US1579838A - Automatic telephone system - Google Patents

Description

April 6 1926. 1,579,838

W. T. POWELL AUTOMATI C TELEPHONE S YSTEM ATTORNEY April 6,' 192s. 1,579,838

W T. PQWELI.

AUTOMATIC TELEPHQNE SYSTEM Filedl March 6. 1923 4 Sheets-Sheet 2 m gvgp GENERATOR FIG, 'Z

C0 NN ECTOR INVENTOR W I N FRED T. POWELL ATTORNEY April 6 1926. 1,579,838

W.T. POWELL.

AUTOMATIC TELEPHNE SYSTEM Filed March e, 192: 4 sheets-sheet :s`

ATTORNEY April 6 1926.

' w. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed March 6. 1923 4 Sheets-Sheet 4 Mm .Pm-OMM n.; 2.3

...una DZDOK DZ( JUK m O OF Grimm ofzow :un: E'

lNvENToR WINFRED T. POWELL ATTORNEY Patented Apr. 6, 1926.

unirsi) stares rarest ois-rice. g

WINFRED T. POWELL, OF ROCHESTER, lilEl` YORK, ASSIGNRTO THE STROMBERG- CARLSON TELEPHONE MANUFACTURNG COMPANY, OF ROCHESTER, NEW' YORK, A

CORPORATION OF- NEW' YORK.

AUTOMATIC TELEPHONE SYSTM. *i

iippiicmion ined March e, 192s. semi no. seance.

To @ZZ iii/wm it may vcon-cera:

Be it known that I, linmean T. Powiim., a citizen ot the United States, residing at Rochester, in the county oi Monroe and State oit New ,Yorin have invented certain new and useful improvements in Automatic Telephone Systems, oi which the following isa full, clear, concise, and exact description. i

This invention relates to telephone systeiiis and more particularly to telephone systems employing automatic switches in completing 4some portion of a telephone connectionbetween calling and called subscribers.

The present invention has for its purpose the provision o'lI iiieans whereby a thei'niionic device directly controls the operation ot one or moreprogressively movable automatic switches. Other features of the invention reside inthe novel circuit arrangement 'for accomplishing this purpose.

'lhe drawings with Figs. `1 and 2 arranged in the order named diagraniiiiatically represent a portion ot` a telephone system Veinploying the present invention. The portion et Fig. l at the lett of the dotted line representsv a calling subscribers telephone line and a non-numerical switch or a line switch for f extending this telephone line. rit the right of the dotted line in Fig. 1 there are representedtho operating circuits ot` a numerical or selector switch. .ln Fig. 2 there are shown the operating circuits of a connector switch, while at the upper right hand corner of this ligure there is represented a called telephone line. Figs. 3 and 4"represent a modified form ot the invention in which tlierinionically controlled circuits govern the variable setting of a register sender.

The non-nuiiierical switch or line switch and registers referred `to may be substantially similar in structure to that disclosed in the patent to Clement 1,107,153, granted August 11, 1914, while the oilierating circuits of the line switch of F ig. l may be substantially similar to those shown in F ig. 49 on page 52 of Automatic Telephony by vSmith E Campbell, second edition. The selector and connector switches may be similar to those disclosed in the patents to vKeith, Erichsoii t Erickson, dlt-815,176 and #815,321, granted March 13, 1906, when modified to operate in a so-called tivo-wire system.

A therniionic device or vacuum tube suitable ior operation in the present disclosure may be similar to that disclosed in the patent toV Allcutt #1,440,432 granted January 2, 1923, in which a filament electrode anda plateelectrode are enclosed in an evacuated space and a third vcontrol element yiny the form oi' an electromagnetic control winding is placed without the evacuated space but withy its held surrounding the .iiist two nien.. tioned electrodes.k l

In vthis disclosure several are indicated, but it will be these symbols merely battery attlie exchange with .the exception of the batteries which are indicated within the dotted rectangles of Figs. 1, 2 and 4 which are employed to control kthe ,therinioiiic device. ln the course oit the `description, these lasty mentioned controlling batteries are referredto as higliand low potential batteries, `but it will be understood that a single high y understood vthat represent one large tomatically*extended through the lineswitch.

