US2369578A - Telegraph station selector system - Google Patents

Description

Feb- 13., l945- F. s. KINKEAD ET'AL 2,369,573

TELEGRAPH STATION' SELECTOR SYSTEM Filed July so, 1941 4 sheets-sheet 1` |||II| Il -A l n l W n. i NQ al l* TIT 4 lllll 5. KIN/(EAD J KRE'CEK .Afro/wir /NVE N7' ORS .1.... N .m N tw A Il -ILM i S m8." l l .ll 1 l l 1 @Nk m13 lr m .el NH M/Q A me @S zotw *Qfkll Feb- 13, 1945- F. s. KINKEAD ET AL TELEGRAPH STATION SELECTOR SYSTEM 4 Sheets-Sheet 2 Filed July l3C), 1941 ,es. /r/NKEAD c A. KREcE/r /NvEA/roRs ATTORNEY Feb 13, 1945. F. s. KINKEAD ETAL 2,369,578

TELEGRAPH STATIQN SELECTOR SYSTEM Filed July 30, 1941 4 Sheets- Sheet 4 l -I m.

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f "2 Q 0 ,N

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.Sages t be transmitted.

Patented Feb. 13, 194s auatic' l'.lELEGrRAPHv STATION SELECTOR SYSTEM y Fullerton S; Kinkead, New York, and Joseph A.

` Krecek, New Rochelle, N. Y., assgnors to Bell Telephone Laboratories, Incorporated, Newv York, N. Y., a corporation of New Yorkv Application `my 3o, 1941-,ser'ia1No. 404,602

' a (crus-4) 2,5 Claims.

This invention relates Ato a telegraph' system, and particularly to a system having a plurality of ytelegraph stations to be interconnected through the medium of switching apparatus located in a central oiice station.

Anobject of the invention is to provide a` call destination indicator device under'the control of a station and .operable in different ycharacteristic ways tov indicate different destinations of meslAnother object ofthe invention isto'ope'rate the call destination indicator device in different characteristic ways over a communication chan- `nel andinaccordance with the ccnditionof the communication channel as determined at av re- .mote station on the channel.

Another object .of the invention is to control `from a central 4oiiice switching station the disablement oftthe call destination indicator device by terminating the communication line condition established at the remote 'station whichY eiected characteristic. operation of thercall destination indicator device. A

A- further object of*` the invention isto provide starting means for a transmitter at a remote station controlled from a central ofce switching sta.- tion and to, provide stopping means for the transmitter controlled 'by a signal generated bythe transmitter; which signal also controls a disconnect indicator at vthe vcentral yofiice switching station. 1 The invention featuresxmeans .'at the` central oiiice stationforplacing a call destination indiator deviceunder theicontrol cfa communication channel-extending tothe remote station to which the call destinationiindicator pertains.

Theinvention also featuresa self-interrupting relay system located at-the `remote or call initiating` station and -arranged to be set lin Aoperation under local control at vthat station for establishing alternate marking and spacing conditions on the commnicationchannel whereby to cause intermittent operation ofthe call destination indicator device associated with'the communication channel.y o

The invention also features a lamp employedas a call destination indicatorv device and arranged .belonging to a different class of stations which vdiierence may be characterized by physical attributes of Lthe station or by message traiiic conditions, or both. y One of the stations, which may be of either class, may be intimately associated with the central oiiice switching station, or all stations may be remote from the central office station. a

' The centralr voffice station is provided with switching means for interconnecting any two or more ofthe 'telegraph stations and is also provided with at least one operatorsset for aiording intercommunication between an operator and the telegraph stations in the system, such as for informing the operator of the destination of a message to be transmitted.

At thev central oi'iice switching station, call destinationindicator lamps are associated with certain of the communication channels, and in the 'preferred' embodiment of the invention, these channels extend to vthestations of one class, and

, theother class comprises only-one station, or if it'includes more than one station there is no distinction between them as regards message destination indications. Each of the telegraph stations having a communication channel with which a call destination indicator lamp is associated is -provided with means for causing its call destination indicator lamp to be illuminated steadily or to flash. One of these operative conditions of the lamp indicates a-call directed to another station ofthe same class and instructs an operator at the ,switching station to answer the all, to ascertain thefdestination of the vmessage which is to be v*transmitted and to interconnect the communication channel of the calling and called stations by means of switching apparatus. Operation of the indicatorilamp in the other. of the two characte'ristic ways of operation directs theoperator at the switching station to interconnect the communication channels of thefcalling station vand of the station or stations of the other class by r means of thek switching apparatus without an- 'swering the callor inquiring as to the destination, since they particular mode of operation of the lamp indicates the destination.

Each of the stations 'of the class which controls call indicator .lamps is provided with a storage transmitter which, inthe preferred embodiment of the invention, is a perforated tape transtransmitter at the end of the message, fori stopping the transmitter independently of any mechanical transmitter arresting `means;such as a tape tension responsive device. Each of the communication channels extending from the staf tions that are provided withA the 'storage transmitter may be generally similar to the tape transmitter shown in Patent 2,055,567 granted A. September 2.9, 1936, to jE. F. Watson.v The keyboard transmitter |02 and receiving printer |03 V,may be a combination unit wherein printing is performed on a tape, as exemplied in Patent t .1.7l,5.3.3 .granted February 4. 1930. to S. Morton et al. o r may be of the type in which printing i is accomplished on page width paper, as in Patmitters have disconnect indicator lamps .asso

ciated therewith at the central office switching en; Locales granted April 18, 1933, to s. Morton et al. The disclosures of the three patents above identified are incorporated herein by reference station, and the signal whichcauses arrestment i' of the transmitter at the end of a message ,also

causes the disconnect signal lamp to be' operated .to Serve as au instruotiori to the operator at the oeiitral edite station to disestablish the communieative eoiiiieotiou between the Calling .and called stations lov restoring, Jthe switching apparatus to pitite svvitoiiiiie station may be provided with sigpal respoiisivesvvitoliipe mechanism for solea-l tiveiv determining vviiioii of two or more telegraph receivers.. pertain .oi which may be iooated .et p tempt -iroiu the signal responsive Svvitoliiiiemetti shall reoeive .a message to te transriiitted from oiie of the other telegraph stations in the system, With this arrangement e primary destination .of a. message iiidioeted bv .the pall destination indioator lampaiid ,a solo.- ordiiiate .destination is indicated lovsigpais pref pedine the message Wiiioh do not require any action ou the part oi the operator .at theoem trai. oiiiee .switoliinc station l For a eoiiipletey understanding o f` the ,iiiveri-v tion reference may be had to the iollowinc de.- tailed description to. be interpreted in the licht of the accompanying .drawings wherein:

- Figiis a schematic .vievv showing, somewhat iu detail., a telegraph station of the local loop typejcoiiiieotedto a repeater. and in diagram.- .matio form three other stations of the same class andi one station of different class;

. Fis.-2 ,is .a sehematioview Showing, in detail.

at a central office switching Station, a closed -tra-l ofdce switching station, key switching cir.,-

cuits respectively connected to the control cir,- cuts of Fig.` 2 and a vkey switching kcircuit for an .operators telegraph set;

. Fig. 4 is a schematic view showing an opera: torsset connected tothe operators switching key circuit including operators transmitting and receiving apparatus; and

Fig. 51s a diagrammatic View showing how the previously identified iigures ofthe drawings may be arranged relativeto each other toform a corna plete communication system. in accordance with the. invention.

Referring nowto. the `drawings,land particug larly to` Eig. l, the referenceV numerals ll, I2 and I3. designate three telegraph stations which may be identical and only one of which, the stationl'l, isshown in detail. The principal come municatlon elements of the station are the tape transmitter |Il.|-, the keyboard transmitter ||l2 andthe, receiving printer |03 indicated sym:

rbolically.. by a selectorr magnet. lThe tape transf.

as a partof this specification.

'lhe tape transmitter I|l|` includes perforated tape controlled contacts |04 which set up code combinations on the seg-ments of a segmented ring which is traversed by brushes of a distrib` utQl arm l v|16 which impresses the code combina,- tiOlis .0.1.1 a continuous ring. Distributor brush arm |06 is carried by shaft |01 which is driven .by motor. I through friction clutch |09 and gears l!! under the control yof a start cam ||2 controlled by start.. magnet |l3. rIhe energizing circuit for start magnet H3 includes 'tape tension responsive contacts YI |14, manually operable switch H6 and `irontcontact and armature of normally deenergized relay lll. The continuous ring of the distributor is connectedfto conductor l I8 which represents one side of the communication channel loop with which the station is directly associated and the stop segment of the distributor and one side of. each of the pairs of transmitting contacts |04 is connected through the operating winding of polarized line relay` H9, normally closed break contacts |2|, normally closed stop contacts of keyboard transmitter |012, normally .closed call initiating key |22, back contact and inner lower armature |23 of relay |24, normally closed contacts controlled by makevbefore-break armature 26 of relay |21, to conductor |28 which represents the other side of the communication channel loop cononected to station Perforated tape for 'storing signals to be `transmitted by tape transmitter y|| may be prepared in a keyboard perforator represented symbolically at |29. The keyboard perforator |29 may be` ofthe-type shown in Patent `1,182,179 granted May 9, 19.16, to. C. L. Krum et al. l y Assuming that the station is located within a distancef-rom its central oflice switching statien not greater than the mileage resistance limi'- tation for loop operation, the` station l|| is connected to -the central oi'ce'switchingV station through a two-relay. loop repeater I4. The loop side of the repeater vis a balanced or differential loop arrangement with the line conductor I|8 connected through the operating winding of repeater relay.v |3:|,'to the armature of repeater relay |,32,.and the line conductor |28 `connected to ground either at the station Il, or 'as shown in Fig. 1 at the repeater` I4, the system shown in Eig. 1 contemplating `a full metallic communication loop circuit between. station and repeater ld.

