the line limbs at substation C" were simultaneously grounded relays P R and S R would be energized by current from ground at substation flowing through armature 7 9 and primary 'ellary simultaneous energizations of relalyI G and F .to be restored in the manner'heretofore described, .Such simultaneous ener 'zation would also close a circuit from attery, through release magnet R M,.through normal contact 80," through alternate contact 76 (SidG'BWitOh magnets S S M bein energized because S R is energized), rough attracted armature 75, to ground. e actuation produced thereby of magnet R M is underthe present circumstances ineflectiveyas the connector'has already been re leased by the called-for subscriber. This, however, is the circuit for releasing the connector controlled by the. calling subscriber,

.In any of these cases which is used should the called-for subscriber fail to answer the call or should the line of the called-for subscriber be found busy. It should be noted at thispoint that the control relay C R, which relay is energized on the response ofv the called subscriber, by attracting its armature 80, is a means for reventing the release circuit of magnet R I from being completed by the simultaneous energizations of relays P R and S R as long as the called-for subscriber has his telephone off the hook.

I will now explain the conditions arising when the 'called for line is busy. If the said line is busy because a selector, such as F, is traveling in search of terminals of the line as a calling line, the private multiple called contacts 40 of the said line will be grounded atattracted armature 13 of its line relay 1 L R. Ifthe line is busy because a line selector has selected said line, the multiple contacts 40 will be grounded through back contact of armaturel3 of line relay L .R,

vback contact of armature 15, to contact 43 47 of the line selector, to ground. If the called linebe busy because another connector L is already connected thereto, the multiple private contacts 40 will be grounded at the third contact of side switch arm 84 of the connector, rendering the called line busy.

as soon as the'last impulse from ground at the calling substation flows through relay S R as before described, I

which relay energized .side switch magnet S S M, a circuit for release magnet R M of the connector will be completed extending from battery throu h said magnet, normal contact 80, attracted armature77,side switch arm 84 then engaging-its intermediate contact, through wiperv and to ground through the busy multiple contact 40 of the called-for line. The energization thereby produced of magnet R M restores the connector and the side switch arms. When,

therefore, the calling subscriber C depresses ringing key 8, the grounding of limb P thereby produced is effective merely to step the shaft of the connector upward one step, inasmuch as switch arm 83. has been restored. The subscriber at C on releasing the button, listens and receives from the busy bacli device B B, the busy signal, the oil normal contact 0 N having been shifted on the upward. step to inductivel connect the said device with the calling su scribers line over circuit extending throughnormal side switch contact 1 85,-through' condenser 81,

over the talking circuit and through the callsecondary rela S R? and- armature 7,8.

"ingsubstation, returning to battery through Hearing the signal, the" calling subscriber replaces his receiver, and this act is effective to again restore to normal the line D 'connector' L byuclosing the circuit of release magnet R before described, and also I able for use in put-ting through other con 5 emcee efiective, as before described, to restorethe other switches used in the connection to normal. a v

'- If the calli subscriber hasqremoved his 5 receiver and a me has been selected byline selector F, and said subscriber then deter mines that he does not desire to put throu h the contemplated call, the replacin ,oft e receiver and the con uentnsim '1. grounding of limbs P an S will be. efiective to one as simultaneously relays P R and,

S R o the first selector, the energization of relay S R,-'in turn, energizing magnet S S M, whereu on a circuit will be completed ,from 11 through attracted armatureof relay R alternate contact of armature of et, S S M, through release magnet R of line selector F, to battery, actuating the said release magnet and restoring the line selector to-normal.' If the calling subscriber chantges his mind after transmitting a portion ,0 the impulses required to complete a contemplated connection and replaces his receiver, the operating relaysof will complete restoring circuits for all switches to that time moved ofi normal;

receiver while relays P R and, S R? of second selector H are connected with the limbs of his line, the simultaneous energizetion of said relays will roduce Jacircuit extending from battery t rough release mag- 85 net. R ,M, attracted armatures 65-433,

through contact 55--52 side switch arm 49 and its third contact, through release relay R R ofswitch G, to round, whereupon the restorations of switchesH, G and F will proceed, asbefore described,

