US1270128A - Telephone system. - Google Patents

Description

F. W. DUNBAR, TELEPHONE SYSTEM.

APPLSCATION FlLED lAN.2\. HHS.

atontvd .huw 18, 1918.

FRANCIS W. DUNIBAR, 0F MANCHESTER, -VllllitlVOlQ'T, ASSIGNOR TO KELLOGG SWITCHBOARD AND-SUPPLY COMPANY, OF CHICAGO, ILLINOIS, .A CORPORA- TION OF ILLINOIS.

TELEPHONE srsrnivr.vr

Patented June 18, 1918i.

Original application led March 3, 1905, Serial N o. 248,242. Divided and this application led January 21,

To all lwhom t may concern:

Be it known that ,1, FRANCIS W. DUNBAR, a citizen of the UnitedStates of America, residing in Manchester, county of Bennington, State of Vermont, have invented certain new and useful vImprovements in Telephone Systems, of which the following is a specification. J n

My invention relatesvto telephone systems and has to do moreparticularly with systems of the type inwlich automatic switching devices are used inY completing connections between subscribers lines.

' The presentapplication is a divisional application of my application for Letters Patent, Serial No. 248,242, filed March 3, 1905.

Themain object of my invention is to provide means for distributing calls4 from calling subscribers lines to idle link circuits by means of successively operated automatic distributing devices. By usin a plurality of automatic devices successive y operable to connect a calling line to an idle link circuit, it will be readily seen that any one calling line is given access to a greater number of link circuits or trunks than if only one automatic switch was used to connect the*v calling line to a link circuit.

Other objects and features of my system will lbe hereinafter pointed out in 'the following speciiication and in the appended claims. a'

1 will explain my -invention more fully by reference to the accompanying drawing, in whichf The drawing illustrates the adaptability of the invention to one well known type of multiple switchboard, the invention, however, not being limited to multiple switchboard practice.

Each subscribers station,vA, B, is'provided with customary common battery sub scribers apparatus, a switch hook at leach station serving operatively metallically to unite the sides of the line when the 'receiver' 'is removed. I do not deem a detailed de# scription of the subscribers apparatus to be essential, as the illustration is sufficient to make the same understood by those skilled in the art. Although I have illustrated one arrangement of subscribers station apparatus, it will be obvious to those skilled in the art, thatother arrangements may be 'employed at the substations, and 1 do not Serial No. 212,920.

apparatus shown, nor do I wish to be lim? ited in all embodiments of the invention to. its application to a common battery system. The subscribers ,lines are` metallic lines (though the invention need not be limited to metallic circuits), said lines extending in two branches to the exchange, where they terminate in normal contacts 1-2 normally engaged by the armatures 11-21 of a cut-off relay 3. The contacts 1-2 are preferably in the form of spring arms that are adapted to engage contacts 12-13 when the armatures of said relay are attracted, such connection being broken when said armatures 11-21 are released.y The contacts 12-13A constitute the terminals of the oliice and of the line, which is' supplied with the; line jack 4:1. The system illustrated Abeing a multiple switchboard system, there are also provided upon other sections ofV the board than where jack 4 is located, other jacks 41 in similar connection with the contactsl tonsmS, which Contact button 7 being connected with a link circuit selector switch element, has a rotating arm 9 connected thereto, there bein one such arm 9 for each button 7, while t e contact buttons 8.are similarly connected with arms 10 similar to the armsv.' Certain local control to be' hereinafter specified, is obtained by the brush or contact 11. The activecontacts` 11-5-6 all move together. The brush 11 rides over contacts 12, each. preferably connected with a rotating arm 13. All of the link circuits at an operators position are in association with the arms 9, 10 and 13, the v talking strands of said link circuits terminating;v in contact buttons 14-15 engaged by the arms`9-10, respectively, while local circuit conductors associated with said link circuits are provided with Contact buttons 16l engaged by the arin 13. When the 'brushes 5, 6 and 11 stopat one-set of contactsincluding a button 7, a button 8, and

,a button 12, they are then adapted'to effect a signal at a free operators position, and in the preferred embodiment of the invention, are adapted automatically to be connected with a link circuit corresponding to said signal, there being desirably as many signals as'there are link circuits.

In the system shown in the accompanying drawing, the link circuit terminates at one end in the contacts 16-14-15 and at the other endvin a connecting plug, the arms 9-10-13 automatically selecting the link circuit in a manner to be hereinafter specified, the signal corresponding'to said link circuit -thereupon being effected, so that the 20' operator thereupon uses the connecting plug 17 corresponding to the signal.

