US2066581A

US2066581A - Tuning apparatus

Info

Publication number: US2066581A
Application number: US51369A
Authority: US
Inventors: Victor H Severy
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-11-25
Filing date: 1935-11-25
Publication date: 1937-01-05
Anticipated expiration: 1954-01-05

Description

Jan. 5, 1937. v, H SEVERY 2,066,581

TUNING APPARATUS Filed Nov. 25,' 1935 6 Sheets-Sheet l gmc/whom im wwm Jan. 5, 1937. v. H. sE-:vERY

TUNING APPARATUS Filed Nov. 25, 1955 6 Sheets sheet 2 Jan. 5, 1937. v H. sEvERY TUNING APPARATUS Filed Nov. 25, 1955 s sheets-shee 5 Jan. 5, 1937. v. H. SEVERY TUNING APPARATUS Filed Nov. 25, 1935 6 Sheets-Sheet 4 "Il, "NNUU" A In M I lll l 3215215123456 Vido/'H eve/y Jan. 5, 1937. V. H SEVERY 2,066,581

TUNING APPARATUS Filed Nov. 25, 1935 6 Sheets-Sheet 5 ilil Gum/mm 3 Jan. 5, 1931.

Filed Nov. 25, 1935 l l6 Sheets-Sheet 6 FWF-@Zip zzo- Z0# l l @7 102, 101, y j Y1@ Z047 I 105, l J l 94; 96)

k l 106 98* L* f l wue/wto/o Tf/CZOIH Sever Patented Jan. 5, 1937 UNITED STATES PATENT OFFIEE 24 Claims.

This invention relates to tuning apparatus, and while features of the invention may be employed for tuning musical instruments of diiferent kinds, the invention is intended to be particularly useful in tuning reed instruments. In the present speciiication the invention is described .as applied to the tuning of harmonicas. At present, the tuning of harmonicas is accomplished with considerable difficulty, and requires the services of a highly paid expert.

The general object of this invention is to provide tuning apparatus of simple construction, which can be employed for tuning harmonicas or similar instruments; also for testing the pitch of vocal notes.

A further object of the invention is to provide apparatus for this purpose, in which the reed to be tuned can be vibrated, and the period of frequency of the reed accurately indicated; also to provide simple means for altering the frequency and period of vibration of the reed to tune the same.

A further object of the invention is to provide a simple and compact apparatus for this purpose, which will enable the reed plate of a harmonica to be set up in part of the apparatus to enable the reeds to be accurately tested in succession to determine their period of vibration, and to provide means for immediately operating upon each reed to alter its period, to tune the same.

For tuning the reeds, the apparatus preferably includes a gang of test vibrators to cooperate with each reed, and indicating whether the reed is sharp or flat; and one of the objects of the invention is to mount these vibrators so that there will be no interference between the individual vibrators when they function, by reason of the close proximity of the other vibrators in the gang.

In its preferred form, the invention involves the use of a plurality of test boxes or units, each of which contains a gang of test vibrators corresponding to each reed, and one of the objects of the invention is to provide an improved construction and arrangement for the apparatus on the interior of these test boxes or units; also to provide means whereby the functioning of the apparatus in one test box cannot be interfered with by the proximity of apparatus in adjoining test boxes.

Further objects of the invention will appear hereinafter.

The invention consists in the novel parts and combination of parts to be described hereinafter,

all of which contribute to produce an eflicient tuning apparatus.

A preferred embodiment of the invention is described in the following specification, while the broad scope of the invention is pointed out in the appended claims.

In the drawings:

Figure 1 is a side elevation of the table carrying the apparatus, and also illustrating two adjacent banks of test boxes, but omitting the banks of test boxes beyond the banks illustrated. In this view a portion of the wall of the table is broken away to indicate the position of the instrument board.

Figure 2 is a section taken through one of the test boxes in a plane substantially parallel with its longitudinal axis. This View is taken on the line 2 2 of Fig. 3, and particularly illustrates the arrangement of the test vibrators in the box, which correspond to the reed that is to be tuned, and also showing their relation with respect to the common lamp or source of illumination. This view indicates two adjacent test boxes broken away.

Fig. 3 is a vertical section taken about on the line 3-3 of Fig, 2 through the lowest test box in the illustrated bank, and also indicating a portion of the supporting table and part of the test box next above the one illustrated in section.

