US2375794A - Telegraph switching system - Google Patents

Description

May 15, 1945..

F. s. KINKEAD ETAL.

TELEGRAPH SWITCHING SYSTEM Filed March 11, 1942 5 Sheets-Sheet 1 MM "ATTORNEY May 15, 1945.

F. S. KINKEAD ET AL TELEGRAPH SWITCHING SYSTEM 5 Sheets-Sheet 2 Filed March 11 FIG. 8

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ES. KIN/(E140 m/v/v TORS W KLANG W ATTORNEY FIG. 5 q

y 1945. F. s. K INKEAD ET AL 2,375,794

I TELEGRAPH SWITCHING SYSTEM Filed March 11, 1942 5 Sheets-Sheet 3 f." 5. KIN/(5A0 I/VI/ENTORS W K LANG ATTORNEY May 15, 1945. F. s. KINKEAD ETAL 2,375,794

I TELEGRAPH SWITCHING SYSTEM Filed March 11, 1942 5 Sheets-Sheet 4 ES. KIN/(E INVENTORS (k/LANG J W ATTORNEY May 15, 1945. F. s. KINKEAD ETAL ,375,794

TELEGRAPH SWITCHING SYSTEM Filed March 11, L942 5 Sheets-Sheet- 5 W KLA/VG AT TORNEV INI/fiA/TO F5. KIN/(514D 5G1 .[Q v F fi n a a w l O 2st Em 20R x2 20R 1% M50 ot kzmuw w (X m2 Q2. mumum .lHu M 0 2 u HHH M| w M Y 0G0. M M w w w W m I A M P n nev /1 8m fi 3M m b q m 38x3 Bu. Swam m m Qk m2 MGM .llllllll Patented May 15, 1945 UNITED STATES PATENT OFFICE 1 TELEGRAPH SWITCHING SYSTEM Fullerton S. Kinkead, New York, N. Y., and Wilmarth Y. Lang, Towaco, N; J assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application March 11, 1942, Serial No. 434,244

36 Claims.

This invention relates to printing telegraph apparatus and particularly to switching facilities therefor.

An object of the invention is to provide a telegraph line switching systemin which the switching operations are controlled by a telegraph signal receiving instrumentality which is capable of printing or performing switching operations alternatively under the selective control of received signals.

Another object of the invention is to provide a, telegraph line switching system in which a plurality of telegraph stations associated with a telegraph line may be selectively rendered responsive to signals on the line by a signal receiving instrumentality also associated with the line which alternatively records received signals or performs switching operation under the control of received signals.

Another object of the invention is to provide a telegraph line switching system including a plurality of lines over which different signals may be transmitted simultaneously in which one of a plurality of receiving recorders associated with one of the lines controls selectively the response of others of said recorders to signals on said line and also controls the transmission of signals on another of said lines. v

The invention features a telegraph line switching system having relays for controlling the activation of local and remote telegraph receivers and transmitters, the relays being controlled by a fan circuit system which in'turn is controlled by contacts operable by the selector mechanism of a receiving telegraph recorder, the recordin mechanism of which is selectively disabled coincident with the conditioning of the contacts to perform switching operation.

Two principal embodiments of .the invention are contemplated and each embodiment employs as the line switching controlling instrumentality, a combined switching and recording signal receiving selector mechanism of the type disclosed in copending application Serial No. 398,055 filed June 14. 1941, by W. Y. Lang. now Patent No. 2,318,168, granted May 4, 1943. The disclosure of the Lang application is incorporated herein by reference as part of the present specification. Thecombined recording and switching mechanism shown in that application comprises a permutation code signal receiving selector mechanism having a set of selector elements for controlling the selection of character printing members to be operated. The selector elements are also arranged to control a set of switching contacts which are brought into cooperation with the selector elements cyclically for each signal combination received after having been conditioned to be operated. A device for suppressing the operation of printing elements selectively conditioned to be operated by the selector mechanism is provided, and such suppressing device is activated coincident with the conditioning of the switching contacts for operation so that the printing of characters will not accompany the operation of the switching control contacts when those contacts are operated in permutational combinations to perform switching operations.

According to one embodiment of the invention a combined recording and switching mechanism is associated with a signaling line as are also a plurality of repeater for repeating to remote stations signals impressed on the telegraph line. The combined recording and switching instrumentality is always responsive to signals whereas the repeaters are normally inoperative. In the combined printing and switching instrumentality the switching control contacts and. the printing suppression device may be normally disabled so that the instrumentality is conditioned to record characters corresponding to signals received over the telegraph line. A timing circuit controlled by signals on the line is operative in response to a long spacing or break signal to activate the print suppressing device and torender operative the set of switching contactsso that in response to signals followin the long spacing si n al no" characters will be printed but the switching contacts will be operated. The switching contacts are operable in permutational combinations according to the setting'of the selector elements of the signal receiving instrumentality to effect the permutational operation of fan circuit relays which. through their contacts, selectively complete the energizing circuits for individual ones of a plurality of switching relays. Each of the switching relays is operable to render an associated one of the hereinbefore mentioned r repeaters operable in response to signals onthe telegraph-line and such signals will thereafter be repeated to the outlying station controlled by said repeater as long as a holding circuit for the operated switching relays remains effective. Following the operation of one of the repeater controlling switching relays the combined recording and switching receiver is automatically restored to initial condition with the switching mechanism disabled and the print suppressing device also disabled so that normal recording operations will thereafter occur in response to long spacing signal whereupon the reception of a particular signal assigned to disabling of the repeaters which control remote stations will operate the switching contactsto complete tl'ie energizin'g circuit for a relay which will. interrupt the holding circuit of any of the repeater controlling switching relays that had been operated, thus restoring the repeatersand the switching relays to inactive condition.

In accordance with another embodiment of the inventionthe combined: recording" and. switching instrumentality is normally conditioned to' per form switching operations and to suppress printing. The system of switchin relays contained in this embodiment oi the invention. includes areiay'ror'disabling the switching contact mechanism without? disabling: the print suppress-ing device so that when the particular switching re"- lay has been operated and is maintained: operated'by its locking'circuit the combined recording and switching in'strumentaiity will." neither record nor' perform switching operations in re sponse to signals on the line: Included: among the switching'relays' is arelay which when operated' will disable the switching mechanism and also disable the print suppressing" mechanism of the combined recordingand switching instrumentdli'ty so that it will record received signals" but such signals will" not be: effective to control the switching mechanism. There is alsoat least one switching relay: which will conditiona repeater to respond to signals on the receiving line and repeat such signals to a remote printing telegraph receiving device:

The switching mechanism is arrangedto controlselectively a plurality of? switching relays for starting any one oi a plurality of transmitters, some: or which may be remotefrom the station at which the combined recording and: switching instrumentality is located; to cause such transmitter'to impress telegraph signals on a transmitting line which constitutes a separate line from the receiving line and over which different sets,

of signals may be simultaneously" transmitted. Iii connectionwitn the starting" 01 transmitters the system is so arranged that any repeater which has been conditioned to reospond' to signals on tile receiving line for repeating suclrsignals to a remote recorder is disabled during the reception of the transmitter start controlling signals without disabling the switching relay whichcontrols that repeater so thatthe repeater will not respond to the transmitter start controlling signals but will respond. after the transmitter has. been started and transmission of normal message sig. nals" intended for the remote station controlled by the repeater'hasbeen resumed.

For a complete understanding, of the invention reference may be had to the following detailed description to be interpreted in the light of the accompanying drawings wherein:

Fig; I i's-a schematic perspective view of a com-- bined recording and switching instrumentality forming a part or the present invention;

Fig; 2 is averticai'sectionalview through the combined recording and switching instrumentality showing the switching contact qualifying and operating mechanism and the printing bail blocking mechanism;

Figs. 3, 4 and 5 are fragmentary elevational views, partly in section, showing the switching contact qualifying mechanism in successive stages of operation;

Fig. 6 is a circuit diagram of a line switching system according to one embodiment of the invention, the complete system being shown by combining Fig. 1 with Fig, 6 with the former positioned below the latter, as indicated in Fig. 9;

Figs. '7 and 8 when placed end to end with Fig. 7 at the right of Fig. 8 form a circuit diagram of aline switching system according to another embodiment of the invention and a complete system is shown by combining Fig. 1 with Figs, 7 and 8 with Fig. l positioned below Fig. '7, as indicated in Fig. 10.

