US1009813A - Telephone system. - Google Patents

Description

H. G. WEBSTER.

TELEPHONE SYSTEM.

APPLICATION FILED MAR. 7, 1907 1,009,81 3. Patented Nov. 28, 1911 2 SHEETS-SHEET 1.

H. G. WEBSTER.

TELEPHONE SYSTEM.

APPLICATION FILED man, 1907 1,009,813. Patented Nov; 28, 1911.

' 1 STATES PATENT oFFIoE.

HARRY G. WEBSTER; or cnrcaeo, ILL'I No s, ASSIGNOB, BY rinsnn ASSIGNMENTS, T

xELLoo'G swI'roIIBoAIm a sUrPLY coMraNY, a CORPORATION 0F. ILLINOIS.

iuliomit concern citizen ofthe'Unit'ed States,-residing at Chicage,imthe-county of=Cook and State of iiectlonivith-lhe desired called party to hold "tlief line to the exclusion of another who may (desire: to listen-in or to signal the operator fat thejcentral otiice, except in those cases withanother partyon thesame line. In the latter event, a specificact on the part of the calling subscriber coupled with the operation of ccrtaiumechanism at the central off[de ine tion-similar 7,1907. Serial K013613193 \vhere a calling party desires to .converse TELEPHONE SYSTEM.

' Specification of Hitters Patent. iv Patented Nov, 28, 19 11.

- Ill-L designate two telephone lines extending by' tiieir limbs '12 from substations to a central otlice; line L extending from substations A' A and being..pro-

equipment; "At the substation VallOilS'ClP- cuit arrangements may be employed. In the present figure, I'h'ave illustrated a welllmown substation circuit modified in accordance with the present invention. Inthis case, a transmitter 3 and a receiver 4 are included in normally open circuits which are control] d by the switch-hook 5 and a controlling electromagnet 6 whose winding is bfllllinois, have invented new and'useful'Imi ded with jacks J at. the centraL-of- 0 1provements in'TelephoneSystems, of which lice; and line L extendingfrom substations z-thefollowiug isa specification.f '1 B"B B B to the central oflice where iThe 'prese'nt'inyention elat'es to telephone they are providedwith jacks J -Obviously *sys'ter'ns'gene'rallykind more'l'iarticularly' to the number of substations on each of these 10,-pa1-t yline systems bfthe so calledh t-locklines may be varied. as conditions in any 5 outty'pc. i I V specific case may require. Interconnection "The-principal. object of the invention is between the jaek's JJ is accomplished to -devise a novel system of the type indithrough the agency of suitable link-circuits, I 'cated,"\vl1 ich in o'p eration will enableany such as L, provided with terminal plugs -17 6 th,-. 1i h ha obtained conand with the usual 'party line 0 rators 2 \fi bl th d ty to come in on also included in a normally open circuit 30 the line. 1 I adapted to be closed bythe switch-hook 5 The system which I have devised is espewhen the receiver 4 is removed therefrom. cially designed for use with a centralized A condenser 7 and call-bell 8 are included in or common source of battery supply and a normally closed bridge. The Substation! 30 with selective signaling, although obviously equipment also includes the usual induction the latter is not essential to "the practice f coil 9 and a control-key 10. The line limbs my invention. 1.! are normally connected. at the central In carrying out my invention 1 have deoiiice to the grounded and live poles revised certain novcl circuit arrangements spcctively of a section I) of a central office 35 both at the substation and at the central attery, the line limb 1 extending through office. The character of the invention howcontact 11 of cut-ofi relay 12 to ground, ever, will be more fully understood upon or other suitable common return, and the reference to the following detailed descripline limb 2 extending by way of the section taken inconnection with the accom- 0nd contact 13 of cut-01f relay 12, and

40'panying drawing, and the scope of the inthe winding of line relay 14 to the live,

- vention will be particularly pointed out in the ap ended claims.

In t e said drawing,-Figure 1 illustrates diagrammatically one system embodyin the features of the present invention; Fig. 2 illustrates by a similar diagram another system embodying the features of the invention and illustrates a. modified ar rangement of substation circuits and appaor negative, pole of the battery section b". The interconnecting link-circuits at its central ofiice, of which one only is shown, are of a well known three-wire type modified in accordance with the present invention. Thethreefcontacts of the answering plug P" form the terminals of strands 15-1617 whichare connected to the terminals of the section b of the central office battery. The strand15 is connected through the winding 18 of the repeating coil R to the grounded terminals of the battery Sections bb-. Strand 16 which is normally interrupted, is adapted to be connected through winding 19 of the repeating coil 5 ratus which may be used in'lieu of those illustrated in'either of the other fi res.

Throughout these views like cl ii racters refer to ike parts.

Referring In detail to the drawing and more particularly for the present to Fig. 1,

to the live, or positive, pole of the battery set-lion 6". Strand 17 is connected to the snlnti terminal of the battery section b through the resistance 20. The three,contucts of the callin plug P, located at we opposite end of tie link-circuit, form t e terminals of the three strands 212223 which have their op osite ends connected to the, terminals of the attery section b. The strand 21 extends through the ringing key lever 24 and winding 25 of repeating coil It to the grounded connection of the batto Strand 22. which is normally open, exten s through ringing-key lever 26 and is ada ted to be connected throu h winding 27 0 .repeating coil R to the live pole of the battery section Strand 23 in turn is adapted to be connected through resistance 28 to the same pole of battery section b. The supervisory lamps 2930 are included in the strands l7 and 23 respectively and are adapted to be controlled by the supervisory relays 3l'and 32 respectively. The associatod relays 33-34 are instrumental in reversing the direction of current supplied to the line from the central ofiice battery. The interconnecting link-circuit also includes an operators set S which includes transmitter 35 connected between the live pole of. the battery section b and ground at 36 and in a local circuit including condenser 37 and one winding of' induction coil 38, and the head receiver 39 adapted to be included in brid e of the link-circuit strands 2122 with t 0 other winding of induction coil 38v and a condenser 40. The operators set is thus cut into circuit by the listening-key levers 4142 and inductive resistance 43 is included in a connection between batter and the transmitter 35 for the urpose 0 conlrollin the supply of attery current througi the transmitter 35 while preventing the undue leakage of voice currents from the operators transmitter circuit. For the purpose of signaling the parties at the ditl'erent substations, preferably a suitable system of selective ringing should be em loyed, such for example, as that disclose in Patent #779,533 granted Januar 10, 1905, wherein the bells of the subscri rs are caused to respond to currents of different frequencies obtained from ringing generators'at the central office. In the resent instance I have diagrammatically i lustrated a party line key in addition to the rin ing-key 24-26 which includes the keys '-KKK associated with corresponding generators G"'G'G. With this arrangement, the depression of any given key will supply current to the key 24-26 from the corresponding generator and the corresponding substation call si al attuned to this generator will respon Upon the depression of any given party line key and the simultaneous depression of key lovers 24-2G, tho

tact 11 of cut-ofl' relay 12 to ground.

corresponding gcnt-u'ator will lut-runicctt-d to the tip side of the circuit. and ringinp current will thus be applied until the key levers 24-26 are released. In the present. instance, locking mechanism for the party line kc s is diagrammatically illustrated by the sliding plate 44 adapted to move toward and from the keys K'K-KK through the cooperation of springs 45 and the guiding pins 46. The projections on the plate 42 adjacent to the lovers K-K K'--K are inclined and shouldered so that upon the depression of any key, the sliding plate is forced against the pressure of the springs 45 out of engagement with the other keys. and any previously depressed key is thereby allowed to return to normal under its own spring tension, while the key last to be depressed is retained in its depressed position.

