US1337740A

US1337740A - Telephone-exchange system

Info

Publication number: US1337740A
Application number: US273118A
Authority: US
Inventors: Jr Samuel B Williams
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1919-01-25
Filing date: 1919-01-25
Publication date: 1920-04-20
Anticipated expiration: 1937-04-20

Description

S. B. WILLIAMS, JR., AND C. F. BALDWIN.

F. D. BALDWIN, ADMINISIRATRIX OF C- F. BALDWIN, DEC'D.

TELEPHONE EXCHANGE SYSTEM. AFFLICAIION HLED JAN-25,1919.

Patented Apr. 20, 1920.

5 SHEETS-SHEET I.

by W A/f'y.

s. B. WILLIAMS, JR., AND 0. F. BALDWIN. F. D. BALDWIN, ADMINISIRATRIX OF C. F. BALDWIN, DEC'D.

TELEPHONE EXCHANGE SYSTEM. AHLICAIION HLEU JAN-25,1919.

1,337,740. Patented Apr. 20; 1920.

5 SHEETS-SHEET Z. F/q. 2.

L T 7 I I I 653 654 65.5 M, 1

hue/770m:

S. B. WILLIAMS, 1a., AND C. F. BALDWIN.

F. D. BALDWIN, ADMINISIRATRIX OF C. F. BALDWIN. DECD.

TELEPHONE EXCHANGE SYSTEM. Armcm|0N HLEIJ JA N.25, 1919.

' 1,337,740, Patented Apr. 20, 1920.

5 SHEET$SHEET 3.

y Af/y.

S. B. WILLIAMS, JR., AND C. F. BALDWIN. F. D. BALDWIN, ADMINISIRATRIX 0F c. F. BALDWIN, DECD. TELEPHONE EXCHANGE SYSTEM. AIILICAIION FILED JAN.25, 1919.

Patented Apr. 20, 1920.

5 SHEETS-SHEET 5.

UNITED STATES PATEN T OFFIGE.

SAMUEL B. WILLIAMS, JR., 0F BROOKLYN, NEW YORK, AND CHARLES F. BALDWIN,

DECEASED, BY FLORENCE D. BALDWIN, ADMTNISTRA'IRIX, OF MONTCLAIR, NEW i JERSEY, ASSIGNOR-S TO WESTERN ELECTRIC CCMTPANY. INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Apr. 20, 1920.

To all ie/(.0712. it may concern:

Be it known that we, SAMUEL B VVIL- LIAMS, Jr., residing at Brooklyn, in tlie county of Kings and State of New york, and Fnoiuinon DAVIS Biimwm, adm1n1stratrix, residing at Montelair, in the county 0i I i-sex and State of New Jersey, citizens oi the United States, are in possession of an invention in. a certain new and useful Improvement in"Telephonc-Exchange Systems, invented by the said Saiiiuni. l5. WILLIAMS, Jr., and (hiAnLns 1 BALDWIN, deccased, of which the following is a full, clear, concise, and exact description.

This invention relates to an indicating system for telephone exchanges and has particularly to do with means for automatically informing the operator in a telephone call distributing system ol the number and, it desired, the class of service oi? a calling line.

In a call distributing system, when a subscriber calls, his line is automatically oxtcudcd to a connecting cord or circuit at an operators position which happens at the time to be available for answering the call and completing the desired connection. In a system of this character it is desirable that the operator shall know the number and class of service of the calling line in order that she may be guided in making the charges For the completed connection and with respect to other duties she must perio in. As the connection with the calling line in such a system is made by means of an automatic switch, and. not by the operator directly, the operator is in ignorance of the numb and class 01 service of the calling linc unless special provision is made for convcying this information to her. It is the object of the present IIIVOHLlOIItO provide a simple and effective organization for accomplishing this result.

In general, the plan of the present 1nvcntion is to provide a number indicating device at the operators osition so arranged as to be brought into connection with any one of the operatoi"s cord circuits to which a call is extended. Associated with each of the finder circuits that act to find and connect with calling lines, is an impulse calling line.

'ator the number and class of service of the The impulse sending switch associated with the finder circuit sends consecutive groups of impulses corresponding in number to the thousands, hundreds, tons and units digits of the calling line, and also a linal set of impulses arbitrarily chosen to indicatc the class oi service ol the calling line.

As the impulse transmitting device is associated with a finder cireuit -that may operate to establish connection with any one of a large number of calling lines, means are provided for (.letermining or automatically selecting the number of impulses in each grou ot' the train transmitted so that the num )er of impulses in the consecutive groups may correspond with the digits in the number of the particular calling line with which the finder circuit happens to be connected. In the type olf' system in connection with which the preferrml embodiment of the invention is illustrated, the finder circuit is connected with the calling line by means of a finder switch having a plurality oi normally inactive brushes and a corresponding plurality of groups of line terminals with which the brushes respectively cooperate. When a line calls, the brush corresponding to the group of lines in 'which the calling line is located, is tripped and made active, and the switch is moved to bring the active brush into engagement with and stop it upon the terminals of the calling line. In the present embodiment of the invention, therefore, the particular brush tripped indicates the line group in which the calling line is located, and the extent of movcmentol the switch in bringing the active brush into engagement with the calling line terminals indicates the number of the line in the line group that has been indicated by the particular brush tripped. In the system of this invcntiomthe impulses for indicating the hundreds digits of the calling line are determined by the particular set of brushes tripped; the impulses "For indicating the tens digits of the calling line are determined jointly by the particular brush tripped and the extent of movement of the switch in connecting With the calling line; and the impulses for indicating the units digits oi. the calling line are determined solely by the extent of moveing the class of service are obtained from a connection which is made. throu h the finder switch with the calling line itse f. In consequence of the above described arrangement, the im ulse transmitting device associatedwith the finder circuit is adapted to send selective trains of groups of impulses that are automatically varied in accordance with the number and class of service of the line with which the finder switch makes connection; so that a single impulse transmitting device associated with the finder circuit serves to transmit to the number indicating device trains of impulses automatically varied in accordance with any line with which the finder switch has the capacity" for making connection.

The rct'erred embodiment of the system .of the invention is illustrated inthe accompanying drawings, in which Figure. 1 shows subscribers circuits and the line finder switch; Fig. 2 shows animpulse sending switch; Fig. 3 shows circuits associated with the line finder switch; Fig. 4 shows a cord finder and a cord circuit associated with an operators position, and Fig; 5 shows the construction of a switch as employed in the line finder. y 1

In the above drawings the invention is shown as applied to a system such as is described in the previously filed application, Serial No. 229.035 (Case 36), filed April 17, 1918, of S. B. Williams, Jr. However, for the sake of simplicity, only so much of the circuits of the previously filed application are disclosed herein as seems to be necessaryfor an understanding o'f the present invention. Those parts of the circuits of the former application which are omitted, and their relation to the present invention, may be understood by referring to the previously filed application Serial No. 229,035, the same reference numerals being utilized as far as possible to designate similar parts in the systems of the present and the previously filed applications.

In the call distributingsystem illustrated in the drawings, two groups of calling lines are indicated, and one line of each of the groups is shown as extending to a subscribers station, it being. understood that the other lines are similarly connected.

As the class of service of the,

modate five hundred lines, ten grou s of fifty lines each. Each of the groups 0 lines has associatedwith it a distributor switch 130, to the stations contact terminals of which" the lines of t at group extend, the.

brushes fo f the distributer switch being @011- nettedliwith group apparatus which is actuatodb'y thev assa'ge' oi the brushes over the terminals 0 a calling line.