Reiem-ing now to the: drawings, Figs. hand 2 show: a. combined. recording: and. switching instrumentality which is generally similar to that'dis closed in. copendi'ng application Serial No. 3%,055 filed. June. 14, 1941, byw. Y. Lang. Referring now particularly to Fig. 2, the reference numeral N indicates a; selector magnet the armature II of which is carriedby a selector lever l3 pivoted at I. As is iull'y disclosed in Patent 1,904,164 granted April 18, 1933, to F. Morton et 51., the disclosure: of which is incorporated herein byreierence as part of this specification, since that patent shows. a printing telegraph receiving device; to which features of the present invention have been added, the selector lever ll'controls a plurality ofsword levers l6 which are mamaually articulated to bell cranks l1 pivoted at I! and: individually rocked in counter-clockwise direction once in each receiving cycle by a. cam l9, one" 01. which is shown in Fig. 2, included in a receiving'selectoir cam assembly mounted on and irictionally driven by a power driven shaft 2|. Upon being retracted by their .bell crank levers H the sword-lever I8 are rocked into extreme clockwise or counter clockwi'se position depend"- ing upon. the position of selectorlev'er l3 as determined by selector magnet ii, and when they are shifted rightwardly by their bell cranks" IT as thebell cranks are restored to extreme clock- WiSe position. by their'individual' springs '22, the sword levers rock associated T levers 23 into extreme clockwise or counter-clockwise position depending" upon. the rotative position into which they have been rocked under the control 01' the selector magnet. The T levers 23 are articulated by means of disc and slot connections to individual selector vanes 24 that are pivotally supported at their opposite ends by trunnions ZBiFigs'. 1 and 2). l

A movable type basket, lull structural details 01" which are shown in the Morton et a1. patent. supports permutationally notched code bars" 21 that are ind'ivdually connected to the selector vanes 24' by bell cranks 28, a portion of on'e of which is shown in Fig. 2. Theupwardly extending arm of each bell crank 28 engages one oi the code bars 21 and a laterally extending arm of each bell crank 28 terminates in a bifurcated portion 29* which straddles the edge of a selector vans and remains in engagement with the vane while moving along its edge as the type gasket movesfor character spacing and carriage etui'n operation. The type basket pivotally supports a plurality of type bars 3| which have rack and pinion connection with individual selectable pull with a blade 33 carried by a reciprocable printing bail 34 which is mounted on the type basket. Each of the pull bars 32 is provided with a hook 35 near the upper end of the sloping cam surface I so that when the printing bail 34 is reciprocated rightwardly as viewed in Fig. 2 and the righthand ends of the pull bars move downwardly into engagement with the code bars 21, any pull bar which finds an alignment of notches presented to it by the code bars will move still further downwardly at its right-hand end into the alignment of notches, bringing its hook 35 into the path of blade 33 of printing bail 34 so that as the bail continues to be moved farther to the right blade 33 will engage the selected pull barand reciprocate it rightwardly thus rocking the associated type bar 3| in counter-clockwise direction to bring its type carrying face into printing engagement with paper carried by a printing platen 36.

Printing bail 3'4 is provided with 9. depending stud 3'! which rotatably supports a roller 38 disposed between a pair of blades 39 supported at the upper end of a printing bail operating arm 4|. The roller 38 and blades 39 provide for operative engagement between printing bail 34 and operating arm 4| throughout the path of travel of the type basket by which printing bail 34 is supported. Operating arm 4| which is supported on rock shaft 42 is urged in clockwise direction by a tension spring 43 which supplies the power for operating the arm 4| and thus the ball '34.

'A printing cam 44 which is included in a main cam assembly carried by the shaft 2| is engaged by a roller 46 (Fig. 1) carried by a pivoted lever 41, the upper end of which supports an abutment screw 48 which engages the right-hand one" of the operating arm blades 39 as viewed in Fig. 2. The cam 44 operates through lever 4! to restore operating arm 4| to extreme counter-clockwise to extreme counter-clockwise position which in turn restores bail 34 to its unoperated position.

Although only one printing bail operating arm 4| has been referred to in the foregoing paragraph it will be understood that there are at least two such arms located near the ends of rock shaft 42 and that there may be others inter mediate those two. Associated with the end ones of the arms 4| are brackets (Fig. 1) interconnected by a bar 52 and supporting the ends of a function selection control rod 53 which-extends parallel to the axes of the selector vanes 24. At the rear of the vanes 24 a plurality of selectable function levers such as the levers 55 and 5! are pivotally mounted on a rod 58. Each of the selectable function levers is provided with two spaced upwardly extending arms. The arm of the selectable function lever that is nearest to the rear edges of the selector vanes is provided with permutation code combinations of lugs in registry with marking or spacing positions of. the

rear edges of the selector vanes in :inverse rela tion to the code to which the function lever is to be responsive. When the selector vanes are positioned in accordance with the code'to which the selectable function lever is to be responsive, their rear edges are out of registry with the lugs and the function lever is not blocked but is free to rock in clockwise direction as viewed in Fig. 2. However, the rocking of the function lever is normally prevented by bar 53' carried by brackets 5| associated with the print bail operating arms. The rod 53 cooperates with a cam portion of the rear arm of the function lever. When the print,- ing bail operating arm 4| is operated by spring. 43 the rod 53 moves downwardly along the surface of the rear arm of each function lever and permits the function-levers to rock in clockwise direction .as viewed in Fig. 2 to test the setting of the selector vanes 24. Any function lever which finds no selector vanes blocking its lugs will be rocked in clockwise direction by associated spring 59 to perform or initiate its assigned function as the case may be. The printing bail bar 52 carries an upturned flange 55 which overlies the top of the rear arms of selectable functionlevers 56 and 51 and-which moves down into engagement with the top of the rear arm of either of those levers when they are selected, the purpose of the flange being to block the printing bail mechanism after it has operated far enough -to permit the selection of the function levers, in order to suppress operation of any pull bar 32 that may also be selected. i Those functions which require more power for their performance than the springs 59 can supply or the performance of which should be prolonged over a greater interval than that involved'in the rocking of its function lever to the extreme clockwise position as viewedin Fig. 2 are performed by a function bail 6| supported'by operating arms 62 journaled on rock shaft 42. Associated with one of the function bail operating arms is a cam follower lever arm 63 which supports at its free end a roller 64 which engages cam 66 included in the main cam assembly. When the main cam assembly is rotated the function bail operating arms 62 are ositively rocked in slightly counter-clockwise direction by spring 61 under control of cam 66, then in clockwise direction as viewed in Fig. 2 by cam 66 and thereafter the function bail 6| is restored to normal position. which is short of extreme counter-clockwise positlon, by spring 61. The manner in which function bail 6| operates function performingmembers will be described hereinafter; I Referring now to Fig. 1, it will-be noted that a cradle 1| consisting of a flat plate 12 and parallel arms 13 is pivotally supported by trunnions 14 which engage arms 13 near the inner end thereof. Extending between and supported by the outer ends of arms 13 is a pivot rod 16 which pivotally supports a plurality of bell cranks 11 in align ment with the marking positions of fingers l8 integral with and extending rightwardly from the right-hand ends of the selector vanes 24. The free end of one arm of each of-the bell cranks Tl is aligned with the marking position of the fin gers 18. The plate 12 of cradle 1| supportsa plurality of pairs of normally open electrical contact springs 19, there being a pair of electrical contacts assigned to and aligned with the other arm of each of the bell cranks 71.

Cradle H is provided with an perating arm 8| which is connectedby spring 82with the free end of a laterally extending arm 83 of a, pusl l bar 84; 1 Push bar84is mounted for reciprocable movement leftward1y,-as .viewed ixrF-ig. 2, by pin 88' which passes through a slot in push bar 84. The push. bar 84-is urged to its extreme forward position- (rightward position as viewed in Fig. 2) by a compression spring8'l which is disposed in thekslot. through which pin 88 extends and which is confined between pin 88 and the opposite end of the slot. A tension springv 88 which is connected to push bar- 84', isdisposed above thepush bar and extends rearwardly from the point of connection thereto, imparts a counterclockwise moment of torque thereto-tending to lift the foremost (right-hand as viewed in Fig. 2)

' endof the push bar.

function bail 8i when the bail is inextreme forward position. Push bar 84 is arranged to be heldinsuch position that its shoulder 89is-be10w and therefore out of the operating path f: b1ad 9|: of the function bail by means of a pin 92 (Fig. 3') loosely extending through a depending arm 93 carried by the lower armature lever 94 of an electromagnet I I2, the pin being carried by a leaf spring 98 secured to the arm 93 of armature lever 94.- When electromagnet H2 is deenergized a tension spring 91 rocks armature IeVGr 94 about its pivot pin 98 into extreme clockwise position as viewed in Figs. 1, 3, 4 and 5, with the end of the depending arm 93 resting against the inner or right-hand side of push bar.84. In this condition of the apparatus pin 92 extends overthe top of push-bar 84, the upper edge of which is rocked into engagement with pin 92 by tension spring 88 and the pin holds push bar 84 in such position that shoulder 89 is held clear of the function bail blade 9i. Push bar 84 has secured to the right-hand side thereof as viewed in Figs. 3,4 andv 5 a cam plate 99 the contour of which is-shown in dotted outline in Figs, 1 and; 2. The position of cam plate 99 on push bar 84 is such that'whe'n the push bar is in the extreme forward position. (right-hand position as viewed in Fig. 2) the hump or apex of cam plate 99will be disposedentirely to the right of the free end of depending arm 93 of armature lever 94. The height ordepth of the hump or apex portion of cam plate 99 issuch that when push bar 84 is held down with its upper surface resting against pin 92 the highest portion of the hump orapex of cam plate 99 is slightly above the lower end or extremity of arm 93' of armature lever 94. The amount of travel of. push bar 84 leftwardly' under the control of function bail blade 9i as viewed in- Fig. 2 is sufiicient to bring the highest portion of camplate 99 into alignment with or even slightly to the left of the lower end or extremity of arm 93 of armature lever 94.

The locked out condition of push bar 84 described hereinbefore is shown in Figs. 1,, 2 and 3. Upon the energization of electromagnet H2 armature lever'94 is rocked in counter-clockwise direction, as viewed in Fig; 3, into the position shown in Fig. '4' and in being so rocked the depending arm 93 of armature lever 94 is retracted away from engagement with the right-hand surface of push bar 84 and out of the path of cam plate 99 and in being so retracted pin: 92 is drawn out of blocking relation to push bar 84. When the push bar thus becomes unblocked tension spring 88 rocks the push bar 84 in counter-clockwise direction thus elevating the'right-hand end as: viewed in. Fig. 2 and such counter-clockwise movement continues until the base of the notch which provides the shoulder 89 comes into engagement with function bail blade 8! thus presenting shoulder in the path of the function bail blade.

