US1558812A - Automatic telephone system - Google Patents

Description

Oct. 27, 192.5.

E. JACQBSEN A AUTOMATIC TELEPHONE SYSTEM origina; E11 Jui 11;*1917 bbs/sri Emi@ yl Patented Oct.- 27, 1925.

UNITED STATES 'PATENT OFFICE.

EMIL JAoOBsEN, or CHICAGO, ILLINOIS, AssIGNOR To AUTOMATIC ELECTRIC, OOM- PANY, or CHICAGO, ILLINOIS, A CORPORATION or ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application led June 11, 1917, Serial No.i174,0l13. Renewed June 22, 1925. I

To (/Z Hiom t may concern.'

Be it known that I, EMILMJACOBSEN, a citizen ot' the United States-ot America,- andresident. ot Chicago, Cook County, Illinois, have invented certain new and useful Improvements inAutomatic Telephone Systems, Ot whi-ch the following is a specification.

My invention vrelates in general to automatic telephone systems, and more particularly to those automatic systems which are commonly known as two wire systems, in

. which automatic switches at the exchange are controllable over the two sides of a calling line in series. Certain vfeatures of the invention, however, will no doubt be found to be of utility in systems ot other typey More specifically, my invention has for its principal object t-he provision of an iinproved connector switch having automatic trunk selecting functions, a connector of this type being ivell adapted for connecting with trunk lines extending to a private branch exchange; and being commonly known as a rotary connector. One of the details of improvement consists in the omission of the usual side switch, the circuit changes which were formerly performed by this mechanism being in my improved switch performed entirely by relays. A,ln addition to the foregoing and other circuit improvements having to do with the Operation ot the connector switch, my invention is also concerned with supervisory circuits,

some of which are provided to enable an' attendant at the main. exchange to supervise the operation of the 'connector switches, while others are for the purpose of operating signals before a private branch exchange operator. I

All the foregoing improvements, together with others not now specifically mentioned, vwill be fully explained hereinafter, refer- `ence being had to the accompanying draw .glhe drawings comprising Figs. 1 and 2, when arranged in order with the corre- Aspondinglines at the ends thereof in alignment, show diagrammatically a complete `circuit connection betweena calling substation A in the main exchange and the called substation A in a branch exchange subsidiary thereto. This connection-has been established through the medium of the in,- dividual line switch C. the first selectorE',

the second selector F, the rot-ary connector Il., the trunk line 200-201 extending from the main exchange to the branch exchance and terminating at the latter point in tile` British patent to Martin #1419 of 1910. As represented herein it comprises essentially the receiver 2, transmitter 3, switch hook 4. ringer 5, and condenser 6. Being an automatic substation there is also pro-\ vided a pair ot' impulse springs 7 and 8 which may be .controlled by an impulse 4wheel 9 through the medium of a finger hole dial (not shown),

The line conductors 11 and 12 of the substation j A extend to the main exchange where they terminate in the individual line switch C. rlhe line switch C is ot the general type of line switch shown in the British patent to .lames #-26.301 M1906; being, however. ot the particular type shown in U. S. Letters Patent #1,078,690, granted January 17, .1912, to Frank Newfortli. Through the medium of the lineswitch C, the line ot substation A when calling is given access to a plurality of trunk lines eX- tending to selector switches. l

The line switch C and av lurality y of similar line switches are contro led in their trunk selecting operations by 'means of a master switch D. This master switch is of the general type of masterswitch'disclosed in the above mentioned British patent to James #26,301 of 1906; being, however, more nearly ot the particular type disclosed in the British patent to Martin #1419 of 1910, also previously `referred to. As is well known, the function of the master switch is toA maintain the plungers of all the idle line switches which it controls in position before the terminals lof 'an idle trunk line.

one'of the' trunk lines; to whaha@ iin@- switch C has access is'shown extending to the iirst selector E. The selector E may be of the general type of selector switch disclosed in U. S. Letters Patent No. 815,321, granted March 31, 1906 to Keith, Erickson & Erickson. The side switch and the private magnet are omitted, however, and the circuits are modified in .accordance with the two wire system of control.

The second selector F is in all respects similar to the first selector E.

,The connector H may be of the general type of `connector switch disclosed in U. S. Letters Patent No. 815,176, giZant d March 13, 1906, to Keith, Erickson and rickson. As before mentioned, however, the side switch and private magnet of the connector switch are omitted and the circuits are modified in accordance with the two wire system of control and also in order to accomplish the objects of my invention as will be'explained fully hereafter. The wiper construction of connector H, the Wiring of its bank contacts, and the grouping of the trunk lines terminating therein is similar to the arrangement shown and described in thcl U. S. Letters Patent No. 1,312,558, granted August 12, 1919,` to Talbot G. Martin. It may be stated that each bank level comprises ten contact sets in which terminate ten trunk lines, which latter may be divided into any convenient number of groups. There may likewise be any desired number of trunk lines, from one to ten, ineach group. vEach contact `set comprises four contacts, which are the usual line, private or test contacts, and an. extra test contact. This extra test contact is deadexcept in the case ogf the contact' sets which are associated withthe last trunk lines of the different groups, the two test contacts associated with the last trunk line of each group being connected together. The connector H -is provided with Ithe usual line and private wipers and in addition with a fourth wiper which is adapted to cooperate with the extra test contacts above mentioned.

f One of the trunk lines accessible to the connector `H Ais the trunk line 200-201, which is assumed to be the last trunk line iny`some particular' group.. Theline condrctors 200 and 201 terminate in the line contacts 195 and 198. The contact 197 is the regular test contact, while the contact 196 is the extra test contact. Since as al- Y ready stated. the trunk line shown is assumed to be the last trunk line in the group, the contacts 196 and 197 are connected together.

