US1151544A - Non-interfering extension party-line telephone system. - Google Patents

Description

L S- A? COPY T. s. MARTlN. NON-INTERFERING EXTENSION PARTY LINE TELEPHONE SYSTEM.

APPLICATION FILED NOV. 25, 1905. 1,151,544, Patented Aug. 24, 1915.

5 SHEETS SHEET l.

T. e. MARTIN. v NON-INTERFERING EXTENSION PARTY LINE TELEPHONE SYSTEM.

' APPLlCATlON FILED NOV. 25, I905.

Patented Aug. 24, 1915.

5 SHEETSSHEET 2.

T G. MARTIN.

NON-INTERFERlNG EXTENSION PARTY UNE TELEPHONE SYSTEM,

APPLICATION FILED NOV. 25, 1905.

-1 1 5 1 54%. I Patented Aug. 24, 1915.

5 SHEETS-SHEET 3.

NON-INTERFERING EXTENSIUM PARTY LINE TELEPHON T. G. MARTIN,

E SYSTEM. APPLICATIQN FILED NOV. 25, 1905.

- Patented Aug. 24, 1915.

J SHEETS-SHEET 4.

T. G. MARTIN.

NON-INTERFERING EXTENSION PARTY LINE TELEPHONE SYSTEM.

APPLICATION FILED NDV. 25. 1915. v

1,151,544. Patented Aug. 24, 1915.

5 SHEETS-SHEET 5.

magi? @wjggggj UNIT D STATES PATENT OFFICE.

TALBOT e. MARTIN, or GHICAGO, ILLINOISMASSIGNOR, BY MESNE ASSIGNMENTS, r

arty-Line F1 51 TBU ST A ND SAVINGS' BANK, TRUSTEE, OF CHICAGO, ILLINOIS.

non mrnnrnnmenxrnnsrou PARTY-LINE TELEPHONE SYSTEM.

To all wiwm it mag/ cofncm'." I

Be it known-that I, Taneo'r G.-,MART1 N, a

citizen of the United Cook .gcounty', Illinois,

have invented a certainnewand useful Improvement in Non-Interfering Extension'or Telephone Systems, of which the following. is a specification?- I y y invention relates to telephonesystems automatic telephonesy'stemsofthat type in which more or-less ofithe trunking or. other" switching'operations are produced by the calling-subscriber withoutpthe aid of an0perator, and by; transmitting one or I more electrical impulses to the exchange'or central station, as for example, by momenarily grounding either one or both sidesf the line a t.'the f-subi-station of the callngsubscribeny In;extension-andparty-line telephone sys-c tems'of the particularclass to which my fee invention more especially relates, it is evident that if one'fsubscrlber. is using a hne WhlCl'l 15130111111011 toseveral subscribers, and

ifanother-subscriber on the same line attempts to use histelephone, the connections already' established-- through the medium of 7 said linerwil-l'be broken-that is tosay, the

intruding 1 subscriber. will,

7 in attempting to use: his. telephone,

In such case, the intrusion of aYthirdsuba grounding of bothsides of the established line-circuitaand 'thus set up the conditions which are relied upon as a means for rej machinery by which.- the circuit was established. I'n-other words,-

storing the switching in extension and party-line telephone sys tems it is always undesirable to have the circuits and apparatus so constructed that a third subscriber can listen-in on anestablished circuit and thereby overhear the con-- Vversation between the two subscribers already in possession ofthe line; and inautomat-1c or semi-automatic telephonesystenis of that character in which electrical im- Specifieation of Letters Patent.

Statesof America, and

in general, butmore particularly-to the so-; called extension and party lia e' telephone systems, and especially toautomatic or semiject-to" the supervision of being disturbed or molested by any other operate certain release-circuits 'and thereby release andrestore the 35' switching devices by whichthe talking cir--v uit was-established. Suppose, for example, that one subscriber-0n a line isin conversation witlia subscriber-on another 'line, or with another subscriber on the. same line for party line telephones,

scribe-r on the same line can use the latter Patented Aug. 24, 1915.

' Application-filedfiovember 25, 1905. Serial No. 289,048. I

pulses are used for calling the number of the called subscriber, and for releasmg the switching machinery after ,the subscribers are through talking, itfis important and practically necessaryI find that some provision-be made whereby when any .two subscribers are using a line a third subscriber cannot then manipulate his'tele phone sw tchlng devices in such manner as to break or interfere with the circuit established between the said talking subscribers. It is obvious that this is true of either the so-called extension telephone arrangements in which several extension telephones are connected with a main or master telephone, or of the ordinary party-linev arrangement in which several subscribers are simply bridged across a' telephone line and not suban operator, at-a main or master telephone.

' Generally stated, therefore, theobject of "my invention is the provision of an im proved and highly eflicient extension or party-line telephone system so "constructed that the different subscribers occupying a line in common cannot interfere'wltheach other in the use of such lin e -that is, so con.-

structed that when one subscriber has the use it without any possibility of line .he may subscriber.-

p Special objects of my invention are the provision of an improved lock-out device whereby if one subscriber-is using the line no other sub-- for either switching or signaling purposes; the provision of an improved construct on and arrangement whereby several subscribers may be connected with a, single line in an automatic or semi-automatic telephone systom, and whereby if one subscriber is using the line no other subscriber on the same line can transmit any electrical impulses, e ther for switching or-signahng purposes, or do anything which will endanger the continuity of the talking circuit established bythe subscriber already in possession of the line; the provision of animproved construction and arrangementwhereby the different sub-stations on a' party-line in an automatic telephone system may each be provided with a 'locksoutor cut-oflf. relay. of such character that no subscriber on the line can transmit any'electrical impulses, elther for switching 20 some other subscriber on the same line and the provision of certain details and features phone system Y first-selectors,

or'signalingpurposes, while the talking circult is temporarily in use by some other subscriber on the same line; the provision of a.

non-interfering partyline or extensionteleincluding first-selectors which are each provided witha special set of so-called ofi-normal-springs which are controlled by the selector-shaft, and by means of which the so-called rotary-lineconductor is maintained normally disconnected from the non-grounded terminal of the battery, or other centralized source of current, until after the shaft of the selec tor is raised from its normal position; the

provision of an improved construction and arrangement, involving speclal relays 1n the may call his own line, so to speak, so as to obtain connection with the sub-station of of improvement tending to increase the general efliciency and serviceability of party-- line and extension telephone arrangements of this particular character.

To the foregoing and other useful ends my invention consists in matters hereinafter set forth and claimed;

In the accompanying drawings, Figure; 1 is a diagram showing two party-lines connected together. One of said lines is provided with two sub-stations (#110 and #210) that are bridges in multiple across the line-conductors, and the other is pro- 'vided also with similar stations (#120 and 220). One of said lines is shown connected through a firstselector C and a "connector'D with the other of said lines, which latter .has bridged across it a second firstselector E. All of the substations shown are identical, as well as all of the first-selectors. Fig. 2 is a front elevation ofa substation keyboard mechanism, showing the dial-plate removed and the switch-hook raised. Fig. 3 shows-the same mechanism with .the'switclrhook down. Fig. 4 is a diagrammatic perspective view of the firstselector C, showing the approximate rela tive positions of its parts, the switch-frame not being shown. Fig. 5 is a similar view of the connector D. Fig. 6 is a view similar to Fig. 1, in which the subscriber at station #310 has called and connected with the station #110, on the same line, through the first-selector O and the connector D, the station .#210 being bridged across the line between sub-stations #310 and #110. a

All such sub-stations are provided with the usual'details essential to subscribers stations of the class in question. Sub-station #110, for instance, is provided with a receiver 2 and a switch-hook 3, which latter has radiating from its body a number of cainf-a 'ms 4, 5, 6 and 7, 'said hook being pivand improved circuit con- -nect1ons,whereby a party-line subscriber condenser 15, the latter being contact with the latter.

ceiver is removed. The rotation is due to the tension "of a spring that 1s not shown and the hook is pushed up for the purpose of changing certain circuit connections to be disclosed. Furthermore, said sub-station has a transmitter. 9, alocal battery 10, a ringer 11, an induction-coil 12 wilh a primary winding 13 and a secondary winding 14,: a condenser 15, a lock-out magnet 20, and in addition a signaling device comprising a button 16, a spring 17,. and two contactpoints 18 and 19. When the switch-hook is down, the cam-arm 4 is held in contact with the spring 21, thereby flexingthe said spring in'a downward direction. Said spring is normally in contact,- therefore, with, the arm 4, and in this way completes the ringing circuit which includes the ringer 11 and the normally bridged across the ine in series. Associated with the spring 21 are two sets of springs 22 and 23, and 24', 25 and 26. Members'of each .of these sets, whenleft to their own ignsion, when the switch-hook is up, engage v contact witheach other-that is, the springs 22 and 23 are then in contact, and the springs 24, 25 and 26 are in contact; but whenever the switch-hook depresses the spring 21 the latter permits the springs 22 and 23 to separate and forces, at the same time, the springs 24, 25 and 26 apart,

'throughthe medlum of an insulating washer 27 located between the springs 21 and 26.