\Vith this preliminary description of the apparatus employed, it will be apparent that in operation, assuming that a party at A on line L desires to converse with a party at say, substation 13' on line If, upon the removal of his receiver 4 from itsswitchhook 5, a ath for current will be completed through e ectromagnet 6 at substation A which may be traced from the live pole of the battery section b through the winding of line relay 14, closed contact 13 of cut-oil relay 12, line limb 2, alternate contact 47 of electronuignct 6, closed contact 48.01" switch-hook 5, line limb 1 andcloscd con- At this point it may be noted that upon the removal of the receiver 4 from its switch hook 5, contact 48 is closed and by reason of the enga ement of the insulating projection 49 wit contact 47, said contact. 47 is carried to its alternate position. In this movement the alternate contact is closed, preferably after contact 48, and justv before the switch-hook reaches its final position. Before this final position is reached, the insulating projection 49 slips by the yielding end of contact 47 and said contact is free to return under its normal tension to its normal position as soon as electronnignet 6 is detinergized. From this it will be seen that the closing of the circuit just outlined energizes electromagnet 6 and thereby holds contact 47 in its alternate position. The. closing of this circuit also energizes line rclay'14 which in turn closes its contact. to light line lamp 50 as an indication to the o erator that connection with another subscribers line is desired. It will be noted that at this time current flows through the electroinagnet (3, as well as lino relay ll.

from the live. or negative, pole. of the battery section 1). Upon observing the display of the call signal 50, the operator will in sort uuswerin plug i" into an answering jack. such as S. of the line 1/. lll|l't'l) mo lnentarily supplying current from the sanitlllt) pole of the battery section I) through ping and jack sleeve contacts to the line limb 2 t to the ulcctroluagnet and the electromagiu-t (3 at the calling sub-- station. and at the same time closing a cir cnit through the cutoff relay 12 of the line L. The former circuit extends from the live. or negative. pole of the battery section Zr through th winding of relay 33. closed 'tflitucls' fit fifl of supervisory relay 31. strand 1'' ja lt contact 53. line limb 2. alt rnate ontact 4i. winding of electromaguet (5. wios-tl contact is. liuc limb 1. jack (Ullllltl strand 13 repeating coil winding in to the opposite or grounded pole of the battery section I). At the same time this current is established. a circuit including the cut-off relay winding is completed from the live. or positive. pole of the battery section through strand 1? including resistance 20. supervisory lamp Q9. thence by jacket contact 55 and winding o'l cutoli' relay 12 to ground. The cnergization of the cut-otl relay destroys the normal line limb connections with the battery sec tion 7). but. as noted. th se are replaced by other similar counectioi'is through the plug and jack contacts. These latter circuit. connections of the battery section 7) with the line limbs are. however. of short duration. The inclu ion of the relay 33 in the newly established circuit immediatcly causes its energization and the subsequent closing of its contact 56. The closing of this contact completes a momentary local circuit extending from the ive. or negative. pole ol the battery section I) through the winding of relay 33. closed contacts I'll--52. closed contact 56. the winding of supervisory relay 31 in parallel with the non-inductive resistance 57-. the repeating coil winding if to the live, or positive. pole of the battery section If. The closing of this circuit encrgizes supervisory relay 31. which thereupon closes contact 59 and contacts B l-58 and subsequently opens contacts 5l-ii2. The closing oi contact 59 closes a shunt. including resistance (30. about the lamp 2! and thereby prevents its display as a signal. The opening of contacts 511-52 and the previous closing of contacts interrupts connection between the live. or negative. pole of the battery section 7: and the strand 16 and completes a connection from the live. or positive. pole of the battery section 71 through repeating coil winding it). resistance 57 in parallel with winding of relay 31, and closed contacts 5258 to strand 16. This change, it will be observed. changes the polarity of the battery connected to said strand and thus supplies current. to the electromagnet 6 of the calling substation A in a direction opposite to that previously supplied from battery section 7/.

Due td the momentary local circuit including both battery sections bb'- and the following application of reversed current said magnet is deenergized and its contact 47 thereupon returns to its normal position. In order that the contact, 47 may return to its normal position upon a reversal of current llow through electromagnet (3. said magnet is so constrin-ted. and its contacts are so adjusted. that the contact 47 will disengage its alter nate contact at the very beginning of its return movement. This return of the contact 4T interrupts the previous path through the elcctromagnct ti and replaces it by a path through transmitter 3. control-key l. switch-hook :3 and primary winding of induction coil 9, thus establishing a talking circuit through substation A which had not hitherto existed. The operator will now depress hcr listeningdrey levers -l1-l'3 and thereby connect her telephone set S in circuit. the receiver 39. winding of induction coil 3% and condenser 40 being coni'iected in bridge of the strands 21-22. \Yhen so connected she is able to converse with the calling part and upon learning that substiv tion it is to be signaled. she will then test line L to determine its busy or idle condition. This she does in the usual way by touching the tip of the calling plug 1 to the contact 55 of one of the. multiple jacks .l associated with said line; and in case said line is in use. a potential above that of ground will exist at the contact thus touched. and current will flow therefrom over strand 21 through the repeating coil winding 2.) to ground. Since at. this time the listening-keys l142 are depressed. the condenser 40 will be momentarily charged and discharged and the usual click in the operatcns receiver 39 resulting therefrom will serve as an indiuition to her that the line is busy. The potential of the contact In") of the tested. jaclv' will be obtained through the connection of a multiple ot.

the jack te ted with the sleeve strand of another linlt'circuit connected to said line. This connection may be either through the sleeve contact of an answering plug corresponding to plug 1 and the associated strand corrcspout'ling to strand 23. or through the sleeve contact of a calling plug corresponding to plug l" and the associated strand corresponding to strand 1?. if tlrc line found to be busy. the operator will so inform the calling party. If. on the other hand. the said line is found to be idle. the operator will insert the calling plug into the tested jack and thereby complete a circuit through supervisory lamp 3t) and cut-off relay 12 of the line If over the strand 23 in a manner similar to that previously described in connection with line L. thereby causing the display of the supci isory lamp and the actuation of the cut-oti' relay. The action of the lattcr,- as before, will be to as the same is depressed, a circuit is completed from the live pole of the generator 1 through closed key K, closed key lever 24, strand 21, jack contact 54, line limb 1, the call-bell 8 and condenser 7 at each of the substations, line limb 2, jack contact 53, strand 22 and closed key lever726 to ground. Thus ringing current is applied which causes the actuation of the call-bell 8 at sub-station B as a signal to the called-for party, as previously pointed out.

