US1312778A

US1312778A - clauseh

Info

Publication number: US1312778A
Authority: US
Publication date: 1919-08-12
Anticipated expiration: 1936-08-12

Description

I H. P. CLAUSEN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATIOh FILED APR. 13! 1918.

//1 Van for. flew/y f. 6/41/58.

Patented A11 12, 1919,

Affy HENRY P. CLAUSEN, OI? MOUNT V ERNON, Z'IEW' YDRK, ASSIGNDR 1'0 WVEfiTEEN ELECTRIC COMPANY, tnoonroznirnn, or new ren n. Y.,

TELEPHONE-EXCHANGE SYSTEM;

Application filednptil 13, 1912.

To all "to/tom may concern l3: it known that l, Hnnnf: P. CLAUSEX, a citizen of the United States; residing'at Mount vernon, in the county of li'estchester, State of New York. have invented certain new and useful Improvements in Telephone l-lxchangc S i stems, of which the followingis a full, clear, concise, and exact description.

This in 'ention relates to telephone exchange systems employing automatic switching mechanism controlled from the sub s ribcrs" Substations for establishii'ig connections.

The object of the invention is the :provision of a system ctnnprising circuits and apparatus arranged to be controlled from the subscribers conic eit'ectivc after a connection has been e tablished over a train of S\\'li'(l1('.;-3 from one suhacribcfs line to another, ond train oi switches under one of the subscribers. Such subscriber may thereupon cause the operation of the second train oi..'\\"itchcs in accordance with the number of a dcsircd third party, to bring thc third party into the connection. while at the same time the originally established connection is maintained intact and intertercnce by other subscribers prevented by the application of the usual busy condition to each of the several lines con'erned in the conv irsational connect-ion.

More particularly there is contemplated a system in which. a coni'icction'having been built up over a series of switches from a calling to :1 called sulmcribcrs line the called subscriber may thereupon, manipulate his sender to cause the extension of the conversational connection over a second s ries of switches to the line of a third subscriber.

A feature consists in the provision of a special auton'iatically operated hunting switch associated with the final or connector switch, and arranged that. after the connector has completed the connection from the calling line to the called line. a series of impulses transmitted from the called substation to the connector tch serves to initiate the operation of said special switch. Th'ej'special switch has appearing in its terminal bank the terminals or" circuits leading to first selector switches, and when thus set in (meration by theralled subscriber it automatically operates to find the to place a secthe control oi:

Specification of Letters Patent.

substations and which nia be- Patented Ang.-. i2,

Serial Ho. $28.39-

ten-ding the talking conductors of the established connection to an idle first selector trunk. The called subscriber may then send inipuleeg from his station directly to the first selector switch to operate the same. and to subsequently actuate the requisite number of succeeding switches to finally in clude the telephone line of a. desired third party in the conrersatitmal connection previously established between himself and the calling subscriber.

Q! .t .i 3| 7 .ulltll o her feature; as ale contemplateu by the present invention will appear from. a ctnlsidcration of the following description.

In the drawing the figure shows a portion of an automatic telephone system comprising the telephone lines and substations of three subscribers, together with the circuits and switching mechanism employed tot-ting connections between said lines in ac cordance with the princigles of the invention.

lirictiy stated, there is shown a subscribefis substation A consisting of the usual apparatus and the lines of which terminate at the exchane'e in. a preliminaryswitch (not shown) such as a line or finder switch. The substation A is also provlded with an unany number of selectors may be included in the train of switches intermediate of the calling line and the connector. The circuits and apparatus of one of the connector switches C are shown in detail in the lower portion ofthe drawing and include a line relay 8, operating magnets 9 and 10, and movable brushes 11, 12, 13. The brushes 11, 12, are arranged to be dircctirely operated in two separate movewith the multiple terof telephone lines, the terminals or". one of these lines. such as that associated with substation 3. being shown at l-l. 15. 16. A- ociated with the connector switch is a special hunting switch S having brushes 17,

b n'iatzncts 9 and. 1G

in et- Gil , which may be constructed to operate e movementrotary switch, actuated step by means or a. stepping mag- The brushes 17,18, 19 of the spe* ere arranged to cooperate with of circuits which are Associr ed with each of the L provided with one cl these special switches is a solenoid magnet 2-1 adapted to respond to the transmission of a special series of impulses from 21 called substation, as B, to initiate the operation of the said special hunting switch S.

