US1301648A - Automatic and manual telephone-exchange system. - Google Patents

Description

W. L. CAMPBELL Ge T. G. MARTIN.

AUTOMATIC AND MANUAL TELEPHONE EXCHANGE SYSTEM. APPucmoM FILED APILH. 1901.

1 ,301 ,648, Patented Apr. 22, 1919.

3 SHEETS-SHEET I.

W. L. CAMPBELL 6: T. G. MARTIN.

AUTOMATIC AND MANUAL TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED APR-23.1907.

1,301,648. Patented Apr. 22,1919.

3 SHEETS-SHEET 2.

W. L. CAMPBELL & T G. MARTIN.

AUIOMATIC AND MANUAL TELEPHONE EXCHANGE SYSTEM.

APPucAnou mm APR. 23. 1901.

1,301 ,648. Patented Apr. 22,1919.

3 SHEETS-SHEET 3.

STATES PATENT OFFICE.

JVIIaSQN L. CAMPBELLJLND TALBOT G. MABTIN, OF CHIQA GO, ILLINOIS, ASSIGNORS, BY lIEfSNE' ASSIGNMENTS, TO AUTOMATIC ELECTRIC COMPANY, A CORPGBATION OF initiators.

.AIUTQMEAIICAND.MANUAL TELEPHONE-EXCHANGE SYSTEM.

Specifieation of Letters Patent Patented.Apr. 22,-1919.

Applicationfiled April 23, 1907. 'iseriahlTm 3695808.

' Toallwhom it may concern "F Bait known that we, WILSON L. CAMPBELL and*T-ALBorr G; MAn'ITN, both citizens of the United States of America, and residents of flvfihicago, .Gook county," Illinois, have inventedacertain new and useful Improvement in sters or-calling devices. However, when a manual subscriber-calls van automatic subw-iAutomatic'and Manual!Telephone-Exchange of the originating and trunkin operators,

Systems, of which the =following is a speciulfiflfliblOIl. izOur invention relates to telephone exchange skystems in generahbut more particuilarly tosystems in which both manual and 1 automatic apparatus is employed, and especially to; systems in which the subscriber of amanual exchange may call and obtain con- ,nection with the line of a subscriber of an automatic exchange. One'of the: principal objects of our invention is, therefore, the provision of an ar- I rangement whereby a manual subscriber may call .an automatic subscriber, through the medium of: orginating and trunking operators I cord: circuits, and vwhereby the origimating operator may have complete supervision over the connectionthus established. As hereinafter described We accomplish this -.by ::providing an originating operators switchboard to which are connected the lines 1 of manual subscribers. Suitable line-signal i'sfliapparatus. is provided by which the subscribers may attract the attention of the operator, and on the same switchboard are one or more jacks connected with trunk lines extending to a trunking operators position or 36'SWl'tcl1lb0aid. At the trunking operators position we provide "one or more jacks connected with trunk lines leading to the automatic exchange, and at the said exchange these trunk lines terminate in second-selec- 40 tors. In addition, the trunking operator is provided with an impulse transmitter or cal ing' device by whic the said selectors can be operated afte11 connection is made with one of the trunk 'l iries leading thereto. We

-4 5 also equip the said automatic exchange with third-selectors connectors, the third-selectoi's being interposed between the second "selectors and the connectors, and all of these automatic"switches being responsive to the t0 impulse-transmitter or calling device includ ed in the trunking opera-tors equipment. For the benefit of the automatic subscribers,

and as a means of intercommunication bescriber, the manual-trunking operation, accomplished through they trunking operation corresponds to the first digit o the called number, and the automatic trunking and :connectingoperations corresponding to the other four digits of the calledcnumber are then accomplished at the automatic exchange, and are under the control of the trunking operator. The trunking connection thus afforded between manual and automatic subscribers is supervised by the origimating operator at the cord circuit of the latter at the manual exchange, and disconnect signals are'given when either or' both subseribers hang up their receivers. 'In this way-satisfactory service is given between the subscribers oflmanual and automatic exchanges, and ats'theasame time, of course,

the manual subscribers can call manual subscribers, and the automatic subscribers can call automatic subscribers.

It is'also an object, of course, to provide certain details and features of improvement and combinations tending to increase the general efliciency' of a telephone exchange system.

To theforegoing and other useful ends, our invention consists inmatters hereinafter set forth and claimed.

Inthe accompanyingrdrawings Figure 1 represents diagrammatically a manual substation Aconnected with a central ofiice in- .volvi-ng equipment usually found in a cen- -ilm'aticiexchangesg such asthe one the switches of which are shown diagrammatically in Fig. 3 and which will be designated as the sub-automatic exchange.

Fi s. 1, 2 and 3 taken together show an estab ished connection extending from the manual substation A (Fig. 1) to the automatic substation A (Fig. 3).

The substation A suitable or approved type. The one in connection with which we have elected to illustrate our invention comprises a receiver 2, a switch-hook 3 for controlling the substation circuits, which controlling operations are accomplished through the medium of any suitable means, such as the cam-arms 4, 5 and 6. As the switch-hook is lowered the cam-arm 4 momentarily presses the release springs 7, 8 and 9 into engagement, whereby the substation line conductors may be grounded simultaneously. When the switchhook is down the cam-arm 5 engages the spring 10, thereby bridging the ringer 11. across the line. Furthermore, when the switch-hook is down the said cam 5 disengages the springs 13 and 14, thus breaking the local circuit which includes in series the primary winding 15, transmitter 16 and local battery 17. The substation ground circuit is normally broken between the ground springs 18 and 19 by the cam-arm 6; but when said springs are together ground is provided to the ground post 20 and to the release spring 7, as is usually the case in telephones of this type. The said substation comprises the usual induction-coil 21 having the primary winding 15 and secondary windlng 22. Bein an automatic substation it is provided wit the usual vertical and rotary impulse springs 23 and 24. Said substation is, of course, provided with a dial (not shown) which is secured to the shaft 25, together with the locking dog 26. Furthermore, there is a locking cam 27 that locks the dog 26, while the receiver is on the switch-hook, to prevent a rotation of the dial. For operating the impulse sprin s 23 and 24 the substation is provided wit an impulse wheel 28 that is secured to the shaft, which im ulse wheel carries on its periphery the so-ca led vertical impulse teeth 29 and one rotary impulse tooth 30. The said impulse teeth are so arranged that when the dial is drawn down the lmpulse springs 23 and 24 are not carried into contact with the ground post 20; but as the dial returns, first the vertical teeth enga e the vertical impulse spring 23, and aer they have completed their work the rotary impulse tooth 30 o crates the rotary impulse spring 24. In .t is operation the subscribers vertical line conductor 31 is first given a number of ground impulses, and then the rotary line conductor 32 is given one ground im ulse. It will be noticed that as long as the ial is out of normal position the construction is (Fig. 3) may be of any 7 such that the dog 26 permits the primary circuit springs 33 and 34 to separate, thus preventin the impulses that are delivered to either line conductor from ass to the other. The means whereby t esu scriber may signal the called subscriber comprises the push-button sprin 35 which normally engages the contact point 36; but when the button 37 is pressed the spring 35 engages the contact point 38, whereby the vertical line conductor 31- may be grounded.