, Each of the lines has associated with it a resistance coil 91, and-each line is also provided with one or more springjacks 14 by means of. which connection may it is called; Each of the lines of the various groups may be connected with one of the commutators of aclass-of-service and line niunber identifying interrupter 640, whic ma be common to the exchange.

he groups of lines have access to groups of connecting circuits or cord circuits '00 through the medium of finder circuit F. These finder circuits terminate upon the brushes of pairs of finder and selector switches, one finder switch being dia rammatically illustrated and'designated L and one selector switch being merely indicated at CS. Obviously the finder circuit may be connected with the connecting circuit in any well known wayby switchin means other than an automatic cord se ector switch. The startin of the finder switch LF to find the calling mes is effected by the distributor be made with the line when switch apparatus through the medium of having access to the lines of these groups.

There may be a number of grou s of connecting circuitsUC to which the lines of the various groups of lines have access by way of the finder circuit F, each groupof connecting circuits being associated with a particular operators position. Each connecting circuit may terminate" in a plug 334 adapted, for insertion' in multiple spring jacks339 of lines extending to subscribers stations. Each of the operators positions is provided with apparatus which is common to all of the connecting circuits of that position, and which may be brought into association with any of the connecting circuits either automatically in the extension of a call to a connecting circuit, or at the will of the operator in the course of her supervisoryv operations. This apparatus common to the operators position includesa number indicating device 700 which may be brought into connection with any connecting circuit to which a calling linehas been extended, and WlllCll is selectively operated by means of 717, 712 and 711.

impulses of current transmitted by way of the finder circuit to indicate, by the illumination of certain ones of an associated bank acteristic currents transmitted to it by the impulse sending switch, and to display visual signals varying with the characteristic currents or trains of impulses received. ()ne suitable form of indicatingdevice is the device 7 00 shown in Fig. 1. This consists of a shaft 710 which may be rotated through a pawl and ratchet mechanism by the quick acting magnet 705, and which may be elevated through a similar mechanism by the action of the slow release magnet 704. A set of arms or brushes 711, 712, 717, 719 and 721 loosely mounted on said shaft are adapted to travel over rows of contacts of which there are ten in each row. Associated with each contact is a lamp 735, only the last lamp of each row being shown. "lhe arrangement is such that when a brush is moved to a particular contact, a circuit for the lamp individual to such contacts is partially established, which circuit is completed when all of the arms are set through the contact 7 24 operated at the topmost position of the shaft 710. A yoke indicated at 736 is secured to the shaft 710 and carries a pawl 737, which in the lowermost position of the shaft 710 engages a ratchet on the arm 721, and as the shaft is rotated, rotates such arm. In successive vertical positions of the shaft 710 the pawl 737 engages the other arms 719, After an arm has been operated through the rotation of the shaft 710, it is held retained in its operated position by one of the holding

pawls

713, 716, 718', 720 and 722. A pawl 740 controlled by the armature of the vertical stepping magnet 704 holds the shaft 710 in its rotated position until the shaft is stepped vertically, when such pawl is operated and permits the shaft 710 to be rotated back to normal by a suitable spring not shown. The holding magnet 715 is energized before the indicator is set and is released when the indicator has performed its function. The release of this magnet withdraws the holding

pawls

714, 713, 716, 718, 720 and 722 and restores all parts of the indicator to normal. The particular combination of lamps illuminated in any given case indicates to the operator the number and class of service of the calling line.

Theimpulses for selectively operating the indicating device 700 are applied to one of the conductors of the finder circuit, and through it to a corresponding conductor of the connecting circuit ("(1, by means of an impulse sending switch 620 (see Fig. 3) associated with the finder circuit. Each of these switches, there being one for each finder circuit, is provided with a series of as many stationary contacts as there are digits in the maximum line number in the system, with an additional contact for controlling the class-of-service indication. In the present instance there are five stationary contacts, designated 621 to 625 inclusive. Cooperating with these contacts are three arms or wipers 626 in fixed relation to each other, and so arranged that as one of the arms leaves the last contact of the series an-- other arm engages the first contact. This is in order that the switch may always travel in the same direction and to avoi the necessity of restorin it after it has performed its function. T e arms are rotated by means of the intermittent energization and decnergization of a stepping magnet 630, the pawl 631 being arranged to step the arms forward upon the release of the magnet. The ratchet wheel 633 engaged by the stepping pawl 631 is also engaged by a pawl 632 which acts to insure the movement of the arm to a position where it is centered on a contact, and to prevent retrograde movement. The stepping magnet 630 is made slow to release, as by being provided with a. copper jacket around its core. The impulses that the impulse sending switch 62() applies to the number indicating device 700. pass through the stepping magnet 630; but'as the interruptions between successive impulses of each set or train are short, they do not cause the stepping magnet 630 to release its armature, the release occurring only through a more protracted interruption at the end of each impulse train. This long interruption of the circuit through the magnet 630 permits the armature to release, and thus step the arm 626 to the next contact in the series which the arm engages. The impulse-sending device 620 is also provided with a series of contacts 628 engaged by a set of arms 627, the arrangement being such that one of'the arms engages the first contact of the series upon the first step that the switch takes from its normal position. and disengages the last contact of the series upon the last step which the switch takes.

The impulses that are applied to the number indicating device through the medium of the impulse sending switch 620. are produced by an identifying interrupter 640 (see Fig. This interrupting device comprises commutators 641 to 650, inclusive, that are arranged to produce from one to ten interruptions, respectively and consequently from one to ten impulses of current for each cycle of rotation. The interrupter 640 also is provided with a pieleup commutator 651 and a slip-ring 652,the pick-up commutator being geared to rotate once for each five rotations of the commutators 641 to 650 inclusive. To

simplify the drawing, certain of the commutators of the interrupter 640 are re resented at different points in the drawing circles with included numerals indicating t e number of impulses of current produced by the commutator for each revolution.

An impulse selecting commutator controlled in accordance with the movement of the line finder elevator, and an impulse selecting switch controlled in accor ance with the particular set of brushes tripped and made active, operate singly or in conjunction in the selection of impulses for.

designating certain of the digits of the calling subscribers line. The impulse selecting commutator is a part of the line finder switch LF which may be substantially like the switch illustrated and described in latent 1,777,044 to James L. McQuarrie, issued March 28, 1916. The structural arrangement of this switch is generally shown in Fig. 5, which illustrates diagrammatically portions of two of the brush carrying elevators and associated banks of multiple line terminals of the panel type switch of the McQuarrie patent. Each finder switch'comprises a longitudinally mova'ble shaft 1, carrying as many sets of brushes 2 as there are groups of stationary line terminals to be engaged, and in addition an impulse selecting commutator consisting ofa set of tionary terminals comprising three vertical rows T, T and U, with as many terminals in each row as there are sets of termi-,

7 through the medium of an extension at the lower end of the shaft, which is brought into engagement with the constantly rotating power member 3 by means of an idler wheel operated by the lip-drive magnet 32; and the brush-carrying shaft is moved down by means of a reversely rotating power member 4 with which the 'extension of the shaft is brought into engagement by means of an idler wheel 0 )erated by the downdrive magnet 62. ormally each of the brushes of each of the sets 2 are held apart so as to clear the associated terminals by means of a separating cam 5 located between the innermost brushes of the set. The cam 5 is rotatably mounted, and when rotated'in one direction, releases the brushes and permits them to engage the associated line terminals. The brushes of the set 2' are fixedly mounted so as to engage the terminals in the rows T, T and U of the associated contact bank as thebrush-carrying shaft moves up and down. The tripping sets 2 is controlled by anumber of tripping magnets 17-1 to 17-10 inclusive. Each of these magnets when energized rotates an associatedtrip rod 6 that extends transversely of the switch shafts 1 and carries as many tripping yokes 7 as there are finder switch elevators in the group. The trippin rod in rotating brings al of its trip yo es 7 into position to operate the brush-controlling cams 5 of the corresponding sets of brushes on all of the switches, so that whichever of the. finder switches is caused to move up, has that set of brushes tripped that corresponds with the particular trip magnet 17-1 to 17-10thatis atthe time energized. Whenthe finder switch that has been in use is returned to its normal position, any of the associated controlseparate its switch spring? again and thusrender them inactive. ch of the line finder elevators also has associated with it a commutator 8 which comprises a number of stationary commutator segments, and a set of mova le brushes carried at the top of stationary segments. his commutator serves to make and break a number of the controlling circuits in the various stages of the movement of the switch shaft.

