US1537743A - Telegraphy - Google Patents

Description

May 12, 1925. 1,537,743

w. M. BRUCE, JR

TELEGRAPHY Filed April 24, 1920 2 Sheets-Sheet 1 May 12, 1925.

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1,537,743 w. M. BRUCE, JR

TELEGHAPHY Filed April 24, 1920 Ha Z.

2 Sheets-Sheet 2 a 1' ANNE Patented May 12, 1925. I

UNITED STATES WILLIAM M. BRUCE, J'R'., 0F SPRINGFIELD, OHIO.

TELEGRAPHY.

Application filed April 24, 1920. Serial No. 376,353.

To all whom it may concern:

Be it known that I, WILLIAM M. BRUCE, Jr., a citizen of the United States residing at Sprin field, in the county of (llark and State of hi0, have invented certain new and useful Improvements in Telegraphy, of which the following is a specification.

My invention relates to improvements in operating printing devices over submarine cables or conductors of high capacity.

The primary object of my invention is to provide methods and apparatus by which a plurality of messages may be sent in the same direction over a single conductor at the same time.

In carrying out this invention I employ for the most part standard apparatus now already in use in connection with new and improved circuits and apparatus and original methods of operating them.

A primary feature of my invention is the utilization of the usual current impulses of opposite polarity in connection with means for changing the character of certain of these impulses, (preferably in respect to their voltage) and further to provide for a suppression or neutralization of all impulses when certain conditions arise in the operation of a plurality of transmitters at the same time and by the utilization of these different conditions produced by the simultaneous operation of said transmitters (preferably automatic) to operate separate translating' devices at the receiving end of the conductor which will respond to either one or more of the plurality of transmitters sending separate messages at the same time and to cause the said messages to be simultaneously printed on separate printing devices.

Since as above indicated my invention is capable of use with present standard apparatus, I have illustrated the method of carrying out my invention in diagrammatic form in WhlCl'land engage forward contacts b and b. The cable is connected to the armature b by wire 1 and the armature b is connected to earth at g. The back contacts 12 and b of the respective arn'iatures are connected to the positive side of battery B by wire 2 and branch wire 3, a resistance a" being inserted between the wire 2 and the negative side of the battery which resistance is normally shunted by the wires 2 and 4 and the armature c of a relay 0 which normally engages a back contact 0 The forward contacts I) and b of the transmitting relays b and b are connected to the positive side of the battery by wire 5 and branch wire 5 so that when either of the relays b or b is operated (with the relay 0 in its normal position and the shunt around the resistance 1- thus closed) positive or negative impulses will be transmitted to the cable in the usual way. That is to say, if the relay 6 should be operated its armature b will move to the forward contact 5 and a circuit will be established from earth 9 to armature 7), back contact If, wire 2, contact 0 armature 0 and wire 4 to negative side of the battery, thence by branch wire 5 and wire 5, contact 6, armature and wire 1 to the conductor a. If relay 6 should be operated its armature will move to the forward contact 6 and a circuit will be established from earth at 9 through armature 6 forward contact b wire 5, branch wire 5 to the opposite side of the battery, thence by wire 4, armature 0 contact 0 wire 2, branch wire 3, back contact I), armature b and by wire 1 to conductor a. In other words, these positive and negative impulses would be supplied to the cable by connecting the negative side of the battery to earth and the positive side to cable and the positive side to earth and the negative side to cable in the usual way upon the operation of the relays b and b.

It will be seen now that if the relay 0 is operated when either a positive or negative impulse is transmitted by the operation of one of these transmitting relays b or 6 the shunt around the resistance 1" will be open and the impulse sent by the operation of either of the transmitting relays b or b will have its potential reduced to the extent of the resistance 1- (which will thus be brought into the circuit) in either case.

For operating the printing devices I preferably employ a five unit code and each automatic sending device will, therefore, be provided with five circuit closers, and these circuit closers will be ermanently connected to the usual constant y rotating distributor which will be in any of'the well known methods synchronized with similar distributing devices at the receiving end.

11 providing for sending two separate messages in one direction I employ two of these transmitting devices or rather two sets of circuit closers preferably permanently connected to the revolving parts of the distributor and I so arrange the circuits from these circuit closers that those constituting one set or one transmitter send only positive impulses and the other set send only negative impulses.