. The arm 7 when raised, forces the spring 28 away from the spring 29, whilethe arm 6 permits the spring 30 (which is normally disengaged from the spring 31) to close in' Whenever the switch-hook is drawn down, 'the three the release-springs, are forced into union by the arm 5 on said .sWitch-hook, which arm engages a laterally -projecting piece that constitutes the top extremity of the spring 32 of this group of springs. However, when the switch-hook nears its lowermost position the said arm disengages from said spring and permits the three to again disengage; The calling bytwo push-buttons 35 'and 36, two springs 37 and 38, two contact-points 39 and 40, and the ground post 41. The lock-out magnet, as most clearly shown in Fig. 2, consists of the coil 20 mounted upon a supporting plate 55, which latter is secured to the keyboard frame 42. This magnet is provided with a is energized the spring 48 which normally yoke 43 armature device is represented rests against said insulating pinis pressed away from an adjoining spring 49. Furthermore, said magnet carries on its under 1 front end of saidbrass piece is bent at a right angle upward, and then at a right .angle to the. front, so that whenever the v armature -11 is attracted by the magnet the spring tension in the spring 51 forces the brass member upwardly until the angled section rises in front of the armature 44 and locks it in its attracted position. The switch-hook also carries an angled plate 52 which has a projecting section at the end of.

.which latter a slim rod 53 is hooked. This rod is very light and passes through an opening in the front part of a guide-post 54 which is supported upon the magnet yoke 43. The lower end of said rod works in front of the armature44 and is bent at a right angle horizontally and in a plane parallel with the surface of the armature. lVhen' the switch-hook is depressed the said link is pushed down far enough to drive the lock 50 below the edge of the armature 44, which latter 'then, if the magnet is not energized, resumes its normal position, as

shown in Fig. 3. When said armature is restored the look-out magnet-springs 48 and 49 resume their normal engagement.

As stated, the first-selector is shown in Fig. 4:, and may be .of the general type de scribed in Patent No. 815,321, granted March 13, 1906, to Keith, Erickson & Erickson, This form of selector was well known before the date of my application. It embodies among otherdetails the following well known devices and circuits: the switch shaft 100, which is situated on the front part of the switch, and on the lower section of the said shaft the line- wipers 101 and 102 are fastened, and just above them is a private-wiper, 103. These wipers are all not only insulated from each other, but from the shaft as well. The positions of the wipers are opposite their respective banks-the line-wipers opposite the line bank 104, and the private-wipers opposite the private-bank 105. At its middle portion the shaft carries a cam'106 which, being of a split sleeve design, is tightened to the per section of this hub is smaller than the lower and has formed in it a set .of circular or vertical teeth 110 which are traversed by: a groove or slot 111. This groove 111 is designed to receive the bent and of'the vsocalled shaft support 112which prevents. the i mally,

shaft from rotating unless said end is oppo site one of the grooves between the circular teeth. Still higher up the switch-shaft has fastened to it an arm-like guide 113 which, when the shaft is .in itslowest position," keeps the off-normal springs ll l'and 115 separated from the contact-points 116 and i shaft are vertical and rotary and each movement musttake place at a different time.v By these movements the wipers may be carried into engagement with .any one of the hundred terminals or sets ofcontact-points that constitute the private and linebanks. Since these contacts are arranged in ten vertical and ten horizontal rows, the shaft is made to admit of ten vertical steps and at each level of ten rotary steps.

The movements of the shaft are attained by means of the vertical and rotary linerelays 119 and 120 and through-their respective armatures 121 and 122 which control the springs 123, 124 and 125. Nor-- wipers are onestep lower than the lowest level of their respective banks, and one step to the left of them. Now, when the vertical-line-relay is magnetized, the verticalmagnet 126, which is composed of two coils 127 and 128, is also magnetized. This last magnet has an armature 129 known as the vertical-armature and which has projecting from it a so-called vertical-arm 130 that has pivotally fasteneclto its end a pawl, 131,

known as the vertical-pawl, which is. properly adjusted to engage one of. the circular teeth. 110 atieach vertical movement of the vertical-armature.

'the switch-shaft rests so that the This vertical-pawl isheld in normal position by the retracting- I spring 132 suitably fastened by one end'to the back of the pawl 131 and by the other to the vertical-arm 130. The vertical-armature is provided also with a retracting-I spring 133 between the pawl 131 and said vertical-armature that maintains the latter in its position of rest.- The vertical-arm carries an L-shaped piece 134 on its under side that assists in the unlocking of the switch when it is first brou ht ,into use. This L-shaped piece 134 pro ects under a link 135 known as the release-link, which latter is fastened by oneend to the armature 136 of the release-magnet 137. The release? magnet has assigned to it the' function -of restoring the switch to its normal position after it has been operated. This magnet is composed of two coils, like the vertical-magnet, but only one coilis shown. The release-armature, like the armature of all of the other magnets, is suitably supported, and is kept in normal position away from the release-magnet pole-piece by a retracting-spring'138.

The forward end of the release-link 135 broadens out, and at this broadened section a square opening 139 normally engages with a lug 140 on the double-dog 141. This dou-' ble-dog is pivoted 'on the switch frame by a points 162.

cured by arm 146, it

the pivots 142, and formed on its front part are two dogs 143 and 144 that are designed, the first one to engage with the circular teeth 110, and the last with the longitudinal teeth 109. From the lower side of the double-dog a release-arm 145 projects downward and assists in the restoration of the side-switch when the switch is released.

vThe side-switch comprlses a supporting member 146 known as the side-switch arm. It is pivoted and may be moved about a vertical axis passing through the pivots 147. To the left of the pivots the arm 148 extends rearwardly, and on the end of this arm the side-switch-link 149 is pivotally seone end and at its other engages the lower end of the release-arm 145, the end of the latter being of an inverted T-shape, while the end of the former is bifurcated. Still nearer to theend on the same side, the side-switch-arm 146 carries a pin 150 which binds in'toone piece four wipers 1 51, 152, 153 and 154 known as the side-switchwipers. These wipers are insulated from each other and from the'supporting pin to which. they are all rigidly fastened. The said wipers being rigid with the pin, and the pin being also rigid with the side-switchfollows that when the sideswiteh-arm is rotated about the pivots 147 the side-switch-w'pers will move also. The right hand endof the side-switch-arm is drawn out into a finger 155, known as the escapement-finger, that works in conjunction with a tooth-escapement to be described: At the base of this finger-a forwardly-bent lug 156 limits the swivel movement of the side-switch-arm, and, therefore, of the side-switch'as a whole, by striking the cam 106 whenever out of its normal rotary position. If the rotary-line-relay is energized the private magnet 160 is energized as a result. This last magnet is usually fastened to a small private-magnet frame that is not shown and which is fastened to the mainswitch frame. Said magnet has an armature 161 that works in a vibratory manner about a horizontal axis that passes through the supporting The said armatureis formed with a forwardly-projecting arm 163 having two flat surfaces n1 an approxi ately portion of the private-arm,

.- shaped upwardly-projecting the shaft is rotated horizontal plane. Furtherm reftheend of thesaid arm is bent at a right angle downwardly and carries certain mechanical details, namely, a lateral arm 164 which is designed to control the relation of the privatesprings 165, 166 and 167 and a tooth-escapement which includes two flexible springs 168- and 169 each of which is riveted by one end to the arm 163, one on the upper side o and the other on the lower. The upper spring is straight and has formed on its end a couple of tooth-projections 170 and 171 which extend downwardly, while the under spring is bent at a right angle first down and then at a right angle to the front. This double angle on the lower spring is so designed that the latter may against which portion said spring rests with a degree of tension. There is space in front of said bent portion to receive two other toothpieces 172 and 173 that are formed on theforward end of the escapement-spring and which are sustained in juxtaposition to the upper teeth,

clear the bent but slightlyto the rear thereof.' A retracting-spring 174, which has one end attached to the private-armature and the other end holds said armature the private -magnet pole-piece. With this construction when the private-magnet is energized once, the private-armature is drawn down momentarily and restored. By this operation the escapement-finger 155 passed first from behind the tooth 17 2 onto the rear of the tooth to the switch frame,

normally away from .170, at the downward stroke of theprivate behind the latter tooth armature, and from at the return stroke. As soon as the escape ment-finger clears this last tooth, the retracting-spring 215 draws the side-switch.

to the second position where it is stopped by the lug 156 striking the cam 106.

