US1362126A - Telephone system - Google Patents

Description

Patented Dec. 14, 1920.

3 SHEETS-SHEET I.

W. H. MATHlES.

TELEPHONE SYSTEM.

APPLICATION FILED FEB. 20, i917.

W. H. MATTHIES.

TELEPHONE SYSTEM. APPLICATION FILED Fss.2o. 1917.

Patented Eea. i4, 1920.

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W. H. MATTHIES.

TELEPHONE SYSTEM.

APPLICATIUN FILED FEB. 2o, 1917.

Patente Dec. 14, 1920.

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UNITED STATMES .Da rENT OFFICE.

WILLIAM H. MATTHIES, OF HAGKENSACK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORFORATED, OF NEW YCRK, N. Y., A

NEW YORK.V

Application filed February-20, 1917.

To @ZZ 'whom t may concern:

Be it known that LVILLIAM H. MATTH'ins, a citizen of the United States, residing at Hackensack, in the county ot Bergen and State ot New Jersey, have invented certain new and useful Improvements in'Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to the control of signaling means, and more particularly to signaling means employed in telephone systems.

In semiautoniatic telephone systems, especially on calls from a seiniautomatic to a manual otice, it is necessary to indicate to the B operator t-he number of the called subscribers line. In the present practice, itis customary to indicate the number ot the called subscriber by the display ot' prop# eriy arranged lamps before said B operator. The lighting.;` of these lamps is controlled by a sending device operated by the answering or A operator. In the operation of this number-indicating or displaying means, it is essential that the number be not erased until the B operator has disposed of the call, and until the iiumber-indicating means has been placed in condition to receive another call.

The main feature of this invention resides in the provision ot means to associate a set ot' signaling lamps with the trunk on which the next call is awaiting betere the preceding call has been disposed of, and means to prevent the operation of such signals before the number of the preceding call indicated thereby has been erased.

The present invention is designed primarily for use in a telephone system which 'serves to complete connections from a calling line terminating at a semimechanical exchange to a called line terminating at a manual exchange, although the present invention is not limited to this particular use. In the operation ot such a system, the calling subscriber in initiating a call lights a line lamp at the A operators position at a semimechanical exchange. The A operi tor is thereupon connected to the calling line and ascerttius the number of the wanted line and then proceeds to set one or more automatic switches which serve to connect her position with the B operators posit-ion Specification of Letters atent.

CQRPORATION 0F TELEPHONE SYSTEM.

Patented Dec. 14, 1920.

Serial No. 149,789.

been extended to the B operators position a trunk finder previously allotted, connects the circuits of its associated sets of indicators tol the selected trunk. The allotted set of indicators is then operated over the select-ed trunk by impulses from a sender selectively controlled bythe A. operator. It

will ofcourse be understood that other connections may besiniultaneouslv established andv that sets ot indicators associated wit-lil until the station indicated has been called and the lamps extinguished.

The drawings, with Figure 1 placed above Fig. 2, and Fig. 2 placed above Fin'. 3, diagrammatically represent a portion of a telephone system employing the present invention. Fig. l diagrammatically represents indicators or circuit-controlling devices for the number lamps. Fig. 2 diagrammatically represents a trunk nder, an allotter for allotting any one of a plurality of trunk finders for u se, and a lamp allotter for associating a set of number 'lamps with a trunk on which call has originated. Fig. 3 diagrammatically' represents a B operators cord circuit and the means for automatically selecting ringing current. At the left-hand side oi Fig. 3 there is diagrammatically shown an A operators position and an impulse sending device associated therewith.

TWithin the dotted rectangle at the extreme right ot Fig. 2, there is indicated an allot-ter. This allotter is common to a plurality of trunk finders and operates to select an idle trunk finder to care for the next call that is originated. At the left of this allotter there is a second dotted rectangle within which is indicated the apparatus individual to a lamp allotter. This lamp allotter. is also common to a plurality of trunk nders and operates to associate a set of num- It is the ber displaying lamps with a trunk on which a call has originated. In former systems this lamp allotter or selector did not associate a set of lamps with a second trunk on which a call was awaiting attention until the operator had completed the connection for the first call and until the number of the first call as displayed by the set of lamps had been erased.

