US1575140A - Telephone-exchange system - Google Patents

Description

March 2 1926. 1,575,140

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14 5 s t 1 March 2,1926. 1,575,140

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 1925 14 Sheets-Sheet 2 b Amz S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM March 2 1926. 1,575,140

Filed March 31 1925 14 Sheets-Sheet 5 v March 2, 1926. 1,575,140

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14 Sheets-Sheet 4 March 2 1926. 1,575,140

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 1925 l Sheets-Sheet 5 M rh 2,1926. 1,575,140 S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 19 25 l4 s 6 MarchZ 1926. 1,575,140

s. a. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14 Sheets-Sheet 7 hue/7f? Jamue/ 15 W/Y/M/nS March 2 1926. 1,575,140

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 1925 1 Sheets-Sheet 8 fnveman Jdmue/ 5 W/7ll'dms March 2 1926. 1,575,140

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 1925 14 Sheets-Sheet l0 lnvenfoxt' Jamue/ 6i Will/am:

March 2 1926.

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM 14 Sheets-Sheet 11 Filed March 31 1925 //2 van far. 1 fazmze/ 5! [WK/74m:

TELEPHONE EX CHANGE SYSTEM Filed March 31 1925 14 Sh five/277%. Jamue/fi 140/0 10 March 2 1926.

s. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 31 I 1935 14 s t -s t 15 MaQrch 2 1926.

S. B. WILLIAMS TELEPHONE EXCHANGE SYSTEM Filed March 51 I 1925 14 Sheets-Sheet l4 :mx xx R mg $33G Patented Mar. 2, 192 6.

UNITED STATES 1,575,140 PATENT OFFICE.

SAMUEL B WILLIAMS, 0]? BROOKLYN, NEW YORK, ASSIGNOR, BY MESNE ASSIGN- HENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION 01 NEW YORK.

Original application filed September 26, 1923, Serial No. 664,825. Divided and this application filed. Match TELEPHONE-EXCHANGE SYSTEM.

31, 1925. Serial No. 19,577.

To all whom it may comer n:

Be it known that I, SAMUEL B. WILLIA us, a'citizen of the United States of America, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a fu 1, clear, concise, and exact description.

This invention relates in general to telephone exchange systems and more particularly to exchange systems of the class wherein automatic switching apparatus is used for setting up conversational connections.

The principal object of the invention is a telephone system having an improved organization of recording and controlling equipment for exercising a quick and reliable controlover the selective switches.

A feature of the invention relates to the provision of means whereby the switch controlling mechanism records the fact that a party line is being called as soon as the line is reached to prepare for applying the proper ringing condition.

A further feature relates to an arrange ment whereby the controlling mechanism receives information from the recording device on a reverting call and determines the selection of a special circuit for this purpose.

Other features and advantages of the invention will be more clearly understood from the following detailed description and also from the appended claims.

This application is a division of application Serial No. 664,825, filed September 26, 1923, issued as Patent No. 1,550,769, August 25, 1925.

Referring to the drawing, Figs. 1 to 13, inclusive, when arranged in the order illustrated in Fig. 15, disclose an automatic telephone exchange system embodying the features of the present invention.

Fig. 1 illustrates a line switch of the coordinate type for' extending subscribers lines to trunks.

Fig. 2 shows one of the trunk circuits in full leading from the line switch to the first group selector.

Fig. 3 illustrates a portion of a number of first group selector switches of the coordinate type.

Fig. 4 illustrates one, if a number of co- Fig. 6 shows a sender selector switch of the coordinate type which serves to associate the trunks with idle register senders.

Figs. 7 and 8 illustrate one of the record- 7 ing devices or register senders as they will be termed hereinafter.

Fig. 9 shows a multicontact relay connecting device for associating the register senders with the switch controlling mechanisms or markers.

Fig. 10 illustrates a controlling circuit arrangeinent common to a number of the switch controlling markers. 7

Figs. 11, 12 and 13 discloses one of the switch controlling mechanisms or markers.