The second-selector D is substantially the same as the selector switch disclosed in United States Letters Patent No. 815,321, granted March 13 '1906, to Keith, Erickson and Erickson, with the exception that there are no normal conductors. There is no necessity in the second-selector for a brid ecut-ofl' relay, and it is also omitted, and t e line relays are. connected directly toithe battery lead. The private normal conductor of the said selector patent is of no utility in connection with the second-selector, and is also omitted. Since the said selector is substantially like the one disclosed in said patent it is equipped with a vertical magnet 39 and a rotary magnet 40, a release magnet 41 and a private magnet 42, the operation of which will be understood. The said private magnet 42, of course, controls the side switch wipers 43, 44, 45 and 46, the said private magnet also controlling the circuit of 'the vertical magnet 39, in the usual manner, by means of the springs 47 and 48, but not of the release magnet, for the release magnet spring is omitted. The vertical movement of the switch shaft, and, therefore, of the wipers 49, 50 and 51, is controlled by the vertical magnet 39, and the rotary motion by the rotary magnet'40, the rotary magnet circuit being provided with the usual interrupter springs 52, The operative magnets of the switch are, of course, controlled by the subscriber through the medium of the vertical and rotary line relays 53 and 54, as is well known. Said re lays have under their control the usual springs 55, 56 and 57, a'ndin addition the trunk release springs 58 and 59, by means of whichlatter springs the said switch may be released when the side switch wipers are in first or second position. By'means of the back-release relay 60 the release oi the switch D is brought about after the side switch has passed to third position. The third-selector E' (Fig. 3) is a duplicate of the second-selector switch D (Fig. 2).

The connector switch F is an im roved form of the connector described in nited States Letters Patent No. 815,176, granted March 13, 1906, to Keith. Erickson and Eri kson. The general mechani al details of the connector F are the same as those of the patented connector, but there are changes in the. circuits. The connector switch shaft (not shown), like the switch shaft of the selector D, carries the line wipers 61 and 62 and the private wiper 63.

i The connector switch is also controlled by the calling subscriber through the medium ofthe vertical and rotary line relays 63 and '64. The vertical line relay 63 directly con trols the vertical magnet 65, and also the 'rotary magnet '66 and ringer relay 67. The "ofl ice of the vertical magnet 65 is to give the shaft and shaft wipers their vertical motion,

sand the rotary magnet 66 imparts to the shaft and shaft wipers a rotary or circular motion. The-rotary line'relay 64. controls.

theprivate magnet 68,which latter, under certainconditions, controls in turn the vertical and rotary magnets 65 and 66, release magnet 69-, and alsothe side switch wipers 70, .71, 72, 73 and 74. 7 The side switch'of 'the'connector, like the side switch of the first-selector, has a normal or first position, a second position and a third position. The release magnet 69 is also controlled by the line relays 63 and 64'conjointly. By the condensers 75 and 7 6 the circuit'through the connector is inductively divided into two sections. The connector F isalso provided with the back-bridge coils 77rand 78, so arran ed that when the side switch passes to 'third position an energizin circuit is closed through the relay 78, which operates to connect the rotary line relay 64 to the called line. Thecentral ofiice is equipped with a busy-signaling apparatus of any suitable design, such, for example, as the one comprising an interrupter 79 in series with the,..primary winding 804015 the inductioncoill 81 whereby a. busy-signaling current is induced in the secondary windingt82 of the coil. Th connector switch shaft also carries a normal post arm 83 which, when therconnector shaft is 03 normal, allows the spring 84 to engage the contact point 85, whereby the busy-signaling-current passes to the line of ;the calling subscriber when the side switch istin first position.

a The first-selector H .(Fig-.-3) allotted to the line of the-substation A is of the. type disclosed in saidselector atent.

It will be understood t at the manualexchange, which is shown in Fig. 1, and which may be designated as the main manual exchange, has allotted to it, of course, a plu rality of subscribers each provided with a substation, such as the substation A.. These subscribers may readily be put in connection with one another through the medium of cord circuits, such as the cord circuit 0,1):- they may be put in connection with the automatic subscribers of the main automatic exchange (Fig. 2), or of the sub-automatic exchange (Fig-3).

It will' further be understood ,that the main automaticexchange to which the se lectou D; 1 (Eig 2) belongs may lhaveallottedto it a plurality of automatic subscribers cash provided with a substation, such as the substation A (Fig. 3), each of which substations has allotted to it a first-selector,

such as the first-selector H. The said firstselectors are adaptedi-to be operated, in the manner well knownpto establish connection with a second-selector, such as the secondselector D, and with other selectors if necessary, which last selector is in turn adapted to establish connection with local connectors, similar to the connector F, for obtaining connection with local subscribers. If it is desired to obtain connection with the automatic subscribers of the sub-automatic exchange (Fig. 3) a second-selector, similar to the second-selector D, is, of course, operated to a proper level from which trunk lines lead to the sub-automatic exchange (Fig. 3), among which is the'trunk line that terminates in the selector E. The sub-automatic exchange also has'allotted to ita plurality of substations, such as the substation A, each of which substations has allotted to it a first-selector, exactly as the substation A has allotted to it a first-selector.

The method of o eration of the system will be understood rom the following: -If

the subscriber at the substation A (Fig. 1)

order circuit, transmit the order to one of the outgoingtrunking operators. The trunkingl operator upon receiving the order will designate to the subscriber-ls operator which trunk .to take. The subscribers operator "thereupon willplug in the jack of the designated trunk atthe same time that the trunking operator-selects one of the trunk lines leadingtouthewmain automatic exchange It will be..understoodthatif an. automatic subscriber were calling the numbe'rl2922O he would; have to operate his dial five times, once in accordance with each digit; but

:when a call comes from the manual subscriber A the preliminary operations of the line and trunking operators, above ex plained, will correspond to the operations of the automatic subscriber for the first digit 2, and consequentlywhen the trunking operator begins to operate her automatic calling device forcalling the said line #29220 the first digit is omitted. The trunkingoperator then operates her automatic calling device inaccordance with the digit 9 to operatethe selector Dasha next operates her calling device in accordance with the second digit 2, for operating the selector E to connect with the connector F. Subsequently, the calling device is operated in accordance with the last two di 'ts to operate the connector and for there y completing the connection, if the line is idle.