In Fig. 1 of the drawings, I have shown two such transmitters, each composed of one set of these circuit closers. The one adapted to said positive impulses, for instance, I will call transmitter A and the other adapted to send negative impulses I will call transmitter A, it being understood that each of these different transmitters will be operated by a separate punched tape in the usual way but each tape carrying the code characters for a separate and distinct message.

As the particular method for operating these transmitters and sending the impulses to the cable through a distributor D will be the same as now generally employed, a brief description only of this operation will be necessary. It may be stated, however, pre- 7 liminarily that inasmuch as five code bars are used on the receiving printers, each operated by a relay in response to an impulse of a polarity for that particular printer, impulses of an opposite polarity from that utilized by the particular printer are suppressed.

Where printers are employed'in which relays are used adapted to be operated by impulses of opposite polarity, that is, positive and negative for each printer, the arrangement will be somewhat difierent and this particular part of my invention will be made the subject-matter of a separate application.

For the present it is only necessary to keep in mind that when a message is being sent by transmitter A positive impulses only representing the particular character sent) are transmitted and the negative impulses are suppressed. When operating transmitter A the reverse is the case, the negative impulses only are sent and the positive impulses are suppressed.

\Vith the above explanation it will be seen upon reference to Fig. 1 of the drawings that the contacts 1, 2, 3, 4, and 5 of the distributor D are connected to the circuit closers b, b b b 6 and b of transmitter A by wires 11, 12, 13, 14 and 15 and the circuit closers e e e e, e of transmitter A are connected to the same contacts by branch wires 11, 12*, 13*, l Pand 15 and armature. .tained if either or all of these circuit closers these contacts (i d, (Z etc., are connected by wires 6, 7, 8, 9 and 10 to one side of relays h, 77?, h h and k and that contacts 6 e, e etc., are connected by wires 6, '7, 8 9 and 10- by a common battery Wire 16 to one side of a battery 13, the other side of which 1s connected by a common battery wire 17 and corresponding branch wires to the other side of the relays h, if, h etc. The result of this arrangement is that whenever the circuit closers of a corresponding number or position in both the transmitter A and A are in their normal or back position the circuit for the relays h, k and 72, etc., are closed, but in case either one of the said circuit closers has been operated the circuit for that particular relay k if, etc., will be Open and the armature h, h", h and h of that particular relay will be released and fall back opening the circuit as will be more fully described hereinafter. The forward contacts d, d", d ,'d and (Z of the transmitter A are connected by the common wire 18 to one side of relay 5 the other side of which is connected by wire 19 to'battery 13 the other side of which battery is connected by wire 20 to the revolving arm f of the distributor. The forward contacts e e, e, e and e of transmitter A are similarly connected by wire 21 to one side of relay 5 the other side of which is connected by wire 22 to battery B It should be noted that relays and b have two sets of windings for the purpose hereinafter more fully explained. One set only is inrluded in the circuit thus described. From the description thus far it will be noted that it in-thc operation of the distributor D one of the circuit closers 0Z d (2 etc., of the transmitter A is operated a circuit will be established through that particular circuit closer, for instance (1 through wire 12, contact 2 of the distributor to the arm 7' (which will be resting on contact 2 at that time) and through wire 20, battery B and Wire 10 to one coil of the relay 7) and through wire 18 to the contact d upon which the circuit closer arm (1 is resting at the time; the movement of the circuit closer (Z from its back contact will have broken the circuit for the relay k permitting its armature h to drop back breaking the circuit through this A similar result would be ob- Hit . should be successively operated against their forward contact and away from their back contacts.

If a circuit closer in transmitter A should be operated as the distributor D is revolving, circuit closer e for instance, a circuit would be established from said circuit closing arm by wires 13 and 13 to the third contact of distributor D on which the distributor arm 7 is resting at the time, thence through wire 20, battery B wir 22 and one coil of relay 6 wire 21 to the forward contact a. As these respective circuit closers can only be operated when the traveling arm f of the distributor is resting on the particular contact element which is connected with that particular circuit closer an impulse can be sent from that particular closer only, as the others will be open.

, It will-be seen, therefore, that when one or more circuit closers of one transmitter only is operated a number of positive or negative impulses corresponding to the number of circuit closers operated will be sent into the cable through the operation of the transmitting relays b or 6 depending upon which one of the transmitters is operated and this particular impulse positive or negative will be sent to cable at the time that the distributor arm is upon the particular contact element corresponding to that particular circuit closer and consequently at the time when a synchronously moving distributor at the other end of the cable or conductor is upon the corresponding con-tact as will be more fully set forth hereinafter.