in the well-known manner to yanidle trunk leadingto a selector switch such as `tha shown in Fig. l.

switch is seized, a circuit is closed `from grounded battery, through winding 5 ot' the control element of the therinioiiic dei/ice or vacuum' tube 6, conductor 7, left hand winding of relay 8, uppermost, back rcontact and armature of the relay 9, over conductor 10v 'of the selector trunk,., through the `line switch, over the upperv side oi the calling line and through its substation circuits in series, yover the lower side of this line and through the line switch to conductor 1l of the selector trunk, right hand winding oi relay 8 to `ground. The relay 8 is thus operated and at its front contact and armabatteiy symbols voltage battery may bofr employed. instead of these two batteries Vand of the filaments are con- As soon as the''sclecto'r except that it now extends ture closes a circuit for actuating the slow releasingrelay 12, which relay at its lett hand armature and front contact applies a ground potential to the holding co-nductor 13 which maintains the line switch operated. At the right hand armature and front contact of relay 12, a circuit is closed from the low voltage battery 14 for lighting the lilament of the thermionic device 6. It should be noted that the control element 5 of this device acts at this time to block it so that it is inetfective. Ihe selector switch is now in condition to receive impulses corresponding to the hundreds digit of the wanted number, and the calling subscriber thereupon operates his dial sender to send this series of impulses. In response to each of these impulses, the circuit of the control element 5 of the thermionic device 6 is openedV so that this control element is ineffective to control the thermionic device with the result that an operating circuit is closed `for the primary motor magnet 15 of the selector switch from the positive side of the high voltage battery 16, conductor 17, winding of the primary motor magnet, winding or' the change-over relay 18, oil-normal contacts 19, plate 2O and filament 21 oit' the thermionic device to the negative side ot' the battery 16.

The magnet 15 and the change-over relay 18 are energized in this circuit, but when the dial sender again closes the two sides of the calling line, the control element 5 of the thermionic device is energized so that magnet 15 deenergizes, but the changeover relay 18 is slow to release its arma.- tures and is thus held operated during impulses. In response to each impulse, the primary magnet 15 of the selector advances the brushes 22, 23 and 24: one step in their primary direction. In response to the succeeding impulses of the hundreds series the primary motor magnet 15 is energized in a circuit similar to that previously described through the inner front contact and armature of the changeover relay 18 and the cti-normal contacts 25. As soon as the change-over relay 18 is operated, it closes an actuating circuit tor relay 26 Jfromgrounded battery, winding of this relay, uppermost vfront contact and armature of relay 18 to ground.

At the close ot the hundreds series ot impulses the control element 5 of the thermionic device is short circuited in a. circuit closed from grounded battery, control element 5, conductor 27, armature and back contact ot secondary motor magnet 28, lower armature and back contact of relay 18, ott-normal contacts 29 to grounded battery.

The control element 5 is thus ineffective to block the thermionic device 6, with the result that the secondary motor magnet 28 is energized from the positive side of the battery 16, winding of the secondary motor magnet 28, lower armature and front contact ot' relay 26, inner back contact and armature ot relay 18, off-normal contacts 25, plate 2() and filament 21 to the negative side ot battery 16. The secondary motor magnet 28 is thus energized and at its armature and back contact opens the short circuit around control element 5, so that it is now eii'ective to block the thermionic device, which etfects the deenergization of the secondary motor magnet 28. In response to each energization of the motor magnet 28 the brushes 22, 23 and 24 ot the selector switch are advanced one step in their secondary movement. The energization and deenergization ot the secondary motor magnet 28 continues as long as test brush 2a encounters test terminals having a guarding ground potential such as may be applied over a conductor similar to 30 from ground at the lower armature and front contact of slow releasing relay 31. lVhen, however, the ungrounded test terminal 29 is reached, the switching relay 9 is actuated from grounded battery, winding` of this relay, conductor 32, back contact and armature or' relay 26, conductor 33, right hand armature and baci: contact ot motor magnet 28, oilnornial contacts 3%, left hand front contact and armature ot relay 12 to ground. The switching relay 9 on actuation extends the calling line and the conductors 10 and 11 ot' the selected trunk through the selector brushes 22 and 23 to the windings of relay 34; the right hand winding ot this relay is extended to ground, while the left hand winding of this relay is extended to grounded battery through the control element 35 of the thermionic device 36. Relay 3l is actuated in this circuit, and at its armatures and front contact, effects the operation o't the slow releasing relay 31. This last named relay in turn operates to apply a guarding potential over conductor 30 and to close a circuit from the low voltage battery 37, through the filament 38, front contact and armature of relay 31, side switch wiper 39 in its lirst position, uppermost armature and back contact ot test relay 40 to the opposite side of the battery 37. The control element 35 is etective at this time to block the thermionic device 36.

