US1439124A

US1439124A - Automatic telephone system

Info

Publication number: US1439124A
Authority: US
Inventors: Rodney G Richardson
Original assignee: Individual
Current assignee: Individual
Priority date: 1916-02-14
Filing date: 1920-06-26
Publication date: 1922-12-19
Anticipated expiration: 1939-12-19
Also published as: US1492396A; FR500916A

Description

d Dec. 19, 1922.

3 SHEETSSHEEI I.

[UL/5271b? Dec. 19, 1922. 1,439,124.. R. e. RICHARDSON.

AUTOMATIC TELEPHONE SYSTEM.

QRIGINAL FILED H8. 14, I916. 3 SHEETS-SHEET 2.

[m ay 3 SHEETS-SHEET 3- ORIGINAL FILED FEB-14,1916.

@MV Fain-15g be extended into Patented Dec. 19, 1922.

UNITED STATES PATENT OFFIQE.

RODNEY G. RICHARDSON, OF CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPALTY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed February 14, 1916, Serial No. 78,161. Renewed June 26, 1920. Serial No. 392,042.

To all whom it may concern:

Be it known that I, RODNEY G. RICHARD- soN, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and. useful Improvements in Automatic Telephone Systems, of which the following is a specificationi My invention relates to automatictelephone systems and as to its principal features relates more particularly to such systems as employ so called finder switches for connecting a calling line with a selector or connector switch.

In systems of the above general character the lines are divided into groups, and there is provided for each group of lines a sufi icientnumber of finder switches to handle the maximum number of originating calls from that group. Each finder may be directly connected to a selector or connector switch, depending on the size of the system, through the medium of which a calling line, when located by a finder switch, may connection with a called line.

I am aware that a great many systems employing finder switches operating on the general plan outlined above have been devised before this, but tothe best of my present knowledge these systems are all open to the objection that some of the lines require a very considerable movementof the movable contacts of a finder switch for their location. These lines may not 'always be the same ones, for in some systems the movable contacts or wipers of the finders have no normal position; but whatever the position of the wiperswhen their movement is started, trey must, to reach certain of th lines, move a considerable and almost pro hibitive distance.

This difficulty cannot be absolutely and in. all cases removed, for should there be but one idle finder switch when a call is iniever, to reduce the movement required to locate a calling line sufficiently for all practical purposes by providing that the finder switch wipers shall have no normal position, i. e., they shall remain on the contacts of the line last served; providing further that if a calling line already has in engagement with its contacts the wipers of a finder switch, that this finder shall be used; and by providing finally that if a calling line has no finder switch wipers in engagement with its contacts and there is more than one finder idle that the finder which requires the least movement of its wipers to reach the calling line will be started. In other words, whenever there is more than one finder in a group idle, a calling line will start that idle finder whose wipers, in so far as the possibility of their connecting with-the calling line is concerned, happen to be closest to the contacts of that line.

The principal object of my invention, then, is to provide in a system of the above general character, a suitable and efficient method by which a calling line will be served by that one of a plurality of idle finders Whose wipers require the least movement to reach its contacts.

A further object is to provide in connection with the above, means whereby finder switches in the same group may be started in rapid succession by successively calling lines.

Further objects relate to improvement in circuit arrangement whereby these features are incorporated in a practical and efiicicnt system.

To accomplish the foregoing and other useful ends my invention comprises means which will be hereinafter set forth and claimed, reference being bad to the acconr panying drawings. 7

In the drawings Figures 1 and 2, taken in order with the lines at the ends thereof in alignment, represent diagrammatically a complete circuit connection between a calling substation A and a called substation A, in a system embodying the principles of my invention. The Said connection has been establishcd throughthe medium of the finder switch C, the selector switch I), and the connector switch In Figure 3, I have shown a top View of the mechanism of the finder switch C, while Figure 4: represents a cross-section of Figure 3 on the line a, Z); In Figure 5, I have shown the starting connections and a portion of the banks of three finder switches belonging to the same group. Figure 6 is a schematic representation of .one of the circuits shown in Figure 5.

The substation A (Fig. 1) may be of the 1 ype of substatirm shown in Britpatent to T. U. Martin No. 1411.9 of 1910. herein represented it consists of the receiver 2, transmitter 3, receiver hook 1, ringer 5, and condenser 6. Being an automatic substation it is also provided with p a pair of impulse springs 8 and 9 controlled by the impulse wheel 7, which in turn is controlled through the mediumof a finger hole dial (not shown). The springs and wheel as shown herein may be arranged in the manner shown in British patent to S. G. S. Dicker 29,654 of 1910.

Theline conductors 11 and 12 of the substation A have allotted to them at the exchange the line and cut-off relays 21 and 20; a set of multiple bank contacts in the bank of each finder switch, one of these sets being indicated by reference characters 35-439, inclusive; a pairof contact springs 45 and 46 associated with each set of finder bank contacts; and a set of multiple bank contacts (not shown) in the bank of each connector, such as connector E gFig. 2), which has access to the group of ines of which the line of substation A is one. The normal conductors 13, 14, and 15 extend to the latter sets of bank contacts. The functions ofthe line and cut-off relays are very similar to the usual functions of these relays in other well known systems, although the line relay 21 in my system is somewhat different in o eration as will appear more fully hereina ter. The bank contacts 37. 38, and 39 in the bank of finder switch O are multipled to corresponding contacts in the banks of all other finder switches in the group; each line of the group of which the line of substation A is one, of course, being multipled through the banks of these finders in the same manner. The bank contacts 35 and 36, however, and similar contacts of other lines of the group, are not multipled straight to corresponding contacts in the banks of other finders, as are

contacts

37, 38, and 39, but are connected in a peculiar loop circuit which will be fully explained hereinafter.

The finder switch 6' may be briefly described as a rotary switch whose wipers have a movement in one direction only and have no normal position. Referring to Fig urcs 3 and 4;, the frame of the switch is formed of a circular base plate 200 and a. ring shape-d upper mounting plate 201, the

.' two being separated the proper distai'me and rigidly connected by posts 202, 203. 20 1, and 20;. Supported on bearings in the upper and lower frame plates, is a shaft 206 to which is rigidly secured. an arm 207, a ratchet wheel 210, and five sets of wipers insulated from each other, one set being indicated by reference character A magnet 208,'att ached to base plate 200 by means of the heel piece 209, is adapted, when energiaed, to rotate the shaft 206 through the impulse medium of armature 21.1, pawl 212, and ratchet wheel 2.1.0. The spring 212* tends to hold the pawl 212 constantly in engagement with ratchet wheel 210. The dog 214, which also engages the ratchet wheel 210 serves to prevent backward rotation of the shaft 206.

The various sets of bank contacts are preferably arranged in a complete circle, and

there are shown in Fig. 3 fifty of these sets,

by which it appears that there will be fifty lines in the grou to which the finder switch C has access. he exact number, however, is immaterial, itbeing easily possible and perhaps advisable to increase the number of lines in each group to one hundred. It is understood that the manner in which the finder switch banks and wipers are shown in Figure 1 is purely diagrammatic, the actual construction of these parts being as shown in Fig. 1. In the latter drawing thebank contacts 35-39, inclusive, correspond to the same numbered contacts in Figure 1 and are individual to a certain line. The bank contacts 4044,inclusive, correspond to the wipers 10-44, inclusive,in Figure 1, and are preferably complete circular strips extending around the entire circumference of the bank. Attached to the strips 40'44', inclusive, are conductors which extend to the relays of the switch, shown at C (Fig. 1 It is evident that at all times a certain set of contacts such as contacts 35-39, inclusive, will be connected tothe common strips 10 n inclusive, by means of the five sets'of wipers.