Now there remains two other conditions to be described as each have an important function to perform in the complete operation of this method or system of operating multiplex printers. One of these conditions is where one circuit closer in each of the transmitters is operated. Inasmuch as the circuit closers in each of these transmitters will operate transmitting relay 1) or transmitting relay 6 it follows that when a circuit closer in each transmitter is operated at the same time both of the relays and b will be operated with the result that the cable will be grounded through line 1, armature 0?, contact 6 wire 5, contact 6 armature b to ground and nothing will be transmitted to the cable or, in other words, it will be in a zero condition.

This is important because this zero condition is an important element in the operation of the receiving devices.

The other condition to consider is where no circuit closer is operated in either of the transmitters A or A It may be stated primarily that in this condition provision is rnade for sending reversals into the cable for each unit of the distributor, that is, as the distributor arm passes over its respective contacts there will be sent into the cable successive impulses of positive and negative current, or (in other words, an impulse of different polarity from the next preceding one), so long as neither the circuit closers in either one or the other of the transmitters A or A This is accomplished as follows: The armatures h, it, etc., of relays If, H, etc.,.are connected by a common wire 23 to one side of a battery B which in turn is connected by wire 24 and branch wires 25 and 26 which lead re spectively to one side of the second winding of the relays b and b and from the opposite end of these respective windings the circuits pass through wires 27 and 28 to contacts 2' and 2' of a relay i, the armature i of which is connected by wire 29 to one side of the relay 0 and thence by Wires 30, 26 and 20 to the distributor arm f. Relay i is a pole changing relay and is connected in a circuit from the cable or conductor a by wires 1, 31, 32, 33, 34 and armature k of a relay is which armature is connected by a wire 35 to a condenser 36, the other side of which is connected to wire 32. Relay in is grounded at g on one side and on the other side is connected through branch wire 37 and wire 31 to cable wire 1 and hence receives an impulse when either one of the transmitting relays b or b is operated. The armature it engages contacts is and 72 one of which is connected to wire 34 and the other to ground at 9 the re sult being that at each impulse sent to cable the relays i and la will be operated; the relay is from an impulse transmitted to the cable and relay 5 from the condenser discharge so that armature i will rest first upon one contact 2' and then upon the other 2' and in either case the relay 0 will be operated and the shunt through the wires 2 and 4 around the resistance 1- will be open. Assuming now that none of the circuit closers of either transmitter is operated when the contacting arm 7 of the distributor D passes upon its first contact element (1), a circuit will be traced as follows:distributor arm f, contact 1, wires 11 and 11 armature 72., wire 23, battery B wires 24: and 25, second winding of relay 6, wire 27, contact 71 armature if, wire 29, relay 0, wires 30, 26 and 20 back to contact arm f, thus completing a circuit through battery B and operating the transmitting relay b. This will send a positive impulse into the cable and will cause the relay z to shift its armature to contact i When the arm moves to the next contact member 2 a circuit may be traced from said contact 2 through wires 12, 12 armature h", line 23, battery 13, wires -24 and 26 (number 2) winding of relay 1), wire 28, contact 7?, armature 7?, wire 29, relay 0, wires 30, 26 and 20 to contact arm f thus completing the circuit through battery B and the second winding of transmitting relay 6 causing said relay to operate sending a negative impulse to the cable; this being repeated as the arm f contacts successively the different contacting elements of the distributor, sending for each unit in the rotation of the distributor an impulse of opposite polarity to the cable. Inasmuch, however, as relay 0 will be operated whenever either transmitter relay I) or b is operated through its second winding the shunt around the resistance 1 will be open at 0 and these successive reverse impulses to cable will pass through the resistance 1" and consequently at a lower potential.

This explains the different character and. the different characteristics of the impulses which will be transmitted for the different code combinations from the sending end whether sent from one or both of the respective transmitters A and A.

It remains to describe the circuits and apparatus at the receiving end to determine how these impulses and their characteristics are employed to operate the code bars of the printers atthat end.