the upper right-hand portion of the drawing are shown in detail the circuits and ug iparatus of another connector switch C" substantially identicel in all respects to the connector already described. This switch is provided with brushes 25, 26, 27 arranged to coiperute with the terminals of telephone lines, and which are shown in operative relation to the line of substation l). A detailed description will now be given of the ope-nation oi thesysteni embodying this invention, explaining first the manner in which a. call is extended from a calling to celled subscribcrs line, and then the manner in which a. second connection may be extended to the line of a third subscriber from the connection already established. For tnis purpose, is assumed that the party at sul'is'tation A desires to converse with the party at substation 13. Upon the removal of the receiver 31 from the switch-.

hook 32, the conductors and 34: or" the calling line are closed to cause the operation of a line or finder switch (not shown in the drawing) in the well-known manner. The subscribernow manipulates his sender 1 to dircctively control the operation of the first selector, and as many succeeding selectors as may be involved, the actuation. of the last of these selectors 2, 3, 4 serving to extend the line 33, 34 by way of terminals 6 and T to u connector switch C having access to the group of lines containing the called line ll. When the selector line brushes 3 and t nmlre c' c'tion with terminals 6 and ,7, the following circuit is closed for the euergimtion of the calling line relay 8 of connector C: buttery, through the upper windingof said relay, terminal 6, brush. 3, through the terminals and brushes preceding switches (not shown), conductor 33, over the loop of substation A, conductor 34:, through the lbrushes and switches preceding the selector 2, 3, 4, brush l, terminal '7, lower winding of rel uy S, to ground. The relay 8 by operating a circuit at its armature and front net for the slow relay 3-5. Relay est terminal 5 to connector SWltCll W i ,s A,

ie 56:13), 30 as its n in 1 ti busy to other s leading to first selecterminals of lower armature and front cont-act also prepares a. stepping circuit for the transmission of impulses to the operating magnets as will presently be seen. The calling subscriber having thus extended his line through selector switches to the'connector C continues to operate the sender l in accordance with the tens digit of the called number. For each interruption produced in the line by sender 1 in the transmission of the tens impulses the line relay 8 retracts and attracts its armature. At the first retraction of the armature of relay 8, the following circuit is closed to send an operating impulse to the primary stepping magnet 9: grounded armature and back contact of relay 8, lower armature and front contact of slow relay 35, winding of slow relay. 36, conductor 37, through the winding or magnet 9, side-switch arm 38 in position 1, to bettery and ground. The magnet 9 energizesl and steps the connector brushes 11,

12, '13 one step forward into operative relation to the first group of line terminals in the tens series, the primary magnet 9 operates to advance the brushes ll, 12, 13 forward one step, finally bringingthem to rest in operative position relative to the tens roup of line terminals including the termimils 14, 15, 16 of the line of the desired substation B. When the first impulse is sent over the albove traced circuit by the linerslay 8, the relay 36 energizes, and being slow to release, retains its armature in attracted position during the short interruptions produced by the stepping relay 8. Upon the encrgizatio-in of slow relay 36, a circuit is established from battery, through the winding of escape magnet 39, contact 40, armature of relay 36, to ground. The escape magnet 39 being designed to move the 'side switch from position to position on denergization, energizes preparatory to advancing said side switch into position 2. At the cessation of the impulses of the tens series, and the consequent maintained. energization of the line relay 8, the circuit of slow relay 3% is held open for :1, sufficient period of time to permit said relay to retract its armature and open the circuit of escape magnet 39. Said escape magnet. thereupon releases the side switch from first to second position. The connector switch is now in condition to receive the final or units series of impulses.

