US1280783A - Ring-back arrangement for common-battery telephone party-lines. - Google Patents

Description

F. LUBBERGER.

RINGBACK ARRANGEMENT FOR COMMON BATTERY TELEPHONE PARTY LINES.

APPLICATION FILED SEPT. 19. 1907- RENEWED FEB. 23, 1918. 1,280,783.

Patented Oct. 8, 1918.

3 HEETS-SHEET I A ffmvz 8W F. LUBBERGER.

RING BACK ARRANGEMENT FOR COMMON BATTERY TELEPHONE PARTY LINES.

APPLICATION FILE'D SEPT. 19. 1907- RENEWED FEB. 23,1918. 1,280,783.

Patented Oct. 8, 1918.

3 SHEETS-SHEET 2 *1IIIIIIlIIIHIh A KF. LUBBERGER. RTNG BACK ARRANGEMENT FOR COMMON BATTERY TELEPHONE PARTY LINES. APPLICATION FILED SEPT. 9. 1907: RENEWED FEB. 23, I9I8.

1,280,? 83. Patented 001;. 8, 1918',

3 SHEETS-SHEET 3.

\I 0; g\ Q o QQQ kl h N {353R Q M 3 ggkR 3 A v we WE s m R {BE g U I ED sra'ras PATENT 'UFFICE.

rnrrz LUIBBERGER, or oHIcAeoJLLnvoIs, ASSIGNOR, BY Muslin ASSIGNMENTS, T

AUTOMATIC ELECTRIC COMPANY, A CORPORATION or ILLINOIS.

RING-BA CK AERANGEMENT FOR COMMON-BATTERY TELEPHONE PARTY-LINES.

' Specification of Letters Patent.

Patented Oct. 8, 1918.

Application filed September 19, 1907, Serial No. 393,654. Renewed February 23, 1918. Serial No. 218,899.

. have invented a certain new and useful Improvement in Ring-BackArrangements for Common-Battery Telephone Party Lines, of

which the following is'a specification.

My invention relates to automatic partyline telephone systems in general, but more particularly to the non-lnterfering and intercommunicating party-line system dis closed in my nor. application Serial No.

. 393,653,' filed ept. 19, 1907, as will herein-.

after morefully appear.

Objects of my invention are to provide a party-line system of this character in which same line is adapted to control the {low of talking current to the subscrlbers l1ne, as

"the electrical current for. talking purposes is supplied from the exchange or central station; in which the special ring-back arrangement' for use between subscribers onthe well as to control the trunk-release circuit through the first-selector or other switch; in which the line circuit is controlled by a relay common to all of the subscribers ona party-line, which relay is energized by battery current flowing over one side ofthe' line when an subscriber presses his rin ng-key, the win 'n "or coils of said relay. ein included in 51 is common to the difierent substations, there- 'by preventing the release of the apparatus at the exchange which would otherwise take place should the called subscriber happen to] answer before the line is grounded the last time at the callin substation; and i'n'which certain details an features of improvement and novel combinations are employed for in- -To. the foregoing and'other useful ends,

my invention consists in matters hereinafter Gt fOIth and claimed. 9, v

In the accompanying drawings Figure '1 is a diagram showing an 'autornaticparty line system embodying the principles of my invention, in which central ener is used for talkin and signaling. It willbe seen that the su stations A, A and A are allot:

ted to the party-linethat terminateslat the central oifice in the first-selector switch C,

which latter may be of the general'type disclosed in United States Patent No. 815,321,

e connection to ground w ich general efiiciency and service-l subscrlber after havlng properl granted March 13, 1906, to Keith, Erickson and Erickson, having rotary and non-rotary movements. At 1) is shown an arrangement by means of which any subscriber of the party-line may ring back upon his own line.

A central battery for talking and operating purposes is shown at B having its positive terminal referably grounded at Gr, and a central ringer generator for signaling is shown at E.

ferent lines. -The substation .A is similar to substationsA, A and A and, as shown, is'allotted to the first-selectorswitch H.

. It will be understood that in the central 'oifice, in addition to the first-selector; switches allotted to the subscribers, lines, 'there may be second-selector switches of the same general type, and connectors of the general type shown in United States Patent No. 815,1 6, granted March 13, 1906, to

Keith, Erickson andiErickson, by means of which the subscribers may establish connecthis purpose the various bank levels of the switches may be and are provided with trunk-lines leading" to second -selector ,tion with lines other than their own. For

switches, and likewise from thesecond-selecj tor'bank levels with trunk-lines leading to the connector switches, as is customary. With my new system one level, either in the the trunk-lines from the contacts in some certain level, instead of leading to a' selector or connector switch, lead to a ring-back arrangement, as shown at D in Fig. 1; and a operated the central office switch or switc es and es tablished connection with said ring-back 'level, may then cause ringing current to pass back over his line to signal-some other I subscriber occupying the same line with him. j In Fig. 1 this ring-back arrangement is shown allotted to the second level of the first-selector banks. either of the first or second selector banks,

Any level, however,

may be e uipped in the same manner.

first or second selector bank,'is allotted to the signaling device, as shown at D-that is,

, The su stations may be of any suitable or approved type. The ones in connection with which I have elected to illustrate my invention comprise the receiver 2, a switch- 1100113, which is provided with cam-arms switch-hook is down the cam-arm 6 carries the spring 14 out of engagement with the spring 15, by which the substation ground G is cut oil. When the switch-hook is up, however, the 'cam-arm 7 presses the springs l6 and 17 into contact, whereby the transthe side switch is in normal or first posimitter 18 in series" with the primary winding 19 of the induction-coil 20 is bridged across the main line conductors. The secondary winding 21 is included in a series circuit with the'receiver 2. The calling device, as shown, comprises two push-buttons 22 and 23 which, when pressed, are adapted to carry the springs'24 and 25 out of engagement with the contact points 26 and 27 and into engagement with the ground post 28. The signaling deviceby means of which the subscriber may ground the vertical line conductor to signal a called subscriber comprises a push-button 29 which, when pressed, carries the spring 30 out of engagement with the spring 31 and into engagement with the contact point 32. Allotted to the main line conductors 33 and 34, which are common to the substations A, A A etc., there is a relay 35 composed of two windings 36 and 37. The winding 36 may be of comparatively high resistance, while the winding 37 is comparatively low. This relay, upon energizing, operates to disengage the springs 38 and 39 and to carry the springs 40 and 41 into contact. When the springs 38 and 39 disengage, then the rotary line conductor 34 is disconnected from the substation. The'engagement of the springs 40 and 41 provides a shunt or short-circuit for the winding 36.