As soon as the key K is depressed, its engagement with the adjacent inclined face of the plate a; forces said plate away from the remaining key levers far enough to allow any one of them which is retained to return to normal position under its inherent tension. By this means an o rotor may readily determine what particu ar party was last signaled since the actuated key remains down until a second key is operated. Thus itwill be apparent that upon the depression of any other key, such as K the sliding plate 44 will be moved out of engagement with key K, and it will be allowed to return to its-normal position. As soon as the called-for party responds to the call by the removal of his receiver, the ringing-key levers 24-26 having been released, contacts 47 and 48 at his substation will be actuated, the former being moved to its alternate position and the latter being closed. This movement. of the contacts 47-48 at once completes a path for current from the active, or negative, pole of the battery section Z1 through the winding of relay 34, closed contacts 6i62. strand 22, jack contact 53, line limb *2, alternate contact 47, winding of electromagnet 3, closed contact 48, line limb 1, jack contact 54, strand 21 and repeating coil winding 25 to the grounded positive pole of battery I). The closing of this circuit will energize electromagnet 6 sufficiently to cause it to hold its contact 47 in its alter nate position. The existence of this circuit howeven will be only momentary. As soon as it is completed. relay 34 will close its contact 63 and thereby close a local circuit from the active, or negative, pole of the battery section 6' through the winding of relay 34,

. contacts 6162, closed contact 63, winding of supervisory relay 32 and non-inductive resistance 64 in parallel, repeating c011 winding 27 to the active, or positive, pole of the battery section 5 thereby energizing supervisory relay as previously explained in connection with supervisory relay 31 to close the shunt about its lamp 30 and to reverse the polarity of the battery connection to the "strand 22. This reversal as before, causes the deenergization of the previously energized electromagnet 6 at substation B with a consequent return of its contact 47 to its normal position to complete the previously interrupted circuit through the transmitter 3 and control-key 10. As soon as this takes place, conversation may be carried on between substations A and B, and while the receivers at these substations remain ofi their hooks, the associated supervisory lamps 29 30 will remain dark, but as soon as either receiver is hung upon its hook, all possible paths for battery current between the line limbs at thecorresponding substations will be broken and the associated supervisory lamp will be lighted by reason of the deener izatign of its supervisory relay. The lighting of both lamps will constitute a signal to the operator to take down the connection. If at any time during the existence of this connection, any party on the line L desires to make a call or to listen to the conversation carried on between substations A and B, he will be unable to do so. This is true for the reason that after removin his receiver from its hook so as to establish a path for current through his electromagnet 6, he will be unabie to obtain a reversal of current to release the contact 47 of said clectromagnet to establish the conversational circuit through his substation. In this connection, it will be noticed that when contact 47 is in its alternate position, there will be no path for current through the primary winding of the associated induction coil 9, even though the receiver be off its hook. Furthermore the removal of the interfering partys receiver from its, hook will not occasion the display of the associated line signal 50 since the normal connection of the relay 14 with the line is interrupted.- It will be obvious from the above that if a party on line L desires to listen to the conversation or to signal the operator, he will be unable to do so for the same reasons.

If in the first instance the party at substation A desires to converse with another party on the same line, as, for example, a party at substation A, he will call in the manner heretofore described and have his conversational circuit established by the operation of the reversing mechanism at the central office. The operator will then, upon learning that conversation is desired with a party at substation A. remove the plug P from the jack of the line and replace it by plug P and depress ringing-key levers 24 26 and the appropriate party line key K,

K", K, or K, to cause the actuation of the tact. .This 'line construction is well call-bell 8 at substation A. Since the current reversing mechanism associated with link-circuit L is actuated as soon as a bridge for battery current is completed between the limbs of a connected line, it is necessary that the calling party, at substation A interrupt the path for battery current which has been completed through his. transmitter 3 before the subscriber at A raises his receiver. This he does by depressing his control-key 10. In this way, he leaves the substation equipment at substation A free to cause the actuation of .the reversing: mechanism upon the release of the ringing-key levers. 24-26 in the same manner as though the substation A were on another line. As soon as the calling party hears the party at A respond,

he will restore his key 10 to its normal position and thus a conversational circuit will be established between substations A and A. During the existence of this connection,

transmission current will be supplied to the two sides of the line from the battery section 6 through repeating coil winding 27 and strand 22 on the one hand, and repeating coil winding 25and strand 21 on the other. During conversatiom'the shunt about the supervisory lamp 30 will be maintained closed and this shunt will not be removed until both parties have restored their receivers and thereby interrupted all previou sly existing paths for current between the line limbs. \Vhen this is done, the lamp 30 will be displayed as a signal to the operator to take down the connection.

Referring now'to that form of the invention illustrated in Fig. 2, it will be seen that the line limbs of the lines If-L are provided at the central office with the same relays and connections as illustrated in Fig. 1, except that each of the jacks is provided with two contacts, one bemgdesigned for connection to the line limb 2, and the other for connection to the line limb 1 upon the actuation of the cut-off rela which is permanently connected to the utter jack conknown. In the present instancev-also, the line L is provided with four substations designated C, C, C, C, while the line L is provided with two substations D, 1). Each of the substation equipments comprises a transmitter 3', receiver 4, switch-hook 5f, electromagnet 6, condenser 7', call-bell 8, induction coil 9', and control-key 10', connected somewhat similarly to the corresponding parts at thesubstations of Fig. 1. In the resent instance, however, the removal oi the receiver 4' from its hook 5' causes a movement of contact 100 to its alternate position and the closure of contact 101. As in the'previous case, the contact 100' is actuated b an insulating projection 102 extending rom theswitch-hook 5 and adapted to slip by the end of said contact just prior to the switch-hook reaching the limit of its closing movement. At the central oflice, the interconnecting link: circuit L is of the well known Kellogg four- 'relay type, modified in accordance with the present invention. In this link-circuit, a pair of relays 103-104 is associated with the answering plug P; and a corresponding pair of relays 105-100 is associated with the calling and of the link-circuit and the calling plug P*. The link-circuit L is of the two-wire type and the strands 107-108, united by the interposed condenser 109, unite the tip contacts of the plugs P and P; while the strands 110 111, united by the interposed condenser 112, connect the sleeve contacts of said plugs. The relays 103-104 jointly control the supervisory lamp 113 through the agency of their contacts 114115 respectively, while relays 105-106 control supervisory lamp 116 through the agency of their contacts 117118 respectively. Relays 103, 105 and 106 are rovided with additional contacts whose unctions will be described presently. One of these contacts 119,

while in its normal position, maintains a connection from the strand 108 throu h one winding of the induction coil 120 of t e operators telephone set S. This connection is instrumental in making a test of a calledfor line, as will he more fully explained hereinafter. The operators telephone set includes the transmitter 121, in a local circuit with a second winding of the induction coil 120-and a local battery 122,-and the head receiver 123 adapted to be included in bridge of the link circuit strands 108-111 with another winding of the induction coil 120 and the condenser 124. The operators set is thus included on the depression of the keylevers 125-126. For the purpose of supplying ringing-current to the line, an auto matically retained key is is provided in conjunction with four ringing-keys In, 10 is, each associated with a corresponding interrupter z" '5 i i, and ringing generator 9', y g, g. The number of these party keys and interrupters and generators is dependent upon the number of parties on the lines with which the particular link-circuit is adapted to be used and may be varied as required. Any preferred method of selectively ringing stations on the line may be employed, and as before, I have chosen the harmonic method in which generators, such as g, 9 g and g, are designed to supply currents of difl'erent frequencies and .the substation call devices are correspondingly tuned so as to correspond therewith, as clearly indicated in the aforesaid patent. Thus when current is supplied from any articular generator, it will biz-instrumental 1I1 ringing the call-bell at one of the substations on the line only, and the same will be true for each of the other generators. Upon the depression of any one key, k, 70 k is, at the time the key is is depressed, the corresponding generator is connected to the tip side of the circuit alternately with battery. This is brought about by the action of the associated interrupter. Upon the depression of the key is, its contacts 127-128 are moved to their alternate positions and are adapted to be retained in such positions by the catch 12$) controlled by the electromagnet 130 in a manner to be hereinafter more fully explained. The link-circuit is also provided with a control rela 131 which is included in circuit between t e live pole of the battery 5 and a contact of relay 106. The party line keys 7:, 10 k and In are provided, as before, with a sliding catch plate 132 which operates, as before, in retaining and releasing said keys.