The calling subscriber by operating his sender 1 in accordance with the units digit of the desired number causes the relay 8 as before to retract and attract its armature in correspondence to the number of interruptions produced in the calling line. On the first retraction oi the armature of relay 8, an impulse is trensu-iitted over the following circuit to the SCLClllaly' stepping magnetlil:

Lu e 'lllCl buclr contact of reand font contact of lay 36, conductor 87, armature and contact of relay il, the Wii'iding of magnet 10, side-- s arm 38 and its second position con- I to buttery. The nmgnet operates in response to the JlOSLlI'Q of this circuit and tops rho bri 7 i1, 12, 13 onto the first set s in the selected group. At

.1?) lemon vl suceeec i ,5 ml; *ution of in, armature line relay 8 responsive lo the units of line interruptions, stepping magner 10 operates to advance rid brushes step by o er the-line terminals, und finally as the cessation of said series lLlLGlll'iIO 'resi engagement with the terminals 14-, 15 in 0 inc culled line. The slow relay :lie "rst denergizzition of v e beginning of the secondary "icnl of the switch and remsins enerl during the fOll0'll1; short inter 'upesion or. the primary series of impulses.

, ,"1cstim1 of relay 36 again closes u cirr the operation of escape magnet- 39 nutorg. 23o releasing the side switch end to third position. If the called rnisj-J, :1 ground poen iz1l is present on t ierniinsls 16, having been applied V r o either from u side-switcl'i. arm simiir to arm l2 and its third position contact oilaer "rector switch, provided me busy as u culled line, or from u finder l' i switch provided. the line is busy as u l 'ne. Under this assumption, when ,7 reps its brushes 11, 12 and o ierinin is 1%, l5 and 16 at the end of he one selec moremenl', and u suliicient period. of time nus elapsed to permitlue deenerg'izution of slow reluy36, u-ncw holding sill i. Riel l for escape magnet 39 o rqc-bc'fore breuk Contact l0 before said ce'cnergize, due lo llie severance II us; can

l'fifll'llj by the retraction of holding circuil; may be pole of buttery, through oi: escape mugi'iet mnlzecon ine!" l0, winding of rcluy i I 'de-switcli urm in its secwsition, test brush 13, to the grounded Escapev magnet 39 therefore lied and prevents the release it i: switch in-eo third position. He-

lay 41 energizes in the circuit just traced said at its lois'cr armature and the malts i iii-- outset l3, clrrs n holding cirour: escape nnigz ne'r. lrmn f magnet 9,

no winding :2

1g 01 relay ll, contact: c of said reluv, to ground prod e. by said relay 8 in the .mzm- *SCI'EUQCl in connechon with tlietrunss to conductor 64, which bus tone is induc.'

lively transmitted in the well-known mun nor to the substation apps ntus of the calling line. The culling party being thus informed that the desired line is busy replaces his receiver on the switclihook, thereby cuus- .ing the denergizution of the connector line relay 8. Relay 8 on retracting its iii-nurture permanently opens the circuit of slow rcluy 35, which in turn deencrgizes and completes the following circuit for the connector rc- -lcase magnet 47: buttery, through the winding of magnet 47, primary off-normal contact 48, back contact and lower armature of relay 35, buck COIIl'iLCt and armature of relay to ground. The release magnet energizes and restores the connector switch C to its normal position. lVllcn the switch is completely restored the primary off-normal -contact is again opened, thereby opening the, circuit of magnet 47 umuew the some to deencrgize. The slow reluy on releasing also removes at its upper iii-mature the busy ground from the selector testerminal 5. The removal of this ground potential from terminal 5 may opcrnte, as is well known, to

