US1340360A - Tracking device - Google Patents

Description

0. H. ARNO. TRACKING DEVICE. APPLICATION mm mm 19.1911.

Patented May 18, 1920.

2 SHEETS8HEET 1- Tag/E75 0. H. ARNO.

TRACKING DEVICE.

APPLICATION men JULY 19.19:].

m 99 H 9F. VL an m m W n m P.

UNITED STATES PATENT OFFICE.

OLIVER H. ARNO, 015

BOSTON, MASSACHUSETTS, sssmnon T0 GEORGE 0. G. COALE, TRUSTEE, or BOSTON, MASSACHUSETTS.

TRACKING DEVICE.

Specification of Letters Patent.

Patented May 18, 1920.

Application filed July 19, 1917. Serial No. 181,617.

To all whom it m (11 concern Be it known that I, OLIVER H. Anne, of Boston, in the county of Suffolk and State of Massachusetts, a citizen of the United States, have invented a new and useful 1m provement in Tracking Devices, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forrnin a part of this specification, in explaining its nature.

The present invention relates to that type of automatic devices for causing a perforated music sheet to run correctly with relation to a tracker-board. The device is especially adapted to be used in connection with the perforated sheet of a musical instrument.

The essential object of my invention is to provide a device which will automatically maintain proper relationship between the sheet and the tracker-board under all operating conditions, especially when the width of the sheet varies due to atmospheric conditions or otherwise.

My invention can best be seen and understood by reference to the drawings in which there is shown an embodiment thereof applied to a piano player, only such portion of the instrument being shown as is necessary to a proper understanding of the invention, and in which Figure l is a view in front elevation.

Fig. 2 is a section on the line 2-2 of Fig. 1.

Fig. 3 Fig. 1.

Figs. l and 5 are plans of details of construction to which special reference will later be made.

Referring to the drawings is a section on the line 33 of 1 represents the spool box or casing in which are arran ed the usual trackenboard 0 0 52. music spool b carrying the perforated sheet. and tales-up spool a. which is actuated for drawing the perforated sheet from off" the music spool over the face of the trackerboa rd.

The spools are mounted in the usual man ner to be movable laterally in either direction. to the right or left. for positioning the perforated sheet in proper relation to the openings in the tracker-boa rd. In other words. the music spool is supported by trunnions 5 and 6, respectively, of which the trunnion 5 is slidalt-le within a bearing T on the left side of the spool box and is backed by a spring 8, which tends to force the trunnion and spool supported by it constantly toward the opposite side of the box. The trunnion 6 is mounted to turn, and be slidable, within a bearing 7 on the right side of the spool box. The take-up roll is mounted upon trunnions 9 and 10', respectively, which turn, and are slidable. within bearings 11 on the opposite sides of the spool box.

Provision is made for laterally positioning the spools and sheet carried by them with relation to the tracker-board as follows: Secured to the base of the spool box or casing or other suitable base of support is a pneumatic 12 having a movable side or member 13. The pneumatic is maintained normally expanded by a spring ll. The pneumatic is contracted by suction of air from the wind chest (not shown) through a connecting pipe 15 and other connections later to be referred to. Secured to the movable side of the pneumatic is a link 16, which connects with an arm 17 fixed to a roller 18. This roller is arranged in front of the trunnions 6 and 10, respectively, of the music and take-up spools, and turns between the brackets 19 secured to the side of the spool box or casing. Fixed also to the roller 18 are arms 20 projecting therefrom in the direction of the trunnions 6 and 10, and entering, respectively, the grooves in annularly-grooved collars E21 arranged upon these respective trunnions. 'ith the parts thus arranged, both spools and perforated sheet carried by them will be moved laterally to the left over the tracker-board as the movable side of the pneumatic is drawn inwardly upon the con traction of the pneumatic, and is moved in a. reverse direction, to the right. as the pneumatic is. allowed to expand by the spring, the movement being limited by the full expension of the pneumatic.