Referring now to Fig. 2 I will proceed to describe the operation of the receiving apparatus and circuits by which the printing devices are operated. There is connected to the cable or conductor a and the artificial line a a main receiving relay m which is preferably of the suspended coil type and provided with the standard circuits for such receiving instruments in cable practice. I preferably use this receiving relay m in the nature of a galvanometer having a mirror on the suspended coil adapted to reflect a beam of light from a lamp L passing through suitable lenses to a resistance device consisting of several elements which elements are of such a nature that their conductivity will be varied under the influence of light, such for instance as selenium. I preferably employ three of these elements 8 s and 8?, although the element a is divided into two sections, one section being adjacent to each one of the elements 8 and 8 Each one of these elements is connected in a circuit with battery to the primary of a transformer; these transformers being shown at T, T, T, a battery to supply these circuits being indicated by B. Battery wire 38 to one side of the battery B with its branches 39 and 40 connect one side of battery B to one side of the primary p of each of the transformers T T T Wires 41, 42 and 43 connect the opposite end of the transformer primaries to the rea common battery wire 44, with branches,

connect the opposite sides of these elements to the other side of the battery B.

Now if the relay m should receivev a positive impulse of normal strength such as is impressed on the cable when the resistance r of the sending apparatus is shunted, the beam of light will be moved to the left across the left half of the element 8 and rest on the element 8. The result will be to change the resistance of these elements causing a disturbance in the primary of the transformers T and T and induce a current in the secondary windings of these transformers. If a negative impulse of the same strength should be received on relay m a beam of light will be moved to the right across the other half of the sensitive element 8 and onto the sensitive element 8 This will cause a change in the primary of the transformers T and T setting up by induction current in the secondaries of these transformers.

Now, if a current of either polarity but of less potential such as would come into the cable from the sending end with the resistance r in the circuit this beam of light would move only far enough to rest on one section or the other of the sensitive element 8 hence the transformers T and T would not be affected and the transformer T 3 only have a current induced in its secondary.

Connected in circuit with the secondaries of the respective transformers T T and T are relays R R R preferably of the suspended coil type and Whose coils are respectively provided with tongues t t i these respective tongues in connection with forward contacts t", 25 t form circuit closers for local circuits which include local relays of, n? and n and batteries B 6 and B so that whenever either one of the relays R, R and R is operated one of the relays n if, n will be correspondingly operated.

For the printing mechanism I employ two distributors D and D the distributing arms of which will be preferably located on the same shaft and synchronized with the distributor D at the sending station in any well known manner. For the code bars of the respective printing devices of which in this case there will be two, I employ the usual code bar relays which are indicated here as CB CB CB CB and GB for one printing device and CR CR CR CR and CR for the other printing device.

It will be noted that the distributing arms 7 and f of the respective distributors D and D normally electrically connected by wires 45 and 46 through batteries B and '13, this circuit passing through the respec- CB CB CB and GB of what may be called No. l printer are connected to the respective contact elements of distributor D by wires 51, 52, 53, 54 and 55. The respective code bar relays CR CR CR, CR and GB of what may be termed the No. 2 printer are connected to the contact elements of distributor I) by wires 51, 52 58, 54 and 55". A common return wire 56 connects the opposite ends of each of these relays to the forward contacts 72. and n of the relays n and n If in this situation a positive impulse of normal strength is received by the cable relay m, a beam of light Will be deflected to the left across one section of the sensitive element 8 and onto the sensitive element 8 which through the transformers T and T will operate the relays R and R This will in turn close the circuits for relays n and n at contacts F, t and t, t, causing relays n and n to operate. As the armature n of relay n moves away from its back contact the circuit between the batteries B and B will be broken. As the armature n moves away from its back contact by the operation of relay n the circuit will be broken at this point also and will remain broken so long as the relay n is energized even though the relay a should be deenergized. As the armature 11. moves to the forward contact a a circuit is established from battery B through wire 47, armature n, contact a, common wire 56 to one side of each of the code bar relays of No. 1 printer and if at this particular moment the contacting arm 1 is resting for instance on No. 2 contact t at particular code bar relay will be operated.- If it should rest on any other contact the corresponding relay willbe operated. If the light should be held over by a succession of impulses as many code bar relays will be-operated as there are impulses and hence the code bars of the printing devices will be properly set for printing.

