US2088733A - Printing telegraph system - Google Patents

Description

Aug. 3', 19 37. 3.` WHITE Y 2,088,733

I PRINTING TELGRAPH SYSTEM Filed Jan. 51, 1956 7 sheets-sheet 1 T0 605V SIGNAL ATTORNEY Aug. 3, 1937. C, WHlTE n 2,088,733

4 PRINTING TVELEGRAPH SYSTEM Filed Jan. 3l, 1936 7 Sheets-Sheet 2 /N VEN TOR C. WH/ TE ATTORNEY u 7 sheets-sheet 3 r m L 4 JUE w m IW. mll. wl @um mmm 0 Aug. 3, 1937. c. WHITE PRINTING TELEGRAPH SYSTEM Filed Jan. 51, 193e Aug. 3, 1937. c. WHITE A 2,088,733

PRINTING TELEGRAPH SYSTEM Y Filed Jan. 51, 1936 7 Sheets-Sheet 4 i f2-nh.

E l JQ g 'o "H' l moo o, v j a a Einw LIV d E l o L -l Q5 /NVENTOR L c. WH/rf r v BV ATTORNEY Aug. 3, 1937. Q wHlTE 2,088,733

PRINT ING TELEGRAPH SYS TEM Filed Jan. 5l, 1936 7 Sheets-Sheet 5 /NVENTOR C. WH/.TE

@y WW A TTORNEV Aug. 3, 1937. C, wHlTE 2,088,733

PRINTING TELEGRAPH SYSTEM '7 Sheets-Sheet 6 Filed Jan. 3l, 1956 l ATroRA/Ey Aug. 3, 1937. c. WHITE PRINTING TELEGRMH- SYSTEM Filed Jan. 31, 1936 7 SheeLs-Sheerl 7 NQ@ 3m. so. V D; j

W @n N T/ R H m WW ,L L

Patented Aug. 3, 1937 2,088,733 PRINTING TELEGRAPH SYSTEM Charles White, West Orange, N. J., Bell Telephone Laboratories,

assgnor to Incorporated,

New York, N. Y., a corporation of New York Application January 31, 1936, Serial No. 61,663

6 Claims.

This invention relates to printing telegraph systems and more particularly to those systems which furnish teletypewriter exchange service.

An object of this invention is to provide teletypewriter exchange service in areas having a small number of subscribers, at a minimum cost.

Another object of this invention is to furnish service whereby a teletypewriter subscribers station may be connected through aregular tele- 10 phone switchboard to a tele-typewriter switchboard located at a distant point.

Another object is to multiple the line and trunk circuits through several telephone operators positions without causing interference during communication.

The invention is particularly adaptable for use in areas where the number of teletypewriter exchange service subscribers is so small that it is not economical to provide a teletypewriter v switchboard for this service alone.

According to the present invention, one or more areas wherein the number of teletypewriter subscribers is small, may be connected to a teletypewriter switchboard which is at a considerable distance from the individual areas without the expense of extending the individual subscribers lines for the entire distance between the subscribers stations and the teletypewriter switchboard. The invention provides for connecting A3() any one of the subscribers stations to a-telephone switchboard by operating a key at the subscribers station to light a lamp at the telephone switchboard. The telephone operator may, upon observing the lighted lamp, connect by means 35 of a telephone cord circuit, the calling teletypewriter subscribers line, or line associated with the lighted lamp, to a trunk circuit extending to a teletypewriter switchboard at a Vdistant point. The connection of one end of a cord circuit to a jack associated with the calling line circuit and of the other end to a jack associated with an idle trunk circuit elects the operation. of a crossbar switch whereby the calling 'telegraph line circuit is connected through the closed contact of the switch directly to the selec-ted idle telegraph trunk circuit. The spring contacts of the trunk circuit jack may be connected in engageable relation to a circuit extending to a source of signaling current for supervision, which connection is controlled from the teletypewriter switchboard. Calls from the teletypewriter switchboard may be originated by causing the lamp associated with the trunk jack at the telephone switchboard to light and in response to the lighted lamp, one end of a cord circuit is connected to the calling trunk. The number of the called teletypewriter subscribers station is then transmitted to and recorded on a registering device at the telephone switchboard and the other end of the cord circuit is then connected to the line circuit corresponding to the recorded number. The linking of the cord circuit between a trunk and a line circuit causes the telegraphic circuit between the teletypewriter switchboard and the teletypewriter subscribers station to be established over operated contacts of the telephone subscribers oice.

cross-bar switch at the If all the trunk circuits to the teletypewriter subscribers switchboard are in use when the teletypewriter subscriber initiates a call, or the called subscriber is busy when the teletypewriter switchboard operator attempts to establish a connection, the telephone operator will connect the calling line circuit or trunk circuit, as the case may be, to a busy-back jack for transmitting to the originating end of the connection busy-back interruption.

bya

line which terminates at a telephone central oilice on a cross-bar switch mechanism which is used to connect said line Yover a trunk circuit to a teletypewriter central office;

Fig. 4 shows a circuit termination of the said trunk circuit at the telephone central office;

Fig. 5 illustrates a telephone cord circuit and associated circuit means,

whereby in cooperation with Figs. 3, 4 and 6 the teletypewriter station aforesaid may be connected with the trunk to the teletypewriter central oice;

Fig. 6 illustrates a circuit arrangement which in cooperation with Figs.

3, 4 and 5 may be used to establish a connection with an idle trunk extending to the teletypewriter ofce;

Fig. l illustrates an arrangement of terminal apparatus located at the teletypewriter office for the trunk incoming from the telephone central Fig. 8 is a telegraph repeatercord circuit-'at the teletypewriter central oice;

Fig.'9 shows a teletypewriter station with anassociated line Vextending to and connecting with terminal apparatus located at the teletypewriter central oilice.

In the drawings there are illustrated in comparative detail two teletypewriter stations A and B. Station A is connected to the telephone central oice by two line conductors 302 and 303. Conductor 303 is connected over the outermost left-hand armature of relay 3H, through a resistance 304 to ground, and conductor 302 through the upper Winding of line relay 308 to conductor 3| 1 to grounded positive battery at the left armature of magnet 309. Conductor 3| 1 is a vertical member of .a cross-bar switch mechanism which is used to connect the line of station A over the trunk conductor 404 to the teletypewriter central oflce at which is located the apparatus of Fig. '7, Fig. 8 and Fig. 9. A detailed description of the said cross-bar switch is given in U. S. Patent 2,021,329, granted to J. N. Reynolds on November 19, 1935.

Other incoming lines from teletypewriter subscribers stations, not shown, are connected to other vertical members as 338 and 339. The trunk from the teletypewriter central oiilce terminates on a horizontal conductor 326. Other trunks, now shown, terminate on other horizontals as 340 and 34|. The connection of the line of station A is made to the trunk connected with conductor 326 by the operation of springs 323. In like manner, the line of any station may be connected to any trunk by operating the springs found at the intersection of the line vertical with the trunk horizontal. In order to provide for an all-trunks-busy condition for the line of station A, springs 3|6 are operated which connect vertical 3|1 to busy signal horizontal 342 which connects with a busy signal conductor 336. In like manner other line verticals, 338 and 339 may be connected by springs 343 and 344, respectively, to the horizontal 342. To provide for a line busy condition which may be encountered by a call incoming over a trunk from the teletypewriter oice, the busy signal vertical 336 is associated with contacts such as 331, 345l and 346,Which connect with trunk horizontals 326, 340 and 34| respectively.