The connector switch is now in condition to receive the tens impulses from the subscribers dial sender. In response to each ot the interruptions ot the extended calling line, the control element 35 is rendered ineffective so that a circuit is closed from the positive side ot the battery 41, winding of the primary motor magnet 42, side switch wiper 43, winding oit the change-over relay dei, conductor 45, plate 46, filament 38, to the negative side of battery Litl. `When the dial sender again closes the extended calling line the control element 35 is eil'ective to block the thermionic device 36, so that the primary motor magnet Ll2 deenergizes. ln response to each energization and deenergization ot the primary motor magnet l2 the brushes 47, 48 and Li9 of the connector switch are advanced one step in their primary movement. The succeeding impulses of the tens series are effective to energize and deenergize the primary motor magnet l2 in the manner just described. n' the lirst energization ot' the change-over relay all, a circuit is closed from ground, its armature and continuity spring, winding of the escape niag-y net 50, resistance 5l, to grounded battery. This circuit holds the escape magnet operated until the close of the tens series ot iinpulses when the change-over relay Llill deenergizes to eiiect the release of the escape magnet 50, which moves the side switch wipers into their'second position.

The connector switch is in condition to receive the units series ot impulses and the calling subscriber now operates his dial sender to eitect the last stage .in the operation ot the connector switch. ln response to each interruption of the extended calling line by the dial sender, the control element 235 is rendered ineffective so that an actuating circuit is closed i'or the secondary motor magnet 52 `trom the positive side ot battery il, winding of this magnet, side switch wiper i3 in its second postion, winding ot the change-over relay ad, conductor elf, plate Li6 and filament 3S tot-he negative side ot battery 4l. The secondary motor magnet 52 and the change-over relay Ltil are energized in this circuit; the change-over relay at its upper armature and continuity spring again causes' the energization ot the escape magnet 50. lilhen the. calling line is again closed in the course ot the operation ot' -the dial sender the control element is tire to cause the dee-nergization ot the recondary motor magnet 52, but the slow releasing changeover relay la remains oper" ated. ln response to each cycle ot energication and deenergization of the secondary motor magnet 52, the brushes ot the connector switch are advanced one step in their secondary movement. At the close et the units series of impulses the control element blocks the thermionie device 36 Afor a relatively long interval so that the changeover relay il deenergizes and effects the deenergiZationot-the escape magnet 50. r his magnet thereupon moves the side switch wipers into their third. position, provided the called line is idle. rllhe escape magnet is then actuated from grounded battery reh` sistance 5l, its winding, side switch wiper 53 to ground. Ringing current is now applied to the called line from the ringing generator, winding oi the trip relay '5i-l, side switch This last named magnet thereupon vdeeuer` gizes and mores the side switch wipers into their fourth or talking position. Guarding potential is applied to the multiple test terminals such 59 oft the called line tlufough test brush i419, side switch wiper (3() in its third and fourth positions to ground. Talking battery is supplied to the calling party through the windings'oic relay 3d, while talking battery supplied. to the called party through the windings ot relay 70. c c

liet is be assumed that the called line is busy at the close oli the units series' ot` impulses, so that when-the change-over relay #ist deenergizcs, a circuit is closed from grounded batter, re; stance l, winding of the esc-ape magnet 50, continuity spring and bach Contact ot relay Ltd, winding ot the test relay hits continuity spring and back Contact, side switch wi 3er 60 in its second position, test brush and through a multi ale test terminal such as' 59` through the test brush such as 49 oit the connector that has previously seized the called line, to ground through aside switch wiper such as 60 in its third or fourth position. The escape magnet is held operated in this circuit and the test relay l0 is operated to close a locking circuit foritselt" through its continuity spring and innermost armature,

oituormal contacts 6l to ground. rEhe escape magnet 50 and the test relay Ll() are thus held operateduntil the calling party` releases. A source of busy tone B Z is then applied to the calling line through the middle armature `and iront contact ot" the test relay l0.