The indicators, allotters and sequence switches employed in the system are similar in structure to the sequence switch disclosed in Reynolds-Baldwin Patent No. 1,127,808, and are similar in operation and function to the Sequence switches disclosed in Mc- Berty Patent No. 1,125,579.

The trunk finder of this system is similar to the selecting switch disclosed in Craft- Reynolds Patent No. 1,123,696 and may be controlled by circuits disposed in patent to Lundell No. 1,168,319, January 8, 1916.

In this description reference will be made to a fundamental circuit. This fundamental circuit, it will be understood, connects with the trunk terminals as shown at the left of Fig. 3, and includes a stepping relay 389 which actuates counting devices under the control of registers (not shown) set by an A operator in initiating a call. A complete disclosure of the fundamental circuit, of the stepping relay and registers will be found in the patent to Lundell, No. 1,168,- 319, above mentioned.

When the Aoperator has received the number of the wanted line from the calling subscriber, she proceeds to set a selector switch the brushes of which are indicated at 376 and 377 to connect her position with the position of the B operator at the wanted exchange. The A operator thereupon depresses key 383 to connect lier sending device to the selected trunk. The depression of key 383 ycauses the sequence switch 385 to rotate into position 11, in which position the sender is connected through contacts 378 and 381 to the selected trunk. In the meantime the sender' may be adjusted to store up the designation of the wanted line.

When the A operators position has been connected to the B operators position over the trunks 303 and 305, the fundamental circuit is extended to the line relay 306. This circuit may be traced from grounded battery, contact 307, winding of line relay 306, contact 308, trunk 303, terminal 302, brush 376, contact 381, stepping relay 389, contacts 390, 387 and 37 8, brush 377, terminal 304, trunk 305, contact 309, to ground. The line relay 306 attracts its armatures and at its right-hand armature and Jfront contact, completes a circuit from ground, contact 310, magnet of sequence switch 300, to grounded battery, to move sequence switch 300 into position 2. With the sequence switch 300 in position 2, a relay 201 (Fig. 2) is energized over a circuit extending from grounded battery, winding of relay 201, contacts 202, 203, 311, to ground. The relay 201 attracts its armatures and at its right-hand armature and front contact completes a circuit fromv ground through contacts 204, 205, magnet of sequence switch 200, to grounded battery, to move the sequence switch into position 2. As soon as the sequence switch 200 rotates through position 1:15, the relay 201 is energized over a circuit now traced -from grounded battery, winding of relay 201, contacts 202, 209, resistance, back contact and armature of relay 210 to ground. In position 2 of the sequence switch, an operating circuit for. the updrive magnet 206 is closed from grounded battery, winding of up-drive magnet 206, conductor 207, contact 208, right-hand front contact and armature ot relay 201 to ground. The trunk finder switch, designated as 212, eleva-tes its brushes under the control ofthe up-drive magnet 206. As soon as the trunk finder 212 has positioned its brushes oii the termiu nals of the trunk on which a call has been initiated, the relay 210 is energized over a circuit from grounded battery, winding ot relay 210, contacts 213, 214, 215, 216, brush 217, terminal 218, conductor 219, contact 312 to ground. If, however, the brushes of the trunk finder 212 have not been properly centered on the selected set of termi;

