US1488586A - Senderless automatic telephone satellite system - Google Patents

Description

April 1 1924.

G. DEAKIN SENDERLESS AUTOMATC TELEPHONE STELLTTE SYSTEM 4 Sheets-Sheet l Filed Sept. 1, 1921 4 SheetsjSheet 2 G. DEKIN Filed Sept. 1 1921 SENDERLESS AUTOMATIC TELEPHONE SATELLITE SYSTEM RN. .n

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SENDERLESS AUTOMATIC TELEPHONE SATELLITE SSTEM Filed-Sept. l. 1921 4 Sheets-$heet 5 v fbv 1 G. DEAKIN SENDERLESS AUTOMATIC TELEPHONE STELL-TE SYSTEM Filed Sept. 1, 1921 4 Sheets-Sheet 4 H+ M. h

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WVM/0f Gera/d Ufa/rm, .by MaK/#ijf Patented Apr. l, 1924.

SES TENT OFFICE.

GERALD DEAKIN, OF ANTWERP, BELG-TUM, ASSIGNOR TO 'WESTERN ELECTRIC COM PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SENDERLESS AUTOMATIC 'TELEPHONIE SATELLTE SYSTEM.

Application filed September l, 19211. Serial No. 497,474.

(GRANTED UNDER THE PROVSIOITS THE ACT GF MARCH 3, 1921, 41 STAT. L., 1313.)

T @ZZ whom t may concer/n. f

Be it known that l, (zlninxne DnAxiN, a citizen ot the United States', residing in Antwerp, in the Kingdom of Belgium, have invented certain new and useful improvements in Senderless Automatic rlelephone Satellite Systems, for which my legal representatives have iiled application in England August 1919, 1iPatent No. 153,407, and of which the following is a full7 clear, concise, and exact description.

This invention relates to telephone exchange systems and particularly to systems in which there is provided a manual main exchange and a subsidiary exchange, calls being extended between the twoexchanges by automatically operable switching mechalllSll'l.

In its broadest aspects this invention provides an arrangement by which the extension or calls through the main exchange isy eiected in the saine way for calls also-passing through the subsidiary exchange as jfor calls from subscribers lines which terminate directly at the main exchange. The work of the attendants at the manual exchange is, therefore7 simplified and the expense of handling calls involving the subsidiary exchange is reduced in comparison with what would be the case it a special operator or a special manually operable means were required at the main exchange.

According to a specific feature of the invention. there is, associated with each set of jacks in the manual switch oard at the mainv exchange over which connections to the subscribers lines terminating in the main exchange are made by the manual operator, a similar set ot jacks over which the manual operator similarly extends connections for subscribers7 lines terminating in the subsidiary exchange.

According to further Jfeatures of the invention, means are provided whereby the automatic mechanism between the main exchange and the subsidiary exchange effects the operation of coin collecting and receiving mechanism at prepayment subscribers7 stations associated with asubsidiary exchange, or the operation of metering devices individual to subscribers lines terminating at the subsidiary exchange.

According to another feature of the invention, the extension of calls from the manual exchange to a wanted subscribers line terminating at the subsidiary exchange is automatically v eiiected in response to the completionof the manual extension of acall through the main exchange.

A further feature of the invention and one relating to the last named feature, is the provision of a selector and registering apparatus for controlling the operation of' said selector in accordance with the designation of the desired line, means being pro-vided by which operation of said registering apparatus is automatically effected in response to the connection .of a calling line to said switching mechanism. f

il still further feature of the invention is the provision, in a telephone exchange system, in which calls are automatically ex tended over a multi-position switch in certain positions ofwhich ringing current may` he sent to the called subscribers line, ,of means for preventing or permitting the application of such current according to the class of calls being extended.

Other features' and advantages ofthe invention will be apparent from the subjoined detailed specification and appended claims 'read in connection with the accompanying drawings in which Fig. l shows an automatic switching apparatus for connecting a calling subscribers line terminating at the subsidiary or satellite exchange to a junctionline leading to the manual main exchange; Figs. 2 and 3 show manual operators cord circuits for use at the manual main exchange; Fig. 4 illustrates a sending switch arrangeinent for extending a call from the manualexchange to an automatic subsidiary exchange; Fig. 5 shows a corresponding. receiving switch circuit arrangement by which a call is ext-ended at the subsidiary exchange to the calling subscribers line; andr Fig. 6 illustrates a modified arrangement of a subscribers line designed for prepayment service, the arrangement in Fig. l being designedfor metering an incoming call.

Vihen Fig. Fig. l, Fig. 4l to the right of Fig. 2,1and Fig. 5 to the right of Fig. 4, there will be exhibitedr the combined circuitarrangement by which a call may be extended from a sub- 2 is arranged to the right of.

scribers line terminating at an automatic exchange, subsidiary to the manual main exchange, to another subscribers line terminating at such a subsidiary exchange; the two subscribers lines may terminate at the same subsidiary exchange or at different exchanges. Moreover, the cord circuit shown in F ig. 3 may also be used, without any change in the manual operators procedure, for extending an incoming call from a satellite subsidiary exchange to an ordinary subscribers line terminating in the manual main exchange, or for extending a call from such a subscribers line to the switching mechanism that will automatically further extend the call to a desired subscribers line terminating at the satellite exchange.

j The manual main exchange and the automatic subsidiary exchange are connected by a group of junction lines, only one of which is shown, over any of which a call may be extended from the subsidiary exchange to the manual main exchange and also by another group of junction lines, only one of which is shown, over each of which calls may be extended in the opposite direction. lVhen a subscriber whose line terminates in a subsidiary exchange lifts his receiver from Vits support, a group of line finders at the subsidiary exchange are set in operation to connect an idle outgoing junction line, to the subscribers line. ln Fig. 1 a first and a second line finder of well known types, are shown, but in small exchanges it may be sufiicient to use only first line finders. vWhen a connection has been made, the call appears on the manual switchboard at the main exchange and is handled in the same manner as if it were from a subscriber whose line leads directly to the manual main exchange.

In extending a call to a subscriber served by the subsidiary exchange, the manual operator proceeds the same way as in the case of a call for aI subscriber whose line terminates in the manual exchange, i. by inserting the callingv plug of her cord in a multiple jack designated by the. number of the desired line. This operation causes the automatic setting of registering apparatus in accordance with the designation of the desired line, and this apparatus thereupon assumes control of selectivelyy operable switching mechanism which extends the call to the desired subscribers line in the same general manner as is done in the well-known systems using key or dial controlled registering apparatus.