Fig. 14 is a schematic diagram of the system.

Fig. 15 is a diagram showing the manner 1n which the several sheets of drawing should be arranged.

The line switch 100, the selector and connector switches 300 and 400 and the sender selector switch 600 are coordinate switches in which incoming circuits are connected to outgoing circuits through the medium of horizontal links. The operating cont-acts are actuated by means of coordinate vertical and horizontal bars. For a clear undei standing of the construction and the operation of switches of this character reference is made to the patent to S. B. Williams, No. 1,517,331, issued December 2, 1924.

General arrangement of tlie system.

It is believed that a better understanding may be had of the system and of the features of invention embodied therein by first considering the general plan illustrated in the diagram of Fig. 14. In this diagram the subscribers lines, two of which, 1400 and 1401, are illustrated, enter the exchange and terminate in vertical rows of contacts on the line switch 1402-. The line switch 1402 operating in response to the initiation of the call extends the calling line over an idle trunk 1403 to the first selector switch 1404. At the same time the trunk 1403 is extended through a sender selector switch 1405 to one of a plurality of senders 1406, 1407, etc.

The subscriber now manipulates his sending transmitter and stores u in the selected sender, the record of the ca led snbscribers line. Thereafter, the sender through a connecting device 1408 is associated with one of two equivalent markers 1409 and 1410. The markers are arranged to be taken for use in alternation. If both are idle the marker 1409 will be taken for use when a call arrives. Thereupon, the switching device 1411 is adjusted to render the second marker1410 available for the next call. If, while the second marker 1410 is in use, the first marker is released, the device 1411 will be readjusted so that the next succeeding call is handled by the first marker 1409. Should either of the markers become disabled for any reason, the switching device 1411. would throw the other marker into service permanently so that all incoming calls thereafter will be handled by the available marker until such time as the disabled marker is restored to service.

Following the attachment of the sender to the marker as above outlined, the record of the called subscribers line is transferred from the sender into the associated marker. The marker, thereupon determines the selection of the vertical row of contacts which represents the group of called subscribers? lines containing the desired line. These called subscribers lines appear in a number of coordinate connector switches 1418, 1414, etc. and each such switch accommodates a plurality of the groups of lines. Therefore, it is necessary for the marker not only to determine which of the connectors shall be taken for use, but also to determine the particular vertical group of contacts in that connector in which appears the called line. Having fixed the vertical row of contacts containing the called line in the connector switch 1413, the marker determines the selection of a group of trunks 1412 outgoing fronrthe switch 1404 and terminating in the switch 1413.

Following this the marker determines the selection of an idle trunk in the group 1412 andalso determines an idle horizontal link in each of the switches 1404 and 1413 and then operates the horizontalmagnets to eX- tend the calling line through the switches to the calledsubscribers line. Upon the completion of the connection the marker is released and immediately thereafter the register sender is also disconnected.

Should the calling subscriber desire connection with a party line the marker is arranged to receive information as soon as connection has progressed to a point where the called line is ascertained in the connector switch. This information in the marker is then transferred through the first selector switch 1404 to the trunk circuit incoming from the line switch 1402 where it serves to determine the selection of the proper code of ringing current to be applied to the party line. As will be seen hereinafter for four. party- 'lines a semi' see lective ringingarrangement is employed in the present system. Each party line has four appearances in the connector switch, two of whichare reversed as regards the tip and ring conductors. The ringing equipment in the trunk circuit is adapted to apply a code consisting of either one ring or two rings with the usual intervening intervals. By selecting one of two dilierent codes by use of the marker and by reversing the'tip and ring conductors of the connector switch terminals, two bellson the party line may be rung at a time either with one shortring or with two short rings. The parties at these two substations will differentiatetheir bells by means ofthe codes.