As before mentioned, each set of bank contacts has associated with it a pair of normally closed contact springs, one of these pairs being indicated by reference characters 45 and 46 (Figs. 1 and 4). The arm 207 carries an insulating piece 47 which is adapted to separate the pair of contact springs between which it happens to be resting. Or,- in other words, no matter what set of bank contacts the wipers are resting on, the pair of contact springs associated with that set will be separated by the insulating piece 17.

Referring now to Fig. 5, I have shown diagrammatically therein six sets of bank contacts in each of three finder switch banks, together with six starting wires and their connections in the banks. The six sets of contacts immediately adjacent to the line and cut ofl relays at the left of the drawing are located in the bank of the first finder of the group, finder switch (l; the six sets of contacts at the extreme right of the drawing are located in the bank of the last finder of the group (not shown) while the other six sets of bank contacts are located in the bank of an intermediate finder. It is to be understood that in actual practice there may be more than three finder switches in a group and that each finder, as already explained,

will have fifty or even; one hundred sets of 1 wipers when in motion move. in an upward direction, as represented in Fig. 5.

' The" starting wires are indicated by reference characters 230235, inclusive.? There are as many separate starting wires as there are lines in the group and each starting wire extends from the line relay of. they line with which it' is associated to the starting wire contact of that line in the bank of the first finder switch of the group.- For example, starting wire 232 extendsfroin a contact on the line relay of N0. 3 line to bankcontact 238, in the third set'ofcontacts in. the bani: of the first finder switch; In the same manner, starting 'wire 233 extends from a contact on the line relay of line No. 4: to bank contact 239 in the fourth set of contacts in the bank of the first finder switch. Also, by referring to Figure 1, the starting wire 321 associated with the line of substation A is seen extending from contact 29 on line relay 21 to bank contact 36 in the bank of finder switch C, which is assumed to be the first switch of the group. i

From the foregoing it'will be clear that each line of a group is provided with an individual starting wire extending from its line relay to the bank of the first finder switch in the group. I will now explain how the various starting wires are connected in the banks of the remaining finder switches. Considering the starting wire 280, which is the one associated with line No. 1 (not shown), a complete series circuit which includes eve set of contact SPIlIlgS such as 45 and 46 l igs. 1 and 4:) in every finder switch may be traced as follows: starting wire 230, bank contact 236, contact springs 270 and 271, bank contact 242, bank contact 218 contact springs 272 and 273, bank contact 250, bank contact 252, contact springs 274 and 275', bank contact 253, wire junction 300, and starting wire 231 to bank contact From this point the circuit may be traced. more briefly by way of the second pairs of contact springs of the three finders in series to wire junction 301; thence by way of the third pairs of contact springs of the three finders in series to wire junction 302;

thence by way of the fourth pairs of contact springs of the three finders in series to wire junction 303; thence by way of the fifth pairs of contact springs of the three finders in series to wire junction 304; and

I thence by wayof the sixth pairs of contact springs of the three finders in seriesand the dotted conductor 310 to wire junctlon 305, where it joins starting wire 230 again and line relay 100.

provided in the release magnet 1053 wh c.

forms a complete loop. Conductor J. 1 shown dotted to ind' '1 through other pairs shown before returning to wire j unctic i The individual starting wires 1 :1y be considered'as taps taken on" from t e V main loop circuit at the first finder switch bank. Ii: will be observed that the above described loop circuit is divided into as r any sections as there are finder switches by means of the insulating pieces 290, 291, and 292 which correspond to insulating piece 47 (Figs. 1

and 4:). The finder-switches may be consid ered as each standing, when idle at the division point between two adjacent sections, each finder being adapted to serve those lines whose starting wires are tapped onto the section immediately in front of that finder.- "There may be but one starting wire attached to a given section or there may be many more depending obviously on the position of the other finders.

For the sake of additional clearness I have shown in Figure 6, the loop circuit and six starting wires of F 5,"-togcther with a starting relay in'cach of the three finders, all unnecessary details being omitted. When taken in connection with'the foregoing description of F ig, 5', it is thought that Fig. 6 will be understood without difiiculty.

The relays shown at H (Fig.6) are common to a group of finder switches and may be-termed emergency starting and stopping relays. Their functions will be more fully explained hereinafter.

Returning now. to Figure 1, the finder switch C is connected directly with the selector switch D which may be of the general type of selector switch disclosed in U. S. Letters Patent No. 815,321 granted March 13, 1906, to Keith Erickson and Erickson; beinng, howeven of the particular type disclosed in British patent to the Automatic Telephone Manufacturing Company. No. 2543 of 1914. Among other details the selector 1) comprises a bank of contacts arranged in horizontal rows or levels which contacts are adapted to be engaged by a set of wipers 120, 121. and 1 2, carried upon a shaft (not shown) which has a vertical movement controlled by vertical magnet 109, and a rotary movement C(illtl' )ll \(i by a rotary magnet 110. The operation of the various parts of the switch is controlled through the medium of the double wound lVleans to? perm switch to be restored to normal position is upon energizing. withdraws the retain 1m pawls fromthe shaft. The contacts 112 and 113 make against their respective springs only when the shaft been raised one or more steps from its normal position. The relays IOeL-and 106 are slow a ting. i. 0.. each of these relays isable to retai. its armature ing the for an instant after its energizing circuit is welt shown herein ber of? groups or on connectors in turn knowin a selector o if the type y be lven acce s to a numuector switches, which we access to groups of subscribers lines for the purpose of comvpletln'g connections 1 thereto.

Un'eoi these connectors is shown at 12, F1 22. The connector E may be of the general type ot connector switch disclosed in S. LettersPatout No. 815,176 granted March 13, 1906, to

Keith, Erickson and Erickson; being, how ever, of the particular type disclosed in British patent to the Automatic Telephone Manufacturing Company, No. 2270 of 1914. Among other details the connector E comprisesa bank of contactsarranged in horizontal rows or levels, which. contacts are adapted to be ei'igaged by aset of wipers 160, 161, and 162, carried upon a shaft (not shown) which has a vertical movement controlled by the vertical magnet 148;. and a swering bridge relay 150. The ringing relay 149 afi'ords means for proyecting ringing current over the called line to signal the called subscriber. -Means for restoring the switch to normal position is provided in the release magnet 152 which, upon energiaing, withdraws the retaining pawls ilroni the shaft and restores the side switch wipers to their first position. The COllttlCbS 15 1 and 155 make contact with their respective springs only. when the shaft has been raised one or more steps from its normal position. The relays 153 and 146 are slow acting.

The connector it has access through its wipers and bank contacts o a group ofsubscribe rs stations one oi which is shown at A. The substation A may be siu'iilar in all respects to substation i and is provided with similar ,indiriduzd line ciiu-iipment.

For supplying current tor operating and talking purposes l have shown a battery B having one terminal fll'fllilitlctl. The battery B shown in Fig. 5 Ma he the seine bat uy or a difli'erent battery .'o1n that illustrated atB in Fig. 2. For supplying ringing current I have shown a generator It and for busy signaling purposes I have shown a busy signaling machine Q.

llavlng given a general description of the apparatus 1 will now proceed to describe the operation ot a system embodying the in the art, havingv been fully described in'the publications referred to; its operation. will be descrihedin a more or lessgeneral man'- ner, the details being given onlywhen they have to do in some way with the application of the principles of my invention.