The spacing contacts of both of the repeater relays |31 and |32 are connected to ground and the marking contact of relay |32 is connected to grounded battery |33 through a resistor. The armature of repeater relay |32 is normally maintained in engagement. with its. marking lcontact wherebyv a closed circuit is. normally maintained 'from battery |33l through the armature of relay |32, operating` winding of" relay -|.3.|', line conductor U8, continuous ring: and stop segment of tape transmitter tlll, operatingwindingv of line relay Thus the receiving printer |03 is normally maintained` yin vthe marking condition.

-lIn addition to the 'call initiating key |22, there isv also a normally open call initiating key |36, one spring of which is connected to ground and the yother spring is connected through the winding of a slow-release relay |31 to grounded battery |38. The upper armature of relay' |31 is connected to ground and cooperates with` a front contact to complete the energizing circuit for the previously identified'relay |21 which has one end of its winding connected to battery |39 and the other end connectedto the upper front contact of relay |31. 'relay |31 cooperates with a front contact which is .connected to one end ofthe operating winding of relay. |24, the other end of which is connected to grounded battery |4|. The lower front ,contact of relay |31 is also connected to one end and |42 -comprises a vibratory system for effecting f the `alternate energization anddeenergization of relay |21.

Upon the closure of key |36 the relay |31 becomes energized and its upper armature completes the energizing-circuit for relay |21. VThe lower armature of relay |31 completes the energizing circuits for the relays |24 and |42 so that all four of the relays are now energized and attract their armatures. The armature of relay |21 rst engages its front contact and provides a ground connection for the energizing windingV of relay |24 and forthe relay |42 in parallel with the ground. connection provided by thelower armature of relay, |31. .As armature |26 of relay |21 moves into its fully operated position it opens the normally closed'contacts in the communication circuit,ethus opening the loop circuit. This causes line relay ||9 and repeater relay |3| to The grounded lower armature ofr "Upon the opening of key |36 the energizing ciricuitfor slow-release relay |31 isinterrupted and after an interval this relayreleases its armatures. The upper armature opens the energizing circuit for relay |21 and the lower armature removes one of the ground connections for the operating winding. of relay |24 and for'relay |42.

Due to the make-before-break arrangement of the contacts controlled by armature |26 of relay |21, the communication circuit is reclosed before Y armature |26 becomes disengaged from its fron't vcontact and while relays |24 and |42 areheld shift their armatures .to the spacing positions,

but'the vlower armature of relay |24,v which is grounded, engages afront contact connected to the selector magnet of receiving printer |03, so

manne printer is maintained in marking ccndition and does not respond to the spacing condition" of the communication channel. The armature |23 of relay |24 vmoves from engagement with* its back contact to engagement with lits front contaot,"which is connected to oney end of the holding winding of relay |24, the otherV end of'which is connected to the communication line on'the grounded side of the loopv between keyboard transmitter |02 and call initiatingkey |22.

'Ihus the holding winding of relay |24'is placed inthe 'communication circuit. The upper armature of relay |24, which is grounded, engages a front contact which is connected to the back contact of slow-release relay |42. The armature of relay |42, which at this time is out-of engagement with the back contact, is connected to the winding of'slow-releaselrelay |31in parallel with call;y initiating key |36. l

energized bythe ground connection afforded by the armature |26. The reclosed communication circuit now includes the holding winding of relay r|24 so that that relay remains energized and fan energizing circuit for the relay |31 from g-round through the upper armature and front 'contact of relay' |24 and through the back contactfand armature of relay |42 in parallelwith the now open call initiating key |36. Thus relay |31 becomes reenergized and in turn completes the energizing circuit for the relay |21 and slowrelease relay |42. The relay |31 also completes the circuit of the operating winding for relay |24 so that when the armature |26 of relay |21 opens the contacts in the communication circuit the relay |24 vwill not be released. The energization of slow-release relay |42 causes its armature to interrupt the energizing circuit for slow-release relay |31 which releases in the manner previously described to release the relays |21 and |42.

The relay |21 recloses the communication circuit and relay |42, releasing after an interval, again completes thev energizing circuit for therelay |31. This cycle of operations recurs to effect the alternate opening and closing of the communication circuit at the contacts controlled by the armature |26 of relay |21 until the system is disabled in a manner which will be described later.

The station is provided witch means forl starting and stoppingthe tape transmitter |0| under the control of signals on the communication channel. yFor controlling the mechanism which starts and stops the tape transmitter |0|, the receiving printer |03 is provided with normally open contacts |46 and |41 controlled by function members |48 and |49, respectively. The manner in which contacts may b controlled by function members of a receiving printer is fully disclosed in the Morton et al. Patent 1,904,164. One of the contacts |46 is connected tovground and the othercontact is connected to one end of the winding of`a relay |5|, the other end of which i's connected to grounded battery |52. A set of manually operable normally open contacts |53 is connected in parallel with the contacts 46 to provide for operation of relay |5| under manual control. The lower armature of relay l|5 I, which is also connected to battery |52, isenim" armature to complete 'the energizing circuit for start magnet I|3 if tape tension responsive contacts H4 and manually operable switch H6 are then closed. Start magnet: rl I3 operates to Withdraw a lever from blocking relation to start cam |l2, sov that distributor shaft |0'l` of tape transmitter is released for rotation.

' A' holding circuit for the relay |5| is completed from a front contact through the upper armature ofthe relay, armature and back contact of arelay |54 and normally closed manually operable contacts |56 to ground. The relay |54 has one end of its winding connected to. battery |51 and the other end connected to one of the' contacts |41, the other contact being connected to ground. Upon the operation of contacts |41 by function member |49 of the receiving printer, the energizing circuit of relay |54 is completed and the relay attracts its armature to interrupt; the holdcircuitffor relay The. relay |5|, upon releasing its lower armature, interrupts the energizing circuit for the relay ||1 which interrupts the circuit for the start magnet I. |3` of the tape transmitter |.0l whereby the armature of the start magnet arrests start cam |2 and thus the transmitter |0| is stopped. The manually operable key |5tl is operable to provide local manual control of the releasey of. the holding circuit for relay |5I, whereby the transmitter |0| may be stopped independently of the contacts |41. The relay |51 is provided with an armature |50 which cooperates with a fron-t contactv to short-circuit the transmitting contacts; of the keyboard transmitter |02 so that the keyboard transmitter may not be operated to interfere with the transmisf sion of signals from the tape transmitter IM when relay |5,| has been energized to set in opera-- tion the tape transmitter.

The operating winding of the relay |32 which repeats signals. transmitted tothe station has one end connected to battery |33 and thez other.

end connected by conductor to the left-hand armature of a relay 202 of acontrol circuit. 2|. forming, part ci the central cnice switching station and permanently associated with the; telegraph` station through the repeater` i4. The control, circuit. 2| and repeater |4 are similar to control circuits and repeaters disclosed in Patent No, 2,280,292 granted April. 21, 1.942, to F; S. Kinkead et al. `The disclosure oi the Kinkead et. al. patent is incorporated herein by reference asa part of this. disclosure. Conductor 20| is also connected to the right-hand back contact of relay 20.2. The marking contact of repeater relay |31 is connected to the left-.hand front contact of relay202 by conductor 203 and the armature of relay t3.|. isiconnected through conductors. 204

and 206 to the right-hand front contact of relay 202 and through conductors 20,4, 201 and the winding of relay 208 to a potentiometer which comprises the resistors 209 and 2| l., One end of the potentiometer. is connected to grounded4 battery 2|2 and; the: other end of the potentiometer is connected to ground.

Upon the opening of, the communication circuit between station and. repeater |4 such as 'directly by the operation of call initiating key |22, or indirectly through the operation; of call its front contact. The amature of relay 208 is grounded and the back contact is' connected to one side of a condenser 2|3, the other side of which is connected through a resistor to ground. The front contact of relay 200 is connected by conductor 2|4 to the inner right-hand front contact of a relay 2|.||. The side of condenser 2|3 which is connected to the back contact of relay 208 is also connected through resistor 225 and conductor 224 to battery 226.

Upon theoperation of relay 208 the short crcuit across' condenser 2 i3 afforded by the ground at the armature of relay 208 is removed, so that charging current for the .condenser may flow through resistor'225 from battery 226. When condenser 2|3 is short-circuited the grid of tube 222 is biased suiciently negatively'to render tube 222 non-conductive. The capacity of 'condenser 2 |3 is suchthat in an interval preferably substantially as long as but not longer than a permutation code combination they condenser 2|3 will become charged and raise the potential' of the grid of tube 222 suiciently to causev the tube to become conductive. The reason for the-timing circuit consisting of the condenser 2|3' and discharge tube 22.2 is to prevent. the relay 208 from eiecting a control condition as it. responds to spacing impulses occurring during normal signaling.. The plate circuit of tube 222' includes a relay 2121' which becomes energized when the tube v2122 becomesy conductive and attracts its armature into engagement, with its grounded front contact.