The first-selector switch shown at. C is constructed as follows The switch shaft (not shown) carries the vertical and rotary wipers 45 and 46, respectively, and the private wiper 47. The side switch is well known and comprises the side switch wipers '48, 49, and 51, which may be designated as the vertical, rotary and private side switch wipers, and the rotary magnet wiper, respectively. The side switch is under the con'trolof the private magnet 52, and when tion the wipers 48, 49, 50 and 51 occupy the contact points 53, 54, 55 and 56, respectively. In the second position the wipers rest on the contact points 57, 58, 59 and 60, respectively, and in the third position the contact points 61, 62, 63 and 64 are engaged by their tion, is energized. .The vertical and rotary line relays 65 an'd67, acting conjointly, pro- Videmeans whereby the subscriber controls the release magnet 69 while the side switch is in the first or second position. If the sideswitch 1 passes to the third position, --then, since the selector is of the trunk-release type, the selector is controlled by means of the back-release relay 70 from the next switch with which a connection is at that time established, through the private wiper I 47. The bridge-cut-off relay '71 is provided to open the connection between the line relays 65 and 67, and between said relays and battery B. This is desirable, because if the relays are not disconnected from each other and battery the ringing current for signaling the subscriber may 0 erate either or both of the relays'65 and 6, and cause some I interference with the switch. It is also desirable to remove the bridge formed through the said relays from across the line to give the voice-currents as clear a path as possible. In addition, the firstselector is provided with a normal arm 72 which, when the shaft is raised, permits the spring 7 3 to pass out of engagement with t e spring 74 and into engagement-with the spring 75. The normal conductors '76, 77 and 78, over which'incoming calls are made, terminate inthe connector banks, as' is usually the case in systems of this general character. a

The ring-back arrangement shown at. D comprises the vertical and rotary line relays 79 and 80 connected in series with the windings 81 and 82 'of the difi'erential relay 83',- and tothe battery terminals. A dead resist-- ance coil 84 is provided in the trunk-release circuit to cut down the flow of current through the release relay 70 of the selector, which relay is of one-half ohm resistance. The ringer relay 85, upon energizing, operates to bridgethe terminals of the ringer generator E across the line conductors. The condensers 86 and 87 are provided for bridging the impedance in the vertical and rotary line talking circuits.

The connector switch may also be of any suitable or approved type, for instance of the general type described in said connector patent. The mechanical details ofthe selector and connector, as is well known, are

7 very much the same, although there is some material difference in the clrcuits. For instance, the connector switch shaft (not .shown), like the selector switch shaft, carrice the line wipers 124 and 125 and the private wiper 126. The connector switch is also controlled by the calling subscriber through the medium of the vertical and rotary line relays 127 and 128. The vertical line relay 127 directlycontrols the vertical.

magnet 129 and also the rotary magnet 130. The function of the vertical magnet 129 is to give the shaft and shaft wipers a vertical motion, and the rotary magnet 130 imparts to the shaft and shaft wipers a rotary or circular motion. The rotary line relay 128 controls the private magnet 131, whichlatter, under certain conditions, controls in turn the vertical and rotary magnets 129 and 130, the release magnet .132, and also the side switch wipers 134, 135, 136 and 137. The side switch of the connector, like the I side switch of the selector, has a normal or first osition, a second position and a third means of the vertical line relay 127, to con-' trol the ringer relay 144 by means of "which the ringer generator E is bridged across the. terminals of the called line to signal the called subscriber. The back-bridge relay 143, comprising the windings1145 and 146,

rovides the called subscriber with talking battery current when the primary circuit of the called substation is bridged across the line. The central station is equipped with the busy-signaling apparatus I of any, suitable design, as, for example, the one comprising an interrupter 147 in series with the primary winding 148 of the induction-coil 149, whereby a busy-signaling current is in-' duced in the secondary winding 150 of the said induction-coil. Thesecondary winding 150 is connected with the side switch wiper 135 through the normal springsl51 and 152 when the switch shaft is raised and the side switch is in first position.

A clearer understanding of my invention may be had by considering its action when one subscriber operates the central office switches to call back on his own line.

lit will be assumed that subscriber A desires to signal the subscriber at substation A, in which event the selector switch to the line conductors 33 and 34 o allotted arrangement D which is allotted to the second level of the first-selector banks. The subscriber at substation A removes the receiver 2 from the switch-hook 3, whereby the springs 14 and 15 engage, thus providing ground for the.ground post 28. Since the ring-back arrangement is allotted to the second level of the first-selector, the vertical line conductor 33 is given two ground impulses and the rotary line conductor 34 is given one. The push-button 22 is, therefore, pressed twice, whereby the spring 24 is carried onto the ground post 28 twice, and as a result the vertical line relay 65 of the firstselector C is energized each time by a flow of current from the subtation ground Gr through the springs 14 and 15, ground post 28, spring 24, vertlcal line conductor 33, side switch wiper 48 and contact point 53,

throu h the vertical line relay 65, bridgecut-o relay springs 88 and 89 to the battery lead 90, thence through battery B to ground G. The vertical line relay, upon energizing, operates to place the line relay springs 91 and 92 in contact, thus in turn closing an energizing circuit through the vertical magnet 66. The vertical magnet is thereby energized, and the wipers 45, 46 and 47 of the l selector 0 are raised to the second bank level and brought opposite the first contact.

The energizing circuit for the said vertical magnet 66 extends from ground Gr through the springs 91 and 92, private magnet springs 93 and 94, through the vertical ma net 66 to the battery lead 90, thence throug battery B to ground G. The rotary pushbutton 23 is thenpressed, carrying the spring 25 onto the ground post 28, thereby establishingan energizing circuit throu h the rotary line relay 67 extending from t e substation ground G to the round post 28, spring 25,'through the springs 38 and 39, rotary line conductor 34, side switch wiper 49, contact point 54, through the winding of the rotary lme why 67, bridge-cut-ofi' relay springs 95, 88 and 89 to the battery lead 90, thence through battery B to ground G.

The rotary line relay, upon energizing, presses the springs 96 and 91 into contact, thereby establishing a circuit through the private magnet 52 extending from ground G? through the springs 91 and 96, private magnet 52 to the battery lead 90, thence through battery B to ground G. The private magnet, upon energizing and deenergizing, permits the selector side switch to pass from first to second position, permitj ting the side switch wipers 50 and 51 to engage the contact points 59 and 60. The closure of connection between the side switch wiper 51 and thecontact oint 60 provides an energizing circuit for t e rotary magnet 68 extending from ground G to the side I is operated switch 51, interrupter springs 97, through to establish connection with the ring-back the winding of the rotary magnet 68 to the thence through battery Bto ground G. The

battery lead 90, thence throughbattery B to ground G. The said rotary magnet 68 .then operates to rotate the Wipers 45, 46

and 47 into engagement with the first c0ntact of the second level, from which contact, it is assumed, the trunk- line conductors 98, 99 and 100 lead to the ring-back arrangement D. If the first trunk-line is busy, however, and the wipers have to pass over busy contacts, then as soon as the private wiper 47 engages the first grounded private bank contact point the private magnet 52 again energizes, locking the side switch in second position. The energizin circuit for the said private magnet exten s from ground. G through an occupyin switch .(not shown) to the private wiper 4 thence over the conductor 101, through the back-release relay 70, side switch wiper '50,contact point 59,

private magnet 52 to the battery lead 90,

private magnet 52, when 'thus energized, locks the side switch in second position, and

"the wiper 51 in engagement with the contact point 60, whereby the rotary magnet 68 will be energized step-by-step until the wipers are carried beyond the last busy trunk-line.