When the function bail is thereafter rocked in clockwise direction by function cam 88, pushbar 84. will be moved leftwardly as viewed in Fig. 2 thus compressing. spring 81 and when. incompleting its cycle the function bail is restored to extreme. counter-clockwise position by tension spring 81 push bar 84 .will be restored to extreme right-hand position by compression spring 81. It will. be understood that compression spring81 is considerably stronger than tension spring. 88 so that itis. capable of restoring push bar 84 to the extremeright-hand position which restoration is in fact opposed butnot prevented by' tension spring 88.

As long as the apparatus remains inthe con clition shownin Fig. 4 withv electromagnet H2 energized push bar 84 willv be reciprocated. each time the function ball is operated. However, when electromagnet H2 becomes deenergized, tension spring 91 will seek to restore the armature lever 94 to extreme clockwise position and will accomplish this result if push bar 84 is then in extreme right-hand position as viewed in Fig. 2. If push bar 84 should be undergoing a cycle of reciprocation at the time that electromagnet H2 becomes deenergized, tension spring 91 will rock armature lever 94 in clockwise direction until the depending arm 93 of the armature lever comes into engagement with the right-hand side. 0! cam plate 99 as viewed in Fig. 4. This condition will occur because push bar 84 is at this time rocked into extreme counter-clockwise position and the uppermost portion of cam plate 99 will be considerably above the lower end of arm 98 of armature lever 94. However, when push bar 84 returns to extreme right-hand position as viewed in Fig, 2 tension spring 91 will bring depending arm 93 of armature lever 94 into engagement with theright-hand surface of push bar 84, as shown in Fig. 5 with the lower end of the armature lever to the rear of and below the uppermost portion of cam plate 99 and with pin 92 shifted rightwardly with respect to arm 93 of armature lever 94,'the leaf spring 98 yielding to' permit this movement of pin 92. This is the condition of the apparatus shown in Fig. 5.

Upon the next reciprocation of push bar 84 by function bail blade 9i cam plate 99 will come into engagement with the lower end of armature lever arm 93 and riding against the lower end of the armature lever will cause push bar 84 to be rocked in clockwise direction as viewed in Fig. 2 a sufficient distance for pin 92 to clear the upper edge of push bar 84 and to be thrust into blocking relation to the push bar by leaf spring 86.

Shoulder 89 of the push bar 84 will thus be disengaged from function bail blade 91 and the push bar will at once be restored to the initial condition shown in Figs. 2 and 3, namely in extreme right-hand position and with pin 92' holding push bar 84 out of cooperation with function'bail blade 9|.

When the function bail blade 9! engages. shoulder 89 and reciprocates push bar 84 rearwardiy of the printer (leftwardly as viewed in Figs. 1 and 2), arm 83 of push bar 84moves rearwardly with the push bar and imparts through spring 82 clockwise movement to cradle H as viewed in Fig. l. .The pairs of contact springs 19 carried by the cradle II are moved in an arcuate path about the trunnions I4 as an axis, and since the bell cranks 11 are held in engagement with their respective contact springs by tension springs I5, which exert insufiicient tension to close the springs, the bell cranks 11 are moved arcuately in clockwise direction about the axis of trunnions I4 without rotation on their own axis. After the bell cranks I! have been rocked through a very short angular distance, those of the selector vanes 24 that are then presented in marking position will block, by means of their fingers I8, further arcuate movement of the bell cranks 'I'I associated therewith. As the cradle II continues to move to its fully operated position with certain of the bell cranks TI blocked by the selector vanes 24 the corresponding electrical contact springs yield in order to be further moved while their bell cranks are blocked, and in so yielding the contacts are closed. In this way the closing of pairs of contacts I9 in permutational combinations corresponding to the setting of the selector vanes 24 may be accomplished.

Electromagnet H2 is energizable over a circuit and under circumstances which will be described later, to attract its lower armature lever 94 for the purpose of conditioning push bar 84 to be operated and also to attract its upper armature I 24 which is carried by a lever I I6 pivoted at I I1 and biased in counter-clockwise direction as viewed in Figs. 1 and 2 by a tension spring H8. Lever H9 pivotally supports a lever H9 which is provided with a latching shoulder I2I for the left-hand one of the printing bail operating arm blades 39 as Viewed in Fig. 2 and with a pointed or tapered end, Lever I I9 is normally maintained in a position extending longitudinally of magnet controlled lever 8 I6 by means of a tension spring I22. When magnet H2 is in deenergized condition spring H8 holds lever H6 against a stop I23 with shoulder I2! of lever H9 out of latching or blocking relation to the print bail operating blade 39. When electromagnet H2 becomes energized it rocks lever H3 in clockwise direction to bring shoulder I2I of lever I I9 into a position below the upper edge of the rearmost blade 39 of the print bail. If the print bail operating arm M is at this time in its normal or unoperated position, the shoulder I2I of lever H9 will be disposed in the path of blade 39 so as to prevent the movement of the printing bail to its operated position which, it should be remembered, is permissive since the bail is operated by spring 43 and is restored by cam 44. If at the time magnet H2 becomes energized the printing ball is partially or fully operated some portion of the tapered or pointed end of the lever H9 will drop into engagement with the top of blade 39 or into the return path of that blade and when the printing bail is restored to its normal or unoperated position the lever H9 will be cammed in counter-clockwise direction by the cooperation of its tapered end with the upper edge of the blade 39 until the blade has been moved clear of shoulder I2I. The rocking of lever H9 by blade 39 causes spring I22 to become distended and as soon as blade 39 clears shoulder I2I the spring I22 will restore lever H9 to its normal relation to lever I I6 thus presenting shoulder I2I in the path of blade 39 to block the printing bail 34. Thus as long as electromagnet I I2 remains energized lever H9 remains in blocking relation to the printing bail operating mechanism so that the printing bail cannot be operated to effect printing. It should be noted that the full operating stroke of the printing bail 34 is not blocked but only that it is blocked sufficiently short of its full stroke to prevent its blade 33 from engaging the hook on any selectable pull bar 32 that may have been selected. The partial stroke of printing bail operating arm 4I that-is permitted before blade 39 comes into engagement with shoulder IZI of blocking lever H9 is sufiicient to permit rod 93 to move downwardly along the cam surface of the rear (left hand) arms of the selectable function levers such as 56 and 51 to permit the function levers to test the setting of the selector vanes 24 and tOpermit the selection of any such function lever which is not blocked by the selector vanes.

Instead of providing for blocking of the printing bail by cooperation of shoulder I2I of lever H9 with one of the blades 39, the lever H9 may be arranged to cooperate with and block one of the printing bail operating arms M. For example, the magnet I I2 and lever I I6 may be mounted lower in the printer to present the pointed end of lever H9 in alignment with an aperture out through a print bail operating arm 4|. With the arm M in the normal or retracted position the foremost or pointed end of lever H9 would extend through the aperture in the arm 4| with the shoulder I2I in position to be dropped into blocking engagement with the arm 4|. As in the structure shown in Figs. 1 and 2 the pointed end of lever H9 would guide the lever into the aperture upon retraction of arm M from its operated to its unoperated position.

The armature operated lever H6 is provided with a depending lug I26 which engages one of the springs of a normally open pair of electrical contact springs I27. When electromagnet H2 becomes energized and moves lever H6 into its operated position the lever closes electrical contact springs I21 and they remain closed as long as electromagnet H2 remains energized. One of the electrical contact springs I2? is connected by con-- ductor I29 to one spring of each of the pairs of electrical contact springs I9 and the other spring of the contacts I21 and of each of the contacts I9 has electrical circuit connections which will be described later.

The selectable function levers 56 and 51 are provided with forwardly extending arms 9'I and I 36 respectively, the former of which is arranged to close normally open contacts IUI and the latter of which is arranged to open normally closed contact I02. The contacts IUI have no utility in connection with the switching system shown in Fig. 6 but both sets of contacts IOI and I02 have utility in connection with the switching system shown in Figs. 7' and 8. Additional contacts which cooperate in the control of the switching system are indicated by the reference numeral B33. These contacts are normally open and are arranged to be closed by a pin I34 carried by push bar 84. Preferably the pin I34 is positioned on push bar 84 to close the contacts I33 shortly before push bar 84 reaches the limit of its operating stroke and after it has closed those of the contacts 79 which correspond to selector vanes 24 in marking position. The circuit controlled by the contacts I33 and the reason for this timing of the operation of the contacts I33re1ative to the operation of contacts I9 will be described later.

Referring now to the communication system which is exemplified by Figs. 1 and 6 arranged as shown in Fig. 9, the reference numeral 20I designates a line circuit which extends to the station shown in Figs. 1 and '6 from a remote point at which there may be located in association with the communication line 20I printing telegraph apparatus including a transmitter and a receiving recorder. At the station shown in Figs. 1 and 6 the line circuit 20I includes the operating windings of biased repeater relays 262, 203, 206, 261 and 268, and the transmitting contacts of the transmitter device I4'I (Fig. 1) which may be of the keyboard controlled species intimately associated with the combined recording and switching device shown in Fig. 1 or may be a machine transmitter such as one controlled by perforated tape.

The repeater relays 266, 201, and 268 are representative of a class of relays for controlling remote printing telegraph receiving devices and it will be-understood that there may be as many more of these relays to control additional remote stations as the code under the control of which the switching mechanism is operated will accommodate.

The relays 202 and 203 are so biased as to be always responsive to signals on the communication line 20I. 'The armature of relay 202 is connected to ground and the marking contact, which the armature engages when marking current is present on the communication line 20I, is connected to conductor 25!] which extends to and connects with conductor I50 of Fig. 1 and conductor I56 is connected to' one terminal of the selector magnet "II (Fig. 1) the other terminal of which is connectedto grounded battery I42. The selector magnet I I is the signal responsive device which controls the selector mechanism of the combinedrecording and switching instrumentality'previously described with particular reference to Fig. 2. Since relay 202 is always biased to respond to signals on the communication line, the selector magnet I I follows all such signals.