The relay 221' completes a` circuit` from ground through its front contact and armature, outer right-hand armature and back contact of a relay 228, conductor 2:29, inner left-hand armaturey and back. Contact` of al relay 23|, conductor 232 extending in-to Fig. 3, call destination indicator lamp;Y 30|., conductor 302 extending back` into Fig. 2 andA winding of relayl 2l8r to grounded battery 226. Relay 2|'8 thus becomes energized through the call destination indicator lamp4 30|, and a holding circuit; for the. relayI 2|8. is established from ground, at the right-hand' inner armature otrel'ayv 22.8 through the back contact of relay 220,. conductor 233', conductor 23'4, right-hand armature and back Contact of.' `relay 23|, conductor 236', front Contact and left-hand `armature oi'f relay N8, conductor 232 extending into Fig. 3, call destination indicator lamp 30 conductor 302 extending back into Fig. 2, andl winding of" relay 2 |81 to grounded battery 220. The inner righth-and 'armature of relay 218 completes a second holdin-g circuit for' the relay 2:!8v from the grounded armature of relay 208 through thefront contact of that relay, conductor 214, inner righth-and front Contact and; armature of relay 2.|'8`. windingr of the relay to grounded'. battery 22.6, which holding circuit parallels. the. first holding circuit but does not include the call destination indicator lamp 30|'. As longas. the relay 200 refmains operated the lamp 30| is short-circuited by the second' holding circuit for the relay 2.|3 and' is not operatedr The outer right-hand armature ofl relay 2I.8. cooperates with. ai grounded front contact. to complete a circuit from the ground, through the. front contact andr armature, conductor 231, key 40,1 at an operatorsa position (Fig, 41 alarm device 402 to' grounded. power source 403. The alarm, device 4202 .is operated over this circuit toV call: the, attention off an operator to the fact that. a call destination indicator lamp is about to be operated', indicating thatfa connection through the switching apparatus, is desired.

Upon the reclosure of the communication circuit between. `stationY and the -repeater |4,

,Whether by closure of key |22 or by thedeen- I ergization of relay |21 incident tothe operation of the vibratory relay system, the armature of repeater relay |3| will be restored to marking position vto-disconnect ground'from the relay 208. Upon'the release of the armature of relay 208, the second`holding circuit for relay 2|8 is interrupted, leaving only the first holding circuit for |36 the relay |21 at 'station will be alternately energized and `deenergized to open and close alternately the communication circuit between station :'|I and repeater I4. The re1ay,208will respond. to these interruptions of the communication circuit to supplement the first holding circuit of relay 2I8 l with the second holding circuit. Each time this occurs the call destination indicator lamp 30| will be extinguished due to a shunt condition so that under the controly of the vibratoryy relay circuit of station I the lamp 30| will be caused to flash.

The stations with which the telegraph station I I may desire to communicate are the stations I2, |3, I5 and I6 in Fig. 1. As previously stated, stations I2 and |3 are assume-d to be identical with station II. Station I5 is-assumed to include app-aratus identical with that shown at station `Il and` in addition thereto, a receivingonly printer |6|, represented symbolically by the selector'magnet enclosed in the broken `line rectangle, connected to the station I6. w f-"Inaccordance with the present invention, station.|6 is presumed to differ significantly from the other telegraph stations in the system. It

' need not dierphysically from the other stations but may differ functionally, such as, for example, being the recipient of a large vpercentage of the messages originating at other .stations in the system. In conformity with thelatter distinction between station I6 and the other telegraph stations, the station I6 has been shown as a receiving-only station. Furthermore, it has been shown as including a signal responsive selector mechanism whereby a message directed to the station 6 may be recorded at that stationormay be recorded atthe receiving-only printer |6I. associated origin at the station I6. However',- by providing a.: repeater of this type the station |6 may at any timev be converted toa full sending and 'receiving station by theaddition of transmitting apparatus without modification of` the repeater 20.

.The signal responsiveswitching selector mechanism which has been shown diagrammatically at station I6 in Fig. v1 may be of the type .disclosed in Patent 2,120,235 granted June 14, 1938, to'J. F. Beattie et al., and the disclosure of this patent isincorporated herein by reference as a part of the present disclosure. The communication'loop comprising the conductors |62 and |63 extending `between therepeater 20 and the station |6 ,includes the selector. magnet |64 of vthe switching :selector mechanism |66, the normally closed contactsy in series controlled in makebefore-break manner by the left-hand'armatures of relay` |61A and the normally closed contact in series .controlled in make-before-break manner bythe left-hand armatures of relay |68. The selector magnet of the receiving-only printer f|6| located at station |5 is connected between the left-hand armatures of` relay `|68, and the selector magnet of -the receiving-only printer1j|69 located at stationvv I 6 is connected between the left-hand armatures'of relay |61. i

The selector magnet|64 controls, among other thingsthe selection and operation ofseveral `selectable members'Hl, |12 and |13. The selectable members |1.| and |12A operate normally open ycontacts |14 and |16, respectively, and the rselectable member |13 operates normally-closed contacts |11. One ofthe contacts |16 is con-` nected to ground` and the other is connected 'to one end of the winding of relay |61,-the other end of which is .connected to grounded ybattery |18. Upon the closure of contactsy |16 `and energization of relay |61, a holding circuit for the` relay is established from ground through the normallyl closed contacts |11 and through the right-hand armature and front contact of relay |61 and its winding to grounded battery |18. The-left-hancl armatures of relay |161 are operable to insert the selector magnet of receivingonly printer |69v in the loop circuit of station |6, and ythe,make-before-break operation of the contacts controlled byV the armatures "assures that the additionof'the selector magnet of printer |69 to the loop fcircuitis' accomplished without interruption of the loop circuit.

'In asimilar manner the' contacts |14 are operable to complete, to grounded battery |19, the energizing circuitforrelay 68, for which a holding'circuit is completed through the right-hand armature landfro'nt contact. of -the relay from ground at the normally -closed contacts 11 .to

battery "|19," The' 'left-hand armatures of relay |68' are operable `to ,insert the selector magnet' of receiving-only printer'l |6I` in the loop circuit. Either orboth ofthe printers |6| and |69 may beconnected into the lloop circuitby the selective operation ofy either or both 'of theA sets of contacts |14`,and |16" in'r'esponse to their assigned code signals'. When the transmissionof messageI material to either or both of the receiving-only printers |6| and .|69 Ahas been completed and it is I4desired to remove thoseyprinters A'from theloop circuit, this may be uzcomplished by the transmissionof the code signal which effects the selectionand'. operation'of selectable member |13. "I'h'e'se'lectable member |13 4opens contactsil11, therebyinterrupting the holding circuits for eitheiioflthe relays-f1.6.1and |68 or both, if bothare operated, and printers |6| and |69 are disconneotedffrom .the loop circuit, which is maintained 'uninterrupted during the disconnecting operation by the make-before-break arrangement of they contacts controlled by the relay armatures, and `is maintained uninterrupted thereafter by the series arrangement oi.' thecontacts.

Three conductors correspondingA to the conductors 20|, 203 and 204v extend from the repeaters I1, I8, I9 and 20 to - control circuits 22, 23, 24` and 25, respectively, which are similar to the control circuit 2| (Fig. 2). is` will be more fully set forth hereinafter, the control circuit 2| affords two-way communication in accordance with half duplex principles and the control circuits 22, 23, 24 and 25 accommodate similar communication. As in the case of the repeater 20 the control circuit 25 accommodates transmission which station I 6 cannot initiate, since station is presumed to be a receivingonly station. However, the control circuit 25 requires no modiiication in the event that station I0 is converted to a transmitting and receiving station by the addition of transmitting equipment. In this 4connection it is to be noted that station I6 does not require a call destination indicator lamp at the switching station nor does it have occasion to operate the call indicating I alarm at the operators position,I Accordingly,

stub conductors only are indicated at the control circuit 25 for lamp and alarm controlling circuits. It will befully apparent at this point that the telegraph stations II, I2, I3 and I5, disregarding the receiving-only printer IBI at the latter station, maybe considered as representing stations of one class and that the station |8 maybe considered as representing a different class of stations, only one of which is shown. For these two classes of cali destinations, the lamp 30| (Fig. 3) affords two call destination indications, one represented by steady illumination of the lamp and the other represented by flashing operation of the lamp. For the purpose of the following description, it will beassumed that steady operation of the lamp 30|, which results from opening of key |22 for an interval at least as long as one permutation code signal .combination, indicates that connection tov station I6 is desired, and iiashing operation of lamp 30|, initiated by closure of key |361 at station fora similar interval, indicatesthat the connection to one of the stations I2, |3 and l5 is desired.

