US2050011A - Sound recording - Google Patents

Description

H. J. M CREARY SOUND RECORDING Aug. 4, 1936.

Filed June 9, 1932 3 Sheets-Sheet l Aug. 4, 1936. H, J, MCCREARY 2,050,011

I SOUND RECORDING Filed June 9, 1932 3 Sheets-Sheet 2 MI r:

Aug. 936.

H. J. M CREARY 2,050,011

SOUND RECORDING Filed June 9, 1932 3 Sheets-s 3 'IIII w W /2 m7 /06 JUL/En 0r Harald JHPEEEEPH 'M/ZMM Patented Aug. 4, 1936 1 UNITED STATES PATENT OFFICE 2.050.011 SOUND nscoanmc.

Harold J. McCreary, Lombard, 111., assignor to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application June 9, 1932, Serial No. 616,285

6 Claims. (Cl. 101-426) My invention relates in general to sound recording and has for its object new and improved methods and apparatus for the manufacture of sound records and for the production of copies of such records.

A special object of the invention is the production of master sound records in the form of a metallic tape. Several new and improved methods of making such records are disclosed.

Another object of the invention is a new and improved process of producing copies of sound records on paper tape or other similar material by printing from a master sound record.

Another and related object is a new and improved process of producing copies of sound records by stencilling on paper tape from a master sound record.

A special object of the invention is the production of cheap and compact sound records for general use comprising reels of paper tape or similar material on which sound records are printed or stencilled.

A special object of the invention is an unusually compact sound record of the paper tape type, comprising an endless single surface tape having a continuous multi-track sound record on. both sides.

A special feature of the invention is a reel for use with endless tape records of the single or double surface type. The improved reel provides for unwinding from the inside simultaneously with rewinding on the outside.

The foregoing and other objects and features of the invention will be pointed out more in detail hereinafter, reference being had to the accompanying drawings, in which:-

Fig. 1 is a diagrammatic view of apparatus for printing sound records on paper or other similar tape from a master tape sound record;

Fig. 2 shows in diagrammatic form an apparatus for producing copies of master tape sound records on paper or other tape by a stencilling process;

Figs. 3 and 4 are other views of portions of the apparatus shown in Fig. 2;

Fig. 5 is a diagrammatic view of an apparatus;

with a diagrammatic representation of a continuous sound record occupying both sides of the tape;

Fig. 13 shows a reel or spool for use with an endless single surface sound record tape, together with suitable rollers for drawing the tape from the reel and for rewinding it; while Fig. 14 is a perspective view, partly 'in section, 5 of the reel shown in Fig. 13.

I will first describe a process of making a metallic tape master sound record which is suitable for use in the printing and stencilling processes illustrated in Figs. 1 and 2. The tape used 10 may vary as to size and material. However, a tape one inch wide and about .005 inch thick is all right for the purpose. The .material may be steel, brass, or other metal. A zinc alloy known by the trade name Eraydo" is also suitable.

In brief, the process is a photo-lithographic process very similar to what is in common used in printingplants throughout the country. After being first cleansed, the metal tape is coated all over with a sensitized film. This film is soluble in water but portions thereof which are exposed to light are hardened and rendered insoluble in water or in the acid used in etching.

The treated him is next exposed in a sound recording apparatus. known in the art and therefore need not be shown or described herein. Recording apparatus which makes a record of the variable width pattern may be used. Fig. 6 shows a section of sen- 'sitize'd metal tape after exposure. The shaded area is the area which has notbeen exposed to light. 1

The exposed tape is then washed in clean water with the result that the film is washed away except where it has been fixed by the action of light. In Fig. 6 the shaded area is washed clear of the film and also the entire rear side of the tape, none of which has been exposed. The rear side of the tape is then given a coating of acid resistant varnish.

The tape may now be run through an etching solution. This. process is repeated a number of times until that portion of the tape which has not been exposed to light, the shaded area in Fig. Lisrentirely removed by action of the etching solution. The varnish and the remainder of the fllm may now be cleaned off by the use of suitable solvents for these materials.