The distinctive features of the invention are more explicitly set forth in the following tacts on F ig. 4 are part of sequence switch 400, except those included in the broken line rert-angles enclosing distributing sequence switch 450, tens register 480 and units register 490, and which are parts of their respective switches and the sequence switch contacts shown on Fig. 5 are part of sequence switch 500. lVhen a calling subscriber whose line terminates in such exchange removes his receiver from its hook, the line relay 103 is energized in the well known manner and places potential upon the terminal 105 and also energizes the brush carriage magnets of the various idle first line finders accessible from the calling line and thus effects the connection "of one of said first line finders to the terminal of the calling line in the well known manner. When this connection has been effected, common starting relay is energized in a circuit over the front contact and armatura-i of test relay 108 and back contact and armature of relay 106 to grounded battery, a potential at the same time being placed on terminal 115. A circuit is closed from ground, ar'- mature and front Contact of starting relay 109, seque-nce switch contact 121 top, of sequence switch 120 of each idle second line finder, armature and back Contact of relay 122, sequence switch contact 123 bottom, brush carriage power magnet 140 to grounded battery. The brush carriages of the idle second line finder switches hunt for the terminals of the first line finder and these having been found by one of the second line finders, a circuit is established from battery` arma-ture and back contact of relay 100, armature and front Contact. of relay 108, terminal 115, right-hand high resistance winding of relay 119, sequence switch Contact 124 topi to ground. Relay l119 operates and makes the circuit with which it is associated busy by shunting its associated high resistance winding over its front contact to ground at interrupter 142. lVhen the brushes center themselves, this ground is removed and relay 122 is energized thereby opening at its baci: contact the circuit of power magnet 140 and completing a circ-uit from ground, armature and front contact of relay 109, sequence switch contact 121 top, armature and front contact of relay 122, sequence switch contact 133 bottom and sequence switch 120 to grounded battery and in parallel therewith over sequence switch contact 132 bottom and brush carriage holding magnet 141 to grounded battery. Sequence switch 120 advances to position 5. In position 2 of sequence switch 120; cutoff relay 101 and relay 106 are energized in a circuit completed over terminal 114, lefthand armature and Vback contact 'of relay 126, sequence switch contact 127 bottoni to ground, but the service meter 102 is not op erated under this condition, since it is deresase signed to operate only when double the normal exchange potential is applied.

Should the brushes of two 'line finders reach the terminals 114 simultaneously, the test relays ot both line finders will release when the circuits tor the high resistance windings of relays 119 are opened at sequence switch contacts 124 top in position 2 ofthe sequence switches 1.20. The consequent release of each relay 122 closes a circuit from ground, sequence switch contact 121 bottom, armature and back contact of relay 122 and sequence switch contact 123 top Jfor the energization of relay 126 which locks up over its .front contact and sequence switch contact 128. The test circuit towards the second line iinder is in each case opened at the left-hand Contact of relay 126 so that the line relay remains energized, thereby causing the terminal 114 to be selected by solne other line finder. When sequence switch 120 reaches position 5, a circuit is established from ground, outer right-hand armature and back contact ot relay 144, leftback contact and armature of relay 136, sequence switch contact 133 top, sequence switch 120 to grounded battery. Sequence switch 120 advances to position 9 and then to position 12 and from there to position 18, a circuit being established in position 9 'from ground, armature and back contact ot relay 138, sequence switch contact 135 and sequence switch 120 to grounded battery, and a circuit being established in position 12 from ground, armature and back contact of relay 144, outer armature and back contact of relay 136, sequence switch contact 133 top and sequence switch 120 to grounded battery. Sequence switch 120 remains in position 18 until another second line iinder leaves position 1 atwhich time a circuit is established from ground at the other second line finder sequence switch contact 124 bottom to sequence switch contact 132 top of the first mentioned line linder, sequence switch magnet 120 to grounded battery.

A single second line iindeiqhaving made connection with the calling line, the cutolll relay 101 having been operated as above described, removes ground from the tip side of the line and disconnects the line relay 103 from the ring side of the line. Relay 103 deenergizes and causes the deenergization ot the test relays 107 and 103. Relay 106 having been energized at the same time as relay 101 opens at its back contact, the circuit o't common starting relay 109 and removes the test potential from terminal 115` and thereby causes the release of test relays 119 and 122. lVhen sequence switch 120 reaches position 2, a circuit is established from ground, sequence switch contact 128, armature and back contact of relay 126 and relay 129 to grounded battery. Relay 129 operates and closes a transmission circuit yin position 5.

from ground, one winding of repeating coil 150, upper back contact and armature ot relay y130, sequence switch contact 131 bottom, upper armature an-d Yliront contact of rela-y 129 to the upper conductor or tip side oi the line, the calling subscribers telephone set, lower `conductor or ringside of the line, lower armature and front contact ot relay 129, lower armature and back contact of relay 130, winding of the repeating coil, relay 137 to grounded battery. Relay 137- operates and at its front contact closes the energizing circuit for relay 144. At its right-hand front contact relay 144 shortcircuits the high resistance winding or rela i 145 and opening its back contact prevents the completion over sequence switch contact 133 top ot an energizing circuit for sequence switch 120 which therefore remains In position 5 of sequence switch 120, a circuit is established from ground, sequence switch contact 146 top, inner armature and back contact of relay 201 and winding of relay 202 to grounded battery. Relay 202 operates and causes lamp 203 to burn. The operator answers with an idle answering plug 205 and establishes a circuit from ground, one leg or" winding of cord circuit repeating coil 250, tip of plug 205, jack 204, one leg of the repeating coil 150, low resistance winding of relay 145, lett-hand inner front contact and armature oig relay 144, other leg of the repeating coil 150, sequence switch contact 147 bottom to grounded battery. Relay 145 operates and closes the energizing circuit of relay 136, which at its right-hand back 'contact disconnects polarized relay 138 from the tip side of the line, at the same time a circuit is established Ptrom ground, sequence switch contact 139 bottom, left-hand front contact and armature ot relay 136 and sequence switch contact 133 top for the energization ot sequence switch 120 which advances to position 8. Relay 201 is also energized in a circuit over the sleeves of jack 204 and plug 205 and opens at its bac-lr contact the circuit of relay 202 and consequently extinguishes the lamp 203.