nals, the relay 201 is maintained energized over a circuit established from grounded battery, winding of relay 201, lett-hand contact and. armature of this relay, conductor. 220, contact 221, conducting portion of cominutator 222, brush 223, to ground. Vhen, however, the brushes of the trunk iinder have been accurately centered on the selected set of terminals, the brush 223 rests on an insulating segment of commutator 222 and the relay 201 denergizes, completing at its right-hand armature and back contact a circuit from ground through contact 224, magnet of sequence switch 200 to grounded battery, to move the sequence switch into vposition 3. With the sequence switch 200 in position 3 and with the relay 210 energized, a circuit is completed for moving sequence switch 300 out of position 2 and into position 3. rihis circuit may be traced from grounded battery, magnet of sequence switch 300, contacts 312, 13, conductor 314, terminal 225, brush 226, conductor 227, contacts 228, 214, Jfront contact and armature of relay 210 to ground. 1When the sequence switch 300 moves out of position 2, the relay 306 is maintained energize-:l over circuit now closed from groundedY battery, contact 307, winding of relay 306, contact 315, left-hand armature and 'front ccntact of relay 306, contacts 316, 317, over the fundamental circuit previously described, to

groundatv Contact` 309; The relayV 201'` now as; its energizingY circuit. completed from grounded battery, winding oflrelay 201, contacts 202, 230, brush 231, terminal 232, conductor 233, contacts. 318, 319, right-hand ront Contact and armature of. relay 306, 'to` ground. Vith relay 201' energized a cire cuit isl completedV from grounded battery, magnet of'sequence switch 200, contacts 205 and 204, right-hand front contact and armature of relay 201 to ground, Jfor moving this sequence switch into position 4.

A circuit for indicator 100 is noW completed from grounded battery, magnet of indicator 100, contact 111, conductor 142, contact 243, conductor 220, left-hand armature and frontV contact of relayl 201, contacts-202, 230, brush 231, terminal 232, conductor 233, contacts 318, 319, right-hand front contact and armature of relay 306 to ground. As the indicator 100 rotates through its various positions, it operates the contact 109. Each time that the contact 109Y is closed, a circuit for shunting the stepping relay is completedfrom grounded battery, contact 307, Winding of relay 306, contact 315, left-hand armature and con tact of relay 306, contacts 316 and 320, conductor 321, terminal 234, brush 235, conductor 236, conductor112, contact 109, conductor 110, Contact 242, right-hand front contact and armature of relay 201 to ground. The indicator 100`continues torotatethere by shunting the stepping relay until the series of counting relays (not shown) has been energized. The 0 counting relay of the series of counting relays mentioned operates to interrupt the fundamental circuit, thereby causing the relay 306`to denergize.

`When relay 306 denergizes, the relay 201y has its energizing circuit interrupted at the right-hand front contact and armature of relay 306. The relay-201 retracts its armatures, and a circuit is closed for moving the sequence switch 200 outof position 4. ThisV circuit'may be traced from grounded battery, magnet of sequence .switch 200, con tact` 244, conductor 245, contacts 113, 114, 115, 116, 117, 118, conductor 120, contact 246, conductor 247, right-hand back contact and` armature of relay-201 to ground.

In the operation ofv thevv sender thefundamental circuit is again closed from grounded battery, contact 307, Winding of relay 306, contacts 315, 322, 323, conductor 241, terminal 240, brush 239, conductor 238, contact 248, conductor 249, contacts 127, 10e, 105, 104, 10a, 102, 101, Conductor 236, brush 235, terminal 234, conductor 321, con` tacts 320 and 317, trunk 303, terminal 302, over the fundamental circuit mentioned to terminal 304, trunk 305, contactY 3092 to ground. The relay 306- attracts` its armatures, and at-its right-hand armature-com-A Ypletes: afcircuit from ground, right-hand armature vand front contact of: relay 306, contacts 319, 318, conductor 233, terminal 232, brush 231', contacts 230, 202, Winding of relay 201, to grounded battery.

In position 5 of sequence switch 200, a circuit is completed for the indicator 122, which circuitmay be traced from grounded battery, magnet of indicator l22,contact V123, conductor 124, contact 250, conductor 220, left-hand armature and front contact of relay 201, contacts 202, 230, brush 231, terminal 232, conductor 233, contacts 318, 319, right-hand front contact and armature of relay 306 to ground.

