US1208718A - Telephone system. - Google Patents

Description

f A. H. DYSON.

v TELEPHONESYSTEM. APPLICATION FILED MAR.19, l906. RENEWED APR. 17.1'91-2.

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i/.2 j! 4 Y ff 6p l? 5 MHH f@ 6@ 5] Q A l 46 514i- 5655 6l 67a T. M/tf` A.;.H. DYSON...k TELEPHONE SYSTEM. APPucmoN min MAR.1 9. 190s. RENEwEu APR. 17`I 1912.

1 208,7 1 8.. Y Patented Dec.v 1,2, 1916.

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i `l I A. H. DYSON.

TELEPHONE SYSTEM. y APPLICATION FILED MAR. I9. 1906. RENEWEU APR. I7.' 1912.-

1,208,718. `melma De@.12;1916.

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AQ H. DYSON.y TELEPHONE SYSTEM. I

Pnjn, 1912.'

" ,g Patented 1360.121916.

APPLICATION FILED MAR. I9. 190i?. RENEWED A 7 sains-sum 44.

A. H. DYs0N. TELEPHoNE'sYsTEM. I APPLICATION FILED MAR. 19. 1996. RENEWEDY APR. 17.*1912.

1,208,718. Patented m0121916.,

ISHEETS-SHEET 5. I

A. Hg'DYsoN.

TELEPHONE SYSTEM. j j APPLICATION FILED MvAR.19,V1906. RENEWED APR. 17.1912.

Patented Dec. 12, 1916;

v I V zsHEETs-SHEET A. H. DYSON. l TELEPHONE SYSTEM.-

APPLICATION FILED M-AR. I9, 1906. RENEWED APR- l?. 15H2. I

1,208,718. Patented B60121916. 1

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www N f UNITED sTATEs PATENT oEEIoE.

ALFRED H. DYSON, OF CHICAGOJIVLLINOIS, ASSIGNOR,'BY. MESNE ASSIGNMENTS, T0 "HELLO-GG SWITCHBOARID & SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

vPatentedpee. 12, 1916.

Application filed March 19, 1906A, Serial N0. 306,817'. Renewed April 17, 1912. Serial N0. 691,505.

To all whom t may concern y Be it known that I, ALERED H. DYSON, residing in Chicago, county of Cook, and State of Illinois,`have inventednew anduseful( Improvements in Telephone Systems, of which the following is a specification.

-My invention relates to multiple switchboard systems and' more particularly to the means employed for signaling a called subscriber that'his attention is wanted and for signaling the. calling subscriber that the line wanted is busy, should such be the case.

The object of my invention is to provide a structure, capable of employment for party line service, in whose use thel operator may,

on'learningi the called subscribers number,

` insert the calling plug immediately into the jack of the wanted line, without waiting to preliminarily test the line, `and perform the switching operation for ringing the subscriber wanted, automatically controlled means being provided to render this actineffective, should the line be busy, and to extend to the calling subscriber a busy signal.

I am aware' that'it is not new to provide means for automatically extending a calling signal or a busy signal,the signal extended being determined by the engaged `or disengaged condition of the called line, but as far as IA am aware, it is new to provide for the automatic extension of busy signals in combination with structures employing manually operated party line ringing keys.

My invention involves primarily special apparatus connected with the operatorsY cord circuits, and may be employed in connection with a plurality of known forms of line circuit arrangements without change therein,

being thus adapted for readyy installation in connection with existing telephone exchange systems.

Referring to the drawings, Figure 1 illustrates a side view of a`key structure employed in connection with my invention; Fig. 2 is a left-end viewy thereof, omitting the listening cam L and its springs and the ringing springs of plunger 722; Fig. 3 is a right end-view of the key structure of Fig. 1. Fig. i shows in perspective the upper portion of spring-lever 61. 5 is a front View of arm 57 employed to actuate the spring-lever G1. Fig. 6 shows the association of the. circuit changing springs with slvringleveril adaptedfor use in connection with. the circuit ofy Fig. 14:. Fig. 7

illustrates two'telephone lines and operators cord connecting apparatus arranged in accordance with my invention. F ig., 8 shows the application of-my invention to a var ing form of telephone exchange system. 1g. 9 shows a form of key structure that may be employed in carrying out my invention. Fig. .L0 shows a left end view thereof, the listening cam and its springs being omitted. F 1g. 1l is a right end view showing the spring combination of the 'structure of Fig. 9. Fig. 12 shows a pair of telephone lines and cord connecting apparatus adapted for use in connection with the keys shown'in Iiigs. 9 to l1. Fig. 13 shows a modification of the cord circuit 'structureof Fig. 12. Fig. ll illustrates a varying form of cord circuit embodying my invention. Fig. 15 illustrates another form of cord circuit embodying my invention. Fig. 1.6 illustrates a key structure adapted to be employed in connection with the circuit arrangement of Fig. 15.

The key structure shown in Fig. 1 cornprises the usual listening cani L adapted, when thrown over, to connect the operators talking set with the cord strands. In addition, plungers b2, c2, d2 and c2 are provided, as is usual in selective party line ringing systems, each being adapted, when operated, to cause' the'bell of 'one subscribers substation on the called line to ring, and of one only. Two magnets 21 and 26 are provided for controlling the operation of the plungers, magnet 21 being arranged to be operated when connection is made with a called line and to hold a depressed plunger in its ringing position until the called subscriber responds or the operator withdraws the plug from connection with his line, a response failing. The other magnet 26 is operated only in case the called line is busy, and when so operated prevents a depressed plunger from assuming its ringing position, so 'that interference with existing conversations by ringing current is prevented., In Fig.` l, parts of plungers b2 and c2 and their assoformer, 2l, is provided with an varmature and a spring 54 fastened thereto, interlockciated mechanisms are omitted, so as to dising with rocher arm 51 as shown in Figs. 1 and P.. The said arm 51, pivoted at and 53, has four pawls, two of which are visible in Fig. 1 beneath plungers b2 and e2, the other two being concealed by c2 and di. When the armature of 21 isat normal, as shown in Fig. '2, the pawls of 51 are out of engagement with the plunger-s, while the upper edge of 51 engages the shoulders 60 of the plungers preventing their depression. until such time as magnet 21 becomes energized, which occurs as soon as connection is made with a' called line, when spring 5t rocks arm 51, so that it disengages shoulders 6G while its pawls press against the plungers. This is to prevent the operator from depressing a plunger until connection has been made with the called line, so that, should the line be busy, magnet 26 will be actuated in time to prevent a depressed plunger from assuming its ringing position.

Magnet "26, by its spring (Figs. l and 2) fastened to its armature, interloclis with rocher arm 4S. whose four pavfls-two being shown complete in Fig. 1 and two as broken (itil-are normally held .disengaged from" their respective plungers. Then 2G is actuated. spring moves arm 4S about its pivots lil and 50. so' that the said pawls press against theirplungers. As shown in` Figs. l and 3, aims i8 and 51 are disposed on opposite sides ot the plungers.