As shown in Fig. 3 the switching apparatus, which is generally similar to that shown Vin the Kinkead et al. patent, includes a plurality of hub circuits comprising pairs of conductors, oi which six pairs have been shown,A designated by the reference numerals 303', 304, 308, 301, 300 and 309. For each of the telegraph stations Il, I2, I3, I and I6, six switching keys are provided, each key consisting of three make contacts. The six keys are individually associated with the six hub circuits andthe keys for the line extending to station I are designated by the reference numerals 3||, 3|2, 3I3, 3|4, 3|8 and 3|1. The six keys may, if desired, be arranged in pairs with either of the keys of a pair operable by a single lever movable to one or the other of tWo extreme positions from an intermediate normal Vposition oi the lever in which neither of the keys associated therewith is operated. The banks of switching keys for the stations I2, I3, i5 and I6 are indicated generally by the reference numerals 318,

to 3|1 are connected tothe two conductors comprising the' hub circuit with which'the key isdirectly associated. Of the yremaining four springs of the six switches, corresponding' ones are connected in multiple and those at the extreme right hand of each switch are connected to a conductor 321 for lconnecting thatconductor to the upper conductor of any of the six hub `circuits. The right-hand spring on the left-hand side of each switch is connected tov a conductor 328 and the two middle springs on the left-hand side of each switch are connected together and to a conductor 3 29'. The conductor 321 extends into Fig. 2 to the outer left-hand back contact of relay 228, and the outer left-hand armature of the relay is connected by conductor 24| to the right-hand armature of relay 202. The conductor 328, which also extends into Fig. Y2, is connected to one end of'the winding'of relay 202 and the other end of the winding is connected by conductor `233 to the innerv right-hand back contact of relay 228. Conductor 329 is connected to the inner left-hand back contact of relay 228 and the inner left-hand armature of that relay is connected'through resistor 242, conductor' 24.3, winding of relay 23|, and conductor 224 to grounded battery 226 Assume now that call initiating key 22 has been opened and reclosed to initiate the series of operations previously described whereby lamp 30| is steadily illuminated through locked relay 2|8 and audible alarm device 402 is operated. At the operators set, key 40| is operated manually to disable the audible alarm device 402 `and one 'of the keys 3|| to 3I1,'inclusive, is operated to connect the control circuit 2|v for station I I to an idle hub circuit. It will be `assumed that key 3|| is operated to` associate the control circuit 2| with hub circuit 303.` Conductor 321 will thus be connected to the upper' of the hub circuit conductors 303. This will be accomplished by the two right-hand .springs of the key 3| I. By the operation `of the two left-hand pairs of springs of the key, the conductors 328, 329 and the lower of the hub circuit conductors 303 will be connected together. From the ground at the inner right-hand armature of relay 228 a circuit may be'traced through the armature and back contact of that relay, conductor 233, winding of relay 202, conductor 328, left-hand springs of key 3| I, conductor 329, back contact and inner lefthand armature of relay 228, resistor 242,A conductor 243, winding of' relay 23|, conductor 224 to grounded battery 226. Thus, relays 202 and 23| lwill be energized in series.

Relay 202 is a cut-through relay and its left'- hand armature will engage the left-hand front contact to interconnect the conductors 20| and 203 extending between control circuit 2| and repeater I4. Thus the circuit of the operating winding ofrepeater relay I 32, which normally extends over conductor 20|, right-hand back contact andarmature 4oi relay 202', conductor 24|, left-hand armature and back' contact of relay 228 and conductor 321 to the several keys 3|I to 3I1, inclusive, which are normallyo'pen, is changed to extend over conductor 20|, lefthand armatureand front contact of relay 202, conductor 203, marking contact and armature of repeater relay |3I, conductor 204, to the righthand front contact of relay 202. Since by the operation of key 3||,' relay 202 has been energized, the circuit justl described is extended from the right-hand front contact of relay 202, `over the right-hand armature, conductorl 24|,flefthand armature and back contact 'of relay 228,

conductor321 and the right-hand spring of key l3H to the upper conductor of the hub circuit 303. -No other connection to this conductor of the hub circuithas yet been made but the marking condition of relay |32 is not altered. Acomplete communication circuit through the operating winding of repeater relay |32 includes sources of potential of the same magnitude and polarity at lopposite ends of the circuit so that the bat# teries are' in kopposition and no current ilows through the operating winding of the relay |32, the armature of` the relay being held` on ythe marking contact by currentv through the biasing winding. A spacing condition is established by I grounding the' remote end of the communication circuit'so thatcurren't'ows through the operating windingV of the repeater relay |32 to shift the armature to the spacing contact. The relay l32`doesnot`distinguish between a closed circuit with properly poled batteries at both ends and'an open circuit condition, and accordingly the extension of4 the circuit of the operating windingof repeater relay |32 to the hub lcircuit 303,where"the circuit is open, and the addition 'ofvthe armature and .marking contact of repeater relay |3| to `that conductive path has not changed the condition of repeater relay |32.

f Since relay 23| became energized in series with relay c 202 yits left-hand inner armature moves from back to front contact to prepare an energizing circuit for disconnect` relay 244. The right-hand armature moves from back to front contact to interrupt theholding .circuit for the 'call destination indicator` lamp relay 2I8 and .to prepare a holding circuit for, the disconnect 11el'ay 244." As theholding circuit for relay 2 I8 included the call destination indicator lamp;30|, this lamp isl extinguished and the right-'hand ,ar-` mature of relay2|8 removes the ground connection for the audible indicator 402 at the operators position'. y

' Since the steady illumination of lamp 30| indiv cated a call 'for stationIG theoperator next completes the connection through to that station.

The'switching keys `for'the st ation I6 are contained in the key bank 322 and are identifiedby v correspondto the conductors 328 and 329( thereference' numerals 33|, 332, 333, 334,336 and 331. The key which 'must be operated to connect station I6 to thev hub circuit 303 is key r33| 'and accordingly the 1operator closes this key. Relays in the control circuit 2.5 correspondingto the relays 202 and 23| are'Y operated to place'the repeater 20 in the same conditionas the repeater' .l

I4 with reference to the hub circuit 303andto prepare an energizing ,circuit for the disconnect relay .in the control circuit 25. The latter isgan idle operation, since the station y|| is a receiving only .station andis not provided With means-.for sending a, disconnect signal, nor is there any-disconnect indicator lamp to be controlled bythe disconnect relay in the control circuit 25. The

vestablishment of .a rcommunication 'path 'from the Ahub circuit is accomplished over the con# ductor 338 whichxcorresponds -to the conductor 321, and theV operationA of the relays is 'accomplished over the conductors 339 'and 34|fwhic Connections haveA now been established for the y.transmission of a messagefrom the station" that station had Placed'the perforated tape lcon'- L taining the message prior'to operating the call initiating key |22. The signal #'for eilecting the starting of the transmitter I 0I must be transmitted by the loperator at the central oflice switching station. AReferring to Fig. 4, the operatorsposition is provided witha receiving printer indicated symbolically at 406 by the selector magnet, and a. keyboard transmitter 401 which has in series therewith a break key 408; Separate closed circuit jacks 409 and 4I Il areprovided for re ceiving the plugs 4I2 and 4|3, respectively, connected tothe receiving printer 406 and the key-l boardl transmitter 401, respectively. One of the terminals of'jack 409 is connected to the marking contact of a polarized line relay 4|4, the armature of which is connected to ground, and the' other terminal of jack 409 is connected to bat-l tery 4I6. The spacing contact of line relay 4|4 -is groundedJOne terminal of the operating windingof line relay 4 I 4 is connected to grounded battery 4|1 and the other end is connected' to conductor 4 I8 which is connected to one of the-righthand springs of each of the operatorshub circuitswitching keys 342, 343, 344, 346, 341 and 348. The other of the right-hand springs of the keys 342 to 348 are connected to the upper conductors ofthe hub circuits 30.3 to 309.

One of the terminals of jack 4|| which serves The spacing contact Aofi-,rarismitting relay 4|9 is.

connected to ground and the armature of the relay is connected to operators communication conductor4| 8. The other terminal lof jack 4|| is Aconnected to ground. f v In order to transmit the signal for starting the tape transmitter |0I at station I I, the oper.- ator inserts plug 4|3 into jack 4|' I and closes key `342. Batteries4|1 and 426 of the same polarity v and .magnitude as batteryj|33 at repeater I4 v (Fig. v1) and a correspondingbattery at repeater 20 lthus become connected to the upper conductor ofthe hub circuit 303 and no current -flows to l,energize the operating windings of any of the relays connected to the hub circuit. The opera- -tor then operates keyboard transmitter 401 to send the permutation code ysignals ywhich vwill causethe selectable member |48'at station II to be selected and operated. This selectable member maybe responsive to a signal frequently assigned to functional operations, suchl as the upper case H signal which involves the transmission of the upper case or figures shift signal followed by the transmission of the code 'signal representing the letter H. Spacing signals generated'by the keyboard transmitter 401 cause'the armature oftransmitting relay 4|9 to move' t'o the spacing position whereby ground is connected to conductor 4|8 and thus to the upper conductor ofthe hub circuit 303. Due to the removal of the battery connection vafforded byA the potentiometer consisting of the resistors 423 and `424 andthe substitution of ground to the hub circuit current Vilows through the operating windinfgr of repeater relay |32 from batteryY |33 and through the operi# ating winding of a corresponding relay from a corresponding battery in repeater 20 and through the operating winding of operator's receiving relay 4|4. Thus the armature of relayi|32 is operated to repeat the signals into the loop circuit to the station' I I consisting of the conductors I I8 and |28. It will be understood that the signals which control the selectionof selectable member |48 at the station II and to which the selector magnet |64 at station I6 also responds should not perform any switching operations in the switching selector mechanism located at station I6.

vUpon. the closure of the contacts |46 controlled by selectablemember |48 at station I I, relay |5I is operated as previously described to eiect the energization of start magnet ||3 and the release of distributor shaft |01 for rotation to transmit signals over the loop circuit of station II. No further attention of the operator controlling the apparatus in Fig. 4 yto the transmission of the message from station II to station I6 is required and, accordingly, the operator may open key 342 'to-.disconnect the operators set from the hub circuit 303.