The stationary contacts engaged by the set of brushes 2 of the impulse selecting commutator correspond in number and loswitch shaft 1 and coii crating with the I cation to the stationary contacts of each of the line groups, so that in an position to WhlCh the elevator is moved, t e brushes of the set 2' are in en agement with contact terminals corres on ing in position to the contact termina s simultaneously enga ed by. the active set of line brushes 2. i he terminals of the rows T T andU are permanently connected with the various commutators of the interrupting device 640. The first ten contacts of the row T are multiply .connected to commutator 650.

which supplies ten impulses of current during each rotation of the interrupter 640; the next ten terminals of row T are multiply connected to the commutator 641 which supplies one impulse of current during each rotation of the interrupter; similarly, successive series of ten contacts in the row-T are multiply connected to

commutators

642, 643 and 644 which supply two, three and four impulses of current, respectively, in each rotation and successive series of ten contacts in the row T are multiply connected to the

commutators

645, 646, 647, 648 and 649 which supplyfive, six, seven, eight and nine impulses, respectively in each rotation of the interrupter 640. Obviously in the rows T and T each multiply connected series of ten contacts may be replaced by a single contact of a length equal to the combined length in the row of the ten individual contacts of the corresponding series. In the row ll of stationary contacts, every tenth contact is multiply connected to the same commutator of the interrupter 640, the lowest contact of the row and the five other contacts to which it is multiply" joined being connected with commutator 650 which delivers ten impulses per revolution, the second contact" from the bottom and its multiply co nnected contacts being connected with commutator 641 which delivers one impulse of current per revolution, and so on through the multiply connected series of contacts in the row. Each of the five series of ten contacts each, into which the row U is thus divided, is therefore arranged to deliver from one to ten impulses of current to the. cooperating brush, depending upon the particular con; tact of the series with which the brush is in engagement. The U row and brush of the impulse selecting commutator control the selection of the impulses for designating the units digit of the calling line. The T and T rows and their associated brushes, in conjunction with the impulse selecting switch, control the selection of the impulses 'for designating the tens digits of the calling line. The impulse selecting switch alone controls the selection of the impulses for designating the hundreds digit of the calling line. i

This impulse selecting switch of which there is one for each finder circuit, may be a sequence switch 600, the extent of movement of which may be controlled in accord ance with the group in which the calling line is. located, and consequently the set of brushes that is tripped. The sequence switch 600 is adapted'to be moved'to and to rest in any one often impulse selecting positions, these being positions 2 to 11 inclusive. The movement of the impulse selecting sequence switch 600 of whichever finder circuit is extendedto a calling line, is under the control of the ten relays 16-1 to 16-10, inclusive, one being provided for each of the ten groups of lines and being energized in the energization of the associated brush tripping magnetof that group. When any one of these relays 16-1 to 1610 inclusive is operated, it closes an energizing circuit for the motor magnet of the sequence switch 600, and also closes a locking circuit for itself which is controlled in contacts of the sequence switch 600. The locking circuit of relay 16-1 of the first group of lines is completed through contacts of the sequence switch 600 that are closed until sequence switch 600 passes beyond position 1.; of its movement, the sequence switch thus coming to rest in position 2. The locking circuit of relay 162 associated with the sectin ther contacts of the sequence switch 600 control the impulses applied by the impulse sending switch 620 in its hundreds sending position. Thus in

positions

2 and 3 of sequenceswitch 600, to one of which ositions the switch is moved when 'any line in the first two groups including lines 0 to 99 calls, the sequence switch connects the hundreds contact terminal 622 of the impulse sending switch 620 to the commutator of interrupter 640 that supplies ten impulses of current, adapted to dlsplay the 0 lamp of the number indicating device 700. In

positions

4 and 5, to one of which the switch is moved when any line in the third and fourth groups, including lines 100 to 199, calls, the sequence switch connects the hundreds contact terminal of impulse sending. switch 620 to the commutatorthat supplies one impulse of current to the number indicating device 700. In like manner in position 6 and 7, corresponding to a call in the two groups including lines 200 to 299, sequence switch 600 connects the hundreds contact of switch 620 to the commutator that supplies two impulses of current; in

positions

8 and 9, corresponding to a call in the two groupsincluding lines 300 to 399, it connects the hundreds contactto the commutator supplying three impulses'of current; and in positions 10 and 11, corresponding to a call in the two groups including lines 400 to 499, it connects the hundreds contact to the commutator supplyingfour impulses of current. The above is on the assumption that the 500 lines served by the finder switch are the first five hundred lines of the thousand,that is, lines 0 to 499. If the lines served are the second five hundred lines of the thousand, that is, lines 500 to 999, then the contacts of the sequence switch 600 are so connected as to apply five, six, seven, eight or nine impulses of current to the hundreds contact of the impulse sending switch 620, depending upon whether the sequence switch has been moved to its 2 or 3, its 4 or 5, its 6. or 7, its 8 or 9, or its- 10 or 11 position. a

Still other contacts of the impulse selecting sequence switch 600 coiiperate in the control of the impulses applied by the impul sending switch 620 in its tens sending posi ion. the first, third, fifth, seventh and ninth roups of contacts of the finder switch are ale first fifty. lines of their respective hundreds in each case, their tens digits are 0, 1, 2, 3 and 4, respectively; and as the lines that terminate on the second, fourth, sixth, eighth, and tenth groups of contacts of the finder switch are the second fifty lines of their respective hundreds in each case, their tens digits are 5, 6, 7, 8, and 9, respectively. In the movement of the impulse selecting commutator comprising the vertical rows of contacts T, T and U and their correspondnig brushes t, t and u, as has been described, the five grou s of ten contacts each in the vertical row are so connected to the interrupter commutators as to' ap ly ten, one, two, three, and four impu see of current respectively to their associated brush t, and the five groups of ten contacts each in the vertical row T are so connected to the interrupter commutators as to apply five, six, seven, eight and nine impulses of current respectively to their associated brush t. Consequently, the contacts of the impulse selecting sequence switch 600 are so arranged that when the sequence switch has been moved to its 2, 4, 6, 8, or 10 position, as the result of a call in the first fifty lines of any of the hundreds, the tens contact 623 of the impulse sending switch 620 is connected to brush t of the vertical row T, so that ten, one, two, three, or four impulses of current are applied, depending upon the extent of the vertical movement of the line finder elevator; while if the sequence switch has been moved to its 3, 5, 7, 9, or 11 position, as the result of'a call in the second fifty lines of any of the hundreds, the tens contact of the impulse sending switch 620 is connected to brush it of the vertical row T, so that five, six, seven, eight or nine impulses of current are applied, depending upon the extent of the vertical movement of the line finder elevator.

For controlling the circuits of the organization, there are employed a number of sequence switches which are shown at diflerent points and designated 200, 300 and 600, respectively. These se uence switches may be of the type disclose in Patent 1,127,808, issued February 9, 1915, to Reynolds and Baldwin. Each consists of an electro-magnetically controlled motor or driving mechanism and a number of associated switch cams. The switch cams associated with each of the sequence switches 200 are designated As the lines that terminate on switches 600 are designated 601 to 613, in-

clusive To each of the contacts associated with the various sequence switch cams are 'contacts are open; the numerals applied to all of the other contacts of each sequence switch indicate the only ositions of the particular sequence switch 1n which the associated contacts are closed.