cause The restoration of the selector switches reaching third position. places u busy ground on the test-terminal 16 of tlio -nllcd line, and also closes n circuit for relay 45), which ulstrncts its arnuu'ures to connect the talking conductors 50 and 51 through to brushes l1 and 12 respectively. The circuit for l'QiZi 49 is traceable from buttery, through the winding of such relay. contuct and outer arnniture of relay illlllill'llle and conflict of escape nuzgnc' 2-35.), iuncr :u-umrurc and contuctof relay side-su'ilclr arm 42 in position 3, to ground. Willi the side switch in this position, o circuit is also closed us follows for the ringing relny 53: frec'pole of battery, sidc-switcl1 arm 38, conductor 54, upper armature and contact of rii'iging cutoff relay 55, through the winding" of relay 53, interrupter 56, to ground. The interrupter 56 operates to interiniltenl'ly onerund dci nergrizc the relay 53. which by 1 corresponding :ittrnciion and rclruction of its nrniuturcsintcrinittcnl'ly applies the ringing source of current indicated at 57 to {be willed line. The ringing circuii may be traced from source 57, "from coniictand outer nrnuiture of relay 53, conductor 51, inner nrnmture and contact of relay 4-9,

. which, after a talkino connection mg of relay 58,

armature and contact of relay brush 12, terrninal 15, over the loop of called substation B, including-the ringer thereof,

terminal 1%, brush 11, contact and upper arinature of relay 49, conductor 50, to ground at the inner armature and front contact of relay 53. When the called sl'lbscriber removes his receiver, and during; the period of operation or interrupter 56 that the armatures of relay are retracted, a circuit is established as follows for. the called line relay 58: battery, through the upper Windconductor 59, contact and left-hand armature of slow relay 60, lefthand armature and back contact o:t' slow relay 61, closed contact of solenoid magnet 24, conductor 63', back contact and outer armature of relay 53, conductor 51, inner 4:9, brush 12, terminal 15, over the loop of substation B, terminal ill, brush. 11, contact and upper armature of relay 419, conductor 50, inner armature and back contact of relay 53, contact and right-hand armature of relay (30,

conductor 84, through the lower winding of relay 58, to ground. The called line relay 58 on energizing closes a circuit for the ringing cutoff relay from battery, side-switch arm, 38, conductor 54, through the Winding of relay 55, conductor 65, lower armature and contact of relay 58, to ground at the off-normal contact 66. Relay 5-5 at its upper armature opens the circuit of ringing relay 53 to discontinue the ringing op'eratiom'and atits lower armature closes a locking circuit for itself independent oi relay 58. Theilines of the calling substation A and called substation B are now connected through for conversation, talking battery current being fed to the calling line through the windings of relay 8, and to the called line through the windings of relayv 58. ..Condensers 67 and 68 inserted in the talking conductors serve to coni'lucti ely separate the calling and called lines. versation the calling party by replacing his receiver to the switch hook causes the restoration of the established connection as has been explained hcreinbeforc.

After a calling subscriber, as A, has cornplcted the extension of a telephone connec tion between his line and that ol a called subscriber, as B, in the manner above described, it may be desirable, due to the inability of the called subscriber to give the calling party the full information required, or for other reasons, to bring a third subseribers line into talking relation to the already esta-hhshed connection. The case will now be assumed in has been built up between th llinesjt and id, it is desired to include the line D .in the conversa tional circuit. To attain this end it is only necessary for the called subscriber at B, While holding his receiver on the hook, to

manipulate the sender 35) to transmit to the sion of the desired tive in controlling the to conductor closes a circuit for the magnet 24 from battery, through the winch ductor 72.