7 In the event that the subscriber on aparty line wishes to make a reverting call,'namely, one to another substationon the same line, the marker receives special information from the recording sender. By the use of this information the marker determines the operation of the first selector switch 1404 to select one of a number of special'trunks 1415, each including a reverting ringing equipment 1416. In this case the connector switch 1413 is dispensed with entirely. Having selected a reverting ringing equipment 1416, the proper ringing condition is ascertained from the marker and is applied to the party line to ring both the called and calling subscribers bells.

Detailed description of establishment of a connection.

Local ofiice caZZ.It will first. be considered that the subscriber of line 101 wishes to converse with another subscriber whose call numberis 2 1 3 2.

\Vhen the calling subscriber removes'his receiver from the switchhook'a circuit is closed from battery, throughthe winding of relay 102, outer back contact of relay 103, through the subscribers loop, inner back contact of relay 103 to ground. Relay 102 operates and closes a circuit frombattery through relay 104, left back contact of relay 105, conductor 106, outer contact of relay 102, conductor 107 to ground. Relays 104, 105 and 108 enclosed'within the broken rectangle pertainlto the verticalgroup of lines in the row 110 of switch100. These relays are brought into action whenever one of the linesof the corresponding group initiates a call.

Relay 104 now'closes a circuit from battery through the left-hand winding of relay 108, right front contact of relay 104, left back contact ot relay 1'09'to ground at the outer left back contact of relay 111. Relay 108 energizes and looks over its inner right front contact, winding of relay 109 to ground at relay 111. Relay 109 energizes and closes an obvious circuit for slow release relay 125. Relay 109 also closes a circuit from battery through the vertical operating magnet 113, outer right front contact of relay 108, left front contact of relay 109 to ground at relay 111.

Relay 108 closes a circuit for relay 105, which energizes. Relay 112 was operated over the left front contact of relay 104, couductor 107 to ground. Relay 105 now opens the circuit for relay 104 which releases and opens the operating circuit for relay 112, but this circuit was previously replaced by a multiple path over the left front contact of relay 105 and outer front contact of relay 102. Relay 112 closes a holding ground for relay 105.

Relay 109 also closes a circuit from battery through vertical operating magnet 114, terminal and switch arm 116 of allotter switch 115, back contact of relay 119, right contact of relay 111 to ground at outer right front contact of relay 109. The allotter switch 115 has a position for each of the several trunks which lead out from the line The allotter switch 115 is operated by magnet 118 and will always take a position of rest corresponding to an idle trunk. Switch 115 is assumed to have been previously operated to find the idle trunk 121. Consequently, vertical operating magnet 114 is now operated and locks itself over the winding of relay 111 to ground at relay 109. -Relay 111 being shunted at this tlme does not operate.

The magnets 113 and 114 operate and prepare the contacts in vertical rows 110 and 120, respectively. Magnet 114 closes a circuit which may be tracedv from battery through the winding of relay 602, left back contacts of relays 202 and 203, conductor 124 to ground at magnet 114. Relay 602 operates and at this time starts a series of operations in the circuit provided for the sender selector 600 in a manner similar to The operations described for the line switch 100. Magnet 114 also closes a circuit traceable from battery, winding of relay 119, contact and winding of stepping magnet 118, switch arm'117 and test-terminal of switch 115, conductor 124 to ground at magnet 114. Relay 119 is slow to release and keeps the circuit for switch arm 116 open during the stepping operation of switch 115. Magnet 118, in operating the switch 115, opens and closes its I own circuit and advances the brushes 116 and 117 to a test-terminal to which no ground is applied by a vertical operating magnet or otherwise. Relay 119, in operating, opens the shunt around the winding of relay 111. Relay 111, therefore, operates in series with the winding of magnet 114. Relay 111 opens the circuit for relay '125 which is made slow to release in order to permit certain operations to take place before its armature is completely retracted.