When the side-switcli-wipers pass to the second position, leaving the contact-points 175, 176, 177 and 178, and engaging instead with the contact points 197, 198, 199 and 200, the rotary-magnet 179 is energized, this magnet being compos'ed of two coils 180 and 181. The rotating mechanism consists of the rotary-armature 182, a'circuit interrupting arm 183 that works in conjunctionwith 7 two interrupter- springs 184 and 185, the rotary-armature-finger 186 that exercisescertain controlling influences over the privatearmature, and lastly the rotary-arm 187. This arm carries pivotally attached to its forward end the so-calledv rotary-pawl 188.

Said pawl has attached to its rear end a small coiled spring 189, the other end of which latter is fastened to the rotary-arm, and which always restores the rotary-pawl to its normal-position. Upon each rotary step of the shaft the -rotary-locking-armnl lt' I falls behind one of the longitudinal teeth by the rotary-armature retracting-sprin 190. Attention has been called. to the bank; that are located under the switch parts in position before the line-wipers andthe pri-- vats-wipers. The private-contact-terminals are each composed of but one electric conducting piece, but the line-contact-terminals are each madeof two metallic pieces, one over the other and insulated from each the wipers engage with the contacts of their respective banks, the private-wiper. with those of theprivate-ba'nk, and the linewipers with those of the line-bank. After a switch has been operated it can be released by the energization of the release-magnet 137, which energization results if the line relays 119 and 120 are magnetized simultaneously, or if the back-release-relay 191 that controls the bac -release-relay-springs l92and 193 is energized. The circuits that are brought into play under these conditions will hereinafter be more fully explained. When the release-armature is drawn back after the release-magnet loses its magnetizing force, the double-dog is drawn away from the shaft. rotated rests on the shaft-rest 112, as-previously stated, and when left to the back pull of the-coiled spring 118 rotates on the said shaft-rest until the stop-arm 113 strikes the guide-post119 the channel 111 that traverses the circular teeth, and leaves the shaft to fall to its normalfposition by reason of its own weight. The vertical-line-conductor that leads to the first-selector C terminates in the sideswitch-wiper 153, and to the same side switch-wiper the: vertical-normal-conductor 194 is connected, which normal-conductor leads to and terminates in multiple-contacts in connectonbanks'. The rotarv-line conductor. 465, of the same line terminates in the o fi-normal spring 116 which is normally out of contact with the corresponding spring 114, both of which springs are in engagement whenever the switch is off-normal. The spring'll connects with the rotary-side-switch-wiper 154. It will be noticed, therefore, that between the rotaryline-conductor and the rotary-side-switch- ,Wiper 'there'is a contact which is'normally engages with the longitudinal- 'nates banks,

sideswitch'-wiper'152, after passing through er. When the shaft is raised and rotated,

Said shaft when raised and. l

na-l of the battery. If f The shaft-rest then; enters open while the switch is not in use. The rotary-normal-conductor 195, which also terminates in, multiple-contacts in connectorbanks, is connected with. the off-normal spring 116, and is therefore disconnected from the rotary-side-switch-wiper 154. It

evertical andwill be noticed that,'like'th rotary normal conductors 194 private normal conductor 196 in multiple-contacts at and at the selector 0 in and l95, the

' connectorthe privatecertain private normal springs.

.also termi- The side-switch-wipers 151,152,153 and 154:, when in'the second positiomare 11113111 gagement, respectively, with the-l contactf polnts 197, 198, 199 and 200; andwhendn the third position these side-switch-wipers are in engagement with the contact pointsthe Contact? 201, 202, 203 and 204.. Between point/.204 and the rotary line wiper 101 the private-normal-rel'ay 205 is located and provided with an 208, so as to insure. the operations herein armature 206. which controls the private-normal-relay-springs 207 and after described. The firstselectoW-is, in addltion, provided with a bridge-cut-off-relay 209, the armature 210 of power to separate'the springs 211, 212 and 213. The two'former of said springs constitute the terminals of the vertical. and

springs are separated one from the other, thereby opening the bridge formed-between side switch contact-points 177 and 178, th inc-relays, and at the same time interrupting the connection between said relays on the other side and the non-grounded termior any-reason the switch-shaft is raised normal spring closes with the contactpoint 117 a circuit is closed through a' signal-lamp214. The retention of said shaft in a raised condition uselessly is'undesirable since each station that tries to call while it is raised is locked outgfor the time. light signal is designed as switchboard man in charge of the exchange of any irregularity of such a nature.

Fig. 5 shows the connector which has many parts and circuits very similar to'those of the first-selector, and the general movements are nearly identical. The connector may be of the scribedin. Patent No. March 13, 1906, to Keith, Erickson & Erickson. This form of connector was Well known before the date of my application. To the whichre'lay has the bridge-cut-cff-relayrough ,said

general type 'de-' 815,176, granted rotary line-relays 119 and ion vertically disposed switch-shaft 250 are secured the vertical and rotary line-wipers well as the circular ratchet-teeth 257. The

latter are located just above the rotary ratchet-teeth, and are traversed by ,a'longitudinal groove or channel 258, and in order to correspond with the number of levels shown in the bank 259, the said teeth are preferably ten in number, so that the shaft may be given ten successive vertical steps, and so that it may be thus at each step placed at one of the ten levels. At each level, by means of the longitudinal teeth,

said shaft maybe rotated ten steps. The

coiiperatewith the bank-terminals 259, and these terminals are arranged, of course, in ten horizontal rows of ten terminals each, in 4 the usual and well-known manner. The private-wiper 253 is adapted, on the other hand, to coijperate with the bank of privatecontacts 260. At its upper end the said .shaft is subject to the action of a clockspring 261 which has one end secured to said shaft and the other to the stop or normal-post 262, whereby the shaft when ro tated winds up said spring, and whereby when the switch is released said shaft may be automatically restored to its normal position from any position in which it may have been temporarily held;- for the purpose of maintaining any desired electrical connection. The shaft is also provided at its upper end portion with the guide-arm 263 which normally keeps the spring 264 out of engagement with the stationary switch-contact 265, which latter constitutes one terminal of the well-known busy machine F' that is, the machine for producing the current .used for giving the busy signal to a calling subscriber when necessary. Before the shaft is rotated from its normal position, the groove or channel 258 is engaged by the end of the hook-shaped arm or stationary shaft-rest 266; but with the shaft raised to some desired level, and as soon as it is rotated, the circular tooth at such level then slides onto said rest and rotates upon it instead of on the vertical-dog 267. Thus the saidrest acts not only as a bearing, but as a support for the shaft as well.

The vertical and rotary line-relays 268 and 269 are bridged across the trunk-lineconductors 'in' front of the condensers 270 and 271, as clearly shown, with the nongrounded pole of battery B-connected to the said bridge at a point between the two relays 268 and 269. The vertical-magnet 6 272 is controlled by the vertical-line-relay double-dog is said line-wipers 251 and 252 are adapted to .289, 290 and 291, audissubject tute the well-known switch.

rotary-magnet 293 has an armature 29.4 piy= ,mally away from 268 and arranged to operate the verticalratchet-pawl 273, which latter is pivotally mounted upon an arm to the armature 275.

arm 274 is provided with a short L-shaped arm 277 for operating the release-link 278.