The trunlcline shown is a two-way trunk line, that is, itis adapted to handle calls either to or from .the private branch. ex-

change. The latter class\of connections are taken" care of by the individual line switch C which is in all respects similar to the line switch C already described. Atthe private branch exchange the trunk line ,200-201 terminates in the jack J and is also provided with aline signal lamp L, the

relays 202, 203 and 204, and the calling deing and calling plugs connected by condensers, the supervisory lamps L3 and L4 which are controlled, respectively, by the relays 220 and 221, the ringing key K2, and the combined listening and ringing key K. This cord circuit may be used either for connecting two of the branch exchange substations such as the substation A Fig. 1; or for connecting one of these bra/rich substations with the trunk line extending to the main exchange.

lVhile I have shown throughout the drawings a plurality of batteries it is to be understood that there is preferably'but one battery having its positive pole grounded, or rather there may be two batteries, one in the main exchange and the other in the branch. In ordernot to encumber the drawings separate reference characters have'not been applied to the different batteries and it will be understood that when a circuit is traced to battery it extends tothe live or ungrounded polevof the central 'or common` battery. Associated with connector H, I have shown a ringing equipment R and a busy signalling machine Q.. This apparatus may be of the usual type such as is .found in well`known telephone systems. There are also shown two supervisory signal lamps L and L which are preferably common to the group of connectors of which the connector H is one. The operation and function of these' lamps will be described later.`

Having briefly described they apparatus involved, I` will` now 'proceed to explain more in. detail the operation of the same. For this purpose it will be assumed that the subscriber at substation-A desires to obtain connection with the subscriber at substation A', this being the circuit connection shown in the drawing. When the receiver is removed at substation A 6 initiate the call an energizing circuit lis completed over the line conductors 11 a-nd 12 for the line relay14 of the line switch C. Upon 'attracting its armature the line relay 14 closes a circuit for the, pull-in winding 18. Upon energizing, the pull-in winding operates both the plunger arm 15 and the cut-ofi' armature 16; the former through the medium of its plunger not shown) forcing' the bank springs 30 to 33, inclusive,

respectively, withl contacts 34 to 37, inclusive; and the latter disconnecting the line` engagement of bank springs 30 and 33 with into engagement,

- may betraced as follows:

aussie p contacts 3l and 37, respectively, the line conductors 11 and 12 are extended through normally closed contacts of the switching relay- `substation A, and upon attracting its armature closes the usual energizing circuit for the slowl acting'release relay 51. Upon energizing in turn, the release relay closes a holding circuit for the line switch C which round at G', working contact of armature and the said armature.conductor 61, contact 35, spring 31, andthe holding winding 17 to battery. Since the line relay 14 .is slow acting it re tains its armature attracted in order to maintain the pull-in winding 18 energized until after the above holding circuit is completed. A branch of th'e holding circuit extends by Y way of conductor 2Omultiple-test'contacts in the banks of connector switches having access to the line of substation A, where by a ground potential on these test contacts the said line is made busy. By the engagement of bank spring 32 with contact 36 the master switchD is operated in the usual `and well known manner to advance the plungers of all the remaining idlel line 'switches into position before the next idle trunk line.

The foregoing operations have occurred in response to the removal of the receiver at substation A. The calling subscriber may now operate his calling device in accordance with the first digit of the desired number, thereby producing a series of interruptions in the circuit of the line relay of the se lector E. The line relay 50 is accordingly deenergized a number of times and at each deenergization transmits `an impulse from ground G2 through the slow acting relay 52 and the vertical magnet in series to battery. In response to' these impulses the vertical magnet, operates to raise the switch shaft step by step until the wipers 70, 71 and 72 arrive at the horizontal level of bank contacts corresponding to the first digit of l'the called number. l The slow acting relay 52 isenergized in series with the vertical magnet and retains its armature attracted during the series of impulses. Upon the firstupward movement of the shaft, the oi normal springs 59 are closed,thereby complet ing an,initial energizing circuit for relay 53 which extends as follows: .ground at G', working contacts of armature 60, the armature -of relay 52 and its working contact,

off normal springs 59, and the winding of the said relay53 to battery.` vUpon 'energizi-ng, relay 53 locks itself independent of relay 52 at its upper armature, and at its lower armature prepares a circuit for the rotary magnet 54, which, however, is held open during thevertical movement of the switch by `the'relay 52. lAt this point it should be mentioned that by the closure of the off normal springs 59 the switching relay 57 andthe relay 53 were connected in se- 'i ries. But since the junction of these two relays has already been grounded, as explained, the relay 57 is short circuited and remains inoperative for the present.

When the slow acting relay 52 deener-I gizes at the end of the series of impulses it completes at its back contact the circuit of the rotary magnet 54. Upon energizmg, the rotary magnet operates to rotate the wipers 70, 71. and 72 into engagement with the first set of contacts in the horizontal level opposite which they were raised. Near the end of its stroke the rotary magnet opens lthe circuit connectingl relays "57 and 53 at its lower interrupter contact and at its upper interrupter contact opens the locking circuit of the last mentioned relay 53. Upon deenergizing, relay 53 breaks a circuit of the rotary magnet 54,* -which accordingly reti-acts its armature-toagain close its interrupter contacts. The operation now depends upon whether'the trunk line the terminals of which are now engaged by the switch wipers is busy or not. If this trunk line is busy` the test terminal with which the test or private wiper 71 is injengagement will have ground potential upon it, which ground potential will serve to maintain the switching relay 57 short-circuited and to again energize relay 53; The rotary magnetA circuit is therefore again completed and the same cycle of operations is repeated, whereby the yswitch wipers are advanced into engagement the next set of bank contacts. It will be'seen then that the relay 53 will operate as an interrupter orsteps ping relay to advance the switch wipers step by step through the medium of the rotary magnet as long as the test wiper 71 continues to engage busy or grounded test contacts. When Aan idle truuk line is reached, however, the test wiper 71 will find no ground potential upon theI associated test` short circuited, it at once energizesin series with the rela-y 53. Relay 57 is of sufficiently high resistance to prevent the operation of relay 53. Upon energizing,-relay 57 opens at its lower armature a contact i-n the circuit of the release magnet 56 to guard against the release of the switch upon the deenergization of relays 50 and 51;` shifts at itsupper armature the private wiper 71 from its upper to its lower terminal.; and at its two inner armatures disconnects the incoming line conductors from the windings of the line relay 50 Iand extends them instead by way offwipers and 72, bank contacts 73 and 75 and normally closed contacts of switching relay 87 to the double wound line relay 85 of the second selector F;

Immediately following the extension of the calling line as above described the line relay 85 is energized over the two sides of the calling line in series land upon attracting its armature closes the usual energizing circuit for the slow acting release relay 86. Upon attracting its armature relay 86 completes a holding circuit extending back to the selector E and line switch C over the following path: ground at G4, working contact of armature 88 and the said armature. conductor 89, bank contact 74, wiper 71, and the upper armature of relay 57 and its working Icontact to junction point 65; Where the circuit divides, one branch extending by way of the winding 57 and the winding of relay 53 to battery, while the'other branch extends over a previously traced path through thev holding windin V17 .of line switch C to battery. It is to ge understood that the above described Iholding circuit is completed before the slow acting release relay 51 of`selector E has had time to deenergize.