If a negative impulse or set of impulses should.- be received on the cable relay m the beam of light would move to the right cross ing the right hand section of the sensitive element 8 and onto the sensitive element 8 which would successively operate relays R and R Relay B. would operate relay n which would break the circuit as before between thebatteries B and B at n and the operation of relay B would close the circuit for relay n at contact t causing relay n to operate, bringing its armature 12. into engagement with forward contact a and breaking he circuit between the batteries at the back contact of this relay. A circuit would thus be established from battery B through wire 46 to the contacting arm f of the distributor D and throu h this arm and through the contact it may e resting upon to the particular code bar relay of No. 2 printer Which isconnected to that particular contact thence back through common wire 56, contact a armature 11.", wire 50 to battery B".

I have thus described the means .for

operating either code bar of either printer synchronously with the operation of either circuit closer of either transmitter at the sending end as these positive or negative impulses can only be sent into the cable by the transmitter A or the transmitter A at a time when the contacting arm f of sending distributor D is restin upon the corresponding contact with whic the distributing arm of the receiving distributor D or D is engaging at the re-' ceiving end.

I will next describe the operation when an impulse of lower potential is impressed upon the cable which it will be remembered will occur when no circuit closer of either transmitter is operated and which results in sending to cable successive impulses of opposite polarity but of lower potential. This will result in the operation of the cable relay as). p

m to a lesser degree and cause the beamof light to move successively to the different sections of the sensitive elements 8 only and inasmuch as neither the sensitive elements .9 or s? will be affected, relay It only will be operated through its transformer T. The operation of relay R in turn will energize the relay n thus breaking the circuit between the batteries B and B so that as the distributing arms f and 7 pass over the distributor contacts neither ofthem will find battery and hence none of the code bars in either of the printers will be operated.

It remains to describe what will take place when a circuit closer in each of the transmitters is operated at the same time. It will be remembered that when this takes place the cable remains in a zero condition, no impulses of either sign being impressed thereon. In that case the cable relay m is not afl'ected. The beam of light remains in the zero position between the respective sections of the sensitive element a and neither of the relays R R R are operated and the circuits and apparatus remain in the normal position as illustrated in Fig. 2 of the drawings. If this should happen when both of the distributor arms 7 and f? were on the third contact for example of each of the distributors (which would be true in case the third circuit closer of each of the transmitters A and A were operated) these contacting arms would find battery on each of these contacts No. 3 in the respective distributors and I would have a circuit from contacting arm f through wire 45, battery B wire -47, armature n, wire 48 armature a, wire 49, armature a, wire 50, battery B wire 46, contacting arm f through the third v form the printin are operated at the same time, the correspondlng code bar relays of both of the printers wiil be operated by the sunchronous operation of the distributors D and D The moment that the circuit, closer of one transmitter is operated and the corresponding circuit closer of the other transmitter is not operated then a positive or negative impulse will be sent, depending upon whether it was the A transmitter or the A transmit ter that was operated.

Inasmuch as it is now common practice to operate printers of this character and to provide means for word spacing and for performin the printing operation and also for propei ly synchronizing the distributors, these operations and the devices. for accomplishing them are not described. The particular installation to which my improved method of sending signals is shown applied is the five unit code now in use by the Western Union Telegraph Company and others.

The same method of sending and receiving.

signals, however, can readily be used in connection with any of the other well known printing systems by simplemodifications of. the local circuits to suit their particular conditions.

By the use of the two transmitters and the two printers employing the five unit distributor,- thirty-two different combinations can be secured for each of these transmitters and printers which are ample to provide for all the characters used in printing telegraphy with upper and lower case, spacing key shift, etc.

Having thus described my invention, I claim 1. In a system for sending and receiving a plurality of messages over a conductor, means for sending current impulses of different polarity for one message and of the opposite polarity for a different message, and causing a zero condition where impulses of; opposite polarity appear si-' multaneously in diflerent messages, and separate means at the receiving end operated by the positive and negative impulses and by the zero condition of the cable, as set forth.

2. The method of operating simultaneously a plurality of printing devices so as to receive separate messages in the same direction over a single conductorv at the same time which consists in using for transmitting each message positive and negative impulses with a plurality of variations of current for certain operations and a zero condition where impulses of opposite. polarity appear simultaneously in different messages as setforth.