Referring now to Fig. 1', the subscriber at substation A, upon removing his receiver to initiate the call, coinpletesa circuit which includes a winding oi' line relay fQL-rindi- 'vidual starting wire secure a pair of startingrelays in that finder switch whose wipers require the least movement in order to reach the contacts in its bank allotted to the line of substation A. Assuming that'the wipers of finder-switch C- are already resting upon contacts individual to substation A, the above mentioned circuit may he. tracedas follows: ground at G winding=55 of relay 5 1-, winding ot relay 53, contact 70, arma ture 69, contact 68, spring 67, Wiper41, bank contact 3o starting wire 321, contact- 29, spring 30, contactQ'T, armature 26, line conductor 11, to and through substationA line conductor 12, armature 24, contra/ch25, and wind' of line relay 21 to battery B. In response to current flow in thefabove path, relays 21, 53, and 54% attract their armatures. The armature of relay 21 is adjusted with a ratl'ier long stroke and the Contact against springSQ is made before spring 30 is sepa rated troui. contact 29; as a result of the latter operation, which takes'place near the end oi the stroke, the original energizing circuit is broken, but not before relays 53 41 54. have fully attracted their annatures. ayQl is enabled to complete its stroke by reason of the new path to ground by wayof common relay 90 closcdby armature 28 and spring 30. A temporary locking circuit for relay 5% may now be traced as follows: ground at G winding rjfi'lof relay '54, con- I tact 66 spring (33,W1PQF ii2, bank contact 37,

spring 32, armature 31., holding winding 23 ot line relay 21, mnlwinrlirrg of cut oli' relay 20 to battery It. The cut off relay 20, upon energizing,breaks the energizing circuit oi" winding 22 oct lino relay .51. but relay 21 retains its armature attracted by reasonol its holding windiijig 23 now carrying current in series with the cut off relay winding.

An instant utter. the temporary locking circuit o't relay fi twas established by the energization of relay. 21, (the slow acting pleting; an energizing circuit for line switching relay 51 as follows :ground at G arma ture 7 8, contact 80.?armatur9 74,.contact 75,

relay 53 retracts its armature, thereby com 1 holding winding 56 of relay 54, armature 81, contact 82, and winding of relay 51 to battery B. Relay 51, upon attracting its armature, brin -s about the following circuit changes. by bringing armature 64 into engagement with spring 63 and by separating the latter from contact 66, the temporary locking circuit of relay 54 by way of its winding 55 is broken and relay 54 remains energized by reason of its low resistance holding winding 56. By the substitution of winding 56 for winding 55, the test contact 37 and its multiples are brought sufliciently near to ground potential to make the line of substation A busy to other finder switches that may be started. Also, by reason of the low resistance of holding winding 23 of line relay 21, the conductor 15 and the multiple .test contacts in the banks of connector switches to which 'it extends are brought suflicient-ly near to ground potential to make the line of substation A busy to those connector switches. As a further result of the energization of relay 51 the wiper41is disconnected from relay 53 and is connected directly to wiper 40 in an obvious manner. This is done for the purpose of maintaining the continuity of the loop starting circuit while finder switch C is busy. Finally, by bringing armatures 59 and 60 into engagement, respectively, with contacts 61 and 62, relay 51 extends the line conductors 11 and 12 .to the double wound line relay 100 of the selector D. Two energizing circuits for relay 100 may now be traced, one of which extends over the following path: ground at G winding 103 01 relay 100, contact springs 115'and 116, contact 61, armature 59, wiper 43, bank contact 38, conductor 16, line conductor 12, substation A, line conductor 11, conductor 17, bank contact 39, wiper 44, armature 60, contact 62, contact springs 117 and 118, and winding 102 of relay 100 to battery B. The second energizing circuit extends as follows: ground at (:r", armature 78, contact 80, ar mature 74, contact 75, armature 60, contact ('32, contact springs 117 and 118, and winding 102 of relay 100 to battery B. Ordinarily the latter circuit, which is in effect a short circuit of winding 103 and the substation A, could be dispensed with. Its purpose will appear later.

* Upon attracting its armature, the line relay 100 completes an energizing circuit for the slow acting relay 104, which relay, upon energizing, prepares circuits for the vertical and

rotary magnets

109 and 110 in the well known manner and also completes a holding circuit which may be traced over the following path: ground at G and contact springs 131) and 131 to armature 64, where the circuit divides, one branch extending by way of the winding of line switching relay 51 to battery I and theother branch extending by .way

of spring 63, wiper 42, bank contact 37, spring 32, armature 31, winding 23 of relay 21, and win ding of cut oil? relay 20 to battery B. It will be observed that as soon as the above holding circuit is established the winding 56 of relay 54 is Short circuited. Upon deenergizing, relay 54 breaks the last described energizing circuit of line relay 100,. thereby leaving the selector D under the control of the substation A.

The purpose of the auxiliary energizing circuit for line relay 100may now be seen. Should the subscriber at substation A remove his receiver and replace it, in the interval between the pulling up of relay 21 and the pulling up of relay 104 of theselector, relay 54 would remain locked up by its winding 56, thereby maintaining the finder switch in a busy condition until the next call by substation A. The auxiliary energizing circuit for line relay 100 is provided to obviate this possibility.

Before continuing with the operation of the selector 1) and connector E it will be well to consider the operation in the case where no finder switch is resting upon the contacts of the calling line. We will assume that the finder switch C is idle and that its wipers happen to be nearer to the cont-acts of the line of substation'A than the wipers of any other finder. It follows then that the section of the starting loop to which starting wire 321 is tapped will terminate in the bank contact upon which wiper 41 is resting, as explained in connection with Fig. 5.

Upon the removal of the receiver at sul station A an energizing circuit is completed as previously described for

relays

21, 53, and 54, except that in this case the circuit includes a portion of the starting loop. Relay 21, upon energizing, prepares a circuit for thecut-off relay 20 by bringing armature 31 into engagement with spring 32, breaks the original startii'lg circuit by separating contact 29 and spring 30, and locks itsei'i by bringing armature 28 into engagement with spring 30, 'all as previously described. The instant spring 30 is separated from contact 29, relay 54 deenergizes but relay 53, being slow acting, retains its armature for an instant thereby completing the following circuit: ground at G armature 78, contact 79, armature 76, contact 77, winding of relay winding of rotary magnet 50, interrupter contact springs 58, and common relay 91 to battery B. Relay 52, upon attracting its armature 72 completes'the above circuit over a path which is independent of the relay 53, whereby the deenergization of this relay an instant later is without effect.

As soon the circuit just described is pleted the rotary magnet 50 operates to vibrate its armature 211 by means of the interrupter contact springs 58, thereby ro tating the wipers 40-44, inclusive, in search of the contacts of the calling line. Relay 52, being slow acting, retains its armature although its circuit is broken at each energization of magnet 50. During the rotation of the finder switch, wiper 41 is disconnected from relay by the attraction of armature 69 of relay 52 and is con.- nected at the same time to wiper 40 for the purpose of maintaining the continuity of the starting loop.

VVhen wiper 42 arrives at bank contact 57 an energizing circuit is completed, for relay 54 and cut-off relay over the following path: ground at G, winding oi.

relay 54, contact 06, spring 63, wiper 42,

elusive.

bank contact 37, spring 32, armature 31, winding 23 of relay 21, and winding of cutoff relay 20 to battery 13. The above circuit is the same as one previously described and referred to as the temporary locking circuit of relay 54. Upon attracting its armature, relay 54 breaks the rotary magnet circuit by separating armature 7 8 and contact 79, thereby stopping the rotation and bringing the wipers 4044, inclusive, to rest upon contacts 35-39, in-

From this point the operation is the same as described in the case where it was assumed that the wipers of finder switch C were already resting upon the contacts 01 the line of substation A.