The plungers and the parts individual to them being identical, but one. d2, will be specifically described. lt journaled to lmounting plate (32 and support (33. and when depressed and released, its spring 59 tends to raise 1t to its normal position shown. In addition to shoulder 30 before referred to,

Ashoulder 56 is provided` which descends be low the pawls of arms 51 and 4b on depressionot' the plunger. whereby its ascent is rendered controllable first by magnet 21, and thereafter b v magnet 26. Fastened to the plunger is arm 5T whose T shaped extremity fitting into the I shaped orifice of spring lever ('1 (Figs. 1, l, and 5), on downward stroke ot' plunger d, passes on the left side ot' (il, while on the upward stroke it passes on the right side ot' (S1 to a position where it causes the closure of contact 4l-i5. This is the ringing position ot' the plunger, and in this position the plunger is held (provided the line wanted is idle) due to the energized condition ot' magnet 2l and the consequent engagement of arm 51 with lshoulder 5G. until, on the response ot' the subscriber, l1 is deenergized. T ie plunger also carries arm 5S which extends through the traineas shown in Fig. 3.2 lvhen the plunger is fuliy depressed 5S. engaging its particular angular' surface of rocker arm G7, pivotally connected to the.V vertical and pivoted supporting arms shown` moves the said arm 37 to the right, which, by its exkmore; 1s

tension 67, moves mechanically connected springs 36 and 237 to their alternate positions. magnet 2G therefore energized when the plunger is depressed, arm i8 by its pawl engages shoulder 5G and holds the plunger practically completely depressed, so that springs 86 and S7 continue in their alternate positions, while arm 57 is prevented from assuming its ringing position.

Having described in detail the special mechanism employed in connection with my invention, l shall describe the circuit drawings, in which, for the sake of clearness, but few mechanical elements, and those in diagrauimatioform, are shown, without cross references to Figs. 1 to 5, assuming that the mechanical combinations are borne in mind. Similar parts, appearing in Fig. 7 and Figs. 1-5, have corresponding reference characte'rs.

In Fig. T, I have illustrated a telephone line extending from substation B to the eX- change and there provided with 4a well known line circuit arrangement. The mechanism at B includes hook-lever 1 normally maintaining the condenser and bell in bridge of limbs' and 3, and adapted on removal of the receiver to open the bell circuit and connect the transmitter and receiver with the line limbs.` The various vground connections illustrated at the exchange indicate connections to the grounded side ot battery by the ofiice return. The line limbs 2-3-of substation B are connected to the opposite sides of battery 65, the line re- Should the called line be busy and i lay i, controlling line signal lamp 5, being connected between limb l and the active side of battery. The cut-ofi relay (i, connected from ground to the sleeve contacts 8 of the spring heks, when actuated, by its armatures opens the normal connections of limbs i! and 3 and connects them to jack contacts S and T. A second telephone line is shown, to which are connected substations B, C, D and E, to each of which the description ofrsubstation B also applies. The central office circuit of this line is similar-to that of the line oi B. An operators cord circuit is shown including "an answering plug having tip and sleeve ontacts 9 and 10, and a calling plug having tip and sleeve .contacts 11 and 12. Associated with the answering plug contacts are relays 13 and 1i, jointly controlling the answering supervisory signal 15, while, in association with the calling plug contacts, are relays 16 and 19 controlling the calling supervisory signal 20. Relay 16, by armature 1T, further controls a contact in the sleeve cord strand, norlogs sensitive to the busy condition of a called line. By its armature 24, relay 22 controls the keyinagnet 26. Armature 23 controls the connection of busy machine 39 with the line of the calling subscriber. The circuit of magnet 21 extends through spring 31 of relay 27 and its normal contact, which latter relay has an actuating winding 29, normally connected to tip contact 11 ofthe plug and conductor 66, and a locking winding 28 controlled by armature 30. Conductor 66 is adapted for connection with any of the ringing springs 40, 42, 44 and 46.

The generators b, c, d, and e, deliver current of lvarying frequencies and the call@ bells at substations B, C, D and E are tuned so that each is responsive only to current of the frequency delivered by' the generator' designated by the corresponding small letter. Such a harmonic selective ringing sys- -tein is vdescribed in U. S. Letters Patentto Wm. lV. Dean, title, Party line telephone system, No. 779,533, issued Jan. 10, 1905.

By means of the plungers b2, c2, Z2 and 62,'

the operator can connect the proper generator with an idle called line to ring the subscriber wanted. Interrupters b, c, d and e are provided to alternately interrupt and close connection between springs 40, 42,

44, and 46 and their associated generators,

whereby the substation bells are intermit-V tently caused to ring. In addition to the two brushes effecting this are provided two additional brushes, so arranged that conductor 66 is always grounded when one of springs 40, 42, 44 and 46 is connected to it, in order to insure that when the called subscriber removes his receiver, circuit will instantaneously be' completed through relay 27, whereby magnet 21 is denergized to disconnect the generator. The remaining connections will be understood best from the description of the operation.

Assuming that subscriber B desires to converse with subscribe-r l), the removal of the receiver'at substation B completes circuit throi-igh line relay 4, the current travel;

' The attracted armature of relay 19 also efretracted armature renders signal 5 inert) and by engaging their alternate scontacts, connect limbs 2 and 3 to contacts8 and 7. Relay 14 attracts its armature, which would cause the display of supervisory signal 15 were this not prevented by the attraction of the armature of relay13, now energized by current through its winding, contact 9 7, armature of relay 6, hook-lever .1, returning through the other armature of relay 6, contact 810 and through relay 14 to battery.

The operator, ascertaining'in the usual i manner what subscriber is wanted, inserts the calling plug into a multiple jack of the line connected to the said subscribers station closing' contacts 11-7 and 12-8. Cur-A rent flows from ground, through cut-01T relay 6 of the called line, Contact 8-12, its normal Contact and spring 37,- relay 19 to battery 65. The attracted armature of relay 19'closes circuit 'from ground, through spring 31 and itsfnormal contact, key magnet 21 and to battery, whose actuation causes plungers '62, c, cl2 and e? to be unlocked.

9G fects the display of supervisory signal lamp 20. The operator now depresses plunger d2 v to its full extent, which throws over springs 37 and 36 to engage their' alternate contacts. To this point, the operation of the system is the same whether the called line is busy 0r idle.

rlfh'e described movement of spring 36 connects the winding of test relay 22 with the sleeve strandof the cord and through con` 13G tact 12 with the sleeve contacts 8 of the Aspring jacks ofthe called line. The actuation described of spring 37-disconnects teinporarily the sleeve strand of the cord from the active side of battery 65 and completes 105 a new path for current through relay 19 to ground.