As hereinbefore indicated, one hundred lines depend for their 'connec'tions'as calling lines upon the master switch K. While by lockin the mischievous efl'ects produc provide additional safe-guards against the possibility of a flash'signal being sent, and

the lockin apparatus. Under these circumstances the group wiper 93 will, of course, not find any contact 28 grounded andwillroceedato its extreme operative osition. W en it reaches 56 this position, whic is a step be and the last group contact, the downward y. extending arm of wiper 93 will be in a 100 and solenoid 18, and the. m ls er .s'witc K will be restored to. normal and be av'aiL taneous whatever selector is then connected with his line will be simultaneously energized and Thus if the calling subscriber replaces his" up of the line relays I have reed by' circuit proving inefl'ective by" some misc ance or defect in the line relay;

sition .engaging spring 22 and closing sai spring to, connection with its associated contact, whereby to release control relay B Cv R will have'its.

- circuit closed, and by becoming, energized, will open the locking circuit including relax first vertical tep, and restored to disengage its contact ;when the line selector reaches normal, Thus, when magnet'R M'is enerby accident put out of service, I provid'e in 3 the mechanism of the line selector. F the primary or vertical subnormalor over-run switch P S N, which enga es its contact on an eleventh vertical stcpo the line selector, it being understood that the connector of thepatent referred when used for line selecting purposes, has preferably eleven verticalratchet "teeth and an arm on its shaft to actuate; s ring P S 'N on an eleventh step. I Thus s oul armature 14 of an actuated calling line relay fail to make its contact,

line selector F would make eleven vcrticalh} steps and close'contact P S N to energizejaa magnet R' Mto restore the line selector,

wiper 93 of K being restored in the manner already mentioned. It mi ht happen that armature 15 of an actuator? line relay would fail to' make its alternate'contact, in which case, su posing. arm'aturef14 to have acted proper line selector F would turn its wipers in onthe proper level and would find no terminal 43 of a line connected to battery through release control relay'R C R, and the -line selector would go to an extreme rotary position and there remain hung up, the master,

switch with 93 being also hung upon the fifth contact 28-,were it not for the secondary or rotary subnormal or over-run springs S S N; and S- S N. These areshifted," S S N to disengage its contact and S S N to en age its contact-on an'eleventh rotary step 0? the line selector by a suitable arm on the shaft of the line selector, which a will have eleven rotary ratchet teeth instead of th'usual ten. Should the line selector, on account of-th contingency referred to,'or some other, make, an eleventh rotary ste ,the shifting of contact 88 N willopen t e circuit of-relay' 100 and solenoid 18, the dee nergization' of the latter restoring .wiper 93, while spring ,S S N? engagirfiits contact, will energize. release magnet M to restore the line selector. v The contact P O N is. the ordinary otf normal shifted to engage its contact on, a

by" its ,right armat ure, remain ocked. until the. line so ector reachesn'ormal jand; may, will also continue energised" I no till such lIlllle, holding wipers 45, 46 on open circuit. 7

When spring P O N is emgloyed, obviously, it is unnecessary to ren 44 slow to release its armaturesfas before described. Either method for v keeping wipers 45 and 46 on open circuit .durmg restoration may beeemplo ed.

While I' have used a p urality of battery therewith, a master switch mechanism, common to said switches and lines including a travelin member to select an idle switch, a secon I traveling member for said mechanism operated independently of said first member and serving to control travel of the selected selective switch, line relays for said lines at the exchange, each relay iservin when. energized, to temporarily individua in said master switch mechanism to its call-' ing line, terminals of said lines at said selective switches normally unselectable in operated -line relay of a calling line 'to render itslines terminals selectable at said switches, apparatus controlled by said relay for. determining the travel of said second member, and a locking circuitfor each line relay servingiafter inltial operation, to continue the re ay energized until its-line is selected', I

