US1238884A - Automatic playing device for stringed instruments. - Google Patents

Description

B. L. CARTMELL.

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

APPLICATION FILED APR-'23. I915.

1,238,884. Patented Sept. 4,1917.

3 SHEETSSHEET I.

III IIIIIIIII.

Il' I/I/h ammo o B, L. CARTIVIELI...

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

APPLICATION FILED APR- 23| IBIS.

1,288,884. Patented Sept. 4,1917.

3 SHEETSSHEET 2.

II I I w r :EZZ. w /00 /3 B. L. CARTMELL.

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

APPLICATION FILEDIAPR. 23. 1915. 1,238,884. PatentedSept. 4, 1917.

3 SHEETS SHEET 3.

UNITED STATES PATENT OFFICE.

BENJAMIN L. CARTMELL, OF DAYTON, OHIO.

T 0 all whom it may concern:

Be it known that I, BENJAMIN L. CART- MELL, citizen of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in .Automatic Playing Devices for Stringed Instruments, of which the following is a specification.

My invention relates to automatic musical instruments and more particularly to an automatic playing apparatus applicable to stringed instruments without necessitating any changes in the construction of the instrument or involving any mutilation thereof.

The object of the invention is to simplify the structure as well as the means and mode of operation of such apparatus whereby it will not only be cheapened in construction, but will be more efficient in use, positive in action, and unlikely to get out of repair.

A further object of the invention is to provide improved form of string stopping devices and control means therefor and improved means for operating the plectrums or picking devices. Y

A further object of the invention is to provide means for automatically varying the intensity or modulating the sounds produced, thereby effecting expression in the reproduction of the musical composition.

With the above primary and other incidental objects in view, as will more fully appear in the specification, the invention consists of the features of construction, the parts andvcombinations thereof, and the mode of operation or their equivalents, as hereinafter described and set forth in the claims.

Referring to the drawings, Figure 1 is a front elevation of the assembled playing apparatus applied to a banjo. Fig. 2 is a side elevation, partly in section, of the mechanism. Fig. 3 is an enlarged detail view of the string stopping devices viewed from the side. Fig. l is an end elevation ofthe musical instrument illustrating the plectrums and operating devices therefor. Fig. 5 is a trans verse sectional view of the string stopping devices. Figs. 6 and 7 are detail plan view and vertical sectional view of the valve chest. Fig. 8 is a detail perspective view of the plectrum and its mounting. Fig. 9 is a detail perspective view of two of the string stopping devices. Figs. 10 and 11 are diagrammatic views of the movement of the plectrum.

Like parts are indicated by similar char- Specification of Letters Patent.

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

I Patented Sept. 4, 1917.

Application filed April 23, 1915. Serial No. 23,515.

acters of reference throughout the several VIEWS.

In the drawings there has been shown a complete playing mechanism adapted to be controlled by a perforated master or music sheet involving novel means for accomplish ing the winding and rewinding of the music sheet and also improvements in the control valve for pneumatically operated mechanisms of this character. For obvious reasons, however, the present invention is re stricted to those devices relating directly to the manipulation of the stringed instrument, viz., the fingering, picking, and expression controlling devices. The remaining novel features disclosed herein, including the con trol mechanism for winding and rewinding of the music sheet and the valve chest and other devices are not abandoned, but, as at present advised, will form the subject matter of separate applications.

Referring to the drawings, 1 is the main frame or supporting structure upon the front board 2 of which there is detachably connected by suitable clamping means a stringed instrument, which, in the present instance, is a banjo. It is obvious that other forms of instrument such as a guitar, mandolin, zither, harp or other stringed instruments may be substituted for the banjo shown in the drawings.

At its upper end the instrument rests upon a pillow block 3 secured to the front board 2 to which the instrument is attached by a clamping plate 4 overlying the head of the instrument and attached to the pillow block by clamping screws 5. At its lower end the instrument is secured to a bar 6 projecting from the front board 2 by means of clamps or clevises 7 engaging the head bar 8 of the banjo and a T shaped extension 9 of the bar 6.. Located in the lower front portion of the frame 1 are the wind and rewind rolls 10 and 11 upon which are carried from one to the other the perforated music sheet 12. This perforated sheet 12 passes over a tracker bar 13 intermediate the rolls having therein a plurality of orifices each connected by a conduit l i within the valve chest.