rt the Vclose of the conversation when the calling subscriber replaces his receiver on its switch hook, the relay 34 deenergizes and shortly atterwa ds', the slow releasing relay 3l retracts its armatures. This closes a cir-y cuit t'rom ground at the armature and back contact ot relay 3l oit-normal contactst,

*7 winding ot the release magnet Gi 'to 'grounded battery. The release magnet G4 when thus energized etlects the release ot the connector switch in the well known manner.

rlhe deenergization of relay 3l also remotes the holding ground from the conductor 30 so that the switching relay 9 retracts its armatiues.r On the restoration of ,relay 9 the release magnet 65 is energized ratus referred to is now in condition to extend a succeeding call.

In the modiiieation of the invention shown in Figs. E3 and i the invention is shown applied 'to a so-ealled register sender 'of the type disclosed in my Patent No. 1,- 531,219, issued March 24, 1925. lt will be understood, however, that this type ot register sender may be us al in any system wherein the designation ot the called line is recorded on one or more of a plurality of number storing devices located at the central oliice. The disclosure ot the system of Figs. 3 and f1 has been greatly abbreviated for simplicity in description, but it will be understood that Fig. 4- of' this disclosure may be substituted for Fig. l of my cepending application. It such a substitution is made, relay 106 (Fig. and the conductors leading thereto will be omitted.

It is believed that the present invention will best be understood by describing the method otl establishing a telephone connection from a calling substation such as A to a called substation such as B, reference being had to my mentioned patent for a complete disclosure of the details of the system. lVhen the subscriber at A removes his receiver from its switch hook primary and secondary line switches such as those indicated at 71 and 72 function to extend the calling line to an idle bridge circuit. rlhe extension of the calling line ettects the energization ot the relay 73 over a circuit closed t'rom grounded battery, lett hand winding of this relay, conductor 74e, back contact and armature of relay 75, conductors 93 and 7G of the selected bridge circuit through the secondary and primary line switches, over the lower side of the calling line and through the calling substation circuits in series, over the upper side of the calling line, through the mentioned primary and secondary line switches, conductor 7T, right hand winding ot' relay Z3 to ground. The energization of relay 73 causes the operation of the slow releasing relay 7S. The actuation of relay 78 ettects the operation of relay over a circuit closed trom grounded battery, winding of motor magnet 79, its back contact and armature, winding et the relay T5, outer back contact and armature oi relay S0, back contact and continuity spring of trip relay 81, lower back Contact and armature of relay S2, conductors 83 and S4, inner front contact and armature et' relay 78 to ground. It need only be mentioned that the sender selector switch is normally standing with its brushes 85, 80, 88 and 89 in engagement with the terminals of an idle register sender. For this reason the operation of relay 75 closes a circuit from ground, innner front contact and armature of this relay, selectorl brush 88, conductor 90, armature and back contact of relay 91, winding of relay 92 to grounded battery. The relay 92 is operated and serves to hold the register sender in its busy or operated condition until the release after an extension oi? a call or when the calling subscriber abandons a call. The relay 92 on operation closes a locking circuit for itself through its right hand front contact and armature, which locking circuit is independent et the relay 91.' Also the operation ot the relay 7.3 extends the calling line through conductors 76 and 93, left hand armature' and front contact o1 relay T5, selector' brush Se', conductor 94, control element 95 of the thermionic device 9G to grounded battery. The control element 95 is eilective to block the operation of the device 96 at this time. Simultaneously with the operation of relay 92, the change over relay 115 is operated in a circuit traceable from ground, inner front contact and armature of relay 75, selector brush 88, upper winding ot relay 115, off-normal contacts 90 and 97, left hand front contact and armature ot relay 9S to grounded battery. The relay 92 ot Fig. l closes a circuit for lighting the filament 104 'from the positive side o low voltage battery 105 to the iilament 101, conductor 106, middle front contact and armature of relay 92, conductor 10T to the negative side of battery 105.