3. The method of simultaneously operating two printing devices so as to send and receive two messages in the same direction over a single conductor at the same time which conslsts in employing two transmit- "ting devices, one adapted to transmit positive impulses and the other negative impulses and producing a zero condition on the cable when corresponding units of the respective transmitters are operated at the same time and causing the operation of one of said printing devices from impulses of one polarity and the operation of the other printing device from impulses of opposite polarity and the operation of similar units of both printing devices from the zero cable conditions as described.

4. Ina system of printing telegraphy, two transmitting devices having the same code units connected to a single distributor, two printing devices each with a distributor synchronized with the sending distributor, one of said transmitting devices being adapted to send positive impulses which shall be received on one of the receiving distributors and the other transmitting negative impulses which will be received on the other distributor and to cause simultaneous operation of corresponding parts in both printers when the corresponding unit of both transmitters are operated, substantially as described.

5. The method of telegraphing over a submarine cable which consists in utilizing current impulses of, one sign for operating a translating device and impulses of the opposite sign for operating a diflerent translating device and a zero condition of the cable for simultaneously operating both translating devices.

6. The method of transmitting a plurality of messages over a single conductor which consists in using current impulses of one polarity for one message and current impulses of the opposite polarity for the other message and creating a zero cable condition when two impulses of opposite polarity are impressed on the cable and utilizing these diflerent current impulses and zero condition for operating diflerent translating devices.

7. In a telegraph system for transmitting a plurality of messages over a single conductor, means for sending positive impulses for signals in one message and negative impulses for signals in the other message, and creating a zero condition when impulses of the same polarity occur, and means for utilizing the positive and negative impulses for causing a beam of lightto move to one light affected element in response to the innpulses of one polarity and to a different light affected element by impulses of the opposite polarity and. translating devices from each oi; said light atl'ectcd elements to be operated in response to the impulses of either polarity and a. separate translating device adapted to be operated when neither of said elements are ailectcd or when the light is in zero position.

8. In a system of printing telegraphy, a plurality of ninting devices each having a plurality of. operating units, alight refleeting mechanism operated in different di rections and to different degrees in the same direction by different signal. impulses, a plurality of light-ailected-resistance-eloments in the line of travel of said reflected light, one for each degree oi light movement, said resistance elements being severally connected to and adapted to operate dilierent translating devices, said different translating devices being arranged to operate the diiierent units of the several printers in re sponse to difi'eren't current impulses as set forth.

9. In a telegrephing system as described, for receiving and translating telegraph impulses of different impulses for different messages and which embodies a plurality of sets of light affected resistance elements, and means for illuu'linating said resistance elements in response to the impulses of dif ferent polarity and a translating deviceconnectcd to and operated by the change in resistance of each of said elements as the same is illuminated, said translating device being arranged to operate recording devices to record different signals or signal elements when the light is moved in either direction and a separate translating device adapted to operate automatically when neither of said resistance elements are illuminated, as specified.

10. The combination with a plurality of sending devices connected to a single distributor at one end of acable, means for causing current impulses of opposite polarity and of difi'erent potentials of the same polarity under different conditions of operation of said transmitters, receiving and translating devices at the other end of the cable embodying a light reflecting galvanometer moving in opposite directions and to varying degrees in the same direction in response to said transmitters, a. plurality of sets of light-afi'ected-resistanceelements and atranslating device connected to each element and a recording device operated by each translating device whereby the different recording devices will be operated by the dillerent light-affected elements when the light is moved to dillerent positions in either direction as set forth.

11. In a system of printing telegraphy, a plurality of transmitting devices at one end of a conductor and a plurality of printers at the other end, means connected with said transmitters for causing impulses of opposite polarity and of different potential of the same polarity to be impressed upon the conductor and means at the receiving end to produce a certain condition of the respective printing devices by impulses of different polarity and a different condition by impulses of different otential of the same polarity and a thir condition by a zero condition of the cable and utilizing these various conditions for simultaneously operating a plurality of printers as set forth.

12. The method of receiving a variable potential telegraphic current consisting of positive, negative and zero impulses, Whereby two simultaneous telegraphic messages are recorded over a, single conductor by the employment of three or more selenium or other light-affected resistance elements so arranged that a beam of light responding to the variations of either positive or negative and the zero impulses operate telegraph printing mechanism to record two separate simultaneous messages.

In testimony whereof, I have hereunto set my hand this 22nd day of April, 1920.

WILLIAM M. BRUCE. JR,

Vlitness CHAS. I, VVELQH.

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