The finished tape sound record, or rather. a section of it, is shown in Fig. 7. This is a variable width sound record. J

A- modification .oLthe foregoing process will now be described in connection with Fig. 8. This process contemplates the use of a metaltape covered with a sensitized film the same as Such apparatus is well 25 in the foregoing. Instead of exposing it in an ordinary sound recording apparatus of the variable width type, however, the recording apparatus is modified by substituting a light slit wide enough to cover the entire width of the tape. Close to the light slit and at right angles to it is stretched a thin wire which vibrates transversely ofthe light slit under the influence of a varying electric current corresponding to the sounds to be recorded. This wire casts a shadow normally at about the centre of the tape and as the tape moves past the slit in the recording process the vibrating wire will produce a narrow unexposed area in the form. of a wavy line. Fig. 8 represents a section of tape which has been exposed in this way. The unshaded areas have been exposed to light, but the shaded wavy line down the center has not been exposed.

It will be appreciated now that by suitable treatment along the line of what has already been described the metal tape can be etched through and split down. the center along the unexposed line, Fig. 8, so as to produce two similar metal tape sound records. The upper half of the tape, Fig. 8, will become a record like Fig. 7, while the lower half will become a similar sound record, except that the indented portion is on the opposite edge.

Fig. 5 shows an apparatus for producing metal tape sound records by a'method which is somewhat similar to the process described in connection with Fig. 8, but which dispenses with photography.

In Fig. 5, 2 is a reel carrying the metal tape supply, while M and i5 are reels on which the finished tape sound records are coiled up. A vat or tank of liquid parafl'in or similar substance is indicated by 8. Similar tanks containing acid and. water, respectively, are indicated by i] and it. A pipe ll provides a blast of cold air. The magnet t is connected in a circuit in which the sound currents to be recorded are flowing. For convenience the sound may first be recorded in the usual way on a disc or film record. Any well known type of electrical pick up device may then be used and the magnet 5 is connected in the output circuit of the final amplifying stage. The magnet 5 has a, pivoted armature 5 which carries a stylus i, in contact with the tape.

In setting up the apparatus the tape 3 is threaded under and over the rollers shown and through the dryer H, but since the first portion to come through will not be separated into two halves it cannot at once be attached to the reels M and it. The tap-e is therefore pulled through by hand for a short time in order to get the process started. As the tape passes through tank 8 it receives a coating of parafiin, which is cooled and hardened by the air blast. The coated tape next passes under the stylus i which traces a line down the center, exposing the surface of the metal along the line. The tape then passes into the acid bath in tank 9. The acid dissolves the metal tape away where the surface is exposed thus separating it into two halves. From the acid bath the two halves of the tape pass through the water tank Ml, where they are washed clean of acid, and. through the dryer M, in which a current of hot air is maintained.

As soon as the tape begins to come through in 7 two separate parts the end may be cut oh and the two parts are then attached to the reels" aoeaoii the split tape passes before being reeled up may be'power driven so as to pull the tape through the apparatus at a constant speed. The sound apparatus may now be turned on. As magnet 6 becomes active the stylus i will produce a wavy line on the tape in accordance with the sound record, similar to the line shown in Fig. 8. As a result the tape will be split in two parts along a variable line, producing two sound record tapes which are reeled up on reels M and 65.

It will be understood that Fig. 5 is a diagrammatic illustration of the process described, and the parts may be suitably modified in practice. For instance, the length of the acid bath 9 must be sufiicient to give the correct number of immersions to sever the tape. The number required depends on the thickness of tape used, the solution used, and the speed of the tape through the apparatus. In any particular case the correct number should befound by trial before the actual production of records begins. The acid bath may be constructed with the maximum number of rolls, and then one or more may be by passed in order to limit the immersions to the requisite number.

Other'parts of the apparatus may likewise be suitably modified. The reels M and should of course be provided with suitable take up devices to maintain tension on the tape. Devices suitable for this purpose are known and hence are not shown. However, I have designed a novel form of take up device which is shown in connection with Fig. 2 and which will shortly be described. This device may also be used with 35 reels M and i5.

Referring now to Fig. l, which illustrates a process of printing sound records on paper or similar tape, the reference character indicates a reel on which the master sound record is wound. This sound record may be metallic tape record such as is shown in Fig. 7. In Fig. 1 the master sound record, partly unwound from reel 3@, is indicated by 32. M is another reel to which the sound record tape 32 is transferred in the printing process. As shown, the tape 32 passes from reel it over an idler roller 3i, and thence through the inking apparatus 33. From this point the tape passes through the printing rollers 36 and 35. A duplicate inking apparatus 3 and another pair of printing rollers 54 and 135 are shown, as the process contemplates the printing of a plurality of sound records simultaneously. From the last pair of printing rollers the tape 32 passes over the power driven roller 50, and thence to the take up reel M. A motor for driving roller W by means of a belt is indicated at 39. The printing rollers 35 and (i5 are also preferably positively driven, and belts are shown for accomplishing this.