Assuming first' that the called line is idle, it will be observed that the grounded Winding of relay 22 is connected through con- 110 -tacts 38-36, 12-8, to the grounded winding of cut-olf relay 6 of the called line. No How of current results through relay 22, and the depressed plunger Z2 ascends to the ringing position because, owing to the dener- 11E gized condition or relay 22, key magnet 26 remains inert. The contact of' springs 37 and 36 with their alternate contacts being in A this case momentary only, they resume their-normal positions` circuit being again #il completed from ground at the called line, through cut-otl`1 relay6, contacts 8-12. spring 37, relay l5) to battery. The attracted armatures ot' cut-oliA relay 6 complete circuit` for current from generator fl. through interrupter fl', contact 44-L5,\ plunger rl2 being now in ringing position` .through winding 29 of relay 27, itsnornial contact and sarin armature 25 of relav 22 con- J e .l 7

tact 11-47, the attracted armature, of relay 1130 6, limb 3, through the call bells and condensers of substations B, C, D and in parallel, returning over limb 2, the attracted armature of rela-y 6, contact 8 12, spring 37, relay 19, to battery. Due to the substation condenser the relay 27 is not energized; and the frequency of current being out of time with the call bells of all the substations other than- D, the subscriber at that substation is alone signaled. By the removal ot' the receiver at substation D, circuit is instantly completed from ground at the eX- change, tliroughone or the other of the brush pairs of interrupter cl', contact L11-15, winding 29 and, following the before traced path of ringing current, to battery 65. T his being direct current, relay 27 is energized, whose attracted armature 30, engaging spring 31, completes ay locking circuit through winding 28 for relay 27 andiininediately thereafter opens the circuit of key magnet 21, whose deneigization allows the return of plunger Z2 to its normal position. The attracted armature 32 of relay 27, engaging spring 33, completes the talking circuit of the tip strand of the cord circuit and thereafter opens the ciicuit'of winding 29 of relay 27 .A On the closure of contact 32-33, a path for the flow of current was established through the grounded winding of relay 16, over tli'eftalking circuit as indicated by the heavy lines, to limb 3 of the line of subscriber D, returning over limb 2 and through relay 19 to battery: The attrac'ted armature 18 of relay 16'opens the,

circuit of supervisory lamp 20 which is thereby put out, notifying the operator that the response has been made. The attracted armature 17 of relay 16 completes the talking circuit of the sleeve strand of the cord circuit, and the two subscribers are iiow in conversation through condensers s and s', the talking circuit being indicated from substation B to substation D, through the exchange, by the heavily marked conductors, current for energizin heir respective transmitters being supp ied from battery 65 through the sleeve supervisory relays 14 and 19 respectively, the return path being traced through the relays 13 and 16 respectively.

When subscriber B replaces his receiver, circuit is opened through relay 13, whose retracted armature effects the display of lamp 15; and when D replaces his receiver, circuit is opened through relay 16, whose rcti'acted ariiiatuie 18 closes circuit through Alamp 20. The operator, observing the simultaneous display of the two supervisory signals, withdraws the answering plug from the callingline, effecting the denergization of relays 6 and 14, while the withdrawal of the calling plug interrupts circuit through relays 6 and 19. The retracted armature ot'. rela-y 19 opens circuit through lamp 26 and also through the locking winding 28 of relay 27, whose retracted armature 3() allows spring 31to engage its normal contact, again placing li'ey magnet 21 under the control ol relay 19; while the retracted armature 32 of relay 2T allows spring 33 to engage its normal contact, again placing conductor 66 in operative relation with tip contact 11 ol the calling plug.

The insertion of eitiieian answering plug or afcalling plug into the spring jack of a line causes a. flow of cui-rent ilii'oiii battery 65, through the respective sleeve supervisory relay 111 or 19, to ground through the cut-oli relay 6 of the line. Owing to thc resistance of the cutoiil relay Winding, sleeve contacts 8 of the line spring jacks are.I under this condition, of a potential other than that of ground. Assuming that, when the operator insert-ed the calling plug into a sliring 'ack ,of the line of subscriberl), the `just described condition existed, upon the complete depression of d2 throwing over springs 37 and 36 to engage their alternate conzacts, the raised potential oi the sleeve contact 3 of the jack, into which the calling plug` was inserted, would cause a iow ot current through sleeve contact 12 of the calling'plug now inserted in the busy line, through contact 36-3S, the winding of test relay 22 to ground. The attracted armature 211 of this relay then completes circuit through busy magnet 26, whose actuation prevents the return ot plunger Z2 to the ringing position by holding it practically fully depressed so that springs 37 and 36 are continued in their alternate positions. The attracted armature 23 of relay 22 completes circuit from interrupter 39, through the induction coil and condenser, through the sleeve Vstrand condenser s and contact 10-8 to the calling line, whereby the calling subscriber is notiiedtliat the line 'wanted is busy. lle thereupon replaces his receiver, thereby displaying supervisory relay 15 and advising the operator that the line should be disconnected. The withdrawal of the calling plug opens the circuit of test relay 22, whose retracted armatures 23 and 211 disconnect the busy machine 39 and denergize key magnet 26, whereupon plunger d2 ascends to a position where springs 36 and 37 assume their normal positions. As soon as 37 disengages its alternate contact, relay 19 becomes inert,'and the retracted armature opens the circuit of key magnet 21 whose denergization allows the return of plunger (Z2 to normal.

In Fig. 8, I have illustrated a telephone @Xchange system of well known character,

employing three conductor spring jacks andl cord circuits in association with the structure. of my invention. Salient features differentiating this system from that shown in Fig. 7. include the placing of cut-olf relays 6a in circuits independent of the talking circuits, tlie supervisory signals 15a and 20* being placed in serieswith the cut-oil' relays on connection' of the plug terminals with the line jacks. The supervisory relays 13a and 16a, having the functions of rendering the supervisory signals inert when the substation circuits are completed by the removals of the receivers', render them inert by shunting them by resistances vl5" and 20b respectively. The two connected subscribers lines in Fig. 8 are induetively united for conversation by windings r, r', of a repeating coil, instead of bycondense'rs s, sf, as shown in Fig. 7;

Briefly, the operationol Fig. 8 is as follows: When subscriber B initiates a call, relayl1 and lamp 5l are energized. On the insertion of theanswering plug into the jack of the calling line, the placing in series of the signal lamp l5a with cut-olf relay 6 (displaying it), relay 19a to battery 65a..