Each line of a group of.. subscribers lines has as many buttons 7 as many buttons 8, and as many buttons 12, as there areoperators4 assigned or corresponding to such group. Each subscriber has thus assigned to him as many groups of switches 9-10-13 (with their associate' contact buttons) as there are operators, all of the switch arms -9-10-j13 corresponding to a given subscriber, being desirably mounted upon a shaft 18 of a link; circuit motor 19 that is brought into operation under conditions hereinafter to be set forth, when'the subscribers switches 5`-6-11 have become connected with Vthe arms 9-10f-13 corresponding to a free operator. Each subscribers line thus has a motor 1 9 that. serves to operate the switches 9-10-13 corresponding tol all of the operators," it being only such switches, however, that are connected with the switches 5-6-11 'that perform any function es a consequence of their operation. The switches 91--101131 correspond to another subscriber and extend to contact buttons similar' to contact buttons 7-8-12 copcrating with another subscribers switch including parts similar to parts 5-6-11. All of ,these arms 91-101-131 are adapted for simultaneous fifi operation by a -link circuit motor correspending to the subscriber to whom the elements 91-101-131 belong. By apparatus to vbe specified, the switch elements 5+6-11 are brought into connection with the arms 9-10-L5 that correspond to an operator whois free to take work, the said apparatus enabling the said switch elements 5-G-11 to pass by any arms 9-10-13 that are associated with the apparatus of an occupied operator. in order that the parts 5-6-1l may be arrested in their travel (their travel hai/"ing been commenced by apparatus to be specified), the cord circuits or link-circuits jointly control 'and eil'ect a circuit conditionv "that will cause-the motor mechanism operating the parts *5--6--11toi'ceasesuch opera.

tion when all ofthe link circuits that an operator is given to' use are not in service, the f said link circuits effecting another circuit condition when theyA are in use up to the capacity of the operator. v

Without at the present time describing the apparatus by which the result presentlyv to be stated is accomplished, I prefer to cause the link circuits belonging to each operator and the apparatus for the purpos governed thereby, to place grounds upon t e contact buttons 20 when all of said link circuits are group of buttons 20 a grounded button 201y with which the element 21' is normally engaged, so that the parts 5-6-11 may be moved at once upon the initiation of a call.l

The wiping portion of the element 21 is broad enough to engage one button before leaving the preceding, for an obvious reason. There is such a set of buttons 20 and a button 201 for each subscriber, each button of each set being associated with apparatus at one operators position, there thus being as many buttons in each set as there are operators positions or as there are sections of board. The buttons of the different sets (corresponding to the different lines) that are associated with the apparatus at oneI When a operators position, are multipled together, y

as indicated in the lower left-hand and lower right-hand corner of the drawing, so that any switch element corresponding to y element 21 riding over a set of buttons corl responding to the buttons 20, by coming into contact with the iirst button from which the ground has been removed, will cause the operation of the parts similar to parts 5--6-11 to cease.

I will later explain how the parts 9-10-13 willstop when they engage buttons 1415-16 that correspond tol an idle link circuit, and will also later describe the calling signal that is then operated.

I will now describe the apparatus by which the operation of the elements 5, 6, 11 and 21 is controlled.

A calling subscriber, as subscriber A, by

removing hisreceiver from its switch hook, establishes a circuit at the exchange which may be traced from the grounded armature 11, over the snbscribers line, to`the contacts p,

' cannot be further moved thereby.

2-21, the line relay 22, to the grounded battery 23, whereby the armature switches shown in association with said line relay are operated.. One of said armature switches 24 thereupon establishes a circuit through a winding 25 ,of a corresponding subscri'bers motor, which circuit may be tracedfrom the ground at 201, the switch 21, the conductor 2 7 connecting said switch with Athe front contactof switch 24, the lazy arm 28, between the bifurcations of which a projection of the armature 29 is located, the winding 25, to the battery 23. The ener ization vof this magnet 25 is intermittently e ected by reason of the separable relation of the lazy arm 28 and its contact, so that the armature 29 is intermittently operated to engage the teeth 30 mechanically. united with the switch parts 5--6-11-21. Thus, the first step is the movement of the part 21 from thegrounded contact button 201 into engagement with the next button. Now, if the operatorl with whose apparatus the said next button is associated is not free, there will also be a ground upon said next button, thereby still maintainingthe circuit through the magnet 25. If the neXt\ operator is fully occupied, the button 20 ycorrespondingl to her position or board section is also grounded and the movement of the parts 5-6'11-21 continued, this operation being carriedon until the brush element 21 comesinto contact with a 'button20 that corresponds with a free operator, whereupon circuit through the magnet 25 is etectively opened, by the removal of the ground from the corresponding contact buttons 20, so that the parts5-6-11-21 In the instance illustrated at the left of Fig. l, the very first button 20 encountered by the switch part 21 is supposed to be associated with an operator who is not fully occupied,