The reel 36 holds a supply of paper tape on which the sound record is to be printed. This tape 39 passes over the printing roller 35 underneath the tape 32 and on to a take up reel M. The reel 36 likewise holds a supply of paper tape. This tape 38 passes over the printing roller 55 and is wound up on reel ii. In the operation of the apparatus the roller Ell and the printing rollers 45 and 35 are driven at the proper speed and pull the metal tape 32 through the printing apparatus. Thus the tape 32 is gradually transferred from reel 3m to reel il. Considering the left hand printing unit more in detail, the tape 32 first passes through the inking rollers in the inking apparatus 33, where it receives acoating of ink on the lower side.

The tape next passes through the printing rollers 34 and 35 where it comes in contact with the paper tape 38. The rollers press the two tapes together progressively, as tape 38 is also moving, being unwound from reel 36 and rewound on reel 31. Thus an impression of the tape 32 is printed on tape 38. As the tape 32 moves along it receives a new coating of ink at 43, which is transferred to the paper tape 48 where the two tapes are pressed into contact'with each other by printing rollers 44 and 45.

The paper tapes 38 and 48 thus have printed on them exact'impressions of the master sound record tape 32. They can be used in known photo-electric reproducers of standard type to reproduce audibly the original sounds. Fig. 9 shows a small section of a' printed sound record made by the process just described. The black area is the ink impression of the'mas'ter sound record.

Reference will now be made to Fig; 2 in order to describe the stencilling process of manufacturing sound records which is therein illustrated.

The reference character 58 indicates a reel which holds a master sound record tape 58 which may be similar to the one shown in Fig. 7..

The tape 58 is shown partly transferred to the reel 51, on which it is gradually wound up. Intervening between the reels 58 and 51 is a large roller 53, over which the tape 58 is guided by smaller rollers 5|, 52, 54 and 56. The roller 56 may be positively driven by any suitable means such as a motor 55, andthus serves also to drive the tape. It will be seen therefore that the tape 58 passes oil thereel 58 and over the roller 5|, from which point it passes successively under roller 52, over the large roller 53, and under the roller 54. From roller 54 the tape 58 passes over the driven roller 56 and then on to the reel 51. The rollers 52 and 54 have the special function of holding the tape in contact with the roller 53 for a considerable angular distance around its periphery. The purpose of this is to maintain close-contact with the paper tape 6| during the stencilling operation and to provide for enough friction to effectively drive roller 53. Of course a separate positive drive for roller 53 can be provided but this is not generally necessary.

As stated hereinbefore the metal tape 58 is wound up on reel 51 as fast as it is pulled off from reel 58. This is accomplished by a take up apparatus which may now be described briefly; reference being had to Figs=2 and 4. The member 1| may conveniently be pivoted on the shaft 18 which carries the driving roller 56, and at its lower forked end it carries a small roller 11 which rests against the wound up tape on reel 51. Member 1! also has attached to it a bracket member 12 which passes around one edge of reel 51 and at its end carries a short shaft. On this shaft there is rotatably mounted a driving unit comprising a pulley l4 and a friction wheel 15, the latter of which bears against the side of reel 51 as shown. Outside of the driving roller 55 the shaft 18 carries a small pulley 13. The pulley 13 is connected with the pulley 14 by a belt 18. With the apparatus in operation, the tape 58 is fed through to reel 51 by the driving roller 56. At the same time, the pulley 13 is rotating and drives the friction wheel 15 by means of belt 16 and pulley 14. The relative size of pulleys 13 and 14 should be such that the reel 51 tries to wind up the tape 58 a trifle faster than it is fed forward by driving roller 56, thus maintaining the tape taut. The friction wheel 15 has a light contact with the reel 51. and slips 2. little. As the tape 58 is reeled up the diameter of the wound up body of tape on reel 51 increases which makes it necessary to gradually slow down the speed of reel 51. This is taken care of by the arrangement including roller 11, resting on the wound up tape. As the tape accumulates on reel 51, roller 11 moves the end of arm 1! outward and causes the friction wheel 15 to move toward the outer edge of reel 51, thus slowing down the speed of reel.

The take up device just described is suitable for use in connection with other reels shown in the drawings, but has been shown at only the one point in order to avoid unnecessary complication. For instance, a take up reel of this type could Y be used in place of reel 4|, Fig. 1', or in place of roller 53, and thence on to the take up reel 84.