2. telephone cuits at the exchange, selective switches less in number than the-lines to select. calling 3 lines to connect idle link circuits therewith,

a master switch mechanism, common to said switches and lines including a travelin traveling member for said mechanism operated independentl of said first-member and serving to contro travel of the selected selective switch, 'electro-magnetic means at the:

exchange operated responsive to vcurrent control to render an idle selective switch operative,

said means including the lines line rela-y,-

controlled by said relay for de-- apparatus to the travel of said, second memher, and alockin circuit for each line relay after initial operation, to. continue the re ay energized until its line is selected. 3, A telephone lines, a line rela or each said line, 1i circaitsa tthe-ex a ,selective switchesless;

:in number., thanj.the to select calling er the relay character,'-switchin'g means controlled by the fysl ni includin tea hone: 1ines,'a line relay or each said line, lin cirstein including tele hone.

-amaster switch mechanism,common to sai member to select an idle switch, said mem-' ber alsoserving as part of a circuit to render the selected switch operable, a second ated independently of said first member and lective switch, electro-magn'etic means 'at the controlled att-he substation of a calling line to render an idle selective switch operative, said means including the .lines line relay,

servin ,after initial operation, to continue the re ay energized until its line 'is selected. 4, A telephone system including telephone switches lessin number than the lines to select calling lines to connect idle link circuits therewith, amaster switch mechanism, common to said switches and lines including a traveling member to select an idle switch, a second traveling member for said mechanism operated independently of said first member and serving to control travel of the when energized, to temporarily individua JZG'Sflld master switch mechamsm'to its callmg hne, termmals of sald lmes at said secharacter, switching means controlled by the operated line relay of a calling line to render its lines terminals selectableat-said switches, apparatus controlled by said relay member, circuit connections for stopping a selective switch when engaging the terminals of a line rendered selectable, means effective' on selection made of a calling line, to restore said mechanismto common use of said lines, and a locking circuit for each 'line' relay servin after, initial operation,

to continue the re ay energized until its line member to select an idleswitch, a secon common-to said switches and lines including a traveling'member to select an idle switch, a second traveling member for said mechanism operated independently of -s'aid' first member and serving to control travel of the lines at the exchange, 'each rela when .energized, to temporarily in ividualize said master switch mechanism to its calling calling line, to restore said mechanism to lines to connect idle link circuits therewith switches and lines including a traveling.

serving to control travel'of the selected seexchange operated responsive .to current and a locking circult for each line relay selectfcalling lines to-connect idle link cir-- f cuit's therewith, a master switch mechanism, at the'substatlon of a calling line.

selected selective switch, line relays for said serving,-

traveling member for said mechanism operlines, link circuits at the exchange-selective selected selective switch, line relays for said lines at the exchange, each relay serving,

*lectiveswitches normally 'unselectable in for, determining the travel of said second ,5. "A telephone system including telephone l1nes,-link circuits at the exchange, selective mon ,juse said lines, andaflo'ckingcin line,'meanseflecti've.cnselection-made of a to said switches and lines including a traveling member to select an idle switch, a second traveling member for said mechanism operated independently of said first member and serving to control travel of the selected se-' 'lective switch, electro-magl'ietic means at the exchange operated responsiveto current controlled at the substation of a calling line to render an idle selective switch operative, said means including the lines line relay,

apparatus controlled by said relay for determining the travel of said second member, terminals of said lines at said selective switches normally unselectable in character, switching means controlled by the operated line relay of a calling line to render its lines terminals selectable at said switches,

and a locking circuit for each line relay serving, after initial operation, to continue ,the relay energized until its line is selected.

7. A telephone systemincludin telephone lines, a line relay for each sai line, link circuits at the exchange,'selective switches less innumber than the lines to select calling lines'to connect idle link circuits therewith, a master switch mechanism common to said switches and lines, a traveling member included in said mechanism serving to controlthe extent of travel of an idle selective switch, electro-magnetic means at the exchange operated responsive to current con trolled at the substation of a calling line to render an idle selective switch operative, said means including the lines line relay, apparatus controlled by said relay for determining the travel of said member, and a locking circuit for each line relay servin after initial operation, to continue the relay energized until its line is selected.