In order to eiect the above described functioning of the cross-bar switch mechanism regular telephone cord circuits illustrated by the cord circuit C of Fig. 5 are used. This cord circuit cooperates with the multiple line jacks 504 and 5|| and the multiple trunk jacks, .622 and 630. Each multiple line jack circuit is identied with a line vertical and each multiple trunk jack circuit with a trunk horizontal of the cross-bar switch. For instance, multiple jacks 504 and 5|| are identied with the vertical 3|1; multiple lacks 622 and '630 are identied with the horizontal 326. Other line jacks not shown would be identied with other verticals as 338 `and 339; other trunk jacks not shown would be identied with horizontals 340 and 34|.

To operate the switch mechanism for the line busy condition, a line busy circuit LB of Fig. 5 is provided. When the called line is found to be busy and the calling plug of a cord circuit C is inserted in one of the multiple jacks 53| or 532 the springs 331, 345 or 346 are operated so as to connect to the busy signal vertical 336, the calling trunk corresponding to the horizontals 326, 340 or 34|.

To operate the switch mechanism for the all trunks busy condition an all trunks busy circuit ATB of Fig. 6 is provided. When Aall trunks extending to the teletypewriter oce are found busy and the calling plug of a cord circuit C is inserted in one of the multiple jacks 605 or 640, the springs 3|6, 343 or 344 are operated so as to connect the busy signal horizontal 342 (connected to vertical 336) to the calling line corresponding to verticals 3|1, 338 or 339.

In order to initiate a call to the teletypewriter oice, the switch 30| at station A is operated and the telephone operator in response to the lighted lamp 50| or 50:2, which identifies the line of the calling subscriber, extends the connection over trunk conductor 404 in the manner hereinbefore outlined. A key 4l9 which is arranged to open the circuit for approximately two seconds is then operated. This causes the apparatus of Fig. 7 at the teletypewriter oflice to function so as to light a line lamp 1|6 in response to the operation of a relay 1|4 which operates and locks. Afterv the operator answers by plugging into the line jack 1|9, relay 1|4 releases extinguishing lamp 1|6. For recalling the .teletypewriter operator the key M9 is held open for approximately seven seconds which causes the selector brushes of. Fig. 7 tostep around to the seventh contact so as to connect an interrupter 1|| which flashes a lamp in the cord circuit of Fig. 8. To give a disconnect signal key 4|9 is held open for approximately ten seconds. This causes the brushes 1| 2 and 1|3 to step around to the tenth contact so as to cause the supervisory lamp of the cord circuit of Fig. 8 to be lighted steadily as a disconnect signal. y

Fig. 8 is a preferred form of a standard teletypewriter repeater cord circuit which can be used advantageously in connection with this invention. It is provided with a typing key 8|6, with which the cord circuit may be connected to an operators position circuit 826 in which is located a teletypewriter which the operator may use in communicating with either the called or calling subscriber. For supervisory purposes lamps 840 and 835 are provided. A key 829 is shown which when operated to the right is used to ring the line of erated to the left, to cause the release of a locked-in recall signal in Fig. 7.

Fig. 9 illustrates in conventional manner a standard vstation circuit of a teletypewriter subscriber who is signaled by the operation of a ringerY 920. The .line circuit which is shown is of the open circuit type. The subscriber calls the operator by operating the switch 9|8, thereby causing the lighting of the of the teletypewriter motor 924.

When the teletypewriter operator wishes to call the station of subscriber A whose line terminates at the telephone oiice the calling plug of the cord circuit of Fig. 8 is inserted in the jack 1|9 of a trunk extending to the telephone oice.

By means of a key on the operators teletypewriter an open calling interval of approximately two seconds is transmitted over the line conductor, releasing relay 403, which causes a selector switch to function and effect the lighting of multiple line lamps 603 and 604. 'I'he telephone operator answers by plugging into a corresponding jack 622 or 630, depending upon the positional location of the operator. This causes the operation of a cut-off relay 401, which extinguishes the lamps 603 and 604. The number of the 'line of the called subscriber is then transmitted over a circuit, not shown, tothe telephone oice, `where it is received on a register.

The connection is then completed through the cross-bar switch mechanism by thev subscriber B; when. op-.

line lamp 908 and the starting.

the operators 7,5

' the circuit extending through plugging into a jack 504 or I I, or some other jack, not shown, which corresponds to the vertical which identies the line o the called subscriber. v.

A detailed description of the operation of the invention will now be given. Assuming that the subscriber of station A desires to establish. a connection with station B, switch 30| is operated which starts the teletypewriter motor 305 from a circuit closed through its lower contacts. The upper contacts of switch 30| transfer the winding of the telctypewiter, or printer magnet 33| from ground to line conductor 303. The circuit for line relay 308 which is normally operated, is now traced from ground, resistance 304, back contact and outermost left armature of relay 3| I, over conductor 303, through operated upper contacts of switch 30 I, winding of printer magnet 33 I, normally closed transmitting contacts 330 of the teletypewriter, or printer, at station A, contacts of break key 320, over line conductor 302, upper winding of line relay 300, left-hand contacts of holding magnet 300 to positive battery 333. Line relay 308 releases due to resistance 304 and opens the winding of relay 3|0, which also releases, closing a circuit for lighting the line lamps 50i and 502 which are connected in multiple, and appear, each at a diiierent operators position. This circuit may be traced from grounded battery through the lower armature and back Contact of relay 3I0, back contact and innermost left-hand armature or relay 3|I and lamps 50| and 502 to ground. The operator in control of the cord circuit C, who by assumption is located at the position at which one of the lamps, say lamp 50| appears, observing the lighted lamp 50|, now inserts plug 503 into the associated jack 504 thereby operating sleeve relays 505 and 500 through a circuit from ground, through the winding of relay 505, sleeve contacts of jack 504 and plug 503 and winding of relay 500 to battery. Relay 505 operates relay 3|| from grounded battery on its right-hand outermost armature and front contact, through an obvious circuit and also transfers with its lefthand innermost armature the tip conductor of jack 504 from multiple conductor 528 to multiple conductor 525 and with its left-hand middle armature the ring conductor of jack 504 from multiple conductor 529 to multiple conductor 525. Relay 505 also operates with ground on its lefthand outermost contacts relay 501 which connects the source of audible tone 521 to the conductors 528 and 529 so that, if another operator should now plug into another jack, such as jack 5I I, a busy indication will be received. Relay 505 also opens with its right-hand innermost contacts the normal multiple connection of its Winding withv the winding of the corresponding relay 509 of the adjacent position. This multiple connection is through the innermost right-hand armature and contact of relay 500 and may be extended to corresponding relays of other positions not shown. Relay 505 also connects ground through resistance 5I0 with its right-hand middle armature and contact to the winding of relay 509, through the innermost right-hand armature and contact of relay 509. This resistance acts as a low resistance shunt across the winding of relay 509 which accordingly does not operate if another operator should plug into jack 5|I at another position, thereby avoiding interference With the circuit of jack 504.