The manner in which the line identifying devices cooperate with each other and with the associated parts of the organization in a telephone call distributing system to perform their functions will be fully explained in the detailed description that follows. It will be assumed that the directory number of station A is 8301, and that the subscriber at-this station, in initiating a call for another subscribers station, takes his telephone receiver from its hook. The

brushes

131, 132 and 133 of the distributer switch 130 are fixedly mounted on a common shaft that is driven by a suitable source of power, and are constantly rotating. They are thus successively bringing the cut-in relay 11. and the test relay 12 into momentary association with the various lines of the line group LG which the distributer switch 130 serves, and in which the calling line 8301 is included. If a line is in use either as a calling line or as a called line, its sleeve conductor 53 is connected through relatively low resistance with battery of the same potential as that to which the winding of the cut-in relay 11 is connected, as will hereinafter be explained. Consequently, when the distributer brush 133 engages the sleeve terminal of such a line, the cut-in relay 11 remains inert. tributer brush 133 engages the sleeve terminal of a line that is not in use, an energizing path is closed for the cut-in relay 11 by way of the brush 133 and the sleeve resistance 91. The test relay 12, therefore, is connected with the two

line conductors

38 and 39 of each line that is not in use, and when it is thus connected with the-conductors of the line extending to station A (line number 8301) at which the telephone receiver has been removed from its switch hook, the. test relay 12 attracts its armature and closes a circuit that extends from battery through the winding of relay 9 to ground by' way of the front contact and But when the disarmature of relay 12. Relay 9 in operating closes a locking circuit for itself by way of its left-hand armature and contact, and the left-hand armature and back contact of relay 10. The distributer brushes do not stop upon the terminals of the calling line, but continue their rotation, the result of their engagement with the calling line terminals being in effect to record'the call by energizing and locking up the relay 9.

The effect of recording the call upon the relay 9 is to cause the starting of oneof the finder switches LF which serve the lines of this and the associated line groups. This is accomplished through the medium of a starting circuit, two of the

conductors

57 and 58 of which are extended to the relays 19 of the various line groups LG, LG", etc.

Assumim that the startin circuit is not in use at the time the call is recorded on the relay 9 of the line group LG the operation of this relay closes a circuit that extends from battery through the left-hand armature and back contact of relay 23, up per back contact and armature of relay 634:, right-hand armature and back contact of relay 24, conductor 57, right-hand resting contact and switch spring of relay 19 of group LGQthe windings of relay 19 and the associated trip magnet 177 and relay 167 in parallel, left-hand switch spring and resting contact of relay 19, right-hand winding of relay 18, and right-hand front contact and armature of relay 9 to ground. The closure of this circuit causes relay 18 to operate; and in operating, relay 18 closes at its left-hand front contact and armature ashunt path by way of its left-hand low resistance winding to ground that sufficiently lncreases the current flow 1n the circuit to bring about the operation of the relay 19 and its associated trip magnet 177 'and relay 16-7, the relatively high resistance of the'right-hand winding of the relay 18 preventing the relay 19 and its associated trip magnet and relay from being operated at the initial closure of the circuit. -Relay 19 in operating closes a circuit that extends from battery by way of the left-hand armature and back contact'of relay 23, upper back contactand armature of relay 634, winding of the starting relay 24, conductor 58, the right-hand armatures and resting contacts of other relays 19 in the series, right-hand armature and switch spring of the relay 19 of group LG the windings of relay 19 and associated trip magnet 17-7 and relay 16'7 in parallel, and the left-v hand switch spring and armature of relay 19 to ground. The closure of this circuit operates relay 2% and the trip magnet 17-7 of line group LG to start a line finder switch LF, and to trip the brushes of that switch which correspond with the line group in which the calling line is located; and also operates the associated relay 16-7 to control the movement of the impulse selecting sequence switch 600 of the finder circuit, all as will hereinafter be described. This circuit is maintained and the trip magnet l7-7, associated relay 167, starting relay 24' and group relay 19 held energized until the relay .23 1s actuated at a later stage of the operation, as will be described.

When the recorded call has thus brought about the energization of the starting and brush-tripping circuit, the call recording apparatus, including the

relays

18, 9 and 10, is disconnected from the starting circuit and the record obliterated by the releasing and return of these relays to their normal condition. When the recording apparatus obtains access to'the starting circuit, the operation of the relay 18 not only brings about the energization of the start ing and tripping circuit, by closing at its left-hand front contact and armature the low resistance path to ground; but it also closes a circuit that extends from battery through the winding of relay 10, and the right-hand front contact and armature .of relay 18 to ground. The closure of this circuit causes relay 10 to open, at its lefthand back contact and armature, the looking circuit of the relay 9. Relay 9 in releasing opens at its right-hand front contact and armature, the path to ground by way of the right-hand or high resistance winding of the relay 18. As relay 19 in operating has opened at its left switch spring and resting contact, the main energizing circuit of the relay 18, relay 18 therefore releases, and in doing so opens at its righthand front contact and armature the energizing circuit of the relay 10, which relay thereupon releases. Thus the

relays

18, 9 and 10 of the recording apparatus are returned to normal and are in readiness to reslpond to another calling line.

. s has been described, the appropriation of the starting circuit by an incoming call is accompanied by the operation of the relay 24, and the relay 24 in operating disconnects the conductor 57 from battery. As it is over this path from battery that the initial energization of any of the relays 19 is eifected, the calling lines of the other groups are deprived of control over their associated relays 19, trip magnets 17 and associated relays 16 until'the starting relay 24 is returned to normal and the path to battery closed. If a line in another group, say group LG calls while the relay 24 is serving the calling line of group LG the recording relay 9 of that other group is locked up and holds closed a path to ground from conductor 57, by way of the right hand winding of the associated relay 18, that includes the winding of the associated relay 19, trip magnet 17-4 and relay 16-4 in parallel. When the starting relay 24 has performed-its function in connection with the calling line of group LG and releases its armatures. the relays 23 and 634: also being inert at the time, the ath by way of conductor 57 is completed or the energization of the re cuit that extends from battery by way of the cord selector sequence switch contact 320 (1 to 4) of whichever of the line finder switches LF is next in order to be started, winding of relay 30, selector sequence switch contact 309 (1 to 7), finder sequence switch contact 217 (2), and thence to ground by way of conductor 29 and the left hand armature and front contact of starting relay 24. Relay 30 in operating closes a circuit that extends from battery through the motor magnet and contact 203 (2) of the finder sequence switch, and right-hand front contact and armature of relay 30 to ground. The closure of this circuit moves the finder sequence switch 200 out of position 2. Relay 30 in operating also closes a locking circuit for itself that extends from battery by way of selector sequence switch contact 320 (1 to 4), winding of relay 30, selector sequence switch contact 309 (1 to 7 left-hand front contact and armature of relay 30, selector sequence switch contact 317 (1), finder switch sequence contact 216 (2 to 4), conductor 25,'and the right hand back contact and armature of relay 23 to ground. When the finder sequence switch moves from position 2 to position 3, it closes a circuit from battery through the winding of up drive magnet 32, conductor 59, finder sequence switch contact 213 (3 to 4) and the right-hand back contact and armature of test relay 37 to ground, that starts the upward movement of the elevator shaft 1 carrying the sets of brushes;

The test relay 37 is energized to open the circuit of the up-drive magnet 32 and stop the'upwardmovement of the finder switch brushes when the terminals of the calling line are engaged, as will hereinafter be described.

At the outset of the upward movement of the elevator shaft 1 of the line finder switch, as a result of the energization of the updrive magnet 32, all of the brush trip levers are moved past their corresponding trip yokes 7 (see Fig. 5). The only trip magnet that is in its energized condition in this case is the magnet 17-7 which corresponds with the group LG7 in which the calling line'is assumed to be located; and consequently the only trip yoke in position to engage a trip lever on the elevator shaft is the one which controls the brushes 4.0, 41, 42

and 43 that are adapted to engage the termi-- nals of that particular group of lines. This set of brushes, therefore, is released and made 0 rative, and the other sets are held clear 0 their associated line terminals.