Fig. 4 is a developed front elevation taken about on the line 4-4 of Fig. 2, but upon an enlarged scale, and particularly illustrating a number of the gang of the test vibrators illustrated in Fig. 2, This view is upon a slightly enlarged scale, and the parts at the lower portion of the apparatus are broken away.

Fig. 5 is a side elevation in partial section showing test vibrators, and particularly illustrating the reflector carried by it and the means for mounting the reflector in position.

Fig. 6 is a section taken about in the plane of the line 6-6 of Fig. 1, and diagrammatically illustrating the instrument board and the lower tier of several banks of test boxes; and also showing screens which are employed at the forward ends of the boxes to be observed by the operator who is tuning the instrument, and by the use of which the tuner can determine visually whether the reed being tuned is sharp or flat.

Fig. 7 is a vertical section through the forward portion of the table with certain parts broken away. This view is upon an enlarged scale, and particularly illustrates the arrangement of the preferred means for effecting the vibration of the reed, together with means for holding the reed plate in position when it is being tuned, and means cooperating to enable the reed to be immediately altered to increase or decrease its frequency.

Fig. 7a is a fragmentary View, and is a detail side elevation particularly illustrating yielding means which I prefer to employ for pressing the tools of the instrument against the face of the reed when it is necessary to remove some of the material of the reed to change its period.

Fig. 8 is a plan of one end of the table illustrated in Fig. 7, with certain parts broken away, and further illustrating the general arrangement of the apparatus illustrated in Fig. '7.

Fig. 9 is a section taken along the line 9-9 of Fig. '7, and particularly illustrating a reed plate of a harmonica with the reeds carried by it, and further illustrating the means for holding the reed plate in position when the reeds are being tuned.

Fig 10 is a front elevation with certain parts broken away, of one of the screens employed in tuning a reed, and indicating the location of reflected light beams on the screen when the reed is in perfect tune.

Fig. 11 is a view similar to Fig. 10, but indicating the relation of reflected light beams on the indicating screen when the reed is flat; that is to say, when the period of the reed is too low.

Fig. l2 is a diagrammatic View of the apparatus, and indicating the electrical apparatus employed, together with a wiring arrangement which can be employed in practicing the invention.

Before proceeding to a more detailed description of the invention, it should be stated that in the operation of the preferred embodiment of the apparatus, the reed to be tuned is vibrated, and the vibration of the reed controls apparatus operating to develop impulses in a circuit having the same frequency as the frequency of the reed in its natural vibration. By means of this, current indicating means is controlled to show whether the reed is sharp or flat. For this purpose the impulse current is amplified and passed through electromagnets of a gang of test vibrators which are graduated to vibrate at frequencies slightly above and slightly below the frequency for the reed that is being tuned. The middle test vibrator has exactly the period of vibration or frequency of the note that the reed should produce if in perfect tune. In tuning a reed, the timer observes the screen before him on which light is reflected from the test vibrators, and the position of the maximum elongated bar of light from the test vibrators, indicates whether the reed is sharp or flat.

In testing the reeds of a harmonica, the reed plate is mounted in suitable means in front of the operator or tuner, and as soon as he ascertains from the visual indicator whether the reed is sharp or fiat, he immediately operates mechanism which will correct the error in the reed, and this is preferably accomplished by removing a small amount of material from the face of the reed, either toward the free end of the reed or toward the fixed end of the reed, depending upon the relation of the period or frequency to the correct period or frequency for that reed.

The vibration of the reed to be tuned is preferably effected through the agency of pneumatic means, preferably including a suction box in which a partial vacuum is maintained, so that by the opening of a valve corresponding to the reed being tuned, air will be drawn in to the suction box past the reed, thereby causing the reed to vibrate, and the vibration of this reed causes vibrations in the air within the suction box at the same frequency as the reed. Associated with the suction box a pick-up device is provided in which the impulses have the same frequency as the reed. This is the current which is amplified, and which cooperates with other means to effect the vibration of the gang of test vibrators. Of course, the test vibrator which is most nearly in tune with the reed being tuned, will vibrate. If this happens to be the middle vibrator of the gang, the indicator scale as shown in Fig. l0, will indicate this, and will indicate to the tuner that no tuning is necessary for the reed. Otherwise, the tuner will employ the means to correct the reed, and after correcting it will re-test it to determine whether the reed is now in tune.