The short-circuiting of the high resistance winding of relay 145 by relay 144 as described above, causes the supervisory relay 212 of the cord circuit to operate and to short-circuit and extinguish supervisory lamp 206, which was energized over the sleeves of plug 205 and jack 204. The junction circuit and the cord circuit both remain in the condition just described during conversation provided combination coin collec tion and service meter key 214 or coin return hey 215 is not thrown.

As long as relay 145 remains energized, the release of the connection is under the control ot the operator. The subscriber may signal in the usual manner by intermitwinding of relay 145 is there-tore removed and the supervisory relay 212 in the operators cord circuit releases its armature and thus causes supervisory lamp 206 to burn. The operator removes plug 205 from the jack 204, thereby causing the release of relay 145 and consequently of relay A circuit is thereby established trom ground, outer armature and back contact of relay 144, left-hand ari'nature and back contact o1 f relay 136 and sequence switch contact 133 top for the energization ot sequence switch 120 which advances to position 9, in which position a circuit is closed trom ground, armature and back contact ot' polarized relay 1,38 and sequence switch contact 135 for the Nfurther energization of sequence switch L20 which advances over positions 10 and 11 into position 12. In this position a circuit is closed from ground, outer armature and back contact of relay 144, lett-hand back contact and armature oi relay 136 and sequence switch contact 133 top, tor the energization ot' sequence switch 120 which advances to position 18. ln position 18 of sequence switch 120 the circuit ot relavs 106 and 101 is opened at sequence switch contact 127 and the circuit of relay 12S) is opened at sequence switch contact 128; the callimy subscribers line is therefore released and tue junction circuit is opened at the liront contacts ot relay 12S). Sequence switch 120 ren'iains in position 18 until an energizing circuit Athere-'tor over sequence switch contact 132 top is completed over sequence switch Contact 124 bottom ol another sequence switch 120 in passing to position 5.

For 1 i'i- ,1Jziy'irieiit service a subscribei"s station may be equipped with a coin operable device oit well known construction indicated diagrammatically in Figure 6, the polarized relay 52 being responsive to relatively high voltage current of negative polarity to release the coin 53 and responsive to relatively high voltage currentof positive polarity to cause the deposit of the coin in the collection receptacle.

If a call has originated at a prepayment station and it the coin has not been co-llected, as sequence switch 120 passes positions 13 to 17 inclusive, a circuit is established from the negative pole of high voltage battery 190, sequence switch Contact 131 top, upper Contact and armature of relay 129, upper or tip side ot the line, winding ot the polarized magnet 52 of the coin de.- vice, coin 53, to ground and the coin device is operated to effect the release oli' the coin.

As no changes in the method of operation are to be made at the central office when handling calls coming in through the satellite exchange the coin release key 215 of the operators cord circuit will be' thrown whenever the coin is to be released by the operator, and this vmay be done either during or at the end of a conversation. It key 215 is thrown during conversation the line circuit is open at contacts of the key and relays 145 and 136 are therefore deenergized, but as the polarized relay 138 does not operate when current is supplied from the negative pole ot the battery 210 the sequence switch 120 remains in position 8. Should the key 215 be thrown at tie end of the conversation after the calling subscriber has hung up, relays 145 and 136 both release, and sequence switch 120 is drive-11 to position 18 in exactly the same manner as though the calling plug had been removed fromv the answering jack; in which case the coin is released when the sequence s y'itch 120 passes through positions 13 to 17 as described above. Y

To collect the coin, the operator throws coin collector key 214 of her cord, plug 205 not having been withdrawn from ack 204, and thereby supplies current from the positive pole of the high voltage coin collector battery 210 over the tip side of the line of the junction circuit and at the same time opens the ring side of the line. Relay 145 is released and in turn releases relay 130. It' the calling subscriber has not hung up, relay 144 will remain energized. A circuit is now established from the positive pole of coin collector battery 210, relay 216, outer contact ot key 214, inner Contact ot key 215, tip of plug 205, tip of jack 204, right-hand back contact and armature of relay A30, winding ot polarized relay 138 and sequence switch contact 139 top to ground. Polarized relay 138 is energized and at its 'front (or ripper) contact closes a circuit for the energization ot relay 130 and'in parallel therewith a circuit over the. right-hand back contact and armature and winding ot relay 151, sequence switch Contact 147 top to grounded battery. Relay 130 pulls up its armatures and opens the ring side of the line and at its upper front Contact applies the positive side of the high voltage lbattery 190 to the tip side of the line, thereby effecting in a well known manner, the deposit of the coin at the subscribers station. This circuit is maintained as long as key 214 remains thrown, the circuit of lamp 217 being completed at the front contact -of relay 216. Relay 151 locks up over its righthand armature and front contact. As the Lacasse circuit of relay 137 is opened at the lower back contact of relay 130, the former relay is deenergized and releases relay 144 and the circuit is established from ground, outer armature and back contact of relay 144, left-hand back Contact and armature of relay 136 and sequence switch contact 133 top for the energization of sequence switch 120 which advances to position 9. Nhenthe operator restores key 214, the junction circuit is again closed and relays 212 and 145, and Consequently relay 136, are again energized; polarized relay 138 and relay 130 are released and relay 144 is reencrgized, the high resistance winding of relay 145 being short-circuited in consequence. By` the release of relay 138 a circuit is established over its armature and back contact, and sequence switch contact 135 for the energization of sequence switch 120 which advances to position 12. To check the operation of the coin machine the operator may throw the key 21'4 a second time. Relay 145 is thereby deenergized but the circuit of polarized relay 13S being opened at sequence switch contact 139 top, this relay does not operate and pilot lamp 217 does not burn. T his indicates to the operator that the coin has been taken. The closure of the calling line, since it has been assumed that the calling subscriber has not hung up, maintains relay 1.37 and consequently relay V144 energized and sequence switch 120 therefore remains in position 12 for the remainder of the conversation. `When the subscriber hangs up and the operator disconnects sequence switch 120 advances to position 18 as previously described.

To prepare the circuit for metering, in the case of subscribers stations using a metered service, the operator throws the combined coin collector and service meter key 215 and energize-s relay 151 as described above. Metering does not take place during conversations but at the end ofaconversation when the circuit is released, a meter'- ing potential is supplied in positions 13 to 17 over a circuit from the positive pole of the battery 149, left-hand front contact and armature of relay 151, sequence switch Contact 127 top, armature and back contact of relay terminal 114, relay 106, terminal 104, service meter 102 and cutolii' relay 161 in parallel, to the negative pole of the grounded battery. The increased current thus furnished, causes the operation ofthe service meter 102. llVhen the sequence switch' 120 reaches position 18, sequence switch contacts v147 and 127 are open and the relays restored to normal.