With this preliminary description of the apparatus employed, it will be apparent that in operation-assuming that a party at substation C for example", desires to converse with a party at substation D the removal of the receiver 4' from its hook 5 at substation C will move contact 100 to its alternate position and close contact 101 so as to complete a bridge for battery current/between the line limbs l and 2 at said substation. As soon as this is done, a path for current will extend from the live pole of the battery b through the winding of line relay 14, normal contact 13 of cut-ofi relay 12, line limb 2, winding of electromagnet 6, alternate contact 100, closed contact 101, line limb 1, and normal contact 11 of cutofi' relay 12 to ground. The closing of this circuit will energize electromagnet 6 so as to hold its contact 100 in its alternate position, notwithstanding the projection 102 of the switch-hook 5 has by this time slipped past the projection on contact 100 and therefore exerts no force to hold said contact in its alternate position. The closing of the circuit will also energize line relay 14 to cause the closin of its contact and the subsequent display 0 the line signal lamp 50. At this time, no conversational circuit will exist at the substation, but the transmitter circuit will be interrupted at normal contact 100. Upon observing the display of the call signal 50, the operator will insert the answering plug P into an answering jack, as P, of the line L. This will result.in closing a circuit throu h relays 104 and 12, which may be traced rom the live pole of battery 2), through the winding of relay 104, strand 110, plug and jack sleeve contacts and winding of cut-oil relay 12 to ground. By the consequent energization of cut-01f relay 12, the normal connection of line limbs is broken and said limbs are extendedto the jack contacts. As soon as the cut-01f relay contacts are actuated, relay 133 is energized, and

through its cooperation with relay 103, the connection of the battery b to the line is reversed. Thus upon the actuation of cutoff relay 12, a path for current extends from the live pole of the battery 6 through the winding of relay 133, contacts 134-l35 of supervisory relay 103, strand 107, plug and jack tip contacts, line limb 2, through electromagnet 6 at substation (1*, line limb 1 to ground through the cut-off relay. This supplies current to the electromagnet 6 in the same direction as before and maintains said magnet energizerh Immediately, however, contact 136 of relay 133 is closed and the opposite pole-namely, the grounded poleis connected to the tip side of the circuit, thereby reversing the direction of current supplied to electromagnet 6' and thus causing its deenergization, with the resultant closing'of the transmitter circuit at said substation. As soon as contact 136 is closed, current will be supplied to supervisory relay 103 over a path including the winding of relay 133, contacts 134-135, closed contact 136 and winding of rela 103 to ground. The completion of this circuit will at once break the contact 114, thus interrupting the circuit of the supervisory lamp 113, and will close contacts 137-135 and subsequently open contacts 134-135. As soon as contacts 134-435 are separated, relay 133 will be denergized, but relay 103 Wlll be continued energized by reason of the usual return over the tip side of the circuit. The complete circuit resulting at this time may be traced from the live pole of the battery 5, through the Winding of supervisory relay 104:, plug and jack sleeve contacts, to the cut-ofi' relay, thence by one path through the winding of said relay to ground, an by another path over the line limb 1, through substation C over line limb 2, plug and jack tip contacts, closed contacts 135*-137 and winding of relay 103 to ground. The direction of current flow over this circuit is also. in the opposite direction to that initially established through the winding of electromagnet 6. The operator will now depress her listening-key levers 125-126, thereby including her telephone set S in circuit. Upon learning from the calling party that connection is desired with substation D she Will then test the line L to determine its busy or idle condition. This she does by touching the tip of the calling plug P to the sleeve contact of one of the multiple jacks associated with said line; and in case said line is in use, a potential above that of ground will exist at the contact thus touched, and current will flow therefrom over strand 108. closed contact 138'139 of supervisory relay 105, normal contact 119 of supervisory relay 106, and a winding of induction coil 120 to ground, thereby producing the usual click in the operators receiver 123 as an indication to her-that the line is busy.

e potential at the sleeve contact of the tested jack will be obtained through the connection of a multiple of the jack tested with the sleeve strand of another link-circuit connected to theline. This connection may be either through the sleeve contact of a calling plug corresponding to plug P and the associated supervisory relay corresponding torelay 106, or through the sleeve contact of the plug corresponding to P, and through the resistance corresponding to resistance 140, or through the sleeve contact of an answering plug corresponding to answering plug P and the winding of the associate supervisory relay corresponding to relay 104. If the line L is found to be busy, the o rator will so inform the callin party. I on the other hand,said line is ound to 'be idle, the operator will insert the calling plug P into a jack of the tested line and thereby complete a circuit through the supervisory relay 106 and cut-ofi relay 12 over the sleeve side of the circuit in a manner similar tothat previously described in connection with line L, thereby closing contact 118 of supervisory relay 106 and moving its contact 119 to its alternate position; and by the action of the cut-off rela 12, destroying the normal connection of t e line limb L with the battery b and the line relay 14. The closing of contact 118 will cause the display of supervisory lamp 116, while the movement of contact 119 to its alternate position will supply a connection between the live pole of the batter b and strand 108, which may be traced rom the live ole of said battery through the winding 0 relay 131, alternate contact 119 and contacts 139138. The next act on the part of the operator in compileting a connection will be to depress her e k and then depress a party line key, suc as in, corresponding to the station of the party wanted. As soon as key 11: is depressed, contact 127 is engaged by catch 129 and the key is held -in its depressed position. In this position, the previously traced circuit through the supervisory relay 106 is interrupted at normal contact 128, but current is supplied to the cut-01f relay via resistance 140 and alternate contact 128. At the same time, strand 108 is interrupted at normal contact 127 and the battery aiul generatorconnection through the winding of relay 130 is established with the tip of the plug P. The depression of the key k also causes its engagement by the catch-bar 132 and it is retained in this depressed position thereby. While keys 1: and k remain thus depressed, current will flow from the live 'ole of the generator 91 through interrupter a, key is, winding of relay 130, which is unresponsive to the enerator current, alternate contact 127 ug and jack tip contacts, line limb 2, the substation condensers 7' and call-bells 8, line limb 1 and cut-oil relay 12 to ground. By reason of the frequency of the current thus supplied, the callbell 8' at the substation at only is actuated as a signal to the party at such substation. As soon as he responds to the call, the removal of his receiver from its hook will close contact 101 and move contact 100 to its alternate position, thereby establishing a path for the flow of battery current between the linelimbs 1 and 2. With this path through the substation, current will be supplied from the battery b to cause the actuation of electromagnet 130 with the consequent release of the key is.

The circuit for the retaining magnet 130 may be traced from the live pole of battery I), through the interrupter '5 key 7c, winding of relay 130, alternate contact 127, plug and jack tip contacts, line limb 2, through the substation bridge, line limb 1, and the winding o'f'cut-ofl' relay 12 to ground. Upon the return of the key is to normal, supervisory relay 106 is again energized and current at once flows from battery through the winding of relay 131, alternate contact 119 of relay 106, closed contacts 139-138, linkcircuit strand 108, plu and jack tip contacts, line limb 2 through the substation, line limb 1 and winding of cut-off relay -12 to ground. This circuit, which exists momentarily, supplies current to the electromagnct ft in the some direction as that supplied through the winding of electromagnet 130. Consequently the electromagnet 0 at substation I) maintains its contact 100 in its alternate position. The resulting energization of relay 131, however, innnediately closes contact 141 to thereby establish a new path for current which may be traced from the live pole of the battery I), through the winding of relay 131, alternate contact 119, closed contacts 130-138. closed contact 141 and winding of relay 105 to ground. The closing of this circuit immediately energizes relay 105 suflicicntly to close its contacts 142-138 and subsequently to open contacts 138-139. The opening of the latter contacts interrupts the connection from the live pole of the battery 6 to the strand 108, and the closing of contacts 138-142 completes a path in bridge of contact. 141 of relay 131 and thereby maintains the opposite pole of the battery I) in connection with strand 108. By reason of this reversal of battery connections, the current through the electromagnet 6' at substation D is reversed and the contact 100 of said electromagnet returns to its normal position, thereby completing a conversational circuit at said substation. At this time, current is supplied for transmission to the sleeve side of the line through supervisory relay 106 and to the tip side of the line through supervisory relay 105.