Referring more particularly to the parts, and especially to Figs. l to 3, I indicates a table for supporting the apparatus, and toward the rear of this table a plurality of test boxes 2 are provided, said test boxes being arranged in vertical banks and horizontal tiers. The reed plate, the reeds of which are to be tuned, is set up in a holder 3 near the front of the table (see Fig. 7) in which 4 indicates the reed plate, and 5 indicates a reed which is being tuned. The holder 3 is in the form of a. block against the forward face of which the reed plate 4 is held, and back of each reed slot 6 in the reed plate a chamber I is formed in the holder 3, which communicates through an air duct 8 and a valve 9 with a suction box I0, said suction box being maintained under a partial vacuum by a tube I I or other means connected with an air pump. Associated with the suction box and preferably within the same, I provide a pick-up device I2, which is preferably in the form Of a condenser microphone, or a crystal astatic microphone. Each valve 9 is normally held closed by resilient means such as a coil spring I3 pressing against the tail of a lever I4 that carries the valve, and the valve can be opened at will by an actuating lever I5 provided with an operating push bar or plunger I6 guided vertically in the table top I1. When the valve 9 is opened, air rushes in past the reed 5 and causes it to vibrate, and this vibration is imparted at the same frequency to the air passing through the suction box,

thereby causing the microphone I2 to produce imi pulses in an electric circuit passing through the circuit wires I 8 and I 9 that connect to the microphone. These circuit wires I8 and I9 are connected up into a circuit indicated in Fig. 12, to be described hereinafter, and the circuits controlled by this microphone include circuit wires 20 and 2I, which lead to all the gangs of test vibrators 22 (see Figs. 2 and 3) of one of the test boxes 2, which is being employed in connection with the reed that is being tuned. Each test vibrator is preferably mounted on a vibrator frame 23 that is in the form of a permanent magnet, one pole 24 of which is the core of an electromagnet 25 connected up to the circuit Wires 20 and 2I by leads 26.

The core 24 of each electromagnet is preferably att-ached to a short leg 21 of the permanent magnet, by an adjustable connection 28, including a slot 29 which enables the magnet to be adjusted toward the vibrator or away from it, and which also permits the angular direction of the axis of the core 24 to be adjusted in a vertical plane. This adjustment taking place about the axis of a clamping bolt 30 that clamps the core at the slot 29.

The long leg of the permanent magnet 23 is provided with a knuckle 3| connecte-d by an adjustable pivot screw 32, and this knuckle carries the test vibrator fixed in the socket 33. In other words, I provide adjustable means for supporting the vibrator and its exciting electromagnet, which will enable these parts to be adjusted pivotally in a vertical plane, vand also enable the distance of the core to be adjusted with respect to the vibrator.

As indicated in Fig. 2, the test vibrators are all arranged in an arc in the test box, which has its center substantially at the location of the source of illumination, such as a lamp 34, and in order to facilitate reflecting from the lamp onto a ground glass screen 35 at the front of the box, I prefer to mount each magnet 23 on a stem 36 on which each vibrator frame can swivel. Each stem 36 is mounted in a relatively heavy base or block 31, and each stem can be clamped rigidly by means of a set screw 38.

In order to prevent any possibility of interference between the indivi-dual vibrators, I prefer to support each base or block 31 so that it is completely surrounded by insulation 31.

The lamp 34, as stated, is preferably mounted in the forward end of the box, and under the lamp a shield 39 is provided that prevents direct rays from the lamp from impinging on` the visual screen 35. In general, there is a test box corresponding to each reed that is to be tuned, but it is found in practice that the whole construction can be simplified and much of its bulk reduced by employing the thirteen vibrators in one box to tune the reed of the octave below its fundamental pitch. This is accomplished simply by increasing the input power. In other words, each reed would vibrate at half its number or regular period, if the electromagnet is sufficiently energized.

In order to prevent any interference between the different boxes during tuning, each box is mounted on insulation strips 40 (See Fig. 3) the air spaces between` the strips communicating with the interior of the boxes through air vents 4| to cool the boxes. These air vents are covered with metal curtains or straps 42.