In detail, the establishn'lent of the connection is as follows: When the subscriber at substation A removes the receiver from the switch-hook an energizing circuit is closed through the line relay 86. This circuit extends from ground Gr through the transmitter 87 of the substation A to the armature 88 and to the contact point 89, to the line relay 86 and thence to the battery lead 90, and through battery B to ground G. The line relay upon energizing operates to close in contact the armature 91 and contact point 92, whereby the circuit is closed'through the line lamp 93. The operator upon observing this signal will answer in the usual manner by placing one of the answeri plugs p in the answering jack correspoiiging to the lamp. She then throws her key It to listen. When the plug 2 engages the jack an energizing circuit is established through the line-cut-ofi relay 94. This circuit extends from ground ,G through the relay 94, through the sleeve of the jack to the sleeve of the plug p, relay 95, battery lead 90, thence through battery B to ground G. The relay 94 upon energizing attracts its armatures 87 and 88 to engage with the contact points 96 and 97, whereby the subscribers line conductors are extended to the operators cordcircuit. Also, when the line-cutofl relay thus operates, the substation A is supplied with battery current for talking purposes. This circuit extends from. the grounded terminal of the batter B throu h the relay 98 to the tip of the p ug p, to t e tip of the jack 7, through the contact point 96 and armature 87, through the substation transmitter to the sleeve side of the line, through the armature 88, contact point 97, sleeve of the jack and plug 7), through the relay 95 to the battery lead 90, and through battery B to ound G. The relays 95 and 98, being inc uded in this circuit, energize and attract their respective armatures 99 and 100. The operator upon learnin that the substation #29220 is wanted will, by pressing the order wire button q, transmit the order overthe line 0 to the outgoing trunking operator at J. The trunking operator at J upon receiving the signal will press the button 9 and thus bridge the talking set is across the order wire. Said. operator J u on receiving the order from the operator C will instructthe operator C which trunk to use. The subscribers operator upon be ing assigned a trunk will insert the plug p into the jack of the trunk designated. At

the same time, furthermore, the trunking;

operator will select one of the trunk lines leading to the automatic exchange and insert the plug p ,of the trunk assigned to the subscri'bers operator, into the Jack j When the plug 19' engages the jack j an energizing circuit is established through the relay 10]. at the cord circuit C. This circuit extends from ground G at the trunking 0perators position J through the relay 102, trunk conductor 103, through the sleeve of jack j and sleeve of plug 7), through the relay 101 to the battery lead 90, and through battery B to ground G. The relay 102 upon energizing withdraws its armature 104 from engagement with the grounded contact point 178, and the relay 101 upon energizing attracts its armatures 105 and 106 to engage the contact points 107 and 108, respectively. When the armature 105 and contact point 107 engage, the ti side of the cord circuit is then completed through the condenser 109 from the answering plug 19 to the calling plug p. When the armature 106 and contact point 108 engage, a circuit is closed through the su ervisory lamp 110. This circuit extends rom the grounded terminal G of the battery through the armature 111, contact point 112, through the lamp 110, armature 106 and contact point 108 to the battery lead 90 and through battery B to ground G. It will be made to appear hereinafter that when the called, subscriber answers, this circuit through the lamp 110becomes broken upon the energization of the relay 113. I Thus far the connections have been made manually-that is, through 0 erators. The automatic continuation of t e manual connection commences at the trunking operators calling device .d. Whenthe plug 10* is inserted in the jack j an energizing circuit is established throu: h the releasing relays 114 and 115. This circuit extends from the grounded ring of the plug 79 through the ring of the jack 3', relay 114 in series with the relay 115, to the battery lead 90, and through battery B to ground G. The relays 114 and 115 are provided for bringing about the automatic release of the automatic switches when the plug 79 is removed from the jack 7'. The relay 114 is a quick acting relay, while the relay 115 is arranged to operate slowl When the relays thus energize in series nit armatures 116 and 117 of the relay 114 disengage from the contact points 118 and 119 before the armature 120 of the relay 115 engages the contact point 121; and then when the relays denerg'ize, the armatures 116 and 117 of the relay 114 engage their respective contact points before the armature 12G disengages from the contact oint 121. Havin established connection with the selector the first digit 2 of the number 29220 is eliminated, as already explained. The operator then throws the key 1: so that the springs I30 175 and-177", respectively from the contact points 1 76' and 178 andcarried into engagement with the contact points 179 and 1 80", from which last-named contactpointsconductors lead to the calling device 05, which calling device is then operated in accordance with the remaining digits 9; 2, 2 and 0. Therefore, the so-called vertical push-button 124 is pressed onto the ground spring 125 nine times whereby'the verticalline relay 53 of the second-selector D is energized nine times over a circuitex- I tend-ing from the grounded sprin 125 through the spring 124, through the fiey 'k" to the =tip=oithe plug-p and the tip-side of the jal'ck 7"; conductor122, side switch wiper 43, vertical line relay 53 to the battery lead 130; and" through battery; B to ground G: Each time that the vertioal'line relay 5351s energized the 5 rings 55 and 56am pressed into contactyw ierehy an energizing circuit is closed. each time through the vertical magnet 39?" The vertical magnet then operates to carry the shaft and shaftwipersi), 50 and 51 nine steps and opposite the banklevel' in which terminate the trunk lines leading to the sub-exchange in which the wline #29220 terminates. -After the callin de vice has been operated for the vertioa i-mpulse the rotary push-button spring =13i"is pressed onto the ground spring 125 once,

whereby a momentary energizing circuit is established through the rotary line relay 54 of the selector D. This circuit extends from ground spring125 through the push-button spring 131'; key to the sleeve side of ithe I plug gu -and jack j conductor 123; side sw-i'tch 'wi per 441110 the) rotary line relay fi if to the battery lead 130; and through Battery B tc ground G; The rotaryline relayien ergi'zes and places the springs 56 and Win contact, whereby an energizing circuit is closed through the private'magnet The private magnet upon energizing and 'den-' ergizi ng operates in the usual manner to permit the side switch to pass fIOm'fiIfSttO When the side switch" second position. wiper45 tngages the grounded contact point in'the' second position an energizing circuit is olesed' through the rotary magnet '46. 7 The rotary magnet now operates to carry theshaftwipers 49, 50 and 51 in a rotarydirw tion and into engagement with thenfirst set of 'trunk line contacts.-- If the first trunk lineis'busy an energizing circuit is =es tab-'- lished through the private magnet extendl ing from the grounded shaft wiperi 51 which engages the busy contact, through the release relay 60, side switch wiper 46, which is in' seco nd position, to the private magnet 42, thence to the battery lead 130," and through battery B to ground G". As long as the private wiper 51 engages busy or grminded contacts the energizing circuit through the private magnet 42 is main-- are disconnected tained,- and theside switch is retained in second position, thus maintaining the energizing circuit through the rotary magnet 40. \Vhen the shaft wiper 51 passes'onto the first idle contact the energizing circuit 70 through the private magnet becomes broken and the side switch passes from second to third positionythus extending the trunk con (111915013 122 and 123 through the side switch 7 wipers 4-3 and 44 to the trunk conductors 132 and 133 which lead-to 'the third-selector Ed Fig. 3) located in thesub-exchange: It will be seen by -referring to Fig. 2 that in series with-the trunk line conductors 132-and- 133-there are the-relays 134 and 135.- These relaysare providedin ordertha t the release:

i of the selec'torD may be brought about after the side switch has passed to thirdposition. The-said-relays are'so arranged thatwhen either relay energizes the springs 136'and" 137'do not engage; but when the relays ener gize simultaneouslythe springs 136 and-137 arepressed into contact, thus closing a circuit through the release relay 60 of the secon-dselec'tor D. The third digit being 2 the trunkingmperator presses the vertical pushhutton spring 124 onto the ground spring 125'twice, andthe rotary push button 131 is pressed onto'the ground spring 125 once; This operation of the calling device closesanenergizingcircuit twice through the vertical linerelay 138 of the third selector E; and an energizing circuit through the rotary relay 139'is'closed once. This circuit through the verti'oal line relay: extends from the ground-i w calrdireotroh and opposite: thelsecondlevellf ofi halnl'r contacts which lead to the connector switches." After the vertical magnet-has thus operated, the momentary circuit that is closed throughthe rotaryline relay 139 may 1 be traiced from the ground spring-12fr at the 1 calling device 0! (Fig. 2) to the rotary trunk 1 conductor 123, thence through the side 1 switch wiper 44 of the selector D and U through the-winding of relay 135 to the ro tary trunk conductor-138, thence to the sideswitch wiper-153 of the selector- B, and

through the rotary line relay. 139 3130 thebattery lead 141, and through battery 13 to' ground G When the rotary line'relay139 is energized the spring 148is pressed into contact'tor a moment with the spring 142,

whereby a momentary energizingcircuit is closed through the private magnet 149, which latter now operates to shift the side switch from first to second position, whereby an energizing circuit is closed through the rotary magnet 150. When the side switch wiper 151 engages the grounded contact point 152 the rotary magnet 150 is operated to carry the shaft and shaft wipers 145, 146 and 147 into engagement with the first idle trunk line conductor-leading connector. Assuming that connectlon is made with the connector F, then when the side switch wipers 140 and 153 pass to third position the trunk conductors 122 and 123 are extended to the conductors 154 and 155 leading to the connector F. The operations of the calling device for the last two digits (two and naught) are directed to the connector switch F. Grounding the vertical line conductor 122 for the digit 2 now energizes the vertical line relay 63 of the con-' nector F. The vertical line relay 63, being to a energized twice, operates to close the springs Y 156 and 157 inoontacuwhereby an energizing circuit is established twice through the vertical magnet 65. The vertical magnet 65 now operates to carry the shaft wipers 61, 62 and 63 in a vertical direction and opposite the bank level in which are located the terminals of the normal conductors 158 and 159 which lead to the substation conductors 31 and 32. When the rotary line relay 64 is operated the privatemagnet 68 is energized and the side switch passes from firstto second position. -When the side switch wiper 72 passes from first to'second posi tion the vertical magnet 65 passes from the control of the vertical line relay, and the' rotary magnet 66 is substituted instead. Now, when the vertical line relay v63 is up erated ten times for the last digit naught, the rotary magnet 66 becomes energized ten times and the shaft wipersv 61, 62 and 63" are rotated ten steps and onto the contacts which constitute the terminals of the normal conductors 158 and 159. Now when there-' tary line relay 64 is energized for the last time the private.magnet 68 is in turn energized, whichunow bperate's with one of two results, namely the rele-aseof the side switch from second to third position,'or the.so-

called busy-release of the connector switch. It will be assumed that the first result takes place that is, that the sideswitch passes from second to third position. If the called line is busy, then when the private magnet 68 energizes for the last rotary impulse the groundon the private contact of the called line is transmitted to the releasemagnet 69. An energizing circuit is then established extending from the grounded contact point to the shaft wiper 63, side switch wiper 74 to the second position contact point, through the two upper springs of the private magnet 68 to the release magnet 69 and battery lead 141, thence through battery B to ground G. The release magnet upon ener 'zing operates to release the switch sha and wipers, and to restore the side switch to first position. N ow when the substation signaling button is pressed the vertical magnet is energized and the switch shaft is raised, and the normal arm 83 permits the springs 84 and 85 to engage, whereby the busy-signaling coil 81 is connected to the line and the busy-signaling current is transmitted to the calling subscriber. When the side switch wiper 74 engages the grounded contact point 160 a guarding potential is established at the private Wiper 63* to protect the called line. This guarding potential also closes an energizing circuit through the bridge-cut-ofi relay '161 of the first-selector This circuit extends from the contact point 160 through the side switch wiper 74,

shaft wiper 63, conductor 162, through the spring 163, oontactpoint 164, bridge-cut-ofi relay 1 61 to the battery lead 141, and

through battery 13 to ground G It will be lay controls t esprings 166 and167. Saidrelay energizes as soon as connection is closed with the called substation. The energizin'g circuit through the relay 78 extends from the grounded contact point 160, throughthe side switch wiper 74, backbridge relay 77, throughthe ringer relay springs and side switch wiper 70, shaft wiper 61, through the hoIm-al. c'onductor158, line conduotort31, through the switch-hook 3 to the ringer spring 10, through the ringer 11 to the rotary line conductor 32, rotary .normal conductor 159, shaft wiper 62, side switch wiper 71, ringerjrelay springs to the relay 78, thence to the battery lead 141 and through battery B to ground G The relay 78 energizes and closes in contact the springs 166 and 167, as explained. The supervisory relay 168 at the trunking operators position now energizes over a circuit extending through ound Gr to the relay 168, and through t e sleeve side of the cord circuit to the key It, to the rotary trunk conductor 123, side switch wiper 44, shaft wiper 50, through the relay 135 to the rotary trunk conductor 133, side switch wiper 153, c0nductor 155, through the supervisory relay springs 166 and 167 to the side switch wiper 73, rotary line relay 64 to the battery lead 141, and through battery 13 to ground G. It will be seen that the rotary linerelav 64 is in this circuit, but the resistance of the coil 168 is so high that said relay 64 does visory lamp 171.