The latter, like the release-link of the first- 274 rigidly securedw This armature 275. vibrates about the points 276. The vertical-1 selector, has anopening 27 9' which normally engages the pro ecting pin double-dog 281.

magnet ole-pieces by a retracting-spring.

280 on the, The said; vertieaharj p normally retained away-from the vertical-" The dou le-dog is provided with a. locking member 267 adapted to-engage teeth 257, and also with member 282 adapted .to engage the'longitudinal ratchet-teeth 278. spring tension that tends always to force the circular another. locking 256 whenever... the, released from the release-link The said double-dog'is subject to the said projecting members ordogsinto en= gagement with the said ratchet-teeth, and s.

provided in addition with a-"downwardly- 1 extending arm 283 having a T-shaped end portion 284 adapted to support the '-bifurcated end ofithe link 285, which latter, has

its other end pivotally connected with the end of a rearwardly-projecting member286 on the side-switch-arm 287i The said sideswitch-arm is swingingly mounted and provided with the usual side-switch-wipers 288,v

he so-called to the for-y 292. The sideotally mountedat 295 and-f'carries arigid I arm 296 upon pawl 297 has its support, the latter being pivotally mounted upon said arm 296-. IIt' the end of which the rotary-'- I will be seen that the pawl 273 is adaptedthrough the circular ratchet teeth 257 to actuate the shaft 297 is adapted with the aid of the longitudivertically while the pawl 3 If nal teeth to actuate the shaft rotatively.

Both the vertical and rotary magnets are connected directly with pole of the battery and are controlled by the vertical-line-relay 268, subject, however,'to

the switching action of the side-switch-wiper The so-called private-magnet e298 299, having two 288. provided with the armature flexible springs 300 and 301 whichqa re provided, the upper one with one tooth 303,- and the lower one 'with two teeth 304 and. 305. \Vith the exception of the spring 300; having only one tooth the escapement device of the nongrounded the connectoris identical with that of the All of the armatures ofthe first-selector, are held nor; y their respective magnets ture is pmvided with an insulating piece 307 that engages with the private- springs 308, 309, 310 and 311- as a whole, and which is adapted to flexthe springs 309 and 310 up and down. These two springs are riveted together, but kept from electrical connection by any suitable'insulating material. When the private-armature is depressed the springs 3'08 and 309 are separated and the .retained in contact.

springs310 and311 are pressed into contact; while if the private-armature is raised the reverse occurs with-the .springs 308 and 309 The side-switch-arm 287 is drawn out at one end to form the finger 312 known as the escapement finger and adapted to coiiperate with the escape- Inent-teeth in releasing the side-switch from first to second position, 'in a well-known manner, and then from second'to third position when the private armatufe-is depressed. The release-magnet 313 has an armature 314 adapted, when attracted, to restore the double-dog 281 to its normal position that is,'to a'position where the circular and vertical dogs 282- and 267 are held out of engagement with their respective ratchet-teeth 256 and 257. The side-switch-wipers 291 and- 290 are adapted when shifted to third 5 position to establish connection. between the line-conductors 483 and 482- and the line: wipers 251 and 252, respectively. The ringing-relay 315, by means of its armature 316,

controls through the medium of the ringerrelay- springs 317, 318, 319, 320, 321, 322,

323 and 324 a number of circuits among whiclf are the connections between the condensers 271 and 270 and the wipers 251 and 252. After the connector has completed a call and the ringer-relay is energized when the calling subscriber presses his signalingbutton and by so. doing'removes his own 4 subscriber.

line-conductors from the established circuit and substitutes instead the terminals of the ringer-generator H across the wipers 252 and 251 and hence across the subscribers line for the purpose of signaling the called The side-switch-wiper 289 is adapted when shifted into third position to connect the private-wiper 253 with the grounded side-switch-contact 325. The sideswitch-wiper 288 is adapted when shifted .into third position to connect with the ringer-relay 315, the terminal of which re- .lay is permanently connected to the contactpoint 326.

In Fig. 1 the called first-selector E being identical to the calling first-selector C the parts will be recognized upon reference. The vertical 'and rotary line-relays 401 and 402 are bridged betweenthe side-switoh contact-points 403 and 404 with which the vertical and rotary side-switch line- wipers 405 and 406 respectively engage while the side-switch is in the first position. These two relays are connected normally,

terminates in the while the bridge-cutoif-relay is deenergized, through the" bridge-cutroif-relaysprings 407 and 408. 'At this point where two springs are thus .in contact a third spring 409, connected with the non-grqundbanks in'private-contact-points that correspond to the connector line-bank-terminals in which the normal-conductors 501 and 502 terminate. U'similar normal-line-conductors are indicated at 194 and 195 and the private-normal-conductor at 196.

In Fig. 1 sub-stations #120 and #220 are substantial duplicates of the sub-station #110. Assuming that the four sub-stations shown in said figure have all of their receivers on their respective switch-hooks, as indicated at station #220, then if the subscriber In the first-selector at sub-station #110 wishes to call the subscriber at sub-station #120 he proceeds first to remove his receiver 2 from the hook 3. Said switch-hook is forced up about the bearing 8, and when the ground springs 30 and 31 close into contact the ground post 41 is thereby placed in connection with the groundterminal G The circuit that completes this connection extends from theground post 41 along the conductors 450 and 451, through the ground springs 31 and 30, conductor 452, lock-out springs 48 and 49, conductor 453, to the ground terminal G In the next operation the calling subscriber presses the vertical-button 36 once and the rotary-button 35 once, then again the vertical-button twice, and the 'otarybutton once, and for the last time the vertical-button ten times, and the rotary-button once. In this way, the first-selector C is connected with a connector 1) and the latter is then connected by Way of the first-selector E with a line that leads to the substation #120. When the verticalbutton 36 is pressed once for the first digit the vertical-line-conductor 454 is grounded once, since the spring 38, which is removed from contact with the contact-point 40, is

brought into contact with the groimd post 41. Each time the vertical-line is thus grounded at this stagethe vertical-line-relay 119 of the first-selector C is enersaid tor 456, bridge-cut-ofi-relay-springs 212 and 213, conductors 457, 458 and 459 to the nongrounded terminal of battery B and to ground G. The vertical-line-relay-armature is operated once and presses spring 123 into contact. with the ground spring 124, and

thus .completes a second circuit through the vertical-magnet 126, which energizes the latter. The current in this case passes from the ground terminal'G through the springs 124 and 123 and through the conductor. 460 to the private- springs 166 and 165, thence through the conductor 461, vertical-magnet. 126, conductors 462, .463, 464 and 459 to the.

non-grounded terminal of. battery B and to ground G. The vertical-magnet. attracts its armature l29once and raisesthe shaft 100 one step in the manner already described.

. It may be stated atthis juncture that if the calling subscriber decides not to complete 30' the call he may restore the first-selector thus disturbed, by simply restormgmhe receiver to theswitch-hook.

,. It has been describedthat inits action the switch-hook, through the-arelease-cam-arm 5, as it passes down, flexes the release- I springs 32, 33 and 34 intocontact for a moment. One ofsaid springs-spring 32-has 'the shape, somewhat, of ,an inverted L, and 4 it is so located that'as the cam-arm descends the latter engages the protruding section ofspring, pressing it to one side, and

through itpressing the other two springs 33 and 34150 these three springs causes the rotary and vertical line-conductors .454 and 465 to bo moment rily grounded at the same time. The eff: conductor is already known. :The r6taryline-conductor thus grounded, after the first-selector switch-shaft 100' is raised from its/normal position (by which act the guide-arm 113 permits the springs 114and'. 116 to come into contact) causes the .rotaryline-relay. 120 to be magnetized. 'Theath B of the current through the verticaline-.-' relay, in this case, is from ground terminal G through'the conductor 453, lock-out re-' "lay-springs 49 and 48, conductor 452, ground springs 30 and 31, release- springs 34, 33 and 32, conductor 466 to the contact-point 40.and

the spring 38 to the vertical-line-conductor,' and thence through the vertical-line relayv 119, as above;