Asthe indicator 122 rotates through its Various positions, it closes its contact 125. At this time the contact 125 closes a circuit in shunt of the fundamental circuit which circuit is completed from grounded battery, contact 307, Winding of relay 306, contact 315, left-hand armature and front contact ofl relayv 306, contacts 316, 320, conductor 321, terminal 234, brush 235, conductors 236, 112, contact-125, conductor 110, contact 242, right-hand front contact and armature oi relay 201, to ground. The indicator 122 continuesv to rotate and to operate its contact 125 until a suiicient number of impulses are transmitted to the stepping relay to actuate a series of counting relays, the number of which is determined by the setting of the register mentioned butV not shown. When thevr series of counting relays has been actuated, the fundamental circuit is again interrupted to cause the denergization of the line relay 306. Then the line relay 306 denergizes, the relay 201, as previously described, has its operating circuit interrupted at theright-hand front contact and armature of the relay 306. When the relay 201 retracts its armatures, a circuit is completed for moving the sequence switch 200 out of position 5 and into position 6. rlhis circuit is established from grounded battery, magnet of sequence switch 200, contact 251, conductor 252, contacts 126, 115, 116, 117, 118, conductor 120, contact 246, conductor 247, right-hand back contact and armature of relay 201 to ground. The indicators 127, 128, 129, 130 aresuccessively operated in the same manner as described in the operation of indicators 100 and 122. The manner of setting the indicators 127, 128, 129 and 130 will be readily understood from the setting of indicator 100, and therefore it has not been deemed necessary to describe these operations. These operations, however, are fully described in the allowed application of I. N. Reeves, Serial No. 200,058, iiled November 3, 1917, issued as Patent No. 1,337,482, April 20, 1920. The setting of the various indicators controls the actuation of the series of sets of'lamps of WhichV setn 139 isf al part, which series indicate the digits ofthe desired-number.

The set of lamps is arranged to be actuated through the contacts 140 and 141 of Vindicators 100 and 122 or through the contacts 140 and 141 inclosed within the dotted rectangle and controlled by other indicators similar to 100 and 122.

It will be understood that the fundamental circuit is completed and that the relays 306 and 201 are energized during the operation of each of these indicators. At the close of the operation of each indicator, the

fundamental circuit-is interrupted las de.

tacts 3,12 and 357, conductor 346, terminal over a circuit completed trom grounded battery, contacts 331, 332, winding of relay 330, trunk conductor 303, terminal 302 to ground at a ypreceding' automatic switch through brush 376 and Contact 380. Relay 330 attracts its armature, and while the sequence switch 300 is in'position 4 and when it is rotating through position 5, a

circuit is completed from grounded battery,

contact 333, front contact and armature of relay 330, contacts 334, 335, conductor 336, left-hand winding of relay 337, to ground. The relay 337 attracts its armatures and at its right-hand armature and front contact completes a circuit from ground, contacts 313, 338, right-hand winding of 'relay 337, contact 339, to grounded battery. Relay 337 is maintained energized kin this circuit until the sequence switch 300 moves out of position 7. At the right-hand armature and front contact of relay 337, a circuit is also completed from ground through conductor 314, terminal 225, brush 226, conductor 227, contacts 228, 213, winding of relay 210 to grounded battery. `.The relay 210 attracts its armature and thereby completes a circuit from ground, armature and front contact of relay 210, contact 253, magnet of sequence switch 200, to grounded battery. The circuit operates to move the sequence switch 200 out of position 9 and int-o position 10.

As soon as the sequence switch 200 leaves position 9, the energizing circuit of'relay T210. is interrupted atthe contact.. 213. In

position 10 the relay 201 is energized over a circuit extending from grounded battery, winding of relay 201, contacts 254, 228, conductor 227, brush 226, terminal 225, conductor 314, right-hand arma-ture and front contact of relay 337 to ground. As soon as the relay 210-denergizes, a circuit is completed from grounded battery, magnet of sequence switch 200, contact 255, back con-v tact and armature of Vrelay 210 to ground, to move the sequence switch 200 out of position 10 and into position 11.` Relay 201 is then locked up over a circuit completed through its left-hand front contact and armature, conductor 220, contact 297, conductor 227, brush 226, terminal 225, conductor 314, right-hand armature and contact of relay337 to` ground. Relay 201 is thuslocked up until the operator has plugged into the jack of the wanted line.