The calling subscriber may now operate his calling device in accordance with the second digit `of the called number, thereby producing a series of interruptions in the circuit of the line relay 85 of the selector F. The selector F is now` operated in precisely the same manner that selector E was operated, to select in 'accordance with the d1git` called the required roup of connector switches and to therea er automatically select a trunk line extending to an idle con.-

nector in the selected group.` .Since these operations have already been described in the case of selector E yit will be unnecessary to repeat the explanation. vIt will be sufficient to say thatl when the wipers 90, 91

and 92 'of the selector F arrive at the set of bank contacts in which the selected idle trunk line terminates, assumed .to be the bank contacts 93, 94 'and 95, the rotation is stopped and the switching relay 87is energized in the usual manner to extend the line conductors by way of wipers 90 and 92, bank contacts 93 and 95, and normally closed contacts of the answering bridgey relay110 'to the double wound ,line relay 100 of the connector H.

The line relay 100 is accordingly energized over the calling vsubscribers loop and upon attracting its .armature ,closes the circuit of the slow acting release relay'101.

Upon energizing in turn, the relay 101 completes a holding circuit for the selector F and the other switches which may be traced as follows: ground at Gr,l working contact of armature 114 and the vsaid armature, conductor 160, bank contact 94, wiper 91, andI working contact to junction point 96; where the circuit divides, one branch extending by way of the winding of relay 87 and the winding of relay 97 to battery, and the other branch extending back to the selector E and the line switch C over a .path previously traced.

The calling subscriber may now operate his calling device in accordance with the third digit of the called number, thereby producing 4a series of interruptions in the circuit of the line relay 100 'of the connector H. The line relay therefpre isV dcenergized a number of times and at each deencrgization transmits an impulse through the 'slow acting relay 102 and the ,vertical magnet 112 as followszground at G", armature 113 and cated contacts which constitute terminals of trunk lines extending to 'the desired private branch exchange. The slow acting relay 102 is energized in. series with the vertical magnet and retains its 'armature 116 attracted duringthe series of impulses, thereby preventing the opening ofv the vertical f magnet circuit by the shifting of the'oi' normal springs, which operation occurs as soon as the shaft leaves its normal position.

The .calling subscriber may now operate his calling device in accordance with the final digit in the called number, which digit it should be mentioned, 'will corres ond to the position of the'contact set whic is associated with the first trunk line of the dc sired group. For example, if the first trunk line of the group of trunk lines extending to the wanted branch exchange terminates yin the fourth contact set in the selected level, then the final digit to be called will be the digit .4. When the final digit is called a series of interruptions is again produced in the circuit ofthe line relay 100. Now, however, the olf normal springs 117 to 121, in-

clusive, being in the position: shown in the drawing, and the slow actin relay 102 havving deenergized, the line r'e ay transmits a series of impulses to the rotary magnet 109 over the following path: ground at G7, armature 113 and its resting contact, armature 115 and its working contact, off normaL springs 121 and 120, armature 116 and its resting contact, resting contact of armature 132 and the said armature, armature 129.

tary magnet 109 to battery. In response to branch vof the rotary magnet circuit extendsfrom -junctioli'point 162 through the windthese impulsesthe rotary magnet 109 is operated tobrotate the wipers 191 to 194, in-

clusive, into engagement with the contact set` in which terminates the first-trunk line of the selectedgroup.` It will be noted that a ing of relay 106 4to battery. It follows that i V relay 106 will beenergized in parallel with lQLthe rotary .m'agnetA-andsince,this relay yis the Isaid armature 135, relay 106 closes a" rcircuitfor relay 107 abs-follows: ground at I G8, working contact of Aarmature 114 and the said armature, conductor 160, armature- 126 audits restingl contact, armature 135 and .its working Contact,- and the upper winding of relay 107 .to battery. Uponenergizing, relay 107 establishes a locking circuit for itself which may be traced as follows: ground at G", Working contacts of armature 114conductor 161, armature 141 and its resting contact,armature 139 and its working contact, and the upper winding of thesaid relay 107 to battery'. -As an additional result of its energization, relay 107 prepares a test circuit at its armature 136 which includes the. testwiper 192 and the winding of the test relay 104. Thiscircuit is heldopen, however, during the rotationof the switch by the relay 106 at lits armature 133 and since moreover itcan be of no cfcct except when all the trunk lines of the select,-

-. edgroup are busy .it may be neglected for the present. A` further result of the energization of relay 107 is the preparation of a circuit for' the stepping relay 105 at its i armature 140. VThis circuit also is held open during-the rotation ofthe -switch at the armature 134 of relay 106. 'lhe operation of the line reversing armatures 137 and 138 at this time is of no particular consequence.

At the end of the final series of impulses relay 106 deenergizes, thereby closing at its armatures 134 and 135, respectively, circuits for thestepping relay' 105 and the upper Windingoftheswitching relay 108. The operation now depends upon whether the first trunk line the contacts of which are now engaged by the wipers 191 to 194, in elusive, is busy or not. It has been statedl before that the trunk line shown in the drawing is the last trunk" line of the group to which it belongs and we Wlll thereforeassume in this explanation that the remaining trunk lineslare busy. rl`his being the case the test- 'contact with which the private or test wiper 193- is now in engagement will have a ground potential upon it. AS a' result of this ground potential the up er winding ofrclay 108 is short oircuited, t is relay ,being thereby `prevented from energlzing, and a circuit is completed for the stepping relay 105 as followsz, grounded test contact, private wiper 193, resting contact of armature 134 and the said armature,L

resting contact of armature 163 and the said armature,- interrupten contact of thel rotary magnet 109, working contact of" i 'armature 140 and the said armature, and.'` the windlng of relay 105 to battery. Upon '80 following path: ground at G9, working conenergizing, relay 105 locks itself over the tacts of armature 114, conductor. 11,61, armature 141' and its resting Contact, vvvgorking 'cont-act'of armature 131 and ythe said larmature, resting contact of armature 163l and the said armature, i'nterrupter contact of Kthe rotary magnet 109', working contact of the armature 140 and the said armature,

and the winding of said relay 105 to battery; u

At the same time relay 105 completes a new energizingl circuit, for the rotary magnet 109 `which may be traced as a', branchof its locking circuit above described as, follows: junction point 166,*Working contact of armature 132 and the said armature, armature` 129 and its restmg contact, armas ture 144.and its resting contact, andthewinding of the rotarv magnet to battery. In response to theclosure of its circuit the Arotary magnet is energized and the .wipers 191 to 194,'inclusive, are thereby advanced into engagement with the, contact set associated with thenext trunk line.l It will be vseen that when the rotary ma et is operated as above described the s ow acting relay 106 is not energized in parallel there.`

"with ",Near'the end of its stroke the rotary magnet opens its interrupter contact, thereby breaking the locking circuit of *relay 105, which relay is accordingly deenergized to 1n turn break `the circuit of the rotary magnet. l The rotary magnet therefore Ris deenergized and agaln closes its interrupter contact. second trunk line also is busy, the test wiper- Since kit has been assumed that the 193 will find a ground potential on the test' contact associated with that trunk line, resulting in the continued short circ'uiting of the switching 4relay 108 Vand the reenergization of the steppingl relay 105. When relay 105 energizes again the entire cycle of operation just described is repeated, whereby the switch wipers are advanced another step.