.In response to the signals generated by the tape transmitter IUI, the armature of repeater relay I3I at repeater I4 is oscillated between its marking and spacing contacts. When the armature is on the marking contact, continuity of the circuit from battery |33 through the operating winding of relay |32, through the hub circuit and through a relay corresponding to the relay |32 to battery at repeater 20 is preserved so that the receiving relay at the repeater 20 does not operate. When the armature of relay I3 I moves to the spacing contact ground is connected over the hub circuit to the receiving relay at the repeater 20 so that thatrelay operates to its spacing position to repeat the spacing condition to the loop circuit comprising the co-nductors |62 and |63. The armature of relay I3I in leaving the marking contact opens the circuit of theoperating winding of repeater relay |32 so that the armature of that relay does not move to its spacing condition and thus does not reect the signals generated by the `tape transmitter I| back into the loop circuit comprising the conductors I I8 and |28.

The rst signals in the tape are those which will cause either or both of the selectable mem- `bers I 1I and |12 to be selected, and if both are to be operated, they will be selected successively in response to successive signals. `In response to those signals, either the receiving-only printer |69 at station I6 or the receiving-only printer I6| at station or both of these printers will be connected to the loop circuit comprising the conductors |62 and |63 to respond to the message signals generated by the tape transmitter |0| at station I I.

In the tape which contains the message to be transmitted by tape transmitter IUI, there should have been perforated by the attendant a signal at the end of the message to which the line relay I9 and -printer |03 will respond to select the select- .able member |49. This signal is preferably the blank orall-'spacing signal in order to provide a continuous spacing condition on the communication channel lof suiiicient duration to cause electro-n discharge tube 222 to respond. In response to the nal signal the selectable member I 49 operates. contacts |41 to complete the energizing circuit'for the' relay |54. This relay operates to open the holding circuit for the relay I5I which releases the energizing circuit for the start magnet ||3 which, in tum, releases its armature and tape transmitter |0| is stopped. The release of armature' |58 of relay I5!` removes the short circuit across the transmitting contacts of keyboard transmitter |02, restoring that transmitter to operative condition. Theblank signal may, if desired, be employed for selecting the selectable member |13 at station I6 to open the contacts |11 and release the holding circuit for either or both of the relays |61 and |68 to disconnect the receiv, ing-only printers I6I and |69 from the loop circuitcomprising the line conductors |62 and |63, thus restoring station I6 to normal condition.

In response to the blank or all-spacing signal, the relay 208 in the control circuit 2|, which is at all times responsive to signals on the communication channel, holds its grounded armature on its front contact a suilicient length of time to cause condenser 2|3 to charge vand raise the potential of the grid of electron discharge tube 222 so that the tube becomes conductive and plate current iiows through relay 221 to energize the relay. A circuit is completed from the grounded front contact of relay 221 through the armature of that relay, right-hand armature and back `Contact, of relay 228, conductor 229, inner left-hand armature and front contact of relay 23|, conductor 246, conductor 241, disconnect indicator lamp 35|, conductor 352, Winding of relay 244conductor 224 to grounded battery 226. Thus the disconnect lamp becomes operated in series with relay 244. A holding circuit for relay 244 through the disconnect indicator lamp is completed from ground through the inner right-hand armature and back contact of relay 228, conductor 233, conductor 234, right-hand armature and front contact of relay 23|,.conductor 248, left-hand armature and front contact of.relay 244, conductor 246, conductor 241, lamp 35|, conductor 352, winding of relay 244, conductor 224, to grounded batteryl 226,whereby lamp 35| is maintained illuminated uninterruptedly. After'the transmission of the blank signal Which caused the disconnect indicator lamp 35| to be operated, the tape transmitter I 0| comes to rest with the brushes engaging the stop segment so that a steady marking condition is established in the communication circuit and relay 208 is restored to the deenergized condition. Upon the engagement of the back contact of relay 208 by its armature, the condenser 2|3 is discharged and the conductivity of the electron discharge tube 222 interrupted so that relay 221 is released. Thus the relay 244 is held energized solely by the previously identied holding circuit.

The right-hand armature of relay 244 which is connected to ground, completes a circuit through the right-hand front Contact of the relay and through conductor 231 and key 40| at the operators position to the audible alarm 402 whereby the alarm is operated. This attracts the attention of the operator who observes that lamp 35| is operated to indicate that the message transmission from station I I to station I6 has been completed. .In compliance with this indication the operator restores keys 3II and 33| to normal position. Upon the opening of key 3| I, conductor 321 is disconnected from' the hub circuit and conductor 328 is disconnected from conductor 320 at the left-hand springs ofkey 3| I. The energizing circuit for the relays 202`and 23| in series includes the conductors 328 and 329 a's previously described so that upon the disconnection of these conductors both of the relays are released. Relay 202 upon being restored to nor; mal condition removes the left-hand or marking ycontact of repeater relay I3| from the circuit of the operating winding `oirelay |32 and restores ycloses keys 3|| and 342 and inserts plug 244 at' the right-hand' armature of relay 23| so that relay 244 is released, thus disabling the operation of the disconnect'indicator lamp 35| n'd removing ground from the ycircuit of the audible alarm device 402. The opening of key 33| releases the relays in the control circuit 25 corresponding to the relays 202 and 23| of the control circuit 2|, thus restoring the control circuit 25 and the'repeater 2 0 to normalor idle condition.

It Will now be assumedl that the attendant at l station n' operates can initiating key'lae to' in vdicate a message to be transmitted to one ofthe Vstations I2,` I3and I5. yThis calls intooperation the vibratory 'system consisting of the relays |24,

ing of the conductors |I8 and; |28' which results inthe operation of relays 208, 221 and2 I8 in 'succession inthat order. The relay 2I8 establishes its holding circuit'as in the previously described operation, and as soon as the attendant'at station I I releases key |36 and permits it to remain open, the vibratory relay Asystem operates to cause relay |21'to'open`an`d. close alternately the loop cirlcuit. The relay 2 08 follows the alternating conditions of the line and cyclically provides an energizingv circuit for the relay 2|8 inshunt with message through the mediumof telegraph sisnals to be transmitted fromstation Assum- .ing that hub circuit 303Y is idle, the operator 4|: inte jack 409 and plug 4|'3`into jack 4|I. Key 3|| operates as previously described to extend the communication circuit from station I I to the hub circuit 303;'and to energize relays 202 and'23l, the latter of which releases theholding rcircuit for the relay `2|8 whereby the iiashing callv destination indicator lamp 30| is disabled. The operation of the key 342 connects the operators position apparatus to the hub circuit 303.` These operations do not disable the vibratory! relay mchanismat the station II and it.is Anecessary for the operator toeffect the disablement of that mechanism. This is accomplished by opening the operators break key 408 to 'place ,thecomniunication circuitextending from the operators position to the repeater` I4 in spacing condition.