As soon as the sequence switch 200 reachesposition 10, the relay 256 which controls the setting of lamp allotter 261 is energized over a circuit established from grounded battery, winding of relay 256, contact 257, conductolr 258, resistance 259, contact 2,60, conductor 220, left-hand armature and front contactof relay 201, contacts 254, 228, conductor 227, brush 226, terminal'225,conductor 314, right-hand armature and front Contact of relay 337 to ground. Relay 256 attracts its armature and at its back contact opens a brealopointin the operating' circuit or" the lamp allotter 261. The relay 256 is maintained energized until the sequence switch 200 rotates out of position 14.

lVith the sequence switch 200 in position 11, and with relay 201 energized, a circuit will be completed for energizing the relay 210. This circuit may be traced from grounded battery, winding of the relay 210, contacts 267, 268 and 269, back contact and armature of relay `264, front contact and armature of relay 256, through front contact and armature of relay 201 to ground. rlhe relay 210 attracts its armature and thereby completesa circuit Vfrom ground, armature and front contact of relay 210, contact 253, magnet of sequence switch 200, to grounded battery, for moving the sequence switch 200 out of position 11. As soon as the sequence switch 200 reaches position 12, relay 264 is energized over aV circuit extending from grounded battery, winding of relay 264, conductor 265, contact 131, conductor 145, contact 266 to ground. Relay 264'attracts its armature, which Vpermits the lamp allotter to associate the set. ofvlamps with the next trunk to be served, but renders the circuits inoperative until the preceding call has been erased. When the relay 264 attracted its are mature, it interrupted at its back contact the energizing circuit of the relay 210, causing this relayto denergize and retract its armature. A circuit isv thus completed from Y130 to ground.

ground, armature and back Contact of relay 210, contact 255, magnet of sequence switch 200 to grounded battery, to move the sequence switch out of position 12 into position 15. While the sequence switch 200 is rotated through position 14 and into position 15, the number of the called subscriber is displayed by means or' the lamp signals in .accordance with the set position or the number indicators in the manner which is fully set forth in the above-mentioned Patent No. 1,337,482.

.lllhen the sequence switch 200 is rotated through position 14 into position 15, an energizing circuit of the relay 324 was also completed from grounded battery, .contact 325, winding of relay 324, contacts 326, 318, conductor 233, contact 232, terminal 231, contacts 230 and 209, through the resistance, Vback contact and armature of relay 210 to ground. Relay 324 attracts its armatures and completes a circuit from ground- .ed battery, left-hand armature and front contact of relay 324, contact spring 327,con tact 328 winding of relay 306, contact 329 At the right-hand armature and front contact of relay 306, a circuit is closed from ground, contact 310, magnet of se- :quence switch 300 Vto grounded battery, to

move the'sequence switch out of position 4. Sequence switch 300 continues to rotate under the control of its master contact 301 until it reaches position 7 With vthe .relay 306 energized and while the sequence .switch `300 -is rotating ,through positions 5 Eto 18, the relay 330 .is energized over a circui't completed from vgrounded battery, contact- s 331 and 322, left-hand armature and frontcontact of `relay 306,.contacts 316 and 347, winding of `relay 330, trunk conductor `303, `terminal 302, brush 376, and contact 380 to ground. Y

When the Bsoperator inserts the plug-341 into the jackof the called line, relay^342 is energized, and withzsequence switch 300 in position 7, a circuit is v.closed from ground, .lower `armature and iront contact Vof relay 342, left-hand armature and -front vcontact of relay 337, .conductor 343, contact 344, magnet Vot sequence .switch 300 to grounded battery, forimoving the-sequenceiswitch into .position V8. As :soonas the :sequence switch 300 .moves .out oi? :position 27, .the locking cir- .'cuit :of `the relay 337 is interrupted at the .contacts-313,338 and 339, :causing this relay to open the energizing circuit of relay 201.