but who is free to put up more connections,

so that the circuit through the magnet 25-is opened to arrest the switch parts 5-6-11'- 21. The switch arms 9-10-13 that are thus ,connected with the parts l5-6---11 as indicated, are tho switch arms that are associated with the apparatus of the operator corresponding to the button 20 shown in conncction with the-element 21, whereupon the prime mover 19 is brought into service to move the said switch parts 9-10-13 to c0nnect the same with the'answering terminal buttons 14-15-16 that may be connected or associated with the link circuit of the selected operator that may be used in effecting connection between the calling and called subscribers, as l prefer an automatic connection between the answering end of the link circuit" and the calling subscriber, though that feature of my invention involving the automatic selection of the placeat which the calling signal is to appear is in itself a very important feature of the invention, particularly where the mechanism that is to govern this automatic selection of suclrlocation is jointly controlled by the link circuits. The

motor that is employed for the operation of including the electro-magnet winding of the element 31 may be traced from the grounded generator 33 vto be employed for operating ,said magnet, which generator is preferably a source of alternating current, to the back contact of an armature switch 34, the armature switch 35 and its front contact, to the armature switch 36 and its front contact, which is grounded. This circuit is broken at 34, however, during the time circuit is established through the magnet 25 because the magnet -37 is included in circuitwith switch 24, thereby removing the armature switch 34, preventing the closure of the circuitV through the generator 33. This connection 34 is provided because the magnet 38 is preferably employed. to operate the switches 71-81 temporarily to disconnect the parts 5 6 from the calling subscribers line, circuit being established through said magnet 38 bythe armature switch 39 engaging its front contact, the armature switch 40 engaging its front grounded contact, the magnet 38, thegrounded battery 23. It might be stated that Vthe armature switches 24-35-39 are governedby the' relay 22 and the armature switches 34-40 are governed by the relay 37. When the circuit through magnet 37 is opened at 21, circuit through the elements 31-33 is established by the release o the .armature switch 34 that thereupon engages its back 4contact, said circuit continuing from said back contact, through the armature switches 3LP-35, the front contact of armature switch 35, the armature switch 36, to the grounded contact of said latter armature switch. It is necessary to maintain the armature switch 36 in engagement-*with its grounded contact in the embodiment of the invention A illustrated, while the motor 19 is in operatiomin order that the ground at 36 may bennaintained to continue the establishment of the circuit containing the generator 33, to which end the back or normal contact of armature switch 40 is connected with the switchv elornent 1l, which determines the location of the ground supplemental to the ground at the battery 23 to establish'this circuit of said `magnet 38. By conditions hereinafter `to be set forth, the contact buttons 12 connected with the apparatus at the diii'erent operators positions or board sections, have grounds placed upon the 'same through the intermediation of the switch elements 13,

the Contact buttons-16 engaging said .switch 38 is maintained, and which may readily be traced 'as hitherto indicated. As soon, however, as' the iirst idle link circuit or the button ,16 co1, sponding thereto, becomes associated vwith "the arm 13, the ground is removed' from the element 11, causing the deenergization 'of the magnet 38, thereby removing the armature 3.6 from its grounded contact and opening the circuit containing the elements 31-33, so that the parts 9 10-13 remain in the position .they were brought to when vthe switch arm 13 engaged the vbutton 16 vfrom which the ground had been removed because of the idle condition of the link circuit associated with the said button 16 thus engaged. 'All of the operaa tors may be provided with the same number of link circuits, but the number of those cire cuits that may be brought into service may be limited by providing artificial means for placing grounds upon the buttons 16 or otherwise throwing the link circuits out of operative relation with the operating mechanism of the exchange, there being indicated in the embodiment of the invention shown, manually operated switches 41 thatv may be moved into connection with grounded buttons when the link circuits associated with said switch arms are thrown out of service. -When the arms 9-10 are arrested, conductors 42-43 o'l'an idle link circuit belonging'to afreev operator, are connected with the arms 9-10 and thereby with the buttons 7 8 and the switch parts 5-6 engaging said buttons, so that the calling line is connected with said link conductors 42- "3 1, the switch element 5, the button 7, the

traveling switch 9, the link conductor 42 {in this case the sleeve' strand of a cord circuit), the relay 48 (which becomes thereby energized), to the grounded battery 23. The subscribers apparatus now effects an opera.-