Upon the energization of relay 105, supervisory lamp 116 has its circuit, interrupted at contact 117. \Vith the parts in this condition, conversation may be carried on between substations and D At the end of conversation, the restm-ation of the receiver at either of these substations to its book breaks the existing path for battery current through the corresponding substation and causes the deenergization of the corresponding tip supervisory relay, with a consequent lighting of the corresponding lamp. The lighting of both lamps 113116 constitutes a signal to the operator to take down the connection. If at any time during this con nection, another party on the line L desires to make a call or to listen to the conversalion carried on between the connected sub stations, he will be unable to do so. This is true for the reason that upon removing his receiver from its hook, he will close his contact- 101 and move his contact 100 to its alternate position and thereby complete a path for current through his electromagnet t3; and since the reversing relay mechanism at-the central office has already operated, he will be unable to obtain a reversal of current flow through his electromagnet 6' to cause the restoration of his contact 100 to its normal position. \Vithout this restoration, there will be no circuit through his transmitter 3 or the primary of his induction coil 9. This action of the interfering party will not cause the operation of the associated line relay 14 or the display of its lamp 50, since the normal connection of the line relay to the line L has been interrupted by the revious operation of the associated cut-o relay. Obviously, a party at a substation on the line L will be unable to interfere or signal the operator for like reasons.

Now if, instead of the subscriber at substation C" desiring to converse with a party on another line, such as at substation D on line L as heretofore described, he desires to converse with another party on his own line, such as a party at substation C, he will call in & ."*l!1tlI1I1BI heretofore describedand the operator, upon learning that the substation with which connection is desired is on the same line as the callingparty, will remove the plug P from the ack of the line L and insert in its stead plug P. The operator will then depress her ringing key I: and the proper party line ringing key k, 10 k or la and signal the called party in the usual Way. Since the existence of a path for battery current between the line limbs 1 and 2 at any point on the line will be instrumental in causing the operation of the magnet 130, releasing the key A at the central ofiice, thusdisconnecting the ringing generator from the line, it is necessary that the subscriber at the calling stationnam'ely, C interrupt the existing path for battery current throu h his substation prior to the depression of icy k. This is also necessary prior to the response of the called party in order that the removal of the receiver from the switch-hook of the called party will set the reversin relay mechanism in operation to reverse t e current flow over the line and thereb close the conversational circuit at the ca led-for partys substation. This interruption of the path for battery current at the calling partys substation is brought about by the pressing of key 10' so as to interrupt. the existing path through closed contact 101, normal contact 100, transmitter 3', switchhook 5', winding of induction coil 9' and key 10'. As soon as the calling party hears the response of the called party, he may restore his key. 10' to normal and from that time on will be able to converse with the desired part During this conversation, current will e supplied to the substations, as before, through the winding of supervisory relay 106 to the sleeve side oi the circuit, and through the winding of supervisory relay 105 to the tip side of the circuit. At the end of conversation, with the parties thus connected, it will be necessary for both receivers to be restored to their switch-hooks in order to cause the display of the associated supervisory lamp 116. In the case of a connection of this sort, the display of this lamp will serve'as a signal to the operator to take down the connection.

In Fig. 3 of the accompanying drawing, I have illustrated a still further modification of substation circuits which may be employed in the systems of either of the preceding figures. In this instance, the transmitter 3", receiver 4", switch-hook 5", electromagnet 6", condenser 7", call-bell 8", induction coil 9" and control-key 10" aresubstantially the same as those heretofore described, but are differently connected. By the arrangement. of this figure, a conversational circuit is com leted through the substation, as a result oi the reversal of current supplied to the electromagnet 6", whenever .a call is transmitted from said substation or a call is transmitted to it from a substation on some other line; but whenever a call is transmitted to it for the purpose of establishing a conversational circuit between it and another substation on the same hne, the

conversational circuit through the called substation is completed by shunting current from the called substation electromagnet 6". In other words, it is possible to permit a second subscriber to be connected with the same line by shunting current from the electroinagnet of said line so that it will restore its contacts to thereby establish the necessary conversational circuit. In the operation of this modified circuit arrangement,

the removal of the receiver for the purpose of initiatin" a call completes a circuit from the line lim x 1 to the line limb which may rent reversing mechanism at the central be ll'llt ttl through transmitter 3", switchhook 5". electromaguet ('i" and alternate eontur-t. .200, said contact 200 being thrown to its alternate position upon the closing movenn-nl of the switch-hook 5 in a manner similar to that heretofore described in connection with the switch-hooks 5 and 5'. When the ONE-Putt)! answers, the current reversing mee ianism ofeithcr of the cord-cireuits will cause a reversal of current ilow through the electromugnet G" and the transmitter circuit will be com letcd from the line limb 1. through transmitter 3", switchllnuk a", winding of induction coil 9" and normal contact 200 to line limb 2.. In case the subst at ion is called, ringing current will tlow through the condenser 7' and call-bell S" as before.

It the. subscriber at the substation is called for the purpose of conversing with a subscriber at a substation on another line, the response 'of the party in removing his rearrive! from its hook will close the path for battery rullent through the electromagnet a", previously traced, and this will at once be instrumental in actuating the current reversing mechanism at the central oflice, as before, to reverse the current flow throu h the. electroma et 6" andthereb cause t to completion 0 the conversationa circuit at said substation. In case a calling party with this substation equipment desires to converse with anothertparty on his own line, he calls in the usual way and obtains a suitable conversational circuit in the manner heretofore pointed out. In making the connection, the operator as before inserts the calling plug into the jack of the line and ringsthe called-for party in the usual way. Since there is a path for battery current through the transmitterBf, switch-hook 5" winding of induction coil 9" and normai contact 200 at the substation of the calling party, it will be necessary, where the link circuit L, of Fig. 2, is used, that the operator hold down the key 70, since otherwise the associated retaining m Ignet 130 would be ener ized and the key would be released. When t e called party responds by removing his receiver electroma et 6" and transmatter a" will be include in bridge of the line limbs, but there will be no circuit from the receiver 4". This will be true since the movement of the switch-hook moves the contact 200 to its alternate position and current will flow through the electromagnet 6 to maintain said contact in said position. As soon as the called-for party responds, the calling party will deiinergize the called partys electromngnetti" by depressing his ey 10" to shunt current from said electromagnet and thereby permit its contact 200 to retract and thus complete the conversationai circuit at that substation. In this connection.- it should be noted that the curoilice cannot be utilized to restore the contact of thy called party by reversing the direction of current flow through the associated eltctronn'ignet (5", since said re versing'mechanism is operated as soon as the linlr-circudis connected to the line, provided a bridge for battery current exists between the line limbs. This does exist in the case of the callingline and consequently it this reversing mechanism were relied upon, it would operate before the called party had removed his receiver. In the present case, supervision is obtained as heretofore explained.

t will be apparent from the above (118- closurc that my invention is capable of use in systems of various sorts. It will also be apparent to those skilled in the art that many alterations and modifications may be made in the circuit arrangements and in the apparatus diagrammatically illustrated, without departing from the spirit and scope of my invention. I therefore do not wish to be limited to the specific matter illustrated, but aim to cover by the terms of the appended claims, the invention in its various uses and in its various modified forms.