' The attracted armature of relay 19a effects energization of lkey magnet 21, releasing the key plungers and setting the ringing position pawls against the plungers. The op,- erator, now depressing plunger al?, causes Asprings 37 and 36 to engage their alternate contacts, the closing of contact E38-36, placing test relay 22 in operative relation with sleeve 12b of the calling plug. lf the plug of another cord is already connected to the called-for line, contacts 8b and 12b will be at 1 a potential other than ground, due to a flow of current from the other cord, through the resistance of cut-ofi' relay 6a of the called. line, to ground. Relay 22 will therefore be energized, and its attracted armatures will connect interrupter 39 with thelcalling line.

and cause the actuation of key magnet respectively, to transmit the busy signal to subscriber B and prevent plunger' Z2V from assuming its ringing position. Subscriber l?, replacing his receiver', thereupon deenergizes relay 13a, vwhose retracted armature removes the shunt of l5" from signal 15a'. Both signals being displayed, the, op-

erator removes-the two plugs and the lappa-l ratus resumes its normal condition. Should, however, the called line be idle, 8" and l2b will be at'thc potential of ground, relay 22 `and magnet 2G remain (lenei'gizerl, and plunger d2 assumes its ringing position, whereby contact @Mw/45 is closed and ringing;r current `projected froxngenerator d,

through' winding 29 of relay 27,over the called line to ring the bell of subscriber D, as before described. On the removal of the receiver at D, direct current flows'v from ground, through contact i4-45, winding 2 9, contact 11a- 73, through lever l at D, returnin' through 8a, 12a., supervisory relay 16a to attery 65a. Armatures 30 and 32 of relay 27 operate to denergize magnet 2l, to allow the return of plunger d2, and to cornplete the talking circuit of the tip cord strand. The attracted armature of relay 16a` shunts signal 20l to of resistance 20".

` When subscribers B and D replace their receivers, relays 13a and 16a are denergized,

and their retracted armatures vremove the render it inert by means shunts of resistances l5b and 20b from about `signals 15a and 20a, whose simultaneous display notifies the operator to remove the answering and calling plugs, which causes the line circuits and the cord circuit to resume their normal positions.

The key structure shown in Figs. 9, 10

and ll includes the four plungers b3, c3, d,

and e3, common to which are the two levers 93 and 94 shown in Fig. 10 which are bound together by the plate 97 yand provided each with four pawls for the four plungers. In this structure no locking pawls are required. Armature 92 of magnet 75 interlocks with lever 93 and when retracted, holds the pawls of 93 out of contact with the plungers and those of 94 in contact therewith. A depressed plunger as d will be held in itsV fully depressed position, closing contacts l01l02 and .N3-10i by the engagement oi' the appropriate pawl of `9e with' its upper shoulder, until the actuation of magnet 75 occurs whose attracted armature actuating 93 and 94 allows upward movement of (Z3 until its said upper shoulder engages 93.

In this position it is locked until denergi-- sation of magnet 7 5, which only occurs when the operatr removes the plug from the called line. This is the indicating position, the top of the plunger being held somewhat below the tops of its fellows, so that the operator 'may know which of the .party substations she has signaled until disconnection is finally completed. Controlled by the magnet 75 as shown in Fig. 1l by means of a stud upon lever are circuit changing springs 95, 9G and 98, the attraction of armature 92 causing them to respectively engage their associated springs.

The above described key is employed in connection with the embodiment of my invention shown in Fig. 12. The description ,of the line circuits given for Fig. 7 applies 'to those of Fig. 12, as does the there gwen In the structure of Fig. '12 and in the succeeding figures, a polarized relay 88 is employedL whose winding is Connected to a battery tap having a. potential of approximately 8 volts, taken as shown from the usual 24 volt common battery, although obviously a separate battery may be employed. Its operation in Fig. 12 and Figs. 18, 14 and 15 is the same, and as follows: A flow ot' current from the 8 volt tap through relay 88 to the return side of battery through the cut-off relay of an idle line, causes the actuation of armature 89 to the left. A flow of current through relay 88 in the reversed direction will cause the actuation of 89 to the right. Such liow will result when the calling plug of the cord circuit is connected to a. busy line as in such case the 2l volt tap of battery will be connected through the already connected cord tothe sleeve of the tested jack, and owing to theresistance of the cut-otlv relay of the busy line, which in such systems is ordinarily 500 ohms, the tested sleeve will be at a minimum potential of about 1l volts, the minimum occurring when the substation receiver is oil the hook. This potential being in excess ot 8 volts con nected to the opposite end ot the winding of 88 a. reversed flow is produced therethrough. The actuation of armature 8S) to the left etllects the energization of the sleeve relay 82 to place by armature 83 the ringing apparatus, when a plunger is depressed, in operative relation with the cord and to cause by armature 8l the display ot supervisory signal 20. The arrangement to secure intermittent ringing of the called substation bell shown in Fig. 12 includes the constantly rotating interrupter 87 controlling, whep connection is made with an idle line, the circuit of relay 86, whose attracted and retracted armature alternately connects and disconnects t-he generator lead from the tip cord strand. The actuation of armature 89 to the right ctlects the energization of relay 78 to actuate sleeve relay 82 and key magnet 75. the latter allowing the return ot a depressed plunger to its indicating position whereby the ringing apparatus is instantly removed from operative relation with the cord. T he energized relay 76, by armature 80, also completes a circuit from busy machine 89 to the calling line. and by armature 79 a locking circuit for itself only destroyed on the removal of a` calling plug'.