tion of the calling signal 44, because the aru -line of the callin mature 45 ofthe supervisory relay 46v of the calling end of the cord is nowumattracted, and because the relays 47-48 are energized, whereby circuit may be traced :from4 the grounded terminal of the signal 44, preferably a small, lamp, through the armature switch 49, the armature switch 45, the arF mature switch 50, to the grounded battery 23, this saine circuit including a relay 51 common to a plurality of circuits containing the signals 44 to operate a common signal The circuit through the relay 47 may be traced from its grounded terminal, over the link conductor 43 (in this case the tip strand of a cord circuit), to a button 15, ,the engaging arm 10, a button 8, the engaging switch element -6, thence by way of the armature sol switch 71 and its contact, over the telephone l subscriber, the armature switch 81, the swltchl part 5 andv engaging button 7, the switch arm 9.'and engaging button 14, the link conductor42, to the battery 23 by way of the magnet 48.A rlhe supervising apparatus and the balance of the operators apparatus associated witlfthe.

connectinfr end of the cord circuit are well understood to those skilled in the art and need not have further description, except that the armature 45, When attracted upon the insertion of a connecting plug within a called subscribers jack, serves to ei'ace the callmg signal at 44. The operation of the supervisory apparatus 53-54 and the sig-l nals supplemental to the magnet 55 will also be well understood from the illustration without requiring further description.

In order that the link'circuit motors 19 may be prevented from stopping the arms 9-10-13 to connect the samewith a link circuit already in service, the buttons 16- 161 coperating with the arms 13-131 are multipled. In order that the arms 9-10 and 91-101 may be connected with any idle link circuit, the contact buttons 14-141 are vmultipled, as are also the but-tons 15--151.

The ground is placed upon and removed from the buttons 16--161 through-the agency of the switch element 11 and the button 12 engaging said element 11, which operation and attendant results will now be set forth.

The ground that is to be placed upon and removed from the contact buttons 16--161 is indicated at the grounded terminal of the relay 56. When the switch arm 13r (or 131, etc.) 'has encountered a button 16 (or 161, etc.) having no connecticnwith a ground, (the windings 25 and 37 having been denergized as hitherto stated)l the energization of the cut-oii relay 3 is permitted due to the denergization of the magnet 38 eiected relay 22 occasioned because of the attraction of the armature 21 in series with said magnet 22, the ground at 56 is thereupon at once 130 switch parts to their initial positions, a post.

placed in connection with the armature `switches 39440 and the switch element l1,

the exchange, so that if a magnet 56 assoc i'.V ated with a busy cord is thrown into circuit with a magnet 38 of a calling line, said magnet 38 may remainv operated without caus- 4 ing the operation of magnet 5'6. p

If the calling subscriber restores his telephone before the operator has vinserted theA connecting plug 17, or if the operator has withdrawn the lplug 17 after a completed conversation between connected subscribers, the calling subscriber then also having re- Stored his receiver, said conductor 57 will have its circuit vextended by Way of the armature 49, now released, the armature 45,

also released, the armature 50, still attracted, to the grounded battery 23, whereupon the magnet 56 will become energized to attract its armature 'and effect the engagement 'of the catch 58 in electrical connection with the armature of magnet 56 with the hook upon a grounded detent .59 preparatory to effectling the 'disengagement of said detent from the rack 30, to permit the spring- 60 to restore the` elements 5--6-11-21-39 to their normal positions. The actual disengage- `ment of the detent 59 is preferably effected by means of a fs ring 61 connected with Athe 56, to which end the cir- "gnet should be opened, in i; ,traction may not overcome 1itl spring, the spring being bf? the armature pivot and the armature ma cuit of said i] order that its the force of upon one sidel pole of the lilla-.griet upon 'the other. The

spring 61 is-l'tef'mitted to operate because the magnet again included in circuit, by reason ofltlre ground placed thereuponat 59, causing the operation of the switches 71-81, and thereby the denergization ofthe magnet 48, Whose armature 5!)v is released to open the circuitthrough.the magnet 56, whereuponthe spring 61 is free to effec-t withdrawal-of the detent 59, so that the restoring spring 60 may move itsassoc-iate 62 engaging the lhook 58 when suchrestoration is'about co," pleted to etl'ect disengagementA between said catchI 58 and the said detent 59, placin i' this apparatus in position to take parti `effecting a new connection. 'Ihe circuit'forlthe' magnet 38 just mentioned may heltiraced from the ground Aat 59, the hook 581, the armature of magnet 56,