According to the operation of the device, as will later be more fully explained, the spools and perforated sheet are initially moved to the left by the contraction of the pneumatic in order to position the perforated sheet to track right in relation to the openings in the tracker-board. \Vhen thus positioned, both spools and sheet are capable of freedom of movement in either direction, to the right or to the left. The amount of contraction of the pneumatic for moving the spools and sheet to a correct position for the pipe connects. Connecting also with this box is a pipe 24, which connects with a suction box 25, and connecting with the suction box 25 is a pipe 26 leading directly to the wind chest. By prearrangement the passage from the pipe 24 into the suction box 23 consists of a relatively small vent 27. There opens, also, into the suction box 23 a vent 28 from the atmosphere. The vent 28 is formed through a .duct 29 secured to, and projecting outwardly from, the suction box 23, and the mouth or opening to the atmosphere at the end of the duct is controlled by a valve 30. The vent 28 is made considerably larger than the vent 27. Accordingly, when the valve is moved to a position away from the end of the duct to leave the vent 28 fully open, the vacuum effect induced in the pneumatic by suction from the wind chest tending to contract the pneumatic, will become broken, and the pneumatic will tend to expand, the side or member 13 thereof being moved outwardly by the action of the spring 1 4. \Vhen, however, the valve 30 is engaging the mouth of the duct, closing the vent 28, the suction of air induced by the wind chest will tend to contract the pneumatic and the movable side thereof will be moved inwardly. hen the pneumatic is partially contracted any further contraction of it will immediately cease and the movable side thereof remain in substantially the position to which it has been moved when the valve 30 is displaced into a position which will leave an opening through the vent 28 to the atmosphere substantially equal in area to the area provided by the vent 27. The valve 30, it will be observed, is simply a block, generally rectangular in form having preferably a leather pad or face 32 on the side which fits against the mouth of the duct 29 forming a seat for it. It will be also be observed that the end of the duct 29, against which the valve has bearing, is flattened and presents a narrow elongated opening, for, as will later be explained, the valve 30 in the operation of the device is adapted to turn around the end of the duct 29, and it is desirable that the valve properly control the vent or opening through the duct irrespective of the turned or changed position of the valve.

Accordingly, the end of the duct 29 is flattened'in order that the valve may turn readily on or around the same.

The valve 30 rests upon a board 33 fixed to the base of the spool box and turns there on. For the purpose of otherwise assisting in the support of the valve and for maintaining it always in proper position to control the opening through the duct 29, whatever the turned position of the valve may be, there projects from the under side of the valve, or that side bearing against the board 33, at about the center thereof, a lug 34 having in it a slot 35. Entering this slot is a pin 36 extending from the board 33 exactly opposite the center of the mouth of the duct. Thus supported and retained, the valve will turn on the pin 36, the slot 35 in the lug permitting of the valve occupying either an open or c osed position with relation to the duct 29, whatever the turned position of the valve may be.

The open or closed position of the valve 30 is controlled automatically by the perforated sheet depending upon the laterallymoved position of the sheet, and the control is effected from both edges of the sheet. Such control is effected as follows: Arranged to have bearing against the opposite edges of the perforated sheet are presser fingers 40 and 41, respectively. These fingers are borne by arms 42 extending from rollers 43, which turn in bearings 44 and 45, respectively, on the spool box. The rollers 43 are arranged at opposite sides of the spool box beyond the edges of the perforated sheet and out of the plane of the sheet, the arms 42 extending angularly therefrom so that by the turning of the rollers the fingers 40, 41, carried by the arms 42, may be moved into and out of engagement with the edges of the sheet, and on the other hand the rollers will be turnedby lateral movement of the perforated sheet, or by movement of the edges thereof, in the event of expansion or contraction of the sheet, when the fingers are in engagement therewith.

The fingers 40 and 41 are restricted in movement by the fore and aft space-d edges, 47 and 48, respectively, of stops 49 secured to the sides of the spool box and between which edges of the stops the fingers are movable. The limitation in the movement of the fingers limits, also, the extent to which the rollers 43 are capable of turnlng.

Carried by the rollers 43 are arms 50 and 51, respectively. These arms extend from the rollers at points in substantial horizontal alinement with the valve 30, as the parts are generally arranged, and the extension of the arms is such that as the rollers 43 are turned in one direction or the other, incident to the movement of the fingers 40, 41, the arms will be moved in a general direction towardor away from the valve 30. Pivotally connecting with the end of the arm 50 1s a link 52'which pivotally connects, by an attaching eye 53, with the top end of the valve 30. Pivotally connecting with the end of the arm 51 is a link 54:, which is pivotally secured by an attaching e e to the bottom end of the valve 30. earing against the outer sides of the arms 50, 51 are springs 56 suitably secured, and which operate by their tension to press the arms 50, 51 inwardy and thereby tend to maintain the fingers 40, 41 in engagement with the edges of the sheet or with the inner edges 47 of the finger stops, were the sheet elimi nated.