In position 8 of sequence switch 300 ringingcurrentis appliedas follows: Relay 349 is energized over a circuit which may be traced from ground, lower armature and tront contact of relay 342, left-hand armature and back contact of relay 337, conductor 35S, armature and back contact of relay 359,

Vback contact and upper armature of relay l350, .Winding .of :relay le349, =.conductor...351,

contacts 352 and 353, armature and front contact of relay 330, contact 333 to grounded battery. Relay 349 attracts its armatures to apply ringing current through the winding of relay 359, contact 360, lower armature and front contact of relay 349, through the ring of plug 341, through the substation apparatus, tip of plug 341, upper front contact and armature of relay 342, upper front contact and armature of relay 349, contact 361 to ground. Relay 359 is marginal and does not attract its armature until the called subscriber has removed his receiver from the switchhook. Relay 359 thereupon attracts its armature and removes the `shunt around relay 350. Relay 350 attracts its armatures and establishes a locking circuit for itseltl through its upper front contact and armature. This locking circuit, which also serves to short-circuit the relay 349, may be traced from ground, lower armature and front contact of relay 342, conductor 353, lett-hand armature and back contact of relay 337, conductor 358, winding of relay 350, upper armature Aand front contact of this relay, conductor 351 to grounded battery, at contact 333. The relay 350 is maintained energized over this circuit 'during conversation, and the relay 349 is short-circuited, causing .it to retract its armatures, and the calling-subscriber at this time is connected to the called substation.

As soon as the relay 201 denergized when its locking circuit was interrupted at the right-hand armature and Contact of relay 337, when the operator plugged into the jack of the wanted line, a circuit was closed .from ground, right-hand armature and back contactof relay 201, contact 224, magnet of sequence switch .200 to `grounded battery, to move this sequence switch into position 16.

As soon as the sequence switch 200 moves out of position 15, the indicator 100 is .re-

stored to its normal position over a circuit completed from grounded battery, magnet ot indicator 100, contact 135, conductor 136, contact 285, `conductor 247, lright-hand back contact and armature of relay 201 to ground. The .indicator 122 issimilarly restored over a circuit completed, through contact '286.

vThe indicator 127 is restored Vto its .normal position over a circuit established from grounded battery, vmagnet V ofthe indicator 127,.contact 1-37, conductor13`8, contact 287,

y,to ground.V .Theindicators 128, ,129, l39-are ,restored over similar circuits completed circuit .may .be .traced ,from grounded hattery, winding of magnet 270, contact 271, to ground. Under the control of the downdrive magnet 270, the trunk finder switch 212 is restored to its normal position, and when commutator brush 272 engages the normal conducting segment 273, a circuit is completed from ground, through commutator brush 272, segment 273, conductor 274, contact 275, magnet of sequence switch 200, to grounded battery, to move the sequence switch into position 17. Y

' In position 17 a circuit is completed for moving the sequence switch 200 into position v18. This circuit is established from grounded battery, magnet oi' sequence switch 200, contact 276, conductor 277, contacts 132, 1111, 115, 116, 117, 118, conductor 120, Contact 246, conductor 247, right-hand back contact and armature of relay 201 to ground.

At the termination of the conversation the A operator depresses key 383.which causes the sequence switch 385 to move into position 1. The energizing circuit of relay 330 is interrupted at contact 380 and this relay on retracting its armature causes the dee'nergization of relay 324. and this in turn causes relay 306 to be denergized. The relay 306 retracts its armatures and thereby closes a circuit, from ground, its right-hand armature and back contact, contact 355, magnet of sequence switch 300 to grounded battery, to move this sequence switch into position 9. In position 9 the disconnect `lamp 362 is lighted in a circuit which may be traced from grounded battery, the lamp 362, contact 363 to ground. The operator on noting the signal 362 removes the plug 3-1-1 from the ack of the called line. Relay 342 retracts its armatures and thus completes a circuit from ground, lower armature and back contact of relay 342, contact 36%, magnet of sequence switch 300 to grounded battery. The sequence switch 300 now moves into normal position and the apparatus is in readiness for the next call.