We may now return to the selector D and consider briefly its operation. In response to the manipulation of the dial at substation A in accordance with the first digit of the desired number, the impulse wheel 7 interrupts the circuit of the line relay 100 a number of times in the well known manner. ,As a result of these interruptions the line relay 100 is deenergized a corresponding number of times, sending an impulse at each" deenergization from ground at (.1 to the slow acting relay 106 and the vertical magnet 100 in series. The vertical magnet, in] response to these impulses, steps up the shaft until the wipers stand opposite the horizontal level in which are located contacts which are terminals of the desired group of connectors. The relay 106, being slow acting, retains its armature during the series of impulses and closes a circuit for the test relay 108 whichlatter relay prepares a circuit for the rotary magnet and locks itself to ground at G. At the end of the series of impulses the relay 106 deenergizes, thereby closing a circuit for the rotary magnet 110, whereupon the wipers 120, 121, and 122-start rotating in search of a trunk extending to an idle As iswell known, the rotary connector. magnet interrupts its own circuit and also the locking circuit of the test relay at every euergization, the contacts in the latter circuit, liowever, being short circuited by the test wiper 121 while passing over busy or grounded contacts. As soon, therefore, as

the test wiper reaches an ungrounded test contact the test relay falls back and opens the rotary magnet circuit, thereby bringing the wipers to rest upon contacts which are terminals of a trunk leading to an idle connector switch, assumed in this case to be the connector E. As a further result of the deenergization of the test relay 108, a circuit is completed for the line switching relay .107, which relay, upon energizing, disconnects the extended line conductors 12 and 11 from the windings of the line relay 100 and further extends them by wayof wipers 120 and 122 and bank contacts 123 and 125, to" the double wound linerelay 140 ofthe connector E.

The line relay 140 thereupon energize's over thepreviously traced circuit through substation A, and completes an energizing circuit for slow acting relay 153. Relay 153, upon energizing, prepares a circuit for the vertical androtary magnets143 and 144 and also completes a new holding circuit as iollowsz ground at G contact springs 170 and 171, bank contact 124, and wiper 121 to wire junction 132','where the circuit divides, one branch extending by way of contact springs 133 and 134 and winding of line switching relay'107 to battery B, while the other branch extends by way of contact 112 and contact 111 to wire junction 135, where it joins the previously described. holding circuit extending back: to the finder switch C. y

The subscriber at substation A may now operate his dial in accordance with the second digitof thedesired number, resulting in this case in deenergizations of the line ,7

relay 140 of the connector E. At each deeuergization the line/relay 140 sends an impulse from ground. at G to the slow acting relay 146 and the vertical magi-let 143 in series, side switch wiper 156 being in its first position. The vertical magnet, in response to these impulses, steps up the shaft until the wipers stand opposite the horizontal level in which are located contacts which are terminals of the line of substation A. The relay 146 being slow acting, retains its arma ture during a series of impulses and main tains a circuit from ground at G to the private magnet 147. At the end of the series of impulses the relay 146 and the private magnet deenergize, the latter controlling the side switch wipers in the usual manner, to advance them to their second position. 0

The subscriber at substation A may now operate his dial in accordance with the third 1 a and final digit of the desired number, resulting: as bqiiore in deenergizations of the line rt 140. In this case, however. the line relay sends impulses to the slow acting relay 1 16 and the rotary magnet 144i, side switch wiper 156 being in its second position. The rotary magnet operates in response to these impulses to rotate the wipers 100, 161, and 162 until they rest, respectively, upon

contacts

163, 16 i, and 165, these contacts being terminals 01"- the line of substation A.

As side switch wiper 15 comes into engagement with its third position contact point, a circuit is completed troniground at G by way of wiper 161, bank contact 16%, ans winding of cutoff relay 20 to battery B. The cut-off relay 20, upon energizing, disconnects the line conductors of substation A from their connections atthe line relay 21. Ground at G also extends to multiples of contact 164 in the banks of other conn ctors of the group, thereby making the line of substation A busy to other calls.

By the engagement of side switch wipers 158 and 159 with their third position contact points the line conductors 11 and 12 are extended to the wipers 160 and 162, respectively, thereby completing the connection be tween the two substations. By the engagement of side switch wiper 156 with its third position contact point, a circuit is completed for the ringing relay 149 in series with the interrupter I, whereby ringing current is projected intermittently out over the line of substation A to signal the called subscriber.

Thesubseriber at substation A has now established the required connection with sub I station A and the bell at the latter substation is being rung to attract the attention of the subscriber. l/Vhen the subscriber at substation A removes his receiver from the hook a circuit is completed for the double wound answering bridge relay 150, which relay serves to supply talking battery to the transmitter at substation A. clay 150, upon energizing, completes a circuit for the ring cut off relay 148, which relay locks up and breaks the circuit of the rjn 'ing'relay 14-9, thereby st() )pi11g the riugi its 'a further result oi. the energizaticn of relay 150, the incoming line conductors are rm "versed as regards their connection with the windings of line relay 140. This operation is without importance in the system shown herein, although it is provided in case it is desired to operate meters or similarappa ratus. I

The calling and the called subscriber may now converse without further effort, the voice currents taking the path shown by the heavy lines.

Upon the completion of the conversation the subscribers will hang up their receivers. By the replacement of the receiver at sub- :ion A the circuit of line relay 140 is broken. llpon deenergizaing relay 14.0 breaks the circuit of slow acting relay 1:33. Upon the deenergization of relay 153, the connecand relay so it V" s 1 Jul, anc li e I v ier switch U.

switching relay line relay and c energized, whereupon all the have been restored to normal relay 51 is made slight sure that spring ii not make against contact 66 until ariii re oi the leaves spring 352. 'llhe reason tor ent obvious. g atien of a connector such as the coniiiector lil when the called line is busy is well known and has been :iully described in the publications referred to. My invention involves nothing new i connection with this 'fea'ture, consequently it is thought to be un necessary to describe such operation here,

l'ieterring now to l" 5, I will describe the operation or": the relays shown at H which relays may be termed emergency starting and stoppin 4 relays. As implied above these relays perform no useful function in the ordinar operation of the system but are PlOVldE-(l to care for extraordinary contions. The relays and 91 are of rather wresistance nd are in series, respectivel with a common locking wire extending to all the line relays of the group of lines, and coi'nmon battery supply wire extending to erotary magnets of all theiinder switches or the group The relays 92 and 93 normally energized and are controlled, respectively by the relays 91 and 90.

' From the previous description of the operation of finder switch C, it will that the line relay of a calling line up by way of common leclni during the time a under svxitiili is rotating 0 {ind that line. time the retary magi oi all the switches cl the group ie in series 0.1: i i ll, i, l lows that in the ordinary system whenever relay 9L)v is 91 will be energised also.

-Assume now that two subscribers whose startinewircs hapoen to be tapped on to the s' as section of the st ,ng loop remove their receivers at the no instant. It is evident that but one finder switch will be st: ted. This finder will stop at whichever line it reaches first, whereuprni relay 91 will deenergize, but relay 90 will remain enerer still Relay 91 beed since the second calling subsci has his line relay lociup 131'" slow z 'iough in eer e and retains its switch cranes to r i line.

calling line. The ungrounded pole of battery B is now connected to conductor byway of back contact of relay 93 and back We will assume now that a subscriber removes his receiver and thereby starts a tinder switch hunting for his line; but before the finder switch reaches his line, the receiver is replaced. By the replacement of the receiver the line relay of the calling line is deenergized and battery potential from the cut-oit relay is removed from the multiple test contacts of that line in the finder switch banks. finder which *as started arrives at the contacts of the line in question, its test wiper finds no battery potential and the finder switch is unable to stop, but will continue to rotate indefinitely. I provide, however, aconductor indicated by reference character 96 which at this time will have battery potential upon it by way of back contacts of relays 90 and 92; Conductor 96 is joined to one or more multiple test contacts in the finder banks and affords means for stopping a rotating finder switch when there is no calling line waiting to be served.