In the extension through the manual main exchange of a call for a subscribers line terminating in the subsidiary automatic exchange, it is immaterial whether or not ythe operator lrnows that the desired party is a subscriber to a satellite exchange. Having learned the number of the desired line yfrom the calling subscriber, she tests the corresponding multiple jack 254 in the usual way and if the line is found busy, informs the calling subscriber to that edect. 1f the wanted line is free, the operator inserts her calling plug into the jack 254. She may depress her ringing key, but such action will have no effect on the wanted line. When the operator inserts her calling plug into the multiple jack, relay 265 is energized and the supervisory lamp 256 in the cord circuit is illuminated. Energization of relay 265 places test potential on the proper level of all of the tens registers 480 in a circuit from grounded battery, left-hand armature and front contact of relay 265, lower armature and back contact of cutoff relay 266 to level 487 ofv tens register 480, it being assumed that the multiple jack is connected to a set of fixed terminals 443, 444 etc., in

the sixth level of the arc of the sendingswitch. A test potential is also placed on the test terminal 443, the circuit being from grounded battery, winding of cutoff relay 266, right-hand inner 'front contact and armature of relay 265 to test terminal 443.

In the arrangement shown, the terminal bank of each sending switch contains two hundred sets of fixed terminals, 443, 444, etc., arranged in ten levels of twenty sets each, each set being inultipled through the banks of the various sending switches. rllhe terminals in a given level consist of those corresponding to lines whose designations contain a given tens digit, the terminals in each level being arranged according to the combination of the hundreds and units digit in the designation of the corresponding subscriber-s line. rllhe terminal bank of the selector at the receiving switch (Fig. 5) is similarly arranged.

By means of the common distributing sequence switch 450 the several sending switches are brought into service one at a time. As soon as an active sending sequence switch 400 reaches position 5, the distributing sequence switch 450 immediately searches for another idle sending switch circuit aud, when one is found, puts it into service. A circuit from ground over sequence. switch contact 465, bottoi'i'i of sequence switch 400 and contacts 452, 453, etc., of distributing sequence switch 450 prevents the latter' from stopping on a busy' sending switch circuit. i

Assun'iing that the sending switch Shown in Fig. 4 is idle and is in position 1, (although it may come to rest in any of the idle positions 1 to 4) relay 265 at its outer righthand armature and front contact will close a circuit from ground over the upper armature and back contact of relay 266, contact 457 top of distributing sequence Isti/itch v450,

llO

contact 4.08 bottoni et sequence switch 400, relay 423, sequence switch contact 422 top to grounded battery. Relay 428 operates and closes a circuit from ground over its ,armature and front contact, sequence switch contact 418 bottom, sequence switch 400 to grounded battery, and sequence switch 400 advances to position 3. The circuit of the trip Vspindle magnet 430 is closed from ground, rumatnre and 'iront contact of relay 428, sequence switch contact 417 top, armature and back contact of relay 407, sequence switch contact 411 top, and trip spindle magnet 430 to grounded battery.

As the trip spindle is advanced from its position of rest to first position and afterwards from the first position to the second position and so on in the well known inanner, a circuit is intermittently established from ground at the upper contact spring of interrupter 435, sequence switch contact 421 bottom, to the junction point of the differential windings ot relay 495 and trom there in one direction through the high resistance right-hand winding oi relay 495 and retardation coil to grounded battery and in the other direction through the lett-hand low resistance winding, armature and back contact ot relay 495, sequence switch contact 415 bottoni and tens register 480 to grounded battery. Register 480 advances 'from position 1 to position 2 and at its local contact 481 grounds the back contact of relay 495 thereby unbalancing said relay and causing it to operate, while the ground at local contact 481 sends the tens register 480 to position 2. The ground at the upper contact of the interrupter 435 keeps the relay 495 energized until the trip spindle reaches its next position and the ground at the local Contact 481 having been removed, when. the tens register reaches its second position, relay 495 is deenergized. This sequence oi operations continues until the tens register is stepped into a position corresponding to the tens digit oi the designation of the desired line, i. e., 6, in which position a circuit is established from battery, left-hand armature and front contact ot relay 265, lower armature and back contact of relay 266, contact 487 bottom ot tens register 480, sequence switch con-tact 402 bottoni, lefthand high resistance winding oit' relay 406 and sequence switch contact 405 top to gro-und. Relay 406 operates and locks up in a circuit over its rightehand low resistance winding and its front contact and armature and` the winding of relay 407 to ground. Relay 407 operates and at its back contact opens the circuit of trip spindle magnet 430 and in place thereof, over its iront contact and by sequence switch contacts 417 top and 418 top, closes a circuit for sequence switch 400. The trip spindle is therefore arrested and sequence-switch 400 goes to position ll/Then trip spindle is brought completely to the selected position, relay 412 is released by the opening of the upper contact of interrupter 435 and opens the alternative energizing circuit of trip spindle 430. Then sequence switch 400 passes trom position 3 to position 4, the circuits of the test relays 406 and 407 are opened at the sequence switch contact 402 bottom and these relays therefore release.

In position 4 of sequence switch 400 the circuit of the brush carriage magnet 440 is closed over sequence switch cont-act 411 loottom, back contact and armature ot relay 407 and sequence switch contact 417 top to ground. The proper set of brushes i. e., i-n this case the sixth set, are tripped in the well known manner and commence the search for the terminals ot' the calling line. As the brush carriage advances the units register 490 is advanced in substantially the same manner as described above in connection with the tens register 480, an interrupter circuit being closed from ground, upper contact oi interrupter 44.5, sequence switch contact 421 top, common junction point ot the windings of differential relay 495 and from there in one direction through the high resistance winding of relay 495 and retardation coil to grounded battery and in the other direct-ion through the low resistance winding, armature and back contact of relay 495, sequence switch Contact 415 top and units register 490 to grounded battery. The units register is advanced step-by-step in the same way as was the tens register. Then the brushes reach the terminals connected to the multiple jack into which the operator has inserted her calling plug, a circuit is established from grounded battery, winding of cutol'f relay 266, inner front contact and armature ot' relay 265, terminal 443, brush, sequence switch contact 402 top, lett-hand high resistance winding ot test relay 406 and sequence switch contact 405 top to ground. Relay 406 operates and closes the circuit of its low resist ance winding over its front contact to ground at the contact on the toothed rack ot interrupter 445. Then the brushes center themselves, this last named ground is removed and the circuit of test relay 406 continues through the winding of test relay 407 to ground. rlfhe latter relay operates and opens the circuit ot the power magnet 440 at its back contact, and over its front contact, sequence switch cont-act 417 top, establishes a circuit tor sequence switch 400 which advances to position 5. Holding magnet 441 is energized with sequence switch 400 over a circuit closed at sequence switch contact 416 bottom in position 4 and the brushes are thus brought to rest. Test relays 406 and 407 remain energized during the remainder of the connection, the low llO resistance windings making the multiple jack terminals busy to such other sending witches as may later hunt over the sixth evel.