Assuming B desires his line connected to the. line ot-D, he removes his receiver and the operator, answers and learns his want as described in connection with Fig. 7. Having depressed the plunger associated with the ringing current ot' proper frequency to ring the bell of the wanted subscriber, the operator then inserts the calling plug in a iack of the line of D. Assumingr this line idle, relay 88 attracts 89 to the left closing mesme circuit through relay 82 Whose attracted armature 85 denergizing relay 88 establishes a locking path through its winding from the 24 volt battery tap through spring contacts of relay 7 G, contact 12-8 through high wound relay 6 (attracting its armatures) to ground. All jack contacts 8 of Ds line have their potential raised as before mentioned. Attracted armatures 88 and 84 respectively complete the tip talking strand of the cord and effect display of lamp 2O.l The operator having depressed plunger ci', Fig. 9, contacts 101-102 and 103-104 are closed and the bell at substation D is rung by current from (l traversing contact lOl-102, armature of 'relay 86 when attracted, armature 88, armature 78, contact 11.-7, armature of relay 6, substations B, C, D and E in parallel, returning through contact 8-12 and relay 82. As soon as D removes his receiver and interrupter 87 is in such position that relay 86 is denergized, current flows from ground through relay 16, the retracted armature of 8G, armatures 83, 78, -11-7, through transmitte` and receiver at D returning through 8-12, armature 85, relay 82 to battery. Attracted armatures 17 and 18 respectively complete the talkingv circuit of the sleeve cord-strand and put out lamp 20, while armature 18 in addition closesV circuit through itself from ground, armature 84 of relay 82, key magnet 75 to battery. The consequent attraction of its armature locks magnet 7 5 by current through armature 84 of relay 82 to battery. The attracted armature of 7 5 also moves levers 93 and 94; (Fig. 10) so that plunger Z3 assumes its indicating position and genera-y tor d is cut-ott. At conclusion of conversation the replacing of the receiversca uses the denergizations of relays 18 and 16,and on the resulting displays of lam is 15 and 2O the Operator removes the plugs ilenergizing relays (i, 14 and 82, the retracted armature 84, of the latter denergizing magnet l which causes plunger fla to return to normal when all apparatus is restored. It during the time contacts 11-7 and 1.2-8 or 9-7 and 10-8 are closed another operator connects the calling plug of a second cord circuit to a spring 'jack of either line, a reversed flow o1 current takes place through relay 88 of this second cord and its armature 89 engages contact 91 to close circuit through the right hand winding otI its relay 7G whose attracted armatures 77 and 78 respectively y actuate key magnet 7 5 to place a depressed plunger in indicating position and open the tip strand of the cord to render impossible interrul'ition of an existing conversation by` '3 generator current. and also the operation of relay 1G which would otherwise occur. Attracted arn'iatun` 80 of relay 76 connects busy machine 39 with the sleeve strand -of the answering plug to signal the calling substation, while armature 79 'opens circuit through vrelay' 88 and establis es a locking circuit for its relay 76 through 'the/cutoff relay 6 ofthe busy line, inorder'that relay 82 may continueenergized by Current over the circuit established by the attracted armature 81,v whereby the continued display of lamp 20 is secured. The calling subscriber 'y generator d (Fig. 14)-.to be depressed, conhearing the busy signal replaces his receiver whereupon signal lamp 15 is displayedand the operator'removes the plugs. I? The calling end of the cord is laced at normal byl the resulting opening ci) hand or locking winding of relay 76, whose retracted armatures de energize 82 and 75. In Fig. 13 I have `-illustrated a modification of the cord circuit shown in Fig. 12. Its method of operation is substantially the same as is the arrangement of parts, the difference being that springs 96 and '98 shown in Fig. 11, and not employed in connection with Fig. 12, are here employed to complete the talking circuits of the two cordV strands, the employment. ofarmature 17 of relay 16, Fig. 12 being here dispensed with. It will be observed that'the talking circuit ofthe tip cord strand in Fig. 12 asses serially through armature contacts o relays 86, 82 and 76. In Fig. 18 a' talking circuit is .provided in parallel with that of Fig. 12

containing the single 'switch contact of spring 98 (closed oni'the actuation of key magnet 75) and possible trouble due to the presence of the three series contacts in the talking circuit above referred to, is obvialted.

In Fig. 14 -I show my invention carried out in a form employing the polarized relay 88 and adapted to be used in connection with the key structure of Figs. 1 to 5; with the exception that key magnet 26 and its lever 48 are not employed, while fastened to lever 61 of each plunger is to .be provided an addicircuit through the left called line.

tacts 44-45 and 99% 100 will beclosed and current will'intermittently flow `from generator d through armature of relay 86, when retracted, armature78fof relay 76 to the On the responseof the subscriber, relay 16 is actuated by current passing through the armatureof relay 86 When attracted, armature 78 and over the called line. The attracted armature 18 of relay 16 puts out lamp 20 and establishes a flow of currentto energize relay 21a whose attracted armatures open circuit through key magnet-21-(allowing the return of a depressed plunger to normal',` whereby contacts 44-45 and 99-100are opened) and com. plete the talking circuit ofthe tip cord strand. Should the called line, however, be busy when the calling plug of Fig. 14 is connected to a spring jack thereof, armature 89 of relay 88 engages contact 91, and relay 76 is energized whose armatures 78, 79, 80 and 81 operate in a manner corresponding to similarly designated, armatures of Fig. 12, while armature 81EL opens a contact in 90 the circuit of key magnet- 21 and prevents its actuation which would otherwise occurwhen relay 82 attracts armature 84. The

plungers shown in Fig. 1 remain therefore whereby the cord apparatus is restored to tional switch spring 99 with its associated Contact 100, as' shown in Fig. 6, adapted when a plunger is in its ringing position to connect interrupterf87, Fig. 14 with relay 86. The line circuits shown in Figs. 7 and 14. On connection made with 'an idle line by the calling plug of Fig. 14, armature contact 89-9O of relay 88 is'closed to energize relay 82 whose armature 85 establishes locking path for current for 82 from the 24 volt battery tap, through thev switch springs of relay 76 and the cut off relay 6 of the called l-ine (Fig. 12) which flow puts the busy potential on the sleeve contacts of the spring jacks. The attracted armature 84 of relay 82 closes circuit through lamp 20 displaying it, a branch circuit through key ll2 may be employed in connection with Fig.

magnet 21 being also established to actuate 21 which unlocks the plungers (see Figs. 1 and 2) and places the pawls of lever 51 in position to hold a depressed plunger in ring ing position. 4Assuming the plunger of normal, the calling subscriber having meanwhile for a short period heard the busy signal in his receiver.

Referring now to Fig. 16 this illustrates a key structure adapted for use in connection with Fig. 15 and includes four plun' gers b4, 0*, d4 and e,-employed respectively in connection with generators b, c, l and e 110 in F ig. 15. Each plunger is provided with Aa pivoted pawl 105 linked to lever 107. The

arrangement of all the plungers being similar, that of d4 only will .be' particularly described. When depressed, the plunger causes springs 101 and 103 to engage respectively 102 and 104, the plunger being thereafter 'locked in its depressed position by the engagement of pawl 105 with pin 106 inserted in the plunger. The depressed plun- 1 20v ger (Z4 remains in this position until the cord with which the key, Fig. 16, is associated is again employed in completing a call, when the operation of the listening key L, moves lever 107 and pawls 105 to the right so that 125 a depressed plunger returns to normal.k )Vhen key LA is restored spring 109 carries lever 107 and pawls 105 to normal.

VThe cord circuit structure shown in Fig.- 15 is adapted for employment in connection'-l 190 plunger that may with the line circuits of Figs. 7 and 12. lThe operator having connected answering plug contacts 9,1() with contacts 'T and ot the jacl; ot' the calling line, by throwing over listening cam L (Fig. lo) restores any be depressed to normal. Learning the number ot' the called subscriber assumed to be D she inserts the calling plug into a multiple jack o't' the line connected to his substation and depresses the plunger d* which causes contacts 101-1tl2 and 1023-104 to be closed, (Figs. 15 and 1(3).