When magnet 113 operated it closed a circuit which may be traced from battery, right-hand winding of relay 126, inner left front contact of relay 102, conductor 127, outer left contact of relay 108, contact of relay 128 to ground at magnet 113. Relay 126 common to a group of horizontal operating magnets 144, 132, any one of which is able to connect the calling line to an outgoing trunk. With each horizontal operating magnet is associated a relay 133, 134 which will cause an incoming call to be extended to an idle. link in the line switch 100. It will be assumed that the first link 130 of the group associated with the calling line is idle. Relay 126, in operating, closes a locklng circuit for itself through the winding of relay 128 to ground at magnet 113. Relay 128 operates in this circuit. Relay 126 now extends a circuit for horizontal operating magnet 144 which may be traced from battery through the right-hand winding of magnet 144, left back contact of relay 133, right front contact of relay 126, front contact of relay 128 to ground at relay 111, when relay 111 operates as above described. Horizontal operating magnet 144 now operates and causes the connection to be established between the link 130 and a set of contacts in vertical row 110 and also with a set of contacts in vertical row 120. The subscribers line is thereby extended through to the trunk 121.

Ground at magnet 114 now is extended through the winding ofrelay 131, conductor 134, contact in vertical row 120 and wire of link 130, through the right winding of relay 133, both windings in series of magnet 144 to battery, thus providing a holding circuit for magnet 144. The ground at magnet 114 is alsoextended from the wire of link 130, through contact in vertical row 110 and through the winding of cut-off relay 103 which now operates. Relay 102 deenergizes and causes the release of relay 112, provided that no other call is waiting.

Relay 602 in operating closed a locking circuit for itself over its outer right contact, conductor 236 to ground at the inner back contact of relay 204. Relay 602 also connects ground to conductor 235 through relay 203 to battery. Relay 203 energizes and connects ground at its left front contact to conductor 124. The complete release of re lay 125 can now take place and will cause the release of magnet 113, which in turn, opens the holding circuit for relays 128 and 126 which both release. Relay 125 also opens the holding circuit for relays 109 and 108. The release of relay 108 next causes the release of relay 105. The release of relay 109 opens the holding circuit for relay 111 and magnet 11 1. The releaseof relay 128 opens the operating circuit for horizontal magnet 14 1 which now holds up through the wmd- 'ing of relay 183 as previously traced to ground on conductor 12 1. The shunt is now removed from the operating winding of relay .33 and this relay energizes and in so doing shifts the operating circuit for mag net 1 14; onto magnet 132, which now will be ready to take the next call in ithesamc horizontal group. lVith the magnets 113 and 111 deenergized and the allotter switch 115 at rest the line switch 100 is in readiness .to extend another call.

Turning now to the operation of the sender selector 600, the operation of relay 602 closes circuits for relays 60%, 605, 608 and (309, in the same manner as described for relay 102 in the line switch circuit. Vertical magnet 613 is operated over a circuit from battery through its own winding, outer right front contact of relay (308, left front contact of relay 609 to ground at relay 611. Vertical magnet 61d is operated from battery through its own winding, terminal and brush arm of the allotter switch (315, contacts of relays 619 and 611 to ground at relay (509. Vertical magnet 613 connects ground to horizontal group relay (326, which operates and locks in series with relay 628 and the operation of the horizontal magnet 631 takes place as soon as relay (5'11 energizes inthe holding circuit for magnet e14. The vertical magnet tila connects ground to the test bank of allotter switch 615 which will step forward to the set-of terminals corresponding to the next idle vertical operating magnet. Relay 625 energized atthe time relay 609 was energized and its release was subsequently started when relay G11 operated. Belay 625 is slow to release inorder to provide time for certain operations to take place before its complete release.

lVith horizontal magnet 631 and vertical magnets 613 and '614 operated, contacts m vertical rows 610 and 620 will now close with the wires in horizontal link 6330 and the connection is thus established between the circuit of trunk 121 and the sender shown in Figs. 7 and 8. Ground from magnet 61-; is extended to hold horizontal magnet 681 in a manner similar to that described for magnet 1 A of line switch 100.