lt will thus be seen that the ilament is maintained lighted as long as the register is in use and is maintained in this condition by the relay 92 or by the relay 91. rl`he register sender is now in condition to receive impulses from the calling line over the impulse circuit which has previously been described as including the control element 95. The operation ot the dial sender at the calling substation is eiiective to interrupt this mentioned impulse circuit so that the control element 95 is'ineftective to block the operation ot' the therinionic device with the result that the motor magnet 99 is operated in a circuit traceable from the positive side o't battery 100, conductor 101, -winding ot' motor magnet 99, off-normal contacts 102, lower winding, front contact and armature ot' relay 115, conductor 1023, plate 10T, i'ilanient 10-1 to the negative side of battery 100. The motor magnet is energized in this circuit and since the registers are ot that type which are advanced on the energization of the motor magnet instead of on the deener- (lil gization of this magnet, the brushes of the tens register are therefore advanced into their second position.

It is Well understood that the in its operation intermittently opens and closes the impulse circuit so that in response to the closure ofthe impulse circuit succeedingA the iirst mentioned interruption thereof, the control element 95 blocks the operation ot the therinionic ydevice with t ie result that the motor magnet 99 deenergizes. 1n response to the continued interruptions and closures ot the calling;Y line, the control elementrenders the therinionic device etreetive and ineffective to intermittently energize` and deenergize the motor magnet 99. As a result ot the energization and deenergization ot this motor magnet, the brushes ot the tens register are advanced step-bystep in accordance with the tens designation ot' the Wanted number. Atthe close ot this dial sender series et' impulses, the impulse circuit isy closed tor a relatively long` period so that the circuit including vthe lower Winding ot the slow releasing relay 115 is open iior a short circuited which renders it inetliective tor block the operation ot the therinionic device ro that a circuit is closed to advance the units register troni position 1 to position 2. This circuit is traceable troni the positive side ol' battery 4100 conductor 101, winding of inotor magnet 108, outer lei-'t hand armature and front contact ot relay 92, loiver armature and 'back Contact. ot' relay 115, conductor 108, plate 107, tllaincnt 101 to the negative side ot' battery 100. n

lilith the units register in position 2 a circuit is closed for operating' relay 115 traceable troni grounded battery, lett hand armature and front contacto't relay 98, units register oil-normal contact 109, upper winding; ot relay 115, brush 88. inner right hand armature and Contact ot relay to ground. The short circuit is reruoved troni control element 95 by the opening' otI Contact 9T when the units register leaves position 1, so that the control element is again rendered effective. y

The circuits .are now in condition to rcccive the units series ot impulses. lln rcsponse to the` iirst ot' these .impulses the control element is rendered ineffective sothat a circuit is closed tr'oln the positive side otl l ,.ttery 19D, conductor 101g winding el? the motor magnet 108, off normal contact 110,

lower winding, front contact and arniature ot relay 115, plate 107, tilanient 1011 to the knegative side ot battery 100. r"he motor magnet 108 is thus energized kand advances the brushes of the units register one step. lfn response to the succeeding impulses otl ia. circuit traceable from the positive sido of battery 100, conductor 101, Winding' ot this motor magnet, ortia normal contacts 110, lower Winding, trent. contact and armature oi1 change-over relay 115, conductor 108, plate 10T, lilainent 10a to the negative side 'olf battery 100.

Atthe close ot. this series ot impulses, the impulse circuit is again completed and the control. element interrupts tor a relatively long interval, the circuit including' the motor magnet 108 and the change-overrelay.115. This relay thereupon deenergizes so that this register sender is no longer under the control ot the dial sender. Upon the deenergization ot the relay 115, a circuit is closed tor operating' one ot' the multi-contact relays (not shown) through the units brush 210, uppermost,armature and baclr contact ot relay 115, outer trout contact and armature ot' relay 98, through both windings in series ot relay 111 to ground through the armature oit the relays similar to 111 at other register' senders. 1The relay 111 is thus operated and at its inner lett hand iront contact and armature closes circuit` for operating the relay 112, which circuit is completed at the innermost `liront contact and armature olV relay 92. Relay 112 when thus actuated, closes at its inner armature and trout contact a circuit troni ground, through inner right hand armature, trent contact and Winding ot relay 98, tens register brush 118 and the contacts oit the operated multi-contact relay (not shown) to the test circuit oi the called line. The conipletion ot this circuit starts the priniary and secondary line switches oli Fig'. 3 to extend the called line to the terminating end ot the bridge circuit; to which 'the calling line is already conn-ected. The extension of the called line B to the selected bridge completes signaling* circuit t'roin the ringing); generator, through the lett hand Winding' ot the slouY operating trip relay 81, upper front contact and armature ol relay (now operated) over the upper side ot the extended circuits to the signal at the substation B', over the lower side of the extended connection, lett hand Winding ot the impedance coil 11st to ground.