At the instant thatthe private wiper leaves I the last busy contact point the energizing switch passes to third position. If, however,

circuit through the private magnet 52is destroyed, and asa result the selector side there are no busy trunk lines the rotary magnet 68 releases the side switch to third position as soon as the wipers are carried into engagement with the first trunk-line. As soon as the side switch passes to third position, as stated, the subscribers line-conductors 33 and 34 are extended to the conductors 98 and 99'which, inthis case, it is assumed lead to the ring-back arrangement D. The extending of the line occurs, of course, as soon as the side switch wipers 48 and 49 engage the contact points 61 and 62, respectively. Not only is the subscribers line thus extended, but a guarding potential is seizure by other su scribers. It will be seen,

of course, that the energizing circuit for the rotary magnet 68, to which reference has already been made, is destroyed when the idle trunk-line is seized-that is, when the sequence.

side switch wiper 51 leaves the contact point- 60. The calling subscriber has new extended the conductors 33 and 34"to the ring-back arrangement shown at'D, and the central oflice switches occupy the position indicated in Fig. 1. To signal the subscriber at substation A the calling subscriber at substa'v tion A presses the signaling button 29,. whereby an energizing circuit is established through the vertical relay of the ring-back through the windings 36 and 37 of the i arrangement, extending from ground G double-wound relay 35, conductor 102,'contact point 32, push-button spring 30, through thesprings 17 and 16, through the calling device springs to the vertical line con- .ductor 33, through the side switch-wiper 48, shaft wiper 45, trunk-line conductor 98, vertical line relay 79, winding 81 ofthe differential relay 83 to the battery lead 90, thence through battery B to ground G. This circuit provides energizing current for the, relay 35, which operates to disengage the springs 38 and 39 and to close the springs 40 and 41 in contact. When the springs 40 and 41 engage, a new circuit is established, shunting orshort circuiting the high resistance winding 36. Thisnew circuit is the same as the old' 'circuit, except that the high resist ance winding 36 is shunted or short-circuited. The winding 37 is provided in order to maintain the relay 36 energized after the winding 36 is 'short-circuited. When. the winding 36-is included in series in the circuit, sufiicient current doesnot fl'ow to oprelay operates, sufficient current then flows 'eratively energize the relay 7 9; but when't .this winding 36 is short-circuited, after the to operatively energize the vertical line'relay 79; and also,.since the winding 81 is included in this circuit, the relay 83 operates,.

but this operation at this time is-of no .con-

The relay 79, upon energizln'g, closes the springs 103 and 104 in contact,

" whereby an energizing circuit is established through the ringer relay 85, extending from" ground G atlthe selector C, through the Y side switch wiper 50, back-release relay .70

to-the private wiper 47, conductor 100,

through the springs 105 and 106, through the ringer relay 85, springs 104 and 103, through the dead resistance coil 84 to the battery lead 90, thence through battery B to' ground G. Theringerrelay 85, upon ener- -gizing, operates to shift the spring 107 from the spring 108 to the spring 109; also, the spring 110 is carried intov'engagement with the spring 111. By the operation of this relay the terminals of the ringer generator E are bridged across the extended line conductors 33 and 34,. whereby ringing current .is permitted to flow from the rotaryline conductor 34 to the conductor 113, and then 7 I through the ringers 114 and 115 in multiple with the substations A and A to the vertitary line conductor 34,. if the calling subscriber presses his signaling button after the called subscriber has removed hlS receiver from the switch-hook, and then to the rotary line relay 80 of the ring-back arrangement,

thus energizing both the vertical and rotary line relays simultaneously, whereby the re lease of the central office apparatus would be brought about. To prevent the possibility of a premature releasebeing brought about in this manner, the relay is providedfor opening up the rotary line conductors, and thus preventing the ground potential at the vertical line conductor from passing through a subscribers station to the rotary line conductors. The subscriber at substation A, in response to his signal, which may be two rings, removes his receiver from the switch-hook and bridges his primary circuit across the main line conductors 33 and 34, in multiple with the primary circuit of the substation A. Talking battery current for these two multiple primary circuits is established over a circuit extending from ground Gr through the springs 118 and 119, through the winding 82 of the relay 83, ro-

' tary line relay 80, ringer relay springs 108 and 107, through the conductors 99 and 34, springs 39 and 38, then through the primary windings 20 and 17, transmitters 18 and 116 to the vertical line conductor 33, side switch wiper 48, shaft wiper 45, conductor 98,

through the vertical line relay 79 and wind ing 81 of the differential relay 83 to the battery lead 90, thence through battery B to ground G. The windings 81 and 82 of the relay 83 are so arranged that when .both windings carry current, as before explained, the said relay does .not operatively energize; also, the relays 79 and 80, which are included in the talking circuit, are so arranged and adjusted that they do not operate when included in the talking circuit. The two substations being thus provided with talking current, conversation may be carried on in the well-known manner. After the subscribers have finished their conversation the subscriber who first restores his receiver to the switch-hook brings about the release of the central ofiice switching apparatus, as follows: Suppose subscriber A restores his receiver first. In that event the cam-arm 4 presses the release springs 7., 8 and 9 into assists the winding 81 in maintaining the relay 83 in an operated position. The energizing circuits through the windings 81 and 82 extends from the substation ground G through the springs '14 and 15, through the release springs 7, 8 and .9 to the vertical and rotary line conductors 33 and 34, then on one side over the vertical line conductor to the side switch-wiper 48, shaft wiper 45, trunk conductor 98, through the vertical relay 79 and winding 81 to the battery lead 90, thence through battery B to ground G; and on the other side the circuit over the rotary line extends from the conductor 34, through the side switch wiper 49, shaft wiper 46, conductor 99,through the ringer springs 107 and 108, through the rotary relay 80 and winding 82, through the springs 119 and 120 to the battery lead 90, thence through battery B to ground G. The vertical and rotary line relays 79 and 80 now operatively energize to place the springs 103, 104 and '47, conductor 100, springs 105, 104 and 103,

resistance coil 84 to the battery lead 90, thence through battery B to ground G. The back-release relay 70, upon energizing, places the springs 122 and 123 in. contact, whereby an energizing circuit is in turn provided for the release magnet 69, this circuit extending from ground Gr through the springs 122 and 123, and through the release magnet 69 to the battery lead 90, thence through batteryB to ground G. All of the relays and magnets thus energized attract their respective armatures and remain in readiness to return to normal position as soon as the ground to the main line conductors is broken, when the release springs 7, 8 and 9 disengage. v If the subscriber at substation A, however, desires to establish connection with a subscriber on some other line, the selector C is operated to seize some idle trunk-line leading to a connector, or to another selector, and finally to a connector which is operated to establish connection directly with the desired line. For example: To call the number 320 (substation, A the subscriber at substation A removes his receiver from the switch-hook and operates the callingknown manner. When the device is operated for thefirst digit the first-selector switch is operated to establish connection with an'idle trunk-line leading to the connector switchF. The impulses for the last two digits are directed toward the connector responding tothedesired line. The first the vertical line relay 65 of the first-selector:

j the vertical line relay v 90, as previously, explained The vertical linerelay in turn'op'erates to energize the before, and the private magnet in turn op;

side switch: frdm. first to whereby the rotary magnet becomes energized and, the shaft wipers 45, 46 and 47 are operated to sele'ct anlidle' .C .is energized-each time 'by a flow of cure substation ground. through.

rent from i t 65 to the battery lead vertical magnet 66,, whereby the shaft wipers are raised opposite the bank contaets of the third level. Following the vertical impulses the rotary line relay 67 is energized'as erates to carry the second positlon,

trunk-line leading to the connectpr switch F. The grounding of theline conductors 33' and 34 for the last two digits affects the connector by operating the vertical and rotary line relays 127 and 128.. When the vertical line conductor 33 is grounded the-vertical.

