US2498695A

US2498695A - Telegraph receiver

Info

Publication number: US2498695A
Application number: US744010A
Authority: US
Inventors: Mcwhirter Eric Malcolm Swift; Dunn Roland Harris; Lennox Peter William
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1946-02-19
Filing date: 1947-04-25
Publication date: 1950-02-28
Anticipated expiration: 1967-02-28
Also published as: FR942202A; US2668870A; ES176831A1; DE911736C; FR63212E; GB676588A; DE914739C; CH284954A; GB636668A; BE471306A

Description

1950 E. M. s. MCWHIRT-ER ETAL 2,498,695

TELEGRAPH RECEIVER 3 Sheets-Sheet 1 Filed April 25, 1947 gven t rv- /z/% W Alto ney Feb. 28, 1950 MOWHIRTER ETAL 2,498,695

TELEGRAPH RECEIVER I Filed April 25, 1947 Z Shets-Sheet 2 Patented Feb. 28, 1950 TELEGRAPH RECEIVER Eric Malcolm Swift McWhirter, Roland Harris Dunn, and Peter William Lennox, London, England, assignors to International Standard Electric Corporation, New York, "N ."Y.

Application April 25, 1947; Serial No. 144,010 In Great Britain February 119, 1.946

Section ;1, Public Law 690, August 8, 1946 Patent expires February '19, 1966 Claims. 1 This invention relates to telegraph receivers. A telegraph receiver mustin general comprise a means for timing the periods occupied by the Successive elements of the .code. This ;is generally done by means of rotating mechanical parts and great accuracy of manufacture is necessary for these parts.

According to one feature of the present invention there is provided a receiver fora telegraph code comprising. a time base derived by electric discharge services for timing the in,- tervals occupied by the elements of said code, and means for determining the kind of elements received in each of said intervals.

According to another feature of the invention there is provided a receiver fora telegraph code comprising means for generating an evenly spaced series of electric impulses, means .ior timing the intervals occupied by the elements of said code by the intervals between saidimpulses and means for determining the ,kind .of element received in each of said intervals.

The invention will be described as. applied to the reception of start stop teleprinter codes and as so applied a receiver according to one feature of the invention comprises an electric impulse generator for generating, ,an ,evenly spaced series of impulses, ,means responsive to the start element of a code signal for starting said impulse generator into. operation, and means for timing the intervals occupied :by :the elements of said code by the intervals betweensaid impulses and means for determining the :kindpf element being received at the ,middlewof each of said intervals.

Preferably the receiver according to the in.- vention comprises a chain of gas filled electric discharge devices which are caused to'be rendered conducting sequentially by sequentialimpulses and in the case of a receiverfor start. stop teleprinter codes the electric impulse generator that is started into operation by the receipt of the start element of a code delivers an impulse to the electric discharge device corresponding to the start element of the codeaf-ter a delay-equal to half the period of time allotted to the start element. Each electric discharge device causes the succeeding device to become conducting when the next impulse is applied so that these successive devices become conducting at the midpoint of the successive elements and the time interval to be occupied by the signal is determined by the chain of devices.

The invention has been devised primarily for use in the electric signalling system claimed :in

copending U. S. patent application Ser. No. 744,009. In thissystem the closure of contacts individual todifferent pieces of apparatus .at one or more substations causes the transmission of pre-determined teleprinter codes individual to the particular contacts to a supervisory station where a device individual to the contacts at the transmitter is operated upon the receipt .of the predetermined code signal. The invention accordingly provides a receiver tor predetermined telegraphcodes. comprising for each said code a chain of .gasfilled .electricdischarge devices, one for each element of the code, means for setting the successive devices .of each chain so as to cause .each to .be rendered conducting only .upon the simultaneous occurrence vof the preceding device in the chain .being conducting and an elementiof, the required kind being received means for causing..-successi ve elements of the code to be applied to successivedevices in the chain and means operative. upon the last device in the chain :becoming conducting .to .cause the receipt of the code to'become operative.

It is preferred that the codes .used in such a system should be chosen @sothat the earlier occurring elements areas far as possible common to a plurality of codes and :the several chains of electric discharge devices .are combined to the extent that devices representing elements common to .-a plurality of codes, are provided and are connected so as to ,be common to the like plurality-pf chains ofsuchdevices.