The bearing of the spring 56 against the arms 50, 51 tends, also, through the connecting links 52, 54: to turn the valve 30 around the end of the duct 29, as the tendency is to move the bottom end of the valve 30 to the left and the top end of the valve to the right. Such cooperative action between the springs 56 and the valve is availed of to control the position of the fingers 40, 41 in relation to the edges of the paper; in other words, preventing the springs 56 from moving the fingers inwardly to bear against the edges of the paper when the instrument is out of play ing action, and especially during the rewinding of the sheet, but permitting of the fingers instantly drawing into engagement with the edges of the sheet, and maintaining them in such position, when the playing action commences and durin the continuance thereof. This effect is o t ained as follows:-

Carried by the board 33 is a pneumatic 58 having a movable side 59. The pneumatic is maintained normally expanded by a spring 60, which is of greater tensional strength than that of the combined springs 56. The contraction of the pneumatic is effected from the wind chest by a pipe 61 connecting with the suction box 25. loosely secured to the movable side 59 of the pneumatic is a wire 62 having in it a bend or shoulder 63, and the free end of which wire extends through an eye 64 secured to the outer side of the valve 30. The location of the parts, and especially of the wire 62, and the location of the shoulder on it is such that when the pneumatic 58 is in its normal expansion, the shoulder 63 upon the wire having engagement with the eye 64, on the valve, will prevent any turning of the valve by the action of the springs 56, and accordingly, the action of these springs being thus restricted, they cannot move the fingers 40,41 into en agement with-the edges of the sheet and accordingly, the fingers will be then maintained in a position away from the edges of the sheet and bearing against the outer edges 48 of the respective finger stops. When, however, the pneumatic 58 is contracted, the valve 30 will then no longer be restricted by the wire 62 and will be capable of being moved freely, as above described, around the end of the duct 29 by the springs 56, the action of which now unimpeded, will throw the fingers 40, 41 into engagement with the edges of the sheet or into engagement with the inner edges 47 of the finger stops, were the sheet to be eliminated.

In order to obtain the general operative effect presently to be described the parts are proportioned and arranged to bear a definite relation to one another. Especially is this true of the disposition of the valve 30 in relation to the end of the duct. This valve is so arranged that when the pneumatic 12 is fully expanded and the spools are consequently occupying a position displaced toward the right side of the spool box, the valve 30 will then be occupying a closed position with relation to the duct 29 and vent to the atmosphere through the same. For positioning the valve 30 one important factor consists in that the valve,

the suction box and the duct 29 projecting from the box are located upon the board 33, which is adjustably secured to the base of the spool box by means of attaching screws 65, which pass through slots 66 permitting of the adjustment. Inasmuch as the suction box 23 and duct 29 attached to it are fixed to the board and inasmuch as the valve is but loosely secured to the board by means of the pin .36 and the position thereof is otherwise governed by means of the connecting links 52, 54, the valve can accordingly be positioned in proper relation to the end of the duct by the lateral adjustment of the board As will later be more fully explained, the valve 30 in the operation of the device will be operated to have either a closed, partially open or open position in relation to the vent 28 through the duct 29, and such position of the valve, whether open or closed, will be maintained even though the valve may be turned slightly on or around the end of the duct. In order to meet such requirements and enable the valve to function properly according to the prescribed conditions, the duct 29 is made out of very thin tubing and its flattened end is in practice slightly over of an inch in thickness, leaving the vent through the end of the duct a mere slit. The end of the tube is also rounded. As previously described, also, the valve 30 is preferably provided with a leather pad or face. It should also be understood that any turning movement of the valve 30 on or around the end of the duct is very slight, all of which, considering especially the fact that the valve is turning 011 a mere edge, enables it to maintain its position with regard to the vent or opening whatever the turned position of the valve may be, any change being so inappreciable as not to affect the operation of movement, and

the device, and in any event will be compensated for.