Then the called party responds, the trip relay 81 is operated to open the circuit ot' the ringing' relay and to complete a *locking* circuit for kitself through its right hand armature and continuity s aring, lower' bach coi'itact 'and armatte ot" relay 82, nconclu'tors `8S and 1 inner 'trent er neet armature the series, the motor magnet 108 is operated oi relay T8 to ground. The operation ot the relay 81 also opens the energizing circuit et the relay T5, whereupon this relay decnergizes and at its inner front contact and armature, the circuit ot relay 92 is opened :ausing it to retract its armatures. rIbis last mentioned operation results in the restoration ot the tens and units registers to their normal positions. The deenergization ot' relay T5 has opened the circuit et the control element 05 so that the release et relay 02 closes a circuit from the positive side ot the battery 100, winding ot magnet 108, off normal contacts 110, outer back contact and armature ot' relay 92, lower back contact and armature of relay 115, plate 10i and Vtilament 104. liiagnet 108 is energized in this circuit and advances t ieunits register one step towards its normal position, however, the energization ot the motor magnet 108 also closes a circuit for energizing the control element 95, which circuit is traceable 'from grounded battery, winding of the control element, conductor 116, 'ront contact and armature of magnet 108, inner Jfront contact and armature of relay 91, resistance to ground. rihe completion et this circuit is eti'ective to block the operation ot the thermionio device so that the motor magnet 108 deenergizes and opens the circuit of the control element, thereupon the operating circuit of the motor magnet 108 is again completed to advance the brushes ot the units register an additional step toward their normal position. The energization ot magnet 108 a1so closes again the circuit for the control element. rthis cycle of operations is repeated until the units register reaches its normal position at which time the cti normal contacts 110 are opened and the ott-normal contacts 10?J are closed. rEhe motor magnet S9 of the tens register is now energized in a circuit traceable from the positive side of the battery 100, conductor 101, winding ot' the motor magnet 9S), ott-normal contacts 102, back contact and armature of relay 99., bac-lt contact and armature ot relay 115, plate 107, lilaiuent 10i4 to the negative side ot battery. The motor magnet is energized in this circuit and advances the brushes ot the tens register one step towards their normal position. The energization ot the motor magnet 90 also closes an energizing' circuit tor the control element 0:. in a manner similar to that aire: dy described. rl`he cycle of operations described 'tor the units register is now repeated in the tens register to cause the operation ot' the motor magnet 09, until the tens register reaches its normal position at` which time the ott-normal. contacts 118 are opened to permit the release ot relay 91 and the consequent interruption of the circuit of filament 1011.

Vhile the operation of this register sender has been described in connection with an au- Lacasse tomatie telepl'ione system such as that' disclosed in my mentioned patent, it will be understood that this invention is suitable for any telephone system wherein registers ure cont-rolled from a remote point to store the designation ot a wanted telephone line and thereafter control the setting ot automatic switches to extend a calling line to a call rd line. The present invention is also particularly adapted for use in a telephone syst cui such as that disclosed in the patent to Lundell #1,108,819 granted January 18` 1910.

llirhat- I consider to be novel in the system ot Figures and t is the use ot' a remotely controlled thermionie device to variably set a series of number storing devices in succession and thereafter cause these registers to control the setting of one or more automatic switches to extend a calling line to a called line.

That is claimed is 1. ln an automatic telephone system, an incoming circuit, outgoing circuits, automatic switching means for extending said incoming circuit to any ot said outgoing circuits, a source of direct current, and means4 including an electron discharge device provided with a control element, an impulse circuit including said control element extending over two sides ot said incoming circuit in series, said control element being governed over said impulse circuit by curr-ent from said source for directively controlling said automatici switching means.