S. A telephone system including telephone lines, link circuits at the exchange, selective switches less in number than the lines to select calling lines to connect idle link circuits therewith. a master switch mechanism common to said switches and lines, a traveling-member included in said mechanism' lockingcircuit for each line'relay serving, after initial operation,-to continue the relay energized until its line is selected.

9. 'A telephone system including telephone lines, link circuits at the exchange, selective switches less in number than the lines to select salling lines to connect idle link circuits therewith, a master switch mechanism common to said switches and lines, a traveling member included 'insaid mechanism serving to control the extent of travel'of an idle selective switch, line relays .for said lines at the exchange, each relay serving, when energized, to temporarily individualize said master switch mechanism to its calling line, terminals of said lines at said selective switches normally unselectable in character, switching means controlled by the operated line relay of acalling line to render its lines terminals selectable at said switches, apparatus controlled by said relay for determin ing the travel of said second member, circuit connections for stopping a selective switch when engaging the terminals of a line rendered selectable, a locking circuit for each continue the relay. energized until its line is selected, other link circuits and selective SWItChGS 'thGIBfOI' including connectors for connectln dlrectly wlt-h called lines, means for electrically adjusting automatically se- .lected ones of said switches, including a connector, to establish a talking circuit between a selected calling line and a desired called line, mechanism responsive to currents .overthe calling line to restore said switchesto normal prior to a response at the called station, and means controlled on response at the called station to remove the-control of restoration-of the connector from the calling line and turn it to the called line.

10. A telephone system including telephone lines, link circuits at the exchange, selective switches less in number than the lines to select calling lines to-connect, idle link circuits therewith, a master switch mechanism common to said switches and lines, a traveling member included in said in character, switching means controlled by the-operated line relay of a calling line to render its lines terminals selectable at said switches, apparatus controlled by said relay for determining the travel of said member, circuit connections for stopping a selective switch when engaging the terminals of a line rendered selectable, a locking circuit for each line relay serving, after initial operation, to col'itinuc the relay energized until lines,

its line is selected, other link circuits and selective switches therefor including connectors for connecting directly with called lines, means for electrically adjusting automatically selected ones of said switches, including a connector, to establish a talking circuit between a selected calling line and a desired called line, said circuit also including the selective switch 'in connection with the calling line, mechanism responsive to currents over the calling line to restore said switches to normal prior to a response at the called station, means controlled on response at the called station to remove the control of restoration of the connector from the calling lin'e andturn it to the called line, and a circuit connection for thereafter holding said connector busy until restored by current over the called line.

11. A telephone system including telehone lines, a line relay for each said line, ink circuits at the exchange. selective switches less in number than the lines to select calling lines to connect idle link circuits therewith, a master switch mechanism common to said switches and lines, a traveling member included in said mechanism serving to control the extent of travel of an idle selective switch, electro-magnetic means at the exchange operated responsive to current controlled at the sub-station of a calling line to render an idle selective switch operative, said means including a line relay, apparatus controlled by said relayfor determining the travel of said member,- terminals of said lines at said selective switches normally un' selectable in character, switching means controlled by the operated line relay of acall ing line to render its lines terminals selectable at said switches, circuit connections for stopping a selective switch when engaging the terminals of a line rendered select-able,

other link circuits and selective switches therefor including connectors for connecting directly with called'lines, means for electrically adjusting automatically selected ones of said switches, including a connector, to

' establisha talking circuit between a selected calling line-and a desired called line, mechanism responsive tocurrents over the calling line to restore said switches to normal prior to a icsponse at the called station, and means controlled on response at the called-station to remove the control of restoration of the .i

connector from the calling line and turn it to the called line.