When relay 3H operated it disconnected at its innermost left-hand armature and contact conductor SI2' from lamps 50| and 502, which are thereby extinguished. Relay 3|I also connects with its left-hand middle armature and front contact the winding of relay 508 to conductor 3|3, but relay 508 operates only for the short interval during which relay 308 is in an unoperated position. Relay 303 reoperates when its lower winding is energized by the transfer of conductor 303 at the outermost left-hand armature of relay 3II, from its associated back contact to its associated front contact. Relay 30 then reoperates. Relay 3|| also connects at its right-hand inner armature and contact, battery to the winding of cross-bar switch holding magnet 300, which however, does not operate at this time since there is no ground on conducto-r 3|8. When relay 505 operated as hereinbefore described it closed an obvious cincuit through supervisory lamp 5|2 and resistance 5|3. Assuming that key 30| was held operated for only a short interval, lamp 5I2, however, did not light as supervisory relay 5M operated when plug 503 Was inserted into jack 504, and connected a low resistance shunt 5|3 in multiple with lamp 5|2. The operating circuit for relay 5I4 extends from ground through the upper left-hand winding of repeating coil 5|0, tip contacts of plug 503 and jack 504, left-hand, innermost armature and iront contact of relay 505, upper armature and contact of relay 503, resistance 5H, lower armature and contact of relay 508, front contact and left-hand middle armature of relay 505, ring contacts oi jack 504 and plug 503, winding of relay 5i4, and left-hand lower winding of repeating coil 5I@ to grounded battery. The operator now selects an outgoing trunk to the teletypewriter central oice which serves the called station B. The terminal apparatus for one oi these trunks is shown by Fig. 4 and Fig. 6. For the purpose oi the immediate description it is now assumed that all of these trunks are busy. This will be indicated by the lighted condition o1" all busy lamps or" position I, only one of which, lamp 50| is shown. The functioning oi the apparatus of Fig. 4 which effects the lighting of lamp 50| will be hereinafter described in connection with the description for a completed call.

The operator finding that no trunks are available now inserts plug 5|8 of cord circuit C into the busy jack 505 of position I. Busy relay 500 now operates in a circuit traced from grounded battery through supervisory lamp 5|9, resistance 520, sleeve contacts of plug 5|8 and jack 505 and winding of relay 000 to ground. Relay 500 in operating connects ground with its left-hand inner armature and contact to the winding of busy signal selecting magnet Sie, over conductors 001, 52| and SI5. Magnet 3i4 in operating, operates holding magnet 300 in a circuit that may be traced from ground on the armature and contact oi magnet 3I4 over conductor 3|3 through right-hand normally closed contacts and Winding oi holding magnet 300 to grounded battery on the operated right-hand inner armature and contact of relay 3| Holding magnet 309 operates and locks through its right-hand armature and contact to ground on the outer right-hand armature and Contact of operated relay 3II and in cooperation with selecting magnet 3I4 effects the closure of cross-bar switch contacts 3|6, thereby connecting the winding of relay 308 and line conductor 302 to a busy signal cirpuit, not shown, but which is connected to conductor 330. When magnet 309 operated it also removed grounded positive battery 333 at its left-hand armature and contact from conductor 3I1,`thereby leaving conductor 302 free to receive the busy signal impulses, which cause the printing of a distinctive signal at the station A which may be interpreted to indicate the busy condition encountered. Relay 606 when it operated also connected through its right-hand outer armature and contact a grounded busy back interrupter 608 operating at the rate of approximately sixty interruptions per minute to the winding of selector rotary magnet 609, which operates in response to the interruptions and causes the associated selector brush 6I0 to be stepped around I the associated contact arc in the direction indicated by the arrow. After approximately three seconds. brush GIO will have made Contact with the fourth terminal SII closing a circuit from ground on the right-hand inner, operated contacts of relay 606 tlnough the winding of relay 6I2, contact 6| I, selector brush 6|0, and Winding of relay 6| 3 to battery. Relay 6I3 in operating short-circuits the interrupter 608, thereby preventing further stepping of the brush 6| 0. When relay 6I2 operated it disconnected resistance 6I4 from the multiple tip and ring conductors 6 I 5 and 6|6, thereby opening the circuit through the winding ofy supervisory relay 522. This circuit was established when plug 5|8 was inserted in jack 605 and may be traced fro-m battery through the lower right-hand winding of repeating coil 5I6, relay 522, lower normally closed contacts 0f ringing key 523, ring contacts of plug 5|8 and jack 605, lower normally closed contacts of relay 6I2, resistance 6I4, upper normally closed contacts of relay SI2, tip conductors of jack 605 and plug 5|8, upper normally closed contacts of ringing key 523 and upper right-hand winding of repeating coil 5I6 to ground. Relay 522 operated in this circuit and connected resistance 524 in ,40 shunt with lamp 5|8, preventing its illumination.

Now when the operating circuit of relay 522, before traced, is opened by the operation of relay 6I2, relay 522 releases and the shunt 524 being disconnected, permitsy lamp 5I9 to be lighted.

,-45 When busy contacts 3I6 on the cross-bar switch ,5D left-hand middle armature were closed a circuit was closed through the busy signal circuit for holding the upper winding of relay 308 energized. Relay 3I0 having reoperated maintains open the circuit extending through the and front contact of relay 3| I, and winding of relay 508 to battery. Relay 508 in releasing connects resistance 5I1 to the multiple conductors 525 and 526, thereby closing the circuit hereinbefore traced through the winding of relay 5I4, which operates and connects resistance 5 I5 thereby shunting supervisory lamp 5I2 which is extinguished. The operation of relay SI2 also causes through circuit means not shown, the disconnection of the aforesaid busy signal circuit from the conductor 336 which effects the release of supervisory lrelay 5I4 and the lighting of supervisory lamp 5I2. Since several operators have access to the multipled busy jacks it is necessary that the supervisory lamp 5I9 should be dark when the operator plugs in to assure that relay 6I2 has not been previously operated, cutting 01T the busy signal circuit. The operator now observing that lamps 5I2 and 5I9 are lighted will understand that this is a disconnect signal and will withdraw plugs 503 and 5|8 from the jacks 504 and SEE, respectively. On withdrawing plug 503, relay 535 releases, which disconnects battery at its right-hand outermost armature and contact from the winding of relay 3|I, which releases and disconnects battery on its right-.hand inner Vcontacts from the winding of 'holding magnet 309, which releases, opening switch contac 3I6. Magnet 309 in releasing also connects positive battery 333 at its left-hand Varmature and contactv to conductor 3|1 reestablishing the original operating circuit for relay 308 and the key at station A is restored to normal,

505 in releasing dis- 1 by the subscriber. Relay connects ground from the multiple conductor 530 releasing relay 501 which disconnects the source 521 of busy tone from the multiple conductors 528 and 529. On withdrawing plug 5I0, relay 606 releases, opening the operating circuit for the selecting magnet 3I4, which releases, and the circuit through relays 0I2 and 6I3, which also release. A circuit is now closed from battery through the winding of release magnet 6 I 1, closed olf-normal contacts 6I9 of the selector switch illustrated by the contact arc 6I8 and the brush 6I0, left-hand outer contacts of relay 606 and of relay 620 of position 2, thence through corresponding contacts of corresponding relays in other positions, not shown, to the ground 62| associated with the relay of the last position. The selector switch and all apparatus are now restored to normal.

The operation Vof the invention will now be discussed for a completed call from station A to station :B. The Ydescription for an uncompleted call, hereinbefore given, applies up to the point at which the operator observed that all trunks were busy. Finding now that the trunk which terminates on jack'622 in position I is not busy as indicated by the non-lighted condition of the corresponding busy lamp 60|, the operator inserts plug 5|8 of cord circuit C into jack 622, which establishes a circuit through the winding of sleeve relay 623 which may be traced from battery through supervisory lamp 5I9, resistance 520, sleeve contacts of plug 5|8 and jack 622 and winding of relay 623 to ground. Relay 623 operates land connects ground with its left-hand outermost V,contacts to multiple conductor 624 which connects with conductor 40| leading to conductor 320 of the cross-bar switch. Ground on conductor 320 operates through the break contacts of relay 322, selecting magnet 32| which connects a ground to conductor 3|8 operating horizontalL magnet 309 as before described. Spring `combination 323 is accordingly operated, connecting conductor 320 to conductor 324, and conductor 3I1 toi conductor 326, which connects with conductor 402. When conductor 320 is joined toconductor 324 as before described, relay 322 operates and opens with its left-hand armature and contact the circuit of selecting magnet 32|' which releases, and also disconnects with its right-hand armature and Contact negative battery 328 through resistance 321 from conductor 326, which connects with conductor 402. 'Ihe tip line conductor 302 from station A is now extended through to positive battery 122 at the teletypewriter central cnice through contacts of key 4I9, the Winding of relay 403, over line Iconductor 404, conductor 10|, through winding of relay 102, over conductor 103, through the upper outer armatures and their respective contacts of relays 1.04 and 105., and resistance 106. Relay 403 is normally held operated in a circuit from positive battery 405 through resistance 406, the upper outer armatures and their respective contacts of relays 401 and `408, Winding of relay 403, contacts of key 4I9, over conductors 402 and 326, through right-hand armature and contact of relay 322, resistance 321 and negative batteryv 328.