In the drawings, for convenience, two valve chests 15 and 16 have been shown. In this particular construction the chest 15 pertains wholly to the string stopping devices while thevalve chest 16 is connected with the picking and modulating mechanism and also with various control devices. It is obvious, however, that all the devices may be Q011- trolled from a single valve chest. chests 15 and 16 communicate through a conduit 17 with the actuating bellows or pump 18, the movable side of which is connected by a pitman 20 with a crank arm 21. The crank shaft 21 is rotated by a motor 22 or any other suitable driving device' In the present instance the motor 22 is connected by a belt 23 with a pulley 24 upon the crank shaft. Associated with the bellows 18 is the usual equalizer 25.

The wind and rewind rolls 10 and 11 are driven by means of a belt 26 from the pulley 27 on the crank shaft to a pulley 28 upon the counter shaft 29 of the wind and rewind mechanism. The counter shaft 29 carries a sprocket wheel 30 connected by a chain '31 with a corresponding" sprocket 32 upon the shaft of the. rewinding roll 11. The sprocket 30,'however, is loose'upon the counter shaft 29 and is adapted to be en gaged therewith by means of a sliding clutch member] 33 controlled by an oscillatory lever 34. 'Whenthelever 34 is reversed the sprocket30 is disconnected from the shaft 29 and a gear pinion '35, carried by the clutch member 33, is caused to mesh with a. gear 36 upon the shaft of the winding roll 10. The operating mechanism thus far described is that generally found in pneumatically operated mechanical playing apparatus. The control lever 34 is actuated to effect the windin-gand rewi-nding of the music sheet by means of a pneumatic or bellows 37 which is expanded by a spring 38 thereby causing the clutch member 33 to be engaged with thesprocket 30 whereby the rewinding roll 11 is driven from the counter shaft 29. The pneumatic 37 is connected through the valve chest with the main bellows or pump 18 independent of the tracker bar. The construction is such that the pneumatic 37 is collapsed whenever the main bellows '18 is in effective operation. Upon the contraction of the pneumatic or bellows 37 under the influence of the main bellows or pump 18 the clutch member 33 is shifted to effect the winding of the music sheet.