The circuit through the rotary-line -'relay extends from the same draw the spring 166 from engagement with q r a moment-into electrical contact." The temporary union -or engagement of,

ct of grounding the vertiealdine ."ipd'ihtd .comesflmagnetized it attracts the release ground terminal G to the release-spring 34 and thence to the release-spring .33 and through the conductors 467, 468 and 469 to the contact-point 39,'over the spring 37 to the rotary-line-conductor 465, ofi-normal springs 116 and 114,- conductor 470, sideswitch-wiper 154, contact-point 178, conductor 471, rotary-line-relay 120, conductor 472, bridge-cutolf-relay-springs 211, 212 and 213, tothe non-grounded terminal of battery B and to ground G. Whenever the rotary-line-relay 126 becomes magnetized its armature, 122, when attracted, fdrces the spring 125 against the ground spring 124, and thus closes a second circuit that includes the private-magnet 160. 'The circuit extends from the ground terminal Gr through the springs 124 and 125, conductors 473 and 474, thence through the privatemagnet 160, and through the conductors 475, 464 and 459, thence to the non-grounded terminal ofl battery B and to ground G. The private-armature being attracted by the private-magnet causes the arm 164 to withthe spring 165 and closesitinstead with the thirdspring 167. Therefore, when the re lease is initiated, the line relays 119 and- 120 become energized simultaneously; and

since the private magnet energizes as a result of the energ'lzation-of the rotary line relay, the energizing'circuit for the vertical magnet 126 .is broken when the. private springs and 166 separate, and, therefore, v the'said vertical magnet 126 does not ener- 1 0 gize at the' release. But as the private spring 166,. which is connected directly with the line relayspring .123, is shifted into'engagement with the private spring 167, the operation of the vertlcal line relay 119 causes the. energization. of the release magnet 137, since the private spring 167 is directly connected to said release magnet. It .is the vertical line relay. 119, therefore, that directly Y causes the energization of the release. niag- 110- net;-'137 by'establishinga circuit from the grounditenninal "G2 -through the ,line-relay- Springs 124' and-.123, conductor 460 to the private-spring 166, asbefore; butfrom'hereitthen' takes a new. pathithrough the lower private-spring 167, to :the conductor 476 amemem to the release-magnet'137, and. thence over-til a 'oonduc'tors 462,'463, 464 and awe 1+ Y grounded terminal'ofbattery? G. Ofcourse, as. already 1 ut,-;.when I said release-magnet -be'-' ar-mature {136 Land. throws the. release link 1'35 Y9 thejiug 140. of thed'ouble dog' 1 41 which, asf 'soonias the release-magnet becomes 1 second position by the retracting-spring 215,-

.returns to its normal from engagement with the circular ratchetteeth 110. The shaft thus being deprived of its only support falls to itsnormal or lowered position and the release or restoration of first-selector be assumed, however, that the subscriber instead of releasing continues his call by pressing the rotary-button- 35 once after the first-selector-shaft has been raised one step. Under such conditions, the rotarylinerelay 120 is then magnetized once by a current. flowing from the ground terminal 1 -130 the ground post 11, thence through the spring 37 to the rotary-line-conductor, and through the rotary-line-relay to the nongrounded terminal of battery 'B and to ground G. The energization ofthis relay causes the magnetizing of the private-magnet 160. Upon the downward strokeof the private-armature 161, the escapement-finger- 155 disengages from the rearmost tooth 172 of the escapement on the private-armature and falls against the upper rearmost tooth 170 from which the said escapement-finger disengages' in turn as the private-armature position. Clearly, at this instant the side-switchis drawn into the and the lug 156 strikes the cam-piece 106, by which means the side-switch-finger is retained between" the ,escapement-teeth 173 and 172.

At the instant that the side-switch-wiper 151 closes with the contact-point 197, the magnetizing side-switch-wiper 151, conductor 478,- the rotary-magnet-coil 181, interrupter- sprin 184 and 185, rota -magnet-coil '180, conductors 463, 465 an 159' to the non-grounded terminal of battery B and to groundG.

The rotary-armature 182 is thus attracted by the rotary-magnet 179 and the shaft 100 is rotated one step by the rotary-pawl 188. At the same time the privatesarmature is depressed by the rotary-armature-finger 186, andvthe interrupter-finger, just as the rotary-armature strikes the rotary-magnet.

polepieces, separates the interrupter.- springs'184 and 185 and thus interrupts the magnetizing circuit. By the time that the, circuit is interrupted,-however, the dog 144:

has engaged with the longitudinal teeth 109,

falling behind the first one of said longi-' 'escapement-finger and the latter then falls into engagement with the upper foremost tooth 171'from which it disengages as soon is accomplished. It will.

circuit through the rotarymagnet 179 is completed from ground G to the contact-point 197, thence through the as the privatearmature is -restored by the" rotary-armature retracting-spring 190. As.

springs will again reeengage andthe energlzin circuit throughthe rotary-magnet would be reestablished were it not that by the time that the reengagement occurs the private-armature escapement has permitted the side-switch to. pass into third position,

no onger in contact withthe contact-point 197. As soonas the side-switch. passes into third necte and, therefore, the side-'switch-wiper 151 isosition the private-wiper 103 is con- A h to ground through the conductor 479,

back-release-relay 19 1, conductor 480, sideswitch-wiper 152, contact-point 202, Y to ground G. This connection to ground provides the private-contact-point with which the private-wiper is connected with guard: ing potential, as well as all other. -rivateconltactoints connected therewith 1n multip e. rotated by the rotary-armature the verticallocking-dog 143 is withdrawn from engag ment with the circular teeth 100 when the said rotary-loo I crest of the longitudinal tooth over which it must pass. But at the same time the rest king-dog rides toward the so t will be seen that as the shaft is 112 moves intov enga 'ment with the circular teeth and: shaft, in lieu; of said yo 7' and remains thus in a support and .bearingas, ong as the shaft is retained initsrotary, laced condition, The side-switch now-being'm-third position and the line-wipers.;being in engagement with the first terminal of the first level of ocking-dog,

es" 1:131 8553011 for the ment, acting as.

the line-bank, thesubscribers line is extend- Y 'ed' to the line-wipers and thence b way of a trunk-line,"'sim1lar to the trunke leadingv from the tenth terminal of the first level of the. line-bank (the conductors 482, 483

and 519 of. which are shown), to an idle 1 connector. However, the-rotation of the shaft 'is not always terminated when the line-,wipers engage with the first set of con-' tacts. Forinstance, should there be atone time ninefirst-selectors each one usin tacts of the first row, for reasons similar to one'of the first nine trunks of the first leve those described in connection with the firstv selector C, when the side-switch of the latter assed intothe third'positio'n, since the si e-switch wiper 152 became. engaged with: the groundedpontact-point 202..

1 the nine contracts of-the levelofthe same-group tobe connected to ground, then when the calling subscriber grounds the rotary side of the line by press- ,ing the rotary-hutton'35 the 'sfid'e-sw itchtrips into second position, ltl'ca n be shown that because the jfirst nine private-terminals are supplied with a guarding potential rotation of the shaft will continu'e until the"wipers ment with the first'contact of the first level of their respective ibanks, and the privatearmature is depressed by the" rotary-armature-fingen and at the same time the interrupter-springs 1845 and 185 are separated by the interrupter-finger 183. The first privatebanlr-contact with} which "the private-wiper engages; at vthe fir'st. step beingconnected .to ground, as. eit'plained, the private-magnet becomes energized. This energizing circuit extends from th e grounded terminallofthe battery B;throughthe'privateetsiiper of the switch that is occupying the first trunk, of

i the first-level and through the bank multiplying conductors to the contact-point with which, the private-w per 103 is, engaged,

thence through the T privatewiper 103, conductor 479, the winding. of the back-release relay 191, ,conductor..{180,, side-switch-wip'er 152, contact-point. 19 8, conductors481 and 474, pv yate magnet 160, conductors 47 5, 464 and-459v to the non-grounded termina -Lei battery band, to ground'Gr'. The privatearmature is thereby retained .depressed, even after the rotary-finger returns to its normal position in response to. the retracting tension ofthe f rotary-armature F retractingv spring 190;- Thenassoon as the interruptersprings;.-rei=lngage the circuit through the;

rotanysmagnet is once more closed and the 'shaft:,is,rotated one more step by; the reenergization oi ithe said" rotary-magnet 179. The private wipennof, course, 'is' driven into engagement with the-second contact of the first level "of'the-private-bank, and the line- Wipers into engagement with-the second set of terminalsof the line-bank; but *still'the privatswip'en meets, another point with guarding potentiaiwhich causesthe privatemagnet; to retain the ,private-arm ;t 1-e attracted even while the 1rotary-a1 ;mature v returns to-i normal ,thus retaining the side'- switch'in its second position. Thus fora second time theinterrupter springs 18 3; and 185 are: separated-by the interrupter-finger, as the rotary-tarmature'is attracted, and the n as the rotaryarmature. 182; returns rgto its normal-position 'once miore the-.interruptersprings closeaztogethere C1ear1y,f, then,; the shaftwill be rotated in a step by step' manher as longgas theprivateewiper continues to meet the grounded ,private-ibank-contacts. Q