not operatively energize. The relay 168 upon energizing closes in contact the armature 169 and the contact point 170, whereby a circuit is closed through the back super- The back supervisory lamp 171 lights, but not the front supervisory lamp 172, as the relay 102 is 'ener: gized over the sleeve conductor from the calling plug of the originating subscriberss operator, as explained. At the same time, at the .subscribers operators position the back supervisory lamp, .110 is glowing, because battery current is cut oil from the tip trunk line conductor by the supervisory relay 168 at the trunkin operators position, and the relay 113 at t e subscribers operators position cannot energize to attract its armature 111 from the contact point 112 until the supervisory relay 168 denergizes. The trunking operator after having operated the central oilice switches to establish connection with the line conductors leading to substation #29220 presses the vertical impulse spring 121 onto the ground post 125, whereby an energizing circuit is again completed through the connector vertical line relay 63. The vertical line relay upon operating closes an energizing circuit through the ringer rela 67. This circuit extends from round through'the springs 157 and 156, t rough the private magnet springs 163' and 164', side switch. wiper 72, through the winding of the ringer relay 67 to the battery lead 141, thence through battery B to ground G. The ringer relay upon energizing operates to bridge across the line conductors of the called substation the terminals of the ringer generator, whereby the substation ringer 11 isoperated. The subscriber at substation A ,1 having been signaled by the trunking operator, removes the receiver 2 from the switch-hook- 3, and upon referring to Fig. 3 itfwill beseen that-a condenser 173 is in the receivercircuit, so that the circuit through the supervisory relay 78 in the connector F is broken, As a result the springs 166 and 167 separate and the rotary trunk conductor 1564s disconnected from the non-grounded pole of the battery. B this the supervisory relay l68 is deenergize and the armature 169 fallsback against the contact point 174, the back'supervisory lamp 171 is extinguished andthe tip trunk line conductor 103 is conneoted tothe non-grounded pole of the battery. .An energizing current now flows through the relay 113 of the originating operators cord circuit. This circuit extends from the grounded terminal G of the battery B through the relay 113, contact oint 107, armature 105, through the ti o the plug 79 and tip spring of the jac: j, tip conductor 103, through the relay 175, contact point 174, armature 169 to the battery lead 90,- and through battery B to ground G. The relay 113 energizes and attracts its armature 111 from contact with the point 112, whereby the circuit through the back supervisory lamp 110 becomes broken. The

supervisory lamps in both the subscribers and trunking operators positions now being extinguished, the operators will understand that the subscribers are both onthe line. After having finished the conversation the subscribers hang up their receivers. On the automatic side the back supervisory relay 78 of the connector is again energized, since the circuit is again closed through'the' relay-78 and the substation ringer, placing the-springs 166 and 167 in contact, whereby the circuit through thesupervisory relay 168 at the trunking operators position is again completed. When this relay energizes, the armature 169disengages from the contact point 174, whereby the circuit through the relay 113 of the subscribers operators cord' circuit becomes broken. The denergization of this relay 113 permits the armature'lll to engage the contact point 112, whereby the circuit through the back supervisory lamp 110 is again established. If now the manual subscriber at substation A hangs'up his recciver'also, the energizing circuit including the supervisory relay 98'becomes broken and the armature 100 engages the contact point 176, whereby a circuit is completed through the front supervisory lamp 177. The operator seeing both the frontand back supervisory lamps lighted takes down the connect1on. movedfrom the jack j the circuit including the relay 1020f thetrunking operators position, in series with'the relay 101 of the sub scriberls cord circuit, becomes broken and the relay- 102 Ideeuergizes, permittin the armature 104 to engagethe grounde con tact point 178. The engagement of the armature 104 and grounded contact point 178 closes the circuit through the manual supervisory lamp 172 in the trunking operators circuit. The trunking operator seeing both' lamps lighted takes down the connection by pulling out the plug p from the jack j and as a result the energizing circuit through the release rela s 114: and 115 is broken. The relay 114 eing a quickacting relay, as explained, permits the armatures 116 and 117 to engage the contact points 118 and 119 before t e arma-- ture 120 of the slow-acting relay 115 disengages from the contact point 121. By this action the trunk line conductors 122 and 123 are grounded simultaneously for energizing the vertical and rotary line relays of the connector F. When said vertical androtary line relays 63 and 64 of the connector F energize simultaneously the trunlbrelease springs 179 and 180 are pressed into contact, whereby a series energizing circuit is completed through the release relay 181 of the. selector E and the release magnet 69 of the ounded connector F. This circuit extends from the grounded contact point 182 through the side switch wiper 183, release relay 181, through the private shaft wiper 147, springs 17 9 and 180, release ma et 69 to the battery lead 141, and throug battery B to ground G. The release ma et 69, upon energizing, operates in a wel -known manner to restore the connector shaft wipers and side switch to normal position. The release relay 181 of the selector E, upon energizing, closes the springs 184 and 185 in contact, whereby a circuit is closed through the release magnet 186. The selector release magnet 186, upon energizing, attracts its armature and remains in readiness to restore the shaft wipers and side switch to normal position, when the ener 'zing circuit through the release relay 181 ecomes broken, which occurs when the slow-actin relay 115 deenergizes. Also, when the trun line conductors 122 and 123 are grounded simultaneously, the relays 134 and 135 at the selector D energize simultaneously, placin the springs 136 and 137 in contact, Where established through the release rela 60 of the selector D. This circuit exten s from ground through the side switch wiper 46, release relay 60, shaft wiper 51, springs 136 and 137, resistance coil 187 to the battery lead 130, and through battery B to ground G. The release relay 60 operates in turn to close in contact the springs 188 and 189, whereby a circuit is closed through the release magnet 41. The release magnet 41 energizes and attracts its armature, remaining in readiness to restore the selector shaft wipers and side switch to normal position, when the ener izing circuit through the said magnet is bro enth at is, when the slowacting relay 115 denergizes.

It will be seen that the supervlsion of theseconnections rests entirely with the subscribers operator, because the trunking operator does not take down the connection until signaled by the originating operator. Supervision of the signallng of the called subscriber depends on the trunking operator, but the subscribers operator 1s also afforded means to know when the called subscriber has answered. The button a (Flg. 2) is provided in order that the ground may be cut off from the armature 120. This provision is made in order that the operator may remove the plug p and insert another without releasing the automatic selector switches. It will be remembered that when the plug is removed from the jack j the energizing circuit through the release relays 114 and 115 is broken, and the armatures116 and 117 are placed in contact with the points 118 and 119 before the armature 120 disengages from the contact point 121, thereby grounding both trunk conductors 122 and 123; but if the button a is pressed the ground connecy an energizing circuit is tion is cut off from the armature 120, and the de'energizing of the release relays 114 and 115 is without effect, and the transfer of plugs and cords may be accomplished with out taking down the connection.

Suppose that the subscriber at substa tion A- desires connection with a subscriber of the manual exchange. In that event the calling end 1) of the cord circuit C is inserted in the jack corresponding to the desired substation. The ringing key is operated, whereby ringing current from the ringer generator R is projected out on the called line.