The stencilling apparatus is shown in Fig. 2

' just, above the roller 53, ,and is also shown in section in Fig. 3. The apparatus is enclosed in a container 80, at the bottom of which is a. supply of stencilling liquid as indicated in Fig. 3. The stencilling is performed by means of a fine spray of liquid produced by an aspirator which includes the-air pipe 8| and the tube 82. That portion of the container 88 which extends over the roller 53 has a narrow slit therein, toward which the spray is directed.

The process will doubtless be sufilciently understood from the description of the apparatus employed, but may nevertheless be described briefly. As the master record tape 58 is drawn through the apparatus it rotates the roller 53 which drives the paper tape 6|. The two tapes are in close contact as they pass over roller 53. As the tapes pass under the slit in container 88 they receive the spray of stencilling liquids or that portion of it which goes through the slit, and thereby a substantial part of the surface of the paper tape which is not covered up by the master tape is given a coating of the stencilling liquid. The width of the slit is preferably such that the spray does not'extend quite to the edge of the tape 8|, so as not to get any on the roller 53.

The two tapes separate underneath roller 54 and the "paper tape 8'1 proceeds down through the dryer 62, after which it is wound up on reel 64. If desired the master tape 58 may be passed through a suitable arrangement for washing ofl. or otherwiseremoving the liquid from its surface before it is wound up. A, section of the complete stencilled paper tape sound record is shown in Fig. 10. In Fig: 18 the black area is that portion of the tape which is coated with the stencilling liquid while the upper light area is the portion which was covered up by the master tape. The master tape intercepts a variable amount of the spray and thus causes the stencilled band to vary in width in accordance with the sound record.

The amount of conversation, music or other sounds which can be recorded on a given length of metal tape depends on the. speed at which the tape moves during the recording process.

In order to record the maximum amount the tape is therefore moved as slow as possible consistent with other factors. If the recording process is carried out at a fairly high speed the successive variations in width which occur in the resulting tape record will be relatively far apart and will be more or less rounded ofi, which makes a tape record which is not easily damaged. In Fig. 7, for instance, it will be seen that the serrations on the lower edge of the tape are substantial and not especially liable to be broken off. In making a sound record tape like Fig. 7, the recording process is carried out at a fairly high speed. It would be possible to slow the speed of recording down somewhat, but as the speed is reduced the serrations would come closer together, so that before long a point would be reached beyond which no further reduction in speed could take place without producing a record with serrations so fine that they would be easily damaged in handling the tape during the printing or stencilling process.

In order to increasethe length of the sound recorded which can be carried by a metal tape a somewhat different form of tape may be used, as will be explained in connection with Figs. 11 and 11A.

The metal tape may be bi-metallic, that is, composed of layers of two different metals. The process is facilitated if one metal, the one which forms the rear layer, is less susceptible to the etching acid than the other metal. The process of recording sound on such a tape is similar to the photographic process described, except that the tape may be moved at a much slower speed during exposure to light. After exposure, the

etching process is carried far enough so that the upper layer of metal is removed where it has not been exposed, the process being stopped as soon as the rear layer of less susceptible metal is reached. The rear layer, being left intact, forms a backing for the irregular upper layer in which the sound record has been etched.

Fig. 11 shows a section of a completed bimetallic tape sound record made according to the foregoing, and 12 is an end view. 'In

' Fig. 11 the unshaded area is the upper layer of metal in which the sound record is formed, while the shaded area is that portion of the rear layer of metal from which the upper layer has been removed. Both layers can be seen also in Fig. 11A. It will be observed that the serrationsv are much closer together than in Fig. 7, but this is not particularly objectionable from a mechanical standpoint, as it would be in a tape record like Fig. 7, because the fine points are protected by the rear layer of metal.

It will be clear that a record of thistype can be made from a plain single layer metal tape,

which, however, should be thick enough so that the etching process can be stopped after the metal has been removed to a depth of about .005 inch, leaving a sufllcient amount of metal to give the required support and protection. The n of a bimetallic tape merely renders the manuffdtnr: of the record somewhat easier.

Records f the type shown in Fig. 11 are of course not adapted to the stencilling process shown in Fig. 2. They are intended for use in the printing process which has been described in connection with Fig. 1.

Referring now to Fig. 12, this drawing shows a diagrammatic plan view of an endless single surface tape of paper or other material on which a sound record may be printed or stencilled by one of the processes hereinbefore described, or by any other suitable process. In view of -the small scale of the drawing no attempt has been made to show an actual sound record, but the record is indicated by the line 92. It may be stated at the outset that the object in view in designing this particular form of tape sound record is to produce a tape bearing a continuous sound record occupying parallel paths on both sides of the tape, thus providing for recording 10 the maximum amount of sound on a given amount of tape.