It' the called line is idle, armature 89 of relay 88 engages contact 90 to energize sleeve relay whose attracted armature S5 opens circuit through SS and locks the said relay by connecting its winding to ground through the cut-oli' relay l5 o't` the called line, and whose attracted armatures Sl, S2 and S2" respectively close circuit through lamp 2() displaying it, connect generator (I with t-ipl 11 ot the plug and place interruptor 8T in operative relation with relay 86 whereby said relay is alteriiatelyv energized and deenergized, and by the operatioirof itsl armature, current adapted to cause the ringing of the bell olrsubstation D is intermittently supplied to the called line. When now the called subscriber responds by ren'ioving his receiver, as soon as interriu'iter 8T reaches ai position 'such that relay HG energized,

current will 'iow trom `ground through relay 1t (whose attracted armature 1H eifaces lamp 2() and causes encrgizatmn ot' relay 110) tl'irough the actuated armature ot' re-.

lay 8G. armature of relay 82, armature TS of' relay T13 to the tip contact 11 ot the plug, over the line returning through sleeve contact 12 and windingr ot' relay H2 to bat.- tery. Aitracted armature 114 of relay 11() disconnects relay Sh from interruptcr Si' and establishes a new path through said relay 8G so that its armature continues attracted. Armature 113 establishes a locking circuit for relay 110, while its armatures lll and 112 complete. the talking circuits oi theI tip and sleeve strands ot' the. cord ci-rcuit vrespectively', llhen at the conclusion of conversation thc subscribers replace their receivers, relays 13 a nd llbecome deiinergized, lamps 15 and 20 are displayed, and the operator withdrawing the two plugsirom the. line jacks ell'ects the deiinergization ot' relay 14- and whereby the cord circuit is restored to normal. i

lt the calledvline is busy when the calling plug of Fig. 15 is connected to its spring jack. relay 88 closes contact 8th-Q1 to energize relay 76. ot whose armatures 81 causes energization of relay 82, .79 disconnects armature S5 trom the sleeve contact 12, and locks relay TG by current to`grcund through the cut-olil relay ot the called line. Armature 7S disconnects tip contact 11 trom the generator circuit to be established by encrthe particular gization of relay 82 and as this occurs before relay 82 is energized the existing conversation is not interrupted by generator current. Armature 80 of relay 76 connects busy machine 39 with the calling line and the subscriber in response to the signal replaces his receiver. Lamps 15 andvQO being being then displaced the operator Withdraws the plugs, restoring the apparatus to normal.

It is not my intention to limit myself to devices and arrangements herein shown and described, as the principle of my invention is capable of varying cmployments, but

What I do claim and desire to secure by Letters Patent is:

1. A telephone exchange system including a telephone line, a signal at the exchange adaptedto be displayed responsive to currents over said line, a second telephone line, a plurality of substations connected therewith, operators means for unitin said lines, apparatus' connected therewith or selectively ringing a desired one of said plurality of substations, and means responsive tothe busy condition of said second line t0 render said apparatus ineffective and to extend a signal. y

2. A telephone exchange system including a telephone line, a signal at the exchange adapted to be displayed responsive to currents over said line, a second telephone, line, a plurality of substations connected therewith, operators means for uniting said lines` apparatus connected therewith for selectively ringing a desired one of said plurality of substations, means responsive to the busy condition of'said second line to render said apparatus ineffective and to extend a signal, and means effective upon a response at a called substation to render said 'l apparatus ineffective. y

A telephone exchange system including party lines, operators means for uniting said lines for conversation`y apparatus associated therewith for selectively signaling the parties of said lines, and means responsive to the busy conditions of said lines to render said apparatus ine'ective and to extend signals.

4. A telephone exchange system including telephone lines, a plurality of substations connected to some of said lines, multiple terminals of said lines at the exchange, signals responsive to vcurrents over said lines, operators link-circuits adapted for connections to said terminals, the normal electrical conditionfof the terminals ot a line when alink-circuit' is connected to one, party line signaling mechanism associated with said link-circuits for projecting selective signaling current over said lines, and electro-magnets for said linkcircuits sensitive t0 the altered electrical c0n,

meansl for altering i ditions of sai'd terminals to prevent "the pro- Ations to said terminals, means for the normal electrical condition of the terminals of a line When a link-circuit-is connected to one, party-line signaling mechanism associated with said link-circuits for projecting selective signaling current over said lines,electromagnets for vsaid link-circuits sensitive to the altered ,electrical conditions of said terminals to prevent the projection of said current and extend signals, and electro-magnets for said link-circuits controlled by responses at called substations adapted to terminate `the projection of signaling current over said lines.

6.v In a telephone system including telephone lines, signals therefor at theexchange, and operators` link-circuits for connecting said lines, the combination, with a line, of a station connected thereto, an operators linkcircuit connected with said line rendering it busy, a second link-circuit connected With said line, an operators manually operated ringing key associated with said link-circuit, and apparatus sensitive to the connection of said first link-circuit with said line to stop said key when freed manually, in non-ringing position and to. extend a signal.

7. A telephone exchange system including telephone lines, a plurality of stations connected to one of said lines, a link circuit aving a movable'. terminal connected to said one of said lines, a second link circuit having a movable terminal adapted for simultaneous connection to said line, apparatus associated with said'second link cirof current over said line when idle to selectively signal a substation thereon, and apparatus operated responsive to the connection of said first link circuit to prevent transmission of said'current and extend a signal when said second link circuit is connected to said line.

8. A telephone exchange system includingtelephone lines provided with terminals at the exchange, a plurality of substations connected to some circuit for connecting said lines adapted to be connected to said terminals, a polarized electro-magnet associated with said link circuit adapted for energization on connection made with aline, apparatus controlled thereby on connection made with an idle-line to establish a path for ringing current, apparatus controlled therebv on connection made with a busy line to prevent the establishment of a path for ringing current and to extend a altering the called line,

ones of said lines, a link signal, and means for establishing a-curlrent How to selectively signal a substation of an idle line.

9. A telephone exchange system includin'g telephone lines, a plurality of substa-- tions connected to some ones of said lines,

a'link circuit for connecting said lines, a

polarized electro-magnet associated With said link circuit adapted for energization on connection made `with a line', apparatus controlled thereby on connection ma'de with an idle line to establish a path for ringing current, apparatus controlled thereby on connection made `lwith a busy line-to prevent the establishment cfa path for ringing current and to extend a signal, means for establishing a current flow of predetermined character to selectively signal a substation of an idle line, and apparatus actuated on the vresponse of the called subscriber to terminate the How of signaling current.