cluding the At the close of the con-- sufiiciently to open contact 2, relay for slow relay grounded outer connector C: first, a special series of impulses which are effective to operate the switch S5 to prepare the Way for the exteneonnection over second train of switches; and. thereailt "l. series of selective impulses Wlswitches or" said train. .l. special ser1es oi": impulses ma operating the sender so interruptions, for exam ple, in of substation Since as ace the called line, relay 58 is now ."gizetl in series with the called line, each interruption in such line causes th relay 5% to retract and attract its arinatures ccrrespcudi ly. upper armature of line relay is to coiiperate with aniahc-before-bre: tact 70 in such manner that said cor is in engagement with its grounded 71 for a. briei interval during both neretracting and attracting movements of the armature of relay 58. Hence, the relay 58 operates in response to the-ten successive interruptions produced by sender 6. the ten successive deiinergizations and energizetions of. said relay result in twenty l!lGlTL-;ll tary ground connections being; applied to the conductor 72.. he application of. ground solenoid ing; of said magnet, to the grounded con- Solcnoid 12% is constructed such that the receipt of the twenty impulses producedby the operation of relay 53 is Smilicient to attract its plunger 73 to a position Where it becomes effective to open the contact 6 It will be noted at this point that the winding of slow relay 61, and the path inleft-hand armature and heel; contact of relay 6]. and contact 62, in parallel with each other, both being in rics with conductors Ti and 63, which c nductors comprise a part of the above traced circuit for line relay 5S. Normally then, the relay 61 remains inert, being shunted out by the low resistance path through contact But when solenoid 2iatt-racts its plunger energizcs and completes the following hand armature and frontcontact of 61, through the Windingof relay $0, right-haiul armature and contact of 61, contact 75, conductor 76, Windin of slow relay 77, to battery. Relays ant. .77 both energize in this circuit. The attraction of the armatures of relay 6!) opens circuit of line relay 58 and slow. relay 61. becomes deenergized, but the relay 61 is so adjusted as to retain its arinatures attracted until the quick acting; switch 8 has had time to step brushes ill, l8, 19 over the en e row of truult terminals 21, The sei'cl S 1. vi tne pro e-r the hunting period of has no normal position, but is adapted when not busy to steed with its brushes 17 18, 19 upon the terminals of the selector, such as the selector indicated at 78, 79, 80, last used in the extension of :i connection. It then the selector upon the trunk terminals 21, :22, 28,0f which the switch 55 is standing, is busy y reason 01 having been taken for use in the extension of a cal scriber in. the system, a ground will he present on the test terminal 23 of the switch S. This ground may either front contact of the first slow relay of selector 78, 79, as is Well known or from the front contact of the first slow relay at the connector switch, as the relay 35 of conneci'or C and re. 81 oil connmtor L. Therefore, on the encrgizution of relay 7? uhoi'e dcscribed, a circuit is closed as follows for the stepping magnet 20 of special switch but side-suite- 38 in third position,

' i wi: ling of in contact thereof, on 1 ure relay 7?, bee-5 inner lower armature of relay erouiulcd terminal and opens own ance the brushes ll, 18 I inuls of trunks leuclin rut selectors, until the terminals in, trunk l ading to an idle se 1 reached. llhen -.i.'cluy the circuit of inuggnet thcreii'i'rh nus also winding1 oi 1 re-- :1 i V L r 1 mature 3.310. contact J V estnolish relay luy is set i from open 28 .1 1e time that magnet is stepping test brush 19 over grounded terminals. But when the non-grounded terruins-.1 is reached, suliicient current flows to relay 83 to cause its encrgizution. The stepping magnet 20 is included in series with relay 83, but the resistance of relay 83 being so high said magnet does not energize. The operation of relay 83 completes a circuit from battery, through the Winding of the line relay (not shown) of the first selector 78, 79, 80, terminal 21", brush 3?, contact and inner upper armature of relay conductor 8%,

eel: Contact and inner urniuture of relay conductor 50, and thence over the called line B as before traced, returning by conductor 51, outer armature and hook contact of relay 53, conductor 63, winding of slow relay (S1, left-hand armature. and front contact thereof, conductor 85, middle lower armature and contact of relay 83, brush l8, terminal 22, to ground through the other Winding of the selector line relay (not shown). which held its flllnlillul'GS attracted during switch 8. end while its circuit Was maintained opened by relay 60, is again energized in the circuit aho ve traced.

l by some other sub-- be derived from a.