This principle is readily extended to provide reception of the full number of codes possible.

Thus for astart-stop teleprinter codeusing five code elements, thirty two different combinations are possible. There are thus thirty two chains of electric discharge devices required but the number of such devices is reduced by arranging one such device for the start element which is common: to all the combinations. This device is connected to ,a pair of devices forthe second element ,of the code, one for a marking element and one for a spacing element. The start hecomes conducting .in response to the start element and impresses on each device of the said pair of a potential tending to make it conducting. When the first code element is received it impresses a second potential on that one of the pair that corresponds to the-kind of element. The two potentials added together make one of the pair conducting. Each device of this pair is connected to twofurther devices for the next element and so on in geometrical progression. In this way any particular code received progresses along only one chain of electric discharge devices and only one device corresponding to the last element of the code combination becomes conducting and indicates the receipt of that particular code combination.

Although this completed chain of electric discharges in one sense times the telegraph code, it is preferred to use a separate means forthis purpose and in the preferred form this separate means consists of a separate pilot chain of electric discharge devices rendered conducting sequentially by the application thereto of an evenly spaced series of impulses.

The invention will be better understood from the following description taken in conjunction with the accompanying drawings in which:

Figs. 1 and 2 together form one circuit diagram, Fig. 1 showing the pilot chain of tubes and a receiver for one predetermined code and Fig. 2 the circuit of the impulse generator and the telegraph relays receiving signals from the line;

Fig. 3 shows diagrammatically how tubes of the receiver may be arranged for a certain number .of code combinations; and

Fig. 4 shows diagrammatically the arrangement of tubes of the receiver for a complete 5- unit code receiver.

Referring to the drawings and first to Fig. 1 there are shown two trains of three electrode gas-filled cold-cathode tubes. The first or pilot chain consists of seven tubes I 'I, one for each element of the code. These tubes are connected each to the next in the chain in a manner similar to that shown in U. S. Patent No. 2,421,005, but modified in an important respect.

All the tubes are similar so that only one need be referred to in detail. Tube I comprises an anode 8, a control electrode 9' and a cold cathode II]. Inorder to render the tube conducting the gap between the control electrode 9 and the cathode I!) must be ionised and a positive po-' tential must be applied to the anode 8 with respect to the cathode. So long as this potential is 130 volts or more, the minimum ionisation current produced by a voltage of about 70 volts between control electrode 9 and cathode I0 is sufiicient to cause current to flow betWeen anode 8, and cathode IEI. As the potential applied between anode and cathode diminishes below 130 volts, the ionisation current between control electrode 9 and cathode III and consequently the potential applied between them, that is needed'to render the tube conducting, increases rapidly.

When the tube I is conducting, current flows through resistances II and I2 between cathode I0 and earth. In U. S. Patent No. 2,421,005 the resistances between the cathode and earth were so proportioned'as to give a voltage drop of about 35 to 40 volts thereacross and the cathode was connected directly to the control electrode of the succeeding tube (such as tube 2). The source of potential I3 for the anodes of tubes I' 1 is derived ultimately from the mains and if the mains voltage falls, the voltage applied to the anode of tube 2 falls and the nominal voltage applied to its control electrode from the cathod circuit of tube I also falls.

In the present circuit therefore, resistances II and I2 are proportioned to give a voltage drop of twice that previously provided between cathode and earth and the junction point of these resistances is connected (over a resistance I4 as previously) to the control electrode of tube 2. The fall in the nominal voltage applied tov the control electrode 9 of tube 2 due to a given fall in mains voltage is then less than before. Moreover the voltage drop between the source l3 and the anode of tube I is reduced so that tube I is more easily extinguished by tube 2 becoming conducting. The voltage-drop across tube I when conducting is about 70 volts so that the anode of tube I is about volts above ground potential. As the anode of tube 2 is connected directly to the anode of tube I and the cathode of tube 2 is at earth potential when the tube is not conducting, the voltage applied between the anode and cathode of tube 2 is held, even if the mains voltage varies, above the value at which minimum potential difference between control electrode and cathode will cause the tube i ecome conducting.

In the initial condition of the circuit of Figs. 1 and 2, tube I is conducting and a potential difference is impressed from its cathode circuit between the control electrode and cathode of tube 2. This potential difference is about 35 volts, which is insufficient to cause the tube to become conducting, the potential difference required for this purpose being about '70 volts.