left-hand ground.

lt2! to normal, thereby opening When relay 623 operated, as before' described, relay 401 operated in a circuit from battery on the right-hand outermost armature and contact of relay 623 and disconnected positive battery 405. Relay 493 remains operated on positive battery 122 through the circuit hereinbefore traced. When relay 623 operated it connected, with its right-hand armature and Contact next to the outermost, ground to multiple conductor 625, thereby operating relay S26, which connects a busy tone 621, to multiple conductors 628 and 629, so that, if another operator should plug in at another position, into jack 5319, for instance, a busy tone will be received, indicating that the plug should be withdrawn. Relay 523 also connects the tip and ring conductors of jack G22, over its right-hand innermost 'armature and front contact andthe right-hand neXt-to-innermost armature and vfront contact to multiple conductors 83| and 632. A shunting resistance 533 is also connected with the left-hand middle armature and contact of relay 623 to multiple conductor 835, which connects with the left-hand innermost armatures and their respective contacts of the sleeve relays of the other positions as relay @85, for instance. This prevents the operation of sleeve relays if the operator should plug in improperly, after another sleeve relay associated with the same trunk, has been previously operated.

Relay 601 in operating also connects battery at its lower inner armature and .contactto conductors 409 and E35, thereby operating busy lamps SBZ and busy lamps, not shown, of other positions. Relay 401 also opens at its lower outer armature and contact, the operating circuit o relay 410 thereby preventing its improper subsequent operation when the telephone operator signals out over the trunk to the teletypewriter oice as will be hereinafter described. The operator will now open key lil!! for approximately two seconds, which will release relay 403, thereby re leasing slow-releasing relay 4l2 which connects battery through its back contacts to the Winding of rotary magnet M3 of the selector Switch having contact arcs 4l4 and M5. An interrupter 416 furnishing impulses at a rate of approximately sixty per minute is connected to the magnet 413 and causes the brushes 4I1 and 4|8 to step around in the direction indicated by the arrows. After approximately two seconds brushes 4H and M8 will be resting'on either thelsecond or third terminals of arcs 4&4 and M5. When key M9 is restored to normal, relay 403 reoperates, reoperating relay ll2, opening therebyrthe circuit of magnet cl3, preventing further stepping of the selector switch. A circuitis now closed through the winding of release magnet 420, which may be traced from battery through iront contact and armature of slow-release relay M2, lower operated contacts o oit-normal springs 42| which were operated when the selector switch moved off-normal, winding of magnet 420, second or third contact of arc v415, and brush 418 to This causes the selector switch to rerestore brushes 4l1 and 418 and springs the circuit of lease, to

magnet 42S.

When the key 4l@ was operated relay 102 at the teletypewriter -oce also released, releasing the slow-releasing relay 'm1, thereby connecting battery to the winding of rotary magnet 108 of the selector switch having rotary arcs 109 and 1m. Rotary magnet 188 is also connected to the interrupter 1I i, which causes the switch brushes 1I2 and 1l3 to step around in the direction of y 419 has been restored to normal, relay 102 reoperates, reoperating relay 101 and deenergizing magnet 108, thereby preventing further stepping of the aforesaid selector switch, brushes 112 and 113 of which now rest on the second or third terminals of the contact banks. This closes a circuit for operating relay 1l4 whichmay be traced from ground on the second or third contact of arc 109, through brush H2, upper inner armature and contact or relay 104, winding of relay "H4, and normally closed lower and upper armatures and contacts of relays 105 and H5, respectively, to battery. Relay 1l4 in operating closes an obvious circuit through line lamp l, and locks to ground through its lower armatureV and Contact, under control of relays 105 and 115. When relay 101 reoperates a circuit is closed frombattery on its armature and front contacts through lower contacts of oinormal contacts 111, winding of release magnet 118, second or third contacts of arc 110, and brush arm 'H3 to ground, 'Magnet 1|8 being thus energized causes the restoration of the selector switch to normal. The teletypewriter operator observing the lighted line lamp H5, inserts plug 8M of the teletypewriter repeater cord into jack 119. Relay 105 now operates through a circuit from ground through the winding of relay 105, sleeve contacts of jack' 119 and plug 80| and winding of relay 802 to battery, releasing relay 1I4 and thereby extinguishing lamp 116. 120, traced from battery on the lower inner contacts of relay 105 through lamp 120 to ground. Relay 105 in operating also disconnects with its upper outer contacts positive battery 122 and resistance 106 from the upper outer contacts of relay 104 and line conductor 103. Itv also removes ground `with its upper' inner contacts from the winding of release magnet 1|8. Y WhenY relay 802 operated it also operatedv from batteryon its outer upper contacts, relay 805, which closes local circuits through the windings of repeater polarized relays 804 and 805, which cause thesey relays to operate to their armatures and lefthand, or marking, conta-cts as will now be described. A circuit is closed from ground on the right-hand outer armature and contact of relay 806 through resistances 801 and 808, upper and lower windings in series of relay 804, leftand right-hand uppermost and normally closed contacts of typing key8l6, resistance 811, righthand and left-hand lowermost and normally closed contacts of key 816,'.inner normally closed contacts of relay 818, righthand inner armature and contact oflrelay 806, resistance BIS to negative battery 820. Another circuit is closed (momentarily before relay 805 operates) in multiple with the lower winding of relay 804 which is traced from negativebattery 8|0 (which is identical with battery 820) through resistance 809, armature and right-hand contact of relay 805 to the junction point of the upper and lower windings of relay 804. These windings are so connected that they effect the operation of relay 804 toits left-hand contacts. When relay 805 operates to its left-.hand Contact as will be hereinafter described, positive battery 821 isY connected through resistance 822, left-hand contact and armature of relay 805 to the junction point of` the upper and lower windings of relay 804. Under this condition current flows from A circuit is closed for lighting busy lamp positive battery 82| through the lower winding of relay 804 toward negative battery 820, and through the upper Winding of relay 804 toward ground on the right-hand outer armature and contact of relay 806. The upper and lower windings of relay 804 have each the same number of turns and the same resistance and are connected so that when current from positive battery 82| i'lows as described there is a differential action between the two windings. The electrical constants of the circuits of the respective windings are such, however, that a much greater current flows in the lower than in the upper-winding so that the magnetic effect of the lower Winding predominates. 'I'he direction of current ow in this Winding is such as to operate the armature of relay 804 to its left-hand, or marking, contacts, that is, relay 804 remains o-perated to its left-hand contacts with the armature of relay 805 operated to either its lefthand or right-hand contacts.