It will be noted that the register sequence switch 490 has twenty positions, i. e., two positions for each unit from 0 to 9 inclusive; one of these two positions corresponds to the first hundreds and the other to the second hundreds into which the designations of the subscribers lines are grouped.l The register 490 therefore registers the hundreds as well as the units.

Cutoi' relay 266 having been energized in series with relays 406 and 407 removes the test potential from the tens register 480 and opens the common starting circuit to the distributing sequence switch 420. The send ing switch is now in direct connection with the multiple jack and the tensk and units registers 480 and 490 are set to positions corresponding to the number ot the desired line.

When sequence switch 400 reaches position 5, a circuit is established from gro-und at the receiving switch Fig. 5, sequence switch contact 502 bottom of sequence switch 500, conductor 461 of the trunk, sequence switch contact 424 bottom, at the sending switch (Fig. 4) back contact and armature of relay 425, relay 423, sequence switch contact 403 top, conductor 462 of the trunk to sequence switch contact 501 bottom, at the receiving switch and relay 506 to grounded batterygrelays 423 and 506 operate in series, sequence switch 400 is energized over a circuit from ground, armature and front contact of relay 423 and sequence switch contact 418 bottom and advances to position 6. Sequence switch 500 of the receiving switch is energized in a circuit from ground, armature and front contact of relay 506 and sequence switch contact 542 bottom and advances to position 2. A circuit for the trip spindle 520 of the receiving switch is established from ground, armature and front` contact of relay 506, sequence switch contact 507 bottom and trip spindle magnet 520 to ground. The receiving switch trip spindle 520 advances and as it travels from one position to the next its interrupter 525 momentarily closes its upper contact and, over sequence switch contact 503 bottom, short-circuits thc rela-y 423 which deenergizes, while relay 506 remains energized. A circuit is established from ground, armature and back contact of relay 423, sequence switch Contact 410, sequence switch contact 421 top, common junction point of the windings of differential relay 495 and from there in one direction over the right-hand high resistance winding ot relay 495 to grounded battery, and in the other direction over the left-hand low resistance winding; armature and back contact of relay 495, sequence established from ground, armature and back contact of relay 423, sequence switch contact 419 bottom, equence switch contact 421 top, left low resistance winding of relay 495 sequence switch contact 413 bottom, register sequence switch contact 482 top, sequenceswitch contact 427 top and relay 425 to grounded battery.` A parallel circuit is established over sequence switch contact 426 top for the energization of sequence switch 400 which advances to position 7. Relay 25 attracts its armature and at its back contact interrupts the fundamental circuit, thus causing the release of relay 506 as soon as the upper contact of interrupted 525 is opened; sequence switch 500 is energized in a circuit over the armature and back contact of relay 506 and sequence switch contact 541 bottoni and advances to position 5. When sequence switch 400 has reached position 7, its contact 427 is opened and the relay 425 is deenergized so that the fundamental circuit is again closed at its back contact.

The closure of the Jfundamental circuit causes the energizatlon of relay 423 as before kdescribed and a circuit is established from kfor the energization of sequence switch 400,

which advances to position 8. Relay 506 is energized, and as soon as sequence switch 500 reaches position 5 closes at its front contact a circuit over the sequence switch contact 536 for the energization of brush carriage magnet 530. The' brush carriage advances and the proper set of brushes, in this case the fourth set, are tripped and moved over the corresponding level of the selector bank. As the brushes advance to test each set ot' contacts in the fourth level, relay 423 is short-circuited over the upper contact of interrupter 535 and sequence switch contact 503 bottom; each time it is short-circuited relay 423 deenergizes and closes an energizing circuit for the units register over sequence switch contacts 419 bottoni, top, lciitelland winding, armature, and back contact ot relay 495, sequence switch contact 414 bottom, and register contact 492 bottom, and steps the units register to its normal position, i. e., position 1 in exactly the same manner as it previously returned the tens register to its normal position. When the units registerl reaches position 1, rela;7 425 I is likewise again energized and opens a fundamental circuit, thus causing the release of relays 423 and 506. At the front contact of relay 506 the energizing circuit for the brush carriage 530 is broken and the brush carriagecomes to rest. Sequence switch 500 is energized in a circuit from ground, armature and back contact of relay 506 and sequence switch contact 541 bottom and advances towards position 10. In a parallel with sequence switch 500, holding magnet 531 is energized in a circuit over the sequence switch contact 532 bottom and facilitates stopping the brush carriage on the terminals of the desired line. ln parallel with relay 425 sequence switch 400 is energized in a circuit over sequence switch contact 426 and advances to position 9.

As sequence switch 500 passes position 6, a circuit is established from ground, sequence switch contact 559 top, left-hand high resistance winding of test relay 556, brush 560, terminal 561 of the desired line, cutoff relay 565 and service meter relay 566 in parallel to grounded battery. If the wanted line is busy, relay 556 will not receive sufficient current to operate and sequence switch 500 having reached position 10, the circuit will remain as described until the connection is released. A circuit is closed from ground, common busy tone transformer 546, interrupter 547, sequence switch Contact 548 bottom, one winding of repeating coil 510, supervisory relay 540 to grounded battery and relay 540 operates intermittently as determined by interrupter 547. The other side of the trunk circuit is grounded at sequence switch contact 553 top, to reduce inductive disturbances. As will be described later on, the sending switch goes to the talking position so that the busy tone and busy flash are passed back to the manual operator and the busy tone to the calling subscriber. The flash is given by intermittently opening the trunk circuit at relay 537 which is controlled by relay 540.