.Theopening of break key 408 causes the armatureof repeater relay |32`to move toits spacing positionv thus disconnecting marking battery |33 from the operating winding of repeater relay ;I3 I and from the loop circuit comprising lthe'conductors I8 and |28. The loop circuit `must be maintained in spacing condition bythe relay |32 f long enough to assure thatjthe operationof `the vibratory. system has reached a portion'of its cycle in which relay I'2'| is deenergized and the loop circuit contacts controlled by its armature |26 are closed. When the vibratorysystem is in thatcondition the operating winding ofA relay |24 is deenergized With the'rnarking battery I 33v disconnected fromithe loop circuit. the circuit` through the holding Winding of relay |24 is interrupted s'c that the relay '|24 releases its destination indicator lamp operating oscillations of theline, and interrupts the circuit through the armatureand back contact of relay |42 for energizing relay "|31, Thus the relay |31 cannot become reenergized and the vibratory circuit system is disabled. After holding break key 408 open i'or a suflicient length of time to cause the vibratory relay circuit tobe disabled the operator transmits signals by means of keyboard transmitter'401 to instruct the attendant at station I to proceed with the transmission of the destination of the message to be transmitted from station II.l The attendant'a't station I -I thereupon operates keyboardtransj. mitter |02andtransmits signals conveying the identityiof 1th`e station that is being called. The station identification information is recorded by the -operators4 receiving' printer 406. yAssuming thatr` the message destination information rec'ei'ved from station |I indicated tothe operator that connection with station/I5 isdesired, vthe operator closes the uppermost key in the bank 'of keys 32|, this key being identified` 'by the reference numeral 350,to connect the communication conductor 353 of control rcircuit 24 to the hub 'circuit 303 and tc operate relays in the control circuit 24 correspondingto therelays 202 and 23| in the control circuit 2 I'. The control circuit 24 conditions'th'e repeater I9 for message transmission between station I5 and the'hub circuitl 303 in accordance with half vduplex principles anvd'alsc prepares'an energizing circuit for the disconnect relay in 4control circuit24 correspond-` ingfto the disconnect relay 244 in control circuit 2 l Following the'clos'ure of key 350 the operator operates keyboard transmitter 401 to instruct the attendant at station I to proceed with the transmission of the message. f If themessage transmission `:fromstation is `tov be accomplished by direct lkeyboard trans-.- mission the attendant proceeds to operate keyboard transmitter. |02. If vthe message intended for station I5 has been .perforated in ,a tape and the tape has been placed in tape` transmitter IOI thejattendant atstation ||4may initiate-the tape transmission byoperating start' key |53 which causes relay `I5I to become energized and held over the previously yidentiiied locking circuit which it establishes. It will be understood that the'inessage is not recorded at station I5 on the receiving-only printer' I 6I kbut is recorded by a printer corresponding to the receiving printer |03 atstationlL `At the conclusion of intercommunication be.- tween I4stations .|I and I5 thendisconnect signal maybe given from either station. In the event that the message is transmitted by tape transmit.- ter |0| from station |I and there is no occasionv r for' station' I5 to reply while the connection :beffvtween the two stationsis maintained, the blank 'signal combinationmm'ay be'included in the tape ,atthe end of the message to cause the operation of'selectable member |49 Vwhereby contacts |41 l .graph stations.

ing zrelaydn lcontrol :circuit 24 dao operate 1a morresponding electron =.discharge tube .in that control circuit. .In :the ,control circuit 21 relays 221 and 24.4 will heioperatedfin :succession to causeidsconnect damp .-35.4 tofbe oneraied. .In the control circuit '24, relaysfcorresponding to the. relays 221 and 244 `will be operated to :causefdisconnect .indioatorlamp '.354 associated with the .tank :of .keys 32| to be .-operated.. Thereupon the operatorfat the central o-fice switching stationwill' restore keys 131| I and .350 to lnormal "whereupon the relays .cast to eff ect the'energization .in `.the control circuits 4ci the :selected :stations ofv the relays corresponding .to-fthe 4relay :235| in lthe control cir- .cuit "2| without effecting .the energization ci l.the cut-.through relay v202 since .the latter :relay may remain .in .the .normal or deenergized con dition for. .transmission Ato the telegraph :station associatedv therewith.

inthe control `circuits and '24'wi11he restored to normal.

:In vaccordance with ione contemplated `adaptation .of the system according to the present .in lMention, traffic conditions :are .such that there is little or .no..occas1on ,ior communication 'between stations |.5 .and I6 -due to the -fact that the :stations :|25 and .I6 mayv be located in .dinerentdepartments of .a renewal .oflce .in 2a single. Seo,- sraphieallooation. .It is `also contemplate dthat one .of .the othertelegrama'` stations, such .as the station -|..3, may be .located` at Y a general head- -quarters cnice-of .theisystem inra diierentneo graphical `location iromthestations LS1-and .It andalso trom the stations -|f| and,|.2 and ywher-.eas .a `large percentage `of .theftrafiic stations .|.I .and .|.-2 -and-alsoof .the traffic initiated bythe station 13 may =be intended for'the station L6.. :a largepercentage of the .trailic ,initiated by the station |-5 may .be intended .for .the general headquarters oiilce |3. With rvtraillc.conditions ,existing .as .outlined above, the. operator at fthe-.central .oflice :switching station may .he instructed thatcalls originating :at the stations |.2 and 13 .and indicated by .steady illumination 4of :the call kvdestination. indicator lamps 30|., .323 .and 324 indicatemessages to .be ,transmitted .to thestation .`|i6 .which may be completed. .by .direct.s.w.itching operations withoutanswering to inquire as .to .the destination of .the message gto .be transmitted. Similarly, the operator may lbe .instructed that calls initiated 1by .the .station |.5 represented `by steady illumination .of call .destination indicator lamp .may be .switched .directly 'to the general headquarters office station I3 without inquiry by the operator as .to thedestination. .It will follow from .this that calls .initiated .from any of .the stations 1 I2, |'3 and v|.5 evidenced by ilashing of their call destination .indicator .lamps 30|, .323., :324 .and 326 are to be answered by the operator and inquiry. made .as vto .the .destination of ,the call, the injury to be followed lay operation of .the proper station connecting'keys after .the .call destinationv information has beenv received.. It` is v.toloeunderstood that this operating. routine is predicated upon the particular trafc conditions outlined and upon particular .relationships of the .stations from anxorganizational standpoint and that different 'tramo conditions ordiiereni organizational relationsmay render. desirable .the practice of different operating routines in re vsponse to steady or flashing operationof .the sev' eral'call .destination indicator lamps.

As is yfully disclosed in 4.the .hereinheforeiden- 'titled patent oi iF'. S. Kinkead etal. theiopera "tors' position apparatus. includes. key-s 432| .and .432 for setting` up broadcast conditions. upon .selective or .group basis .to .enablethe 'operator to -broadcast .to .certain ones .or all .of the tele Thekey 143|. provides for selec.- tive station broadcast .and utilizes the second or `louter conductor or one or more .ofthe hubcircuits in cooperation. with' aline key of .each .of the stations to which the .messageis to behroad Upon .the -closure .of key 43| ground .is con.- nected throughthe .key and throughconductor 433 to the left-handspring of .each of the keys 342 .to 348..by which `the yoperators .position apparatus .may fbe connected to ythe huh circuit. Assuming thaty the .operator closes key 342, the .ground ffrom selective -broadcastkey 43| will be connected -tothe `lower of the hub circuit condoctors .303. Assuming `also that telegraph station -is one of those to which` the operator wishes to broadcast, the.` key 3H `will. he closed and. whereas .in lthe `preyious description of interoommunication .between station and one .of the'cther stations, the, conductors 328 .and 329 were merely .connected together .at 4the .key 3| l., both of thoseconductors will .be groundedat .the key ..3.|.|. .due .to the .fact that `the .lower of the conductors of huhcircuit .3.03 is grounded. .Conductor .32Bextends .through the winding 0f cutthroughrelay .2.02 .and through theback contact and inner right-'hand armatureV o'f` Irelay 228 .to ground .so that the .relay2ll2 willnot beenergized. Conductor .3219 extends .through theloack contact and inner'left-Jhand armature .of ,relay `228 and the circuit continues through resistor .242, conductor. 243, winding of relay 23| and conductor 224. togrounded battery .226 `Wlfxerehy 'the relay 235|. will 'be energized independently of the re- 1ay'22.

The communication circuit is completed from the operators position over the upper conductor of' the huhcircuit '303 and through communication .conductor 32.1, back .contact and outer lefthand .armature of relay 22.8, .conductor'24'l righthand armature and back .contact of relay 282 to conductor 2|l| which extends 'to `repeatery |4. Thus the operator may transmit to station v|-| but station I may not transmit to the hub circuit 3.03 because .the circuit ofthe transmitting armature cit-relay |3I .is opened at the liront contacts of relay 1,202. vIl? the station interferes with the reception ofthe broadcast material by opening the loop circuit either by means of the break key |2| or by one .of the call initiating keys |22 or |36, the relay 20.8 of the control circuit will respond and will .operate lthe timing circuit of electron discharge tu'be 222 .to effect the opera- 'tio-n. of relay 221.` This will not cause the call indicator'larnp of .station `Il to be operated but mission which would justify .the operator. in in- .terrupting the broadcast transmissionand delaying it until station has had an opportunity .to transmit the urgent message.

At` theconclusion .of the lselective lloroadcast `transmission the .operator opens. key 431 key '.342 .andkey 3U andany otherssuch as the keys 3U to 3H or any offthe keys in thekeybanks operated.` Similarly,- the relay correspondingtol 4 the relay 23| `in-all `of the control circuitswhich had participated in the broadcast transmissil n. willbe released. ff

- '.*Group Hbroadcasting contemplates that per-` marient connections shalll exist between .certain or allgof the controlA circuits shown in Fig.` 2 and apparatus at the operators position sothatr direct.

transmissionirom theoperatons positionto certain or all ofthetelegraph stations may.;be ac-v complished Without operating theline keys'in the switching apparatus. Group broadcasting isfinitiated `byclosure ofv key 432 which grounds one Yterminal, of the ywinding .of relay 434, the other terminal of which is connected to grounded the middlearmature engages its grounded 'front contactto complete the circuit from. groudbyer l conductor- 436', Winding vof relayr 228, ycoirlductiir.v

249, back contact 4and outerv lefthand armature of relay`23| if broadcasting is on ay nonseizure "basis, otherwise `through a conductor represented bythe dotted line'shunting'the back contact and outer left-hand'. amature of relay '23| y'when broadcastingison 'a seizure basis, and conductor.