vcalling subscriber havin the winding of magnet 38, to the grounded battery 23. After the parts 58-59 are separated, tl is circuit is opened. In case the motor 25 should step the switch contacts 5-6-11-21 overl their entire range without having effected connection of a link'circuit with the line terminals 5-6, I provide a means for effectingthe restoration of said elements, to permit a reoperation thereof. To this end, I-,preferably provide a supplemental contact button 121- tha't is not con-, nected with any arm corresponding to arm 13, but is connected by way of a switch 63 with the battery 23, whereby said battery `is connected with the switch element 11` when said element is in contact with the button 121. VVhen'the element 11 is thus connected with the battery 23, the circuit including said element contains the armature switch 40 (beca-use the element 21 is not in connection with the grounded contact, the magnet 37 vthereby being in open circuit)v and its normal contact, the armature switch 39 and its back contact, and the magnet 56. The Y manipulated his switch hook to secure this'result, thus momentarily causing aA denergization of the line relay 22 to permit of theengagement of the armature switch 39 with its. normal or back contactl the armature of magnet 56 yis thereupon operated to engagevthe hook 58 with the detent 59, whereupon the-circuitd including the magnet 56 is broken at `63 by the armature of said magnet, whereupon the spring 61 may withdraw 'the detent 59 to permit the spring 60 to restore the switch parts.'

I have hitherto stated thatbefore a cord or link circuit is to beautomatically selected,

a group ofcircuits belonging to a free operator is?" first tobe selected, this in the eine bodim'eint of the invention being described the b ittoris 20 and the conditions jointly iinposet yjupon each `of the same by-its assoeiate liaviiu" been el'ec'ted'through the agencyl/of group; of 'link or cord circuits, a grou! of occufl'iied cords occasionin'g ground upo [its huttin 20, whereas a groi'ipxif cords no ltr'igether occupied will cause its button'Z( to be freie of ground, with the results hith, 'to

stated? cludirlg the apparatus operating'ungler the laws the Wheatstone bridge, The bridge ized inlay 64whose polarized armatura-is groun"` ed, such relay being common tripa groupiiof cord or link circuits and j oin ly contro 'led in its-operation thereby. In`1 we operation ,of the ,Wheatstone a'rrangcrnelzit more gilly tobe set .foi-th, said armature `iis maint ned in the position illustrated in tile ic i i drawi ig at the left when all of the servi,

Thepreferred instriiul'ientality tlliat I emlxloy fr controlling the, applicatio 'dof nd to each button QQ-b'y 'its group of' `link or cordicircuits, is that` illustrated,A in'- of thi- Wheatstone 'circuit includes'a polarablev link circuits of a given operatorare not in use, so that the conductor 65 terminating at one end' in a contact button 20 and at the other end in a contact 'for the said armature, is under Asuch condition free of ground connection, but when all of the serviceable cords are in use, the said armature 1s swung ,to itsxalternative position into six connections, sal 8, the resistance 70 is. y*

.correspondingly a justed to permitvthe in-.

engagement with its contact, the terminal of the conductor 65, so that ground is placedl upon the contact 2,0 corresponding to 'said group of link circuits, forcing the switch l Aelements 5-6-'-],1'-,21V to continue their movementas hitherto set forth. The direcauV tion of movement ofthe Aarmature of relay '64 depends upon the direction' of current through ,said relay from the battery 23, this battery 23 being connected between two adf jacent sides-66-67 of the Vheatstone bridge clusion of eight sections 71 abreast 'before the conductor 65A is grounded throughl the armature of thefrelay 64.. As, soon as the predetermined number of sections that mayv be' included abreast is diminished, the vcuir:

rent 'through the winding of relay 64 is rel` ,versed to remove the relay armature 'from connection withthe condu'ctor 65. Arelay 7 3 'belonging to'another group of link circuits is illustrated, the armature thereof Il being shown applied to a conductor 74 (as containing the fixed resistances. The other two sides'68--69 of" the VVheatstone bridge are grounded, and,'as' the battery 23 is grounded', the v Whcatstone bridge arrangeythat/is automatically adjustable through nient that I have described is completed, for there is 'included in the side G8 resistance the agency of' the link circuits, such adjustment being effected 'as said link circuits are put into and withdrawn from service, the other side 69 containing avv resistance 70 that y is to be adjusted manually according tothe capacity o f the operator using the cord circuits vassociated with the relay 64. The resistance of the side 68 is preferably composed of a number of sections 71, each cord circuit of a group having one such section. Y The relay 48 of each link'4 circuit has an l armature switch 72 that engages a. grounded fcontact when operated by said relay to include the corresponding resistance sections 7lin ground connection. The resistances, 71 ai'e thus connected in circuit as their associate link circuits' are busy and are exeluded from circuit when .said circuits are 'restored to their normal or idle conditions. The .resistance 70 is adpistedby hand to through the rcla-y (S4 shall be so directed as to effect an application ofthe relay armature to the terminal of. conductor (35 asso-V ciated therewith. Each operator may have ten link circuits, but the resistancel may ,said called subscribers line.

the 4'serviceable link circuits corresponding to saidrela'y are occupied),=sai'd'conductor being connected with a button 20 of-a group.