It will be understood, of course, that in the automatic oflices of this system the firstselectors, as well as the second-selectors, third-selectors and connectors, are arranged in groups, said secondselectors, third-selectors and connectors being arranged on a percentage basis. For example, in an automatic exchange of ten thousand capacity a somewhat common arrangement is to divide the subscribers and their allotted first-selectors into groups of thousands. Each thousand-group is sub-divided into groups of one hundred. Then the line hundreds that is, the one hundreds, the two hundreds, etc.of the various thousands are each arranged in a separate group, so that in a ten thousand system the one hundreds of the thousands form one group, the two hundreds a second group, etc. Furthermore, each bank level of each of these hundred-groups has allotted to it one group of second-selectors allotted to the thousands corresponding to the level-that is, the second-selectorgroup of the first-selector first bank level is allotted to the first thousand, the second level to the second thousand, etc., thus taking care of the thousands. Furthermore, the second-selector-groups of each thousand are arranged in one group, and each bank level in each of these second-selector-groups has allotted to it a group of connectors, which in turn are allotted to the hundred of the corresponding thousand corresponding to the level-that is, the connector-group of the second-selector first bank level falls in the first hundred of its thousand, and of the second level in the second hundred, etc., thus taking care of the hundreds; there being in a ten thousand system ten one-thousandgroups of first-selectors; ten one-hundredgroups in each thousand; ten cross-hundred groups in the ten thousands; also ten groups of second-selectors, one for each thousand; and ten groups of connectors in each thousand,one for each hundred. With this arrangement it will be understood that the first level of the first hundreds in all thousands in the system are multiplied in a manner well understood; likewise the second level, etc. Also, all like levels of each second-selector-group (one of which, as stated,

menses is allotted to each thousand) are likewise multiplied. In each of the aforesaid c0nnectongrou-psalso, and in the: same manner, the like levels aremultiplied.

From the foregoing it will be seen that the or'ginating operator at C has complete supervision over the trunking connectionestablishscd between the calling manual sub scribcr and the called automatic subscribed. This trunking. connection is established by both manual and automatic apparatus, and through the calling operation oi the orig inatingand trunking operators the trunkingpperator has complete control over the automatic portion of the operation-diet is to say, the extension of the connection by automatic switches. The manual subscribers are furnished with talking current derived from a common battery at the exchange or centralstation, and, as herein disclosed, the automatic subscribers are equipped with 10- cal batteries for talking purposes. It will thus be seen that trunking connection is. affordcd between common. battery and local battery subscribers, and that the common batter, operators have complete supervision over the service thus afifiorded between the subscribers of two different types of exchanges.

What we claim as our invention is:-

l. A telephone exchan e system comprising subscribers lines, an means for tnmking calling lines into connection with called lines, said means including anoriglnatin opcrators cord circuit, a trunking operator s cord circuit, means rwntrolled by the trunking operator for automatically extending commotion iron-i the trunking operators position to the called line, means at the originating operators cord circuit for receiving a disconnect signal from the calling subsrriber, means at the originating operators cord circuit for receiving a disconnect signal from the called subscriber, and releasing means controllable by the trunking operator for automatically disconnecting between the trunking operator and the called subscriber.

Q. A telephone system comprising an originating operators' cord circuit, a relay controllin the continuity of said cord circuit, a truu ing operators cord circuit, a trunk line connecting the two cord circuits, an automatic switch, means for manually extending connection from the trunking operators cord circuit to s'aid automatic switch, means by which the trunking operator controls the operations of saidautomatic switch, a relay associated with thetrunking operators cord circuit, and an energizing circuit including both of said relays in series with one side of the trunk line between the two COl'Cl circuits.

3. A telephone system comprising an originating opcrutofs cord cirruit, a trunk line adapted to be connected therewith provided at one end with a trunking operators cord circuit, a relay associated with said trunkin operatefs cord circuit, a signal controlled by said relay, an automatic switch, a trunk line leading from the trunking operators cord circuit to the automatic switch, means at the trunking operators position for controlling said automatic switch to find the called line, means for energizing said relay to display said signal when a connection is made between said trunking cord and trunk, and means for deu-er izing said relay upon the response of the ca led subscriber.

4. A telephone exchange system comprising subscribers lines, and means for trunking calling lines into connection with called lines, said means including originating and trunkin operators cord circuits for extending the rst portion of the trunking connection, a plurality of selectors and a connector for completing the trunking connection to the called subscribcrs line, means at the trunking operators position for controlling the operations of the selectors and connector, and a: signal at said trunking o-perators cord adapted to be displayed when a connection is made between said cord and one of said selectors and adapted to be extinguished upon the response of the called subscriber.

5. In an automatic and manual telephone exchange system, a trunking operators cord circuit terminating at one end in a multiple j aclr and. at its other end in a plug having a voice-current conductor normally connected to non-grounded battery, a front supervisory relay and a back supervisory relay, a pair of signals controlled thereby, the front supervisory relayadapted to energize as soon as an originating operator plugs into the jack to revent the front supervisory signal from ligiiting, a trunk provided with an automatic switch at the end thereof, means causing. the back supervisory relay to energize as soon as the trunking operator plugs mto said trunk leading to an automatic switch for causing the back supervisory si 'nal to be displayed, the back supervisory re ay being adapted to remain energized after con nection is made with the called line, means causin it to de'energize as soon as the called subscn or answers, whereb the back supervisory signal is extinguis 1ed, and means whereby non-grounded battery potential is removed from said voice-current conductor while said relay is energized, as set forth.

6. In an automatic and manual telephone exchange system, automatic switches, quick and slow acting relays 114: and 115 controlling the release of said switches, a cord circuit J, a push-button a for cutting oil the ground from the quick and slow acting relays 114 and 115, so that afte a connection has once been set up the trunking operator at J may change cords without initiating the release, substantially as set forth.

7. In an automatic and manual telephone exchange system, a subscribers line, a trunking operators cord circuit, a back supervisory relay therefor, a first selector, :1 second "selector and a connector, a rotagy line relay for each of said selectors an connector, and means for energizing said back supervisory relay in series with said rotary line relays, as set forth.

8. In an automatic and manual telephone exchange system, manual and automatic substations, an originating operators oord circuit, a trunking operators cord circuit, a back-bridge relay 113 at said originating operators cord circuit, a signal lamp con trolled thereby, a back supervisory relay 168 at the trunking operators cord circuit, a

signal controlled thereby, and a connector F having a backwbrid e relay 78 controlled from an automatic su station, which relay in turn controls the back supervisory relay 168 at the trunking operators cord circuit, which relay 168 when energized is adapted to deenergize the back-bridge relay 113 at the originating operators cord circuit, thereby displaying the signal controlled thereby, and said relay 168 adapted when energized to display the signal associated therewith.

9. In an automatic and manual telephone exchange system, manual and automatic substations, an originating operators cord circuit, a trunking operators cord circuit, a back-bridge relay 113 at said originating operators cord circuit, a signal lamp controlled thereby, a back supervisory relay 168 at the trunking operators cord circuit, a signal controlled thereby, a connector F having a back-bridge relay 78 controlled from an automatic substation, meanswhere by the connector back-bridge relay 78 energizes as soon as connection is made with the called line, the back-bridge relay 168 of the trunking operators cord circuit being therey energized to cause a display of the signal controlled thereby, the signal at the originating operators cord circuit being displayed at the same time, and means whereby when the called subscriber answers at the automatic substation the connector back-bridge relay 78 and the trunking operators back signal relay 168 denergize, thus retiring the signal lamps at the trunking and originating operators cord circuits.