What I claim as new and desire to secure by Letters Patent of the United States is 1. A party line telephone system comprisin a telephone line terminating at a centre oilice, a plurality of substations on said line, a signal associated with said line at the central oilice, means under the control 'of each subscriber for actuating said signalwithout closing a conversational circuit at his substation and an electroma met at the exchan e automatically actuate on connection ma e with the line to cause the closure of said conversational circuit.

2. A arty line telephone system comprisirtilg a te e hone line terminating at a central 0 co, a p urality of substations on said line, a transmitter,receiver and switch-hook at each substation, circuit connections at each substation whereby the removal of the receiver from its book normally closes a signaling circuitwithout connecting the transmitter and receiver for conversation, a sigml. at the central oflice.responsive to the closing of said. signaling circuit, and an electromagnet at the exchan e automatically actuated on connection am e with the line to cause the closure of said conversational circuit.

3. A part line telephone system comprising a telep one'line terminating at a central otlice, a plurality of substations on said line, a transmitter, receiver and switch-hook at each substation, circuit connections at each substation whereb the removal of the receiver from its hoo normally closes a of each subscriber for actuating said signal without closing a conversational circuit at his substation, means for subsequently closing said conversational circuit at the said substation, and means subsequentl under the control of thesubscriber at sai substation to permit the closing of a like conversational circuit at another substation on said 5. A arty line telephone system comprisa all; hone line terminating at a central '0 ce,.a p urality of substations on said line, each having a transmitter, receiver andv switch-hook, circuit connections at each substation whereby the -removal of the receiver from its book normally closesa signaling circuit without connecting the transmitter and receiver for conversation, a signal at the central ofiice responsive to the closing of said signaling circuit'at any particular substation, means for subsequently connecting the transmitter andreceiver at said substation for conversation, and means subsequently under the control of the subscriber at sai substation to permit the connection of the transmitter and receiver at another substation on said line for conversation.

6. A party line telephone system compris-l inflg a tele hone line terminating at a central 0 cc, a p urality of substations on said line, each having a transmitter, receiver and switch-hook, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a si naling circuit without closing a circuit t rough said transmitter, a signal at the central office responsive to the closin of said signalin circuit at any particu ar substation, means for subsequently closing the circuit through the transmitter at the substation, and means subsequently under the control of the subscriber at said substation to permit the closin of a like circuit through the {ransmitter 0 another substation on said 7. A party line telephone system comprising a telephone line terminating at a central ofiice, a plurality of substations on said line, a signal associated with said line at the central ofiice, a controlling electromagnet at each substation, means under the control of each subscriber for actuating said signal and forsupplying current to his electromagnet,

a pole changing relay at the exchange controlled responsive to the line connections at a substation to modify the current supplied to said electromagnet and means responsive to such modification to alter the circuit connections at the acting subscribers substation.

8. A arty line telephone system comprisixiifiga te ephone line terminating at a central o co, a plurality of substations on said line, a signal associated with said line at the central ofiice, a controlling electromagnct at each substation, means under the control of each subscriber for actuating said signal and for supplying current to his electromagnet, a pole changin relay at the exchange controlled responsive to the line connections at a substation to modify the current supplied to said electromagnet and means responsive to such modification to close aconversational circuit at the apting subscribers substation.

9. A party line telephone system comprising a telephone line terminating at a central office, a transmitter, receiver, switch-hook and controlling electromagnet at each substation, circuit connections ateach substation whereby the removal of the receiver from its hook normally closes a circuit through the associated electromagnet, a signal at the central oflice responsive to the closing of said circuit, a pole changing relay at the ex change controlled responsive to the line connections at 'a substation to modify the current supplied to said electromagnet and means responsive to such modification to alter the circuit connections at the acting subscribers substation.

10. A party line telephone system comprisin a telephone line terminating at a centra ofiice, a transmitter, receiver, switchhook and controlling electromagnet at each substation, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit through the associated electromagnet, a signal at the central office responsive to the ,closing of said circuit, a pole changing relay at the exchange controlled responsive to the line connections at a substation to modify the current supplied to said electromagnet, and means responsive to such modification to connect the transmitter and receiver at the acting subscribers substation for conversation.

11. A, party line telephone system comprising a telephone line terminating at a central office, a plurality of substations on said line, a signal associated with said line at the central ofiice, a controlling electromagnet at each substation, means under the control of each subscriber for actuating said signal and for supplying a unidirectional current to his electromagnet, means for reversin the direction of current supplied to said re lectromagnet, and means responsive lo'such reversal toalter the circuit wnneclions at the acting suhscribers substation.

12. A party 'line telephone system comprising a telephone line terminating at a. central otiice, a plurality of substations on said line, a si al 'tlSSOOlflltfl withi-iairl'line at the centre 'ollive, a controlling electromagnet at each substation, means under the control of each subscriber for actuating said signal and for supplying a uni-directional current to his eli-rtroniagmct, means for rcversinlg the direction of current supplied to said e ectromagnct. and means responsive to such .revc'rsal tot-lose a conversational circuit at the acting subscrihci"s substation.

13. A party line telephone system comprisin" a telephone line terminating at. a central oilicc, a transmitter, receiver, switchhook and controlling elect romugnet at each substation, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit through the associated elect-romagnet, a sigml at the central oflioe responsive to the closin of saidcircuit, means for roversin the direction of current supplied to sai clectromagnct, and means responsive to such reversal to alter the circuit connections at the acting subscribers substation.

14. A party line telephone system 'cmnprism a telephone line terminating at a contra oliice, a transmitter, receiver, switch hook and controlling electromagnet at each substation, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit through the associated eloctromagnet, a signal at the central oflicc responsive to the closing of said circuit, means for reversing the direction of current supplied to said electromagnct, and means responsive to such reversal to connect the transmitter and recciver at the acting subscribers station for conversation.

15.A party line telephone system comprisin a telephone line terminating at a contra office, a plurality of substations on said line, telephone equipment at each substation responsive only to a reversal of battery current fio'w over the line to complete a conversational circuit at said substation, a battery, and means for causin a reversal of battery connections.to the me to complete thereby a conversational circuit at a subscribers substation. 1 I

16. A party line telcphone'syatem comprisin a telephone line terminating at a centra office, a plurality of substations on. said line, telephone equipment at each substation responsive only to a definite modification of the battery current'flow over the line to complete a conversational circuit at said substation, a battery, a pole changing relay at the exchange for operation'mponsive to the condition of said telephone cquipmcnt for'causing the said modification cl battery current to complete thereby a conversational circuit at said subscrilwrs station.

17. A party line telephone system (oniprising a telephone line tern'iinating a1 a central oilice, a pluralitv of substations on said line, a signal assoriatcd with said i u-- at the ccntralfotlicc, a (ollll'ulliug elm-m. magnetat each of said substations, llil'ollr under the control of each subscriber for or touting said signal and for supplying a currentto his said clcctroma net, means for modifying the current supp ied to said elm 'tromagnct. means responsive to such modification to complete a conversational cir uit at said substation, and means for controlling the modification of current supplied to a second elcctromagnet on said line whereby the closing of a second conversational circuit. at a second substation on the line is accomplished.