The ground at the right contacts of magnet 61 1 is also connected by means of a contact in vertical row 610, conductor'23d, winding of relay 20 1 to battery. Relay-201 energizes and connects the subscribers loop through the scndcrselect-or 600 to the sender circuit in Fig. 7. A circuit is now completed from battery through the left winding of relay 700, outer left contact of relay 715, conductor 653, contacts and wire of link 630, conductor 283, lower :front contact of relay 20%, conductor 123, contacts and wire of link 1300f line switch 100, conductor 143, subscriber?s loop, conductor 142, contacts and wire of link 130, conductor 122, upper front contact of relay 204., conductor 232, contacts and wire of linlc630, conductor 652, inner left contact of relay 715, left winding of coil 713 to ground at relay 714. Relay 700 operates in this circuit and'connects ground to relay 709. ielay 7 09, in turn, operates relay. 710 and a holding ground is now extended from the second outer front contact of relay" 710 to conductor (324. Slow-torelease relay 625 can now complete its [release and the release of vertical magnets (513 and 611- of thesender selector will take place in a manner similar to the release of the vertical magnets ofthe line .switch 100 as described above. Horizontal magnet 631 will be held energized by the holding ground just described on .conductor 624. Ttelay 602 was ireleased at the time relay 20 1 operated and the rclease. of the remaining relays related'to thesenderselector willtake place as described above for similar relays-associated with the line switch 100, so that thesender selector 600 will again be in a position to extend a connection from another trunk to another sender.

The operations so far described were caused by the removal from the switchhook of'the subscribers receiver. At the time relay 7 1O operated a circuit was completed from ground at its innermost front contact, conductor. 7 30, through the right winding of coil 713, conductor 758, outer left back contactof'relay 861 to a-source of dial tone. This tone is transferred by induction from the right to the left windingyof coil 713, and may thus be heard by the subscriber who then will set his dial for the sending of the first digit. The circuit is in a condition to receive the lirstseries of :two impulses.

The first break in the line circuit causes relay 700 to release and open ashort circuit across the right winding of relay 7-11 which will operate in a circuit from battery, through coil 716, right winding of relay 711 and right front contact of relay 7 O9. Relay 711 energizes and operates relay 712 which locks over its inner left contact to conductor 730 which is grounded atrelay 710. The complete operation of relay 712 is insured by the locking of relay 711 over the outer left back contact of relay 712 to grounded conductor 7 30. Relay 717 was operated over a circuit from battery through the winding of relay 717, left back contact of relay 718, inner right back contact of relay 719 to ground on conductor 7 30. Another circuit is now closed from battery through the winding of relay 717, middle left contact of relay 711 to grounded conductor 730. A circuit is also closed from battery through the winding ofrelay 7 18, outer left-contact of relay 711 to conductor 730. Relay 718 grounded conductor .730.

energizes and looks over its inner left contact and inner right contact of relay 719 to conductor 730. Relay 712, in operating, ex-

tends a circuit from ground at right contact of relay 711, over the right contact of relay 712, left middle back contacts of relays 7 04: 703, 702 and 701, winding of relay 701, outer left back contact of relay 7 02 to the holding conductor 750, outer right contact of relay 719, outer left contact of relay 711 to The winding of relay 701 is thus short circuited.