The incoming line I5 Fig. 2 is connected over windings of telegraph relays I6 and IT to ground. As in the normal, non-signalling condition of line I5 marking potential is impressed thereon at the transmitting station, the contacts I8 and I9 of these relays are in marking position. The cathode of tube I Fig. l is connected over a conductor 20 to the marking contact of contacts I9 and thus through a condenser 2I and ground. Condenser 2I is thus kept charged.

Fig. 2 shows the circuits of an impulse generator and the means by which it is started into operation. The impulse generator comprises two pentodes 22 and 23 connected in well known manner as a multivibrator. The anode potentials are supplied from a source stabilised by means of a neon-tube stabiliser 24. The normal grid potentials are adjusted by means of potentiometers 25 and 26, the sliding contact on 25 serving to adjust the frequency and that on 26 the relative times of operation of the two tubes. The impulses are derived from the grids of pentodes 22 and 23, these grids being connected over respective condensers to the grids of triodes 21, 28 so that the changes of potential on the grids of pentodes 22 and 23 being thus differentiated to produce positive impulses on conductors 29 and 38 connected to the anodes of those triodes.

The multivibrator is held in non-operating condition by the cathode of tube 22 being normally connected to positive potential. A three electrode cold cathode tube Si is normally conducting and current therefore flows through resistance 32 connected to the cathode thereof, the positive end of this resistance being connected to the cathode of pentode 22. There is a second three electrode cold cathode tube 33, which is normally non-conducting, the anode of which is connected over a condenser 34 to the anode of tube 33.

The spacing contact of contacts I 9 is connected to earth over the primary of a step-up transformer 35, the secondary of which is connected to the control electrode of tube 33. When therefore the start element of a teleprinter code combination is received and contacts I8 and I9 of relays I6 and I! change over to spacing position, condenser 2I is discharged through the primary of transformer 35. The resultant potential across the secondary of this transformer 35 is impressed between control electrode and cathode of tube 33 and is sufiicient to ionise the gap between those anes oes electrodes and :theitube 33 becomes conducting. The iIItEFCOHIIGCtlOD- OTI'thB anodes :of-etubes Mxand 33 through condenser 34Jres1I1tsin tube :3l becoming non-conducting andthe disappearanceof the positive bias on the cathode pipentode 22.

The -positivebias on. the cathode. of pentode 22 haswprev-iously held. this .apentode from passing current-and the multivibrator .is thereforenormal ly' in the position .:.in lWhiCh: anode current .in pentode .23 .a maximum. .Whenzthe positive potentialon the cathode :of-tube 2'2.:is removed thelgridpf that tube becomes positive withrespect to=the cathode and the tube l 22 passes :eur-rent and the anode current rapidly :rises *to :a maximum and remains so until the :condenservconnecting the'anode of pentode 22.to:the. grid of pentodet23 has discharged. Pentode 23 then :passes current and there .is a sudden drop in-the potential of the gridof pen-toder-2 2. r Thisrsudden :drop inypotential lis differentiated .:by. condenser 3fixand .a positive pulse created :on .conductor..;29 connected to the lanodez oftube 121.. The .periodiof the multivibrator may belsetsso that this :pulse occurs milliseconds after :the commencement of -its operation and thus at itheim'id-point of fthe periodof milliseconds .ior :the :start element of theincoming signal (for a teleprinter. signalling speed of 50 bands).

Conductor: 29.15 connected to a conductor .3"! which .;.in turn :is connected over an individual condenser resistance combination to the control electrodes :of :tubes'2 ,1. The value of the potential thus impressed on these control electrodes .is winsuflicient tosionise the gap between controlelectrodeand cathode-of anyof the tubes, but :added :tothe potential- 'imptessedon the control electrode-of .tube 2" from thecathode .circuit :of :tube l :is -suflicient :tocause tube Ii-to become conducting.

When tube 2 becomes conducting a potential is impressed from its cathodo circuit uponthe control electrode of tu'be (and ailso upon the control electrode of another tube to bere'ferred to resent1 and upon the next occurrence -of an-impulse onconductcu' 3! i. -e. after a-period-of 20 "milliseconds, tu'be-3 beeomesconducting. in turnimpressesa potential upon tube t. in this way tubes 3, '4,"-'5 ii-and "1 become conducting on the "occurrence of successive impuls'es.