2. In an automatic telephone system, an incoming circuit, a plurality ot' outgoing circuits, a progressively movable automatic switch for interconnecting said incoming` circuit with any ot said outgoing circuits, a source of direct current, and means including a thermionie device provided with a control element, an impulse circuit including said control element extending over the two sides ot said incoming line in series, said control elcment being governed over said impulse circuit by current trom said source Ylor direc-tively controlling the operation oit said automatic switch.

53. ln an automatic telephone system, an incoming circuit, a plurality o'l outgoi y.- circuits, an autoi'natic step-by-step switch 'tor intcrconnecting said incoming circuit with any ot said outgoing circuits, a source o direct current, and means including a thermionic device provided with a control clement, an impulse circuit including .said control clement extending over the t-wo sides ol said incoming line in series, said control element being governed over said impulse circuit by current trom said source for directively governingthe operation ot' said automatic switch.

1. In an automatic telephone system, an incoming circuit, a plurality of outgoing eircuits, automatic switching means for interlll connectingsaid incoming cir-cuit with any of said outgoing circuits, amotor magnet for controlling the operation ot said automatic switch, a surce of direct current, a multielectrode thermionic device directively controlled by current from said source over said incoming circuit, and a circuit for said motor magnet including electrodes otfsaid thermionic device.

5. In an automatic telephone system, an incoming circuit, a plurality of outgoing;` circuits, an automaticswitch for extending said incoming,l circuit to a wanted outgoing` circuit, a motor magnet for advancingsaid auto-y matic switch, a thermio'nic device having a plurality of electrodes enclosed within an evacuated space, a third control electrode ior said tl'iermionic device, said third electrode being remotely and directively controlled `from a distant point, and a circuit of said motor magnet extending,` across the space be outgoing circuits, a plurality oi" motor mag;y

nets operating` in` succession, operating circuits for said motor magnets, a thermionic device having a plurality of electr des within an evacuated space, a control element for said thermionic device arranged to be .directively controlled from a remote point, and a relay for closing the circuits of said motor magnets in succession, the 'operating circuit for one 'of said motor magnets serially inclu'dingg,` the winding` of said relay and the space between said electrodes.

7.,]n an automatic telephone system, au incoming` circuit, a plurality of out3,oing;l circuits, automatic switching' means for ex tending said iucomingcircuit to any oil said outgong crcuits, a source oi' direct current, a thermion'ic device having two .elements enclosed' within an evacuated space, means for causing a space current between said electrodes, an additional element `itor said thermionic device` an impulse circuit in Which said element is connected including' two sides in series oi saidjincoming; circuit.v said element being,` remotely controlled from said source of current, over said impulse circuit to vary said space current, and means including said space current for controlling;

the operation of said automatic switching` means.

8. In an automatic telephone system, an incoming* circuit, a plurality of outgoing circuits, means including; switches and a link circuit for extending said incoming' circuit to a wanted outgoing circuit, a thermionic device having a ilament, a plate and a control electrode for direc-tively controlling thc operation of one of said automatic switches,

and means controlled by the seizure of said link circuit for automatically lighting said filament. i

9. ln anautomatic telephone system, au incoming circuit, a plurality of outgoing;` circuits, means including` switches and a link circuit forextending saidincoining circuit to a Wanted outgoing circuit, a therniionic device having a iilament'Y a plate and a control electrode for directively controlling` the operation of one of said automatic switches, means controlled by the seizure ot said link circuit for automatically lighting` said ila ment, and means for extinguishing` said iilament when the link circuit has been extended to the wanted outgoing,` circuit.

l0. ln an automatic telephone system, an incoming circuit, aplurality ot outooirip` circuits, automatic switching` means `tor extending said incoming circuit to a wanted outgoing' circuit, a plurality of motor magnets` for said automatic switching means, a source ot' direct current, a thermionicdevice havingan input circuit including said source and the two sides of said incoming circuit in series for directively rcontrolling.,y in succession said motor magnets.