In a similar manner relay 805 which is identical with relay 804 operates from negative battery 803 connected to the central junction point between the windings of relay 805 and from negative battery 8|4 in series with resistance 8|5 through the left-hand inner armature and contact of relay 806, resistances 8|| and 8| 2 and momentarily before relay 802 has operated completely,4 through the inner normally closed contacts of relay 802 to the lower winding of relay 805. After relay 804 operates positive battery 838 is connected through resistance 823 and the left-hand contact and armature of relay 804 to the junction point of the upper and lower windings of relay 805. Under this condition the greater current in the lower winding prevails over the smaller current in theopposing upper winding. With relay 802 operated, the lower winding terminal of the lower winding of relay 805 is transferred bythe continuity contacts of relay 802 from negative battery 8|4 to the tip Y conductors of plug 80| and Ajack 1|9, over conductor 103, through winding of relay 102, over conductors 10| and 404, through Winding of relay 403, key 4|9, over conductor 326, left-hand contacts of cross-bar switch spring combination 323, winding of relay 30B, over line conductor 302, contacts of break key 329, normally closed sending contacts 330 of the teletypewriter, winding of relay 33|, left-hand operated contacts of switch 30| over line conductor 303, through the outermost left-hand armature and front contact, conductor 303', through the lowerwinding of relay 308 to negative battery 332. Undery this condition the current-through the line or lower winding of relay 805also predominates and is so directed that the armature of relay 805 remains operated to its left-hand contacts.

The teletypewriter operator in control of the cord circuit of Fig. 8 will now operate typing key8| 6 so that its left-hand uppermost front contacts connect conductor 825 to conductor 824 which extends to the operatorsA position. circuit 826, which is represented conventionally by a box. Inthis position circuit `is a teletypewriter, with which the operator now answers the calling station A telegraphically by actuating relay 804, which repeatsv the telegraphic impulses through the lower winding of relay 805. 'I'he subscriber of station A now types the number of the desired station, causing the operation ofV the relay 805, and the operator, before whom the number is printed, now proceeds to complete the call. Let it be assumed that the line of the called teletypewriter station B is served by the line jack 908, which it is understood, may be joined by multiple connections not shown, with other jacks at other operators positions. The operator will now make a busy test to determine the idle or busy condition of the called line, by touching the sleeve conductor of jack 903 with the tip conductor of plug 821. If the line of station B is busy, a potential will be present on the sleeve conductor of jack 903, which will be extended over conductor 828, through normally closed contacts of ringing key 829, over conductor 830, through uppermost contacts of sleeve relay 8|8, over conductor 83| to the position circuit 826, associated with which is a busy lamp, not shown, which lights in response to the aforesaid busy potential. If the test indicates that the line is not busy then the operator inserts plug 821 into jack 903 thereby causing the operation of relay 8|8, which disconnects the busy circuit conductor 83| from conductor 830, connects battery through its middle armature and contact to the winding of relay 806, and transfers conductor 833 from its connection with battery 820 to the tip conductor 830 which extends through ringing key 829 to conductor 828. The operating circuit for relay 8|8 may be traced from Ibattery through the winding of relay 8| 8, sleeve conductors of plug 821 and jack 903 and winding of relay 904 to ground. Relay 904 also operates in this circuit and transfers at its upper armature and contact, conductor 901, from its connection` with positive battery 905 through resistance 906, to the tip conductor of jack 903; disconnects at its lower innermost armature and contact, line lamp 908 from the armature and contact of line relay 909; transfers with its outer lower armature and contact, line conductor 9|0 from grounded resistance 9|| to a connection with the lower winding of line relay 909. A circuit is also closed for operating the line relay 909 that may be traced from negative battery 9|2 through resistance 9|3, lower winding of relay 909 and outer lower armature and front contact of relay 904, over conductor 9|0, through resistance 9|4, overV line conductor 902, through break key 9|5, normally closed contacts 9|6, winding of printing magnet 9| 1 to ground at the normally closed middle contacts of key 9|8. Relay 909 in operating connects ground to the ring conductor of jack 903, thereby causing the operation of relay 834 in a circuit traced from battery through the winding of relay 834, ring contacts of plug 821 and jack 903 to ground at the armature and contact of relay 909. Relay 834 operated lights the supervisory lamp 835 from battery on its lower inner armature and contact; also connects negative battery 820 through its upper armature and front contact to conductor 833, to replace the battery connection` opened by the inner normally closed contacts of relay 8|8. 'I'his is done so as to maintain negative battery on the line conductor until the called subscriber of station B answers. Relay 834 also connects with its lower outer contacts ground through resistance 836 to the lower left-hand springs of key 829, but this serves no useful purpose at this time.

With the connection established to the line of station B as before described the teletypewriter operator now rings on the tip of the line by operating the right-hand springs of ringing key- 829, which transfers tip conductor 830 from its connection with conductor 828 to a connection with conductor 833 via upper contacts of relay 834 thereby maintaining negative battery on conductor 833. A source of grounded ringing current 831 is now connected through the lower right-hand make springs of key 829 to tip conductor 828, thence through tip contacts of plug 821 and jack 993, upper operated front contacts of relay 984 and winding of relay 999, resistance 9l9, over line conductor 901, through ringer 920, and condenser 921 to ground on the right-hand contacts of key 918.

Answering the ringer the subscriber of station B operates key 918 transferring with its upper springs conductor 922 to conductor 923, thereby short-circuiting ringer 920 in series with condenser 921, and closing with its left-hand contacts a circuit to start the teletypewriter motor 924. Line relay 9119 is now in a circuit from positive battery 821 through resistance 822, left-hand contact and armature of relay 885, lower winding of relay 8M, uppermost normally closed contacts of key 818, resistance mally closed contacts of key 833, through innermost armature and front contact of relay 828, over conductor 838, through right-hand normally closed contacts of key 829, over conductor 828 through tip contacts of plug 821 and jack 993, iront contact and upper armature of relay 98d, upper winding of relay 9119, resistance 919, over line conductor 991, through break contacts of key 925 at station B, over conductor 923, through upper operated iront contacts of key 918, through winding o magnet 911, transmitting contacts 915, normally closed contacts of break key 915, over line conductor 992, through resistance 914, lower outer armature and front contact of relay 984, lower winding of relay 999 and resistance 913 to grounded negative battery 912. Since the two windings of relay 999 are now connected in a series diierential relation, relay 999 releases, opening the operating circuit hereinbefore traced, of relay 834, which releases, extinguishing the supervisory lamp 835, thereby indicating to the operator that the called station B has answered. The subscribers of station A and station B are now connected for teletypewriter operation through the repeater cord of Fig. 8.

When station A transmits a spacing or open impulse the circuit hereinbefore traced through the lower winding of repeater relay 895 is opened, thereby leaving relay 885 energized locally by only its upper winding from grounded positive battery 883 through the left-hand contacts of repeater relay 88d. The direction of current flow through the upper winding of relay 8115 is now such as to operate relay 995 to its right-hand contacts, thereby transmitting a negative impulse from grounded negative battery 819, through resistance 899 and lower winding of repeater relay 884 over the circuit of station B until it meets grounded negative battery 912, which is equivalent to an open circuit or spacing impulse. During the transit of the armature of relay 895 from contact with grounded positive battery 821 to contact with grounded negative battery 819, relay 85111 is energized through upper and lower windings in series aiding from ground on the righthand outer contacts of relay 888 over the line of station B to grounded negative battery 912. The current flow is so directed that relay 894 remains on its left-hand contacts during this transitory period. When the armature of relay 895 reaches right-hand contacts, then grounded negative battery 8111 energizes the upper winding of relay 884 so as to cause this relay to continue on its left-hand contacts. Y