It will be seen from the foregoing that I have provided a very efiicient method of startin finder switches in a system of the genera-[type described, by which the movement of the finders is reduced to a mini mum; and it will be seen further that I have provided certain new and advantageous circuit arrangements for accomplishing the foregoing and other beneficial results, thereby tending to increase the general serviceability of a finder switch system.

While I have described in the foregoing certain specific embodiments of my im'ention, I do not wish to be held strictly to the forms shown herein, for various adaptations will no doubt suggest themselves to persons skilled in the art. 'I desire, tl'iere'tore, to include and have protected by Letters Pat out all forms and modifications of my in-' vention which may come within the scope of the appended claims.

VVhat- I claim as my invention 1s:

1 In atelephone system, a group of lines,

link circuits each comprising a pair of talking conductors, a finder switch for each link for connecting a calling line of said group thereto, and a pair of normally closed contact members in each of said finder switches individual to each. of said lines.

2. In a telephone system, a group of lines,

trunk lines. finder switches and selector in pairs for extending .p to an idle one of and a pair oi normally line oi said trunk lines,

\Vhen therefore. theclosed contact members in each of said finder switches individual to each of said first mentioned lines.

3. In telephone system, a group of lines,

link circuits, a finder switch for each link for connecting a calling line of said group thereto, a pair of normally closed contact members in each of said .finder switches individual to each "of said lines, and a circuit including all of said contact members in series.

4. In a telephone system, a group of lines, trunk lines, finder switches and. selector switches connected in pairs .for extending a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first mentioned lines, and a circuit including all of said contact members in series.

5. In a telephone system, a group of lines, link circuits, a finder switch for each link for connecting a calling line of said group thereto, a pair of normally closed contact members in each of said finder switches individual to each of said lines, a circuit including all of said contact members in series, and an insulating member associated with each of said finder switches for sepapairs.

trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first mentioned lines, a circuit including all of said contact members in series, and an insulating member a sociated with each of said finder switches for separating the contact members of one of said pairs.

7. In a telephone system, a group of lines, link circuits, a finder switch for each link for connecting a calling line of said group there to, a pair of normally closed contact members in each of said tinder switches individual to each of said lines, a circuit including all of said contact members in series, and an insulating member associated with each of said finder switches for separating the contact me'mbers of one of said pairs, whereby the said circuit may be divided into sections. 8. In a telephonesystem a group of lines, trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first mentioned lines, a circuit including all of said contact members in series, and an insulating member associated with each of said finder switches for separating the contact members 6. In a telephone system, a group of lines,

of one of said pairs, whereby the said circuit may be divided into sections.

9. In a telephone system, a group of lines, link circuits, a finder switch for each link for connecting a calling line of said group thereto, a pair of normally closed contac members in each of said finder switches individual to each of stid lines, a circuit including all of said contact members in series, an insulating member associated with each of said finder switches for separating the contact members of one of said pairs, whereby the said circuit may be divided into sec-- tions, a controlling relay in each of said finder switches, and means for connecting Zach of said relays to one of said sections.

10. In a telephone system, a group of lines, trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of said trunk ines, a pair of normally closed Contact members in each of said finder switches individual to each of said first mentioned lines, a circuit including all of said contact members in series, an insulating member associated with each of said finder switches for separating the contact members of one of said pairs, whereby the said circuit may be divided into sections, a controlling relay in each of said finder switches, and means for connecting each of said relays to one of said sections- 11. In a telephone system, a group of lines, link circuits, a finder switch -for each link for connecting a calling line of said group thereto, a pair of normally closed contact members in each of said finder switches individual to each of said lines, a circuit including all of said contact members in series, and a branch of said circuit for each of said lines.

12. In a telephone system, a group of lines, trunk lines, finder switches and selector switches connected in pairs for extend-- ing a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first lines, a ci cuit including all oi said contactmembers in series, and a branch of said circuit for each of said first lines.

13. In a telephone system, a group of tor switches connected in pairs for extending a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first lines, a circuit including all of said contact menu hers in series, a branch of said circuit for each of said first lines, and a relay individual to each of said first lines for disconnecting its associated branch.

15. In a telephone system, a group of lines, link circuits, a finder switch for each link for connecting a calling line of said group thereto, a pair of normally closed contact members in each of said finder switches individual to each of said lines, and a circuit including all of said contact members in series, each of said lines when idle having one of its conductors conductively connected to said circuit.

16. In a telephone system, a group of lines, trunk lines, finder switches and selector switches connected in pairs for eXtending a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first lines, and a circuit including all of said contact members in series, each of said lines when idle having one of its conductors conductively connected to said circuit.

17. In a telephone system, a group of lines, link circuits a finder switch for each link for connecting a calling line of said group thereto, and a starting relay in each of said finder switches, each starting relay being controllable, when its associated finder switch is idle, either from any line in said group, or from only one of said lines, or from any intervening number of lines in said group.

1.8. In a telephone system, a group of lines, I

trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of said trunk lines, and a starting relay in each of said finder switches, each starting relay beingcontrollable, when its associated finder switch is idle, either from any line in said group, or from only one of said lines, or from any intervening number of lines in said group.

1 9. In a telephone system, a group of lines, link circuits, a finder switch for each link for connecting a calling line of said group thereto, and a starting relay in each of said i finder switches, each starting relay being c ntrOIlable, when its associated finder switch is idle, either from any line in said group, or from only one of said lines, or rom any intervening number of lines in said group.

20. In a telephone system, a group of lines. trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of said trunk lines, and a starting relay in each members in each of said finder switches in-' dividual to each of sald lines, an insulating member associated with each of said finder switches for separating the contact members of one of said pairs, means for rotating each of said insulating members during the operation of its associated finder switch, and

means for connecting the two contact meinbers oil? a pair when separated by the insulating member of a busy finder switch.

22. In a telephone system, a group of lines, trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of a said trunk lines, a pair of normally closed contact members in each of said finder switches individual to each of said first lines, an insulating member associated with each of said tinder switches for separating the contact members of one of said pairs, means for rotating each of said insulating members duringthe operation of its associated finder switch, and means for connecting the two contact members of a pair when separated by the insulating member of a busy finder switch.

23. In a telephonesystem, a. group of lines, link circuits, a finder switch for each link for connecting a calling line or said group thereto, a pair of normally closed contact 'members in each of said finder switches in dividual to each of said lines, a circuit including all of said contact members .in series, an insulating member associated with each oi said-tinder switches for, separating the contact members of one of said pairs, whereby the said circuit may be dix 'ided into sections, and means for rotating each of said insulating members during the operation of its associated findcr'switch to vary the length of said sections.