- ll. ln an automatic telephone system, an incomin` circuit, a plurality oi: outgoing circuits, a plurality of link circuits, each provided with an automat-ic switch, a thermionic device at each link circuit for governing the operation of its automatic switch7 means in.- cluding a series ofr said link circuits and automatic switches for progressively extending said incoming circuit to a wanted out going` circuit, and means at a remote point for controlling' the thermionic device of a selected link circuit and for disabling the thermionic device oit the. preceeding link circuit in the series.

l2. lnan automatic telephone system, an incoming,` circuit, a plurality of outgoing;

circuits, two groups ot link circuits, each o' i said link circuits being;` provided with an automatic switch, thermionic devices associated with certain of said linkcircuits ot each `uroup for controlling said automatic switches, means controlledover the two sides in series oi said incoming"circuit to actuate a thermionic device whereby a link circuit and its switch in each `group cooperate to extend said incoming' circuit in a connection to a wanted outgoing;- circuit, and 'means controllcd over said connection from the last link circuit thcreotl 'tor releasing saidy connection. n

13. ln an automat-ic telephone system, a telephone line, a plurality of outgoing` circuits, a connecting circuit provided with automatic means for extending` said connectingcircuit to a wanted outgoing circuit over a metallic connection, a thermionic device remotely controlled over two sides of said telephone line in series for directively governing said connection, and means including a nonnumerical switch ior extending said telephone line to said connecting circuit.

1st. In an automatic telephone system, a series of automatic switches each provided with a thermionic device for governing the same, a control circuit common to said thermionic devices, and'means for transferring said control circuit to said thermionic devices in succession.

15. In an automatic telephone system, a calling telephone line, a plurality of other telephone lines each provided with terminals, a source of direct current, automatic switching means including a therlnionic device directively controlled over the two sides of said calling telephone line in series from said source for causing said switching means to connect said calling telephone line over a metallic connection to terminals ot a wanted telephone line, and means etectie subsequent to the operation oic said thermionic device for signaling said called telephone line.

16. In a telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for interconnecting said incoming line with any of said outgoing lines, a source of direct current and an impulse sender associated with said incoming line, an electron discharge device provided with an input circuit and an output circuit, means including said source of current and said impulse sender for transmittin'g impulses of direct current to said input circuit, and means in the output circuit controlled by current impulses in said input circuit for directively operating said automatic switch.

` 17. In a telephone system, an incoming` circuit, a plurality of outgoing circuits, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits, an impulse sender associated with said incoming circuit, an electron discharge device includingtwo electrodes enclosed within an evacuated space, a control electrode external to said evacuated space, an output circuit including said first mentioned electrodes, means including said incoming circuit'and said control electrode for producing energy variations in said output circuit, and means responsive to said energy variations for directivcly op .rating said automatic switch to extend said incon'iing circuit to an outgoing circuit.

1S. In a telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for extending said incom- Lacasse trolling the electrical condition between said electrodes, means including said incoming circuit and said coil in series for producing energy variations in said output circuit, and means responsive to said energy variations for directively operating said automaticswitch.

19. In a telephone system, a telephone line, a plurality of link circuits each provided with an automatic switch, said link circuits and automatic switches being arranged for connection in tandem to extend said telephone line to any outgoing line, an electron discharge device associated with each link circuit, each electron discharge device being provided with two electrodes included within an evacuated space and a coil surrounding said evacuated space to control the electrical condition between said electrodes, means including said telephone line and the electron discharge device of one of said link circuits for extending said telephone line and said link circuit to a second link circuit, and means including a part of said iirst mentioned means and the electron discharge device ot said last mentioned link circuit for causing the automatic switch of said last mentioned link circuit to extend this last mentioned link circuit to an outgoing telcphone line, v

Q0. In a tel phone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for extending said incominO' circuit to any outgoing circuit, an electron discharge device for controlling said automatic switch, said electron discharge device being provided with a pair of electrodes and a controlling electrode, an output circuit including said pair of electrodes, an impulse circuit including said control electrode in series with a control relay and said incoming line, means for generating directive impulses in said impulse circuit for causing energy variations in said output circuit, means responsive to said energy variations for dircctively operating said switch, a releasing mechanism or said switch, and a slow releasing relay controlled bysaid control relay for governing the release of said automatic switch.

In witness whereof, I hereunto subscribe my name this 2nd day ot' March, A. D., 1923.

VINFRED T. POWELL.

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