After having 'I'Jeen" rotated onto "the ninth contact the private-wiperis rotatedone more step into engagement with the tenth contact of the first level but, this last contact being without guarding potentiahassoon as said private-wiper leavesthe ninth contact, the magnetizing circuit of the private-magnet that has up" to this time held the side-switch in thesecond position is then broken. This occurs atjust about the 'point when the rotary-armature is-at the 'end of its attractive stroke."This being true the privatearmature does not at:;onc' return to its normal position, but follows up the"rotar'yarmature-finger 186 as the-latter returns to,

its normal position. At a given; i t th esc'apement fingerwhich has, during its 0 operation, been resting againsttheforemost tooth of the upper escapement-spring, leaves said tooth, and the side-switch as a whole-is brought tothehird pOsitiOn-bythe sides' witch retracting spring 215, before the interrupter springs 're-engage; -'The -sid eswitch being in its third ipositi'omth'e subonly as far asq-the first-selector sideswitch-wipers 153 and154,'before" the sideits third position, is now switch sprang int line- wipers 101 and 102.

extended .tothe ticallyand' rotated ten points the'subscribers line is not onlyextended to the saidwipers 'hut'through the rotary and vertical contacts 'ofthe tenth terminal ofthe first level to the. trunk-conductors 482 and 483,. and to "thd if connector 3 D, as shown'i'n Fig. '1.

From the [description that has preceded,

it'should be clear that thefirst ground jimpulse to herotary line starts the. selector scribers line which was originallyelite'nded IJTheshaft having been'frai'se'd one step ve'rrotating, which rotation may continue automatically until a. connection is" established with an idle trunk, It will be understood,

also, that if'while therotation of the shaft is taking pl cejthe s bscriber, should decide to check'.the.;progress of his call he'may're- ,"st ore'th'e" first-selector by returning his receiver to its book. As a result, the rotary and. vertical line-conductors, in a familiar 'manner, are grounded. Since the side switch is, however, inse'cond position, and .as the vertical line conductor 4=54:1is-therefore' open at this time, the grounding of the verticalline conductor neednot be consideredj;, but the rotary line conductor a 165, however, is connected with the .vertical-lmerelay 119;throu' hthe'springs 116 and'114,

.conductorl470, 'siders'witch-wiper 1545,. 'contact-point, QOQand; conductor 15 5, and,'si nce 1, 1 private-,magnethwhile the private-wiper is-passing o'v'er' grounded contacts,'is re- .tained magnetizedduring said 'rotatiomjthe 1 private-springs 166and 1 6'.7 .are maintained closed in contact." The switch is released as hi l bws G o nd g the r y 11118 W i e ground G at the sub-station-to the releasespring 33, over the rotary-line-conductor the side-switch is in the second position produces a magnetization ofcthe vertical-line relay while the private- springs 166 and 167 are together, bringing about, as a result previously pointed", out, a magnetization of g the release-magnet 137; The energizing cir-i cuit of the ,vertical-line-relay extends from 465 to the side-switch-wiper 154, through the vertical line-relay 119, and through the bridge-cut-oilf-relay-springs '212 and 213 tothe non-grounded; terminal of battery B and to ground G. Therefore, the releasing from the'energizing of the vertical-line-re contact-points 177 and 19.9 permanently, and

" the selector is released before the opera; tion is terminated, since the private-magnet during said rotation maintains the prlvateof the firstselector while the side-switch 1s 1n second positionthat is, while the rotation of the shaft ,is taking place -results lay at the grounding ofthe rotary-line conductor. This is a novel-feature ofimy invention and one which is desirable. It has been customary to connect the side-switch the contact-points '178 and 200 likewise, the

.vertical-line-relay terminating directly in the first two, and the rotary-line-relay in 'the last two. Then, while the shaft is rotating, and while the side-switch is in second,

position, if for any reason the calling sub; scriber grounds hls vertical-line-conductor springs 166 and 167 in contact, To obviate this difficulty in the first-selector the'contact-points; 17 7 and 199 are disconnected, and the contacts 178 and 200 as well, and be:

sides an extra conductor 494 connects the contact-point 17 7 with the contact-point 200 to enable the switchto perform the release in themanner just described. But after the f first-selector has once operated, and the side-switch is then tripped into third. posi tion', none of the line-relays remain longerin connection with the side-switch-wipers 153 and 154, since there is no connection be-. 1

tween the' adjoining ..contact -points over i which said wipers slide. a After the first selector-shaft has been rotated onto the "tenth contact, and the side-switch has passed. to third position, the calling subscribers line is extended to the. connecto r D over the trunk-conductors. 482- and 483 that terminate in said tenth terminal. Then the release .or restoration" bf said first selector? is attained by. means of .the socalled back-release-relay 191-. Thelines being extendedito the. connector, as shown in Fig. 1,- when the subscriber; again resses the "first button twice, "for. the secon digit,

he. thereby; again grounds .the verticaLline conductor twice,anfdtherebyoperates the- 3 'verticahline-relay 268- of the connector,

twice. This last-ener 'zing the "circuit, begin-f the sub-station #110, extends to the ground post 41, and then passes through the spring 38 and extends over the vertical-line-conductor 454 to the vertical-side-switch-wiper 153 ofthe selector C, thencethrough the contact-point 203, the conductor 484,- and the line-wiper 102, to the trunk-conductor 482, vertical line-relay 268, conductors 485,

486, 487 488, 489 and490 to the non-groundedterminal'of battery B and to ground G.-

- When the vertical-line-relay'of the connector attracts its armature 326, the latter causes the connector line-relay-spring 327 to be pressed against the ground spring 328.

The vertical-magnet 272 is thereby energized twicein consequence, and the connectorshaft 250 is raised two steps. This last en.- ergizing circuit. may be traced from the ground terminal G, through the springs- 328 and 327, the conductor 491, privatesprings 309. and 308, conductor 492, sideswitch-wiper 288, conductor 493, verticalmagnet 272, conductors .487, 488, 489 and 490, to batter B and toground G. Of course, at the rst movement of the verticalarm 274,'the release-link 278 is disengaged from the double-dog 281 by the L-shaped piece 277. The circular teeth at this point, are so raised that as soon as the double-dog is liberated by the removal of saidreleaselink the double-dog retracting-spring rotates the vertical-dog267 into engagement-with one scriber again presses of the ground post 41 to the rotary-lineconductor 465,, thence through the firstselector-spri-ngs 116 and 114, conductor 47 0,-

sideswitch wiper 154, contact point 204, conductor 495, private normal relay 205, conductor 496, rotary-line-wiper 101, rotarytrunk-conductor 483, conductor 497, ringerrelay-springs 324 and 323, conductor 498, ro-

tary-line-relay 269, conductors'486, 487, 488,v

489 and 490, to the non-grounded terminal'of 'rbattery B and to ground terminal G. I When.

the rotary-line-relay is thus magnetized once the rotary line relay armature' 329; is attracted once, which.- latter then "forces the springs 330 and 328 into contact. This last operation closes [a]; magnetizing" circuit through the, private-in'agnetr298. Said circuit' may be traced from' the groun'd termi- TnalG through the springs 328and 33g, con? operation here is once. The escapement-finger, by the tension of the retracting-spring 292, passes, during the attraction and restoration of the pfziyate armature, from behind the escafementetooth 305 to its second position-in rent of said tooth and behind the next tooth304,but not quite in contact with the Patterbecause the cam-lug 3,31 rests against the cam 254;. The the same as that described in connection with the movement of the sidel switch in the first-selectorr. C. The side- ;switc'h' being thus changed from its first to itssecond p0sition, the; side switchwiper I Said relay, upon times, presses the spring the spring 328- again ten times. The rotary- 288ai-is rotated pulsations over p through contact-point 332 onto the' contact-point Now, when the subscriber pressesthe vertical-button- 36 ten times, instead of'the verq magnet 293 is actuated. The ten ground the vertical-linerconductor energizes the vertlcal-line-relay ten times.

magnet is, 1n-this way, energized ten times,

through the circuit that begins with the ground terminal. G and extends, as. above,

the springs328 and 327 to the sideswitch-wiper 288,,thence since said sideswitch-wiper isi-n the second-position through contact-point 333, conductor 500, rotary -magnet'293, conductors 489 and 490 to the-- non' grounded terminal of battery B and to ground G. The armature 29 1 of the rotary-'- magnet is attracted ten tudinal tooth over Of course, it will be understood that by y it is attracted the rotary-pawl engages with one of the longitudinal teeth 256"and rotates the shaft ten steps, one'step at a time, inthe same way that the first-selector rotaryinagnet rotated the firstselectorshaft.