'The'armature of repeater relay 263 is connected to ground and the marking contact of that relay is connected through resistor 2 to the positive terminal of grounded battery 2i?., and is also connected through grid resistor 2I3 to the grid of an electron discharge tube 2 I4. The electron discharge tube '2I4 is a delayed action device by virtue of having condenser 2I6 connected between its grid resistor and its cathode. When the armature of repeater relay 23 is on its marking contact, condenser 2I6 and the grid of discharge tube 2I4 are grounded and no current will fiow in the plate circuit of the discharge tube. When the armature of relay 263 leaves its marking contact, condenser 2I6 begins to charge by current 'from battery 2I2 flowing through resistor 2| I. Resistor 2l I and condenser 2I6 are of such values that condenser 2I6 will not become charged sufficiently toraise the potential of the grid of discharge tube 214 to that positive potential at which tube 2I4 will be rendered conductive until the armature of relay 203 has remained away from its marking contact continuously for an interval exceeding the longest spacing interval involved in ordinary transmission of telegraph signals. When relay 263 is responding to ordinary telegraph signals the armature will oscillate between marking and spacing positions but the potential of the grid of discharge tube 2 I4 will not be raised sufiiciently during any interval that the armature of the relay is off its marking contact to render the tube conductive. However, when a long spacing interval is impressed upon communication line 21, tube 2I.4 will be rendered conductive and relay -2I'1 including in its plate circuit will 'be operated.

Upon the operation of relay 2I-1 its single grounded armature engages its front contact to complete the energizing circuit for a relay 2" through conductor 2| 9, winding of re1ay2l8 to grounded battery 22I. Relay J2I8 completes a holding circuit for itself from battery 22I, windarmature and front contact, conductor 252 extending to and connecting with conductor I52 01' Fig. 1 and through conductor I52 and the winding .of print suppressing magnet II2 to grounded battery II3, whereby the magnet becomes energized and attracts its upperand lower armatures. As previously described, the magnet II3 conditions push bar 84 to be operated by function bail blade 9i, blocks the print bail blade 39 to suppress printing, and closes the normally open contacts I21. The outer right-hand armature of relay 2 I 8 extends a ground connection through its front contact, through conductor 253 which extends to and connects with conductor I53 in Fig. 1 to the upper spring of contacts I21, and these contacts now being closed, the ground connection is extended over conductor I29 to one contact of each of the pairs of contact springs 19 and to the right-hand spring of the normally open contacts I33.

The other spring of each of the five pairs of contacts 19, is connected to one of five conductors I54 which extend to and connect with five conductors 254 in Fig. 2 which extend to five relays 226, 221, 228, 229, and 236, each of which has connection to grounded battery. The relays 226, 221, 228, 229, and 230 control a fan circuit system involving progressively doubling sets of armatures and contacts. Thus the relay 226 has one armature operable between a back and a front contact. Relay 221 has two armatures operable between two front and two back contact, the armatures being connected to the back and front contacts of relay 226. Relay 228 has four armatures connected to the two front contacts and two back contacts of relay 221 and eight contacts which may be connected to a maximum of eight armatures of relay 229. Relay 229 has a maximum of sixteen contacts some or all of which are connected to a maximum of sixteen armatures of relay 230 which cooperate with thirty-two contacts, sixteen of which are front contacts and the remaining sixteen are back contacts. With this arrangement any one of a maximum of thirty-two conductive paths may be completed from the armature of relay 226 to one of the thirty-two contacts of the relay 236 by the selective energization of the relays 226 to 230 in permutational combination.

From certain of the contacts of'relay 28!! conductors 23I, 232, and 233 extend to the windings of relays 236, 231, and 238, respectively, each of which is connected to a grounded battery. From the left-hand spring of contact I33 (Fig. 1) a conductor I55 extends to and connects with conductor 255 of Fig. 6 which is connected to the single armature of the first relay 226 in the fan circuit system. a

Following the energlzation and locking of relay 2I8 as previously described and the resulting operation of electromagnet H2 the system is: in condition to receive signals for. performing switching operations, the operation of the printing bail having been suppressed. Relay 203 will follow the switching control signals and upon first reengagement of the armature of relay 203 with its marking contact, condenser 2I6 will be discharged, discharge tube 2I4 will be restored to non-conductive condition .and relay 2I1 will be released. This will have no effect upon relay 2 I8 since that relay is now maintained energized through its holding circuit. Relay 202 will also follow the switching control signals and will cause the operation of selector magnet, II to effeet the setting of the selector vanes 24 incorrespondence with the, received signal. Following the setting of the selector vanes 24 function bail 6I will be operated and since push bar 84 has been brought into cooperation with the function bail blade 9| the push bar will be reciprocated to effect the closure of those of the contacts 19 which correspond to selector vanes now in marking position and upon the closure of certain ones of the contacts 19 their associated ones of the relays 226 to 230 will be energized over thepath from ground at the outer right-hand armature of relay 2I8 through the outer right-hand front contact, conductor 233, conductor I53, contacts I21 now closed, conductor I29, those of the contacts 19 that are closed, corresponding ones of the conductors I54 and 254 to correspondingones of the relays 226 to 230.. After the closure of contacts 19 and energization of certain ones of the fan circuit relays, and specifically near the end of the operating stroke of push bar 86, contacts I33 are closed by pin I34 to complete a conductive path following the one just described down to the contacts 19 but continuing over the conductor I29, closedcontacts I33, conductor I55,

conductor 255, and through the fan circuit path previously completed by the relays 226 to 230 through one of the conductors 231, 232, or 233 and thence to one of the relays 236, 231 or 238, which becomes energized. It will be understood that the three relays 236, 231, and 238 and their associated conductors 23I, 232, and 233 have been shown merely by way of exemplifying the invention and that there may be as many as thirtyone such relays connected by conductors to thirty-one of the contacts of relay 230, it being preferable not to use the extreme left-hand back contact of relay 230 since a path is complete from the armature of relay 226 to this contact of the relay 230 when the fan circuit system is in the idle condition whereby a selective switching operation might be performed in response to the all-spacing signal and also in response to the long spacing signal by which electron discharge tube 2I4 is rendered conductive to initiate the operation of the switching mechanism.

Upon the energization of any one of the relays 236, 231, or 236a holding circuittherefor is established from grounded battery through the winding .of the relay, inner upper armature and front contact, conductor 24I, back contact and armature of relay 242 to ground.

For the purpose of completing the description upper outer armature of relay 236 is connected ,byconductor- 243 to on terminal of the. biasing winding of repeater relay 206 the other terminal .ofzwhich isconnected to, ground. The back and front conta'ctswith which the outerupp'erzarmature, of relay 236 cooperate, are connected to battery of opposite polarities, The battery connected to the back contact is of such polarity as to render the relay 206 unresponsive to sig.,- nals on the communication line 20I- .However, when relay- 236 is energized .the battery connected to the front contact and therefore to the biasing winding of relay 206 1 biases the relay oppositely and renders it responsive, to. signals on the communication line. v

The armature of relay 206 is connected to one end of a telegraph line 244 extending to arernote station 246. The remote station 246 has been indicated symbolically by selector magnet 241 of a receiving printer or other recorder. Telegraph line 244 has been indicated for polar operation by virtue of the connection of battery of opposite polarity to'the marking and spacing contacts of repeater relay 206. It will be understood thatif it is desired to operate the telegraph line 244 and the station 246 according to a neutral system, this may be accomplished byconnecting the marking contact of. relay. 206 to battery and by connecting the spacing con:- tact to ground instead of to a battery of opposite polarity. With relay 236 energized repeater relay 206 will oscillate its armature between the marking and spacing contacts and repeat telegraph signals received over line 20I from the transmitter I4.I or, from-a remote transmitter to the telegraph line 244 and such repeated signals will be received at the station 246.

The lower armature of relay 236 is connected to ground and when none of l th relays 236,231

and. 238 is energized a circuit is completed from relays 231 or 238 is energized, the series circuit through their lower armatures and back contacts from the ground on the lower armature of .relay 236 to the winding of relay 249 is interrupted so that the relay. 243 becomes deenergized and after an interval releases its armature. The lower-front contact of'each of the relays 236, 231, and 238 is connected to conductor'262 which extends to the front contact of relay .249 the armature of which is connected to one terminal of relay 223, the other terminal of which is connected to grounded battery 263. Thus the relay 236 when energized transfers the ground at its lower armature from the energizing circuit for the relay 249 to the energizing circuit for the relay 223 which becomes energized through the armature and front contactof relay 249 in the interval between the interruption of the energizing circuit for relay 249 and the release of the armature of that relay. In'this way the holding circuit for the relay 2I8 is'in- 'ter-rupted and the relay isreleased incident to a switching operation. The relay 2I8-1 upoh being released opens the energizing circuit for electromagnet II2 whereby the suppression of printing is terminated and the push .bar 84 is restored to disabled condition. r f

At the conclusion of the transmission of message material intended for theremote' station 246, relay 236 having remainedenergize'd during the vtransmission of message. material to that 2,1W5,'i'QAIe' additional. relays may: be interlockedtwith. the

relays 236, 231, and; 2382111 the-same manner.