Thus it will be seen that as long as .the prlvate wiper 193 continues tov engage grounded or busy test contacts, the rotation of vthe switch will continue under the control of out 'that the upper winding of relay 108 is not only short circuited by ground upon bushy test contacts but also, whenever the stepping relay 105 is energized, by ground from GrG over a branch of the previously described locking circuit of the said stepping relay.. This branch includes the armature 131 of relay 105 and the armature 134 of rela 106.

l e have assumed thatthe last trunk line of the group, being the one shown in the drawing, was idle when the call was made. It follows then that when the test wiper 193 arrives at test contact 197 it will find no ground potential. An energizing circuit istherefore at once established, while relay 105 and the rotary magnet 109 are still energized, for the cut off Winding 17 of the line switch C. This circuit mayl be traced as follows: ground at G,work1ng contacts of armature 114, conductor 161, ar-

mat-ure 141 and its' resting contact, working .contact of armature 131 and the said armature, armature 134 and its' resting contact, test Wiper ,193, ltest Contact 197, and the holding winding 17 to. battery. By. the

1 fore mentioned the above circuit serves also y so' -to short circuit the upper Winding of relay 108 in order to prevent .its energization after the deenergization of the stepping relay 105. When this operation occurs the holding winding 17 is maintained `ener+ gized for -a brief interval over the following circuit: ground at G left handworking contact ofarmat-ure 114 and the said armature, conductor 160, armature'126 and its resting contact, armature 135 I and its resting contact, upper' winding of relay 108, test Wiper 193, test contact 197,. and the winding 17 to battery. The relay 108 is energized when the above circuit conditions are established, not only by reason of the current which .liows through the windin of-the winding 17 of the line switch but algo because of current ow in twobranch .circuits which extend from Wipers 193 and 192, respectively, through the windings of relays' 105- and 104.l The circuit throughthe former relay 105'has already been traced while that through the test relay 104 will be described in detail during the descri tion of thev operation ofl calling 'a busy llne.l Itl should be mentioned, however, that the test relay 104 is of high resistance, is given a stii adjustment, and because of effect of the lower iresistance 105, oes .not energize.v As to relay 104) isopened. At the resting contact ofv armature `=`1'41. the locking circuitof relay 107 is broken, `thereby permitting the deenergization of this relay. Upon deenergizing,\relay 107 breaks the ciacuit of the test relay 104 at anotherpoint (armature 136) and at armature 140 opens the energizing circuit of the stepping relay 105. Returning n oW to the relay 108, by the complete attraction of'its armature' 141, this relay completes anew energizing circuit for vthe hold- 1n r winding 17 whichmay be traced as follows: ground at G?, working contacts of armature 114, conductor 161, armature 141 wiper 193, test contact 197 and the holding `winding 17 to battery. A branch of the above circuit extends' by4 way of the armature 141, its left hand workin ycontact and the lower winding of the said, relay 108 to audits right hand working contact, test battery, thereby serving to lock'relay 108 kin energized position. l

A still further result of the enerofizati'on of relay 108 is the closure of a signalling circuit extending over the trunk line'to the branch exchange which may be traced as follows: ground at G8, generator Gen, working contact of ringing interrupter R, resting denser 205, resting contact of armature-206 and the said armature, right hand Winding of ring down locking relay 203, condenser when an idle contact set is reached until contact of armature 124 and the said arma- .100

206', conductor 200, bank contact 195, Wiper 191, Working contact of armature 142 and the'said armature, resting contact of armature 137 and the said armature, armature 123 and its restin contact, upper Winding of the r-ringing cut otery -to ground G". Ringing current from relay 103 and the central batgenerator Gen is thus projected out over the l trunk conductors 200 and 201 to operate the ring down relay 203 at the operators position in the branch exchange. Uponx attractving its armature, relay 203 completes a locking circuit;l foritseli.which includes the line lamp L2. By the. illumination of lthe lamp y -L2 the operator is advised that a call has been received." vShe will thereforeselect an idle cordcircuit, assumed/in this case to be the cord circuit O, and insert the answering plug thereof in the jack J. By the 'insertion of the plu' in the jack a circuit -is completed inl an o vious manner for thefcut oil' relay v204; By the energiz'ation of the relay 204,

' and the booster batterysubstituted therefor.'

The ring cut 0H relay 103 is so adjusted that it will operate on the current from generator Gen and the exchange battery in series when the direct current bridge through the polarized relay 202 is closed at the branch exchange, or on current from the exchange battery and the booster in series under the same condition; but it will not operate from-gen-` erator current alone when the condensers associated with the trunk `line at thev branch exchange are included-in the bridge thereat.

When the operator'responds and the relay Y 202 is bridged across the trunk line the relay 1,03 is energized at once/ irrespectivel of the position of the inter-ru /ter apparatus R; and locks itself overthe following circuitzg'round at G", working contacts of armature 114, Working contact o f armature 122 and the said armature and the lower winding of relay 103 to-battery. A branch of the above-circuit supplies ground to the lower winding of the back bridge or' reversing relay 110. The

lower Windino of the relay 110 is connected as shown ratther than to groundL direct'in order that the calling subscriber may 'detect the operation of the ringin apparatus by the tone which he gets by in uction between the windings of relay 103. To roceed, byattracting' its armatures 123 and) 124, relay 103 disconnects its upper winding and the lead to the interrupter apparatus R and fat the working contacts .of these armatures finally comp etes the talking circuit through the connector H. The answering bridge relay` 110 is now energized in series with the polarizedrelayl 202 at the branch exchange, the circuit being traceable Without diiliculty over the heavy line conductors, and upon attracting its armatures 146 and 147 reverses the incoming line conductors as re ards their connections to thewindings of t e line relay 100.7' This-causes a reversal of current in the calling line which-may operate ameter (not shown) in the usual and Well known manner. The attraction of armatures 148 and 149 of relay 110 is of no efiect but the circuits controlled by these armatures will *be describediater.