The tape will be many yards in length in practice, and will be coiled up in a roll, as will be explained subsequently. The short tape shown 16 in Fig. 12 can conveniently be made use of in explaining the principle involved. This tape has been shown flattened out or bent over at equally spaced points 85, 86 and 81!, formingthree equal sections 88, 89, and 90. Thus the path of the 20 record represented by line 92 can readily be traced.

The record 92 may be assumed to start at point 9t on the upper surface ct section 88. From point 90, it may be traced downward in 5 the direction of the arrow and around bend 86, along the under side of section 89, as shown by the dotted line, around bend 8?, upper surface of section 98, around bend 85 on the inside, lower surface of section til, around bend 86 (inside), upper surface of section 89, around bend 81 (inside), lower surface of section 90, and around theupper bend 85 to the upper surface of section 88, where it passes the starting point 9|. It will be seen from the foregoing that the line 92 passes around the tape twice lengthwise before returning to the vicinity of point 9|, where it started. In thus traversing the length of tape the line appeared on both sides of each section thereof.

It will be understood that the record represented by line 92 works gradually to the right, considering section 88, so that when it finally appears near point 0| after making a double circuit of the tape, it will be displaced sufilciently 45 so that it can continue on around without being superimposed on itself. The amount of displacement required depends on the'width of tape required for one sound track. Satisfactory records can be made of the variable width type which 5 are somewhat less than 3 of an inch in width.

A sound track of this width can pass a considerable number of times around the tape before it is filled up. If the tape is two inches wide, there may be eight parallel sound tracks on each side of the tape at any particular point. This means that the continuous sound track will pass sixteen times around the tape. It will be appreciatedthat a very large amount of speech .or music can be recorded on a moderate length of a tape.

A suitable reel for handling an endless double surface tape such as has just been described is shown in Figs. 13 and 14. These drawings are more or less in diagrammatic form, although they show clearly the construction of the reel and the principle involved in its operation.

The various parts of the reelare supported on a base member I0I, which may be of any suitable form. On the base IOI is mounted adisc 7 I02, which is pivoted at I03 so as to rotate freely. On opposite sides of .the disc I02 there are two upright members I04 and. I05 which are firmly attached to the base IOI. These members can be seen clearly in the perspective drawing Fig. (I

14. The member I05 does not appear in Fig. 13, having been omitted along with part of member I 06 in order to avoid obscuring other parts. The member I06 extends across between the upper ends of member I04 and I05 to which it is secured. On the lower side of cross member I06 is secured a fixed disc or plate I01.

The disc I01 carries on the lower side thereof a circular row of rollers IIO. There may be twelve or more of these rollers equally spaced around the circumference of a circle. Each roller may be mounted on a stud which is screw threaded into the disc I01 as indicated in the,

case of the left hand roller I I0 in Fig. 14. These" rollers extend downward toward the rotatable disc I02 but do not quite reach it, sufilcient space being allowed so that the rotation of disc I02 will not be interfered with.

Inside the circle described by the rollers I I0 is mounted a member II2. This member H2 is a round polished rod and is firmly secured to the disc I01 at its upper end. It lies in a plane substantially parallel to member I06 and the end points downward at an angle of forty-five degrees. As in the case with the rollers IIO, the lower end of member II2 should clear the disc I02.

As will be seen clearly from the drawings the main portion of the tape H5 is formed in a roll and is supported on the rotatable disc I02. The inside layer of tape fits loosely around the rollers IIO. At a point just in front of the left hand roller IIO, see Fig. 14, the tape leaves the roll and extends between this roller and the next one to it in a counter clockwise direction, pass;- ing toward the center. The tape then passes underand around the member H2 and extends upward through. a slot H9 in the disc I01 and the cross member I06.

Certain rollers are shown in the drawings for the purpose of drawing the tape off the reel and for guiding -it back on. Referring particularly to Fig. 13, the rollers H6 and Ill are mounted above the reel as shown. The roller H6, or roller II1, may be driven from some suitable source of power. The tape II5 passes over roller II6, then over a roller H8, and thence back on to .the reel. Roller I I1 preferably is pressed against roller II6 by spring tension or other means in order to avoid any possibility of the tape slipping on roller II6.