10. In an automatic and manual telephone exchange system, a manual subscribers station A, an originating operators cord circuit C with a front supervisory lamp 177 and a back supervisory lamp 110, a trunking operators cord circuit J with a front supervisory lamp 172 and a back supervisory lamp 171, an order wire 0, a connector switch F with a back-bridge relay 78, an automatic substation A, means whereby when the manual subscriber A removes his receiver the front supervisory lamp 177 is displayed at the cord circuit 0, means including the order wire 0 whereby the manual operator at C may signal the trunking operator at J and place an order for connection to an automatic subscriber, and whereby the trunking operator at J may assign to the operator at G a trunk terminating in the cord circuit J, means whereby when the operator at C plu into the trunk leading to the cord circuit :J the front supervisory lamp 102 of the cord circuit J is displayed, trunks allotted to the trunking operator at J and terminating in an automatic exchange, means whereby when the trunking operator at J plugs into one of said automatic trunks the back supervisory lamp 171 of the cord circuit J is displayed, means whereby at the same time the back supervisory lamp 110 of the cord circuit C is displayed, means allotted to the trunking operator at J for establishing an automatic connection including a selector D and a selector E and a connector F, means whereby the back supervisory lamps 171 and 110 remain displayed after the trunking operator J plugs into the automatic trunk and until the called subscriber answers, means whereby when the called subscriber answers said back supervisory lamps 171 and 110 are retired, means whereby when the manual sub scriber at A hangs u his receiver the front supervisory lamp 1 7 is again displayed, means whereby when the automatic subscriber at A hangs up his receiver the back supervisory lamps 171 and 110 are again displayed, giving the originating operator at C a disconnect signal by means of lamps 177 and 110, means whereby when the originating operator at C disconnects from the trunk circuit J the front supervisory lamp 172 is also displayed, giving the trunking operator at J a disconnect signal, and means whereby when the trunking operator at J disconnects from the automatic trunk leading to the automatic exchange a release of the automatic switches is automatically accomplished.

11. A telephone system comprising an automatic switch, a trunk line leading thereto, a spring jack for the other end of said .trunk line, a normally closed low resistance ing operator for automatically extending 1 connection fromthe trunking operators position to the called line, operated by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, means at the originating operators cord circuit for receiving a disconnect signal from the calling subscriber, means at the originating operators cord circuit for receiving a disconnect signal from the called. subscriber, and releasingmeans controllable by the trunking operator for automatically disconnecting between the trunking operator and the called subscriber.

13. A telephone system comprising an originating operators cord circuit, a relay controlling the continuity of said cord circuit, a trunkingo'perators cord circuit, a trunk line connecting the two cord circuits, an automatic switch operative by vertical motion from one level to another to select groups and. by rotary motion in any selected level to connect with a line therein, means for manually extending connection from the trunking operators cord circuit to said automatic switch, means by which the trunking operator controls the operations of said automatic switch, a relay associated with the trunking operators cord circuit, and an energizing circuit includin both of said relays in series with. one si e of the trunk line between the two cord circuits.

14. A telephone system comprising a trunk line terminating at one end in a trunking operators cord circuit, a relay as sociated with said cord circuit, a signal controlled by said relay, an automatic switch operative by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, a trunk line leading from the trunking operators cord circuit to the automatic switch, means at the trunking operators position for controlling said automatic switch, means for energizing said relay to display said signal when a connection is made between said trunking cord and trunk, and means for denergizing said relay upon the response of the called subscriber.

15'. A telephone exchange system comprising subscribers lines, and means for trunking calling lines into connection with called lines. said means including originating and trunking operators cord circuits for extending the first portion of the trunking connection, a pluralit of selectors and an automatic connector or' completing the trunking connection to the called subscribers line, operative by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, means at the trunking operators position for controlling the operations of the selectors and connector, and a signal at said trunking operators cord adapted to be displayed when a connection is made be tween said cord and one of said selectors and adapted to be extinguished upon the response of'thc called subscriber.

16. A telephone system comprising an automatic switch operative by vertical motion from one level to another to select gronpsand by rotamotion in any selected level to connect wit a line therein, a trunk line leading to said switch, a spring jack for the-other end of said trunk line, a normall closed low resistance bridge across said trun line between the jack and the automatic switch, a normally open connection between said bridge and the ground, a relay for opening said bridge, a relay for closing said ground connection, and an operators key for opening said ground connection.

17. In an automatic and manual telephone exchange system, a trunking operators cord circuit terminating at one end in a multiple jack and at its other end in a plug having a voice-current conductor normally connected to non-grounded battery, means including an automatic switch for extending a. connection. from said cord to a called line, a front supervisory relay and a back supervisory relay, a pair of signals controlled thereby, the front supervisory relay adapted to energize as soon as an originating operator plugs into the jack to prevent the front supervisory signal from lighting, means causing the back supervisory relay to energize as soon as the trunking operator plugs into a trunk leading to said automatic switch for causing the back supervisory signal to be displayed, the back supervisory relay being adapted to remain energized after connection is made with the'called line, means causing it to deenergize as soon as the called subscriber answore, whereby the back supervisory signal iscaused to light, and means whereb nongrounded battery potential is removed from the voice-current conductor when said, relay is energized, said automatic switch operative by one motion to select groups and by a second motion to connect with a line in a selected group.

18. In an automatic and manual telephone exchange system, subscribers lines divided into groups, a trunking operators cord circuit, a back supervisory relay therefor, a second selector, a third selector and a connector, a rotary line relay for each of said selectors and connector, and means for energizing said back supervisory relay in series with said rotary line relays, said connector operative by vertical motion from one level to another toselect groups and by rotary motion in any selected level to connect with a line therein, as set forth.

19. lin an automatic and manual telephone exchange system, subscribers lines divided into groups, manual and automatic substations, an originating operators cord circuit, a trunking operators cord circuit, a back-bridge relay 113 at said originating operators cord circuit, a signal lamp con trolled thereby, a back supervisory relay 168 at the trunking operators cord circuit, a signal controlled thereby, and a connector F having a back-bridge relay 78 controlled from an automatic substation, which relay in turn controls the back supervisory relay 168 at the trunki-n operators cord circuit, which relay 168 when. energized is adapted to deenergize the back-bridge relay 113 at the originating o-perators cord circuit thereby displaying the signal controlled thereby, and said relay 168 adapted when energized to display the signal associated therewith,

said connector operative by vertical motion from one level to another to select groups and by rotary motion in any selected level. to connect with a line therein.