It shouldbe noted-that "the anodes' of .all tl re tubes I 'l are connected to positivepoterrtial over a common resistance 'ttyvvhich-is -of' such value thatwv'hen a tube suchas "tube 2' becomes conducting. the potential uponthe anode'ofany other tube,such as l,that'is at'that'm'oment-conducting is "depressed "below "the value necessary tokeep thetube conducting whenronl a'verylow potential'is applied across "the gap between control electrode and cathode. The consequence is that when any tube in the chain -l ...""l "becomes conducting the. preceding 'tube in the chain becomesnon-conducting.

Thetubes 1| '1 correspond .to. the different elements. of. a .startestopfive unit ,teleprinter code. Tube 1 .is apilot tube, normally conductingand corresponding to the stop. e'lementlof the code. Tube 2 corresponds tothe .start element of the code...and tubes v3 to .-the. code elements. The tubes .2 Sl -operated sequentiallyby ,the impulses on conductor 31, time ltheintervalsoccupied by the elements of the :code, becomin conducting at the mid-points of the elements allottedi'to thecode.

The cathode circuit of tube It deaconnected over conductor-:39 tto :the. 2901117130.]. electrode. sofas. :col-d cathode tube 40 (Fig. 2) which control electrode also :connected :toaconduetor The impulse generator applies; anxlimpulse JtO..:-CQD-d1l0t.l' 123i ten milliseconds after. each impulse aplll'iedto to the connection/between the anodes :of tubes .34

and 33 over aoondenser.3:4,;tube.33:becomes nonconducting. Another ieftectlof tube l becoming conducting istotimpressa positivepotential upon the. cathodeuof pentodeizoand so st p he-impulse generator. Tube. 1551318 zconnected so as. :to be self-extinguishing.

The secondary 59f transiormerrdil .-.:is.q.con.-nect.ed over .a; conductor '42. to the-control {electrode of tube letFig; 1') ;and the impulse delivenedwhen tube 4:10 becomes conductingalso (causes tube i to becomeconducting. JT-Ilube V1'! is thereby :rendered non-conductin Soiarnorreference hasibeemmade to {the efi fict oizthereoeipt of the' .cod.e lelementscof;a.signal. Fig. 1 :shows {a receiver for .a, particular modecombination. receiver consists of five tubes 43 14.1 .correspondin to the :fiwe mode-elements of rayfive unit teleprinterpode. The anodes-40f all these tubes .are co-nnecte'd together, and through a resistanceASto a p0SitWe.-S0ll1tGeA9. .illhe cathode circuit .ofaitube is -.connected .-to the control electrode of tube A3 and thencathode-circuit of each :of the tubes .-:43 -46. is-;connected-.to-the controlrelectrode-of the nenttubeein the-"chain in the same .manne as theltubes I l areconnected together.

. Thezeontrol eleptrodesioftubes 43 pillar-.6 connected through individualcondensersand resistances to either of two conductors 15.0 out! r which in turn are connected-to the spacing and marking :contacts mespectively of relay .15. The connections between .thercontrolielectrodes of the tubes :43 47 and conductors-:50 and-iluare preset ,in accordance withra particular code combinatiomin the case. shown, .mark, space, space, space, mark. The operation; is as follows:

Tube- 2 .is made conducting-when the-,startelement of a teleprinter signal .is received, as .described above, and a .potential is thereby impressed not only between. control electrode and cathode of tube .3-asdescribed above, but also between controlelectrode and cathodeof .tubedt. The second impulseon conductor ,29 occurs ,at an interval of 20. millisecondsafterthefirstimpulse, i. e. in the middle of the interval allotted to the first code elementpf .the received signal. Conductor 2.9 is connected to the moving tongue ofcontacts t8 and ifat this momentama-rking impulse is being .rec,eived,.s,o that contacts i8. are in marking position, this impulse is applied over conductoril to the control electrode of tube-43. The potentialdue to this impulse, added .to the potential impressed vfrom the cathode circuit of tube.2 causes tube .43tobecome.conducting. The cathode circuit .oftube .43 impresses apotential on'the-control electrode .of tube .44. ..If, on .the occurrence of the next impulse on conductorifl, contacts .18 are *inspacing position, the-potential of this impulse .is. applied iover condudtorfifl .to the ;control electrode of tubes, .and' .tube 44 becomes 'conducting'and tube'43 is made nonconducting.