A non-numerical switch is one that does not operate in response to -a series of im- .pulses' transmitted by a calling device, but4 4 y operates in response to the transmission of an impulse or upon the closure of a circuit, such-as. the closure of 'a subscribers substation circuit.

What I claim as new v'andldesire to secure by United States Letters Patent is:

ondary switches to extend the subscribers l line toone of said connecting circuits, and means. for then extending the connection to v2. A telephone system'inclu'ding a Sub#A`VY scribe'rs telephone line,A af primary switch for said line, a secondary switchaccessible to said primary switch, trunking means accessible to said secondary switch, and inechaf 'uism for said primary and secondary 'determine the time at which thef currentv switches responsive to the removal of a receiver at the substation of said telephone "line to connect said telephone line with Vsaid be so adjusted that the. moment six,for'

example, of the resistance sections 7l are connected to ground, the-armature of relay 64 will be connected with conductor 65, so that the selecting mechanism of the subscriber calling will pass the button 2O connected with conductor G5 thus grounded, until the element 21 of said selecting mechanism will .engage a button 2() from' which the ground has been removed. Thus` the operator having the relay 64 cannot attend to more than six connections at a time. if

trunking means. 115 A telephone system including a calling and a called subscribei"s line, connecting circuits, individual primary and non-numeri cal ,secondary -trun king switches, a line relay individual to the calling Subscribers line 126 for.. initiating the operation of one of said primary and one ot' said secondary switches for coni'iecting-said calling subscribers line Yto an idlcone of said connecting circuits,

and means for then extending the connection to said called subscribel"s line'.

' -4f. A telephonev system including a calling and a called subscribers line, trunk lines,

. non-numerical primary and secondary trunkthe capacit-y 'of the operator is greater than.'

ing switches, the primary switches being in- 130 so- 1. A ytelephone system including a calling l f Ma" dividual to the subscribers lines, a line relay individual to the calling subscribers line and controlled over the two sides of said line 1n series for causing the successive oper- 5 ation of one of said primary and one of said' secondary switches to extend a call from the calling subscribers line to an idle one of said trunk circuits, and means for then connecting with and signaling the called'subscribers line.

5. A telephone system including subscribers telephone lines, grouiis of primary switches for said lines, secondary switches accessible to said primary switches, a group Aof y connecting circuits accessible to said secondai'y switches, and lmeans controlled over tlietwo sides of a calling'line in series to operate one of said primary switches and one ot said secondary switches to connect to one of said v connecting circuits, and operator controlled means for extending connection from said connecting circuit to a called one of said lines. M

6. The combination with a selector carrying-groups ot' line terminals, of a coperating movable contact 'therefor adapted to' test said lilies -by groups', and nie'ai'is, actuated 1n case all the lines in a tested groupare unselectable, for advancing,r said movable con- 0 tact in a siiiglestep to the next group.

7; The combination with groups of lines, of a selector carrying terminals for said groups, a test contact foreach group of line terminals, a source of current associated with.

. eacliwgroup,'a. conductor connecting said sourde with the test contact of each group, and irieans for Vary-nig' the continuity ot' said conductor according to the seleetability or non-'selei'll'ability-of the line tei'iiiinals int'liat ,s0 'group H..I`he minliination' with a number of groups ot'k truuk line teriiiiiials,.ol selective apparatus t'oi connecting therewith adapted to test said groups ot tei-initials one after v 45. the other to'select a group containiiigan idle trunk line. i I

it. 'l`he coinbiiiatiijin with groups of trunk lines, ot a .selector carrying teiiiilnals tor saidgi-oups` a test contact t'or each group'ot'I trunk linel terminals, a sourceyot busy current associ-ated .with4 each group, and a conductor connecting said source willi the test contact olf` said group, the -ontiiiuityot' sau-l conduit.--`

' tor heilig completed when all the lilies in said-group are busy.

10. ',l`he"coiiibination with a selector carry-- ing groups ot truiik line teriiiiii-als, of a contart ai'in tl'ieret'or adapted to test said ti'iiiilc lines h e'rou is and iiieans actuated iii-case y all the truuk lines iii a testedjgioi-ip are i busy, for,a'di'aiiciiigr said ariii iii itsiiigle step to the next group.

ll. The coiiibinat ion with a Selector carrying groups ot line teiiiiiiials,ol a cooperating nio vable contact therefor adaptedto test said rality offsubscribcrs #telephone lines,

-iutoi'iiatic triinlnng switch. individual t0. ,each of said subscribers lines, secondary -said lines to an idle one ai said trunk lines by groups, and means, actuated incase.

all the lines in a tested group are unselectable, for advancin,9I said movable contact in a single step to the next group.