' vertical line conductor shaft wiper 45, trunk conductor 153, ver-' 1 line relay 127 is energized .by aflow of currentfromsubstation ground G through the.

33, side switch wiper 48, tical. line relay 127 winding 141 of the relay 140 to the battery lead 90-, thence through 1 third position a guarding potential is estabbattery B to ground G. The winding-141 of the relay 140 being included in this circuit but this operation is the said relay energizes,

. Each without effect at this particular time.-

time that the vertical line relay 127 operates for the second digit the vertical magnet 129 energizes to carryv the shaft operatively 125 and 126 in a vertical direcwipers 124,

" .tion 'one step at a time until the said wipers are carried two steps and. thus brought op-i .posite a level nals of the line #320. The circuit through in which are located the termi the vertical magnet 129 extends from ground G through the springs154 and 155, private magnet springs wiper 136, vert cal magnet 129 to the battery lead 90, thence through battery B to ground When the rotary line conductor 234 is vertical line conductor, the connector rotary grounded, following the grounding of i'the line relay 128'becomes energized through a circuit from ground G to the rotary line I conductor 34, side switch wiper 49, shaft wiper 46, rotary trunk conductor 158, rotary line re- 1 lay 128, winding 142 of the difierential relay device once for each digit inthe well 3 the spring 26 is'pressed onto Asa result" lay operates,

shaft wipers 124 and. 125

156 and 157, side switch memes batterylead ound G.

90, thence through battery 13 to V The kwinding 142 of the difi'erential relay 140 being included in this circuit, said relay 140 energizes, but with no eflect. The rotary line relay 128, upon energizing, operates to close anenergizing'c1rcuit, through the private" magnet 131, which latter in turn operates torelease the side 'switch from first to second position; For

as previously described, Q grounding the vertical line conductor33 ten.

the last digit the subscriber operates the calling device,

times and the rotary line conductor 34 once.

The vertical and rotaryline-relays 127 and .123 are 0 erated over previously traced cir- -.cu1ts. owever, whenthe vertical line rea circuitis closed through the rotary magnet. 130instead of through the vertical magnet .129, since the side switch wiper 136 is'now in second-position. Each time that the rotary magnet senergized the shaft wipers .124, 125 and'126 are rotated one step at a time until the said wipers are carried into',-engagement with .the normal conductors 1'61, 162 and 163, the first two of swhich lead: to the lineterminals of the-de-g I sired substationj The rotary: line relay 128,

upon energizing, completes? an energizing circuit through the-private magnet 131 as 4 before, which latter now operates with one of two results, namely the release of the side switch; from first to second position, or the '.so-calledbusyrrelease of the connector. It

will be assumed that the former result occurs, and that the side switch position, whereby theside switch wipers 134 passes to third and 135 are. placed in connection with the respectively. Furthermore, when the .side switch passes to lished for protecting "the called line. This nalingbutton 29, whereby the vertical line conductor 33 is grounded, and the connector vertical line relay 1.27 and the differential relay '140 becomev energized as before. It will be assumed ,that the side switch has passed from second to third position, and

that the side switch wiper'136 is in"eng agement with athird-position contact point, thereby placing the vertical line relay 127 in control of the ringer relay 144 in the same manner in which the rotary magnet 130 cameunder the control of the vertical line relay when the'side switch'passed from first to second position. Therefore, .when the vertical line relay presses the springs 154 and 155 into contact the ringer relay 144 is energized from. ground G51 through the 156 and 157, side switch wiper 136, ringer springs 154 and private ma et 5 rin 140, through the springs 159 and 160 to the 7 gm P gs relay 144, springs 164 and 165 (bearing in mind that the differential relay 140 is energized) to the battery lead 90, thence through battery 'B'to ground G. The ringer relay,

'upon-energizing, operates to bridge the terminals of the ringer generator'E across the conductors of the desired line; A signaling r cu" rent is therefore sent from the ringer i the switch-hook, whereby the switch-hook rises, permitting the springs 167 to disengage and the springs 168 to engage, thereby removing the ringer-166 from across his line and bridgin instead the transmitter and primary win ing. When the primary winding and transmitter come across the line anenergizing circuit is established throughboth windings of the relay 143 extending from ground Gr through'the side switch wiper' 137, through the winding 146 of the relay 143, through the ringer relay springs and side switch wiper 135 to the rotary normal conductor 162, rotary line conductor 169, throu h the primary win ing and transmitter to the vertical line conductor 170, vertical normal conductor 161, shaft wiper 124 and side switch Wiper 134,

through the winding 145 of the relay 143,

through the springs 171 and 165 to the battery lead 90, thence through batteryB to, ground'G. The'relay143, upon energizing, operates to shift the spring 159 from the spring 160 (which latter is connected with the battery lead 90) to the spring 17 2, which in turn is connected with ground. The re- ,versal of polarity of the spring 159 sets up a circuit which provides the calling 'subscriber with battery current for talking purposes. This current may be traced from ground G through the side switch wiper 137, sprin s '172 and 159, through thewinding 142 o the relay 140, rotary line relay 128, conductors-158 and 34, through the primary windi'n and transmitter of substation A to the vertical line conductors 33 and 153, vertical line relay 127, winding 141 of the diflierential relay 140 to the battery lead 90,

thence through battery B, to ground G.- Both windings of the relay 140 now carry current, but the windings are so arranged that the said relay-does not operatively energize. The vertical and rotary line relays 127 and 128 being included in the above c1r-- cuit operatively energize and place their springs in contact, and the release springs 173 and 174 are also brought into contact,,

f but the simultaneousaction of these relays at this particular time is without effect, since no energizing circuits are established thereb The two substations A and A being tlius provided with battery current for talking purposes, conyersation may be carried on over circuies shown by the heavy line I and 34, through the release 7 to the substation ground conductors in Figs. 1 and 3. The release of the central office switching apparatus is brought about when the calling subscriber restores the receiver 2 to the switch-hook 3,

thereby pressingthe release springs 7, 8 and 9 into engagement for a moment. The contact of the said release springs grounds the vertical and rotary line conductors 33 and 34 1 simultaneously from ground G rto the release spring 7, thence through the springs 8 and 9 to the vertical and rotary line conductors. The grounding of the rotary line conductor 34 produces'a short-cirouit of the rotary line relay 128 in series with the winding 142 of the differential relay 140. The

said circuit extends from'ground Gr at'the connector to the side switch wiper 137,

springs 172 and 159, through the winding spring 160, which removes the said shortcircuit of the rotary line relay 128 and windits armature,