The operation of the device is as follows It will be assumed that the spools are in place and the sheet carried by the music spool is connected to the take-up spool ready for unwinding. The spools and sheet will then be occupying a position displaced by the pneumatic l2 and action of spring 8 toward the right side of the spool box. This position is defined, as before pointed out, by the full expansion of the pneumatic. The pneumatic :38 will, also, be fully expanded and will accordingly through the wire 62 hold the valve 30 from being turned. The holding of the valve will prevent the springs 56 from moving the fingers 40, i1 into engagement with the edges of the sheet, and the fingers will occupy a position in engagement with the outer edges -18 of the finger stops 49. The valve 30 will be occupying a closed position in relation to the end of the duct 29 and vent 28 through it to the atmosphere. By prearrangement, also, the perfoiations in the music sheet will not track right with the openings in the tracker-board and will occupy a displaced position to the right thereof, depending upon the initial displacement of the spools.

The instrument being set into operation,-

comnmnication is now immediately had be.- tween the wind chest and the respective pneumatics 12 and 58. The pneumatic 58 will be immediately contracted, and the valve 30, being then no longer held by the wire 62 secured to its movable side, will no longer restrain the action of the springs 56, which will then operate by their hearing against the arms 50 to turn the spindles 43 and, through the arms l2, move the fingers 40. ll into engagement with the opposite edges of the sheet. The bearing of the springs 56 against the arms 50, 51 will operate to throw these arms both inwardly, with the effect of turning the valve 30 upwardly and around the end of the duct 29, the valve still continuing, however, to occupy a closed position with relation to the end of the duct and vent 28 through it to the atmosphere. During the contraction of the pneumatic 58 the contraction of the pneumatic 12 will continue and thereupon will operate through the connecting mechanism to move the spools and perforated sheet toward the left side of the music box. This movement continues until the perforations in the sheet are in proper alinement with the openings in the. tracker-board, and then ceases. During this movement the fingers 40, 41 will continue to bear against the opposite edges of the sheet. the finger 40 being pressed back by the left edge of the sheet during the the finger 41 following the right edge of the sheet, both fingers, in other words, moving in the same direction. It is this movement of the fingers which positions the sheet in proper relation to. the openings in the tracker-board for the fingers will operate by the movement, through the spindles 43, arms 50, 51 and links 52, 54, respectively, to move the valve 30 away from its seat into an open position with relation to the duct 29 and vent 28 through it to the atmosphere. That is, following and incident to the movement of the fingers a pull'action will be exerted upon the link 52 and a push action upon the link 54 with the efiect of moving the valve 30 away from its seat on the end of the duct. The parts are so proportioned that the valve 30 will be moved into an open position, where it will leave an opening from the atmosphere through the duct 29 or vent 28 substantially equal in area to the vent 27 in theconnection between the wind chest and pneumatic 12, when the sheet has been moved to a position where the perforations in the sheet will track right with the openings in the tracker-board. Thereupon, further contraction of the pneumatic 12 will cease, but the contraction already attained. will be maintained for maintaining the sheet in the position to which it has been moved and until further displacement thereof occurs. In the event of displacement, assuming that the sheet becomes displaced to the right so that the perforations will not track right in relation to the openings in the tracker-board, thereupon the movement of the fingers following the opposite edges of the sheet will provide an effect whereby the valve 30 will be moved into a closed position with relation to the duct 29 or vent 28 through it, and consequently the pneumatic 12 will be further contracted returning the sheet to its proper position. ()11 the other hand, if the sheet should be displaced too far to the left on the tracker-board, then the fingers will be moved to a position where the action will tend to further open the valve 30 in relation to the duct 29 or vent 28 through it to the atmosphere, permitting the pneumatic 12 to expand and thereupon returning the sheet to its proper position. In point of fact, in the actual operation of they device, after the sheet has once been positioned, the actions above referred to are not pronounced ac.- tions in the sense of being easily observable, but occasion simply a slight flutter in the operating parts in case of thedisplacement ot the sheet. 7 V

Apart fromfthe operation above referred to, the effectiveness of the device is further seen in that any contraction or expansion of the sheet, due to atmospheric conditions or otherwise, will be negligible and has no effect upon the operation of .the'device forproperly positioning the sheet with relation to the openings in the tracker-board. The reason for this is that the arrangement of the parts is such that the valve 30 will be moved to an open or closed position only as the sheet is moved laterally in one direction or the other as a whole causing displacement of the fingers 40, 41 in the same direction.