12. A telephoi'ie system including a subscribers telephone line, an automatic switch individual thereto,- a' secondary automatic trunking switch accessible to'said first auto" matic switch, trunk lines accessible toA said secondary automatiqswitch, and ,means controlled by the calling subscriberlover the two sides of the subscriber-slime:in series for f operating said automatic iswitches"` to extend al connection from sai Subscifibers line to an idle one of said trunk circuits."`

-18.VA telephone system lincluding a plurality-ot' subscribers telephoneJ lines, autoiiiatic trunking switches-one for each of Said lines, secondary `tf1-linking switches accessible ,tol isaid first trunkmg switches,

oups. of

link circuits accessible to said secondary4 switches, and means controlled by a calling one of saidsubseribers over the two sides'of the' subscribers line 1n lseries for operating the switch individual to the subscribersline l and one of said secondary trunking switches -fo'connect said subscribers line to an idle.

one of. said link circuits.

14.l A ,telephone systeiii including a plulrality ot' subscribers telephone lines, aut

matic trunking switches one'for each said lines, secondary trunki-ng switches accessible to said first. trunking switches,

circuits,'and iiieans for extending a con-- iiection from saidliuk circuit to' a. called one ot' said subscribers lines. 15. telephone system including a plutrunkiug switches. accessible to said viirst truiili'iiig switches, trunk circuitslaccessible to said secondary.trunking switches, subscriber controlled iiieans for successively operating his individual trunk sii'itcli.aitd

one of said .secondary truiil-:ing switches to extend a connection froiii the calling one of circuits, and iiieans for then completing thel connection to a ycalled one of said lines.

toiiiatic truiikiiig switch'individual to said subseriliers line, a secondary Inon nuiiierical lt. A telephone systeiii includinga sub-` scrilicr`s telephone line, a iioii-iiiiiiierical autruiikiii'url switch accessil'ile toA said tirstl truiiking switch, wipers for said secondary switclifgroups of trunk circuits accessible ing and a called subscribers telephone line,

17. A telephone system including a .sub-

Vscribers telephone ,line a lnon-numerical automatic trunking l'switch individual to said subscribers line, a secondary non-numerical trunking switch accessible to said first trunking switch, wipers or s aid secondary Switch, groups of trunk circuits accessible to the wipers of said secondary? switch, and subscriber controlled means foip successively operating said switches to eX- tend av connection from said subscribers line to an idle one of said trunking circuits, said means being controlled over two sides of the subscribers line 4in series.

18. A telephone system including a subscribers telephone line, an lindividual nonnumerical trunking switch therefor, a second-ary non-numerical trunking switch terminating in bank contacts of said first trunking switch, a plurality of trunk circuits terminating in bank contacts of said secondary switch, and subscriber controlled means-for operating said switches to extend a connection from said. subscribers line to an idle one of `said trunk circuits.

19,. vA telephone system including a calla non-numerical trunking switch individual to said callinggsubscribers line, a secondary non-numerical trunking switch accessible to said -first trunking switch, trunk lines accessible to said secondary Switch, ,subscriber controlled means for successively operating said switches to extend a connection from the calling subscri'bers line to. an idle one of said trunk circuits, and means for extending, aconnection from the selected trunk circuit to the said called subscribers line.-

20. 'A telephone system including aplurality of,subscribe'rs telephone lines, a nonnumerical progressively movable tr'unking switch for each of said subscribersftelephone lines, secondary non-numerical trunking switches't'erminating in bank cor'itacts of said iirst trunking switches, and accessi ,ble "thereto,.trunk circuits terminatingl in ,has

bank contacts of said secondary trunkingswitches and accessible thereto, and means controlled by a calling one ofgsaid sub,

scribersfor,opepating his individual trunk-- ing switch and one of said secondary switches to extend aconnection from the subscribers telephone line to an idleoiie oty said trunk' circuits. y ,i

21. A telephone system including'a plurality of subscribers 'telephone' lines, a non-numerical progressively mova'bl'e trunk-` ing switch for cach of said subscribers telefy phonelines, secondary non-numerical trunky l ing a group of conductors, groups of autoing switches terminating infbank contacts j ing. algroup of said first trunking .switches and accessible thereto, trunk circuits terminating in bank contacts of said Ysecondary trunking switches and accessible thereto', means controlled by a calling oneJof said subscribers for operating his individual triinking-switch and one of said secondary switches to' extend v l I -a connection from the subscribers telephone line to `an idle one of said trunk circuits, and means for then extending the connection from the selected trunk circuit to a called one ofsaid subscribers lines 22. A telephone system including a tele phone line, selective switch mechanism, a A

plurality of operators cord circuits having terminals associated with said switch mechanism arranged in groups, means outside of said switch mechanism for rendering some of said groups busy, means for operating ,said switchmeclianism on initiation of'a call. over -said telephone line` whereby said.