18. A party line telephone system comprising a telephone line terminating at a central ofiice, a plurality, of substations on said line, each having a transmitter, receiver, switch-hook and controlling clect-romagnet, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit'through the clec tromagnet, a signal at the central oflice rcsponsive to the closing or said circuit at any particular substation, means for modifying the current so licd'to said electromaguct. means responsive to such modification to connect the transmitter and receiver for conversation, and means for controlling the modification of current supplied to a second electroma let on said line whereby the connection o the transmitter and receiver of a second substation on the line for conversation is accomplished.

1!). A party line telephone system comprisin a. telephone line terminating at a contra oflice, a. plurality of substations on said line, a si al associated with said line at the contra oifice, a controlling electroma net at each of said substations means an or the control of each subscriber for actuating said signal and for supplying a uni-directional current to his said electromagnet, means for rcversin the direction of current supplied to sai electromagnet, means responsive to such reversal to complete a conversational circuit at said substation, and means for controlling the reversal of current supplied to a second electromag'neton said line whereby the closing of a second conversational circuit at a second substation on the line is accomplished.

20. A'party line telephone system coln prisi 'a tale hone lino terminating at a central o cc, 0. p urality of substantions on said line, each having a transmitter, receiver.

switch-hook and controlling elcctromagnet,

circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit through the electromag'net, a signal at the central ofiicc responsive to the closing of said circuit at any particular substation, means for reversin the direction of current supplied to sai electromagnet, means responsive to such reversal to connect the transmitter and receiver for conversation, and "means for controllin the reversal of current supplied to a second electroma et on said line whereby the connection o the transmitter and receiver of a second substation on the 'line for conversation is accomplished.

21. A party line telephone system coinprisin a telephone line terminating at a centra oflice, a pluralityof substations on said line, a signal associated with said line at the central ofiice, a controlling electromagnet at each substation, means under the control of each subscriber for actuating said signal and for supplying current to his electr'omagnet, a link-circuit, plug and jack connecting means for uniting said line and link-circuit, means res onsive to the connection of said lug an jack to modify the current supplies to said electroma at, and means responsive to such modification to alter the circuit connection at the'acting subscribers substation.

22. A party line telephone system comprisin a telephone line terminating at a centre oflice, a plurality of substations on said line, a 5' al associated with said line at the contra oflice, a controlling elect-romagnet at each substation, means under the control of each subscriber for actuating said si al and for supplying current to his electromagnet, a link-circuit, plug and jackcon necting means for uniting said line and linkcircuit, meaps' responsive to the connection of said plug and jack to modify the current spllied to said electromagnet, and means responsive to such modification to close a conversational circuit at the acting subscribers substation.

23. A party line telephone system comprising a telephone line terminating at a central oflice, a plurality of substations on said line, a transmitter, receiver, switchhook and controlling electromagnet at each substation, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit through the associated electromagnet, a signal at the central office res onsive to the closingof said circuit, a lin r-circuit, plug and jack connecting means for uniting said line and link-circuit, means responswe to the connection of said plug and jack to modify the current supplied to said electromagnet, and means responsive to such modifica tion to alter the circuit connections at the acting subscribers substation.

24. A party line telephone system comprisin a telephone line terminating at a centra oflice, a transmitter, receiver, switchhook and controlling electromagnet at each substation, circuit connections at each substation whereby the removal of receiver from its book normally closes a circuit th'roughthe associated electromagnet, a signal at the central office responsive to the closing of said circuit, a link-circuit, plug and jack connecting means for uniting sai line and link circuit, means responsive to the connection of said lug and jack to modify the current supplied to said electromagnet, and means responsive to such modification to connect the transmitter and receiver of the acting subscriber for conversation.

25; A party line telephone system comprising a telephone line-terminating at a central oflice; a plurality of substations on said line, a signal assoclated with said line at the central oflice, a controlling electromagnet at each substation, means under the control of each subscriber for actuating'said signal and for supplying a uni-directional ,current to his electromagnet, a link-circuit, plu and jack connecting means for uniting sai line and link circuit, means responsive to the connection of said plug and ack to reverse the direction of current supplied to said electroma et, and means responsive to such reversa to alter the circuit connections at the actin subscribers substation.

26. A party line telephone system comprising a telephone line terminating at a central office, a plurality of substations on said line, a signal associated with sai at the central oiiice, a controlling eectromagnet at each substation, means under the control of each subscriber for actuating said signal and for supplying a uni-directional current to his electromagnet, a link-circuit, plug and jack connecting means for uniting said line and link-circuit, means responsive to the connection of said plug and 1ack to reverse the direction of current supplied to said electromagnet, and means responsive to such reversal to close a conversational circuit at the acting subscribers substation.

27. A party line telephone system comprising a telephone line terminating at a central oflice, a plurality of substations on said line, a transmitter, receiver, switch-hook and controlling electromagnet at each substation, circuit connections at each substation whereby the removal of the receiver from its hook normally closes a circuit through the associated electromagnet, a signal at the central oflicc responsive to the closing of said circuit, a link-circuit, plug and jack connecting means for-uniting said line and link-circult, means responsive to the connection for said plug and jack to reverse the direction of current supplied to said electromagnet,

line

5 prising a telephone line terminating at a central 0 cc, a transmitter, receiver, switchhook and controlling elect-romagnet at each,

substation, circui connections at each sub- -stat1on whereby t e removal of the receiver 10 from its hook normally closes a circuit through the associated electromagnet, a sigby Hal atthe central oflice responsive to the closing of said circuit, a link-circuit, plug and jack connecting means for uniting said line 15- and link-circuit, means responsive to the connection of said plug and jack to reverse the direction of current supplied to said electromagnet, and means responsive to such re- .tion.

29. A party line telephone systcm'comprising a telephone line terminating at a central office, a plurality of substations on said line, a link-circuit for connection with said line, a battery connected to said line by the connection of said line and link-circuit, means subsequently under the control of each subscriber to reverse the battery connections to said connected line, means responsive to such reversal to complete a conversational circuit through the substation of a subscriber exercising such control, and means whereby a subscriber on said line already having communicated with the operator may place the battery reversing means under the control of another subscriber on said line, whereby a conversational circuit between said sub scribers may be obtained.

30. A party line telephone system comprising a telephone line terminating at a central office, a plurality of substations on said line, a link-circuit for connection with said line, a battery connected to said line by the connection of said line and link-circuit, electromagnetically controlled means for re versing said battery connections, a switch at each substation for controlling the actuation of said reversing means, means responsive to such reversal to complete a conversational circuit through the substation of a subscriber exercising such. control, and means whereby a subscriber on said line already having oommunicated with the operator may place the battery reversing means under the control of another subscriber on said line, whereby a conversational circuit between said sub scribers may be obtained.

31. A party line telephone system comprising a telephone line terminating at a central office. a plurality of Substations on said line, a link-circuit forconnection with said line, a battery connected to said line by the connection of said line and link-circuit,

electromagnetically controlled means for rethe trsnjsrmttes m ani delver of'the-'actiiig' 'subsdriber for conversa versing said battery connections, a controlling electroma et at each substation, means at each substation for actuatin said reversing means and the controlling e ectromagnet at said substation, means actuated by the reversal of current through said electromagnet to complete a conversational circuit through said. substation, and means whereby a sub scriber on said line already having communi catc d with the operator may place the battery reversing means under the control of another subscriber on said line, whereby a conversational circuit between said sub scribers may be obtained.