' front contact Relay G1;

ill

The attraction of the upper armature of re lay 83 closes a substitute circuit for slow relay (S0 to replace the one )rcvi.)usly described. The uttruction of the inner lower urnuiture of relay 83 closes a holding circuit for said relay in place of its original circuit. which is SO-VGI'QIl by the ilei ncrgizution of slow relay 7'? shortly after the opening of Contact 75. lhiscircuit uury be traced from battery, side-switch arm 38, conductor 82, winding, armature and contact of magnet 20. Winding, front contact and inner lower a1 nurture of relay 83, test hrush 19, to the test terminal 23 which has been grounded upon the seizure of selector 78, 79, SO in the wellknown niaiin The line oi the first culled substation ll has now been extended liy Wu: 0'! the hunting switch S to u lirst selector nll'lllfll TR. 79, R0. The subscriber on operuting his dial (Bi u= suid selector to more inio engagement .1 terminals S6 87, lending to the connector C which in turn has access to the desired line D. (in the seizure oil the connector C u circuit is completed for line relay 85) as follows: buttery, through the upper windingoi relay 8 terminal 66, brush TS, termiuul 21, brush 1?, contact and inner upper lll'll'lilllllfi of relay 83. conductor contact and inner 53., conductor 50, contact of ml 14, over upper rcluy l9. brush ll. the loop of substation l6. sh l2, routucl; and lower ur- ,cenducmr 5] outer urniuontuct o'l' relay 53, conductor 5i. lellalmud armature i act of said relay til. iniddlc nature i lcontmtolrelay1'3. brush l8, terminal hrush 79, terminal lower Winding: of role 39. to ground. Reluv 89 thus becomes energized in series with the first culled line B, and closes u circuit for slow relay 81. Which places u ground at its ower urinature on test Wire 30 to render the switch C busy, and ulso to hold the circuit closed for relay 83 us uhove explained. The subscriber no operutes sender (3!) to send the tens and units impulses to the connector ln response to the tens series rela 80 vibrates its armature and at each refraction. a circuit closed as follows lmprin'mrx stepping magnet 90: grounded ouch Contact of relay 8!),

armature and inner armature mid of relay S1, wincin of slow relay '91, Winding of magnet 90, side-switch arm 92. to huttr 3 he escape magnet Sit-B is energized as Well understood and at the end of the tens impul. u'ics' releases the side switch into second position. In response to the units impulses the following circuit: is closed for the secondary stepping magnet 9i: grounded armature and back contuct of reley 89, inner urnuiture and frontcontact of relay 8]., Winding of relay ill. lelehzmd armature and contact of relay 95, through the winding of magnet 94-, side-switch arm 92 in second position,-to battery. Magnet 94 operates in this circuit to, advance brushes 25, 26, 27 over the group and into engagement with the terminals of thGSSGCOHCl called line D. Assuming line D to be idle, escape magnet 93 deenergizes at the end of the final series and steps the, side switch into third position. In this position of the side switch the ringing relay 96 is intermittently-actuated to apply ringing current to the called line in amanner similar to that described in connection with connector C. \Vhen the subscriber at substation D responds the called line relay 97 energizes, thereby causing the ringing operation to-cease as already ex- .plained.

The telephone line of the third party at D has thus been included in the connection and all three subscribers may converse with one another. Talking battery current is fed to the substation A through the windings of the calling line relay 8 of connector C, as in the case when the established connection involved only the calling and first called subscribers. But the first called substation B is now supplied. with talking current through the windings of the calling line relay 89 of the connector 0 instead of the called line relay 58 of connector C. The second called substation D receives battery current from relay 970i connector switch C. The conversational circuit between lines A and B is conductively separated by

condensers

67, 98 and 68, 99; the conversational circuit be tween lines A and'D by condensers '67, 98, 100 and68, 99, 101; while that between lines B and D is separated by condensers 100 and 101.