20. In an automatic and manual telephone exchange system, subscribers lines divided into groups, manual and automatic substations, an originating operators cord circuit, a trunking operators cord circuit, a backbridge relay 113 at said originating operators cord circuit, a signal lamp controlled thereby, a back supervisory relay 168 at the trunking operators cord circuit, a signal controlled thereby, a connector F having a back-bridge relay 78 controlled from an automatic substation, means whereby the connector back-bridge relay 78 energizes as soon as connection is made with the called line, the backbridge relay 168 of the trunking operators cord circuit being thereby energized to cause a display of the signal controlled thereby, the signal at the originating operators cord circuit being displayed at the same time, and means whereby when the called subscriber answers at the automatic substation the connector back-bridge relay 78 and the trunking operators back signal relay 168 denergize, thus retiring the signal lamps at the trunking and originating operators cord circuits, said connector operative by vertical motion from one level to another to select groups and by rotary motion in any selected level ,to connect with a line therein.

21. In an automatic and manual telephone exchange system, a manual subscribers station A, an originating operators cord circuit C with a front supervisory lamp 177 and a back supervisory lamp 110, a trunking operators cord circuit J with a front supervisory lam 172 and a back supervisory lamp 171, an order wire 0, a connector switch F with a back-bridge relay 78, said connector operative by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, an automatic substation A, means whereby when the manual subscriber A removes his receiver the front supervisory lamp 177 is displayed at the cord circuit C, means including the order Wire 0 whereby the manual operator at C may signal the trunking operator at J and place an orderfor connection to an automatic subscriber, and whereby the trunking operator at J may assign to the operator at O a trunk terminating in the cord circuit J, means whereby when the operator at C plugs into the trunk leading to the cord circuit J the front supervisory lamp 102 of the cord circuit J is displayed, trunks allotted to the trunking operator at J and terminatin in an automatic exchange, means whereby w en the trunking operator at J plugs into one of said automatic trunks the back supervisory lamp 171 of the cord circuit J is displayed, means whereby at the same time the back supervisory lamp 110 of the cord circuit C is displayed, means allotted to the trunking operator at J for establishing an automatic connection including a selector D and a selector E and said connector F, means whereby the back supervisory lamps 171 and 110 remain displayed after the trunking operator J plugs into the automatic trunk and until the called subscriber answers, means whereby when the called subscriber answers said back supervisory, lamps 171 and 110 are retired, means whereby when the manual subscriber at A hangs up his receiver the front supervisory lamp 177 is again displayed, means whereby when the automatic subscriber at A hangs up his receiver the back supervisory lamps 171 and 110 are again dis layed, giving the originating operator at C a disconnect signal by means of lamps 177 and 110, means whereby when the originating operator at O disconnects from the trunk circuit J the front su ervisory lamp 172 is also displayed, giving t e trunking operator at J a disconnect signal, and means whereby when the trunking operator at J disconnects from the automatic trunk leading to the automatic exchange a release of the automatic switches is automatically accom lished.

22. n a telephone system, a callingand a called subscribers line, an automatic connector switch for establishing connection with a called line, means including a plurality of operators circuits for extending a connection from the calling line to said connector switch, and means consisting of signals by which the originating operator supervises the connections thus established, each signal being adapted to be displayed when the corresponding receiver is hung up at the substation.

23. In an automatic and manual tele hone exchange system, subscribers lines divided into groups, a manual operators trunking cord, means operative by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, electrically controlled release equipment for said means, release circuits for controlling said equipment, energized quick and slow acting relays for controlling the release of said means, and means including a push button for rendering the release circuit inoperative so that after a connection has once been set up the trunking operator may change cords without initiating the release.

24:. A telephone system comprising an originating operators cord circuit, a trunk line adapted to be connected therewith provided at one end with a trunking operators cord circuit, a relay associated with said trunking operators cord circuit, a signal controlled by said relay, an automatic switch, a trunk line leading from the trunk ing operators cord circuit to the automatic switch, an impulse sender at the trunking operators position for controlling said automatic switch to find the called line, a circuit for energizing said relay to display said signal when a connection is made between said trunking cord and trunk, and a switch for deenergizing said relay upon the response of the called subscriber.

25. A telephone exchange system comprising subscribers lines, and trunking circuits for trunking calling lines into connection with called lines, said trunking circuits including originating and trunking operators cord circuits for extending the first portion of the trunking connection, a plurality of selectors and a connector for completing the trunking connection to the called subscribers line, an impulse sender at the trunking operators position for controlling the operations of the selectors and connector, and a signal at said trunking operators cord adapted to be displayed when a connection is made between said cord and one of said selectors and adapted to be extinguished upon the res onse of the called subscriber.

26. telephone system comprising a trunk line terminating at one end in a trunking operators cord circuit, a relay associated with said cord circuit, a signal controlled by said relay, an automatic switch operative by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, a trunk line leading from the trunking operators cord circuit to the automatic switch, an impulse sender at the trunking operators position for controlling said automatic switch, a circuit comprising the called subscribers line for energizing said relay to display said signal when a connection is made between said trunking cord and trunk, and a switch controlled by the called subscriber for controlling said circuit to deenergize said relay upon the response of the called subscriber.

27. A telephone exchange system comprising subscribers lines, and trunks less in number than the subscribers lines for trunking calling lines into connection with called lines, said trunks including originating and trunking operators cord circuits for extending the first portion of the trunking connection, a plurality of selectors and an automatic connector for completing the trunking connection to the called subscribers line, operative by vertical motion from one level to another to select groups and by rotary motion in any selected level to connect with a line therein, an impulse sender at the trunk ing operators position for controlling the operations of the selectors and connector, a signal at said trunking operators cord, a circuit for controlling said signal so that the same is displayed when aconnection is made between said cord and one of said selectors and retired upon the response of the called subscriber.

28. In a telephone system, a calling and a called subscribers line, an automatic connector switch for establishing connection with a called line, trunking circuits less in number than the lines including a plurality of operators for extending a connection from the calling line to said connector switch and a signal for the originating operator for supervising connections thus established, a circuit for said signal, said signal being under the control of the subscriber on the line called through the medium of said circuit whereby the signal is displayed to indicate that the called subscriber is through talking.

29. In a telephone exchange system, the combination with a plurality of subscribers lines terminating in different central ofiices, trunk lines of the two and three conductor type, automatic selector switches, sending mechanism at one of said oiiices adapted to direct said switches to intercon- --nect said subscribers lines by means of said trunk lines, an established connection including both two-conductor and three-conductor trunk lines and leading through a plurality of offices, the trunk lines extending to the controlling oflice and from the controlling oflice to another office through which the calling line is extended being of the twoconductor type, and signals at said controlling office for supervising connections.

Signed by us at Chicago, Cook county, Illinois, this 17th day of April, 1907.

WILSON L. CAMPBELL. TALBOT G. MARTIN. Witnesses:

J. NonBY, ARTHUR B. SPERRY.

Copies 01' this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0."

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