For convenience of manufacture the valve chests have been made up of a series of layers or thicknesses of material, preferably wood, superposed one upon the other. Refer-ring to Figs. 6 and 7, these various thicknesses or layers of material have been designated as a, b, c, d, e, and f. The lowermost portion a is provided with perforations or orifices 40 with which the tubes or conduits 14 leading from the tracker bar communicate. In the superposed thickness b there are provided a plurality of enlarged openings 41 forming chambers concentric with These the orifices. 4Q. These openings or eham- 6 hers 41 are closed on their upper side by a die hragm 42 of flexible material such as rub er, leather, fabric, or other material, forming an expansible side for the chamber which is commonly termed in the trade l as the pouch. The succeeding layer or thickness 0 comprises merely a marginal frame forming intermediate the layers or thicknesses b and d a suction or vacuum chamber 43 which is common to all the valve mechanisms in the chest. This suction chamber communicates with the main bellows or-pump 18 through the conduit 17. The succeeding layer or thickness d, forming the upper wall of common suction or vacuum chamber is provided with a plurality of orifices 44 communicating therewith. The thickness or layer 0 superposed on the thickness d is provided with elongated openings 45 re 1 istering with the orifices 44. Located -in the openings or chambers 45 are valve heads 46 ,havin pendant stems 47 projectin through t e orifices 44 and resting at thei lower end upon the flexible diaphragm 42. The top or cover of the chest is provided with two orifices leading to the elongated chamber 45, the orifice 48 being a vent to the atmosphere adapted to be controlled by the valve 46', and the second orifice 49 communi cates with the pneumatic control device. To prevent the displacement of the valve head 46 a stud or pin 50 is driven into the portion (l beside the valve head 46. Leading from the main suction or vacuum chamber 43 to the pouch 41 is a small duct 51 commonly known as the bleed hole. This duct or bleed hole is controlled by a screw 52' by the adjustment of which it may be partially closed to regulate the passage of w air therethrough and thereby control the rapidity of action. The construction is such that the air is exhausted from the main suction or vacuum chamber 43 by the operation of the pump or bellows 18 thereby maintaining a partial vacuum therein which is extended through the bleed holes 51 to the pouches or chambers 41 which are thereby maintained in a state of partial vacuum. When a perforation of the music sheet registers with a corresponding orifice of the tracker bar, air is admitted through the orifice and the conduit 14 connected therewith to the corresponding pouch or chamber 41. The inlet 40 being larger than the bleed hole 51, the air rushes into the chamber or pouch 41 at a greater rate than it can be withdrawn by the pump or bellows 18 acting through the common vacuum chamber 43. The result is that the dia-' phra m or flexible side 42 of the pouch or cham er 41 is expanded upward by atmospheric pressure. Its movement, being transmitted through the stem 47 of the valve 46 resting thereon, causes the valve 46 to be lifted to open the orifice 44 and to close the vent 48. The orifice 44 being opened and the vent closed, the influence of the suction bellows or pump 18 is extended from the common suction or vacuum chamber 43 through the orifice 44, chamber 45, orifice 49 and conduit 53 connected therewith to the pneumatic control device from which the air is exhausted, causing the pneumatic to collapse and thereby perform its function. The master sheet having continued to move across the tracker bar and the perforation having been moved from registry with the orifice of the tracker bar, thereby closing the latter, the continued action of the main bellows or pump 18 will exhaust the air from the chamber or pouch 41, causing the flexible side or diaphragm 42 thereof to contract and permitting the valve 46 to descend to close the orifice 44 and at the same time open the vent 48. The opening of the 'vent 48'permits the entrance of air through the vent 48, the chamber and the connecting conduit 53 to the operated pneumatic which is expanded to normal by its usual spring. For convenience in tracing the parts the conduits connecting the valve chest with the several sets of pneumatics have been sep'arably identified. The conduits leading to the fingering or stopping de vices'have been designated as 53 the conduits leading to the modulating or expression control mechanisms are designated as 53", and those controlling the Wind and rewind of the music sheet are designated as 53 and 53 respectively.

In the drawings the banjo has been shown provided with but four strings, the fifth or thumb string having been omitted. The stringstopping devices are arranged as follows: Located on the front board 2 on opposite sides of the neck of the instrument are two boxes or housings 54 and 55. Located in each of these housings are a plurality of pneumatics or small bellows which, for convenience, are arranged in two series, one above the other. Hinged to the outer walls of the boxes or housings 54 and 55 and pro jecting inward therefrom are parallel pivoted arms 56 preferably arranged in pairs. Each arm 56 is connected by a suitable link -with a. corresponding pneumatic or bellows 57. i Ithas been found in practice that the preferable form of connecting link comprises a string or cord 58 attached at 59 to the movable side of the pneumatic or bel lows and extending upward to and attached to the hinged or pivoted arm 56. The end of the pivoted arm 56 is preferably provided with a diagonally disposed hole or orifice 60 through which the connecting cord 58 is threaded and the end of the cord is securedby being wrapped arounl a con veniently located screw 61. However, in lieu of the diagonal perforation. the end of the arm may be provided with a staple or eye 62, as shown at the left in Fig. 9.

Held by each of the swinging or pivoted arms is a thin blade-like extension 63 having a laterally projecting foot 64 overlying the corresponding string of the instrument. The bladelike extensions 63 of the swinging arms are located on adjacent sides of the arms whereby they will lie closely :uljacent one to the other with their laterally extended feet 64 alined. adjacent to the corresponding fret of the instrument neck. The inner walls of the housings 54 and 55 are slotted to form guides for the stopping devices, through which slots the extensions 63 extend. As shown in the drawings, the swinging arms of the respective boxes or housings 54 and 55 are alined one with the other so that the extensions of the arms from one box or housing engage the two strings to the right and those from the box to the left engage the two strings to the left. The extensions 63'of the arms pertaining to the medial strings are recessed or notched as shown at 67 whereby when depressed they will not interfere with the outermost strings. The adjustment of the stopping arms or fingers is readily accomplished by the loosening or tightening of the strings or cords 58. The feet or engaging portions 64 are covered on their under surface with leather, rubber or other suitable material which will prevent the abrasion of the strings and also obviate any chatter or noise as the strings are pressed into engagement with the neck. The music sheet is provided with one set of perforations, as at 65, which pertain to the pneumatics controlling the fingering or string stopping devices and another set of perforations'66 which pertain to the pneumatics controlling the picking apparatus or plectrums.