Sequence switch 400 of the sending switch will have reached position 13 by the time sequence switch 500 has reached position 9 and a circuit is there established from ground at the receivingswitch, relay 539, right-hand armature and back contact of relay 537, one winding of repeating coil 510, sequence switch contact 502 top, conductor 461 0f the trunk, sequence switch contact 424 top of sequence switch 400, one winding of repeating coil 470, back contact and armature of relay 410, supervisory relay 409, a second winding of the repeating coil 470, conductor 462 of the trunk, sequence switch contact 501 top of the receiving switch, winding of repeating coil 510, left-hand armature and back contact of relay 537, relay 538 to grounded battery. Relays 538, 539 and 409 are energized. At the back contact of relay 409 the path for direct current towards thel calling cord circuit is opened Lacasse thereby causing the calling supervisory lainp r256 in the operators cord circuit to remain burning. The energization of relay 538 causes sequence switch 500 to remain in position 10 as its energizing circuit by way of sequence switch contact 541 top is opened at the back contact of relay 538.

If the wanted line is idle, relay 556 is en ergized over its high resistance winding as sequence switch 500 passes position 6, as above described, and provides a holding circuit for itself over its right-hand low resistance winding, front contact and armature, relay 557 and sequence switch contact 558; relay 557 is energized. Cutoff relay 565 .is also energized, in series with the test relays 556 and 557 but the service meter 566 is not energized since it is designed to opere ate only on double the normal exchange potcntial. Sequence switch 400 is energized in a circuit over sequence switch contact 417 bottom, armature and front contact of relay 407 and sequence switch contact 418 and advances to position 13. In positions 10 to 12 of sequence switch 400 a circuit is established from battery of the calling cord circuit to the ring of the calling plug 255, terminal 444, sequence switch contact 404 top and re lay 410 to ground. Asr relay 410 is a inarginal relay, it does not operate under these conditions. The junction circuit towards the receiving switch therefore remains open at sequence switch 424 top in positions 9 to 12 of sequence switch 400. At the moment the fundamental circuit is opened for the second time when the units register reaches position 1, as described above, sequence switch 400 is in position 8 and sequence switch 500 is in position 5, therefore sequence switch 500 passes position 7 before the junction circuit is again closed by the sequence switch 400 in position 13. Relay 545 is therefore not energized on local connections.

On a successful local connection sequence switch 500 goes directly from position 5 to 12 since in positions 10 and 11 a circuit is closed from ground, armature and front contact of relay 557, sequence switch contact 503 top, relay 506 to grounded battery, and relay 506 attracting its armature closes a circuit over sequence switch Contact 542 for the energization of sequence switch 500. Relay 506 is dcenergized in position 12 by the opening of sequence switch contact 503.

When sequence switch 500 reaches position 12, superimposed ringing current is supplied to the desired line in a circuit from battery, winding of relay 549, sequence switch contact 550, lower back contact and armature of relay 552, the wanted line, upper armature and back contact of relay 552, righthand armature and back contact of relay 545 and sequence switch contact 543 to the ringing'v generator; When the interrupt- :i ,ceases er 505 closes the circuit ci relay 506 over sequence switch contact 504 bottoni, the relay is energized and over its armature and iront contact completes a circuit through sequence switch contact 5&2 bottom, for the energization ot sequence switch 500 and therefore moves from position l2 to position 13 and vthen 'to position le; the initial ringing period is therefore trom l to 2 seconds depending upon the position ot the interruptor 505 when sequence switch 500 reaches position l2. ln position 'lll of sequence switch 500, the ringing circuit is transferred at sequence switch contact 543 bottoni to the machine ringing interruptor so that the call bell at the wanted subscribers station is rung at intervals until the subscriber answers and the connection is released.

7il/lien the called subscriber answers, ringing cutoll' relay 5l0 operates and at its Vfront contact completes a circuit over sequence switch contact 53 for the encrgization of sequence switch 500, which therefore advances to position l5. ln this position the called line circuit is closed at sequence switch contact 553 bottom and 548 top. Relay 540 v is therefore energized and at its front contact closes the energizing circuit 'for relay 537.' Relays 533 and 539 are maintained connected in series over the right-hand and lett-hand armatures of relay 537. But the circuit of supervisory relay 00 at the sending switch is opened, and this relay releases and, shunting the condenser 474i, energizes the supervisory relay 262 in the operators cord circuit to extinguish the calling supervisory lamp 256. During the conversation, sequence switch ll00 remains in position 13 und sequence switch 500 in position l5.

Should the operator wish to recall a called subscriber who has hung up she may do so by throwing the cord circuit ringing lrey in the usual way. As the wanted subscriber has hung up the relays 54.0 and 53]7 are deenergized and relay 409 is consequently energized in series with relays 538 and 539. lWhen the operator depresscs her ringing lrey, alternating current relay 408 at the sending switch is energized and at its front contact places a ground on one side of the junction circuit, thereby short-circuiting relay 539 at the receiving switch. Relayv539 releases and establishes a circuit from ground, armature and front contact of relay 538, armature and back contact of relay 539, relay 552 and sequence switch contact 5.5i to grounded battery. So long as the ringing key remains thrown, this circuit is maintained and ringing current is supplied to the called line over the front contacts and armatures o'l relay 552. When the ringing key is restored to normal, relay A:08 is released, whereupon relay 539 is again energized and the circuit of relay 552 is opened.

The removal of the calling plug from the multiple jaclr by the operator in response to the usual disconnect signals at the end ot the conversation releases relay 265 and thereby opens the circuit et cutoli' relay itl, relay eO and relay e0?. Sequence switch hl0() is energized lin a circuit over sequence switch contact -lt top, back contact and armature of relay 407, sequence switch contact Lll? bottoni to ground and advances-io position ll, in which position is again placed in series with the trunlr circuit by way orf sequence switch contact e103 top and baclr contact and armature ol relay -l25 andy sequence switch contact l2cbottom. Should the called subscriber i'ail to hang up, a circuit remains in this position and the guard lamp 428 is energized in circuit over sequence switch contact bottom, contact e92 of units register litri), sequence switch contact 414: top to ground.

l/Vhen the called subscriber hangs up, relays 53T and 5st() are released as above described, whereupon relay is energized in series with relays 538 and 539. A circuit is established. from ground, armature and tront contact ol relay 423, sequence switch contact 18 bottom and sequence switch e0() to grounded battery. Sequence switch l00 advances to `position l5; the brush carriage is returned to normal by means ot a circuit :troni ground, sequence switch contact el? bottom, armature and baci; contact ot relay 40T and sequence switch contact Alll bottom. 1When the brushes reach Atheir home positionn a circuit is established trom grounded battery, sequence switch contact 422 bottoni, home contact ot' interrupter s45, relay i0? to ground. llelay 4r-07 energizes and opens the energizing circuit for the brush carriage power magnet 44,0 ati its back Contact, while sequence switch 400 is energized in a circuit Vfrom ground, sequence switch contact el? bottom, armature and front contact ot relay 40T and sequence switch conact top and advances to position 17. it the same time the holding magnet fli4l or the brush carriage is energized in parallel circuit over sequence switch contact- 416 bottom.