When the line circuit is again completed relay 700 energizes and again shunts the operating winding of relay 711 which, therefore, releases, its holding circuit having been opened by the operation of relay 712. The ground at right contact of relay 711 is thereby removed from the circuit described for relay 701, which circuit now includes the right winding of relay 712 and battery. The first counting relay 701 therefore operates and locks itself to battery over its inner left contact, and thereby places a shunt around relay 712 Relay 712 is differentially wound and the current in the right-hand winding is now so much reduced that the relay will release, the release being accelerated by the left-hand winding. It will be noted that relays 709 and 717 are slow to release and, therefore, are maintained energized during the reception of impulses. Upon the second break in the line circuit relay 700 again deenergizes. Relays 711 and 712 again energize as just dc, scribed. Ground from the right contact of relay 711 is now extended over the right contact of relay 712, middle left back contacts of relays 704, 703 and 702, middle left front contact of relay 701 through the winding of relay 702, outer left contact of relay 703 to the holding conductor 750. The second counting relay is now shunted and upon closure of the subscribers line, relay 700 again energizes, relay 711 dee energizes and relay 702 will energize in series with the right winding of relay 712. Relay 702 locks to battery and shunts the windin of relay 712 which again releases. Relay 02 also opens the holding circuit for relay 701 at its outer left front contact and relay 701 releases. It should be noted that the inner left contacts of the counting relays 701 to 706 are made to close slightly before the middle left front contacts open so that the holding circuits for these relays are sure to be closed before their operating circuits are opened.

The first series of impulses now having been completed an interval occurs, during which slow-to-release relay 717 will have time to completely release Ground is thereby extended from conductor 730 over the contact of relay 717, outer left contact of relay 718, left contact of relay 719, conductor 751, right back contact of relay 812, winding of relay 811 to battery. Relay 811 energizes and looks over its lower front con tact to conductor 752, through winding of relay 719, left outer contact of relay 718, contact of relay 717 to grounded conductor 7 30. Relay 719 does not operate in this circuit, being shunted by the previously described circuit. Relay 811 in energizing establishes a connection at its upper front contacts from the counting relays to the relays Th. in the thousands register over conductors 721, 722, 723 and 724. For the present setting of the counting relays 'a ground will be extended from the grounded conductor 750, over the outer left front contact of relay 702, conductor 722, contact of relay. 811, winding of relay B of the thousands register Th. to battery. Relay B locks to conductor 830which is grounded at relay 710. Relay B further closes a circuit from conductor 880, outer left contact of relay B, through the winding of relay 812 to battery,'causing relay 812 to operate and look over its inner left contact, back contact of relay 862 to conductor 830. Relay 812 closes a circuit for relay 861 which now removes the dial tone from the line circuit and prepares a circuit for the application of busy tone Relay 812 also opens the energizing circuit for relay 811 and thus removes the short around relay 719 which therefore operates. Relay 719 opens the holding circuit of the counting relays at its outer right contact and at its right inner contact relay .719 opens the holding circuit of relay 718.

The counting relay 702 releases and also relay 718, which in turn, opens the circuit for relays 719 and 811 at its outer left contact and relays 719 and 811 release.

Slow-to-release relay 717 now again energizes over the left back contact of relay 718 and the setting of the thousands register is thus completed.

The operation of this circuit in receiving the. second digit is similar to that for the first digit as described above, but since only one impulse is sent out, relay 701 will remain energized at the time slow release re.- lay 717 completes its release in the time interval between the second and third digit. Relay 717 now extends the ground from conductor 730, over its own contact, left outer contact of relay 718, left contact of relay 719, conductor 751, right front contact of relay 812, right back contact of relay 822, through the winding of relay 821 to battery. Relay 821 connects the counting relays to the H relays in the hundreds register and locks itself to conductor 752, through winding of relay 719, contact of relays 718 and 717 to conductor 730. Relay 719 is again shunted as described above. A circuit is now extended from conductor 7 50,

ergize.

inner right front contact of relay 7 01', right and 821 release and, slow release relay 717 energizesas described for the first digit.