224, tofg'rounded battery 226,,Qf1he uppermost armature and vfront ycontactofrrelay 434 com'- pletes a' signal. transmission 'path from'fthe. transmitting'annature off the. operatorstrans"-` niitting relay f4|9 over conductor 4|8,1conductor' f 431,A rfront contactand uppermost 'armature'yof relay 434, conductor 438; front contact and outer left-handarrnature of lrelay l228 which vrisfnow energizedgconductor 24|, 'right-hand armature rldb'ack contact of relay 2|)2v 'to iconductor-20| which extends to repeater |14. Thus a-trans mission path is extended from the op'erators position directly tothe station I I without operating any of the keys 3| I Vto 3H.' It is to be noted in Fig. 2 that branch conductors extend fromthe conductors'` 43B 'andf438 to other control circuits for-.operating the broadcast relays in those circuits and for'extending the ldirect transmission path 'rom the operators set. l i

t "The 'relay 2 28, Iupon being energized, .accome plislhes'cerltainv results other than the transfer-:of the v'communication channel extending'ito a telegraph station, such as the station ||,v from the line keysidirectly tothe operators set;r Theinner left-hand armature opens at its. backcontacty the.

energizing circuit for the rrelay 23|,.so-that i'lhat relay cannot become energized even if: a line key for a y'station includedY in the-group broadcast should be closed. The inner` right-hand armature of relay 228 prepares a holding. circuit for disconnect relay 244 from the grounded armature and'front contactgof relay 228 over conductor 25|A to the .left-handvarmature ofrelay 244. This provision is madefor preparation of a vholding 1 f circuit. for relay 244'because relay 23| which n'or-` mally prepares a holding circuit for relay .2443s at this time deenergized. At the middleirighthand yarmature and front contact of 'relay 228..'an

energizing circuit is prepared for the. disconnect relay.244 directly to the conductor241 andV not through therconductor 229 rand innery left-'hand armature ofrelay 23| since that relay is" atthis time deenergized. Thef extreme right-hall@.armature of relay 228. interrupts a conductive path' f whichexte'nds from its back contact throug'h'the" :ill

conductor '229, inner left-hand armature and back` contact of relay ,23| Which is now deenergized and conductorv 232, which path extends through the call destination indicator lam'p 30| and winding of call *initiating relay 2| 3 to grounded battery 226. Thus, the broadcast relay 228 prepares conditionsfor the operation and holding of 'relay v244 similar to the 'preparations made by'relay V23| in connection with selective broadcast so that if a telegraph station to which.

broadcast signals are being transmittedinter-v feres with the reception ofthe signals such interference will be evidenced by operation of the disconnect indicator lamp pertaining to that station. andy notby kthe call destination indicator lamp.'

Assuming that not all of the telegraph stations are=arranged for group broadcast reception, there maybe rcircumstances under'which it is desirable to add a particular station or stations for receptionof broadcast messages along with a group; Provision is made for this by the grounded inner.- most `armatureof relay 434, the front contact of which is connected toxvconductor l433. The'v groundedy armature -thus extends ground connection to the left-hand springs of all of the keys 342l tov348 and by the closure of one or more of thesekeys hub circuits may be conditioned'ir broadcasttransmission in the same manner as is contemplated bythe kselective broadcast key. 43|.

Any lstations vnot included in the group broadcast arrangement may -be.'added selectively to receive the v`group broadcast transmission by operating theirrline keys` to connect them to the hub circuit r orcircuits which have been prepared by opera-.:

tion-oioneor more yof the keys 342 1:0348. The; ground afforded by the innerarmature of relay 434..;wi11then complete a circuit over conductors rcorresponding Ato the conductor 329 to energize inthe control circuits of the stations that are to -b'ecadded to .the broadcast transmission, relays correspondingto the relay 23| to I#prepare 'the'.

energizingand holding circuits for the disconneet.. relays inthose controlr circuits and to. in-

terru'pt,V the energizing circuitsV for the call initi- Y atingirelays in those control circuits. As in the case. of pure selective.broadcastservice, any in-lv terference with the reception. of `broadcast ma-.

,I hated by opening key 43|, which'will release the relayscorresponding tothe relay 228 in the contr'ol.y circuits that' are vassociatedlwith the group broadcast'. and by vopening .those ofthe keysv 342` tofli348xandthe line keys that were operated to addl'fselectively `certain stations to the broadcast n service. The opening of those switching keys will release the relays corresponding' to the relay 23|',

l1 Although. a particular embodiment of the in ventionhas been shown in-thev drawings'and de? scribed in the foregoing speciiication, it is to'be i'inderstood/that the inventiony is' notlimited to sluch'speciflc embodiment but is capable of modiiicationr and rearrangement without departing scope of the appended claims.`

"What is claimed'is: v f

from the spiritof the invention andwithm the f hln a telegraph system,A a plurality of stationsk of one,v class, at least one station of another class,

.mechanism for interconnecting any two of said stations, a call 'indicator at'said switching mechanism associated with the communication channel of each of the stations of said one class, and means atv each of the stations of said one class for actuating its indicator according to one charlalcteri'stic to indicate the message destined for another station of the same class and :for actuating its indicator `according to another characteristi'c to indicate a .message destined for a station of saidother class.

2. In a telegraph system, 'a plurality of stations cfone class, at least one `station of another class, a switching mechanism, a communication channel extending from each of said stations to said switching mechanism, means in said switching mechanism for interconnecting any two of said stationaa call destination indicator 'lamp at said switching :mechanism associated with the communication channel of each of the stations of said one class, and. means'at each of the stations otsaid one class for causing its call destination indicator :lamp to be operated uninterruptedly to 1indicate a message destined for a station of one of the classes and .for causing its indicator lamp to` lbe operated intermittently to indicate a message: destined for a station of the other of the classes.

. 3. In a telegraph system, a plurality of stations of one class, atleast one station of another class, a switching mechanism, a communication channel extending from each of said stations to said switching mechanism, means in ksaid switching mechanism for interconnecting any twoof said stations, 'a call destination indicator'at said switching mechanism associated with the communication channel of each of the stations of said one class, -means local to thek switching mechanism for rendering each call destination indicator responsive to the condition of its associated communication channel, means at each o1 the 'stations ofy said one class for initiating the operation of the call destination indicator asso-- stations of said-one class for initiating the operation of the call destination indicator associated with its communication channel and for establishing 'avariable condition of said channel.

' 4. Ina telegraph system, a plurality of stations of one class, at least one station of another class, arswitching mechanism, a communication channel extending from each of said stations to said switching mechanism, means in said switching mechanism for interconnecting `any two of said stations, a `call destination indicatorV at said switching mechanism associated with the communication channel of each of the stations o-f said one class, means local to said switching mechanism for causing each of said call destinatiGnfin'diGatOrs to operatey in accordance withthe condition of the communication channel-.associated therewith, means at each of thestations of said one class for .momentarily changing the condition -of the communication channel associated therewith and for restoring said channel to normal condition for causing its call destination indicator to be set in operation and to operate steadily, and alternatively operable means at .each of the stations of said one class for causing. continuous alternation of the condition of the communication channel associated therewith 'to ,cause .intermittent operation of its call destination` indicator. i

f 5., In a'telegraph system, a' plurality of stal tions of one class, at least one station o'f another class, a switching mechanism, a communication channel normally in marking condition extending from eachI of .said stations to said switching mechanism, means in said switching mechanism for interconnecting any two of said stations, a call destination indicator at said switching mechanism associated with the communication channel of each of the stations of said one class, means local to the switching mechanism for setting in operation each of said call destination indicators, and for rendering it operable inaccordance with the condition of its associated communication channel, means at each of the stations of said one class for momentarily changing its associated communication channel to spacing condition, and for restoring the communication channel tol marking condition to cause its call destination indicator to be set in operation and to operate steadily, and alternatively operablemeans at each of the stations of said one class for steadily alternating its associated communication channel between marking and spacing conditions to cause its associated call destination indicator to be set in operation and to operate intermittently.