Referring;- now to theembodimentof the in vention which. is shown in Figs. 1, '7 and 8 when arranged as shown. in Fig.v 10, and particularly to Fig,v 8, the reference numeral 3m designates the receiving. line andSM designates the trans mitting, line of a telegraph communicationchannel which is. sometimes designated as. a full duplex system byvirtue of the fact that simul--- taneous two-way transmission of telegraph signals may be accomplished. At a pointwhere switching operations are-.to'be performed the communication line. 301 extends through a repeater. station. 303 which has. a. repeater relay 3M for. controlling the switching instrumentality and one: or more: relays. for controlling individual telegraph. linesextending'to other printing telegraph stations... As will beiherein'afterr described theefiectiveness" of. the repeater relay or: relays- 30.6 is. controlled by; the. switching; instrumentality'. The operating windings of. allot the-re repeater station 303 andhaving. a. repeater relay 3-08 for" controlling: another: switching instrumentality and: one-or: more relays; 389': for controllingtelegrapht lines. extending to other printing telegraphstationsz,

Therrepeaterirelay 304 has. its biasing: winding:

cormectedi toibattery' o'ffsuch' polarity that the: relay always; follows telegraph signals received over telegraphlinerw I. and the: grounded: arma-- ture: of relay 304 the: idle condition: engages the! left-handor'marking contact" of: the relay to which is connected conductor: 350*WhiCh' ex;-- tend's' to" and connects: with conductor I50. of Fig". 1-. and. conductor" I-l1iis" connected? to; one terminalof." the: winding of J selector magnet II the other terminal of which is connected to grounded'rbattery I42.

The;v switching? mechanism controlled; by" the contacts: 'I9i'of"Fig;. 1 is shown: in Fig.7 in...the normalionidle: condition and: in such: condition anenergizing circuit for: the print suppression magnet M2".- may be tracedf from the. grounded lowenarmatureeof relay 3H through: theback contact. oi the relay; conductor 3J2; conductor 352 which: extends to and connects with conductor I52 of Fig; 1',.through conductor I52,

winding of electromagnet II 2; to grounded bat-' tery H31 Through this: circuit. electromagnet I I2 isi'normally energized: and itsv attracted lower armature? lever il'll holds-detent'v pin 92 outtof' engagementwith push bar"84: so: that the push bar is: conditioned tooperate';v Its: upper armature I I4 holds lever I I 91in. blocking: relation to print bail operating blade 39 and holds contacts. I21 closed; The contacts r I 21 prepare a circuit which will be: subsequently extended" through the switching contacts 19, the circuit'extending from ground i at: the lower armature of a relay 3-I3 through? the lower back contact of that relay, conductor 3 I 4, lower armature and back contact of relay'slt; conductor" 353' extending to and connecting: with conductor Ifis ot Fig. 1 closed contacts lz r'andconductor H283 to one contact spring: of each of the five sets of 'contacts T9 andralso to the right-hand spring of the contacts-I33z The other spring of each ofthe five sets of contacts: 19 is connected t oneof five. conductors I54which extendtoand connect with five conductors354 which extend to five relays 3", 31 8, 319, 320 and 32I, each of which has connection to grounded battery. As in the previously described embodiment of the invention the relays 311. to 321, inclusive, .control av-fan circuit. system involvingprogressively doublingv sets ofarmaturesand contacts. The single armature of relay 3II which is at the apex ofthefan circuit isconnectedtoconductor 355=which extends to and. connects-with conductor. I55 of Fig- 1-.which in turnextendslto. the left-hand spring of the contacts.- I33 thatare ;operated by push. bar. 84 near the.-end.of itsstroke aftenithas closedl those of the setscot. contacts. 19, the. bell. cranks ..'I.I of. whichfindsselector vanesid invmarkingposition.

As an introduction. tonthe operation .ofthesysswitching instrumentality shownin.Eig;,1.-for re.-- cording a message.-- The; appropriate. code signal.

combination will be impressed. upon .theltelegraph.

line 301' at some remoteipoint. and will-bereceived by theselector. magnet. H to. cause the positioning of the selectorvanesin permutationalpositions corresponding.tothereceivedsige nal. Followingthesettinggof theiselector. vanes, push bar' 84 will be-operated by function bail. blade: BI to close. correSponding .-0nes. ottheccom tactsv 19 whereby corresponding ones of the. relays 311 to 32 I, inclusive,.wil1. be. energizedithrough. the circuit from. ground atthe lower armature and back contact ofarelay 3-H and. through the closed contacts t2 and certain ones of. the. contacts 19 Thereafterv contacts: I33 will be-closed to establish ground. connection. from the. same ground; to thesinglearmature of relay 3.I.I'a-nd thus through the fan circuit path-prepared bythe energized one-0t the relays 3L1 to.=32l, inclusive. Thereason /forproviding :for the closure. of contacts I 33 after. thecontacts 79 have. been. closed is toi-permitrthe fancircuit relays3-l1 to=32.I, inelusive, or in the case of the system shownin Fig. 6, the relays- 22! "00.239, inclusive, to become. operatedbefore a conductive. path is established through the fan circuit .ar-matures and. .contacts in order that no false pathshallbeestablished. momentarily while the fan circuit controlling. relaysare. attracting their" armatures, since :the re.- lays may not all attracttheir armatures at exactlythe same time.

In. response. to. the signal-tor causing the. com, bined. printing and. switchin instrumentality. to be-placedin printing condition, alpatlris. estabs lishedthrough-the fan circuitfor the energize.- tion of arelay-322 -from:ground extendedthrough contacts I21; momentarily closed contacts- I33, armatures and contacts of the fan circuit through the extremezright-hand front-contact of relay MI and thence. over-conductor32'3, upper= most armature and back contact: of relay- 31 I,

and; windingof' relay 322" to groundedbattery. A holding: circuitfor relay 322 is established from the grounded-battery through its-swinding, its armature andfront contact; conductor 324; winding of relay'326, conductor- 35 which extends to and connects with conductor I5-I- of Fig. 1-, and over conductor I SI and normally 'closed' contacts I92 to'groun'd'. Relay 326 becomes energized over the holding path just described and establishes an energizing circuit for relay 3-11 from the grounded armature and'front contact of relay 326; through the winding ofrelay 31 I, to grounded battery. Upon the operation of relay 3,

which remainsenergized as long as relays 322' and 326 remain energized, ground at its lower armature is disconnected from conductor 352 and thereby from the winding of electromagnet II2 which releases its armatures to disable the mechanism for operating switching contacts I9 and to terminate the detention of printing bail operating blade 39. Thereafter as long as relay 322 remains energized the combined recording and switching instrumentality will operate as a telegraph signal receiving printer but not as a switching device, responding to signals on the telegraph 30I and printing message material corresponding to signals received. It will 'be noted that the relay 3II at its uppermost armature transfers conductor 323 from the energizing circuit for relay 322 to conductor 321 which extends through the winding of a relay 328 to grounded battery. This apparent preparation of an energizing circuit for the relay 328 has no utility at this time because the switching control contacts 19 are disabled and an energizing circuit for the relay 328 cannot be completed through the fan circuit system.

When the transmission of message material to the combined recording and switching instrumentality has been concluded and it is desired to restore that instrumentality to normal condition this may be accomplished by the transmission of the code combination to which the selectable function lever 51 is responsive. The function lever will respond by momentarily opening the contact I02 thereby interrupting the holding circuit for relay 322 which extends through relay 326. Both relays will be released and relay 326 removes ground from the energizing circuit for relay 3 which also releases, reestablishing the path over conductor 323 to the winding of relay 322 and at the lower armature and back contact of relay 3II restoring the ground connection for energizing print suppression magnet H2 over conductors 352 and I52. The combined recording and switching instrumentality is thus restored to condition for performing switching operations and for the suppression of printing.

Assume now that it is desired to place the combined recordin and switching instrumentality of Fig. 1 in condition in which it will neither print nor perform switching operations. This is accomplished by the transmission over telegraph line I from a remote point of the code combination which will cause the contacts I9 to operate to establish a conductive path from ground through the fan circuit system and through the second armature of relay 32I counting from the right, and its front contact, conductor 329, innermost upper armature and back contact of relay 3I I, conductor 33!, and winding of relay 3I6 to grounded battery. Relay 3I6 establishes its own holding circuit from the grounded battery through the winding of the relay, upper armature and front contact to conductor 324, and thence through the winding of relay 326 to ground at the normally closed contacts I02 as previously traced. This results in the energization of relay 326 which completes the energizing circuit for relay 3II thereby removing the ground connection to conductor 352 at the lower armature and back contact of that relay. However, a substitute ground connection for the conductor 352 is completed from the grounded lower armature and back contact of relay 3I3, through conductor 3I4, lower armature and front contact of relay 3 I 6 and conductor 332 to conductor 352 and thus to the winding of electromagnet II2 to hold that magnet energized to suppress printing. The substitute ground connection for the conductor 352 is" transferred by relay 3I6 from conductor 353 over which the ground connection had previously been supplied through conductor I53 and closed contacts I21. From this it will be apparent that although electromagnet II2 remains energized and causes contacts I9 to be operated in permutational combinations in response to each signal thereafter received, no switching operations will be performed because the energizing circuit for the relays 3I1 to 32I, inclusive, and the circuit to the apex armature of the fan circuit system remains open at the lower back contact of relay 3 I 6. It will be noted that upon the operation of relay 3 the conductor 329 is transferred at the innermost upper armature and front contact of the relay to conductor 321 which extends to the winding of relay 328. By this transfer an apparent circuit for the energization of relay 328' is prepared but such circuit cannot be completed over the conductor 329 at this time because ground connection for the switching control relays 3H to 32I and for fan circuit paths has been removed at the lower armature and back contact of relay 3 I 6.

The restoration of the combined recording and switching instrumentality to switching condition is accomplished in the same manner as hereinbe-' fore outlined, namely, by the signal responsive selection of function lever 51 which causes contacts I02 to be opened momentarily. These con-: tacts interrupt the holding circuit for the relay 3I6 and both relays 3I6 and 326 release. The relay 326 releases 3II which restores the ground connection through its lower armature for continuing the suppression of printing and the relay 3I6 removes the substitute ground from the circuit of the magnet H2 and restores that ground to the conductor 353 thus reconditioning the fan circuit to be effective.