At the first rotary step of the shaft, the.-

shaft-rest 266 en ages with the circular teeth and catches t e shaft-when the vertical-dog 267 is drawn out of engagement with said circular teeth at the time that'the rotary-dog 282 reaches the crest of the longiwhich it hasto pass.

' thetime the "rotary-armature. strikes the the forward rotary action of the shaft the same time that the cir cular teeth pass into engagement; with1the shaft-support 266, the shaftl wipersfimove, onto. the first, conta'ct'of. the second level- 0f I At the second step" onto the secondfcone said. wipers are moved t vvedterminal ofthe battery 13 and to ground 'is retained. At

pole-pieces the said rotary-dog drops into locking engagement with thelongitudinal teeth and provides a', means by. which their respective banks.

. tact of the-same level; andlsoonii Stepiby! L step,i1ntil'they reachthegtenthcontactaThe; 4

from engagement with the tic'al -magnet' being energized, the rotary-' attracting its armatureten 327 in contact with relay-springs the condenser times and each timeside f switch wiper wiper 1253, theme through the;.private-nor mal conductor 507 (through the private nor- I circuit through the rotary-magnet is not in terruptedf by any automatic device like the circuit of tne rotary-magnetof the firstselector; but each energizin impulse through said magnet is pro uced and broken directly by the action of the subsciibenqjust as the vertical-magnet is en'er-' gi zed. The last step of the calling subscriber in completing his connectionis te again ground the rotary line-conductor once bypressingthe rotary-button 35 once; and again the'rotary line-relay is energized, and

again the-private-magnet 298 impulsively attracts its armature once. The 5- tft having been rotated, and the cam 2 having passed out of the way of the cam-lug 331, f

the side-switch, finding no upper front escapement-to'oth, such as the side-switch of the first-selector encounters, passes into thethird position at the depression of the private-armature. In the thirdlposition', of

course, the side-switch-arm rests against the side-switchstop 334, wipers 288,289, 290 a'nd291 pass into engagement respectively 'with' the contact-.

points 26, 325, "336 "and "337. The linewipers having been rotated onto' the tenth set; of contacts: of the second levelbf the bank 259, which set constitutes the terminal "of the normal-conductors 501 and 502, and, therefore, ofthe sub-station #120, are thus put in electrical connection with the desired line. The vertical-line-wiperis connected with the vertical-trunk-conductor 482 by the conductor 503, andthrough the ringer- 318 and 317, conductor 504 and 270 and the rotary-line-wiper 251 is connected-with t e rotary-trunk-conductor 483 through. he conductor 505, ringer-relay springs 321 and 320, conductor 506' and condenser 271. At the instant that the side-switch-wiper 28.9 comes into engagement with the grounded contact 325' a'guarding potential is put on the tenth contact of the second level of the private-bank which contact corresponds with the line-terminal While the side-switchof the called sub-station #120. No other connector may then venture on the said 'line. Furthermore, this guarding potential energizes the bridge-cut-ofi-relay 4:18 of the E,.which relay, by its armature, 'icontrols I the' bridgecut ofi -relaysprings 107,- .408 and 409., The magnetizing current which passes I through this relay comes from :the oun'dedterminal of battery B' togroun -;G .-at the'connector side switch, to the side switch contact-point 325,

' 289, and to the private i'idgecut-oif-relay 418, to the non ground- The object of energizing said relay is to by reason of the Y when the rotary force apart the said springs for the purpose of removin the hon-grounded terminal of the battery B from connection with the vertical-line-relay 401 of the called first-se- 5 lector. Th1 connection between these two lines having been established the calling .party is now ready to signal the sub-station 120. If for any reason the called line had been re bus v-for instance, if any of the sub-stations on the line, assuh-station #220, had been using the "first-selector E, or had any other connector been in connection with the said line-there would have been a guarding po- 15 te'ntial at the tenth private-contact of the second level of the private-bank, said contact corresponding to the trunk-line that leads from the tenth terminal of the second level of the line-bank. Were the said line busy first-selector E being thus in use, the 'said private-contact and, of course, ,all other contacts in multiple with it would'then be connected to ground at the instant that the side-switch of said firstselector passed into third position. The

circuit extends from the said private-bankcontact over the conductor 507 through the private-normalrelay-springs 414 and 413, conductor 508, side-switch 416, to the grounded terminal G. In' the other case,

had some connector called theline in question, the said calling connector, by means of a side-switch-wiper similar to the side-- switch-wiper. 289, when said side-switchwiper is in third position, would connect the prit'ate-wiper and, therefore, the private-contact in question with a source of v guarding potential. ,Suflice it to say, howpressed his rotary-button for the last time,

to cause a switching. operation correspondin to the digit 0, the connector D woul have been released and the calling subscriber would have failed to make the'desired connection; for the releasing-of the connector would have resulted from' the energization of the connector release-magnet 313, the

side-switch being, of course, in the second position, which-1s the position in which the.

side-switch should be before the rotary-lineconductor is grounded" for the last time.

releasing magnet is energized extends from the ground terminal of the battery 3 through paths already described to thetenth contact of the second evelof the connector "private-bank, thence through the private- 9 wiper 253, side-'switch-wiper 289, contactpoint 335, conductor 510, private- springs 310 and 311,.conductors 511 and512, releasemagnet 313, to the non-grounded terminal of battery B and to ground G. Of course, line is grounded by the ever, that had there been such a guarding ergizmg this rela Theconducting circuit over which the said calling subscriber, the private-armature is attracted by the private-magnet over circuitspreviously pointed out, so that the privates rings 310 and 311 are pressed in contact.

he connector release-magnet being energized, the release magnet moves the doubledog 281 in such a manner that the lug 280 on said double-dog is caught and held in the 279 on the end of the release-link openm 278. en the double-dog is thus rotated the. locking-dogs 267 and 282 are withdrawn I from the shaft, which latter is then free to arated from the contact-point 18 and closed m-connectionwith-the contact-point 19. In,

this way the vertical-line-conductor is connected to ground by way of the ground s rings 31 and 30, from the ground terminal and thence to the contact-point 19 and through the ring 17, secondary circuit springs 22 an? 23, contact-point 40, and

s ring38, thence to the vertical-lineeconactor 45 1. The connectoribeing released,

and the side-switch, of course, having been driven by the release-arm 283 back into its first position, about its pivots 345, and with the side-switch- wipers 288, 289, 290 and 291 in en agement respectively with their correspon ing contact- points 332, 338, 339 and 340, and, of course, with the escapement-ifim ger 312 behind the rearmost lower escapement-tooth 305, the efiect of grounding the vertical line is to operate the vertical-linerelay. As above described, the effect-of en at this time is to raise the shaft of the connector vertically, which motion the normal-arm 263 permits the normal-springs 265 and 264 to come into contact. At this instant a busy. signaling current, originating in a suitable device comprising an induction-coil 341;, is sent over the line to the calling subscribers station and through his receiver, said busy signal notiiying him that the desired line is busy. The said induction-c0i1'341 comprises-"a secondary winding'342 into which thebu'sy signaling cu'rrent'is induced.