32. -A party line telephone system comprising a telephone line terminating at a central oilice a plurality of substations on said line, a transmitter, receiver, svyitch hook electromagnetat ea'ch substation, circuit connections at each substation whereby the removal of the receiver from its book completes a conductive path through the corresponding electroma et, a link-circuit for connection with saig linc, a battery connected to said line by the connection of said line and linlocircuit, electroma etically controlled means for reversing sai battery connections upon the subsequent removal of a receiver from its hook at any substation means actuated by the consequent reversal of current in the controlling electromagnet at the substation of the acting subscriber to connect the associated transmitter and receiver for conversation, means whereby a subscriber on said'line already having communicated with the operator may interrupt the path for battery current through his transmitter to allow the battery;

- scribers may be obtained.

33. A party line telephone system comprising a telephone line terminating at a. central oflice, a plurality of substations on said line, means'at each substation for com pleting a path for battery current between the line limbs, a link-circuitfor connecting with said line, a battery connected to said line by the connection of said line and link- -circuit, means for reversing the battery connections to said line upon the com letion of a path for battery current at any 0 said substations, and means responsive to such reversal to complete a conversational circu t through the substation of the acting subscriber.

34. Aparty line telephone system comprising a telephone line terminating at a central otfice, a plurality of substations on said line, an electromagnet at the exchange for operation to cause completin of a conversational circuit through one 0 said substations, a linkcircuit for establishing connection with said line, and means under the control of the subscriber at said substation after connection between said line and link-circuit to permit the reoperation of said magnet to permit the additional closing of a conversational circuit through another of said substations.

3?. A party line telephone system comprising a telephone line terminatlng at a central oflice, a pluralit of substations on said line, a link-circuit or establishing connection with said line, an electromagnet at the exchange eontrollin means whereby a subscriber at one of said substations may signal and converse with the operator at the central ofiice, means whereby the operator may signal the subscriber at another of said substations, and means under the control of the first subscriber after connection between said line and link-circuit for enabling the second subscriber to cause the operation of said magnet to complete a talking circuit through his substation.

36. A party line telephone system comprisin a telephone line terminating at a centra oflice, a plurality of substations on said line, a subscribers switch at each substation, a link-circuit for establishing connection with said line, means responsive to the operation of one subscribers switch only and the connection of said line and link-cireuit to vary the circuit connections at said subscribers substation and to prevent the subsequent similar variation of circuit connections at any of the remaining substations, and means under the subsequent control of the first subscriber to allow the said variation of circuit connections at another substation in response to the manipulation of the subscriber's switch at such station.

A party line telephone system comprising central ofiice, a pluralit of substation equipments on said line, eac responsive to a reversal of current flow over said line, a linkcircuit at the central office for establishing connection with said line, a supervisory signal associated with said link-circuit, relay mechanism for controlling said signal, a battery, a relay under the control of the substation for varying the connections of said relay mechanism and the battery to the line.

38. A party line telephone system comprising a telephone line terminating at a central ofiice, a plurality of substation equi'pments on said line each responsive to a reversal of current tiow over the line, a linkcircuit at the central office forestablishlng connection with said line, a battery normally having one pole connected to strand of the link-circuit, and relay mechanism under the control of the substation for connecting the other pole of said battery to said link-circuit strand.

A party line telephone system coma telephone line terminating at 21 prising a telephone line terminating at a. central office, a plurality of substation equipments on said line each responsive to a reversal of current flow over the line, a linkcircuit at the central ofiice for establishing connection with said line, a battery normally having one ole connected to one strand of said link-circuit, a relay included in said connection, and means actuated by the energization of said'relay to alter the battery connections to said link-circuit strand.

40. A party line telephone system comprising a telephone line terminating at a central ofiice, a pluralit of substation equipments on said line each responsive to a reversal of current flow over the line, a linkcireuit at the central oflice for establishing connection with said line, a supervisory signal associated with said link-circuit, relay mechanism for controlling said signal, a battery normally havin one pole connected to one strand of said link-circuit, a relay included in said normal battery connection and means actuated by the energization oi said relay to alter the battery and relay mechanism connections to said linkcircuit.

41. A telephone system including a telephone line having two limbs only, a linkcircuit at the exchange, a source of current thereat and adapted to be connected with said line limbs, a switch at the substation of said line for causing a flow of current in one direction through the substation, means responsive to said flow for automatically changing the direction of current, and party line mechanism controllable thereby.

42. A telephone system including a telephone line, a central source of current connected therewith, means controlled by the removal of the receiver at the substation to produce a reversed direction of current flow in said line, and party line substation telephone circuits modified upon such reversal.

43. A telephone system including a lockout party line, having a plurality of substations, means for causing a flow of current over said line from the exchange, switching means at a substation for reversing the direction of current fiow to permit the establishment of a talking connection to the line at said substation, apparatus at said substation operable at-the will of the subscriber to permit the operative actuation of corresponding switching means at another substation of said line to again reverse the direction of current, whereby a second talking connection to the line may be established.

44. A telephone system including a twoconductor telephone line, a substation telephone individual to said line, and a relay circuit at the exchange controlled from said substation to connect said station in conversational relation with the line.

45. A telephone system including a polycontrolled from a substation to connect said station in conversational relation with .the line, and means at a substation for permit- 5 ting control 'of said relay circuit from another substation to connect the latter in conversational relation with-the line while maintaining the first substation in said relation.

46. In a telephone system, a telephone line, a plurality of stations connected therewith, an electromagnet at the exchange adapted to be connected with said line, and means 0on trolled at a substation to operate said elec-- tromagnet to connect said station in conversational relation with said line.

47. In a telephone system, a telephone line, a plurality of stations connected therewith, an electromagnet at the exchange adapted to be connected with said line, means controlled at a substation to operate said electromagnet to connect said statlon in conversational rela- 7 tion with said line, and switching means controlled at said station to alter the operative condition of said magnet to permlt reoperatio'n thereof from another substation of said line whereby both said stations will be in conversational relation with said line.

48. A telephone system'including a polystation line,a relay at each substation of said line adapted to be energized on removal of the receiver to prevent establishment of a conversational circuit with the line at the substation, an electromagnet at the exchange adapted for connection with said line, and

means for operating said magnet in circuit with a relay at a substation whose receiver is removed to deenergize said relay whereby conversational relation with the line is ,established.

conversational circuit with the line at the substation, an electromagnet at the exchange adapted for connection with said line, means for operating said magnet in circuit with a relay at a substation whose receiver is removed to deenergiie said relay whereby conversational relation withthe line is established, anda switching device at a substation in conversational relation with the line for controlling said magnet, to ermit its re-operation from another substation.

.50. A telephone system including a polystation line,'a pole chan ing electromagnet at the exchange adapted or association with said line and for operation responsive to current thereover, and relay means at each substation adapted to establish a talking connection with the line eflective only when said magnet actuates while the respective receiver is removed.

'51.A telephone system including a telephone line having two limbs only, a pole changin relay at the exchange, a central source o current at the exchange, and means for operating said relay responsive to current over sald line, when used as a calling line, to reverse the connections of said source.

52. A telephone system including a polystation line, an electromagnet at the exchange, means at each substation responsive to actuation. of said magnetto connect a substation in talking relation with the line, and means controlled from the substations for permitting the connection of a plurality of substations in talking relation with the line.

53. A telephone system including a calling line and a called line, a plurality of stations connected thereto, a cord-circuit connected in circuit between said lines, pole changing relays for said cord-circuit, means for operating said relays on the closing of circuits over said lines, and circuit connections modified by said pole changing relays.

In witness whereof I hereunto subscribe my name this 5th day of March, 1907.

HARRY G. WEBSTER.

Witnesses:

CAROLYN WEBER, THOMAS H. FERGUSON.

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