At the same time that the trip magnet 17-7 is energized to determine the tripping of'the corresponding set of brushes, the associated relay 16-7 is ener 'zed to determine the settin that the impu se controlling sequence swltch 600'shall take. When the relay 16-7 is operated by the flow of current through its right-hand winding that occurs when the relay 19 of the corresponding group operates, and when, an instant later a finder circuit has been set in operation to take the call, a circuit is closed that extends from battery through the left-hand winding and the inner front contact andarmature of relay 16-7, conductor 666, multiple branch to contact 610 (1 to 7 4) of the impulse select-- ing sequence switch of the chosen finder circuit, and to ground by way of contact 225 (3) of the finder sequence switch 200. This locking circuit of relay 16-7 is thus maintained subject. to the control of the impulse selecting sequence switch 600. When relay 167 operates it also closes a circuit that extends from battery through the motor magnet of the impulse selecting sequence switch of the chosen finder circuit, finder sequence switch contact 222 (3), conductor 638, outer front contact and armature of the operated relay 16-7, through the back contacts and armatures of the other relays 16 preceding the relay 16-7 in the series, conductor 636, and finder se uence switch contact 225 to ground. e closure of this circuit energizes the motor magnet of sequence switch 600, and causes that sequence switch to rotate until its energizing circuit is opened: The opening of the circuit occurs when the relay 16-7 becomes deenergized, and this takes place when the locking circuit of relay 16-7 by way of the left-hand winding of the relay is interrupted at contact 610 (lto 7%) of the impulse selecting sequence switch, this occuring when sequence switch 600 has moved beyond position 7%.

The impulse selecting sequence switch therefore stops in position 8', in which position the hundreds contact 622 of the impulse sending switch 620 is connected, by way of sequence switch contact 607 (8 to 9), with the commutator of interrupter 640 that delivers three imgulses of current in each cycle of rotation; s position 8 of the sequence switch 600 is one of the even numbered positions in which the switch is adapted to rest, the tens contact 623 of the impulse sending switch 620 is connected b way of thesequence switch contact 605 8) and conductor 653 with brush t that coiiperates with the vertical Tow T of the impulse selecting commutator. As will subsequently be described, the line finder elevator, in connecting with l the calling line, which is assumed to be line number 8301, is stop )ed' on the second set of terminals of the fi y sets in the bank on which the calling line terminates. Therefore brush t is sto bed on the second terminal in the vertical row T, which terminal, together with the nine other terminals of the first ten in the row, is connected with the commutator of interrupter 640 which delivers ten impulses of current per cycle; and consequently this commutator is connected to the tens terminal of theimpulse sending switch 620.

As soon as the set of brushes corresponding with the group in which the calling line is located in tripped, the trip magnet l7--7 and the relay 19 of this group and the common starting relay 24 are released. The release of the trip magnet and its associated group relay 19 and the starting relay 24 is effected by the closure of a circuit which extends from battery by way of the windl mg of relay 23, conductor 26, finder sequence switch contact 212 (3 to 4), conductor 68, and segment (ir of the line finder commutator and its corresponding brush to ground. As a result of the closure of this circuit, which is timed to occur aninstant after the brushes are tripped and before they engage the line terminals in the upward movement of the elevator shaft, relay 23 is energized to open, at its left-hand armature and back contact, the circuit by way of conductor 58 that up to this time has been holdin the starting relay 24, the trip magnet 17- and the associated relay 19 energized. The relay 23 in operating also closes at its righthand armature and front contact an energizing circuit for the relay 634, and this relay at its upper armature and back contact introduces another break into the circuit that supplies battery to the starting relay 24, group relay 19 and trip magnet 17--7, and also closes at its lower front contact and armature a locking circuit for itself that extends by way of conductor 635 and finder sequence switch ,contact 226 to ground. This insures the maintaining 1noperative of the starting relay 24 and the relays 19 and 16, and the trip magnet 17 of the other groups until the sequence switch 200 of the seized finder circuit moves out of position 3.

When relay 23 operates, 1n responseto the grounding of the G segment of the line finder switch commutator, it also interrupts at its right hand armature and back contact the previously tracedcircuit that has maintained relay 30 of the finder circuit energized. That relay, in releasing its armatures, closes a circuit for moving the finder sequence switch 200 of some other finder circuit from its normal or first position to position 2, where it is in readiness to respond to the next operation of the starting relay 24. Assuming that the finder circuit F, which ma be assumed to be similar to the finder circuit F in its equi ment, has its parts in their normal conit1on, this circuit may be traced from battery through the motor magnet 200 and contact 204 (1) of the finder circuit F, finder sequence switch contacts 204 (5 to 18) of other finder circuits similar to the circuits F and F1 in their equipment, which finder circuits may be assumed to be busy, and 7 therefore to have their sequence switches in some position between position 5 and position 18 inclusive, finder sequence switch contact 221 (3 to 4) of finder circuit F, lefthand back contact and armature of relay 30, selector sequence switch contact317 (1 finder sequence switch contact 216 (2 to 4 conductor 25, and right-hand back contact and armature of relay 23 to ground.

Thus the passing of the G segment in the upward movement of the started finder switch releases the group and starting relays and trip ma net, releases relay 30 oi? the associated fin er circuit, and moves sequence switch 200 of another finder circuit 1nto position 2 in readiness to respond to the next actuation of the starting relay 24 as soon as the starting circuit is again made effective by the movement of the first finder sequence switch out of position 3 and the release of relay 634.

if] hen the impulse selectin sequence switch 600 moves beyond positlon 71]; and opens the locking circuit of 16-7, as previously described, that relay not only opens the energizing circuit at the sequence switch and stops the movement of the switch, but 1t also closes at its outer armature and back contact a circuit that extends from battery through the motor magnet and contact 224 of the finder sequence switch, conductor 637, the back contacts and armatures of all of the 16 relays in series, including the back contact and armature of relay 167 just released, conductor 636, and finder seuence switch contact 225 (3) to ground.

he closure of this circuit moves the finder sequence switch out of position 3, the switch coming to rest in position 4. This movement of the finder sequence switch out of position 3, which occurs when the impulse selecting sequence switch has completed its registration of the calling line group, breaks the locking circuit of relay 634 and releases that relay, thus rendering the starting circuit again available for the use of another calling line.

The condition that is now assumed to exist is one in which the line finder switch LF' is moving up with its set .of brushes tripped corresponding with .line group LG, in which the impulse selecting sequence switch 600 has been moved to position 8, corresponding with the group in which the calling line is located, and in which the finder sequence switch of another finder circuit F has been moved to-position 2 in readiness to respond to the next operation of the starting relay. As the tripped brushes rise, they come 1nto enga ement consecutively with the sets of terminals corresponding with. the different lines of the group). At the instant of engagementof the rush 42 with the correspondin terminal 46 of each line, a clrcult is close that extends from battery by wav of relay 52 (see Fig} 3), sequence swltc contact 209 (2 to 4), conductor 50, brush 42, line terminal 46 conductor 53, and reslstance 91 to ground. ln case a line is busy, either as a calling line or as called l1ne, a path to battery extends from conductor 53, as

' will hereinafter a pear that serves to shunt the relatively hig res1stance relay 52 and prevent its operation. If a line over the terminals of which the brushes are passing is not busy, the relay 52 is operated, and in attracting its armatures closes a circuit that extends from battery through the left-hand Winding of the relay 37, inner armature and front contact of relay 52, sequence switch contact 208 (2 to 4), line terminal 45, conductor 39 to one limb of the telephone line, thence by Way of the path controlled in contacts of the substation switch hook to the other limb of the line, conductor 38, terminal 44, brush 40, conductor 48, sequence switch contact 207 (2 to 4), outer front contact and armature of the relay 52, and righthand winding of the relay 37 to ground. The circuit traced above is not completed until the finder switch brushes engage the 4 terminalsof the calling line, as the calling line is the only line that has its telephone receiver off the hook, and at the same time is not connected with either by some other line finder or by a connecting circuit calling plug. The completion of this circuit energizes the relay 37 and causes that relay to interrupt at its left-hand back contact, the

circuit, by way of the finder sequence switch contact 213 (3 to 4) and conductor 59, which up to this time has been keeping the updrive magnet 32 energized to cause the upward movement'of the switch brushes therefore the operation of the relay 37 u on the finding of the calling line acts to e ect the instant deenergization of the updrive magnet 32 and thus to stop the line brushes on the terminals of the calling line and the brushes t, t and u upon corresponding terminals of the impulse selecting commuv tator.