12. A telephone system phone lines, linkcircuits at the exchange,

selective switches less in number than the lines to select calling lines to connect idle. link circuits therewith, a master SWltCh' mechanism common to said switches and a traveling member 1nc1uded-.1n said mechanism serving to control the extent of travel of an idle selective switch, electroincluding telemagi-relic means at the exchange-opt-radial responsive to current controlled at the substation of a CtllllIlfI line to render an idle SBlBCt-IVG'SWltCll operable, said means also serving to control the travel of said member.

other link circuits and selective switches therefor including connectors for connecting directly with called lines, means for electrically adjusting automatically selected ones of said switches, including a connector, to establish a talking circuit between a selected calling line and a desired called line, mechanism responsive to currents over the calling line to restore said switches to normal prior to a response at the called station, and means controlled on response at the called station to remove the control of restoration of the connector from the calling line and turn it to the called line.

13. A telephone system including telephone lines, link circuits at the exchange, se-

lective switches less in number than-the lines to select calling lines to connect idle link circuits therewith, a master switch mechanism common to s aid switches and lines, a traveling; member included vin said mechanism serving to control the extent of travel of an idle selective switch, electromagnetic means at the exchange operated responsive to current controlled at the substation of a calling line to render an idle selective switch operable, said means also. serving to control the travel of said member, other link circuits and selective switches therefor including connectors for connecting directly with called lines,'means for electrically adjusting automatically selected ones of said switches, including a connector,

to establish a talking circuit between a selected calling line and a desired called line, mechanism responsive to currents over the calling line to restore said switches to normal prior to a response at the called station. means controlled on response at'the called station to remove' the controlofrestoration of the connector from the calling line and turnitto the called line, and a circuit connection for thereafter holding said connector busy until restored by current over the called line.

14. A telephone system including telephone lines, link circuits at the exchange, selective switches less in number than thelines to select calling lines to connect idle link circuits therewith, a master switch. mechanism, common to said switches and lines including a traveling member to select an idle switch, a second traveling member for said mechanism operated independently of said first member and serving to controltravel of the selected 'selective switch, electro-magnetic means at the exchange operated responsive to currentcontrolled at the substation of a ,calling line to render an idle selective switch operative,- said means ineluding a line relay, apparatus controlled by said relay for detcrininii'ig the travel of said second member, terminals of said lines at said selective switches normally unselectable in character, switching means controlled by the operated line relav of a calling line to render the lines terminals select switch in connection with the calling line,-

mechanismresponsive to currents over the calling line to restore said switches to normal prior to a response at the called station. and means controlled on response at the calledstatio'n to removethe control of restoration of the connector from the calling line and turn it to the called line.

15. A telephone system including telephone lines, link circuits at the exchange, selective'switches less in number than the lines to select calling lines to connect idle link circuits therewith, a master switch mechanism. common .to said switches and lines including a traveling member to select an idle switch, a second traveling member for said mechanism operated independentlv of said first member and serving to control.

travel of the selected selectiveswitch. andmeans vfor automatically restoring said second member to normal whenit travels to an extreme operative position. v

16. A telephone system, including telephone lines. link circuits at the exchange, selective switches less in number than the lines to select calling lines 'to'connect idle link circuits therewith, a master switch mechanism common to said switches and lines, a traveling member included in said mechanism serving to control the extent of travel of an idle selective'switch, and means for automatically restoring said'member to normal when it travels to an extreme operative position.

17. A telephone system including telephone lines. link-circuits at the exchange, selective switches less. in number than the lines to select. calling lines to connect "idle link circuits therewith, a master switch mechanism, common to s'aidswitclies and lines'inclu'ding a traveling member to select an idle switch, a second traveling memberfor said mechanism operated. independentlyof said first member and serving to control travel of the selected selective switch, electro-magnetic means at theexchange operated responsive to current controlled at the substation of a calling line to render an idle selective switch OPGIiIblQ, said means also serving to control the travel of said second member, and means for auton'iatically restoring said second member to normal when it travels to an extreme operative position.