When sequence switch 100 reaches position 1.6, a circuit is established from ground, heine Contact of trip spindle interrupter 4:35, sequence switch contact 41:01 top, relay 5- sequence switch contact i221 top to grounded batt-ery. Relay T23 is energized and establishes a circuit over its front contact, sequence switch contact yl-lT top, armature and back contact ot relay ll0?, which released when sequence switch 400 lett position l5, sequence switclrcontact 4:11 top `tor the energization of trip spindle magnet 430. -The trip spindle is now returned to normal in which position lower Contact 435 of its interrupter is open thereby releasing relay 423. Trip spindle power magnet 430 is deenergized and sequence switch 100 is energized in a circuit i'roin ground, armature and baclr contact of relay L123, sequence switch contact 4119 top and returns to position 1 so that the sending switch is again in position to receive calls.

When sequence switch 4100 ol the sending switch leaves position 1e,;the trunk circuit is opened at sequence switch i124i bottom, whereupon relays 538 and 539 release. Sequence switch 500 is energized in a eircuit from ground, back contact and armature of relay 538 and sequence switch con-- tact 541 top and advances to position 16. The holding circuit or relays 556 and 557 is opened at sequence switch cont-act 558 so that cutoff relay 565 is released and the called line made free. in position 16 of sequence switch 500 a circuit is closed from ground armature and baclr contact of relay 506, sequence switch contact 536 bottom, brush carriage magnet 530 to battery. The brush carriage is thereiore returned to normal and upon reaching its home position a circuit is established from ground, home Contact of interrupter 535, sequence switch contact 503 top and relay 505 to battery. Relay 503 operates and at its back Contact opens a circuit or brush carriage magnet 530 and at its front contact coinpletes over sequence switch contacts 5112 bottoni and 532 bottom a circuit for the energization of sequence switch 500 and holding magnet 531 ot the brush carriage; sequence switch 500 advances to position 18. ln positions 16 to 18 of sequence switch 500 the trip spindle power magnet 520 is energized in a circuit from ground, lower contact of interrupter 525 and sequence switch contact 50T top. Should the brush carriage. reach hoine rst, sequence switch 500 will go to position 18 but as relay 506 is-cnergizcd in position 1T, in circuit troni ground, interrupter 525, sequence switch contact 501 top, the '1ircuit of sequence switch 500 remains in position 18 until the trip spindle reaches its home position at which tinie the ground at the interruptor 525 is reinoi'ed and relay 505 releases and establishes over ils baci: Contact sequence switch Contact 541 bottom.. an energizing circuit 'lor sequence switch 500 which is returned to position 1.

The Sending switch may howere receive a second call even though 'the receiving switch has not returned to its normal posi tion. But if for any reason a sending switch should reach position 5 bejlore the receiving switch is returned to no'inal, the sending switch will remain in this position until the fundamental circuit is closed, as

neeaese described above, which cannot talre place until the receiving switch returns to normal.

As stated above, sequence switch 500 remains in position 10 on busy calls until the connection is released at the sending switch end. rlhe sending switch v100- is in position 13 and when the operator disconnects after taking notice of the busy condition ot' the wanted line, sequence switch A100 returns to normal as described above. 'lhe trunk circuit is opened when sequence switch 100 leaves position 1i, whereupon relays 538 and 539 release. A circuit is established from ground, back contact et relay and sequence switch contact 5521 top for the energization of sequence switch 500, which adF va-nces to position ll. ln position 11 a circuit is established from. ground baci; contact and armature ol" relay 506, sequence switch contact 536 bottoni and brush carriage power magnet 530 to battery and the brush carriage is returned to normal. llilhen the brushes reach their home position a circuit is closed Vi'ronu ground, home contact oi' interruptor and sequence switch contact 503 top for the energization oit relay 50G, which, at its back contact, opens a circuit for power magnet 530 and at its iront contact establishes a circuit over sequence switch contact 51-2 bottoni, for the energization of sequence switch 500 and also over sequence switch contact 532 bottom, for the energization of the brush carriage holding magnet 531. Sequence switch 500 advances to position 12 and Yfrom there to position 10 by means o1 a circuit over the armature and back contact ot relay 538 and sequence switch contact 541 top, and then to position 18 by means oi' a circuit troni ground iront contact ot relay 50G, which has been energized in a circuit over sequence switch contact 503 top and the heine contact oit inter rupter 535 and sequence switch contact bottom. In positions 17 and 18, relay 500 is energized in a circuit over thel lower contact of trip spindle interruptor 525 and sequence switch contact 504. top. The trip spindle is returned to its normal position, the circuit of its magnet 520 being closed from ground at the lower contact ot interruptor 525 and sequence switcl contact 50T top. TWhen the trip spindle reaches its home position the ground at interrupter 525 is removed and relay 505 is released, `whereupon a. circuit is established troni ground, armature and bacl; contact oi relay 500 and sequence switch Contact 5M bottoni 'for the energization of sequence switch 500, which returns to normal position.