Another and primary function of the switching mechanism is to render a remote receiving printer responsive to telegraph signals on the telegraph line 30L This is accomplished by the energize.- tion'of the relay 3I3 over the fan circuit system from the right-hand back contact of relay 32I, conductor 333, intermediate upper armature and back contact of relay 3II, conductor 334, and winding of relay 3I3 to grounded battery. The relay 3I3 completes its own holding circuit from the grounded battery through the winding of the relay, inner upper armature and front contact, conductor 324, winding of relay 326, conductor 35I and thence over conductor I5I to ground at the normally closed contacts I02. Again the relay 326 completes the energizing circuit for relay 3I I which removes ground at its lower back contact from conductor 352. However, the relay 3I3 transfers a substitute ground to the conductor 352 at its grounded lower armature and front contact so that electromagnet II2 remains energized to suppress printing.

It will be noted that by virtue of the transfer of the ground connection on the lower armature of relay 3I3 from the back contact to the front contact, ground is removed from conductor 35!. which is the feeder circuit to contacts I9 and I33, so that although electromagnet I I2 remains energized while relay 3I3 is energized and. contacts I! are operated in permutational combinations responsive to signals thereafter received, the switching relays 3I'I to 32I are not operated and no conductive path through the fan circuit system is completed. Upon the operation of relay 3| I its upper middle armature transfers conductor 333 from conductor: 334% to: conductor: 32:1 winch; em tendsatocthe windingcoftrelam 328: Re1ay 328icannotrbecome energized over:v this:circuit;duringithe receptiomoff signals: thereafter receivedi for; the? reasonthatirelay 3133has operated torpreventtthe;

energization of anwofrtherelays 3:11 to: 321, in:- elusive, or the: completion of 8L conductive path through the fan' circuit-system;

It will ':be.- noted that the back: contact f'or- -the upper outer armature of relay 3l3 is connected" to positive. batteryand that the armature is: connected: by: conductor 336 to one e-ndt'of the-biasing.v winding of repeater relay: 306 the: other end of:

which: is connected? to ground. The batteryconnectiomwhich is appli'ed to the biasing winding: of'relay 306 when relay 3 I36 is deenergized-is: such as: to bias relay 30 fi against-response" to telegraph signals traversing the telegraph line; 30 I and ac:-

cordingl'y the armature ofirel'ay 306 willnot'o's cill'ate'- between its marking and spacing: contacts is connected to negative battery. Thus when rel'ay Mil-becomes energizedthe-polarity oflthe biasingpotential applied to relay 30B isreversed and this-'renders the relay; 306 responsive t'o -si'gnalson telegraph line 331'- so-that' the armature-oscillates between: marking and spacing contacts which are connected-to batteries of opposite polarities; The 1 armature of relay- 306-15 connected to a telegraph line 3'39' which extendsto a remote station 341 and at" the station 3'M'the telegraph-1ine'339' isconnected to the operating-'winding-of' a, receivingline relay 342 Relay3'42-hasa biasing winding whichis biasedby-the proper polarity of battery-toner; mit: the armatureof relay 342 to oscillate-in response to telegraph signals impressed upon te'l'e; graph line 339 by relay 306 and the marking-com tact with which the armature of relay 342 ccoperates is connected to grounded-battery; Thearmature of relay 342- is connected to one termimail of the-winding' of'a selector magnet343 which represents symbolicallya receiving" telegraph printer; When relay-313 conditions the relay3llfi to respond" to: telegraph signals; such; s'ignal's will berepeated'to telegraph line 339, will be received byline relay- 342 and will' operatesel'ector mag; net-343 tocause the receiving printer represented by the selectorsmagnet to' record message mater ial transmitted over telegraphline 30; During the timethat signals are being"received by-theline relay 342 'the combined recording and switching instrumentality of Fig. 1 will be neither print'ing nor performing switchingoperations' in response to such signalsdue to the factthat' relay 3|3 is operated.

The channelling of telegraph signals to the staticn34 l may be terminated-'by the same: means asthat employed for "terminating: signal'frespon sive printing operation on for: terminating total disahlementrof the combined; recording: and switching instrumentality of Elgi. 1,: namelmbyr the signak responsive operationfof' selectable'rfiinc ti'orn lever 51 which: will-open the-normally closed contacts lib-2:. thus; releasing." relays 3413, 326: and: 31 I gunestoring; the.- disab'li'ng 'bias: to; repeater:301i; restoring-theground at the lower: back contact of relay 3 I 1 to; the-circuit1 3:52. of 7 print -;suppressio1r magnet; H2 and, transferring; the substitute groundifmmaconductomaflrtmtheefeedemconduc- 2112353? for thesswitching-r.relayscfifl itor attains clusiyaamiifor thefamcircuitipathi Itzwilk bemnderstoowthat fitris withimthezcom templatiorr of: the '1 present: embodiments: oil the;

invention; to: provide: additional? relays; similar? tmthearelay 1313 anwzoperable through additionalarn-raturest ands contacts of :t the: relay 3;: from others-ref? the:- baclc or" front-.contactsaofi the; final switching relay;32:l r. for 1 controlling: other: repeateirrgz relayszzcorrespondingztu thetrelay 306.! forrree peating telegraph signalsztraversingtelegraph liner 301M302 other" telegraphfllines: corresponding to the:

line 3 392 extending-ate other-remote; telegraph stat+ 7 tionsz. ItswzilLalso be understoodfthat itfi's within; the contemplation; otzthe present embodiment off this inventionzto providerforrtheselectiveidisables1 ment of the print suppressionzmechanism: offtlie? combined? recording and switching". instrumentality shown-11111 18. 1; incconnection with 'the seleca tive operation-- ofi'thev relay 3131' or any additionali relay: of' its class for the purposeof causing; the

combined printing:-and switching:instrumentality to. monitor or printzforotheriuseful purpose mes-- sage: materialcorresponding- 'tow'signals repeated: law-remote! stations by repeater relay- 306 ortother relaysaof that class-,: such monitoring! having been described? in connection. with the embodiment: of theuinventionv. shown inthe. combinatiomof The present embodiment of the. inventionza lso contemplatestthe controlglby the switchingmecm anism; of "transmitters-- for impressing:v telegraph signals: upon the sending: line 302: Accordingly;

. thatelegraphline- 302 hasi inseriestherewithikey board; controlled 1 transmitting" contacts I41 T (Fig. 13 the transmitting contacts: and distributor: rings; oi a perforated tape controlledi=' machine: tI amISmitter '34 I0Ba1- to the combined recording; and switching instrumentality of Fig; 1; but

' shown in Fig: 89 similar keyboard? controlled Fin iii)

transmitting: contacts 346 and perforatedi 'tape controlled machine transmitter attheremote statihn' 341, and keyboard: and-' tape" controlledi transmitter: at= as many other-remote stations: as may be desired up-to=tlie*limit ofthe selective switching. possibilities afforded by the code-upon whichithe system is operable. The keyb'oard'con trollc'di transmitters: MI and 346'? are f ully' clis v cl'csed in the" previously. identified patent to Mortomet a1 1- and bein manua'lly; operable there is i notoc'casion fomsabieeting them. to control by theszswitchihg: mechanismzi The-tape controlled transmittenmaybecf the typei'disclosed iinsPatent- 2.9551565? granted September-v29; 1936, to: E; F." lllratson and the disclosure: of: this: patent :is incorporated herein by: reference: ass part: of; the present; specificationw At. each. of; the stations which: issprovidedf with a tape controlled transmitter: theta iss a' tape perforator 34Bliwhichi may be similar to that shown in Patent 11,182,179;

Referring now to'Fig. lapair 'of normally open contacts |6| is operable momentarily by the selectable function lever 56 when the selector-vanes 24 have been set 'underxthe control of a received signal for the selection of the lever 56; One of the contacts ||J| is connected to ground and the other is connected to conductor I56 which extends to and-connects with conductor 356 of Fig.

7 which extends a conductive path'through conductor 349 to one terminal of relay 338, the other terminal of which is connected to grounded battery. Upon being energized the relay 338 establishes its own holding circuit from grounded battery1 through the winding of the relay, conductor 349, contacts operable in make-beforebreak manner by the armature of relay 328, conductor136|, front contact and armature of relay 338 to ground;

Relay'338 performs'a number of functions; At armature it reverses the polarity of battery applied to the outer upper front contact ofrelay 3| 3 so that if the relay 3 I 3 is then energized to'qualify repeater relay 306 to repeat signals'to the telegraph line 339'the relay 306 will be disabled and prevented from following or repeating to line 339 signals received'over telegraph line 30| immediately following the energization of relay 338,- since such signals pertain to switching operation involving transmitters, as ,will presently appear, and might cause the printing of erroneous characters if permitted to be repeated to the telegraph line 339.. The armatures 2 and 3 of relay 338 are connected-to ground and their front con tacts are connected to the conductors 353 and 352,

respectively, for the purpose of supplying ground to energize electromagnet M2 to suppress printing if that magnet has not been energized, and

for the purpose of supplying ground to the feeder conductor 353 for the switching relays 3|1 to 32|, inclusive, and for the fan circuit system. 'Armature 4-is also connected to ground and its front contact is connected to the winding of relay 3| I, so that if that relay is not at this time energized it will become energized and by means of itsupper armatures will interrupt the conductive paths from fan circuit conductors 3'23, 329 and 333 to the relays 322, 3|6 and 3|3, respectively, and will connect those paths to conductor 321, as previously set forth. Each of the lower armatures of relay 338 is connected to a fan circuit conductor extending from one of the contacts of the final switching relay 32|. Armature 9 is connected to fan circuit conductor 362 and its front contact is connected to conductor 321 which extends to the relay 328. Armatures 8 and 1 are connected to fan circuit conductors 363 and 364 and their front contacts are connected to the operating windings of transmitter controlling relays 366 and 361, respectively, the circuits through such windings being completed to grounded battery. Armature 6 of'relay 338 is connected to fan circuit conductor 368 and its front contact is connected to one end of the winding of relay 369, the'other end of which is connected to grounded battery.