18. A telephone system including telephone lines, link circuits at the exchange, selective switches less in number than the lines to select calling lines to connect idle link circuits therewith, a master switch mechanism common to said SWRt'llPS and lines, a traveling member included in said mechanism serving to control the extent of travel of an idle selective switch. electro magnetic means at the exchange operated responsive to current controlled at the sub station of a calling line to render an idle selective switch operable,-said means also serving to control the travel of said member, and means for automatically restoring said second member to normal when it travels toan extreme operative position.

19. A telephone system including telephone lines. link circuits at theexchange, selective switches less in number than the lines to select callinglincs to connect idle link circuits therewith, a master switch mechanism. common to said switches and lines including a traveling member to select an idle switch. a second traveling member .for said mechanism operated independently I of said first member and serving to control traveljof the selected selective switch, mul- I tiple terminals for said lines'atsaid switches d vided lnto groups, means for adpisting an idle selective switch to select a roup of terminals including those of a calling, line,

an over-run switch for said switch actuated an idle switch, a second'traveling member for said mechanism operated independently of said first member and serving to control travel of, the selected selective switch-multiple terminals for said lines at-saidswitches divided into groups, means tor adjusting an idle selective switch to select agroup of terminals including those of a calling line, and an over-runl switch for said switch 210- tuated-when said switch'passes its extreme group selecting position to automatically ref store the switch.

'21. A- telephone system including 'telei 'phone lines, link circuits at the exchange, 1

selective switches less in number than the lines to select calling lines to connect idle link circuits therewith, a master switch mechanism, common to said switches and lines including a traveling member to select an idle switch, a second traveling member for said mechanism operated independently of said first member and serving to control travel of the selected selective switch, mulfrestore said switch and also cause restoration of said second traveling member of said master switch mecl'ianism.

22. A telephone system including telephone lines, link circuits at the exchange, selective switches less in number than the lines to select ealling lines to connect-idle link circuits therewith, a master switch mechanism common to said switches and lines, a traveling member included in said mechanism serving to control the extent of travel of an idle selective switch, multiple terminals for said lines at said switches divided into groups, vmeans for adjusting an idle selective switch to select a group of terminals including those of a calling line said adjustment being controlled by said traveling member, means for thereafter ad 'justing said switch to seek connect-ion wit-l'i' the terminals of the calling line, and means actuated when said switch asses its extreme terminal selecting position to automatically restore said switch and also cause restoration of said traveling member of said master switch mechanism. 23. A telephone system including telehone lines, switch pairs common to said ines, each pair including a line selector,

master-switch mechanism common to said switch pairs and lines, said mechanism including means for selecting an idle switch air and means for t-ransmittlng a series of impulses to the line select-or of the selected pair, a line relay for each line adapted for energization to operate said mechanism, and a locking circuit for each said line relay.

24. A telephone system including telehone lines, switch pairs common to said ines, each pair including a line selector; master-switch mechanism common to said switch pairs and lines, said mechanism including means for selecting an idle switch pair and means for transmitting a series of impulses to the l ne selector of the selected pair, a line relay for each line adapted for energization to operate said mechanism, means at the substation of each line to energize its respective line relay, a locking circult for each said line relay.

25. A' telephone system including telephone lines, switch pairs commondto said lines, each pair including. a line-selector, master-switch mechanism -eommon to said switch pairs and lines, said mechanism including means for selecting an idle switch pair and means for transmitting a series of impulses to the line selector of the selected pan, a line relay for each line adapted for energiyiation to operate said mechanism, means at the substation of each line to energize its respective linerelay, and means rendering the operation of said meehai'iism thereafter independent of changes in the condition of said substation means. i

26. A telephone system including telephone lines, llne selectors to select said lines, master-switch mechanism common to said switches andlines', a wiper member for said mechanism ada ted to select an idle selector, a second and independently adjustablewiper member. for said mechanism ada ted to control the adjustment of the Selecte selector, line relays for said lin'es individual thereto and operable by currentsthereover,

'means for operating the wiper members of I I hereunto subscribe

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