'10, A telephone exchange system including a calling telephone line and a called telephone line, a plurality of stations con nected to said called line, multiple terminals of said lines, a. link circuit connected with the calling line, a calling terminal for said circuit ror-v connecting with a terminal of a polarized electro-magnet connected With said calling terminal adapted for energization on connection of said terminal with said line, a second link circonnected with .connected to alter the condition of its terminals to render them busy, signaling keys for said first link circuit for Aselectively signaling the stations of the called line, armature mechanism for said polarized electro-magnet, means for causing said mechanism to assume one position when connection is made with an idle line and a second position when connection is made with a busy line, apparatus operated when said mechanism assumes the first position to establish a connection to said calling terminal for the transmission of signaling, current, and apparatus operated when said mechanism assumes the second position to prevent the establishment of said connection, and to connect a source of signaling current with the callin'g line.

l1. A telephone exchange system including a` calling telephone line anda called telephone line, a plurality ot stations connected to said calledline, multiple terminals of said lines, a link circuit connected with the calling line, a calling terminal 'for said circuit for connecting with a terminal of the called line, a polarized electro-magnet connected with said calli'ngterminal connected with said called line and When so connected to alter the condition of its terminals to render them bus signaling keys for said iii-st link circuit for selectively signaling the stations of the called line, armature mechanism for said polarized electro-magnet, means for causing said mechanism to assume one position when connection is made with an idle line anda second position. when connection is made with a busy line, apparatus operated when said mechanism assumes the first position to establish a connection to said calling terminal for the transmission of signaling current, apparatus operated when said mechanism assumes the second position to prevent thel establishment o said connection, and to connect a source of signaling current with the calling line, and an electro-magnet actuated on a response at the called substation to terminate the flow of signaling current.

12. A telephone exchange system including a calling telephone line and a called telephone line, a plurality of stationsvconnected to said called line, multiple terminals of said lines, a link-circuit connected with the calling line, a calling terminal for said circuit for connecting with a terminal of the called line, a polarized electro-magnet connected with said calling terminal .adapted for ener- ,gization on connection of said terminal with said line, a second link circuit and terminals therefor adapted to be connected withv said called line and when so connected to alter the condition of its terminals to render them busy, signaling keys for said first link circuit for selectively signaling the stations of the called line, armature mechanism for said polarized electro-magnet, means for causing said mechanism to assume one position when connection is made with an idle line and a second position when connection is made with a busy line, an electro-magnet energized by said mechanism when caused to assume its first position to place said signaling keys in operative relation with said calling terminal, and a second electro-magnet adapted to be energized responsive to said mechanism when caused to assume its second position to prevent the placing ot' said signaling keys in said operative relation and to extend a busy signal to the station of the calling line.

13. A telephone exchange system includ-- ing a calling telephone line/and a called telephone line, a. plurality of stations connected to said calledline, multiple terminals of said lines, a link-circuit, connected with the calling line, a calling terminal for said circuit for connecting with a terminal of the called line, a polarized electro-magnet connected with said calling terminal adapted for energization on connection ot said terminal with said line` a second link-circuit and terminals therefor adapted to be connected with said called line and when so connected to alter the condition of its terminals to render them busy, signaling keys for said first, link circuit for selectively signaling the stations of the called line.I armature mechanism for said .polarized electro-magnet, means for causing said mechanism to assume one position when connection is made with an idle line and a second position when connection is made with a busy line, an electro-magnet energized by said mechanism when caused to assume its first position to place said signaling keys in operative relaelectro-magnet adapted to be energized responsive to sald mechanism when caused to vtion with said calling terminal, a second i assume its second position to preyent the placingof said signaling keys in said operative relation and to extend a busy signal to the station ofthe 'calling line, and an electro-magnet actuated on a response at the called station to place said signaling keys in operative relation with said calling terminals, wheieby the flow of signaling current over the called line is terminated.

14. In a telephone exchange system including .telephone lines, substations connected thereto, signals at the exchange adapted for display responsive tocurrents over said lines, multiple terminals associated with said lines and lilik-circuits for interconnecting said lines, adapted for connection with said terminals to render them busy, the combination with a link circuit of party line ringing mechanism therefor comprising a plurality of keys adapted for actuation by the operator, means sensitive to the electrical condition of the called line for holding an actuated key in a ringing position to signal a called substation when connection is made with said line, and apparatusfor automatically extending a busy signal to a calling substation when connection is made with a busy line.

15. In a telephone exchange system including telephone lines, substations connected thereto, signals at the exchange adapted for display responsive to' currents over said lines, multiple terminals associated with Said lines and link-circuits for inter-- connecting said lines, adapted for connection with said terminals to render them busy, the combination with a linkA circuit of party lineringing mechanism therefor comprising a plurality of keys adapted for actuation by the operator, means Yfor holding an actuated key in a ringing position to signal a called substation when connection is made with an idle line, an electro-magnet for said link circuit operated on the response at the called substation adapted when operated to cause an actuated key to leave the ringing position to assume an indicating position, and apparatus for automatically extending a busy signal to a calling substation when connection is made with a busy line.

16. In telephone exchange system including te ephone lines, substations connected thereto, signals at the exchange adapted for display responsive to currents over said lines, multiple terminals associated With said lines and link-circuits for interconnecting said lines, adapted for connection With key in a ringing position to signal a called substation when connection is made With an idle line, an electro-magnetfor said link circuit operated on the response at the called substation, adapted when operated to cause an actuated key to leave the ringing position to assume an indicating position, means for operating said electro-magnet When connection is made with a busy line, and apparatus for automatically extending a busy signal to a calling substation when connection is made With'a busy line.

17. A telephone system including a subscribers line, a link-circuit for connection therewith, a polarized relay for said circuit at the exchange, a terminal for said line at the exchange, means for controlling said relay over a circuitincluding a talking contact of said line terminal and switching devices efi'ective on operation of said relay to disconnectthe same from said contact.

18. A telephone system including a telephone line having a plurality of substations, a link-circuit for connection therewith, a plurality of ringing circuits adapted for connection With said-link-circuit for selectively ringing the stations of said line, multiple connection terminals of said line, a relay for said link-circuit operatedv over a circuit including a talking contact of a terminal of the line, and switching contacts controlled by said relay for determining the operative or inoperative relation of a ringing circuit With the line to selectively signal a station thereon. y

19. A telephone system including a telephone line, a plurality of stations connectedthereto, a source of signaling current, means for associating said source with said line to selectively signal a station thereof, a relay controlling' the connections of said source and sensitive to curren s over a' circuitincluding a\portion of the talking circuit ofl the line for determining the operative conv nection or disconnection of said source With said line, according to the idleor busy condition thereof.

p 20. A telephone system including a te ephone line, a plurality of stations conne ted thereto,y a source cf signaling curre t, means for associating said sourcel with s d line to selectively signal a station thereof, a relay for controlling the connections of said source to the line, and means for operating said relay .over a. circuit including. a portion of the talking circuit of the line, said'relay vbeing sensitive to the idle or busy condition of said line.

21. A telephone system including a sub-y scribers line, multiple terminals at the exchange therefor including talking contacts,

a link-circuit having an adjustable terminal including contacts for connection with said talking contacts, a plurality of stations connected With said line, and means f or connecting a source of signaling current with s a portion of said link-circuit to selectively signal a station of. said line, a test device connected to vsaid test terminal sensitive to the idle or busy condition of said line, means automatically controlled by said device responsive to the busy condition of said line to prevent the application of-said apparatus thereto, and responsive to the idle condition thereof to allowthe effective application of said apparatus, a circuit-changing device at the exchange for causing disconnection of said apparatus from the idle calledline, a

normal high resistance circuit at the substations of said line preventing the actuation of said circuit-changing device When Said apparatus is first connected thereto, and means controlled by the removal of a receiver at a substation to close a circuit of relatively low resistance to operate said circuit-changing device.