When the busy circuit is closed with the calling station #110 thecurrent passes from the 0011 342 through the conductor 513 to the contact-point265; thence by way lof the spring 264, conductor 514, contact oint 340, to the side-switch-wiper 291, and t ence throughthe conductor 515, ringer-relaysprings 321 and 320, conductor 506, condenser 271, conductor 483,- rotary-line-wiper 101, private-normal-relay 205,. conductor 495, side-switch-wiper 154, conductor 470,

springs 114 and 116, rotary-line-conductor ice 465, I 37; cOntact-fi int- 39', "condenser 15 ,='receiver 2,"secondary Wiiiding'l of the vertical-line-relay' 268 conduct011sf485 486, i 487, 488 and 489nant1 back again'to thecoil 10 342. But, as-expl ained, instead ofthe call ing subscriber-meeting a'glia 'ding p'otj ,I 1 t i" 1,1, he coi'nplet'eshis connection the ii'tu i er described; and upon proceeding, he presses his signdling-lbntton 16 and the ebygrounds connecting it the vertical-line eondn'ctoi H v "withf the grounte1 minaI through the Springs i d lnc tavj fio n l 1 spr 17, and spfi igs 22 'ang1'23, contacfipoint 4;0 to

' the said w i h line; The Vertical-line being grounded," the 'cbnii'ectoi' "f ivertical 1ine-1'emy 'i'sjfnergi'zed, as 's tated",Yand. its armature ciiises' thelsp 'ings "3 27 and 3281 69 be pressed e sviitch wiper poin -i wnithez h m pj's tionwha m of 'f said s rings energizes the i inger rel ay3lj5'. The 'cfirrent flows .fromtheQfOiihd tei miiml ll. con'n'e'cti andi S 2, the i ingemgenertorli is bridged dii'ectlyfacifoss' the liIlFWiprS 25 1 and 252, and, thefefore,"acroj s's the liiieofthe celled subscriber, with meresmt that the ringer 'atj'th sub-station '#120j fis ener ized, V This perticnl a'rgenerator; er the control. of

h y t a onlyffthelbells {it the ab sg tan on will", nd; If the subsele tqrii which een one of a rent of Whic' 'is' "capablepnlyg offringing 1 con sta ipn V, ionly't s p rovi ed with" fingers that respond thi'ough the condenser 4p2 '7 to the ringeryi28,

spring 432, vertical-line-conductor 517, nordllegi 'fi. different h'enj reached byc v P v29 the: a $1505. nl Tt thW p 5.11 'fr61' n which" point it passes on to the normal:

fcoiidnctor 02, tIien'ceQ t'oQ the linercondnctorfli 516," spring 425, contactrpoint26', thence ith suchimeans and'connections, i1i= u known mein1ier,-..either suhciribef chm-" 11y; and the subscribei -theie"answeitsby re- ,As' soon as, the calling hsiibscfibvep ttgn' 16K the iihgle r.

to press the signalifig- .7

andf the springs relay becomes dener moving his receiver 433Qf'rom the :hook 430,

31 8- and 321, respectively, *ren age ,Vwithl the springs317 ind '320, .it :WhiGh t'wo receivers 2" mid e333 mitt sub-stations 1 LO "%II I(1 "heated in {the same be mmsyem cii'c'uit", beginning Withth'ef veceiv,

' sta rlit the respective be trdced through thegjsecongi ej'. W nding the springs 22 diidfzajt ofthefiieifticzthlineceiver433, contact-.pbint &26, spring 425 to the rotary-linejgc'ondlictorl j 516, thence vover:

482,15 thence onducton w,

line-wiper 251, conductor 505,-1side;s3vvzitch-= ductoi' 496,. pnvate-no maLrelayi205 thence;

465, spring 37,- contzptrpoi'nh39, condenser- 15,1. hack to th'e "receive? 2; Y 1 'Ihe:inductioi1--- uit; omprisi'ng the -trmsmitte comprising the, transmitterAaihvbattery 442 pose of preventing such interference that I terminal G". The switch-hook-springsare is established part of the feature of my improved system will come prominently into use if the subscriber at sub-station #2l0 attempts to make a call. I have found in practice that if two party-lines'similar. to the ones represented in Fig. 1 are connected by means of..vs,witching devices of the character to which my improvement appliesthat-if after the saidconnection is established any one of the remaining substations on either line, by attempting to make a-call grounds either or both of his line-conductors, the. established connections will be broken by' the releasing of the switches employed in making the connection. It is for the purhave provideda non-interfering device, such as the one at substation #210, comprising the lock-out magnet 600. The connection already described being established, if a subscriber at thatstation-station #210+ removes his receiver from its hook, said lock-out magnet will vbe operated so' as to prevent a connection between the ground post60l or the signaling-button-contact 602 or the ground release-spring 603, and ground so adjusted that the springs 604 and which are normally disengaged when the switch-hook is down, as indicated at substation #220, arethrown intoicontact as the switch-hook rises, before the spring 606 is separated from'the spring 6071 Since the first-selector is off-normal the rotary-lineconductor 465, which is normally disconnected fromvthe non-grounded terminal of the battery B, is then connected with said battery through either one of several circuits, depending upon the position of thesideswitch-wiper 154 of the first-selector C, since the rotary-line-normal-springs 114 and 116 are then' in contact. Therefore, there is in which a circuit through the look-out relay 600 is completed, through which circuit 'a current fiows that will operatively -mag-- netizesaid relay. This circuit, when the first-selector side-switch is in the third position, and, therefore, when the subscribers line is extended to the connector, extends from ground- G through the, springs 606 and 607 to the lock-out relay 600, thence through the springs 604 and 605, contactpoint 608, spring 609, through the rotaryline-conductor 465, and thence through the springs 116 and114, side-switch-wiper 154, conductor 495,-normal-relay 205, conductor- 496, rotary-line-wipe'r -101, rotary-trunkconductor 483, conductor 497, ringer-relaysprings 324 and 323, conductor 498, connector rotary-line-relay 269 to the non- .ground'ed terminal of battery B and to ground G. The energization of this look out relay does not take place however until the switch-hook has risen sufiiciently to draw the lock-controlling rod 610 out of reach of the'lock piece 611.

At the instant that the relay 600 is mag- V netized the armature 612 is attracted by the pole-piece of therelay, which armature, as

it strikes the pole-piece, clears the lock piece 1 .611. The latter is forced up in front of said armature in such a manner that the armature is locked against the pole-piece andretained there even after the energizing current ceases toflow through the locking magnet. Said armature, being depressed, causes the spring 613 tobe separated from the spring 614 and thereby interrupts the continuity of the grounding connection from the ground post 601, or the ground contactpoint 602, or the release spring 603, to the ground terminal G even after. the ground springs 615 and 616 are permitted to close. Therefore, the subscriber at the sub-station #210 may work his calling device 'or-press his signaling-button or hang up his receiver without interfering with the connection existing at the time. It is not necessary for the side-switch-wiper 154 to pass into the third position, while the rotary line offnormal springs 116- and 114 are closed in contact, in order that the lock-out magnet of the substation #210 may be energized, should the subscriber at that'station .attempt a call. If the side-switch happens to be in the first position when the attempted call is made, the energizing circuit, instead of passing from the side-switch-wiper 154 to the conductor 495, and thence through the private-normal-relay 205to the iconnector, passes to the contact-point 178 and thence through the rotary-line-relay 120 of the first-selector and bridge-cut-ofi-relaysprings 211, 212 and 213 to the non-grounded terminal of the battery B. -If the at tempted call occurs while the side-switch is in second position the energizing circuit, after reaching the side-switch-wiper 154,

takes still another path which includes the, contact-point 200, the conductor. 494, the

vertical-line-relay 119, bridge-cut-oif-relaysprings 212 and 213 to the non-grounded terminal of the battery B and to ground G. If thesubscriber does hang u his receiver before the subscriber at 'su station #110 destroys his connection with the subscriber #120 the switch-hook 617, upon passing to its normal position, again separates the springs 604 and 605, thus opening the energizing ,circuit through the look-out -magnet 600. Immediately-after said springs are opened, the locking-rod 610 then drives the locking piece 611 out of the way of the 7 locking magnet-armature 612, and the said; armature then returns to its normal, position, restoring the connection between the springs 613 and 614. Since the receiver 618, while the switch-hook is up, is bridged across the line- conductors 465 and 454, the subscriber

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