111 the event of expansion or contraction of the sheet, inasmuch as the sheet expands or contracts from its center, the edges thereof will be moved relatively outwardly or inwardly in reverse directions. The fingers 40, 41, following such movement or displacement of the edges, will have a corresponding outward or inward movement in reverse directions, and this reverse movement of the fingers through the connecting mechanism will not operate to change the open or closed position of the valve in relation to the duct 29 or vent 28 through it to the atmosphere, but will simply operate to turn the valve pivotally around the end of the duct, its open or closed position, whichever it may be, continuing to be maintained whatever the turned position of the valve may be.

After the playing action has been discontinued, communication between the wind chest and pneumatic is shut off and the pneumatic 58 will be allowed to expand, and thereupon, operate through the connecting mechanism to throw the fingers 40, 41 outwardly away from the edges of the sheet, permitting of its being rewound from the take-up spool back onto the music spool. At the same time the pneumatic 12 will be allowed to expand and by its expansion move, or assist in moving, the spools and sheet back to their original positions.

Having thus fully described my invention, claim and desire to secure by Letters Patent of the United States 1. The combination of a tracker-board having a series of openings in it, means for carrying a perforated sheet whereb it may be drawn over said board, means or moving the sheet sidewise for positioning it in relation to the openings in the tracker-board and comprising in part a motor, and means for, governing said motor to position said sheet in proper relation to the openings in the tracker-board and to restore said sheet in the event of its displacement, said lastnamed means comprising in part independently-movable, disconnected, sheet-contacting members yieldingly maintained to have engagement with the opposite side edges of the sheet and other associated parts exert ing no influence upon said motor to change the position of said sheet in the eventof its expansion or contraction or. upon the movement of the edges of the sheet outwardly or inwardly in reverse directions, but operating to influence said motor to position said sheet in proper relation to the tracker-board and to restore said sheet to a proper position in the event of its displacement by the conjoint movement of said sheet-contacting members upon the sidewise displacement of said sheet as a whole irrespective of the expansion or contraction thereof.

2. The combination of a tracker-board having a series of openings in it, means for carrying a perforated sheet whereb it may be drawn over said board, means fin moving the sheet sidewise for positioning it in relation to the openings in the tracker-board and comprising in part a motor, and means for governing said motor to position said sheet in proper relation to the openings in the tracker-board and to restore said sheet in the event of its displacement, said last named means comprising in part independently-movable, disconnected, sheet-contacting members yieldingly maintained to have engagement with the opposite edges of the sheet and other associated parts operating to influence said motor to position said sheet in proper relation to the openings in the tracker-board and to restore said sheet to a proper position in the event of its displacement by the conjoint movement of said sheet-contacting members in the same direction upon the sidewise displacement of said sheet as a whole.

3. The combination of a tracker-board having a series of openings in it, means for carrying a perforated sheet whereby it may be drawn over said board, means for moving the sheet sidewise for positioning it in relation to the openings in the tracker-board and comprising in part a pneumatic motor, a control opening for governing said motor, a valve for controlling said opening, means for supporting said valve whereby it may occupy a changed position in relation to said opening without effecting material change in its control of said opening, and other associated means operable from off the opposite edges of said sheet whereby said valve may be changed in position without material change in its control of said opening in the event of the expansion or contraction of said sheet and may change the position of said valve to control said opening for governing said motor to position said sheet upon the sidewise displacement of the sheet as a whole.

4. The combination of a tracker-board having a series of openings in it, means for carrying a perforated sheet whereby it may be drawn over said board, means for moving the sheet. sidewise for positioning it in relation to the openings in the tracker-board and comprising in part a pneumatic motor, a control opening for governing said motor, a valve for controlling said opening, and means for controlling said valve to control said opening for governing said motor to position said sheet in proper relation to the openings in the tracker-board and to restore said sheet in the event of its displacement, said last-named means comprising in part members in engagement with the opposite edges of the sheet and by the conjoint and simultaneous movement of which upon expansion or contraction of the sheetsaid valve is made to occupy a changed position relatively to said opening without effecting material change in its control of said opening and by the conjoint and simultaneous movement of said members upon the side wise displacement of the sheet as a whole said valve is controlled to control said opening for governing said motor as aforesaid irrespective of the changed position of the valve in relation to said opening.