The setting of the hundreds'register is thus completed and the circuit is ready to receive" the third digit which, in this case, 18' assumed to consist-of tl'iree'nnpulses. Theoperations for the first two pulses will be the same as for the first-digit. Atthe'end' of the third impulse when relay 7 11 deenergizes and the shunt'is removed from relay 703, this relay energizes over acircuit traced from battery, right winding and right front contact of relay 712, middle left back cont-act of relays 704: and 708, middle left front contact of relay 702, winding of relay 703, outer left contact of relay 7043 to ground at conductor 750. Relay 703 operates and opens the circuit for relay 702 and in locl'ring places ashunt around the winding of relay 712 which deenergizes as previously described. heir now slow-torelease relay 717 completes its release,

ground from conductor 7 30*is extended-over its own contact, outer left front contact of relay 718, left contact of relay 7'19, conductor 751, right front contact of relays 812 and 822 and right back contact of relay 832, through the winding of relay 831 to battery. This circuit also extends f-romthe right back contact of relay 832, through winding of relay 863. These two relays en- Relay 8'63 temporarily removes ground from its armature for purposes as will be described later. Relay 831, in operating, connects the counting relaysto the relays T of the tens register and two circuits arenow extended by thecounting relay 7 03, from the conductor 750', one to be traced over itsouter left front contact, conductor 722, contact of relay 831, winding of relay B to battery. The other circuit "is closed at the right front contact of relay 703, conductor 721, contact of relay 831, through winding of relay A to battery. Relays A and 'B operate; locksdirectly to conductor 830, while A Relay B locks over itsinner'l'ef't front contact innerrighflback contact of'rel'ay 864C to conductorSBO. Relay- 832 isnow operated and locked by the operation of relays A and B; The operating circuit for relays 831 and 863 is. opened and the shunt removed from relay 719; The subsequent release of relays7l8, 719 and 831 takes place as through grounded conductor 1010.

previously described and slow-to-release relay 71'7 again energizes.

The circuit isnow ready to receive the units digit, which in the case assumed, consists of'two impulses. The operations in re- ,sponse to these two impulses are the same as described for the firt digit and when relay 717 releases, a circuit is extended from conductor 730, contact of relays 717, 718and 719, conductor 7 51, right front contacts of relays 812, 822, 832, right back contact of relay 842, winding of relay 84:1 to battery. Relay 841 now connects the counting relays to the relays U in theunits registerand the circuit from the second counting relay 702 will be extended through the winding of relay B which locks and furthermore operates the relay 842. This latter relay also locks and opens the shunt around the winding of relay 719 which operates. The operation of relay 719 and the subsequent release of relays 718, 719 and 8 11 take place, whereuponrelay 717 energizes.

\Vhen relay 84-2 operated a circuit was completed from battery left winding of relay 731, conductor 732, outer left front contact of relay 812, inner left back contact of relay 80-1 to ground at contact of relay 863'. Relay 731 energizes and locks over its own right contact, inner left back contact of relay 718, inner right back contact of relay 719 to conductor 730. Ground is now extended from the inner left front contact of relay 73 middle left contacts of relays 733 and 73 1, outer right back contact of relay 7 35, left back contact of relay 736, conductor 901, through relay 91 1 to battery. Rel-(13 911 energizes and closes acircuit from battery through winding of relay 921, right back contact of relay 922, lower front contact of relay 911-, conductor 925, through relay 1001 to ground. Relay 921 operates in this circuit and locks at its left front contact over back contacts of relays 1003 and 1002, though the winding of relay 1001 to, ground. A circuit is newcomplcted for the lower winding of relay 912 from battery over the upper front contact of relay 9'11, upper back contact of relay 914", right front contact of relay 921, Relay 912 energizes and extends ground to relay 922 which energizes and closes a holding circuit. for itself at its inner left contact, over cont'acts'of relays 923 andf924c'providcd relay 924 is operated. Relay 922 also closes a holding circuit for relay 912 from battery over the upper front contact of relay 912, back contact of relay 915,.left front contact of relay 922,. winding of relay 1003 to grounded conductor'1010. Relay 1003 operates in'this circuit and in doing so counects ground from conductor 1010 over the upper front contact of relay 912, to the Winding of multicontact relay 913. Relay

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