If, on the other hand, contacts l8 were in spacing position on the occurrence of the second impulse on conductor 29, tube 43 would not have been made conducting. In this case tube 43 would not be made conducting upon any subsequent impulse. Also if tube 43 has been made conducting because the first code element is a mark, but the second code element is also a mark so that on the occurrence of the third impulse on conductor 29 contacts l8 are in marking position, tube 44 would not be made conducting. Tube 44 will however be made conducting on the occurrence of a subsequent spacing element forming part of the code combination.

It will be clear that if the code combination received be that for which tubes 43 to 41 is set these tubes will be made conducting in succession, but that if any other code combination be received, tube 47 will not have been made conducting by the time the code combination has come to an end and the creation of impulses from the multivibrator 22, 23 has ceased. If the correct code combination has been received and tube 41 has become conducting, current flows from a point in the cathode circuit of tube 4! through a rectifier 52 in the forward direction to charge a condenser 53 in such sense as to apply positive potential upon the grid of a triode vacuum tube 54 whereby a relay 55 connected between the cathode of tube 54 and ground is operated. Relay 55 closes its contacts 56 to operate a meter 51 or other indicator. The rectifier 52 is shunted by a resistance 58 which allows the condenser 53 to discharge in about half a second.

An additional cold-cathode tube 59 is provided having its anode connected to the anodes of tubes 43 41. The control electrode of tube 59 is connected to the conductor 42, so that when, at the end of the period allotted to the receipt of a start-stop teleprinter code tube i is made conducting by an impulse from the secondary of trans-- former 4| over conductor 42, as above described, tube 59 is also made conducting. anode connection ensures that any of the tubes 43 41 that may then be conducting is made non-conducting. Thus the tubes 43 41 are ready for the receipt of a further code combination, whether the code combination for which they were set had, or had not been received. Tube 59 will be rendered. non-conducting during the receipt of a subsequent code combination if any of the tubes 43 41 then becomes conducting.

It will be clear that as many sets of tubes such as 43 4'! may be provided as there are code combinations to be received, each set being connected up so that, upon the receipt of the correct code combination a relay such as 55 will be operated.

It is however possible to choose the codes to be operative at the receiver in such manner as to reduce considerably the number of electric discharge devices required. This may be done by choosing the codes so that the earlier occurring elements are as far possible common to a plurality of codes. The several chains of electric discharge devices are then combined to the extent that devices representing elements common to a plurality of codes are provided and connected so as to be common to the like plurality of chains of such devices.

Fig. 3 shows diagrammatically how this can be done for four and eight codes respectively. Each of the circles represents a cold-cathode tube.

The common Those tuba that have control electrodes con nected to the marking conductor I, Figs. 1 and 2, are shown as black circles, those that have control electrodes connected to the spacing conductor 50 are shown as open circles. One arrangement of tubes for four codes is shown above the dashed line. It will be noted that the first three tubes 60, 6|, 62 arranged for mark, space, space as the first three elements are common to all four codes. For the fourth element two tubes are provided 63 and 64, the former for a spacing element, the latter for a marking element. The cathode circuit of tube 62 is accordingly connected to the control electrodes of both

tubes

63 and 64. Similarly for each of the

tubes

63 and 64 there is a pair of

tubes

65, 66 or 61, 68 for the final element of the code.

The portion of Fig. 3 below the dashed line shows the additional tubes needed to extend the arrangement to the receipt of eight codes, and from this it will be clear how the arrangement could be extended for the receipt of any number of codes permitted by the number of code elements used, that is 92 for a five-unit code. The letters placed in Fig. 3 opposite each tube for the final element of the code are the letters represented by the particular chain of devices that ends in that element.

In this way a complete teleprinter receiver may be constructed, as shown in Fig. 4 which is composed of electric discharge devices, apart from the two receiving telegraph relays I6 and Il and the relays such as 55 which can be arranged either to efiect the printing of a character or to perform any desired supervisory or indicating function. There are no rotating parts and mechanical wear is reduced to a minimum. The start tube 2 is shown in Fig. 4 and from this figure the connections of the remaining tubes will be clear.