5. The combination of a tracker-board having a series of openings in it, means for carrying a perforated sheet whereby it may be drawn over said board, means for moving the sheet sidewise for positioning it in relation to the openings in the tracker-board and comprising in part a pneumatic motor, a control opening for governing said motor, a valve for controlling said opening, and means for controlling said valve to control said opening for governing said motor to position said sheet in proper relation to the openings in the tracker-board and to restore said sheet in the event of its displacement, said last-named means comprising in part independently-movable, disconnected, sheetcontacting members in engagement with the opposite edges of the sheet and by the conjoint movement of said sheet-contacting members upon the sidewise displacement of the sheet as a whole said valve is controlled to control said opening for governing said motor, as aforesaid.

6. The combination of a. tracker-board having a series of openings in it, means for carrying a perforated sheet whereby it may be drawn over said board, means for moving said sheet sidewise for positioning it in relation to the openings in the tracker-board and comprising in part a pneumatic motor, a control opening for governing said motor, a valve for controlling said opening, means for supporting said valve whereby the position thereof may be changed in relation to said opening without alfecting its functioning to control said opening, and means for controlling said valve to control said opening for governing said motor to position said sheet in proper relation to the openings in the tracker-board and to restore said sheet in the event of its displacement, said last-named means comprising in part members yieldingly maintained in engagement with the opposite edges of the sheet and by the conjoint and simultaneous movement of said members upon expansion or contraction of the sheet said valve is made to occupy a changed position relatively to said opening, but without affecting its funcdisconnected,

tioning to control said opening, and by the conjoint and simultaneous movement of said members upon the sidewise displacement of the sheet as a whole said valve is controlled to control said opening for governing said motor as aforesaid irrespective of the changed position of the valve in relation to said opening.

7. In a tracking device of the character specified, for automatically controlling the lateral position of a moving sheet, the combination comprising a pneumatic motor for laterally positioning the sheet, a control opening for governing the action of said motor, a valve for controlling said opening, means for loosely supporting said valve whereby its position may be chan ed in relation to said opening without affecting its functioning for controlling said opening, a set of members yieldingly maintained to have engagement with the opposite edges of said sheet, and mechanisms interposed between said members, respectively, and said valve and connecting, respectively, with opposite sides of said valve whereby movement imparted to said members upon the expansion or contraction of said sheet will change the position of said valve with relation to said opening without affecting its functioning to control said opening and whereby, also, said mechanisms will operate said valve to function in its control of said opening upon movement of said sheet as a whole laterally in either direction.

8. In combination, mechanism for laterally positioning a sheet, independently-movable, disconnected, sheet contacting members yieldingly maintained to have engagement with the opposite side edges of the sheet, and associated therewith means whereby said mechanism may be controlled to laterally position said sheet by the conjoint movement of said sheet-contactin members from off the opposite side edges 0 the sheet upon the sidewise displacement of the sheet as a whole.

9. In combination, mechanism for laterally positioning a sheet and means for controlling said mechanism having independently-movable, disconnected parts operable from off the opposite side edges of the sheet whereby said means may exert no influence upon said mechanism in the event of the expansion or contraction of the sheet, but may be made to exert a controlling influence upon said mechanism by the con oint movement of those of its said parts in engagement with the sheet upon the sidewise displacement of the sheet as a whole.

10. In combination, mechanism for laterally positioning a sheet, said mechanism comprising in part a pneumatic motor having a control opening, a valve for controlling said opening, independently-movable, sheet contacting members yieldingly maintained to have engagement With the opposite side edges of the sheet, and means whereby said members may control said valve from off the opposite side edges of the sheet and said members exert no influence to affect the functioning of the valve in relation to said opening upon the expansion or contraction of the sheet, but will operate through their conjoint movement to afi'ect the functioning of said valve in relation to said opening upon the side- Wise displacement of the sheet as a Whole.

11. In combination, mechanism for laterally positioning a sheet, said mechanism comprising in part a pneumatic motor having a control opening, a valve for controlling said opening, means for supporting said valve whereby its position may be changed for controlling said opening or the position thereof may be changed in relation to said opening Without affecting its functioning for controlling said opening, and means whereby said valve may be controlled from. off the opposite sides of said sheet and the position of said valve be changed in relation to said opening Without affecting its functioning for controlling said opening upon the expansion or contraction of the sheet and the position of said valve be changed for controlling said opening upon the sidewise displacement of the sheet as a Whole.

OLIVER H. ARNO.

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