At the completion of conversation, the calling party atA'hangs up his receiver to efi'ect a release of connector C and the remaining switches in the t ain interconnect- 'ing his line with that ofsubstation B,-as has already been set forth. When brushes 11,

. 12, 13 of connector C break engagement with the terminals of the called line B, the hereinbefore traced circuit of relay 89 is severed, thereby resulting in the release thereof. Retraction of relay 89 causes the deenergization of relay 81; which completes the following circuit for release magnet 1020f connector C: battery, through the winding of magnet 102, primary off-normal contact 103, back contact and armatures of relays 81 and 89 to ground. The connector switch C is thereupon restored to its normal position. The selector switches preceeding connector C are likewise released at this time.

What is claimed is: 1. In a telephone system, a calling line, a called line, means for establishing a connection between said lines, a third line,

' an automatically operated hunting switch,

aeiarre means controlled by the called subscriber for initiating the huntingmovement of said hunting switch to extend the established connection in the direction of the third l and means controlled by the calleds scriber for completing the extension of the established eonnectionto said third line.

2. In a telepl'n'me system, a calling line. a called line, selector and connector switches for establishing a connection between said lines, a third line, an automatic step-bystep hunting switch individual to said eonnectors, means controlled by the called subscriber for initiating the hunting movement of said hunting switch to extend the established connection in the direction of the third line, and means controlled by the called subscriber "for further extend n the established connection to said third line.

3. In a telephone system a calling line, a called line, sending devices associated v: said lines, means including selector and connector switches for establishing a coin nection between said lines, a third line, an automatiuilly operated hunting switch.

means controlled by the called subscribers sending device for starting the huntii'ig movement of said hunting switch to extend the established connection to an idle selector switch, and means controlled by the called subscribefis sending device for operat a said selector and succeeding swit s further extend the established conn ion to said third line. i

. at. In a telephone system, a calling line, a called line, impulse senders associated with said lines, means including selector and con- 5. In a telephone system, a calling line, a

called line, an impulse sendenassociated witi the called line, a train. of automatic switches, means for operating said switch s to establish a connection between said li 3s, a third line, an autonnitically operated hunt ing switch, a second train of automatic switches, an electromagnetic device and means including said sender for transmitting impulses thereto, said device responsive to a predetermined number of impulses start the hunting movement of: said hunting switch-to extend the established ccnnec to said second train of switches, and means controlled by said sender for operating said second train of switches to further extend the established connection to said third line.

In a telephone system, a calling line, a called line, an impulse sender associated with the called line, a train of automatic switches, means for operating said switches to establish atalking connection between said lines, an automatically operated hunting switch associated with the last switch of said train, a third line, a second train of automatic switches, means controlled by said sender for initiating the hunting movement of said hunting switch to extend said talking connection to the second train of switches, and means controlled by said sender for o eratin said second train of b switches to further extend the nection to said third line.

In a telephone system, a calling line, a called line, means for establishing a connection between said lines, a third line, a plurality of trains of automatic switches arranged to extend said established connection to the third line, an automatically operated auxiliary switch arranged to test the talking concondition of the first switch in each of said trains of switches, means controlled by the called subscriber for starting the testing operation of said auxiliary switch to select a train of switches, and means for operating the switches of the selectedtrain to include I said third line in the established connection. 8. In a telephone system, a calling line, a called line, impulse senders associated with said lines, a train of automatic switches,

I means controlled by the calling subscribers sender for operating said switches to estab lish a talking connection between said lines, a third line, a automatic switc es adapted to extend said talking connection to the third line, an ad; tomatic auxiliary switch arranged to test and select the first switch in each of said plurality of trams of switches, an electrolurality of other trains of magnetic impulse device and circuits con trolled thereby, means including the called subscribers sender for transmitting impulses thereto, said device being responsive to a definite number of impulses only to control said circuits to initiate the testing movement of said auxiliary switch whereby a talking connection.

In witness whereof I hereunto subscribe my name this 3rd day of April, A. D., 1918.

HENRY P. CLAUSEN.