It will be understood that the trunk iinder allotter 298 operates to select a trunk inder and its associated set of indicators for use with any trunk on which a call is waiting. As soon as the sequence switch associated with the trunk iinder in use has arrived in some position between 4: and 17, the trunk finder allotter 298 will be operated over a circuit extended from grounded battery, magnet of the trunk finder allotter 298, contacts 299 and 296 to ground. 'Under the control of this circuit, the trunk finder allotter rotates into position to select the next trunk finder to be used. The sequence switch of this trunk finder will be standing in position 18 and will be moved into position 1 over a circuit similar to the following: grounded battery, magnet of sequence switch 200, contacts 205 and 296, through the master contact .of the trunk finder allotter to ground. Since the operation of an allotter of this type is well known and since it is also described in the mentioned application of F. N. Reeves it need not be further described.

Vhat is claimed is:

1. In combination, a selectively operable number indicating device, a plurality of switches, means for operating said switches to actuate said indicating device, mechanism for associating said switches with said indicating device for controlling the same, means for causing said mechanism to associate a switch with said indicating device while another switch is actuating the same, and means for rendering effective the control of only one of said switches.

2. In combination, a selectively operable signal, a plurality of switches for controlling the operation of said signal, a plurality of controllingcircuits, a finder for each of said switches arranged to connect an associatedswitch to any one of said controlling circuits, mechanism for associating switches with said signal for controlling the same, an allotter controlled at said linder for causing said mechanism to associate a switch with said signal while another switch is actuating the same, and means for preventing the actuation of said signal by more than one switch*` at any time. Y

3. In combination, an electric signal, two actuating circuits therefor, a pair of switching devices for controlling each of said circuits, means controlled at a distant point for operating one pair of switching devices, other means controllable at a distant point for operating the other pair of switches, an allotter coperating in the control of one swiching device in each pair, means for causing said allotter to preselect one pair of switching devices while another pair of switching devices is in operation, and means controlled by said allotter for preventing the operation of the last mentioned pair of switching devices' until the first pair has completed its operation. v

4. In combination, a signal, a plurality of switches arranged to actuate the same, a lamp allotter having a plurality of positions yand controlling in its various positions the operationof the switches, means controlled at any one of said switches for moving said allotter into a position permitting the operation of the last-mentioned switch, means effective during the operation of the lirst switch to causesaid lamp allotter to preselect another switch for use, and means operative thereupon for rendering said last mentioned switch ineffective until said first mentioned switch successfully completes its operation.

5. In combination, a signal, a plurality of yselectively operable switching devices ,eacharranged to control said signal, separate means controllable at a distant point for operating said devices, a sequence switch for each of said devices arranged to coperate in their control, an allotter having a plurality of operating positions, means under the joint control of any one of said sequence switches and said allotter for causin one of said devices to actuate said signa means to cause said allotter to preselect a second switching device while another is in operation, and means controlled by said actuated device for preventing the mentioned coperation of allotter and the sequence switch of the preselected switching device.

6. In combination, an operators position, a trunk over which a call is to be extended from said operators position, a second oper ators position to which said trunk may be connected, finder switches, one of which is operable to engage terminals of said trunk, a selectively operable number indicating, device, a plurality of switches for controlling the operation of said device, means controlled from the rst named operators position for operating said switches, means effective during the operation of one ofsaid switches to preselect another switch for use, and means operable thereupon for rendering the last named switch ineffective until the first named switch has performed its operation.

7 In combination, a selectively operable number indicating device, a plurality of switches, means controlled from a distant point for selectively operating said switches to control said indicating device, mecha nism for operatively associating said switches with said signal to control the same, means for causing said mechanism to associate a switch with said indicating device while another switch is actuating the same, and means for rendering effective the control of only one of said switches.

In witness whereof, I hereunto subscribe my name this 19th day of February A. D., 1917.

WILLIAM H. MATTI-HES.

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