Relay 37, in operating, also closes a locking circuit for itself by way of its left-hand front contact and armature and 'finder sequence switch contact 219 (3 to 4) to ground. It also completes a circuit that extends from battery through the motor magnet and contact 206 (4) of the finder sequence switch,

.scribers line.

brushes of a switc and right-hand front contact and armature of relay 37 to ground. a If the impulse selecting sequence switch 600 has completed its registration of the callin line group, and t 1e consequent release 0 relay 16-7 has moved thefinder sequence switch 200 out of position 3, as previously described the closure of the circuit at the right-ban front contact and armature .of relay 37 moves the finder sequence switch out of position 4. But if the line brushes of the line finder switch reach the terminals of the calling line before the group registration on the impulse selecting sequence switch 600 is completed, then the circuit closed by way of the right-hand front contact and armature of relay 37 remains in readiness to move the finder sequence switch out of position 4 as soon .as the com letion of the grou registration moves the nder sequence switcli out of position 3.

When the finder sequence switch moves to position 5 sea result of the finding of the callin line, it closes-a circuit that extends from attery by way of resistance coil 54 and sequence switch contact 210 (5 to 5%), the sleeve conductor 50 of the finder circuit, and thence by Way of the finder switch to the'sleeve conductor 53 of the ca ing sub- This creates an electrical con dition upon the line that prevents it thereafter from afl'ecting the distributer test magnets 11 and 12, and that prevents it from being connected with by any other line. In moving to position 5, the finder sequence switch also closes a circuit that extends from battery through the motor magnet and contact 302 (-1) of the selector'sequence switch, contact 220 (5) of the finder sequence switch, and right-hand back contact and armature of relay 37 to ground, the relay 37 having been released by the breaking of its locking circuit when the finder sequence switch moves out of position 4'. The closure of this circuit moves the selector sequence switch out of position 1 and into osition 2.

. After the calling line has een extended to a finder circuit, in the manner described in the fore oing, the finder circuit is extended to an id e connectin circuit'or cord on an operators position, t at is at the time available for handlin the call and com leting the connection 0 the'calling line wlth the calledline. The precise manner in which the finder circuit is extended to an operators connecting cord is immaterial to the present invention, and may be accomplished in any one of a number of well-known ways. In the present instance, the finder circuit is illustrated as extending in vfour conductors, 96, 97, 98, and 99 to four corresponding 1 CS'which may be the cord selector switch of the reviously mentioned ap lication Serial umber 229,035, (08.5036, filed A ril 17,1918, by s. B.

Williams, Jr. The four brushes of the cord selector switch are adapted to extend the finder circuit to a cord circuit CO by their engagement with the

terminals

115, 116, 117 and 118 of that cord circuit. There ma be a plurality of such cord circuits, and t ese cord circuits may terminate at a plurality of operators positions. The apparatus shown associated with the right-hand half of the finder circuit corresponds with a part of the finder circuit apparatus of the above mentioned application of S. B. Williams, Jr.; but only as much of the apparatus is here shown as is required to indicate the connection of the finder circuit conductors with the connecting cord circuit through the medium of the selecting switch CS. The selector se uence switch 300 has an energizing circuit w ereby it may be moved from one to another of its operating positions. WVhen it arrives in position 7, the brushes of the cord selecting switch CS are ,in engagement with the terminals of the selected cord, and a circuit is closed that extends from battery by way of selector sequence switch contact 320 (7 to 11), winding of relay 30, selector sequence switch contact 305 (7 to 7%), conductor 99, brush 114 and contact 118 of selector switch CS, and closed contact 413 to ground. Relay 30, in operating, closes a circuit that extends from battery through the motor magnet and contact 302 (6 to 8) of the selector sequence switch, and right-hand front contact and armature of relay 30 to ground. This moves the selector sequence switch out of position 7 and into position 8. In moving out of position 7 the energizing circuit of relay 30, traced above, is broken at selector sequence switch contact 305 (7 to 7%), and relay 30 consequently releases its armatures. The movement of the selector sequence switch out of position 7 also breaks a locking circuit for relay 30, which was completed when that relay operated, by way of selector sequence switch contact 309 (1 to 7 ),-left-hand front contact and armature of relay 30, and selector sequence switch contact 310 (7) to ground.

\Vhen the selector sequence switch moves into position 8, the impulse sending switch 620 associated with the finder circuit is connected with the number indicating device 700 associated with the connecting cord circuit, and the impulses that have been predetermined by the operation of the finder circuit mechanism are transmitted to the number indicating device to cause that device to display signals before the operator informingher of the number and class of service of the calling line. The closure of the impulse transmitting circuit is under the control of the pick-up commutator of the interrupter, the arrangement being such that the circuit may be closed only at the beginning of a series of cycles of rotation of the interrupter in order that the trains of impulses that are transmitted may not be mutilated. The extension of the finder circuit to the connecting cord circuit is accompanied by the closure of the

contacts

408, 411 and 416. At the beginning of the first cycle of rotation of the interrupter 640, after these contacts are closed, a circuit is completed that extends from battery through the winding of relay 129, the upper back contact and armature of relay 155, contact 416, and pick-up commutator 651 to ground. Relay 129 attracts its armature and closes a path to ground by way of the winding of relay 155 and contact 411. While the path to ground by way of the pick-up interrupter 651 is closed, the path to ground by way of the relay 155 is short circuited. But an instant later, when the brush and conducting segment of the pick-up interrupter 651 break contact, the relay 155 is energized by the current that flows through it by way of the winding of relay 129, this current also serving to lock up the relay 129. The relay 156 has been energized, by way of the upper back contact and armature of relay 157 and closed contact 411, by the extension of the finder circuit to the cord circuit. Therefore, when the relay 155 attracts its armatures, immediately upon the breaking of circuit through the pick-up interrupter 651, a circuit is closed that extends from battery through the quick-acting rotary magnet 705, the slow-releasing vertical magnet 704, and the resting contact and switch spring 706 of the number indicating device, lower front contact and armature of relay 155, front contact and armature of relay 156, closed contact 408, terminal 118 and corresponding brush 114 of the cord selector, selector sequence switch contact 305 (8 to 9), stepping magnet 630 of the impulse sending switch 620, arm 626 and thousands contact 621 of that switch, contact 608 (2 to 11) of the impulse selecting sequence switch, and the eight impulse per cycle commutator (648) ofthe interrupter 640 to ground. It will be observed that the conducting segments of all of the impulse transmitting commutators of the interrupter 640, with which the respective brushes are in engagement at the start of each cycle of rotation. are relatively long segments. Therefore, the current that flows over the path just traced is of sufficient duration to cause the slow-acting magnets 630 of the impulse sending switch 620 and 7040f the number indicating device 700 to attract their armatures.