In the operation of the reel, the rotation of roller II6 moves the tape H5 in the direction shown by the arrow. As can be seen more clearly from Fig. 14, the tape is drawn off from the center of the roll, around roller IIO, around the rod II2, where it changes its direction, and upward through the slit H0 toward roller II6. This operation causes a rotation of the main body of the roll which is supported on the disc I02. The roll and disc therefore rotate, in a counter clockwise direction. The rotation of the main roll winds up the tape as it leaves roller II8. This produces some tension in the tape which causes the main body of the roll to gradually collapse by slipping of the layers. The construction is such as to eliminate friction-as much as possible and the tape is pulled off easily. There is no tendency to bind around the rollers H0 or between the layers of the main body of tape because the tape is being drawn off from the inside of the roll, which tends to constantly increase the diameter of the inner layer. This tendency is just overcome by the tension produced by winding up the tape on the outside, which causes the layers to slip on one another and maintain the size of the roll constant.

In order to permit of readily changing rolls the cross member I06 is preferably removably secured to the upright members I04 and I05 so that the assembly comprising cross member I06, disc I01, and rollers IIO can be lifted off. A slot I20, Fig. 13, is also cut in disc I01, connecting with slot I I9, so as to permit the tape to be inserted or removed.

A reel of the type just described can be used in manufacturing printed or stencilled paper tape records of the endless single surface type such as is shown in Fig. 12. The process illustrated in Fig. l; or the stencilling process shown in Fig. 2 may be used. In Fig. l, for instance, the tape 38 and reels 36 and 31 may be replaced by tape H5 and the reel shown in Fig; 13, to-

gether with rollers H6, H1, and H8, that section of I the tape II5 which extends between rollers II6 and'II8 being passed over roller 35. Or rollers H6 and H1 could be omitted, being replaced by roller 35. It will be understood that in an assembly of this kind the reel and associated rollers for guiding the tape 'must be mounted on a base or platform which can be traversed in a direction perpendicular to the master tape, thereby providing for printing a continuous record on the tape in parallel paths. Apparatus for providing a slow movement such as is required in this case is well known in this art and need not be described herein.

Having described my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims: 7

1. The process of copying a master tape sound record of the variable width type, on tape of paper or similar material which consists in producing a spray of stencilling liquid, in passing the paper tape through the spray, in simultaneously passing the master tape through the spray in contact with the paper tape on the side thereof against which the spray is directed, and in restricting the cross section of said spray to a point adjacent said tapes.

2. In combination, a sound record comprising a master tape of variable width, means for bringing successive portions of one side of said tape in contact with corresponding portions of a second tape, with their fiat sides together, means for directing a spray of coating material against a portion of the master tape and an exposed portion of said second tape while the tapes are in contact, and means for blocking the spray from the remaining portion of said master tape and from a part of the exposed portion of said second tape.

3. In combination, a master tape having-a sound record formed thereon, meansfor producing a spray of stencilling liquid, means for progressively passing successi e portions of a second tape under said spray, means for simultaneously intercepting portions of said spray with successive portions of said master tape, and means for intercepting all except a predetermined limited portion of said spray before it reaches said master tape.

4. The process of making a sound record on a paper tape from a master tape sound record of the variable width type, which consists in directing a spray of stencilling liquid toward the tapes where they are pressed together, in intercepting the spray on one side at a point above the master tape, and in intercepting the spray on the other side at a point above continuously exposed portions of the paper tape, whereby a record is produced on the paper tape having a straight edge on one side and an irregular edge on the other side as determined by the width of the master tape.

5. The process of making a sound record on a paper tape from a master tape of the variable width type, which consists in moving said tapes simultaneously with the master tape superimposed on the paper tape and in contact therewith, in adjusting the moving tapes laterally so that a portion of the paper tape is exposed along the variable edge of the master tape where the tapes are in contact, in directing a spray of stencilling liquid toward the tapes from the master tape side, and in confining said spray where it approaches the master tape to a width which leaves a part of the master tape and a part of the paper tape uncoated while depositing along the overlapping variable edge of the master tape a coating which reproduces on the paper tape all the width variations in the master tape.

6. In combination, a sound record comprising a master tape varying in Width and equal in length-to a section of paper tape on which the record is to be reproduced, means for moving said tapes uniformly and uninterruptedly and at the same rate, means for forming a semicircular loop in the moving tapes, means for maintaining said tapes out of contact except at the said loop and for pressing them together at that point, and means including said master tape for applying to said paper tape as themaster tape is pressed against it a continous coating having variations in width corresponding to the variations in width of the master 2o tape.

OLD J. MCCREARY.

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