. 24. In atelephone system, a group of lines, trunk lines, finder switches and selector switchesconnected in pairs for extending a calling line of said group to an icle one of said trunk lines, a pair of normally closed contact members in each of said finder switches indiyidualto each oi? said first lines, a circuit including all. of; said contact members in series, an insulating member associated with each oi said finder switches for separating the contact members of one of said pairs, whereby the said. circuit may be die rided into sections, and means for rotating each of said insulating members during the operation-of its associated finder switch to vary the length of said sections 25. In a telephone system, a group of lines, link circuits, a finder switch for each link for connecting acalling line of said group thereto, a pair of normally closed contact membersin each oi said finder switches/in dividual .to each of said lines, a circuit including all of said contact members in series, an insulating member associated with each of said finder switches for separating the contact members of one of said pairs whereby the said circuit may be divided into sections, and means for connecting the two contact members of apair whenseparated by the insulatinn member of a busy finder switch, whereby the number of said sections is made equal to the number of idle finder switches. i

. 26.In a telephone system, agroup of lines, trunk lines, finder switches and selector switches connected in pairs for extending a calling line of said group to an idle one of said trunk lines, a pair of normally closed contact members in each of said. finder switches individual to each of said first lines, a circuit including all of saidcontact members in series, an insulating member assoc-i ated with each of said finder switches for separating the contact members 01 one oi? said palrs, whereby the said circuit may be divided into sections, and means for connecting the two contact members of a pair when separated by the insulating member of a busy finder switch, whereby the number oi said sections is made equal to the number of idle finder switches.

27. In. a telephone system, a group of lines, a telephone for each line, a lesser group of automatic switches, a controlling circuit for said switches including a pair of normally closed contact members individual to each of said lines, and means associated with. said switches for establishing a talking circuit between any two of said lines.

28. In a telephone system, a group ol'- lines, a lesser groin) ol" automatic switches, a controlling circuit incl uding a pair of nor mally closed contact members individual to each of said lines in each of said switches.

and means associated with said controlling circuit for starting said switches one at a time.

29. In a telephone system, a group of lines, a lesser group of automatic switches for extending said lines when calling, a controlling circuit including a pair of normally closed contact members individual to each of said lines in each of said switches, and means associated with said controlling circuit responsiveto successive calls for starting said switches in succession.

30. In a telephone system, a group of lines, a lesser group of automatic switches. a controlling circuit including a pair of norlift) mally closed contact members individual to each of said lines in each of said switches, means associated with each of said switches for eparating the contact members of one of said pairs, whereby the said controlling circuit may be divided into sections.

31. In a telephone system, a group of lines a lesser group of automatic switches, a controlling circuit including a pair oi? normally closed contact members individual to each of said lines in each oi said switches,

and means associated with each of saic switches for separating the contact members of one of said pairs, whereby the said controlling circuit my be divided into sections equal in number to the number 0'! said switches.

32. In a telephone system, group of lines, a lesser group of automatic switches, a controlling circuit including a pair of normally closed contact members individual to each of said lines in each of saic switches, means associated with each of said switches for separating the contact members one of said pairs, whereby the said controlling circuit may be divided into sections equal in number to the number of said switches, and means included in each of said switches for connecting the members separated by first means when the associated switch is busy, whereby the number of sections is made equal to the number of idle switches.

33. In atelephone system, a group of lines, a lesser group of automatic switches, a controlling circuit including a pair of normally closed contact members individual to each of said lines in each of said switches, means associated witheach Oiii said SifltClltlE; for separating the contact members of one of said pairs whereby the said controllin circuit may be divided into sections equal in number to the number of said switches, a controlling relay for each of said switches, and means for connecting each relay to one of said sections.

In a telephone system, a group ct lines, a lesser group of automatic switches-s. for extending said lines vhen calling, and means for starting said switch s in succession responsive to successive calls comprising a controlling circuit including a pair of normally closed contact members individual to each of said lines, and a branchof said controlling circuit for each of said lines.

35. I11 a telephone system, a group of lines, a lesser group of automatic switches, for extending said lines when calling, and means for starting said switches in succcssion responsive to successive calls comprising a controlling circuit including a pair of normally closed contact members individual to each of said lines in each of said switches, and a branch of said controlling circuit tor each of said lines.

36.111 a telephone system,

a group of lines, a lesser group of automatic switches, a controlling circuit including a pair of normally closed contact members indiyidual to each of said lines, a branch or said controlling circuit extending over each ct sai ines, and means for disconnecting each ot said branches from its associated line when the line is busy.

In a telephone system, a group of lines, a lesser group 01? automatic switches, a controlling circuit con irising a continuous loop and including 1 pair or norn'ially closed contact members individual to each of said lines in each 01 said switches, a branch of said controlling circuit ior each of said lines, and means for disconnecting each oi said branches when its associated line is busy.

38. In telephone system, a line, an automatic switch, a finder switch operable for extending said line to said automatic sw'" controlling relay for said tinder a line relay for said line having a main and an auxiliary winding, a circuit including said controlling relay and the main winding of said line relay, and meal s controlled by said line relay tor interrupting said circuit.

39. In a telephone system, a line, an automatic switch, a finder switch operable for extending said ine to said automatic switch, a controlling relay for said line: switch, a line relay for said line having amain and an auxiliary winding, a circuit inclucing said controlling relay and the main winding oi? said line relay, d means controlled by said line relay r i .errupting said circuit and for completing it over a path excluding said controlling relay.

d0. telephone system, a line, automatic switch, a finder s (itch operable for extending said line to said automatic switch, a. controlling relay tor said lii'ider switch, a line relay for said line having a main andau auxiliary winding, a circuit including said controlling relay and the main windii of said line relay, means controlled by said line relay for inter-rug said circuit and i'cr completing it over a new path excludiiu said controlling relay, and a uicond circuit for said line relay by way oi its auxiliary winding.

41. In a telephone system, a line, an automatic switch, finder switch operable for e:-; tending said line to said ant natic switch, a controlling relay for sz id iinder switch, a line relay for said inc having a main and an auxiliary winding, a circuit including said controlling relay and the main winding of said line relay, means controlled by said line relay for interrupting said circuit, a second relay for said line, id a second circuit including said second relay and said auxiliary winding.

in a ijelepl ne s 1a matic switch, a finder switch il (l extending said line to said automatic switch,

a controlling relay for said finder switch, a line relay ior sald line havlng a main and an auxiliary winding, a ClICllllJ' including said controlling relay and the main'winding of:

said line relay, means controlled by said line relay for interrupting said circuit, a cutoil' extending said line to said automatic switch,

a controlling relay for said finder switch, a

'2 line relay for saidline having a main and an auxiliary winding, a circuit including said controlling relay and t 1e main winding of said line relay, means controlled by said line relay for interrupting said circuit and for completing it over path excluding said controlling relay, a cut-off relay for said li and a test circuit including said cut-off relay and said auxiliary winding.

44:. In a telephone system, a line, an automatic switch, a finder switch for extendin j; said line to said automatic switch, a line relay tlior said line'having two windings, a controlling relay for said finder switch, a circuit for initiating the operation of said finder switch including said controlling relay and one winding oi said line relay, and a circuit forstopping the operation of said finder switch including said controlling relay and the other winding of said line relay.

45. In a telephone system, a line, an auto Inatic switch, a finder switch for extending said line to said automatic switch, a line relay :For said line having two windings, a pair of controlling relays for said finder switch, a circuit for initiating the operation of said finder switch including said controlling relays and one winding of said line relay, and a circuit for stopping the-operation of said finder switch including one of said controlling relays and the other 'wi n ding of said line relay.

it). In a telephone system, a line, an automatic switch. a finder switch for extending said line to said automatic switch, a controlling relay in saidfinder switch, a line relay for said line, and a circuit for initiating the operation of said finder switch, said circuit including said line and said relays.

i 47. In a telephone system, a line, an automatic switch, a finder switch for extending said line to said automatic switch, a pair oil controlling relays in said finder switch having different time constants, a line relay for said line, and a circuit for initiating the op oration of said finder switch, said circuit including said line and said relays.