Having attracted their armatures, the slow acting magnets 630 and 704 hold them attracted during the series of short interruptions of the circuit which follow, and release them only upon the relatively long break in the circuit at the end of the cycle. But the quick acting rotar magnet 705 of the number indicating devlce, attracts its armature at each make and releases it at each break of the circuit; and each time the armature of the magnet is released, the pawl 708, acting through the medium of the cylindrical ratchet 709, moves the arm with which the pawl 737 is in engagement on step ahead. Each step that an arm takes is retained by the corresponding holding

pawl

722, 720, 718, 716, or 713, these pawls ,being dropped into engagement w th the ratchet wheels, carried on the respective arms by, the energization of the release magnet 715 as a result of the closure of the circuit of this magnet at contact 411. As the circuit at present in question is opened and closed eight times in a single cycle of rotation of the commutator 648 the arm 721 which the rotary stepping pawl engages, will be advanced to the eighth contact of the lower row of contacts The last interruption of the circuit effected by commutator 648 is long enough to permit the slow releasing magnets 630 of the impulse sending switch and 7 04 of the number indicatin device to release their armatures. agnet 630, in releasing, moves the arm 626 into engagement with the hundreds contact 622, and the arm 627 into engagement with'the first of a series of grounded contacts 628. Magnet 704 of the number indicating switch in releasing raises the shaft 710 vertically one step,thus moving the pawl 737 out of engagement with the first arm 721 and into engagement with the second arm 719 of the series. At the same time the latch, dependin from the armature of the magnet 704, li s the pawl 740 from the cylindrical ratchet 709 and permits the shaft 710 to turn back to normal. This places the number indicating device- 700 in position to move the second arm 719 over its row of contacts in accordance with the number of impulses in the second train that is received.

As the impulse sending switch 620 has brought its arm 626 into engagement with contact 622, the energizing circuit for the rotary magnet 705, and vertical magnet. 7 04 I of the indicating device, and the stepping magnet 630 of the impulse sending switch in series is now completed, underthe assumption that it is line 8301 that is calling, by way ofarm 626, contact 622, contact 607 (8 to '9) of the impulse selectin sequence switch and to ground by way 0 the commutator of interrupter 640 that makes and breaks the circuit three times in one cycle of rotation. The three interruptions of the circuit cause arm 719 of the number indicating device to be advanced to the third contact of the second row; and as a result of the relatively long duration of the third or last interruption, magnet 704 of the indicating device releases its armature and raises the shaft 710 another step to bring the pawl 737 into operative relation with the third arm 717:, and the stepping magnet 630 of the impulse sending switch releases its armature and thereby advances the arm 626 another step to bring it into engagement with the contact 623.

This closes the operating circuit of the number indicating device 700 and the impulse sending device 620 to ground My way of arm 626, contact 623, contact 605 (8) of the impulse selecting sequence switch, cond tor 653, brush t, the second contact of 135v T, and commutator 650 which is adapted to make and break the circuit ten times in one cycle of rotation of the interrupter. As a result of the ten breaks in the circuit, arm 717 of the number indicating device is advanced to the tenth or naught contact of its row; and as the last break is a long one, the magnet 704 releases to elevate the shaft 710 another step, thus placing the fourth arm 712 in operative relation with the rotary magnet 705, and magnet 630 of the impulse sending device releases to move arm 626 into engagement with contact 624. This completes the operating circuit of the indicating device 700 and the impulse sending switch 620 to groundby way of arm 626, contact 624, contact 604 (2 to 11) of the impulse selecting sequence switch, conductor 655, brush u, the second contact of the corresponding row U, and commutator 641, which is adapted to make and break the circuit once per revolution. The single long make energizes

magnets

705 and 704 of the number indicating device and magnet 630 of the impulse sending switch; and the relatively protracted break which follows, releases all three magnets, the release of magnet 705, advancing arm 712, into engagement with the first contact of its row, and the slower release of magnets 704 and 630, respectively, elevating the shaft 710 another step to bring arm 711 into operative relation with the rotary magnet 705, and advancing arm 626 of the impulse sending switch 620 into engagement with contact 625,

This completes the operating circuit of the indicating device 700 vand the impulse sending switch 620 by Way of arm 626, contact 625, contact 318 (8 to 9) and (8 to 11) of the selector sequence switch, conductor 51, brush 43 and corresponding contact 47 of the finder switch LF, conductor 54 of calling line 8301 and to' ground by way of the commutator of interrupter 640, that is adapted to make and break the circuit four times per revolution. Consequently the rotary magnet 705 of the indicating device extends from battery through the motor magnet and contact 304 (9) of the selector sequence switch, and right-hand back contact and armature of relay 30 to ground. The closure of this circuit moves the selector sequence switch out of position 9 andinto position 10.

In position 10 of the selector sequence switch, a circuit is closed that extends from battery through the motor magnet and contact 202 (5) of the finder sequence switch, and contact 310 (10) of the selector sequence switch to ground. When the finder sequence switch moves out of position 5 and into position 6, as a result of the closure of this circuit, it completes, at its contacts 207 (5% to 6) and 208 (5% to 6), the talking conductors of the finder circuit. When the selector sequence switch moves into position 10, it also closes a circuit that extends from battery through the winding of relay 13 (see Fig. 4), contact 412 and rontcontact and armature of relay 13 in parallel,

the contact 412 having been closed when the finder circuit was first extended to the connecting cord circuit, closed contact 81, contact 117 and brush 113 of the cord selecting switch CS, conductor 98, selector sequence switch contact 307 (10 to 11), left-hand winding of relay 56, selector sequence switch contact 306 (8 to 11) finder sequence switch contact 209 (5%- to 6), conductor 50, thence by way of the finder switch to conductor 53 of the calling line, and to ground through resistance 91. When relay 56 operates, as a result of the closure of this circuit, it closes a circuit that extends from battery through selector sequence switch contact 320 (7 to 11), winding of relay 30, selector sequence switch contact 309 (10 to 11), and left-hand switch sprin and armature of relay 56 to ground. elay 30, in operatin closes a circuit that extends from battery t rough the motor magnet and contact 302 (10) of the selector sequence switch, and right-hand front contact and armature of relay 30 to; ground. This moves the selector sequence switch out of position 10 and into position 11, which is the talking position of the switch.

When the operator has obtained from the indicating device 700 the number and class of service of the calling line, the

switches

408, 411 and 416 are opened to disconnect the indicatin device and permit its return to normal. n opening contact 411, the energizing circuit of the release magnet 715 is interrupted. The release ma et, therefore, releases its armature, which acts to withdraw theholding pawl 714 to allow the,

shaft 710 to drop back to normal, and also to withdraw the

pawls

713, 716, 718, 720 and 722 that hold the corresponding switch arms in the positions to which their respective sets of impulses have advanced them. The

ator completes connection with it by inserting the calling plu 334 into the spring jack 339, and operates t e key 330 to apply ringing current from the generator 199. The supervisory relays 331 and 332, in connection with their associated a paratus (notshown), perform their usual unction of informing the operator of the condition of the connection between the two telephone lines. When the disconnect signal is received, the plug 334 is withdrawn from the called line spring 'ack, and the closed con tacts 81 are opened The breaking of these contacts interrupts the flow of current through the relay 56 (see Fig. 4), and that relay in releasing its armatures opens, at its left-hand armature and switch spring, the

energizing circuit for relay 30 that has been maintained during the conversation by way of selector sequence switch contact 309 10 to 11). Relay 30, in releasing, closes a circuit that extends from battery through the motor magnet and contact 304 (ll) of the selector sequence switch, and the right-hand back contact and armature of relay 30 to ground. This moves the selector sequence switch out of position 11.

When the selector sequence switch reaches position 12, it closes a circuit that extends from battery through the motor magnet and contact 202 (6) of thefinder sequence switch, and contact 310 (12 to 17) of the selector sequence switch to ground. As a of position 6 and continues to move until it reaches position 17, at which time a circuit is closed that extends from battery through the winding of the down-drive magnet 62, conductor 60, and finder sequence switch contact 218 (17 to ground. This returns the line finder elevator to normal; and when the elevator has reached the limit of its downward movement, a circuit is closed that extends through the motor magnet and contact 203 (17 of the finder sequence switch, conductor 69, and segment Y and corresponding brush of the line finder commutator 'to ground. When the finder sequence switch is moved to position 18 in response to the closure of this circuit, a circuit is closed that extends from battery through the motor magnet and contact 602 (2 to 18) of the impulse Selecting sequence switch 600, and

attracts and releases its armature four times, and advances arm 711 into engagem'ent with the fourth contact of its row.