When a code combination is received, only that chain of gas-filled tubes corresponding to the particular code combination is completed. Other chains are left in a condition in which one of the tubes other than the end tube of the chain is conducting when the receipt of the code combination comes to an end. All tubes that are thus left conducting are caused to become non-conducting when the tube 59 becomes conducting, so that the equipment is ready to receive a subsequent code.

It should be noted that the multivibrator of Fig. 2, may be set by means of the sliding contact on resistance 26 so that the relative periods during which it is in the respective conditions of stability are equal and this adjustment has been assumed in the foregoing description. In this condition of adjustment an impulse occurs on conductor 29 after the lapse of 10 milliseconds (assuming that the slider on resistance 25 is set for a total period of 20 milliseconds). The sliding contact on resistance 26 allows however of the adjustment of the initial period to suit distortion in the line [5, this adjustment corresponding to that which is termed orientation adjustment with mechanical teleprinters. The impulses on conductor 29 follow one another after equal periods of time, the length of which depends on the frequency of the multivibrator, determined by the adjustment of the sliding contact on resistance 25. What is claimed is:

1. A receiver for predetermined telegraph codes comprising for each said code a chain of gasfilled electric discharge devices, one chain for each element of the code; an electric impulse generator for generating a series of regularly repeated impulses, means for applying impulses from said generator to successive devices ofs'aid chains upon receipt of a code element the required kind, means to apply an impulse fr m a preceding device in a chain simultaneouslylwith said last named means, said successive devic"; in said chains adapted to be rendered conducting in accordance with the corresponding code lement, means operative upon the last devic'e'j in an operated chain becoming conducting to indicate the receipt of the code element, and means connected to each chain for restoring the devices thereof to non-conducting condition at the end of the period allotted to the receipt of the cod 2. A receiver as claimed in claim 1 comprising means for timing impulses from said impulse "generator to occur at the mid-points of the period allotted to the receipt of successive elements of the code.

3. A receiver as claimed in claim 2 in which a pilot chain of gas-filled electric dischargedevices is provided, one for each element of. the code, comprising means for rendering said j ,devices conducting successively, for periods equal to the periods of the successive elements of the code and means operative at the end of the period allotted to the receipt of a code combination/for stopping said impulse generator and for restoring the receiver into a condition to receive a further code combination. s

4. A receiver as claimed in claim 3, in which said means for generating electric impulses or said electric impulse generator comprises a multivibrator, and means for differentiating the changes of potential upon an electrode of said multivibrator to produce a series of impulses.

5. A receiver as claimed in claim 4 in which said pilot chain comprises one of said discharge devices normally in a conducting condition, means for impressing a first positive potential from said device upon a start device of said chain corresponding to the start element of a signal, disabling means for normally holding said impulse generator in one condition of stability, tele- 10 graph relays connected to respond to incoming signals, means operative upon the movement of contacts of said relays in response to the start element 01' a signal to render said disabling means inoperative, means for deriving from said impulse generator impulses timed to occur at the midpoints of the start element and succeeding elements, means for applying the first of said impulses to render said start device conducting and subsequent impulses both to render successive devices of said pilot chain conducting and to render conducting in succession devices of a chain of gas-filled devices preset to respond to elements of a particular kind, means responsive to the last device of said last mentioned chain becoming conducting to record the corresponding character and means responsive to the joint occurrence of the last device of said pilot chain becoming conducting and of an impulse from said impulse generator in anti-phase to said first mentioned impulses for restoring said disabling means and for rendering non-conducting any device of any of said pre-set chains that may be conducting and all other devices except the one corresponding to the stop element of said pilot chain.

ERIC MALCOLM SWIFT MCWHIRTER.

ROLAND HARRIS DUNN.

PETER WILLIAM LENNOX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 897,662 Roberts Sept. 1, 1908 1,068,869 Edwards July 29, 1913 2,099,065 Holden Nov. 16, 1937 2,411,441 Leroy Nov. 19, 1946 2,412,642 Wilherson Dec. 17, 1946 2,430,547 Anderson Nov. 11, 1947 FOREIGN PATENTS Number Country Date 512,827 Great Britain Sept. 29, 1939