23. The combination With a subscribers telephone line having multiple terminals at the exchange, of an operators cord-circuit having a terminal for connection with said multiple terminals, a signal device associated With said cord-circuit, a polarized relay for controlling said signal' device, means for operating said relay over a circuit inL ycluding a contact of the connection terminal and a talking contact of a multiple terminal and electromagnetic means actuated responsive to said relay to open its circuit. y

24. A ,telephone system including telephone lines, a link-circuit to connect With called lines, automatic ringing and busy test means for said circuit responsive to connection of said circuit With a line, a plurality of ringing keys Ifor projecting signaling current of varying characters lover called isc tion of said circuit with a line,a plurality of ringing connections for said link-circuit, manually operable actuating devices, one for each said connection, a magnet common tov said devices for controlling the position of an operated device, and means for controlling said magnet.

26. A telephone system including telephone lines, a link-circuit to connect with A called lines, automatic ringing and busy test meansfor said circuit responsive to connectiod'of said circuit with a line, a plurality of ringing connections for said link-circuit, manually operable actuating devices, one for ,each said connection, and a magnet common to said devices for controlling the position of an operated device, said magnet being controllable responsive to current over the called line.

27. A telephone system including telephone lines, a link-.circuit to connect with lcalled lines, automatic ringing and busy test means for said circuit responsive to connection of said circuit with a line, a plurality of ringing keys for projecting signaling current of varying characters over called lilies, a common magnet for controlling an actuated one of said keys, and means for operating said magnet.

28. A telephone system including multiple terminal contacts, a link-circuit Jfor connection with said contacts, a plurality of ringing keys adapted to connect signaling current of diiiering characters with said linkcircuit, a magnet common to said keys for controlling the operative position of an actuated key, a circuit for said magnet, and means sensitive to the idle or busy condition of a contact connected with said link-circuit for determining the condition of said circuit. i

29. A telephone system including multiple terminal contacts, a link-circuit for connection with said contacts, a plurality of ringing keys adapted to connect signaling current of differing characters with said linkcircuit, a magnet common to said keys for controlling the operative position of an actuated key, a supervisory relay, and a manually operated switch adapted to change the connections ot' a contactA connected with said link-circuit whereby said relay is operated to control said magnet.

30. A telephone system including multiple terminal contacts, a link-circuit for connection with said contacts, 1 a plurality of ringing keysr adapted to connect signaling current of differing characters with said linkcircuit, a magnet common -to said keys for controlling the operative position of an actuated key, a circuit for said magnet, a supervisory relay for controlling said circuit, a manually operated switch adapted to change the connections of a contact connected with said link-circuit, said relay being responsive to such change to altery the electrical condition of said magnets circuit.

31. A telephone system including tele- 'phone lines, a link-circuit having a terminal for connection with called lines, a plurality of ringing keys controlling the ringing connections of said link-circuit, a magnet common to said keys to restore an operated one, a supervisory relay for controlling said magnet, and means controlled at the substation of a called line to operate actuating said magnet.

32. A telephone system including telephone lines, a link-circuit having a terminal for connectionwith called lines, a plurality of ringing keys controlling the ringing connections of said link-circuit, a magnet Colnmon to said keys, mechanical connections for said magnet serving to control any actuated key, a supervisory relay for controlling said magnet, and means controlled at the substation of a called line whereby said relay is energized for actuating said magnet- 33. A telephone system 'comprising a called party telephone line, a link circuit connected thereto, ringing keys for connecting ringing currents of different character to said line and link circuit,a`magnet common to said keys, a relay and source of direct current in bridge of said line and link said relay for circuit, a switch at the called substation of said line adapted to be closed to cause operation of said relay by said source, and circuit connections effective upon such operation whereby said magnet is operated to release anv actuated key.

.keys r A telephone system, including telephone lines, a link circuit to connect with a called one of said lines, ringing currents, manually operated keys for causing association of any one of said currents with said line. a busy signal, automatic apparatus differently operable according to the idle or busy condition of the called line whereby associating dif-` the selected ringing current is connected to said line if idle or the busy signal is connected to a strand of the link circuit if said p line is busy.

36. A telephone system, comprising subscribers7 lines terminating in multiply connected two contact jacks at the exchange, a link-circuit for establishing connection between the said contacts of calling and called lines, and means for automatically transmitting a busy signal to the calling party upon the connection of the link-circuit to a busyv change, a link circuit for establishing connection'between the said contacts of calling and called lines, and Iapparatus diilerently operable according to the .idle or busy con'- dition of the calledline to automatically connect ringing current to saidline or transmit a characteristic busy signal to the calling substation according to such idle or busy condition. I

39. A telephone' system comprising subscribers lines terminating in multiply connected two contact jacksA at the 'i exchange,

an operator controlled link vcircuit for in-A terchangeably establishing connections between said contacts of calling and called lines, and apparatus diiierently operable according to the idle or busy condition of the called line connected with to connect ringing current to said line or transmit a characteristic busy signal to the calling vsubstation according to such idle or'busy condition.

40. A telephone system comprising subscribers lines terminating inmultiply connected two contact jacks at 'the exchange, some of said lines having a plurality of sub stations connected therewith, a link circuit for establishing connection between said contacts of calling and called lines, ringing currents for selectively signaling such substations, means for associating any one of said currents with the link circuit, and apparatus differently operable according to the idle or busy condition of the called line to connect the associated ringing current t`o said line or transmit a characteristic vbusy signal to the calling line according to 'such idle or busy condition.

41. A telephone system comprising subscribers lines 'terminating in multiply connected two contact-jacks lat the exchange, a link circuit for establishing connections be tween the said contacts of calling and called lines, signals for each of said line circuits, apparatus ,operated responsive to connection made with' an idle line to selectively operate one of said signals, and automatic means for transmitting a busy signal upon con# nection to a busy line.

42. A telephone system including party i lines, a link circuit having connecting plugs for connection thereto, means for selectively ringing a desired substation on one of said lines, said means being ineffective if said line is busy upon connection made therewith, and means responsive to the busy condition of said called line to extend a busy signal if said means is ineffective.

43. A telephone system comprising subscribers lines terminating in multiply connected two-contact jacks at the exchange, a

link circuit for establishing connection between the said contacts of calling and called lines, signals for each of said line circuits,

apparatus for selectively operating said signals, said apparatus being responsive to connection made with an idle line, and automatic means for transmitting a busy signal upon connection to a busyline.

In witness whereof, I hereunto subscribe my name this 17th day of March, 1906.

ALFREDv H. DYSON. Witnesses: n

H. C. OLMsTEAD, L. O. KELLOGG.

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