Located on opposite sides of the body of the instrument are pneumatics or bellows 69 controlling the operation of the picking devices or plectrums, one for each string and plectrum. In the present instance these pneumatics have been arranged in pairs. The pneumatics carry at their upper ends a frame or head 70 supported on the stationary side of the pneumatic from which extend inwardly disposed arms 71. Set screws 72 in the frames or heads 70 serve to limit the movement of the flexible sides of the pneumatics and thereby form the means of adj usting the degree of movement of the plectrum. Secured to the opposite sides of the instrument body by means of cross heads 73 engaging beneath the nuts of the head clamps are studs 74 which .engage the inward projecting arms 71 and serve to support the body of the instrument rigidly in relation with the frame and operating mechanism. The studs 7 4 extend above the arms 71 and support a transverse bar 7 5 which may be adjusted vertically to and from the head of the instrument by the adjustment of the nuts 76 and 77 upon the studs 74 to vary the relation of the plectrums with the strings. The pickers or plectrums 78 are carried upon bell cranks 79 both slidingly and pivotally mounted upon the cross bar 7 5. Each bell crank 79 is provided with a slot 80 through which projects a stud or screw 81 which forms the pivotal connection of the bell crank during its oscillatory movement and a guide for its sliding movement. Bearing upon the bell crank 79 about the stud or screw 81 is a leaf or blade spring 82 which acts as' a brake affording frictional resistance to the sliding movement of the bell crank 79. Adjacent to the picker or plectrum 78 the bell crank 79 is provided with a pin 83 which engages a slot 84 in a swinging arm 85 pivotally connected upon the cross bar 75. To obviate any metallic chatter or noise incident to the engagement of the pin 83 with the arm a string 86 is tied across the slotted portion of the arm to be engaged by the pin. The end of the bell crank 79 is turned outward, as at 87, and the picker or plectrum 78 is clamped thereto by a screw or bolt 88 and clamp plate 89. The lateral arm of the bell crank carries a swivel head 90 having interposed washers 91 of leather or other suitable material to prevent rattle or noise. An actuating link or rod 92 hinged to the edge of the movable side of the pneumatic and adjustably connected to the swivel head 90 servesto actuate the bell crank 79 to cause the picker or plectrum 7 8 to engage the strings of the instrument. As the pneumatic or bellows is collapsed by the exhaustion of the air therefrom, as heretofore described, the pull exerted upon the connecting rod 92 oscillates the crank arm 79 downward about the pivotal stud 81 projecting the picker or plectrum 78 into the plane of the string. The continued movement of thepneumatic causes the bell crank 79 to slide longitudinally upon the stud or screw 81 within the limits of the slot 80 until the plectrum 78 has been drawn across the string. Upon the reverse movement of the movable side of the pneumatic the bell crank is first oscillated upward about the stud or screw 81 which at such time will stand adjacent to the opposite ends of the slot 80 and thereafter the bell crank 79 will be reciprocated to carry the plectrum 78 over and beyond the string. The swinging arm 85 serves to guide the bell crank and insure its proper path of travel. The leaf or blade spring 82 afiords sufficient pressure or friction to prevent the reciprocatory movement of the bell crank prior to its oscillatory movement. The path of travel of the plectrum is clearly illustrated in the diagrammatic views Figs. 10 and 11. It will be understood that there is a bell crank and plectrum with its connecting rod and pneumatic for each string. In the present instance two bell cranks have been mounted upon each side of the transverse bar 75 and, as before stated, the pneumatics are arranged in pairs upon opposite sides of the body. Each pneumatic is connected by a link or rod 92 with its corresponding bell crank and plectrum. These plectrums are operated in proper sequence and in proper time order with the fingering or stopping devices under the control of the perforated music sheet in which the perforations 66 controlling the plectrums are located in definite relation with the perforations 65 controlling the fingering or stopping devices.