When station A now changes from a spacing to a marking impulse, grounded negative battery 332 is reconnected over the line of station A and acting in series with grounded positive battery 838 reenergizes the lower winding of relay 885, causing the armature of this relay to reoperate to its left-hand or marking contact. In this way the spacing and marking impulses necessary for the teletypewriter message aretransmitted from station A, received by relay 885 and repeated to station B. If the subscriber of the calling station A should desire to recall the teletypewriter operator, this is done by opening the line at station A by means of a timing key, not shown, which maintains an open circuit for some predetermined interval of time, say seven seconds. During this interval relay 388 releases because the energization of its lower winding is insufficient to maintain it operated in a circuit extending to ground at an operated contact on the timing key. Relay 318 releases and relay 598 operates. The operation oi relay 598 disconnects resistance 511, causing the release of supervisory relay 51 and the lighting of supervisory lamp 512. At the end of this interval the circuit will be closed again and the lamps 512 extinguished indicating to the telephone operator that the momentary lighting of the lamp was a recall signal. The opening of the line as aforesaid also effects the release of line relay 683, which opens the circuit of slow-release relay 412, which releases and connects battery to the Winding oi rotary magnet M3, thereby causing the selector brushes 111 and 118 to be stepped around in response to the grounded impulses oi the interrupter 919, which operates at a predetermined rate of approximately sixty interruptions per minute. At the end of the seven-second open period brushes 911 and @18 will have stepped around over approximately seven contacts and relay 193 will reoperate, reoperating relay 412 and leaving the brushes 911 and 118 on the contact to which they were stepped. Brush 411 is stopped on an open circuit contact and accordingly hasno circuit eiect. seventh contact closes a circuit through the upper winding of relay 4138 to grounded battery on the armature and contact of'relay il 1. Relay 88 in operating disconnects with its upper outer armature and contact conductor 68d from the upper outer armature and contact of relay 991, disconnects at its upper inner @fio Brush 118 lon the ,f from ground 2 armature and Contact the winding of relay 118 from brush 811, and connects at its lower outer contacts grounded battery to conductor 489. In

7 relay 1132 releases and thereby releases slowreleasing relay '191 which'closes a circuit from sixty interruptions per minute interrupter 111 through the winding of rotary magnet 188 associated with the selector of contact banks 189 and 110. When relay 192 mately seven seconds, brush 112 will then be on the seventh terminal -of bank 199 and brush 113 on the seventh terminal of bank '118. A circuit is closed from ground through interrupter 11 1, seventh contact oi bank 189, brush 112, inner operated contacts of relay '192, upper closed contacts of ON combination '111, ring conductors of jack 119 and plug 891 and winding of relay 839 to grounded battery. Relay 839 operates in unison with the interruptions of interrupter 111, causing supervisory lamp'ill to hash as a recall signal. A circuit is also closed "for operating relay 184 which is traced Vtrom ground on brush 113, seventh contact of bank 119, upper winding ofrelay 184 and through the armature and conreoperates after approxi-l y70 lighting of supervisory lamp 5|9.

tact of relay 1| 5 to battery. Relay 104' in operating at its upper outer armature and Contact disconnects the upper outer armature and Ycontact of relay 105 from conductor 103 and at its 5 upper inner armature and contacts disconnects the winding of relay 1|4 from conductor 12|. Relay 104, also in operating', connects at its lower outer armature and contacts battery to busy lamp 120. In response to the ashing lamp 840 the operator will operate the left-hand springs of the recall release key 829. This will connect a low resistance 84| in shunt with the winding of relay 105. This shunted circuit is traced from ground through resistance 84|, lower outer armature and contact of relay 839, left-hand upper contacts of key 829, thence through the sleeve contacts of plug 80| and jack 1|9 to the winding of relay 105, which releases. Relay 105 in releasarmature and contact to the lower winding of relay 104 which is held operated through its lower winding, lower inner armature and contact, to grounded battery on the armature and contact of lighted while relay 105 is released. Relay 105 retacts of relay 101 to grounded battery. The brushes 1| 2 and 1|3 are accordingly restored to normal and relay 839 releases. When relay 839 releases, the shunting resistance 84| is removed v from connection with the winding of relay 105,

which reoperates and releases relay 104.

The operator will now operate the typing key 8| 6 to the left, thereby connecting the teletypewriter of the operators position circuit 820 to the line conductor over conductor 824 and will 40 then announce the connection by typing OPR or some other appropriate indication.

If the subscriber of station B desires the attention of the operator the non-locking key 925 is operated which since conductor 90| is disconnected by the break contacts of key 925. As the differential action between the upper and lower windings of relay 909 is accordingly no longer effective relay 909 ground to the ring conductors of jack 903 and plug 821, operating relay 834, which lights supervisory lamp 835 from battery at its lower inner contacts.

When the subscriber of station A has completed the transmission ofy the messagey to station B a disconnect signal is transmitted to the telephone and teletypewriter operators by the operation of a timing key, not shown, which holds open the line kfor approximately ten seconds. At'the end of this period the selector brushes 4|1 and 4| 8 will have stepped around to the ninth or tenth terminal. Brush 4|1 closes a circuit from ground on the ninth or tenth terminal through inner operated contacts of relay 403, upper operated ON contacts 42| and winding of relay 631 to bat'- tery. Relay 531 in operating disconnects resistance 638 from the tip and ring conductors causlng the release of supervisory relay 522 and the Simultaneously with the action just described selector brushes 1| 2 and 1 I3 also step around to the ninth or tenth terminal of their associated banks, due to the release of relays 102 and 101. When re- `7.5 lay 102 reoperates a circuit is closed from ground on the ninth or tenth terminal of bank 109 over brush 1|2, through operated inner contacts of relay 102, upper operated ON contacts 1|1, ring conductors of jack H9 and plug 80| and winding of relay 839 to battery. Relay 839 operates and c lights supervisory lamp 840 steadily as a disconnect signal. After the incoming message has been received at station B, the key 9|8 is reoperated to the olf-position, thereby stopping' motor 924, transferring conductor 922 from connection l0 with conductor 923 to ground, and reconnecting ringer 920 so as to be available for another incoming call. Under this circuit condition line relay 909 is energized through its lower winding alone, the circuit of the upper winding being 15 accordingly operates, connecting lower inner armature and contacts. The operator 20 of subscriber B.

The opening of the line of subscriber A for ten seconds as hereinbefore described, releases 25 relays 308 and 3|0. The release of relay 3|0, operates relay 508, disconnecting resistance 5|1 from the tip and ring conductors and causing the release of supervisory relay 5| 4 and the lighting of supervisory lamp 5|2. The telephone opera- 30 tor observing the lighted supervisory lamps now withdraws plug 509 from jack 504 and plug 518 from jack 622. When plug 503 is withdrawn .relay 505 releases, releasing relay 3| which releases holding magnet 339, restoring the cross- 35 which, in turn, ground from conductor 324, releasing relay 322. The release of relay 5:3-5 also releases the busy tone relay 501. When plug 518 is withdrawn, relay B23 releases, releasing relay 401. Relay 40 401 in releasing extinguishes busy lamps 60| and 692; connects ground through its upper inner armature and contact, winding of release magnet 420, lower operated contacts of ON combination 02| to battery on the armature and 45 front contact of relay 4| 2. The selector switch l now releases. The release of relay 623 also re` leases the busy tone relay 626 and removes ground from conductor 40|. The teletypewriter operator observing the lighted supervisory lamp 50 840 withdraws plug from jack 1|9. The withdrawal of plug 80| releases relays 105, 802 and 839 extinguishing lamps and 84|-0 and clos.- ing a circuit through release may be traced from ground armature and contact of relay 105, through Windling of release magnet 158, lower operated con` tacts of ON springs 1|1 to battery on the armature and front contact of relay 101. The brushes 1|2 and 1| 3 arerestored to normal. All 60 apparatus is now ready for another call.