48. In a telephone system. line, an automatic switch, a finder s vitch for extending l line to said automatic switch, a controlling path to the relay in said finder switch, a line re-' lay for said line, a circuit for initiating the operation of said finder switch, said circuit including said line and said relays, and means under the control of said line relay for interrupting said circuit.

49. In a telephone system, a line, an automatic switch, a finder switch for extending said line to said automatic switch, a pair oi controlling relays in said finder switch having different time constants, a. line relay for '7 sald line, a circuit for initiating the operation ofsaid finder switch, said circuit including said relays, and means under the control of said line relay for interrupting said circuit.

50. In a telephone system, a line, an automatic switch, a finder switch for extending .said line to said automatic switch, a controlling relay in said finder switch, a line relay for said line, a circuit for initiating the operation of said finder switch, said circuit including, said line and said relays,and means under the control of said linerelay for interrupting said circuit, and for completing said circuit over a different exclusion of said controlling relay.

In a telephone system, a line, an automatic switch, a finder switch forextending said line to said automatic switch, a pair of controlling relays in said 'finder switch having different time constants, a line relayior said line, a circuit for initiating the operation of said finder switch, said circuit including said line and said relays, and means under the control of said line relay for interrupting said circuitand for completing said circuit over a different path to the exclusion of said controlling relays. i

52. In. a telephone system, a group of lines, a lesser group of automatic switches, finder switches for extending a calling line o'l? said group to an idle one of said automatic switches, a relay common to said lines. a relay 0 common to said finder switches, and a circuit for initiating the operation of one of said finder switches controlled jointly by said relays. I

53. In atelephone system, a group of lines, a lesser group of automatic switches, finder switches for extending a calling line of said group to an'idle one of said automatic switches, a relay common to said lines, a relay common to said finder switches, and a circuit controlled ointly by said relays for bringing an operating one of said finder switches'to rest.

54. In a telephone system, agroup of lines, automatic switches, finder switches less in number than the lines for extending a calling line of said group to an idle one of said automatic switches, and means under the control of said calling line for operating and releasing the selected auto inatic switch without altering the connective posation of its associated finder switch.

55. In a telephone system, a group of lines, automatic switches, a finder switch for each of said automatic switches, fixed terminals for said lines, movable terminals for said finder switches, each of said movable in cup; cent at all times with some one of said fixed terminals, and means whereby a calling line, having its fixed terminal already engaged by a movable terminal, may be extended thereby into connection with one of said automatic switches.

56. In a telephone system, the combination, with a plurality of lines and fixed 11m 'ole terminals therefor, of a plurality of movable terminals each of which is at all times in engagement with one of said fixed terminals, and means under the control of a, calling line for advancing the nearest idle movable terminal into engagement with the fixed terminal of the said ralling line.

57. In combination, a plurality of telephone lines, a lesser plurality oi? automatic tches, fixed mu ple terminals for said lines associated with each of said switches, a movable terminal for each of said switches in engagement with one of its associated multiple terminals, and means whereby a calling line having its multiple terminals unengaged may initiate the operation of that switch whose movable terminal requires the least movement to engage the multiple terminal of the said calling line.

In combination, a plurality of telephone lines, a lesser plurality of automatic switches, a

ur ed multiple terminals for said lines associated with each oi said switches, a movable terminal for each of said switches in engagement with one of its associated nniiltiple terminals, and means whereby a calling line having its multiple terminals unenghged may initiate the operation of that switch whose movable terminal requires the least movement to engage the multiple tcrminals oi the said calling line, said means comprising a or cit-rolling circuit for said last switch including one of the conductors oi. said line.

59. In combination, a plurality of telephone lines, a lesser plurality oi automatic switches, fixed multiple terminals for said lines associated with each oi said switches, a

movable terminal for each of said switches '111 engagement with one oi its assoc ated multiple terminals, and means whereby a calling line having its multiple terminals unengaged may initiate the operation of that switch whose movable terminal requires the least movement to engage the multiple terminals oi the said calling line, said means comprising a controlling circuit for said last stitch having a branch for each of a plural i said line I In a zele hi a group oi: autoin said lines when ca ring, a contro forming a continuous loop and including a o ir of normally closed co: ot members in- *idual to each of said lines in each of said switches, and a branch of said controlling circuit for each of said lines.

(ii. In a telephone system, a group of lines, a group finder switches, a pair of normally closed contact members individual to each of said lines in each of said switches, a circuit connecting all of said contact pairs in series to form a continuous loop and a starting wire for each line connected t said circuit.

(52. In a telephone system, a group of lines a group of finder switches, a pair of normally closed c ntact members indivi ual to each of said lines in each of said switches, a circuit connecting all of said contact pairs in series to form a continuous loop, and starting wires associated with the said lines and switches, respectively, in electrical connection with said circuit.

63. In a telephone system, a group of lines, a group of finder switches for extending said lines when calling, and means for starting said switches in succession responsive to successive calls including a circuit extending a pli'irality of times through all of said switches in series.

G l. In a telephone system, a group of lines, a finder switch for extending said lines when calling, quick and slow relays in said switch, and a starting circuit including said relays connected in series.

In a telephone system, a group oi lines, a group of finder switches for extending said lines when calling, said liinlers having no normal position, and means responsiri to a call "for starting that one of said finders which requires the least movement to locate the calling line.

66. In a telephone system, a group oi lines, a group oi finder switches for extending said lines when calling, said finders having no normal position, and means responsive to a call for starting that one of said finders which requires the least movement to locate the calling line, said. means comprising a starting circuit eXtendng through all of said finder switches in series.

67. In a telephone system, a group of lines, a group of finder switches, fixed contacts for said lines multipled in said switches, movable contacts for said switches for engaging said fixed contacts, the said movable contacts having no normal position as regards the lines, and means responsive to a call for starting that one of said switches which requires the least movement of its movable contacts to locate the calling line.

ling circuit 08. In a telephone'system, a group of telephone lines, a group of trunking switches, a group of finder switchesfor selecting calling lines and extending them to idle trunkinr switches, said finder switches having no normal position as regards the said lines, and the said finders constituting means whereby any calling line which has been so extended and which has a finder associated with it will be again extended by such finder Without selective movement thereof.

69. In a telephone system, a group of telephone lines, trunk lines, a group of finder switches for selecting calling lines and extending them to said trunk 1ines, eachfinder switch being normally associated with the last selected line, and the said finder switches constituting means whereby any calling line already selected will be again extended by the associated finder switch without selective movement thereof. r

70. In a telephone system, a group of lines, an automatic trunking switch, a finder switch for selecting a calling line and extending it to said trunking switch, and means for controlling said trunking switch over the calling line to operate and release the same while maintaining said finder switch in selective position as regards the said calling line.