After the playing of the musical composition has been completed a perforation in the sheet is brought into registry with the corresponding orifice in the tracker bar controlling a pneumatic or bellows 93 through the conduit 53 to effect the rewind of t e music sheet. The pneumatic 93 is connected by a link or cord 94: with a pivoted arm 95 mounted upon a hinged door or fla 96 affording an inlet for air to the equa izer and main bellows 18. This door or fla 96 is normally held closed by a spring 97. The collapsing of the pneumatic 93, however, lifts the pivoted arm 95 into the path of a lug or projection 98 upon the main bellows 18 which, upon its succeeding operation by engaging the end of the swinging arm, forces the door or flap 96 open against the tension of the spring 97 where it is engaged and held by a detent finger 99 provided with'a shoulder to engage a stud or pin in said flap or door. This admits air to the equalizer and main bellows and renders the pneumatic mechanism inoperative during the rewinding of the perforated sheet. The admission of air permits the pneumatic 37 to expand under the influence of its spring and thereby cause the engagement of the gear inion 35 with the gear 36 to effect the rewinding of the music sheet under the influence of the motor inde endent of the pneumatic mechanism. As t 0 rewinding operation is completed a stud or pin 100 located in a groove 101 in the winding roll 11 engages the end of a pivoted spring actuated finger 102 carried upon the end of a lever 103 fulcrumed at 104 upon a suitable bracket and serves to oscillate said lever against the tension of its sprin 105. This lever carries at.its rear end a downward extending hooked extension 106 adapted to engage and lift the detent 99 when the lever is oscillated upward. The lifting of the detent 99 serves to disengage said detent sion of the from the flap or door 96 permitting said oor to close under the influence of its spring 97 whereupon the pump or main bellows 18 again becomes operative and the operation of the mechanism is repeated. Thus the winding and rewinding of the perforated sheet is automatically accomplished and the moven'ient'of the music sheet is automat1- callyreversed at each limit of its travel. 10

In order tovary the intensity of the sound and produce modulation of expression in the playing, there is provided upon the body bar 8 ofthe instrument a flexible spring blade 107 carrying at its free end a mute or damper .108 adapted to be lifted into engagement with the under side of the instrument head. To elevate the mute or damper 108 to operative position against the tenspring blade 107 there is provided a pivoted lever 109 having a pin 110 engaging beneath said spring blade and at its opposite end provided with a connection 111 to an arm 112 carried by a pneumatic 113. The construction is such that as the pneumatic 113 is collapsed by the exhaustion of the air therefromthe lever 109 will be oscillated to. elevate the damper or mute intocontact with the instrument head. Located adjacent to the pneumatic 113 is a pivoted arm 114 having therein a notch 115 adapted to engage a pin or stud 116 in the movable" side 'of the pneumatic to lock said pneumatic in collapsed position and so 'maintain the mute or damper in operated condition until released. To release the mute or damper there is provided a second pneumatic 117, the movable side of which is connected by a link or cord 118 with the pivoted arm 114 whereby when said second pneumatic 117 is collapsed the arm is elevated from engagement with the pin and the first mentioned pneumatic is permitted to expand. It is pneumatics 113 and 117 are controlled by perforations in the music sheet registering with corresponding orifices in the tracker bar.

From the above description it will be apparent that there isthus provided a device of the character described possessing the particular features of advantage before enumerated as desirable but which obviously is susceptible of modifications in its form, proportion, detail construction, or arrange ment of parts without departingfrom the principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has been described in language more or'less specific as to certain structural features, it is to be understood that the invention is not limited to any specific details but that the means and construction herein described comprise but one mode of putting the invention into effect and the into be understood that these vention is therefore claimed broadly in any of its possible forms or modifications with in the scope of the appended claims.

Having thus described my invention, I claim:

1. In an automatic playing apparatus for stringed instruments, a plectrum, a bell crank on which the plectrum is carried capable of both oscillatory and reciprocatory .movement in relation with its fulcrum, means for initially oscillating the bell crank to carry the plectrum into the plane of the string and thereafter reciprocating the bell crank to carry the plectrum across the string.

In an automatic playing apparatus for stringed instruments, a plectrum, a movable support on which the plectrum is carried capable of both oscillatory and reciprocatory movement, and means affording yielding resistance to the reciprocatory movement of the supportgreater than the resistance to the oscillatory movement thereof and actuating means therefor.