. The condition of the apparatus which exists on "the armature 3 of relay 338 and ground forfeeding the fan circuit controlling relays 3| 1 to 32|, inclusive, and for establishing a conductive path through the fan circuit system is supplied at thearmature 2 and front contact of relay 336. A relay 3 is also energized at this time, this relay being normally in energized condition from ground at the lower armature of relay 361 through the lower back contact of that relay, lower armature and back contact of relay 366 through the winding of relay 31| to grounded battery.

The system is now conditioned'to perform a switching operation for controlling a transmit-m ter. It will be assumed that-the signal received isthat which will complete a circuit over the fan circuit conductor 364 whereby the relay 361 will be energized. This relay establishes a holding circuit from grounded battery through the upper or holdingwinding, upper armature and front contact, conductor 312, inner lower arma-- ture and back contact of relay 369, conductor 313 extending into Fig. 8, winding of relay 314 and tape-out contacts 316 to ground, these contacts being closed if there is tape in the transmitter 344 awaiting transmission. The relay 314 completes a circuitfrom ground through the slack tape contacts 311 of transmitter 344 which will be closed if there is 'a loop of perforated tape between perforator 348 and transmitter 344 awaiting transmission, armature and front contact of relay 314, switch 318 which will presumably be closed manually as one of the operations incident to starting up the system on each business day, and winding of transmitter start magnet 319 to grounded battery. Thus the start magnet 319 will be operated to release the transmitting distributor shaft for rotation and the shaft will rotate continuously to effect the transmission of signals stored in the tape until the slack in the tape between perforator 348 and transmitter 344 has been taken up, at which time the slack tape contacts 311 will be opened-to interrupt the energizing circuit for the start magnet 319 which becomes deenergized and stops the-transmitter shaft.

If the tape, instead of being left connected to I tape-out contacts to open. Under these circum'-- stances the holding circuit for relay 361, which includes the winding of relay 314, will be interrupted and both relays will be released, the relay 314 interrupting the circuit for the start magnet 319, which releases to arrest the transmitting distributor shaft.

At the time that relay 361 operated and completed its holding ciircuit through relay 314, it also transferred the ground connection on its lower armature from the lower back contact to the lower front contact. This interrupts the energizing circuit for relay 31i which is a slowrelease relay, and completes'an energizing circuit for the relay 328 from the grounded lower armature and front contact of relay 361, conductor 36| front contact and armature of slowrelease relay 3H and winding of relay 328 to grounded battery. Relay 328 thus becomes enerized before the relay 31| releases its armature and first establishes a'hold'ing circuit through its armature, make-before-break contact con trolled by the armature, conductor 36|, front .contactand-iarmature'.5-;of=relay ,338;.to 1gre1mdc roundiat the tap eoli ont cts 384. T an Thereafter: the armature ofrelay 328 :Ibreaks the holding circuit for relay .338 which releases-Mall .of tits armatures and in so doing releases the holding circuit forrelay 328 which releases, its

:armature to again prepare the :holding v circuit path .for relay 338 through the make-before- ,break front contact of rela v328. ,{Ifhe releasing time forrelay 3.11 is such that thatrelayqhas released its armature before the holding circuit .for the relay328 isinterruptemso that .the relay 338 shall not be reenergized from ground,sup-

-plied over the conductor 38! att-he instantthat the movable front contact ,of;.relay.,328-.has:reclosed to the stationary contact-and-the armature :of relay 328 hasnot moved :outof :engage- -.:ment withthe movablefront contact.

to negative polarity torecondition-the relayBfiB to respond to signals on ,the telegraph line- 301 vz-if the relay 313, is at this time energized.

.The operation of the tape transmitter 344 may be terminated under ,the control of' the switching mechanism by .the si nal respons ve N operation of the contacts IIJI wto efiectreenergization of the relay 338, followed by the operation of the fan circuit system in-responsetothe proper :signal to complete a conductive ,'path through the fan circuit conductor 368 .tocth winding of relay 369 which isconnected to grounded battery. The relay 3-69, wilLattractall of its .armatures'and interruptat theinner, lower :armature theholding cireuitforthe ,relay361,

which includes the'conductor 313 and the winding of relay 314 associated .with tape, transmitter .344. Even though the holding circuit for the relayv 361 had been interrupted automatically ,by

. operation-of the tape-out contact 316 this might -,not have become ,known at thetransrnittinefitaetion from which signals for controlling the switching instrumentality are transmitted and,

vaccordingly, it wouldprobably be astandard operating routine to stop the tape transmitter344 under signal control after areasonable tim for thetransmission of message material had elapsed or in anyevent it would be necessary to stop the transmitter in order to permit another station to transmit message .materialto the transmitting ,line- 302. ,Upon the release of relay 361 its lower I ;,armature reestablishes the energizing circuit "for relay 311 but it also removes ground, connection from conductor38l so that. relay 328,,does not become energized automatically ,andthe holding circuit forrelay333 ismaintained. The apparatus is thus placed in conditionvfor starting another tape transmitter, which may be accomplished by the signal responsive operation of the fan circuit system to complete the energizing circuit for another transmitter controllingrelay.

such as the relay 366. This relay establishes a holding circuit similar to that of relay @361 through the lowerouter armature and back con- ,tact .orrelay 369 conductor 382 extendingtinto Eig. 8, winding of relay 383- at1 station 34l 3'60,

'mitter .341,.-has slack man conta ts 8 an a transmitter sta ma net 381 similar t c -r spondin e1ements..;o trans t e -th transmitterfifl will he s arted lithe t pe-out contacts.38 andsl ck tap mnt v re-bo closed. At its lower armature thev el yfififi trans .iers the ground -.co,nnect 0n1-supp1ied fro th .-.1o.w.er armatu zand1iba k zconta t of vr lay-.3 iiromcrelay v3 to conductor 38 l and thus to the ewindin gsof ruelay 3128 whereby relay 1328 is energized, ,-relay;3 38 is-released and then relay i328 .aisreleasecl.

.If after the ope at on and lo k ng of re1ay.338 and th ope a i n o relay 35, ad bee desiredto Start no other transmitter, the transmitt centro linamec anism w uld h be n res ored to 5 normal, by igna es onsiye operat ono th fan circuite s e to comp ete; a. fan circuit path through : conductor 3,62 and through the armature 9 and front-contact of relay 338 to conductor 321 andthus ito rela y 3l ll. Relay ,32-8 .r,el.eases-,relay 338 which in turn releases reda -1W ;if t-that erel i' was n o e ated at t e .timethatcontacts l0 l-were operated.

. trte-ferenoe is now-. inade to, the. previously .men- ,tioned qfact that all ,of the upper front contacts o the relay-1.3 I here co nect d to vco u torr3 rh che xt nds .to r lay-3 5.5 hatwhen relay 311 i :in th ener ize c ndiliie i ermine i connected through the ian cirouit to any; one o the flQn l-lG I ..:1 g t the runner armature. .of l ys-H lrrela fi fl l ,b ener ized. il was also point dp eviously t wh n th .re yfi H is :ini h en reizedcenditiQn-: n -t .enere ea o eficn .e the-rela th ra itto hic in ludes a up e hack. cont t-r relay 3| thesebeing the re1ays,322,,3l3 an d 31.6, a p h tbrcueht a uitsyste c n -b wirm l ted duet t fact .th t th mechani m efe -ope ating th s tch n c tacts 519 is idl tabled ,or ground connection fior operating the :ia :Q rcuit .cqntrol i l relay to 3 I in l s v .and .for m etin .a con luctire .pa

throu ht e:fanic r uit-zs stemis.rem re :HQ r w en relay 3 ,.become rq e ated th ou sth re q u-re .of contacts l-fll ground for the;fan

circuit controlling ,relays and for the fan circuit sys em. is, appliedtiromztheigrounded a m tu e. 2:,of, rrelay 33fl. ra-that g sponset -.sisnal thereafter received the, switc ing r ays 3l1to 32!, inc us e, w l he oper ed and a ondu tiv -,gua h.th .queh the fan c u teystejrnmay.becom- .uleuad.v ele Dil mma y elay i3 .whether or ;.not it :had, previously been. in energized condition so ;that the ,conductive p,aths extending to the ;upper. armatures gof =re1ay3 I I .are ..exte nded- .-to monductor, 321. It is to .benoted that :contacts NH inyallof the combined recording and switching instrumentalities associated withlin 3 areoeerableinrespen t v the am codetsignal so 7 that, at all switching, stations the relay 3.38.-wi1l;be operated. I

as. ind cated in Fi -{Liall fan circuit paths which are, not assigned .to the cont o of :th switching operation are iextended to l and connested with the conductorjfl whichwhen; relay compl ted-tam re ay. 32, l i he lth oughthecendoctor; 362 or-throug'h pne of the; conductors; 323, .42 ontahsincerelsyd :ieenersiaed-when:relay 338 is energized." The reason for this is that code combinations which are not assigned to control switching operations at the switching station shown in Fig. '7 or which are assigned to operate relays 3l3, 316 or 322 at that station, may be assigned to control the operation of transmitter controlling relays at other switching stations, such as, for example, one which might be controlled by the repeater relay 368 in the repeater at all other switching stations. The circuits prepared through the armatures and front contacts of relay 3, and through armature 9 of relay 338 accomplish this result.