On the long break which is the last interruption of the series, the signals which have been selected as a result of the operation of the indicating device are displayed, the impulse transmitting switch is moved into normal position in readiness to transmit other sets of impulses, and the talking con dition of the finder circuit'is established, as will now be described. When the vertical v stepping magnet 704 of the indicating device releases at the last long break, it elevates the shaft 710 another step. This causes the top 723 of the shaft to engage and operate the switch springs 7 06 and 7 24. The switch spring 7 06, in operating, interrupts the energizing circuit including the

magnets

704 and 705 so that no more impulses may be transmitted through these magnets until the indicating device is restored at a later stage of the operation. The switch spring 7 24, in operating, closes a circuit that extends from battery in parallel through the various lamps that have been selected, the switch contacts corresponding to these lamps and the associated switch arms, switch spring 724 and its upper contact, and the lower front contact and arma- .ture of relay 157 to ground when this relay operates. The operation of the relay 157 occurs upon the closure of the pick-up commutator 651, which .takes place once in each five revolutions of the interrupter 6 10. When the pick-up commutator closes at the end of the transmission of the train of five groups of impulses, as described, a circuit is completed that extends from battery. through relay 157, upper switch spring and resting contact of that relay, upper front contact and armature of relay 155, closed contact 116, and pick-up commutator 651 to ground. Relay157, in operating, closes at its lower front contact and armature the circuit already traced for the illumination of the selected lamps 735; and also closes a locking circuit for itself by way of its upper switch spring and armature, and closed contact 411 to ground. Relay 157, in operating, also opens at its upper back contact and armature the energizing circuit of the relay 156, so that that relay releases its armature and opens at another point the energizing circuit for the operating magnets of the indicating device, which circuit is also opened at switch spring 706 and resting contact of that device. a

The lamps that are illuminated when the shaft 710 takes its last upward step and the pick-up commutator operates relay 157, are the'eighth lamp of the first row, the third lamp of the second row, the tenth or zero lamp of the third row, the first lamp of the fourth row, and the fourth lamp of appear their respective numbers. Therefore, under the conditions assumed, the number 83014 is displayed before the operator, the first four digits being the number of the calling line and the last digit indicating the class of service of the line. Or, if desired, the class of service may be represented by a letter, or combinations of letters, on the lamp caps of the top row; and if the fourth lamp of the row is the one that is illuminated when the callin line is a message rate line, the letters 1%R may appear on the cap of this lamp.

The effect on the impulse sending switch 620 of the long interruption at the end of the last group of impulses is to cause the stepplng magnet 630 to release its armature and move its switch arms ahead another step. This moves the switch arm 626 that has been active, out of engagement with contact 625, and brings another switch arm 626 into engagement with contact 621. It also moves the switch arm 627 that has been active, out of engagement with the last contact of row 628, and moves another switch arm 627 into position to engage the first contact of row 628 upon the first step that the switch may subsequently take. The impulse sending switch 620 is thus again in its normal position.

When the impulse sending switch took its first step in sending the trains of impulses, as described, it completed a circuit that extended from battery by way of selector sequence switch contact 320 (7 to 11), the selector sequence switch at the time resting in position 8, winding of relay 30, selector sequence switch contact 309 (8 to 9), and arm 627 and the first contact 628 of the associated row to ground. This caused relay 30 to attract its armatures and close a circuit extending from battery through the motor magnet and contact 302 (8) of the selector sequence switch, and right-hand front contact and armature ofrelay 30 to ground. The closure of this circuit moved the selector sequence switch 300 out of position 8 and into position 9. But this movement of the sequence switch did not disturb the circuit over which impulses were being transmitted from the impulse sending switch 620 to the number indicating device 700, because these circuits are closed at

sequence switch contacts

305 and 318 in both positions8 and 9 of the switch. When the impulse sending switch 620 takes its last step, and moves the arm 627 out of engagement with the last grounded contact 628 of the associated row, the energizing circuit of the relay 30 is broken, and that relay, in releasing its armatures, closes a circuit that contact 223 (18) of the finder sequence switch to ground. The closure of this circuit moves the sequence switch 600 out of the position to which it has been advanced in identifying the group of the calling line, and returns it to its 1 or normal position. At that time a circuit is closed that extends from battery through the motor magnet and contact 203 (18) of the finder sequence switch, and contact 603 of the impulse selecting sequence switch to ground. This moves the finder sequence switch out of position 18 and returns it to its normal or 1 position. All of the line connecting apparatus, as well as the line number and class of service identifying apparatus, is thus returned i this is only one of the systems to which the present invention may be applied and in connection with which it may be used, and that many parts of the organization herein disclosed may be modified or may have other parts substituted for them without the exercise of invention in applying the essential features and principles of this invention to some other type of telephone system; and that therefore it is not intended to restrict the scope of the invention as claimed to the precise embodiment that has been described and illustrated. 1

What is claimed is:

1. The combination with a plurality of lines and an extension circuit therefor, of a finder switch for connecting said extension circuit with a calling line, sources of characteristic current, a number indicating device, and switch mechanism associated with said extension circuit and automatically operated to select various of said characteristic currents in accordance with the calling line number, and to successively connect them to said indicating device to cause it to identify the calling line.

2. In a telephone system, the combination with a plurality of telephone lines and an extension circuit therefor, of a finder switch for connecting said extension circuit with a calling line, an indicating device having a plurality of operating stages, sources of characteristic current, means operated in accordance with the movement of said finder switch for selecting characteristic currents, from said sources, and a sending switch associated with said extension circuit having operating stages corresponding with the operating stages of said indicating device, and

adapted to apply a selected characteristic current in each operating stage to cause a characteristic operation of said indicating device in the corresponding stage.

3. The combination with a plurality of lines and an extension circuit therefor, of a finder switch for connecting said extension circuit with a callin line, a sending switch associated with saic extension circuit and having an operating stage for each digit of the calling line number, an indicating device having corresponding operating stages, sources of characteristic current, and means controlled in the operation of said finder switch for selecting characteristic currents in accordance with the digits in the calling line number and connecting the same to said sending switch for application to said indicating device in each corresponding operat-.

ing stage, whereby said device is operated to indicate the number of the calling line.

4. In a telephone system, the combination with a plurality of lines and an extension circuit therefor, of a finder switch, means for moving the same to make connection with a calling line, indicating apparatus associated with said extension circuit, a source of characteristic currents, current selecting mechanism associated with said extension circuit and controlled in accordance with the movement of said finder switch to select certain of said characteristic currents, and a switch associated with said finder switch for combining said selected'currents into a characteristic current train and transmitting said train to said indicating apparatus to operate it to identify the calling line.

5. The combination with a plurality of telephone lines and an extension circuit therefor, of a finder switch for connecting said extension circuit to a calling line, an indicating device adapted to produce signal indications in accordance with the digits of a calling line number, a source of characteristic currents, means controlled in the operation of said finder switch for selecting currents characteristic of the various digits of a calling line number, and a sending switch associated with said extension circuit for successively applying the selected characteristic currents to said indicating device to cause it to indicate the successive digits of the calling line number.

6. In a call distributing system, the combination with a plurality of telephone lines and an extension circuit therefor, of a finder switch for connecting said extension circuit with a callingline, number indicating apparatus, an impulse producing means for supplying groups of different numbers of impulses, impulse selecting switch mechanism associated with said extension circuit and automatically operated in the operation of said finder switch to select groups of impulses corresponding to