Vlhen a subscriber at the exchange served by the above described automatically operating switching mechanism is wanted on a toll call, the toll switching operator at the request of the toll operator assigns a junc- CII incasso tion line tor the call, by rneans ot an order wire,in the well known manner. Vitssuining that Junction line shown in llig. 3 has been assigned and the toll operator has connected the calling line thereto, the switching operator, i'lf the jack 254 of the desired line is found tree, inserts a junction plug 305 therein. The-connection then progresses to the desired line in exactly the saine manner as on the local call as described aborc, 'with the following exceptions: As stated above, when the fundamental circuit is opened tor the second and last time at the back ot' relay 425 sequence switch 400 of the sending switch is in position 8 and sequence switch 500 ci the receiving switch is in posi tion 5; sequence switch 400 advances to position 10 and sequence switch 500 advances directly to the talking position l5. .in igiosilions l0 to l2 inclusive, of sequence switch 400 a circuit is established troni the 48 volt toll cord 1'attery 808, winding o'l' relay SiS, winding ot' repeating` coil 314, lower baclr contact and armature of relay 315, ring of plug 305, ring of jack 254, terminal 444, sequence switch contact 404 top, relay 410 to ground. The current received from battery 308 is sutiicient to causo the energization of relay 410 and the sending switch end ot the trunk line is closed, a circuit being traced from conductor 461 ot the trunk, front contact and armature o1t` relay 410, relay 409, winding olf the repeating coil 470 to conductor 462 ot the trunk. lhen sequence switch 500 ot the receiving switch circuit reaches position 7, relay 506 having been energized in a circuit over the sequence switch contacts 50i and 502 bottom, and the front contact ot relay 410, a circuit is established 'from ground, armature and front contact of relay 506, sequence switch contact 542 top and right-hand high resistance winding ot relay 545 to grounded battery. Relay 545 is energized and a circuit is completed from grounc, sequence switch contact 559 bottom, lett iront contact, armature and lett low resistance winding ot relay 545 and sequence switch 500 to battery. Relay 545 is therefore locked up momentarily and sequence switch 500 advances directly to position 15, relay 545 being released by the opening ot sequence switch contact 559. The ringing positions 12 to 14 inclusive, are passed without the application ot ringing current to the line as in these positions the ringing circuit is opened at the right-hand back contact ot relay 545.

l] ith sequence switch 400 in position 13 and sequence switch 500 in position 15 the line of the wanted subscriber is placed under the direct control ot the toll operator. Relay 409 remains energized until the wanted party answers, as above described. When lill.,

the wanted party answers, relay 409 is deenergized, as described in connection with the local call, whereupon the junction circuit is closed towards the toll switching trunk and consequently the supervisory rclay 313 in the toll trunk is energized and thus eilects the control of the lamp 321 in the saine way as it the toll trunk plug had been inserted into the jaclr ot a subscriberls line directly connected to the manual operators position in the -well known manner. rlhe reringing of the wanted subscriber and the disconnection ot the line at the operators position at the end ot a conversation tal-:e place as described in the case ot a local call.

What is claimed is:

1. ln a telephone system, a linli circuit, two selecting switches, one for each end oi" said linlr circuit, stationary contacts arranged tor selection by said switches, means to operate one of said switches to select a desired contact, a registering device, means to position said registering device in accordance with the particular contact selected, and means to control the contact selecting operation ot the other of said switches in accordance with the sett-ing ot said registering device.

2. in a telephone system, a link circuit, two selecting switches, one tor each end oi said link circuit, stationary contacts arranged tor selection by said switches, means to operate one ot said switches to select a desired contact, a registering device, means to position said registering device in accordance with the particular contact selected, means to control the contact selecting operation oi the other ot said switches in accordance with the setting ot said registering de-` vice, and :means to establish a talking connection through contacts ot said switches.

3. ln a telephone exchange system, calling subscribers lines, an operators position, called subscribers lines, a jack at said position individual to each of said called subscribers lines, a link circuit for extending a calling line to a desired jack, a trunk circuit terminating at each end in an automatic switch, one ot said switches having access to multiple terminals of said called subscribers7 lines, means to operate the other of said automatic switches to seize terminals leading to a jack to which said operator has eX- tended a connection, a registering device, means to position said registering device in accordance with the designation of the ack from which said automatic switch has extended the connection, and means to position said first mentioned automatic switch in accordance with the setting of said registering device.

ln a telephone system, a link circuit,

two selecting switches, one for each end of' said link circuit, stationary ycontacts arranged 'lor selection bysaid switches, means i lected, and means to control the contact selecting operation of the other of said switches in accordance with the setting of said registering devices.

5. in a telephone exchange system, calling subscribersi lines, an operators position, calle-il subscribers` lines, a jack at said position individual to each ot' said called subscribers lines, a link circuit ior extending a calling' line to a desired jack, a trunk circuit terminating at eac-h end in an automatic switch, one ot said switches having access to inultipie terminals or said called subscribers lines, means to operate one of said automatic switches to seize terminals leading to a jack to which said operator has extended a connection, a set o registering devices, means to position said registering devices in accordance with the designation oi the jack from which said automatic switch has extended the connection, and means to position said first mentioned automatic switch in accordance with the setting ot' said registering devices.

V6. .ln a telephone system, a link circuit, two selecting switches, one for each end of said link circuit, each ot said switches being arranged for a plurality of selecting movements, stationary contacts arranged for sele tion by said switches, means to operate one of said switches to select a desired contact, a registering` device, means to position said registering device in accordance with the extent of the successive movements of said switch, and means to control the contact selecting operations of the other of said switches in accordance with the setting of said registering device.

7 In a telephone system, a plurality of Lacasse link circuits, a selecting switch at each end ofr' cach oi' said link circuits, a distributing switch, means to operate said distributing switch to assign for use one or' said link circuits, means to operate one of the select- .i

ing` switches associated with the assigned i` l" circuit to select a desired contact, a registering device, means to operate said regiz-stering device in accordance with the particular contact selected, and means to controlthe contact selecting operation of the her of said switches associated with the as- .igned link in accordance with the setting ot d registerini;` device.

8. fn a telephone system, a plurality of link circuits, selecting switch at each end ci each ot said link circuits, a distributing switch, means to operate said distrib'utin switch to assign for use an idle one of sai link circuits, means to operate one oi' the seecting switches associated with the assigned link circuit to select a desired contact, a registering nevice, means to operate said registering device in accordance with the particular contact selected, and means to control the contact selecting operation of the other o t said swit lhes associated with the assigned link in accordance with the setting oli' said registering device.

9. in a telephone exchange system, an operators position, incoming lines of various jacks at said position, a double switch ended link circuit, outgoing lines, means to extend an incoming line to a jack, means to operate said link circuit to establish a connection from a jack to an outgoing line, a source of ringing current associated with said link circuit, and discriminating means controlled in accordance with the classes of the incoming lines to determine whether or not said ringing current shall be automatically applied.

in witness whereof, I hereunto subscribe myname this l2 day of Aug. A. D., 1921.

GERALD DEAKIN.

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