At the -branch exchange, the operator will `now throw her listening key K. and upon ascertaining of the calling subscriber v the name of the` party wanted at the branch exchange,` she will complete the connection by inserting the calling plug of the cord circuit in use in the jack ofv the proper local line, assumed to be the jack J She will then operate her ringing key K2 to signal l the-called subscriber. When the plug is inserted in the jack J a circuit is .completed for-the supervisory lamp L* inthe usual manner over the sleeve of the 'cord circuit, As regards the supervisory lamp La, this `lamp isuiot now illuminated, for the direction' of current flow through the windings of the, polarized relay 202 is such that the armature of this relay is operated to open the circuit of the said supervisory lamp L3. l

When the local subscriber answers, his transmitter is supplied with talking current through the windings of relay 221 at the cord circuit. rlfhis relay is accordingly energized tov break the circuit of the supervisory lamp L, thus advising the operator that the called party has answered. The relay 220 serves no purpose in a connection .of this character, being o't' utility only when on local connections and remains deenergized. I

" The required connection hasnow been established. The transmitter at the calling substation is supplied with talking current,

through the windings of the double wound relay 100 at the connector, while the\trans mitter'at thecalled substation is supplied with talkingcurrent through the windings of the relay 221 at the cord circuit O as before mentioned.' The path for voice currents is shown in heavy lines and needs no detail description.

When the conversation is over both sub# scribers will .replace their receivers'. `When the receiver is hung yup at substation A `the relay 221'isdeenergize`d,"l thereby again closing the circuit of the supervisory lamp L* to give the operator disconnect signal.l When the receiveris replaced at the substation Athe circuit of the line Arelay 100 is broken, whereby the line relay deenergizes and closes the previously described energizing circuit for the slow acting relay 106, the rotary magnet not being operated because the branch of this circuit which includes its winding is now open at the-armature 144 of relay 108. Upon energ1zing,`the' relay 106 disconnects t-he conductors 160 from the upper Winding of relay 108 att its armature 135 and at they same time closes the energizing circuit of relay 10Z.. Upon energizing, relay 107 reverses the line wipers 191 and 194 as regards'their connections to the windings of the answeringbridge relay 110, thereby reversing-the direction of current' flow over the trunconductor .20D-201.,

By this operation the olar'ized relay 202 at ,the branch4 exchange is operated 'to closethe circuit of thesupervis'ory lamp L3- in an obviousmanner. lThe operator is thusgiven a disconnect signal by the called subscribers.'

An instant after theA energization of relay 106 the'- slow acting vrelay 101 deenergizes,

b oth then'calling and.

its circuit having been broken by the deenergization of the line relay 100. By the denergization of the relay 101 the circuit of' relay-106 is bro-ken at armaturell and at armature 114 ground G is disconnected from conductors 160 and 16`1. Since relay 110 is stillv energized. howeier, conductor 161 remains grounded for the present overl an alternative path which ma be traced as `follows: 4grou-nd at G10, working contact oi armature 145 andthe said armature, armature 125 and its working contact, and the armature 148 -and its working contact to the conductor 161.V Relays 103 and 108 whose locking circuits include the conductor 161 arc thus prevented from deenergizing When ground is disconnected from conductor 160- the holding circuit over which the switching relays 87 andv 5T ot the. selectors' F and E, respectively, and the holding winding 17 of the line switch C have been energized is broken. Upon the deenergizar tion of relays 87 and 57 the selectors F andll are restored to normal ythrough the medium of their respective release magnets 8 4 and :16.in the. usual and well understood manner. Upon the deenergization of the v` holding winding 17 the plunger ofthe line switch C is withdrawn from the bank, whereupon all ot' the automatic switching apl paratus involved 1n the connectlonjvith the exception of .the connector H will have been restored to an idle condition in readiness for another call. An instant "after ground G6' is removed from conductor 160J to permit the release of the selector switchesand the line switch as above described, the slow acting relay 106 deenengizes and ground G10 is thereby connected to conductor 160 over the following path: ground G1, working contact oi' armature 1 45 and the said armature, armature 125 and its working contact, armature 148 and itsworkingfcontact. con'- ductor'161, .armature 141' and its right-hand f working contact` upper winding of relay 108, resting contact of armature 135 and the said armature, resting contact of armature 126 and the said armature to conductor 160. Therupper winding of relay 108 isof low r'esistance, preferably about 100 ohms, and the test contact 94 and its multiples are therefore'brought sufficiently near to ground potential to make the connector H busy.

As a further result oi the deenergization' of the relay 101 a circuit is closed forthe rela 164 over the following path: ground at 7,' armature 113 and its resting contact, armature 115 and its 'resting Contact, oil' normalsprings 118 and 117, armature 149 and its working contact, lower-winding of ,sin

be' maintained enrgized'after its initial energizing circuit is broken.` l By the operation of relay 164 the lamp L is lighted., The lamp L is in the nature of an olf normal signal and with rlay 164 is preferably common to the group of connectors of which the bridge at the branch exchange the answering bridge 110 at the connector H is deenergizedwith lthefollowin'g results: At armaturev 148 ground G1 is disconnected from conductor 161 to permit the deenergization of relays 103 and 108. At the working contactof armature 149 the circuit of relays 107 and 164 is broken, whereupon these relays deener'ize also. Finally at the restingcontact o armature 149 a-circuit is completed for the release magnet 111 over the following path; ground at G7, armature 113 and its resting contact, armature 115 and its resting contact, oli' normal springs 118 and 117, armature 149 and its resting contact, and

the' winding of release magnet 111 to bat tery. The connector H is then restored to the medium of the said release magnet.

In case the callin subscriber at substation A desires to o tain connection with another substation, and through accident or design, does not first hang up his receiver to release, but starts to operate his calling device a ain, the relays 106 and 107 are energized uring each series of impulses. By thev operation of the latter relay current in the trunk conductors 200 and 201 is reversed to operate the polarized relay 202 (as before explained.' The supervisor lamp L is thus illuminated.intermittently ihr the purpose of recalling the operator before she takes down the connection. In case` the operator at the branch shouldfremove the plug from jack J before the subscriber at substation A -hangs up his-receiver the answering bridge relay 110 is deenergized andcloses a circuit for, the supervisory lamp L as follows: ground at G1,Working contact of armature 145 and 'the said armature, armature 125 and its working contact, armature 148 and its resting contact and the lamp L to battery. The

relay 107 and the winding ofthe relay 164 lamp L is similar to the lamp L', that is, it

to battery. It will be noted that this circuit is completed before the deenergization of the slow acting. relay 106 occurs, from which it will be seen that the relay 107 will is an of knormal signal common to the group of connectors'and indicates that a complete connection throu h `the automatic switch board has been le up owing to the *failure lao' ' ceiver.

of the calling subscriber to replace his re- It will now be assumed that all the trunk lines of the particular group in question, including the trunk line 200-201 as shown of these lines the 'connector employed will have no automatic trunk selecting movement. v