, 6. In a telegraph system, a plurality of stations of one class, at least one station of another class, a switching mechanism, a communication channel extending vfrom Yeach of said stations to said switching mechanism, means in said switching mechanism forinterconnecting any two of said stations, a call destination indicator at said switching mechanism associated with the communication channel of each ofthe stations of said ,one class, means local to said switching mechanism for conditioning each of said call destination indicators to be operated and for rendering said indicators operable according to the conditions of their communicationfchannels, means at each of the stations of said one class for opens-ting.l said indicator. Vconditioning means and for establishing a steady condition of its associatedy communication channel, alternatively operable means at each of the stations` of said one class for operating said indicator condition ing means and for establishing a iiuctuating condition of its communication channel, and means associated with said switching mechanism for terminating the operation of said indicators and for disabling said line condition fluctuating means. i

7. In a telegraph system, a central office station -including switching apparatus, a plurality of remote stations, a communication channel connecting each of said stations to said switching apparatus, storage type telegraph signal transmitters at said remote stations, indicator means local to the switching apparatusand associated with said communication channels, 'means fat said stations for operating the indicators lassociated with their respective lines according to one characteristic to indicate a destination of a messageto'b transmitted from Saidfstation and for operating said indicator according to another characteristic for indicating anotherdestination of a message t be transmitted lfrom,saidstation, and means in oflsaid stations, rn'eansffor storingsignals to be transmitted b y said transmittera'a communication channel connecting'ieachof said stations to saidswitching apparatus, indicator means local to the switchingapparatus? andr associated with said-communication' channels, .means at said re-Y mote stations for perating'the indicators associated with: their respective vlines according. to

one characteristict'o indicate'v a. destination of a message to be transmittedrfrom their transmitters and vfor f operating .-fsaid indicators according to another characteristic for indicating another destination .ofl at message' toi be transmitted -from k code 'mannerv repetitiously.' independently of said their transmitters, meansf'at each of fsaid stations controlledbyl said switchingr apparatus for starting its transmitter, 'and means associated with each transmitter-and `controlled therebyfor `stopping the transmitterat'the end offtransmission of the signals'containedlin said signal storing means. c f 9. In a telegraph system, a 'centraloice stav tion including switching apparatus, a plurality of remote stations, a Astored signal transmitter at each ofy said remote stations, aA communication channel-connectingfeach of said remote sta' tions to said` switching apparatus, call destination indicator. means localgto the switching apparatus and associated with saidflcommunicationv channel, means at saidremote stations fory operating the indicators associated' with theirv respective` communicationfchannels according. to one` characteristic to indicate a destination vof a mes'` sage to be transmitted vfrom their transmitters and for .operating saidindicators according. to another characteristic for indicating another destination of a message to be transmitted from\ their transmitters, a disconnect indicator `for each of said communication channels in said'switch ing apparatus, means at each of said remote sta4 tions controlled by said .switching apparatus `for starting the stored signal transmittenj means'k controlled .by saidtransmitter yfor stopping said transmitter at they conclusion of= transmissionl ofV code transmitting device, and means at said second station for transmitting over said channels and repeater to' said `first station a signaling conditionito terminate operation of said. automatil cally operable channel opening and closing` means. t

13. In a telegraph system, a telegraph'station including a code'transmitting device and a receiving device, a communication channel* connected vto said station, means at said stationfor automatically impressing signaling conditionson said channel independently of said code ltransmitting device, and means controlled by said lastmentioned means for rendering said receiving device unresponsive to said'signaling conditions.

...14.` In atelegraph system, a telegraph station including a. code transmitting device anda receiving device, a communicationchannel connected to said station, means at said station forautomatically impressing signaling conditions on said channel independently of said code transmitting device, and means controlled bysaid last- `mentioned means and effective continuously durr in'g `the operation-thereof forv disabling said rel ceiving device. i

`15. In a telegraphsystem, a telegraph station including a code transmitting device and a re-,y

ceiving device, a normally closed communication @channel connected .to said station, a pair of restored signals,y andmeans'` controlled by the trans- *Y mitter 1 for operating 'saidxdisconnect indicatorl x10.' In a telegraph@ system, va plurality of 'fstav tions of vone'.j class, a station of another class, av

switchingl mechanism, yan operators answering.

apparatus associated with said switching. mechanism,:a communicationv Achannel extending from:

each vof said stations to said switchinglmechanism, means in said switching mechanisml for interconnecting any two of'said communication channels'V a call destination indicator at saidv switchingr mechanism* associated with -the communication channel .offeach lof the stations of said one class, and means at each of the stations of said one class for. actuating its indicator accordingv t0 one characteristicto'direct operation Aof said switching Afmeclfi'anism'Ito interconnectl a station of said one' class with-*thestation ofthe other class and for vactuating its rindicator according to another characteristic to direct operation of said switching mechanism to connect said operators answeringy apparatus to a station fof said one class fory receiving call destination in-' formation. f l' 11.111 a telegraph system, laiirst telegraph* station including a codetransmittingdevice, ai'

second telegraph station, a communication chan'- nel interconnecting said stations; means at said iirst stationfor automatically impressing ultracode signaling conditions continuing vthroughout an interval f'lli-ndeterminate duration on said channel independently of said codetransmitting lays eachhaving means for closing and opening the..y energizing *circuit` for the other, manuallyf operable vmeansfor closing the energizing circuit of -one of said relays, and means controlled by said `onerelay when it is energized for opening said communication channel to establish an offnormal signaling condition independently of said 'code 'transmitting device.

16.In a telegraph system, a telegraph static'mv including a code transmitting device and a Yreceiving device, a normally closed communication vchannel connected to said station, a first relay,-

y"manually operable .means` for completing the` energizing circuit ofA said relay,l a second relay energizable under the vcontrol ofy saidr first relay, means controlled by said second relay for completing the energizing :circuit of said rst relay,v

omeans controlled by said rstrela'yjfor opening saidnormally closed communication channel, and meansresponsive to opening of said channel independently of' said last-mentioned vmeans for i depriving saidisecond relay of control overl the energizing circuit of said first relay;

17. In a telegraph system, a telegraph stationl including a code transmitting device and a receiving' device, a central oiiice switching station, a*

normally closed communication channel interconnecting said stations, means at said telegraphv station for automatically opening andclosing said channell repetitiously, manually operable means at saidtelegraph station for settingin operation" y said automatic 'line openingfand closing means,

"a relay `at said centraloiiice switching station operabley in .response to opening ofjsaid communication channel, a second relay controlled by said relay having in series' with the energizing circuit thereof an indicatorlamp, meansfor completing a .holding ,circuit for said second relay. and meansv controlled by saidsecond relay for preparing a substitute energizing circuit for said secondrelay to be completed by said iirst relay i in short-circuiting relation to said indicator lamp insresponse to the repetitions opening of said communication channel.

`18. In ay telegraph. system, a iirstl statiorna second station, a communication channel interconnecting .said stations, a call indicator at said secondstation, relay means at said second .station responsive to signals `generated at said `iirst station. timing means controlled by said relay means and operable after a `predetermined 'interval of maintenance of a predetermined condition ofV said relay means, second relay means associated with said ,call indicator `and operable with said call indicator by ksaid timing means, and means operable.. b y said `second relay for `placing said call indicator vunderthe control of said. first mentioned relay means, Y

19. In a telegraph system, a rst .stationga Second station, a communication channel interconnecting Said stations, a call indicator lamp at said second station, relay means. at said second station responsive to signals generated at said nrststation, timing means controlled by said re laymeans and operable after .a :predetermined interval of off-normal condition of said .relayl pluralityof outlying stations, telegraph lines extending from said central station to saidoutlying stations, call indicators associated with said lines.

at said vcentral station, disconnect indicators associated with Vsaid lines at said central station, means for establishing communicative comicotion between said central station and aplurality of `said lines on selective basisor fixed group basis, and means controlled by said lastementioned means for rendering only said disconnect indicator operable in response to call initiating operations at -said outlying stations..

21. In a telegraph system, a central station, a

plurality of outlying stations, telegraph linesextending from said central station to said outlying stations, call indicators associated with saidlines at said central station normally responsive to .call initiating operations at said `outlying stations, disconnect indicators associated with saidlines at said central station normally responsive to disconnect signals transmitted from said outlying.

stations,l means for establishing communicative connection between said central station and a plurality of said lines on selective basis. or xed group basis, and means controlled by said 1ast-..

mentioned means for rendering only said disconnect indicators operable in response to;v call initiating operations at said outlying stations.

, tral stat-.ionto said outlying stations only, and

moans controlled by said last-'mentioned means for rendering `only said disconnect indicators on.- erable in response to call initiating operations at the'stations so connected.

.Z3-In a .telegraph exchangesystm, a central.

oilice station, a plurality of remote, stations, a communication channel extending from each of said remote stations to said central otllce station, means at said central oilice station for interconnecting any two of said channels, means asso.- ciated withv all but one of said channels atsaid central4 Oflce station for indicating a message destined for ysaid one channel `and for indicating.

a message destined for any other of said channels, and means at. all of said remotestations except the station associated with said one .channel for:

24. In a telegraph exchange system, a central, cnice station having a teletypewriter set, a plurality of remote stations each having a teletypewriter set, a `communication channel extending.

from each of said remote stations to said central oilce station, switching means at said central oice station for connecting the teletypewriter set thereat to any of said channels and for inter connecting any two of said channels, means asso ciated with all but one of said channels at said lcentral oice station for indicating a message A destined for said one `channel and for indicating a message destined for any other oisaid channels or said teletypewriter set at said central oilice. station, and-means at al1 of .said remote stations except the-station associated with said one chan-A ,nel'ior selectively causing its .indicating means at said .central oice station to. produce either of said indications.

2&5..` Ina telegraph exchange system, a central Office station having `a teletyp'ewriter set, a llll rality of remote stations each `having a teletypewriter set, a vcommunication channel extending from each. of said remote stations to said central office station, manually operable switching means at. said central .olllce station for connecting the teletypewriter setthereat to any of said channels 'and for interconnecting any two of said chaml nels, moans associated' `with all but one of said channels at said central office Station. for indicating a message destined for said one channel.

and yfor indicating a message destined for any other of said channels. or: said teletypewriter set FUnLERToN s. xmlsoap. Jessen A. nascar.

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