3. In an automatic playing apparatus for stringed instrun1ents, a plectrum, a movable carrier therefor, a support for the carrier, a connection between the carrier and support in relation with whichthe carrier is capable of independent oscillatory and reciprocatory movement, an actuator for the carrier connected thereto at a point normally offset in relation with the supporting connection, and means for operatively controlling the actuator.

4. In an automatic playing apparatus for stringed instruments, a plectrum, a movable support,- a pivotal connection about which the support is capable of oscillatory movement and in relation with which the support is slidingly adjustable, and'means for oscillating the support about said pivotal connection and thereafter sliding the support in relation therewith.

5. In an automatic playing apparatus for stringed instruments, a plectrum, a support therefor having an elongated .slot therein, a pivotal stud engaging in the elongated slot, and means for oscillating the support about the pivotal stud and thereafter sliding the support upon said stud within the limits of the slot.

6. In an automatic playing apparatus for stringed instruments, a plectrum, a reciprocatory support therefor, a swinging arm engaged with the support and means for reciprocating the plectrum support while engaged by the swinging arm.

7. In an automatic playing apparatus for stringed instruments, a plectrum, a plectrum support, a swinging support for the plectrum support, and a fixed support therefor in relation with which the support is slidingly movable.

8. In an automatic playing apparatus for stringed instruments, a bell crank lever having a sliding pivotal connection,- a plectrum carried by said bell crank lever, and means for restraining the sliding movement of the bell crank lever until the pivotal movement thereof is effected.

9. In an automatic playing apparatus for stringed instruments, a plectrum, a movable support therefor, a reciprocatory link connected with the plectrum support, a shifting pivotal connection for the support and means for actuating said movable support.

10. In an automatic playing apparatus for stringed instruments, at plectrum, a pivoted support therefor, means to initially oscillate the support and thereafter move it in a direction radially in relation with the axis of its initial oscillatory movement.

11. In an automatic playing apparatus for stringed instruments, a plectrum, a bell crank by which the plectrum is carried, a reci rocatory actuator connected to one arm of tlie bell crank, and a shifting pivotal connection for the bell crank.

12. In an automatic playing apparatus for stringed instruments, a plectrum, a bell crank by which the plectrum is carried, a shifting pivotal connection for the bell crank, an actuator therefor, and means retarding the shiftin movement of the bell crank until said bel crank has been initially oscillated about said pivotal connection.

13. In an automatic playing apparatus for stringed instruments, a plectrum, a bell crank by which the plectrum is carried, a shifting pivotal connection for the bell crank, and actuating means initially oscillating the bell crank about its pivotal connection and thereafter shifting it in relation therewith.

14. In an automatic playing apparatus for Copies 0! this patent may be obtained for five cents each, by addressing the stringed instruments, a plectrum, a bell crank by which the plectrum is carried, a sliding pivotal connection for the crank, a swingm arm controllin the free end of the cran during its shiftin movement, and means for actuating the bel crank.

1 5. In an automatic playing apparatus for strin ed instruments, a plectrum, a bell crank by which the plectrum is carried, a sliding pivotal connection for the bell crank and a brake member retarding the shifting movement of the bell crank.

16. In an automatic playing apparatus for stringed instruments, a plectrum, a bell crank by which the plectrum is carried, a sliding pivotal connection for the bell crank, and a spring exerting pressure upon the bell crank to retard its shifting movement.

17 In an automatic playin apparatus for stringed instruments, a moc ulating device comprising a damper movable into engagement with the head of the instrument, means for moving the dam er to operative position, a lock therefor, an means to automatically release the lock.

18. In an automatic playin apparatus for stringed instruments, a mo ulating device comprisin a damper movable into engagement wit the head of the instrument, a pneumatic adapted by its operation to project the dam er into en agement with the head, means or locking t e damper in operated position, and a second pneumatic adapted upon operation to release the damper.

In testimony whereof, I. have hereunto set my hand this 20th dav of April, A. D. 1915.

BENJAMIN L. CARTMELL.

Witnesses:

HARRY F. NOLAN, F. L. WALKER.

"Gommlntoner of Patents,

Washington, D. C."

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