Having described my invention what] consider to'be new and desire to havewpro'- in the drawing were busy at the time that tected by Letters Patent willbefpointdfout the connector I-l was operated as previously described. Under these circumstances there will be a ground potential upon the test contact 197, and since the trunk line shown is the lasttrunk line-of the group, uponthe test contact 1 also. When the test 'wiper 192 therefore arrives lat thetest contact 196 a circuit will bezcompleted for the test relay 104 as follows: grounded *test contact 196, wiper 192, resting contact of armature 133 and the said armature,'contact 127, spring 128, armature 136 and its working contact, winding of test relay 104, armature 144 and its-resting contact, and the winding of the vrotary magnet L109 to battery. The test re- .lay 104 is short circuited, however, until the stepping relay 105 deenergizes upon the 4last operation of the rotarymagn'et 109, and

does not energize therefore-until the armature 132 separates from its working contact. The instant `this occurs relay 104 energizes in series withfthe rotary, magnet over the circuit just described, Owing to the high resistance of relay -104 thex rotary magnet 109 deenergizes and remains inoperative.'

Upon attracting-its armature 126 relay 104 breaksd its original energizing circuit and completes a locking circuit for itself as follows: ground at G, working contact of armature 114 and the said armature, con ductor 160, armature 126, spring 128, armature 136 and its workingcontact, winding of the said relay 104, armature 144 and its,

resting contact, `and the winding of `the rotaiymagnet 109 to battery. As ay further result of itsenergization relay104 opens that`portion of the rotarylmagnet circuit whichA extends back tothe line relay given a busy signal informin lhim that for thetiine beilig the called su scriber is inaccessible.

. substantially as'before described.

lower rheavy tal ing conductor. -1 B v100, at its armature 129; at its armature '163 opens the circuit' of the stepping relay 105; and at its armature 130 connects a lead.,

from the'busy si ailing machine Q to the latter. operation the ,calling subscri er is e will therefore lhang up his receiverand "the automaticy switches involved 'in the connection will` be released `I wish vit to be understood that the group of qonnectors of. which .the connector H 'is one in ayhave access to individual subi lthe local1circuit's of said switch',v a tem ti'aink lines'-= The ltwo Itestcontacts, 'correspending to test contacts 196 and 197, of

each suchv-.indivi'dual-line shouldv be joined together, ofv courseyand when calling` one in the 'ap ndedclaims.

What claim as my invention is:

' 1 In a telephone' system, a temporarily established connection including in serial relationan. automatic switch, a trunk line,

andan operators cord circuit, a signal at the'operators position, a calling device at relation an automatic switch, a trunk line,l

and an operators cord circuit, a signal at the o erators osition a calling deviceat.

P P a the calling substation for controlling said switch, a relay responsive to the operation'v of said calling device after the yconnection is established for reversing the direction of current flow in said trunkline, and a device `responsivet'o such reversal to actuate said signal. v

' 3. In a telephone system,M subscribers lines, means including a linal connector switch for extending a-connection from a calling line to a called line, mechanism for releasing said switch at the end of the conversationv controlled over the line circuit which is opened last, and a signal automatically f actuated if the called line 'circuit is .Opened first;

4. In a telephone system, subscribers lines', means including a nal connector? switch for `extending a connection from a calling line to a called line, mechanism for releasing said switch at the endof the connef' yversation. controlled .over the liney circuit.,`

hich is opened,last two* signals associated withsaid lswitch, means for automatically-i line circuitl i s opened first, and' means for( 5. In a tele hone system, a, connector switch having irective relay controlled pri actuating one of said signals if the callingfjh automatically. actuating the other of said,` I signals ifthecalled line circuit is.- opened each having ut two positions'.,. hawngY sole control of all {iref -rilyest-ablished connection between a ca in and -a called line including saidf switch, an

mechanism; o'r releasing said switch at the gud gf .theconversation under the 'control ofthe line circuit. which is last opened. 6.: In" a .telephone system, a connector v onda anotherone of said first lines-circuits. for I controlling the the,l local circuits of said established connection between -a ca ing render it eil'ective.

extending cuits `for controlling the switch having directive 'controlled primary .and secondary o rating magnets, a liirality of switching evices, each havin ut 4two positions, having sole'control of a said iirst=lines,. means in said switch oper v ated if the'first one of'said line is busy for causing saidswitch to lautomatically select rim yv and` secondary 'movements o'f said) 'swgdh and forstarting and'stopping the idle line selection, and 'a plurality of circuit changing switching vdevices, each havingjbut two positions,.having sole control of said circuits.

8; a telephone system, a group of lines extendm from .an exchange 'to ay distant point, ot er lines, 'an`1 automatic 'switch' having directivelycontrolled primary and secondary movement for,.,connecting a calling one of said other lines 'with the `firstv one of -said first lines, means in said switch operated automatically for selecting; anotherone of said first lines if the first one is` busy, cirandsec` ondary inovementslof switch j and for startin i andv stopping'theidle lille selection, a plura ityy ofscircuit changing switcliiiigde-` vices, 'each having butl two positions, having mechanism sole 'control' ofsaid v circuits; and .releaseuiring vthe 'openingof both- :he connected linecircuits'to renderit efecive. v 9. In a telephone system, an automaticdif. rectively lcontrollable switch having alito.

' f, directively controllable matic trunk 'selecting :Eu maia nsi,l trunk -liiies ac cess'ibleto .said switch, test contacts for mid linesf'and vak s :ffoperatm'gv wiper in said switch, a `lineswitchiiig relayiii said switch, vii. relay-'controlling thej' automatic f Y tendin'g'dfromj'saidtest wiper through said relays, res vely, to'th'eopposit'e poles of the` centra batte said jcircuits being' ex-z I o t eriwipei' ofsaidswitchi' means, or* automaticaly' closing said irectively elusive of an circuits at therend pf the trolled movement of saidswitch.- 5

10. Inatelephone 'system switc havin vautor matictrunk selecting functions, "trun lines 'accessible to saidsvt'itch;v test contacts forf said 'lines and a cooperating test` wiper in switch, a tem ora-` to extend a connetcion to a particular line,-

magnet'in series` means controlled by sai "en .automatic `magnet exclu tive to short circuit the said; relay yvlicriflg saidv switch, a line switching relay in said switch, a relay -controllingl the automatic trunk selection,., arallelbranch lcircuits ex- .tending from said test wiper through said lrelays, respectively, to the opposite poles of the centra battery, 'and a rela energized ,during the directively controlle movement v"of said switch and' deenergized thereafter-to close said circuits simultaneously.