The operation of the system of the invention tion B initiates a call by operating the switch 9| 8 closing a circuit with its left-hand contacts for the starting of teletypewriter motor 924, and with its right-hand contacts for completing the lay 909 operates through its upper winding in a ..70 circuit from positive battery 905, through resistance 906, back contact and -upper armature of relay 904, upper winding of relay 909, resistance 9|9, over line conductor 90|, normally closed contacts of switch 925, over conductor 75 923, through right-hand operated contacts of switch 9I8, winding of relay 9I1, normally closed contacts 9I6 and 9I5, over line conductor 902, through resistance 9I4, over conductor 9I0,

.through outer lower armature andcontact of relay 904 and resistance 9II to ground. Relay 909 in operating closes a circuit for lighting line lamp 908 traced from grounded battery through lamp 908, back contact and lower ,inner armature of sleeve rel-ay 904 to ground on the front contact and armature of relay 909. The teletypewriter operator observing the lighted lamp 908 inserts plug 821 into jack 903 thereby operating sleeve circuit relays 8I8 and 904. Relay 904 in operating disconnects at its upper armature and contact positive battery 905, and effects the release of line relay 909 by the establishment of a series diierential connection between its upper and lower windings.v This circuit was hereinbefore discussed in connection with the operation of the invention for a call originating at station A and terminating at station B. Relay 909 in releasing removes ground Vfrom the ring conductor of jack 903, thereby preventing the operation of ring conductor supervisory relay 834. Lamp 908 is extinguished, and is disconnected from the contacts of relay `909 by the operation of relay 904. yThe operation of relay BIB closes a circuit from grounded battery through its middle armature and contact and the winding of relay 806, which operates and causes the operation of the armatures of repeater relays 804 and 805 to their left-hand or marking contacts as hereinbefore described. Relay 804 is maintained on its marking contacts due to the predominating effect of the current in its lower winding, over that `of the current in its upper winding.

After plug 821 is inserted into -jack 903 as before described the operator operates the lefthand lowermost contacts of typing key 8I6 and thus connects conductor 842, from the operator's position circuit 826to the tip conductor of plug 821. This circuit is traced from conductor 842 through left-hand lowermost make contacts of key 8I6, front contact and innermost armature -of relay 8I8, over conductor 830, normally closed Y contacts of key 829, tip contacts of plug 821 and jack 903, thence over the circu't of the associated line circuit of station B to grounded negative battery 9I2. The operator now communicates by teletypewriter with the subscriber of station B. The telegraphic current impulses pass through the windings of line relay 909, which, however, does not operate due to the differential action of its windings. Having ascertained that the subscriber of station B desires to communicate with the subscriber of station A, the teletypewriter operator will select an idle trunk to the telephone central office at which the line circuit of station A terminates. The jack 1I9 of such a trunk is arranged to be multipled before several operators positions. The necessary multiple connections, however, are not shown. Assuming that the trunk of jack 1I9 is not busy as shown by the non-lighted condition of busy lamp 120, the operator inserts plug80I into jack 1I9, operating sleeve circuit relays 802 and 105, as before described. Relay 802 connects the lower winding of repeater relay 805 through to tip conductor 103. Relay 105 lights busy lamp 120, disconnects grounded positive battery 122 from the uppermost outer armature and contact of relay 104 and tip conductor 103; removes ground from the lower winding of relay 104; and opens the circuit of magnet 4I3 ymature and contact and tact of relay 506r and.623

operated from grounded battery on the rightthe operating circuit of relay 1I4. The teletypewriter operator will now transmit by means of a key associated with the position circuit 826 an open period of approximately two seconds. Re-

lay 102 now releases releasing relay 101 and .y

thereby closing a circuit through the winding of selector rotary magnet 108 and sixty interruptionsper minute `interrupter 1I I. Brushes 1I2 and 1I3 are now stepped around to the second or third contacts of banks 109 and 1I0, respectively. When the circuit through the winding of relay 102 is closed again after the aforesaid two second interval relay 101 reoperates and closes a circuit from battery through the operated contacts of lrelay 191, lower operated ON contacts 141, winding of release magnet 1I8, through second or third contacts of bank 1I0 to ground on brush 1I3. Magnet 1I8 is energized and causes the release of the associated selector switch, restoring Fig. '7 to the condition existing prior to opening the line for the aforesaid two second interval.

The transmission of the open interval as before described also causes simultaneously the release of relay 403, which releases relay 4I2 and tively. When the line circuit is reclosed relayl403 operates, operating relay 4I2, which opens stopping further rotary motion. A circuit is now closed for operating relay 4 I 0, which may be traced from grounded battery through the `armature and contact of relay 4I I, contact and lower outer armature of relay 401, winding of relay 4I0, contact and upper inner armature of relay 408, brush 4I1 and ground on the second or third contacts of bank 4I4. Relay 4I0 locks to ground on its lower arat its upper armature and contact closes a circuit from ground through the multiple line lamps 603 and 604, each of which are located at a different position. When relay 403 reoperates a circuit is also closed from ground on the .upper inner armature and contact of relay 401, through the winding of releasemagnet 420, lower operated ON contacts 42| to grounded battery on the armature and front con- 4I2. Brushes 4I1 and 4I8 are now restored to the.normal position shown on the drawing of Fig. 4.

A telephone operator observing one of the lighted lamps, 603, for instance, inserts the answering plugA 503 of cord circuit C into the associated jack 622, operating sleeve circuit relays as before described. Relay 401 is hand outermost armature and contact of relay 623, and in operating opens the circuit of relay 4I0, which releases, extinguishing lamps 603 and 604. At the same time the multiple busy lamps y 60| and 602 are lighted over conductors 409 and 636,.-l The teletypewriter operator having selected the trunk of jack 1I9, is now ready to convey to the distant telephone operator the number of the line of the called station A. A preferred method for doing this is by associating with the selected trunk, an independent circuit, extending from ,A the teletypewriter oflice tothe telephone oice, over which.circuit, current impulses of a predetermined characterare transmitted by the teletypewriter operator, using a dial or some other suitable pulsing mechanism. These impulses are Y received on a register circuit, which records the Y register circuit, suitable for the requirementsof vio fof`jack 504 with the number of the caned une. Circuit detaiis of a this invention are well known inthe telephone art, are not necessary todescribe this invention, vand accordingly are notY shown here.

'I'he telephoner operator having determined from a reading of the aforesaid register circuit that a connection with the line of station A .is required will insert calling plug 5|8 into the associated jack 504 after touching the sleeve tip. of plug 5|8 to determine whether or not the called line is busy. This is in accordance with usual telephone practice, and accordingly the circuit details whereby this is accomplished arev not shown. A circuit is now closed for voperating. relay 3I| which may be y traced from grounded battery on the right-hand outer armatureand contact the winding of relay 3| I to ground.Y

When relay 623 operated a.' circuit was closed for operating selecting magnet 32| of the crossbar switch. This circuit is traced fromground 'on the left-hand Iouter armature and contact of relay 623 over conductors 624, 40|, and 320, through left-hand armature and contact of relay 322 and the lWinding of selecting magnet 32| to grounded battery. Holding magnet 309rco`ntrolof relay 505, through ling the vertical inY which isV located spring combination 323 on Vwhich the line of station A terminates, now operatesas before described, and is held fWhen springs 323 are operated, ground on conductor 320 operates relay 322, releasing selecting magnet 32| and disconnecting grounded negative battery 328 from thetrunk conductor 326. The normally vvclosed circuit of station A is now extended over conductors 326 and 402, through key 4|0, winding of relay 403, over conductors 404 and 10 Lthrough winding of relay 102; over conductor 103, tip conductors of jack 1|9 and plug 80|, inner upper'armature and contact of relay 802, lower winding of repeater lrelay 805, operated contacts of repeater relay 804, and re-V 'sistance 823 to 'grounded positive battery 838. The telephone operatorv will now transmit a signal to the teletypewriter operator to signify that teletypewriter VoperatorV knowing /now lthat the it to line conductor 303 connection has been extended to station A will operate the typing key 8|6 to the left and thereby connect the position circuit 826 for teletypewriter transmission and will` call the subscriber of station A by operating the upper case S key of the position teletypewriter which will cause the ringer 350 on the teletypewriterof station A vto ring. Standard commercial teletypewriters areV usually arranged to function in this manner. The subscriber of stationV A will respond by operating Athe )switch 30|Y which disconnects, the winding of printer magnet 337| from ground'and connects .extending tothe telephone `central office, then over the outermost left-hand armature and front contact` of relay 3H, conductor 303l throughv the lower winding '305 and connecting the operated under control of relay 3H.Y