'95 spring 172 and into engagement with the ing 142 and establishes an energizing circuit instead from the substation ground 'G? through the release springs 7, 8 and 9 to the rdtary line conductor 34, thence to the rotary line relay 127, as previously traced, winding 142 of theldifl'erential relay 140, through the springs 159 and 160 to the battery lead 90,

thence through battery B to ground G. The rotary line relay 128 now operates and the springs 173 and 174 come into contact, whereby an energizing circuit is established 5 through the release magnet 132 of the connector F and the release relay 70 of the selector 0. However, the current now in passing, as above stated, through the winding 142 aids the winding 141 in maintaining the springs 164 and 165 in contact. The energizing circuit through the release magnet 132 extends from round G at the selector C through the si e switch wiper 50, back-release relay '70, shaft wiper 47,conductor 175, through'the release springs 173 and 174, release magnet 132, springs 164 and 165 to the battery lead 90. thence through battery. B to ground G. The connector, release magnet, upon being supplied with current, energizes,-and as a result the switch shaft and sideswitch are restored tonormal condition, thus breaking the connection between the connector switch shaft wipers 124,

125 and 126 and the normal conductors 161,

1.62 and 163. The back-release relay' 70 being in the same circuit with the-release magnet 132 energizes simultaneously with the latter, and operates to close the circuit through the release magnet 52 of the selector C by pressing the back-release springs 122 and 123 together. The circuit through the release magnet 69 extends from ground G through the springs 122 and 123, and

' through the release magnet 69 to the battery lead 90. l/Vhen the ground to the line conductors 33 and 34: is interrupted, all the magnets involved in the release are deenergized and all switches fully restored.-- If the called line #320 is busy at the time that the calling subscriber attempts to establish con nection, the connector F is released by the private magnet springs 176 and 177 arebrought into contact an energizing circuit is established through the release magnet 132 from the said grounded private bank contact to the private wiper 126, thence to the side switch wiper 137 (which is in second position), through the private magnet springs 176 and 177, through the winding of. the release magnet 132, springs 164 and 165 to the battery lead 90, thence through battery B to ground G. The connector switch shaft and side switch are thus released, and con nection is not established with the called line. Now, when the calling subscriber presses the signaling button the vertical line relay 127 becomes energized and operates to close the circuit through the vertical magnet 129. The vertical magnet operates to carry the vertical shaft vertically, whereby the off-normal springs 151and 152 engage to permit a busy-signaling current to pass to the called subscriber in the usual way. Of course, when the subscriber hangs up his receiver after receiving the busy-signal, he grounds the line conductors 33 and 34:, as already explained, producing the release of the switching apparatus as formerly.

From the foregoing it will be seen that I provide a common battery system in which party-line subscribers uniformly call the subscribers on the same line by a single movement of the calling dial. In other words, the special ring-back arrangement, such as shown at D, is reached by the first selector as a result of the numerical opera- .to which the ring back. is allotted.

tion of the dial to find the particular level After the level is found; lhowever, the selector switch, as the result of a non-numerical op eration, is automatically connected with the ring back which visexclusively for calling between subscribers on'the same line. fThe ordinary common battery connectors hav= ing ringer relays can be employed for calling and signaling between different lines..

The said ring-back arrangement not only controls the flow of both ringing and talking currentto the substations of the party-line, 7

but also controls the trunk-release circuit extending back through the first-selector, in 1 Q the manner explained.

In the modification shown in common relay 35is omitted .In this system the ring-back arrangement is identical with that shown at D in Fig. 1, but the substation circuit is necessarily changed slightly. In the substations shown in Fig. 2 the ringer push button spring 32 is connected to ground through the-springs 15 and 14 instead of through the relay 35, and the ringer circuits in Fig. 2 connect with the rotary line in the various substation instrumen-ts, and not at the relay 35 as isthe case in Fig. 1. Fig. 2 only two conductors are required between the difierent substations on a line.

When the relay 35 is omitted-the release of opening of the rotary line at the springs 108 and 107 of the ringer relay 85. If, however, the signaling button at the calling substation is again pressed after the called subscriber has removed his receiver, the exchange apparatus might be prematurely released if the relay 35is not used.

What I claim as my invention is '1. The combination, in a telephone system, of a party-line, a plurality of subscribers stations on said line, a ringing apparatus, automatic selectors having one contact level thereof adapted for automatically extending said line into connection with said ringing apparatus, and having other levels thereof adaptedfor service in'calling subscribers on other lines, subscribers trans- Knitters connected to receive current for talking purposes from the exchange or central station and means for transmitting ringing current from said ringing apparatus via said selectors to said line.

2. The combination, in a telephone system, of a party-line, a plurality of subscribers stations located on said line, a special party-line ringing apparatus used only when one subscriber is calling another upon the Fig. 2 the With the apparatus shown in same line, automatic means for connecting said line directly with said ringing apparatus to enable one subscriber to call another on the same line, subscribers transmitters connected to receive current for talking purposes from the exchange or central station, and means for transmitting ringing current/from said ringing apparatus via said automatic means.

3. The combination, in a telephone system, of a party-line, a plurality of subscribers"stations located on said line, other lines, means including automatic connectors for calling from one line to another, means including a special ringing apparatus independent of said connectors, adapted for enabling one party-line subscriber to call another on the same line, without using said connectors, subscribers transmitters connected to receive current for talking purposes -from the exchange or central station, said first means comprising a switch for ex-. tending connection to said ringing apparatus and means for transmitting ringing current from said ringing apparatus via said switch to the said line. L. The combination, in a telephone system, of a subscribers telephone line, automatic means for trunking calling lines into connection with called lines, a plurality of subscribers stations on one or more of said lines, an automatic ringing apparatus exclusively for use between calling and called subscribers on the same line, subscribers transmitters connected to receive current for talking purposes from the exchange or central station, said-automatic means comprising a switch for extending connection to said ringing apparatus, and means for transmitting ringing-current from said ringing apparatus via said switch to the said line.

'5. The combination in a telephone 'system, of a party-line, a plurality of subscribers stations on said line, a rotary calling dial for each subscribers station, adapted to come to rest after operation thereof for each digit of the called number, means including automatic switches whereby one subscribers line can be connected with another line, automatic means by which subscribers on the same line uniformly call each other by a, single movement of the dial, and subscribers transmitters connected to receive current for talking purposes from the exchange or central station.

6.-The combination, in a telephone sys- I tem, of a party-line, a plurality of subscribers stations located on said line, other lines, a calling dial for each subscribers station, means necessitating a plurality of movements of the dial when a party-line subscriber calls a subscriber of some other line,

automatic means by which subscribers on the same line uniformly call each other by a single movement of the dial, and subscribers transmitters connected to receive current for talking purposes from the exchange or central station.