1 1. In a telephone system, a'n automaticy .directivel controllable switch and. lines accessible thereto, test contacts for said lines and a cooperating testwiper in said switch,

test and' lswitching relays in said switch l' adapted respectively, to prevent and ,to com- Aplete connectionto a called line, parallel ranch circuits extending from said test wiper through said relays, respectively, to

the opposite poles of the central battery, an operatin magnet, anda slow acting relay energize' in'parallel therewith during the `o erationofsaid ,switch and deenergized ereafter to close saidbranch circuits. 1.12. In .a telephone system,- subscrbers lines, an automatic connector switch, means foroperating said switchlto connecn with a desired called line, test and switching relays in said connectorada ted, respectively, Ato i -prevent and to comp ete connection to a' called line, an operating magnet-dor said switch, -a slow acting relay energized in parallel'ftherewith durin the operation of `said switch an'd deenergized. thereafter Ato close a circuit through said relays in series, and a test 'wi 'rconnected tothe ,junction fof said relays and coo rating with the test contact ofthecalled ne to cause the ener-f` `gization of either the-said test relay or the said switching relay, depending on whether the called'line is busy'or idle.

13. In a telephone system, subscribers-f f ia test' relay adapted to. prevent con'iiectii'i'A with said calledline if the sameis bu -anda test circuit. including thel said-rela' ndlmignet ,inf series, a melans controlli sai Are ay' or giving a usy signa tli'ecalling subscriber;

14.- In aV telephone system, subscribers v `lines,`a final connector switch havingftosaid 1ines`,'a v directively operablenina'gnefjl' for'saidswitch. for controlling said s v'vitch .1?0..

-a particular line, .v

to extend acomiection to A a test relay ada revent connectie` Wthsaidcalled' exif e same'is busy,jA test circuit qinclii'dii'ig the saidrelay a'n relay for vin a subscribeiglandgan usy said relay 'a'iiide'ec-- b oeratingcircfuit for sai t e lines, a final connector 'switch having access f 'to jsaid lilies, a directively operable magnetj j: for said switchfor controlling 'said switchyr10 17. A connector i1 lay in series with said magnet when the` called line is busy, to signal the' calling subscriber and prevent the further operation of said magnet.

16. In a telephone system, subscribers lines, a final connector switch having access lto saidlines, a directively operable magnet for controlling said switch to extend a `con nection to a particular group of lines, a relay in s aid switch adapted to prevent connection with all butthe last line of a group of busy lines, another relay operable in series with saidmagnet for preventing the establishment of a connection to said last line, for stopping the operation of. said magnet and for giving a busy signal to the calling subscriber when the cllled line is busy.

uding a relay, line switching contacts on said relay, an energizing circuit and a locking circuit" for said relay, and holding means to retain said relay in operated position after the establishment of said energizing circuit and until said locking circuit is completed.

18. In a telephone system, an automatic switch having a primary movement and a variable vdirectively Vcontrolledl secondary movement inl a dierent direction, a relay, a

wiper of said switch being connected to one pole of a source o f current byV way ofsaid relay while the switchis in normal position,

contacts .arranged in groups accessible to, said wiper, one of sald contacts being connected tothe other pole of said source of current, means for operatmg sald switch 1n its lprimary movement to assoclate said wlper with a particular group of contacts, and

means for operating saidv switch in its secondary movement to close a circuit for said relay by bringing said wiper into engagement with the contact which is connected with said other pole of said source ofcurrent. i

19. In a telephone system, an automatic switch 7havinga primary movement and a directively controlled secondaryv movement, a relay, a Wiper ofsaid switchA being connected to one pole ,of'a source of current by way of said relay while the switch is in nor? mal position, contacts arranged in horizontal levels accessible to said wiper, one ofy said contacts being connected tothe other pole of said source of current, means for operating said switch in its primary movement to associate said wiper with a particular grou of contacts.,l means for operating said l switc in'its lsecondary movement to close a circuit for said relay byl bringing said wiper into engagement-- with the'contact which is connected with said other pole of said source of current, and means for disconnecting'said Wiper from the first mentioned pole of the source of current during the secondary movement. of the switch.

20. In a telephone system, an automatic ments,`said switch having a wiper and a pluswitch having primary and secondary moverality of groups of contacts accessible therei to, one or more of said contacts being connected with one pole of a source lof current, a relay, means for seizing -said switch, means responsive thereto for connecting the wiper with the other pole of said sourcel of current by way of said relay, means frfor operating said switclrin its primar-y movement to associate said wiper with a particular group of contacts, and directively controlled means :tor operating said switch in its secondary movement to close a circuit for said relay by bringing said wiper into engagement .I

" with' a contact in the selected group. I 21. In a telephone system, an automatic switch having primary and secondary movements, said switch having a wiper and a plurality of groups of contacts accessible thereto, one or more of said contacts being connected with one pole of a source of current, a relay, means :forv seizling said switch, means responsive thereto Lforl connecting the wiper with the other pole of said source of current by way of said.relay,means for operating said switch in its primary movement to associate said wiper with a particular groip of contacts, directivelyl controlled. means or operating said switch in its secondary movement to close a circuit for said relay by bringing said wiperl into engagement with a contact in the selected group, andmeans for disconnecting said wiper from the second named pole of said source of current during the secondary movement, ot' the 4 switch. v

22.A In a telephone system, an automatic' switch having primary and secondary movey ments, said lswitch having a wiper and a plu'- rality of groups of contactsaccessible therev to, one or more of -sai'd contacts being connected with one pole of a sourceof current, a relay, 'means for seizmg saidswitch, means responsive thereto for connecting the wiper with the other pole of said source olicurrent byway of said relay, 'means for operating said switch in its primarv` movement to associate said wiper with aparticular group of contacts, directively controlled lmeans for operating said switch i its secondary vmovement to-close"v a circ t for said relay by bringing said wiper into engagement with a contact inthe selected grou-p, and'means for preventing the operation of said rela dur-v ingthe secondary movement of the switch.

23. In a telephone sys-tem, av connector switch' having a wiper, a relay associated therewith, a called "line having a' bridgev cutoii' relay,a contact connected with the last(` .contact to close. a circuit including both o f said .relays and said wiperv in series.

24'.' In a teiephone system, a connector switch having normally disconnected line wipers' and a test wiper, a called line accessible to said line'Lwipers, a test contact forl said called line accessible to saidtest wiper, said test contact being connected with one pole of a source of current, a relay for-connecting said line .wipersto the switch, means forbrlnging saidlmewipers.into engage1 ment with the called lineA and said test wiper into engagement 'withfsaid `test contact, means forconnecting said line .wipers with 'the switch "by energizing lsaid .relay over a circuit inc1uding'sa1d-1testcontact and said test '.wlperg-in Iseries.,.and means for shunting said :"ray so'A as to'place ya guarding 'poten-' tial oi.. said test: contact.