. which' may be vtraced message the send- '7' its lowerwind- 3 which lights the supervisory lamp 835.. Likev wise the subscriber of station A, operates the switch 30| to itsnormal position stopping'motor to ground. To send a disconnect Signal to the telephone and teletypewriter operators'V the subscriberv of station A will operate a'disconne'ct Winding of line relay33| "i or timing key holding the line circuit open-'for approximately ten seconds. before described, the apparatus of Fig.l 4 to'bp'- erate relay 631 and thereby effect Athe lighting of'supervisory lamp 5|2 and the apparatus of Fig. 7 to cause theoperation of supervisory relay 839 and the'lightin'g of supervisory lamp7840."

The telephone and teletypewriter operators observing thev lighted supervisory lamps asraforesaid will remove allplugs ,from their associated jacks, which will result in all apparatusbeing restored to normal as beforedescribed.

In the description just given it was assumed that the line of station A was not busy when the telephone operator tested the line'jack 504. VWhen the' linel of the called station is Afoundtobe busy, plug 5|8 is then inserted finto a Vbusy jack 53|, located in the same position with the line jack 504. Sleeve relay 533 operates in a circuit similar to that described'for relay 505' and connects battery at its right-hand ycloses acircuit for operating holding magnet `335 from grounded batteryon and` 'c ontactj'of relay 334, normally lclosed contacts of the 'inner armature through winding and magnet 335 to ground on thev armature and con-i tact of selecting 'magnet 32|. A busysignal circuit connected to conductor 336 is now connect- .ed .to line conductor 326 throughvrthe operated cross-bar switch contacts 33 1, which causes the printing of a distinctivesignal on 'the'operatofs'E teletypewriter at the teletypewriter cnice.Y When relay .533 operated it also connected theA winding of a selector switch rotary magnet V53i.tov a sixty interruptions per .minute interrupter 531. Afterl approximately three seconds interrupter. brush arm 538 will rest on the fourth terminalof selector bank 539and then a circuit will be closed from grounded battery through; the winding of relay 540, over brush 538, fourth terminal of Vbank 539,

winding of relay 54| to,ground on .the left-hand inner armature and Contact of relay 533. Relays 540 and 54| operate. Relay 540 in operating con- 'n'ects'v ground to lead 542 thereby closing a shunt path around the interrupter lay 54| Yalso operates and disconnects resistance l inner armature and contactl vto conductor 534 operating relay 334. jRelay 334';

'rhis will cause, vas 20 Y 531 and preventing: a further movement of the brush arm 538.

543 from the tip and ringlconductorsof jack 53|,Y

thereby opening the circuit through supervisory relay V522 and causing the lightingA of supervisory lamp 5|ll.V The operation ofV relayv 54 |also dis" connects through circuit arrangements not shown the busy signal circuit before mentioned from the conductor 336, thereby discontinuing the printing of thebusy signal at the teletypewriter'oilice.

VIf, -when'the operator plugs intoy the jack 53|, the;

supervisory lamp 5| 9 should immediately light, this will be an indication that another operator previously has plugged into another jack, such as the multiple jack 532. It will be necessary then for the operator to withdraw plug 5|8 from jack 53| so that with all jacks unoccupied a circuit will be closed from ground 544, through the righthand outer armatures and contacts of all sleeve relays, including relays 545 and 533, the operated ON springs 546 and winding of release magnet 541 to grounded battery. Brush 538 is then restored to normal and when the operator inserts plug 5|8 into jack 53| the busy signal will be transmitted for approximately three seconds until disconnected by the operation of relay 54| as before explained.

What is claimed is:

1. In a printing telegraph switching system, a plurality of subscribers stations, a central oice, a manually operated telephone switchboard at said central cnice, link circuits at said switchboard, a plurality of circuits respectively connecting said subscribers stations to said central omce and terminating in said switchboard, a second central office, a telegraph switchboard at said second central office, a plurality of trunk circuits interconnecting said oices, characterized in this that an automatically operated means comprising a system of coordinate axes at said rst-mentioned. central oflice is arranged to interconnect any one of said subscribers circuits and any one of said trunk circuits under the control of any one of said link circuits.

2. In a printing telegraph switching system according to claim 1 wherein the automatically operated means is a switch of the cross-bar type.

3. In a switching communication system, a plurality of subscribers stations, a central office, a multi-position telephone switchboard at said' central oiiice, a plurality of line circuits each connected at one end to one of said subscribers stations, a second central oftlce, certain of said line circuits each connected at the other end to the first-mentioned central office and the other of said line circuits each connected to said second central office, a multi-position telegraph switchboard at said second central oflice, a plurality of trunk circuits interconnecting said telephone and said telegraph central oflice, a multi-contact switch having coordinately operable elements under the control of an attendant at said telephone switchboard, linking means at said telephone switchboard for effecting the connection of any one of said certain line circuits through the elements of said multi-contact switch to said trunk circuit, and linking means at said telegraph switchboard for effecting the connecting of each of said trunk circuits to any one of said other line circuits for communication purposes.

4. In a switching communication system, a plurality of subscribers sets, a central oice, a multiposition telephone switchboard at said central ofce, a plurality oi line circuits respectively connected to said subscribers stations, a multi-contact switch having coordinately operable elements whereat certain of said line circuits are respectively terminated, a plurality of trunk circuits, respectively arranged, under the control of the operator at said switchboard, to be selectively connected through the coordinately operable elements of said multi-contact switch to said certain line circuits or vice versa, a second central oice at which the other of said line circuits and said plurality of trunk circuits terminate, a multiposition teletypewriter switchboard at said second central office having link circuits for interconnecting any one of said other line circuits and any one of said trunk circuits for telegraphic communication between any two of said sub'- scribers stations. p

5. In a switching communication system according to claim 4 wherein the multi-position telephone switchboard comprises a circuit arrangement fo-r each of said line circuits and each of said trunk circuits terminating at said telephone switchboard, each of said arrangements being common to all the positions of said telephone switchboard, and provided with relay means operative in response to the establishment of a communication connection of any one of said line circuits or any one of said trunk circuits at any one position of said telephone switchboard and signaling means controlled by said relay means and eiectively operable only when another communication connection is attempted at another position connected to an operated circuit arrangement to thereby insure an established connection against interference from any other position of said telephone switchboard.

6. A combined telephone and telegraph system comprising a relatively small number of telegraph subscribers stations, a telephone central oflice, a line extending from each of said subscribers stations and terminating at said telephone central oiiice, a manually operated switchboard at said central oflice having in addition to the usual telephone equipment for handling telephone calls terminals of a plurality of telegraph trunks for extending calls from a calling telegraph subscriber, a telegraph central switchboard for receiving said extended calls, means including cord circuits whereby the telephone switchboard operator may answer an incoming telegraph call and may select an idle telegraph trunk terminal, and means responsive to the operation of the answering and selecting means and. comprising a cross-bar switch associated with the telephone operators position for connecting the calling telegraph subscribers line directly to the selected trunk to thereby extend the call to the telegraph central switchboard.

CHARLES WHITE.

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