switch mechanism automatically tests said cord circuits by groups avoiding -busy groups,and means for causing said switch matic switch passive contac.ts,.each group" having contacts forming terminals of .said .l conductora, means associatedVwith each ygroup of passive-contacts for automatically selecting the passive contact ofa'n 'idle one of said conductors, means for selecting said group of conductors, and means responsive tothe selectionof;v all the conductorsin the lgroup to control r,said

24'. -Atelephone exc ofconductors,l groups of automatic switc i'ng contacts forming',t terminals of said conductors, means associated with each group of passive 'contacts for automatically selecting. fthe passive contact of an idle on'e'of` said conductors, meansfor selecting said group of conductors, and means responsive to the to cau'sethe selecting means to move by lthat group selecting means; lange system comprisv y i passivecontacts, each group hav- "selection of all the conductors in the 'group iis ing a group of conductors, groivips ofautohaving contacts forming terminals of said conductors, meanslg'associated with each ,group of passive contacts for automatically selecting the passive contact of an .idle one. of rsaid conductor-skincans for selecting said:

'matic switch passive contacts, eaclngroup j 'piaci V for said' group selecting means, an electro magnet for each conductor, means for energizin each conductors magnet upon the selection of that conductor, and means responsive to the energization vof the magnets of all the conductors to actuate said switch.

QXL-In a telephone system, a subscribers ating magnet insaid switch normally connected to said dine, a cut-off relay, and means for energizing 'said cut-off relay to disconnect said operating magnet from the 'line when said line is calling or is being line, an automatic switch connected to'said line provided with a Contact maker ,capable of assuming a plurality of selective positions, trunk lines for selection by said automatic switch, a second subscribers line, means including said automatic switch for extending a call from said first to said second subscribers line means for 'eXtendin a call from said second to said rst subscribers line, operating means for said switch bridged across said line, and a magnet or'disconnecting said operating means from across the line when said first connection is established, said magnet also being operable to disconnect said operating means from across'the line when said second connection is established. A

28, A telephone system ineluding'a subscribers line, an automatic switch individual, thereto, a second subscribers llne, means 1n' cluding said individual switch for extending a connection from said-first subscribers iine to said second subscribers line, means Jfor extending a connection :from said sec'- ond subscribers line to said first subscribers line, an operating relay for said switch connected to said Irst line, and a cut-o relay for disconnecting said operating relay from said first subscribers line when said switchis used to extend the connection to the second subscribers line, said cut-0E relay also being operable to disconnect said operating relay from said subscribers line when the second subscribers line is connected to the said i'irst subscribers line.

29. in a telephone system, a subscribers line, a progressively movable non-numerical switch individual to said line for extending connection therefrom, means for establishing a connection to said line, an operscribers line,

called. y

30. A telephone system including a suba progressively movable switch individual to said line, means for extending a connection from said subscribers lineincluding said switch, an operating magnet for said switch normally connected to said subscribers line, a cut-off relay, means ,for energizing said cut-ofi' relay to disconnect said operating magnet from the sub'sc'ribers line when said switchl is operated for calling purposes, and means for ener izingfsaid cut-od relay to disconnect sai operating ma et from the subscribers line when sain called line.

31. A telephone line having before it mul-` tiple terminals of link circuits,- said link circuits having before them multiple termi- Vnals of other circuits, and non-numerical switch mechanism for said lines and link circuits adapted to extend said line by means of a selected idle link circuit terminal and a selected idle terminal of one of said other circuits.

32. A. telephone system including a subscribers telephone line, a primary .switch for said line, a secondary switch accessibleto said primary switch, o erators answering means accessible to sai secondary switch, and mechanism for said primary and secondary switches responsive to the removal of a receiver at the substation of said telephone line` to connect said telephone line with said answering means.

33. A telephone line and automatic switch.- ing means provided with a contact maker capable of assuming a plurality' of selective positions individual to said line, an electromagnet individual to said telephone line' operating responsive to a control over said V,line to disconnect said automatic switch,

and means for controlling said magnet to disconnect said automatic switch when connection is made to -said line as va called line. Signed by me at Scarsdale, in the county of Westchester, and State of New York, this 16th day of January, 1918.

. FRANCIS W. DUNBAR.

line is used as av

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