2 5. In a telephone system, aconnector switch having normally disconnected line wlpers and a test wiper a 'called'lineacc'essible 'to said line wipers, a test contact for said called 'line accessible to said test wiper, said test contact-being connected with one pole of a lsourceof current, a relayJ for con-l necting'said'line wipers to thejswiteh, means for brlnging saidline' wipers into engage# wiper into engagement with said testI ment with the. called line and said test contact, means for connecting said line wlpers with the switchj by energizing said' relay over a circuitincl'uding said test contact and said test wiper in series, means fort' shunting said relay so as to place a guarding` shunted.'

potential on said test contactsand means for malntaining said relay energized after -is 26.*In atelephone system, a'lconnctor switch Ihaving normally disconnected line v .operating sald switch to cause said wipers i 115- line,'a switchi ngrelay` in said connector,

wipers'anda test wiper, 'a called'line accessi-v ble to, said. ine wipers, a` testj contct :forl said called line accessible to said testwiper,

- said test contactbeingconnected with one pole of a source (jt-current, a relay for .con-` necting said '11newipers tothe switch, means 4for bringing .said 'line wipers into .engagement v'with the called line and said test wiper into engagement withv said test Contact, means lfor connecting said line wipers with the switch b y energizing said relay yover a circuitincluding said test contact and saidtest wiper in series, means for shunting said relayk so as, to, place a guarding potential on said test contact, andl means including a separate windlng on said relay'for maintaining it energized after it isshuntedf gized after it is 'shunted 28. In a telephone s stem,fa connectorl ng conductors 'and 27. In a'telephone system, a `connector switch having` normally disconnected line wipers and a test wiper, a called line accessible to said line wipers, a test contact for said called line accessible to said test wiper,

said test contact being connected with one pole of a source of current, a relay for connecting said line wipers to the switch, means v for brin 'ng said line wipers into engagement wit t ecalled line and said test wiper into engagement with said-test contact, means for connecting said line wipers with the switch by energizing said relay over a circuit including said test contact and said test wiper`- in series, means for shunting said relayso as to place a guardin potential on said test contact, and means or closing anj other circuit for said'relay inclu g a second winding thereon to /mainta it enerswitch including two tal two line wipers, a called line, means for operating 'said switch to lcause said wi rs to com xectwith the two conductors of said line, a switching relay .in said connector, contacts. on. said relay for connectlng. said' talkmg conductors with said wipers,'a third wipe1 f on said connector, a cut-ofi' relay for the called line, and a circuit including said third wiper for energizing said switching relay in .series with'said cut-QE relay. f v

, 29,':I'n 1a telephone system', a: connector switch including ltwo talking conductors and' two line wi rs,-a calledlin'e, -meansfor oplerfating sai switch to cause saidwi yrs to connect with the two conductors of said line,

a switching relay in said'conneetorlfor con# necting said ,talking lconductora with said wipers, a cutoff relay -for the ca alledy line, a-

circuit' for energizing vsaid switchingrelay in :los

f series with said cut-oli relay, contacts on said.

switching relay for closing a newgeircilit for;

the' cut-oil` relay alone, andfalocliing'eircuit for saidswitching-relay, ya

v 30. In4 a telephone `Vsystem-,

twojline wipers, acalled line', means for-1:

to connect' with theztwo conductors ,of said contacts on said relay; for' connecting said talking conductors with said wipers, a cutoi relay fon the calledline, a circuit for enf;

er izing saidswitching relay in series with sald cut-off' relay, and means actuated automatically during thek operation of said' connector for .holdingsaid circuit open un;-

til after the Said wipers have completed the to connect with a ca led line, a switching relay for closing the talking connection, a test re ay for preventing the closing of such con'- `test relay and slow acting relay.

32. In a telephone system, a connector switch, means for operating said connector to connect with a called line, a switching relay for closing the talking connection, a test relay for preventing theclosing of such connection if `the called line is busy, a slow aeting relay maintained energized while the switch is operating, a circuit 'For saidtest relay controlled by said slow acting relay, and a circuit for said switching relay controlled jointly by said test rela \v and slow acting relay.

33. In a telephone system, a connector switch, means for 'operating said connector to connectwith a called line, a switching re.- lay for closing the talking connection. a rtest relay for preventing the closing of such connection if the called line is busy, a slow acting` relay maintained energized while the switch is operating, a circuit for said test relay controlled jointly by said slow acting relayand .said Switching relay, and a circuit tor said switching relay controlled jointly by said test relay and slow acting relay. A

34. In a vtelephone vsyste-rn, a connector switch including a talking conductor and a line/wiper, a called line, means for operat- -ing said switch to cause said wiper to connect with ,a conductor of said line, a switching relay in said connector for connecting said talking conductor with said wiper, a cut-olf relay for the called line, a circuit Jfor energizing said switching relay in series with. said cnt-ofi' relay, contacts on said switching relay for closing a new circuit for the cut-olf relay alone, and a locking circuit for said switching relay. l

35. In a telephone system, a trunk line terminating in an automatic switch, groups of lilies accessible to said switch, means for seizing said trunk line and for operating said switch to select one of said groups of lines, means orinitiating an automatic secondary movement of said switch to select any idle line in the selected group of lines, a relay energized when an idle line is found for completing a connection to said idle line, a circuit for the winding of said relay including a conductor ofsaid trunk line, 'an-d means for closing said circuit to operate said relay.

36. In a telephone system, a connector lswitch including a talking conductor and a line wiper, a called line, means for operating said switch to cause said wiper to connect with a conductor of said line, a switching relay in,l said connectorV for connecting said talking" conductor with said wiper, a cut-oil relay for the called line, a circuit excluding said wiper for energizing said switching rela-y inseries with said cut-ottl relay, contacts on said switching relay for closing a new circuit for the cut-oil'A relay alone, and a locking circuit for said switching relay.

37. In a telephone system, a side switch-I less connector having tWo directive motions, for selecting a called line, a two conductor talking circuit' extending through said connector to the wipers thereof and comprising three normally disconnected sections, a ringing generator normally operatively associated with the middle section, a cut-oil relay for the called line, a switching relay in said connector energized in series with said cut oil relay when the called line is selected, contacts on said relay for joiningthe middle "and last sections to ring the called line, a

ring cut-off relay 'energizing over said two connected sections on the response of the called party7 and contacts on said ring cntoff relay for disassociatino' said middle section andthe said ringing machine and for connecting the .middle section with the first. section to complete the talking circuit through said connector.

- Signed by me at Chicago, Cool.y County, State ot Illinois, this 6th day oi June, 1917.

EMIL JACOBSEN'.

Images