7. The combination, in a telephone system, of means for signaling between subscribers on the same line, said means comprising a pair of line relays, a ringer relay governed by one of said line, relays, an automatic switch and a release circuit therefor controlled by the energizing of the linerelays simultaneously, subscribers transmitters connected to receive current for talking purposes from the exchange or. central station, means for extending said line to said signaling means, and means for transmitting ringing current, from said signaling means via said connecting means to said line.

8. The combination, in a telephone system, of means for. signaling between subscribers on the same line, said means comprising a pair of line relays, a ringer relay governed by one of said relays, a source of ringing current adapted to be connected for ringing said line relays, subscribers transmitters connected to receive current for talking purposes from the exchange or central station, means for extending said line to said signaling means, and means for transmitting ringing current from said signaling means via said connecting means to said line.

9. The combination, in a telephone system, of means for signaling between subscribers on the same line, said means comprising a pair of line relays, a battery to one pole of which the windings of said relays are connected in multiple, a ringer mechanism governed by one of said line relays, an automatic switch and a trunk-release circuit therefor controlledjby the energizing of the line relays simultaneously, subscribers transmitters connected to receive current for talking purposes from the exchange or central station, means for extending said line to said signaling means, and means for transmitting ringing current from said signaling means via said connecting means to said line.

10. The combination, in a telephone system, ofmeans forsignaling between subscribers on the same line, said/means comprising a pair of line relays, a batte to one pole of which the windings of sai relays are connected in multiple, a ringer mechanism governed by one of said line relays, an automatic switch and a trunk-release circuit therefor controlled by the energizing of the line relays simultaneously, means for extending connection to said signaling aim for bridging said battery across the line cir cuit to supply current for talking purposes to calling and called stations on the same line. 7 I V 11. The combination, in a telephone system, of a party-line, a plurality of subscribers stations on said line, a ringing apparatus, automatic selectors having one level thereof adapted for automatically extending said line into connection with said ringing apparatus and having other levels thereof adapted for other service, ringers at said stations, each ringer connected via a condenser-to one-side of the line and switch hook controlled means 'for disconnecting each ringer separately from the other side of said line, and means for transmitting ringing currentfrom said ringing apparatus to said line via said selectors.

12. The combination, in a telephone system', of a party-line, a plurality of subscribers stations located on said line, a ringing apparatus, au'tomaticmeans for extending said line directly to said ringing apparatus to enable one subscriber to call another on the same line, ringers at said stations, each ringer connected via a condenser to one side offthe line and switch hook controlled means for disconnecting each ringer separately from the other side of said line, and means for transmitting ringing current from said ringing apparatusto said line via said automatic means. v

1.3. The combination, in a telephone system, of a party-line, a plurality of subscriber's stations located on said line, other lines, means including automatic connectors for calling from one line to another, a special ringing apparatus independent of said connectors and adapted for enabling one partyline subscriber to call another on the same line, ringers in said stations, each ringer connected via a condenser to one side of the line and switch hook controlled means for disconnecting each'ringer separately from the other side of said line, and means for extending said line to said ringing apparatus, whereby said apparatus may transmit ringing current to the calling line via said last denser to one side of the line and switch hook controlled means for disconnect-ing each ringer separately from the other side of the line.

tem, of a subscribers telephone line,,auto-' V matic means for trunking calling lines into connection withccalled lines, a plurality of subscribers stations on one or more of said lines, an automatic ringing apparatus exclusively for use between calling and called sub scribers on the same line, means for extending connection from one of saidlast lines to said automatic ringing apparatus, and means for transmitting signaling current from said ringing apparatus via said extending means to said last line, ringersat said stations, each ringer connected via a condenser to one side of the line and switch hook controlled means for disconnecting each ringer separately from the other side of said line."

16.-The combination, in'a telephone system, of a party-line, a plurality of subscribers stations on said line, a calling. dial for each subscribers station, automatic means by which subscribers on the same line uni- V formly call each other by a single movement of the dial, ringers at said stations, each ringer connected via a condenser to one side of the line and switch hook controlled means "for disconnecting each ringer separatel from the other-side of said line. a .1

17. The combination, in a telephone system, of a party-line, a plurality ofsubscribers stations located on said line, other lines, a calling dial for each subscribers station, means necessitating a 'plurality of movements of the dial when a party-line subscriber calls a subscriber of'some other line,

automatic means by which subscriber's on the same line uniformly call each other by a single moveinent of the dial, ringers at said stations, each ringer connected via a condenser to one side of the line and switch hook controlled means for disconnecting each ringer separately from the other side of said line. 0

18. The combination, in a telephone system, of a special ring-back arrangement, comprising a pair of line relays, means for reaching the said arrangement, a ringer re: lay governed by one of said line relays tosend ringing current back over "said means for signaling between subscribers on the same line, a release circuit for said means controlled by the energizing of the line re-' lays simultaneously, ringers at said stations, each ringer connected via a condenser to one side of the line and switch hook controlled means for disconnecting each ringer separately from the other side of said line.

19. The combination, in a telephone system, I

of a device for signaling between subscribers stations on the same line, said device com- ,prising a pair of line relays, means including an automatic switch for reaching said device, abattery to one pole of which the winding of said relays are connected in multiple, a ringer mechanism governed by one of said line relays to send ringing current back over said means for signaling between subscribers on the same line, a trunkrelease circuit for said switch controlled by the energizing of the line relays simultaneously, ringers at said stations, each ringer connected via a condenser to one side of the line and switch hook controlled means for disconnecting each ringer separately from the other side of the line. 20. The combination, in atelephone system, of a party-line, a plurality of subscribers stations located on said line, an automatic switch controllable from anyone of said stations, trunks having terminals in said switch, one or more of said terminals appropriated exclusively for calling between subscribers on the same line, means for controlling said switch to extend a connection oven said trunks for signaling back over said switch, ringers at said stations, each ringer connected via a condenser to one side of said line and switch hook controlled means 'for disconnecting each ringer separately fromthe other side of said line, a test circuit for oneof said trunks, and means in the automatic switch controlled over said test circuit for causing the switch to move away from the terminals of one of said' trunk terminals, one level of said bank being appropriated exclusively for calling between subscribers on the same line, means for controlling said switch to extend a connection over sai said switch, ringers at said stations, each ringer connected via a condenser to one side -of said line and switch hook controlled line.

means for disconnecting each rin er separately from the other side of said ine, test circuits for said trunks, and means in the automatic switch controlled over said test circuits for causing the switch to move away from the terminals of one of said trunks. I

22. The combination, in a telephone system, of a party-line, a plurality of subscribers stations located on'said line, a ringing apparatus, automatic means for connecting said line directly with said ringing apparatus to enable one subscriber to call another on the same line, and a relay for opening one side of the party-line when one sub-' scriber thereon rings another on the same .23. The combination, in a. telephone system, of a party-line, a plurality of subscribers stations located on said line, other lines, means including automatic connectors for calling from one line to another, a special'ringing apparatus independent of said connectors and adapted for enabling one trunks for signaling back over,

party-line subscriber to call another on the same line, and a relay for opening one side of the party-line when one subscriber thereon rings another on the same line.