Not only is it possible in accordance with the present invention to assign to the control of one signal combination the operation of a relay for controlling the reception of signals over the communication line 36 l such as one of therelays M3, 3 l 6 or 322, at one station and to control a transmitter starting relay, such as one of the relays 366 or 361 at another station as set forth in the foregoing paragraph, but it is also possible to control a relay in each of the two sets at one station bymeans of'one signal combination. For example, if it is desired that the relay 3l3 which controls the efiectiveness'of repeater relay 366 and the relay 366 which controls the tape transmitter at station 34! shall be alternatively selectable in response to a single code combination, this may be accomplished by the omission of the connection from the upper middle front contact of relay 3| l to conductor 321, which is the reason that this connectionhas been shown dotted, and by connecting conductor 333 to the conductor 363 as indicated" by the dotted line connection 39L With this arrangement-the relay 3l3 can be energized from its fan circuit path only when relay 3 is in deenergized condition, which is the proper-condition for selection of one of the relays 3i3, 3|6 and 322. Whenrelay 338 hasbeen energized under the control of contacts IN, the relay 3 becomes-energized whether or'not it had previously been energized and the common signal for selecting relay 3l3 -or relay 366 will cause a fan circuit path to be completedfor the energization of the relay 366 over the strapping conductor 39l to conductor 363. With conductors 333 and 363 interconnected by the strapping conductor 39| only one conductor from a contact of relay 32! would be employed to complete circuits over the conductors 333 and 363 which is the reason that the conductor from the third back contact of relay 32 I, counting from the right, to conductor 363, has been indicated by a dotted line. It will be apparent that that contact of relay 32| could be assigned to the control of some other switching function.

Although only one relay 3|3 for controlling a remote'telegraph receiver has been shown, it will be understood that there may be many such relays for controlling other remote receiving stations. Similarly, although only two relays 366 and 36'! have been shown for starting tape transmitters, there may be many such relays, and the holding circuits for such relays would be com- -pleted over additional armatures and back con- 'tacts of relay 369, two-unused ones being shownin Fig. 7. The fan circuit system is not shown developed to its full extenteither in Fig. 6 or. Fig.

7, since it will be noted that seven contacts of the relays 229 and 326 have been left unconnected- These contacts would extend. to seven additional armatures of relays 236 and 32| respec-' tively, each of which would have. a front and a back-contact so that a maximum ofthirty-two selective points, namely, the sixteen front and sixteen back contacts of relays 236 and HI :are available to control switchin relays in response to a five-unit code for controllingthe five relays 226 to 236, inclusive, or 3|! to 32 I, inclusive, H

Although two specific embodiments of the invention have been shown in the drawings and described inthe foregoing specification, it isto be understood that the invention is not limited to those specific embodiments but is capable of modification and rearrangement without departing from the spirit of the invention. and. within the scope of the appended claims,

What is claimed is:.

1. In a communication system, a communication channel, means for impressing telegraph signals on said channel, a plurality of telegraph stations associated with said channel, a signal responsive selector mechanism at one of said stations, telegraph message printer mechanism controlled by said selector mechanism, switching mechanism also controlled by said selectormechanism, signal responsive means for disabling said printing mechanism and for conditioning said switching mechanism to be operated, and means controlled by said switching mechanism for qualifying others of said telegraph stations to receive signals impressed on said channel. I

2. In a communication system, a communication channel, means for impressing telegraph signals on said channel, a plurality of telegraph stations associated with said channel, a signal responsive selector mechanism at one of said stations,telegraph message printer mechanism controlled by said selector mechanism, switching mechanism also controlled by said selector mechanism, signal responsive means for disabling said printing mechanism and for conditioning said switching mechanism to be operated, means controlled by said switching mechanism for qualitying others of said telegraph stations to receive signals impressed on said channel, and means controlled by said selector mechanism for restoring said other telegraph stations to non-responsive condition,

3. In a communication system, a communication channel, means for impressing telegraph signals on said channel, a plurality of telegraphstations associated with said channel, a signal responsive selector mechanism at one of said stations, telegraph message printer mechanism controlled by said selector mechanism, switchingmechanism also controlled bysaid selector mechanism,'signal responsive means for disabling said printing mechanism and for conditioning said switching mechanism to be operated, means controlled by said switching mechanism for qualifying others of said telegraph stations to receive signals impressed on said channel, and means controlled by said switching mechanism for restoring said other telegraph stations to. non-responsive condition.

4. In a communication system, a communication channel, means forimpressin telegraph signals on said channel, a plurality oftelegraph stations associated with said channel, a signal-readvance sive means, and means controlled by seeing-rial 'sponsiv selector mechanism "at one of said stations, telegraph message printer mechanism can.

trolled by said selector *mechanism,switchingmechanismalso controlled by said selector mechanism, signal responsive means for 'disabling said printing mechanism and for conditioning said switching mechanism tobe operated, means controlled by said switching mechanism for qualifying others of said telegraph stations to receive signals impressed on said channel, and means controlled by said selector mechanism independently of'said switching mechanism for restoring said othertelegraph stations to non-responsive condition.

5. In a communication system, a communication channel, means for impressing telegraph signals-on-said channel, a plurality of telegraph stations associated with said channel, a signal responsive selector mechanism at one of-said stations,telegraph message printer mechanism controlled by said selector mechanism, switching mechanism also controlled by said selector mechanism, means normally effective to disable said 'printing mechanism and to condition said switching mechanism to be operated, means controlled-bysaid switching mechanism for qualifying others of said telegraph stations to receivesignals'i-mpressed on said'channel and for disabling said switching mechanism, and means controlled by said selector mechanism for restoring said trolled by said selector mechanism'switchin me- -chanism also controlled by said selector mechanism, means normally conditioned to disable said printing mechanism and to condition said switchingmechanism to'be operated, meanscontrolled "by said switching mechanism for qualifying others of said telegraph stations to receive'sig- .nals impressed on said channel, and means controlled by said qualifying means for disabling said switching means and for maintaining said printing means disabled.

- "'7. In a-communication system, .a communication line, means for impressing telegraph-signals on said line, a plurality of signal-repeatingdevices insaid line, a plurality-oftelegraph stations each havingsignal responsivemeans controlled by. one of said signal repeating devices, a telegraphmessage printing mechanism controlled by each of said signal responsive means, meansat one of said stations for suppressing response of the printing mechanism thereat to its signal responsive means, and means controlled by'the-signal responsive means at said one station for controlling the signal responsive operation. of the signal repeating devices in said line other than that bywhich-it iscontrolled.

8. In .a communication system, .a communication line, meansfor impressing telegraph signals on said line, a plurality of signal repeating devices in said line, a plurality of telegraphstations each having signal-responsive means controlled by one of said signal repeatin devices, atelegraph message printing mechanism controlled byyeach of said signal responsive means, means atone of said stations for suppressing response lof uthe printingmebhanism :thereat lto its signalerespon printing mechanism controlled by said selector said"selectormechanism.

responsive means at said one station :onlynzhen said suppressing -means has operated for controlling the signal "responsive operation .:of l the signal repeating devices in said "line other I than that by which it is controlled.

9. In a communication system,,aacommun1cation line, means for impressing telegraph signals on saidline, a plurality of signal repeating devices in said line, a plurality of telegraphsta- 'tions each having signal-responsivemeans :con-

trolled by one of said signal-repeating "devices,

-a telegraph message printing mechanism scontrolled by each of saidsignal responsive means. means at one of said stations for suppressing response of the printing mechanism thereat to its signal responsive means, and means controlled by the signal responsive means atisaid one.:station for selectively rendering responsive or unresponsive to telegraph signals 'the signal repeating devices in said -line other than that which controls the signal responsive :rneans at said :one station. J

10. In a communication system, ascommunioation line, means for impressing marking and spacing Signals-on said line, a-'-te1egraph-station associated with said line having sig-nal responsive means, a selector mechanism controlled :by said signal mesponsive means, .and .a telegraph message printing "mechanism :controlled tbyisaid selector mechanism, means :at said station .for

recognizing spacing signals exceeding a predetermined duration, and means controlled bylsaid recognizing means upon recogmzingrspacingislehale-exceeding apredeterminedduration. for-mendering said printing mechanism .-.unresponsive .:to

1:1. in :arcommunication system, a communication line, -means for impressing :marking iand spacing :signals on said 'iline,-a plurality of .telegraph stations associated .with said line, signal responsive means .at each of saidstations,'=a melegraph message printing mechanism ,controlled zby each of said signal responsive means, switching means at one of said stations :for controllingcthe signal responsive means :at others 40f said rstations, :means at said one station for recognizing spacing .signals exceedingiaepredetermined duration, and means controlled :bysaid recognizin means upon recognizing spacing signals tex- .ceeding a predetermined duration for renderin the printing mechanism unresponsive to. the. si .nal responsive means .-.at said one station; and-for conditioningsaid switchingmeans :to be operated.

12., Inca .communicationsystem, acommunication iline, means ,for impressing markinggend ;spacing. ,signa1s on said 1ine,,:a.telegraphistation associated with said line having .signalresponsive means, a selector mechanism. controlled ;by said signal responsive means, and atelegraph message duration. means controlled by said recognizing means upon recognizing spacing signals'ex'ceeding a predeterminedduration for'rendering the printing mechanism unresponsive to the selector mechanism, andjmeans controlled by said selector mechanism independently or said recognizing means for-restoring said-printing mechanism to responsive condition.

13. In -a communication system, axcommunica-

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