'71. In a telephone system, subscribers lines, automatic trunking switches controllable over calling lines for extending connections .to called lines, finder switches :t'or selecting calling lines and extending them to idle trunking switches, and means for releasing established comiections, the said v finder switches, after the connections are re leased, remaining in association with the lines, a group of finder switches for extending said lines when calling, fixed contacts for each line in eachfinder switch. and movable contacts for engaging the same in each finder switch, and a circuit "For starting an idle finder switch responsive to a call, the said circuit including a movable contact oi? the finder switch to be started and a fixed contact engaged thereby individual to one of said lines. i,

74:. Ina telephone system; a group of lines, a group offinder switches for extending said lines when calling, means for starting an idle finder responsive to a call, and

.means for starting a second idle'finder responsive to a subsequent call from any line in said group before the finder switch first is started.

started has stopped, said means comprising a plurality of starting w1res,means tor establishing momentary starting circuits over said wires, and means for connect-mg two together whenever any finder starting wires 75. In a telephone system, a group of lines, a group of finder switches for-extending said lines when calling, and means for starting said finders in quick succession responsive to successive calls from any oi the lines in said group, whereby two or more finders may be in pperation simultaneously,

said means comprising a plurality of starting wires. means for establishing momeu tary starting circuits over said wires, and means for connecting two starting wires together whenever any finder is started.

76. In a telephone system, group of lines, a group of finder switches for extend ing said lines when calling, starting relays in said finders each subject to the control of a variable number of said lines, and circuit connections whereby the operation of one finder responsive to a call will vary the number of lines to which the starting relay of another finder is subject to control to an extent proportionate to the movement of the operated finder. I i r 77. In a telephone system, a group of lines, a group of finder'switches for extending said lines when calling, starting relays" in said finders each subjectito the controlo't a variable number of said lines, and circuit connections such that the operation and restoration to idle condition of one finder responsive to a call may increase and dc I crease, respectively, the number of lines to which the starting relay of another finder is subject to control. the au iount of decrease being different from the amount of increase. 78. In a telephone, exchange system, a

plurality of calling substation lines 'arswitches serving said lines, there being one u of said finder switches normally assigned to each of said groups, a starter wire circuit to control the starting of the switch of a succeeding group when the switch normally assigned to the group in which the call originates is busy, contacts for extending said starter w re to a succeeding switch when a calling lin seized, and other contacts for bridging said first named contacts to start a succeeding switch without awaiting the closme of said first named contacts in case a second call is originated in the same group before the first calling line is seized.

80. In a telephone system, a group of lines, a group of finder switches, means dividing-said lines into sub-groups, there being a finder normally assigned to each sub-group, means including a starter wire whereby a calling line in one of said subgroups can start the finder assigned to such sub-group, and means effective when such finder is started for extending the said starter wire to the finder assigned to the next sub-group, whereby another calling line in the same sub-group with the first calling llne can start another finder before the finder first started has stopped.

81. In a telephone system, a plurality of subscribers lines, a lesser plurality ol single motion finder switches, means whereby any calling line can start one of said finders, grouping means whereby separate pluralit-ie's of lines are normally adapted to start different finders, and means whereby a plurality of calling lines which are normally assigned to the same finder can start a plurality of finders and cause said finders to operate simultaneously.

82. In a telephone system, a plurality of finder switches, a plurality of lines normally divided into groups for the purpose of starting said finders, there being a finder assigned to each group of lines, means whereby a calling line in one of said groups can start the finder assigned to such group, and means responsive to the starting of such finder for combining the associated group with the next succeeding group, whereby another calling line in the same group can start another finder while the first started finder is searching for the first calling line.

83. In a telephone system, a plurality of subscribers lines divided into groups, a lesser plurality of finder switches, there being a finder switch normally assigned to each of said groups, and means 'for starting a plurality of finders and operating the same simultaneously in search of lines calling in the same group at the same time, said means including a starter wire terminating in each finder, and contacts for connecting two starter wires together as soon as a finder is started.

84. In a telephone system, a line. a trunk line, a finder switch for connecting said line and trunk line, a line relay energized over said line for starting said finder, a cut-off relay for disconnecting said line relay, a holding winding on said line relay,

and a circuit for said cut-oil relay con:-

and

pleted by said finder when the line trunk are connected, said circuit the holding winding of said line rt 85. In a telephone system, a line, a line, a finder switch for connectin i and trunk line, a test wiper for d i. a test contact individual to said line, a relay energized over said line to s ifinder, said line relay also e'fi'ective to ch the the potential on said testcontact to enalil finder to find the line, a cut-oil relay for disconnecting said line relay, a holding winding for said line relay, ard a cuit established after the line is "found eluding said cut-oil relay, said holding winding, and the said test contact and wiper.

86. In a telephone system, a subscr Hx-l, line, line and cut-ofi' relays individual to said line, an automatic switch for extending said line when calling, circuits for energizing said line relay over the line to start said switch when the call is init'ated. :lor energizing the cut-oil relay after the switch has operated, and for maintaining the line relay energized independent of the line, a second switch for complet n connections to said line as :1 called line, and a circuit completed when the line is ca led i'i'or energizing said cut-ofi' relay while said line relay remains deenergized.

87. In a telephone system, a subscribers line, line and cut-ofi' relays indhridual to said line, automatic switches for extending calls to or from said line, a circuit for ener gizing the cut-oil relay alone when an incoming call is extended to said line, a circuit for energizing the line relay alone when an outgoing call is initiated, means for breaking said circuit before the connection is con'ipletcd, and a circuit for energizing the cut-ofi relay and for maintaining the line rclay energized thereafter until the connection is released.

88. In a telephone system, a subscribers line, a selector switch, a finder switch for connecting said line with said selector, a trunk line connecting the finder and selector and including a release trunk conductor. means for grounding said Conductor it the selector. a wiper switching relay in said finder, line and cut-off relays individual to said line, and circuit connections by which all of said relays are maintained energized over said release trunk conductor.

89. In a telephone system, a group of lines, a finder switch for extending said lines when calling, a starting relay and a motor magnet in said switch, means responsive to a call for energizing and deenergizing said relay, a second relay in circuit. with said first relay and having a slow to release characteristic, and a circuit for said motor magnet completed while the first relay is deenergized and the second relay is energized.

90. In a lIGlQPhOIQliE system, a group of lines, a finder switch :tor extending said lines when calling a st: r y and a motor magnet in said switch, means responsive to a call for energizing and deenergizing said relay, and a circuit for said motor magnet CORIIPlGtBQl when said relay is deenorgized. v

91. In a telephone systen'i a finder switch for extending a suhscrihers line whencalling, a combination starting and stopping relay in' said switch, means for energizing and deenergizing said relay to start said tinder searching for said line and n'ieans for again energizing said relay to stop said finder when the line is found. v

92. In a telephone system a group of lines a finder switch for extending said lines when calling, wipers in said tinder always in engagement with some one of said lines, a starting relay in said finder and a circuit for energizing it n'iomentrrily responsive to a call, and a locking circuit for maintaining the starting relay energized in case the line engaged by the finder wipers is the line which is calling.

93. In a telephone system, a group of lines, a finder switch tor extending said lines when callin wipers in said finder always with said ma in engagement with some one of said lines, a starting relay in said finder, cnrcuitior energizing said. relay responsive to a can.

gized. in case the finder wipers are already in engagement with 'xhe calling line, and a wiper switching relay operated responsire to the continued energization ofsaidstart ing relay. i

9a. In a telephone systen'i, afinder switch for extending subscribers line when'calling, a motor magnet in said finder, means for transmitting a starting impulse to said magnet, and a slow actingrelay in series met for maintaining its circuit closed unlil the lineis found.

95. In a telephone system, a finder switch for extending a subscrihers line when calling, a motor magnet in saidfinder, m is for transmitting a starting nnpulse to said magnet, a slow acting relay in circuit with said motor magnet :tor holding its circuit closed while the finder is searching for the line, and a second relay for opening said circuit to stop the switch when the line is found.

day of February, 1916.

- RODNEY G. RICHARDSUN.

Signed by me at Chicago, Ill. this 10th