24. Thecombination, in a telephone system, of a party-line, a plurality of subtem, of a subscribers'telephone line, auto-.

matic means for trunking calling lines into connection with called lines, a plurality of subscribers stations on one or more of said lines, an automatic ringing apparatus exclusively for use between calling and called subscribers on the same line, and a relay for opening one side of the party-line when one fubscriber thereon rings another on the same 7 26. The combination, in a telephone system, of a party-line, a plurality of subscribers stationson said line, a calling dial for each subscrlbers station, automatic means by which subscribers on the same line uniformly call each other by a single movement of the dial, and a'relay for opening one side of the party-line when one subscriber thereon rings another on the sameline. Q, l

27. The combination, in a telephone system, of v a party-line, a plurality of subscribers stations located on said line, other lines, a calling dial for each subscribers station, means necessitating a plurality of movements of the dial when a party-line subscriber calls a subscriber of some other line, automatic means by which subscribers on the same line uniformly call each other by a single movement of the dial, and a relay for opening one side of the party-line when one subscriber thereonrings another on the same line.

28. The combination, in a telephone sys tem, of a special ring-back arrangement for signaling between subscribers on the same line, comprising a pair of line relays, a ringer relay governed by one of said line relays, an automatic switch and a release circuit therefor controlled by the energizing of the line relays simultaneously, and a relay for opening one side of the party-line when one subscriber thereon rings another on the same line. .1

29. The combination, in a telephone system, of, a special ring-back arrangement for signaling between subscribers on the same line, comprising a pair of line relays, a ringer relay governed by one of said relays, a source of ringing current adapted to be connected for ringing by the energizing of the ringer relay, an automatic switch and circuit therefor controlled by the simultaneous energizing of said line relays for controlling the switch, and a relay for opening one side of the party-line when one subscriber thereon rings another on the same line.

30. The combination, in a telephone system, of a special ring-back arrangement for signaling between subscribers on the same line, comprising a pair of line relays, a battery to one pole of which the windings of said relays are connected in multiple, a ringer mechanism governed by one of said line relays, an automatic switch and a trunkrelease circuit therefor controlled by the energizing of the line relays simultaneously, and a relay for opening one side of the party-line when one subscriber thereon rings another on the same line.

31. The combination, in a telephone system, of a party-line, a plurality of subscribers stations located on said line, an automatic switch controllable from any one of said stations, trunks having terminals in said switch, one or more of said terminals appropriated exclusively for calling between subscribers on the same line, and a relay for opening one side of the party-line when one subscriber thereon rings another on the same line.

32. The combination, in a telephone system, of a party-line, a plurality of subscribers stations located on said line, an automatic switch provided with a bank of trunk terminals, one level of said bank being appropriated exclusively for calling between subscribers on the same line, and a relay for opening one side of the party-line when one subscriber thereon ringsanother on the same line.

33. The combination, in a telephone system, of a party-line, a plurality of subscribers stations on said line, a ringing apparatus, automatic selectors having one level thereof adapted for automatically extending said linetinto connection with said ringing apparatus and having other levels thereof adapted for other service, and a relay adapted for opening one side of the party-line and provided with means for short-circuiting a portion of its own resistance when energized by current from the central station.

34. The combination, in a telephone system, of a party-line, a plurality of subscribers stations located on said line, a ringing apparatus, automatic means for connecting said line directly with said ringing apparatus to enable one subscriber to call another on the same line, and a relay adapted for opening one side of the party-line and provided with means for short-circuiting a portion of its own resistance when energized by current from the central station.

35. The combination, in a telephone system, of a party-line, a plurality of sub scribers stations located on said line, other lines, means including automatic connectors for calling from one line to another, a special ringing apparatus independent of said connectors and adapted for enabling one partyline subscriber to call another on the same line, and a relay adapted for opening one side of the party-line and provided with means for short-circuiting 'a portion of its own resistance when energized by current from the central station.

36. The combination, in a telephone sys tem, of a party-line, a plurality of subscribers stations located on said line, other lines, means necessitatinga calling of the called subscribers number. in calling from one line to another, means for enabling one party-line subscriber to signal another subscriber on the same line responsive to impulses differing in number from those corresponding to the number of the latter, and a relay adapted for opening one side of the party-line and provided with means for' short-circuiting a portion of its own resistance when energized by current from the central station. p

37. The combination, in a telephone system, of a subscribers telephone'line, automatic means for trunking calling lines into connection with called lines, a'plurality of subscribers stations on one or more of said lines, an automatic ringing apparatus exclusively for use between calling and called subscribers on the same line, and a relay adapted for opening one side of the partyline and provided with means for short-circuiting a portion of its own resistance-when energized by current from the central station.

38. The combination, in a telephone sys tem, of a party-line, a plurality of subscribers stations on said line, a calling dial for each subscriberfs station, automatic means by which subscribers on the same line uniformly call each other by a single movement of the dial, and a relay adapted for opening one side of the party-line and pro-- vided with means for short-circuiting 'aportion or its own resistance when energized by current from the central station. 7

39. The combination, in a telephone system, of a party-line, a plurality of sub scribers stations located on said line, other lines, a calling dial for each subscribers station, means necessitating a plurality of movements of the dial when a party-line subscriber calls a subscriber of some other line,

automatic means by which subscribers on I 45 .means for short-circuiting a portion of its adapted for opening one side of the party-' w energized by current from the central station.

4:0. The combination, in a telephone sys tem, of a special ring-back arrangement for signaling between subscribers on the same line, comprising a pair of line relays, a ringer relay governed by one of said line relays, an automatic switch and a release circuit therefor controlled by the energizing of the line relays simultaneously, and a 1'6? lay adapted for opening one side of the party;line and provided with means for short-circuiting a portion of its own-resistance When energized by current from the central station.

tem, of a special ring-back arrangement for signaling between subscribers on the same line, comprlslng a pair oflline relays, a.

ringer relay governed by one of said relays, a source of ringing current adapted to be connected for ringing by the energizing of the ringer relay, an automatic switch and a circuit therefor controlled by the simultaneous energizing of said line relays for controlling the switch, and a relay adapted for opening one side of the party-line and provided with means for short-circuiting a portion of its own resistance when energized by current from the central station.

42. The combination, in a telephone system, of a special ring-back arrangement for signaling between subscribers on the same line, comprising a pair'of line relays, a battery to'one pole of which the windings of said relays are connected in multiple, a ringer mechanism governed by one of said line relays, and automatic. switch and a trunk-release circuit therefor controlled by tion? the energizing of the line relays; simultaneously, and a relay adapted for opening one side of the party-line and provided with own resistance when energized by current from the central station./

43. The combination, in a telephone system, of a party-line, a plurality of subscribers stations located on said line, an automaticswitch controllable from any one of I said stations, trunks having terminals in 'said switch, one or more of said terminals 7 appropriated exclusively for calling between I subscribers on the same line, and a relay adapted for opening one side of the party- 'line and provided with means for short-circuiting aportion of its ownresistance when energized by current from the central sta- 44.- The combination, in a telephone system, of a party-line, a plurality of SlJbSCI'lb- ,ers stations located on said line, an automatic switch provided W1th a bank of'trunk only at a certain level for ringing back over said switch, a common battery for talking purposes, and means for controlling the operation of said switch.

46. In a telephone system, a party-line, means including an automatic switch for calling'backon said line, means for releas- 41. The combination, in a telephone sysa subscriber, and a relay adapted to be energized during signaling to open the opposite side of said line to prevent the release of said switch.

48. In a telephone system, a line, a 111- rality ofsubscribers stations on said ine, means for grounding one side of said line to signal a subscriber, a relay adapted to be energized during signaling, and means controlled by said relay for opening the oppo- 1 site side of, said line during the signaling operation to enable one subscriber on said line to signal another subscriber thereon. i

49. In a telephone system, a subscribers.

line, means for grounding one sideof said 11 0 line to signal the subscriber thereon, a relay having a pair of energizing windings adapted to1be energized during-signaling, and means controlled by the operation /of said relay for opening the opposite side of said 115 line and for short-circuiting one of the? windings of said relay. I

50. The combination, in a telephone system, of a special ringing arrangement comprising a pair of line relays, means comprising a progressively movable switch for reaching the said arrangement, a ringing relay governed by one of said line relays to send ringing current back over said means for signaling between subscribers stations on the same line, a circuit for said means controlled by the simultaneous energizing of said line relays for controlling the switch,

ringers at said stations, each ringer connected via a condenser to one side of the l1ne and switch hook controlled means for disconnecting each ringer separately from the other side of said line. I

V 51. In a telephone system, the combina-. tion of a line, a plurality of subscribers stations on said line, a ringing apparatus, progressively movable central ofiice equipment for said line for establishing connection with said ringing apparatus, said ringing apparatus comprising means for-sending ringing current only to the calling line, a central battery, subscribers transmitters one for each station, said'transmitters connected to receive current for talking purposes from said central battery.

52. In a telephone system, the-combina: tion of a line, a plurality of subscribers stations on said line, a ringing a paratus, progressively movable central 0 cc equipment for said line for establishing connection with said ringing apparatus, said rmgmg apparatus being ready to send ringing current only to the calling line as soon as it is seized by the said switch, and subscribers said-line, and subscribers transmitters connected to receive current for talking purposes from the exchange or central stat on.

54:. In a telephone-system, the combination of a line, a plurality of subscribers stations on said line, a source of ringing current, automatic means for extending a non-inductive connection from said line to said source to enable one subscriber to signal another subscriber on the same line by transmitting signaling current from sald source via said automatic means to said line, and

subscribers transmitters connected to receive current for, talking purposes from the exchange or central station, a test circuit for said line and means controlled by said automatic means for applying a potential over said test circuit to guard the line against seizure,

55. In a telephone system, the combination of a line, a plurality of subscribers stations on said line, a ringing apparatus, progressively movable central ofice equipment for said line for establishing connec tion with said ringing apparatus, said ring-- ing apparatus comprising means for sending ringing current to the calling line, a central battery, subscribers transmitters, one for each station, said transmitters connected to receive current for talking purposes from said central battery, a test circuit for said line, and means controlled by said equipment for applying a potential over said test circuit to guard the line against seizure.

56. In a telephone system, the combination of'a line, a plurality of subscribers stations on said line, a ringing apparatus,

progressively movable central office equipment for said line for establishing connection with said ringing apparatus, said apparatus beingready to send ringing current to the calling line as soon as itis seized by the said switch, subscribers transmitters connected to receive current for talking puroses from the central station, a test circuit or said line, and means controlled by said equipment for applying a potential over seizure.

57. In a telephone system, a subscribers' line, an automatic switch associated with said line, said switch provided with means for signaling, means for grounding one side of said line to signal the subscriber, and means for opening the other side ofsaid line between the substation and the central ofiice for preventing the switch operating to rensaid test circuit to guard the "line against der the means for signaling inoperative dur:

ing said signaling.

58; Ihe combination in a telephone system of a line, a plurality of subscribers stations for said line, a transmitter for each station, a signal for each station connected to the-line,- an automatic switch associated with the line, means for controlling said switch from'any one of said stations, lines having terminals accessible to said switch,

means controlled over said lines for operating anyone of said signals, means for connecting the transmitter of any signaled station to the line, a centralbattery for supplyin current to any transmitter over said line or talking purposes, a test circuit for said line terminating in said: switch, said switch having means controlled over said circuit for causing the switch to move away from the terminals of said line.

59. 'The'combination, in a telephonevsystem, of a line, a plurality of subscribers stations for said line, a transmitter foreach station, a signal for each station connected to the line, an automatic switch associated with the line, means for controlling said switch from any one of said stations, said switch provided with a bank of terminals,

certain of said terminals being used for calling between stations on the same line, means controlled over said'trunk lines for operating any one of said signals, means for con trunk-lines terminating in said terminals, I

necting the transmitter of any signaled sta- 1 tion to the line, a central battery for supplying current to said transmitter over said line for talking purposes, a test circuit for said line terminating in said switch, said switch having means controlled over said I test circuit for causing the switch to move away from the terminals of said line.

60. In a telephone system, the combination of a plurality of lines, a plurality of stations on each'line, an auxiliary line, terminals for said auxiliary line, ringing apparatus controlled over said auxiliary line, progressively movable switching equipment for said lines having access to said terminals for establishing connections with said apparatus whereby said apparatus may be controlled over saidlines, said apparatus comprising means for sending ringing current to any one of said lines only over said terminals, and a central battery for supplying current to said lines for talking purposes.

61. In a telephone system, a two conductor line and a signal connected thereto, a two conductor trunk line, a switch controllable'over said first line for connecting the two lines, a pair of line relays, a double wound relay and a grounded battery all in series with the two conductors of said trunk line,. said relays normally inoperative, a source of signaling current, means under the control of one of said line relays for connecting said source to said trunk line to operate said signal, means for releasing said switch and a circuit for said means controlled jointly by said line relays, means controlled by said double wound relay for shifting one of its windings from the grounded to the ungrounded pole of said battery, and means for grounding one or both conductors of said line whereby the associated signal may be operated or the said switch released, substantially as described.

62. In a telephone system, the combination of a line, a plurality of subscribers 40 stations on said line, a ringing device including a source of ringing current, automatic means for extending connection from said line to said source of current to enable one subscriber to signal another subscriber on the same line after said automatic means is operated by transmitting signaling current from said source via said automatic means to said line, subscribers transmitters connected to receive current for talking p'urposes from the exchange or central station, and means for connecting said source of current across the line.

Signed by me at Chicago, Cook county, Illinois, this 14th day of September, 1907.

FRITZ LUBBERGER.

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