Each test vibrator is preferably formed of spring steel, which is properly tapered and having an opening to form a reflector socket (see Fig. In this reflector socket 43 a small silvered glass mirror 44 is mounted and secured in place by a backing of thin cork 45, which is secured to the mirror and to the adjacent face of the vibrator by means of Canada balsam. This adhesive seems to resist the tendency of the vibration to loosen up the mirrors. Hard materials used for this purpose have been found to crystallize and shake out so as to loosen the mirror, but a semi-plastic material such as Canada balsam, is most satisfactory for this purpose.

Referring to Fig. '1, the preferred means illustrated for holding the reed plate 4 in position, comprises a rail 46 set in the groove extending along the table, and this rail carries a plurality of set screws 41 which clamp up against blocks 48 respectively, and these blocks clampup against the lower edge of the reed plate. The reed plate may rest on a strip or hatten 49 extending along the forward face of the holder `3. The upper edge of the reed plate 4 may be held back against the forward face of the holder 3 by means of a plurality of fingers 50, which are secured to a common shaft 5| supported on brackets 52 on the upper face of the holder 3. 'I'hese fingers are mounted on the shaft 5| so that the rotation of the shraft will lift all of the fingers off of the reed plate.

The reed plate is placed in the holder so that the reeds such as the reed 5, incline outwardly and upwardly from their lower ends, which are fixed to the reed plate.

In order to facilitate the removal of a small quantity of material from the reed toward its fixed end or toward its free end, I prefer to employ a carriage 53 mounted to slide on a guide 54 toward or from the holder 3, and this carriage preferably supports two spindles 55, which slide freely through bracket arms 56 extending up from the base of the carriage 53. Between the bracket arms 56, belt pulleys 51 are provided, which are non-rotatably mounted on the spindles 55. These belt pulleys 51 are driven by a belt 58 that is driven by a small electric motor 59 (see Fig. 8) that is supported on the base of the carriage.

The forward ends of the spindles 55 are provided with chucks 60 for securing abrading or cutting tools 6|, such as small milling tools or grinders, the end faces of which are adapted to come against the forward face of the reed 5 when the spindle is advanced. The means for advancing either spindle and pressing it against the face of the reed when it is necessary to remove some of the material from the reed, preferably includes yielding means that insures that a very slight force will press the tool against the reed. For this purpose I prefer to provide a pusher device 62 that comprises an operating handle 63 pivotally mounted at 64 on the outer casing or hood 65 that envelops the belt pulleys, and the inner end of this lever carries two pivotally attached pusher fingers 66, the forward sides of which engage the rear ends of the spindles 55.

The pusher fingers 66 have offset tail levers 61 with coil springs 68 respectively, located between them and the rear sides of the cross head 69 that is formed at the forward end of the lever 63 (see Fig. 7a).

In order to back up the reed 5 when it is being abraded or cut to remove some of its material, I prefer to provide the interior of the holder 3 with a backer or slide 10, which is in the form` of a thin block or plate, the forward end of which is adapted to slide forwardly,

through the chamber 1 and through the slot 6 in the reed plate 4 (see Fig. 7). The forward face 1| of this backer is preferably inclined so that it is substantially parallel to the reed 5 in its position of rest.

Suitable hand-operated means is provided for sliding the block 1|! forward just before the abrading or cutting operation takes place on the reed. For this purpose the rear enol` of each block may be provided with a pin and slot connection 12 to a bifurcated lever 13, the upper end of which is normally pulled back by a coil spring 14 so as to hold the forward end of the backer clear of the chamber 1. The rear end of the spring 14 may be attached to a post attached to the upper side of the table top |1, and this post may have a forwardly extending bracket 16 that operates as a stop for the block or backer 10 to limit its rearward movement.

The rear face of the holder 3 may be provided with clearance slots 11 for the lever 13, and blocks 10 are provided with laterally projecting lugs 18 carrying adjustable stop screws or set screws 19 passing through the lugs, and provided with lock nuts 80. On the forward stroke of the backer block 10, the forward ends of these Set screws 19 will engage the rear face of the holder 3 and limit the forward movement of the backer. These stops are necessary to prevent the backers from ever bending the reeds in a manner which might change their period.

In Fig. 6, I illustrate an arrangement of a horizontal tier of test boxes 2, the upper portion of the forward wall of each box being provided with a Ventilating opening 8|, below which the screens 35 already referred to are located. The complete unit would include live horizontal tiers, so that there would be twenty t-est boxes corresponding to each operator or tuner. The forward faces of these boxes are located near the rear of the table, at which point the instrument board 82 is located. The screens 35 may be of frosted glass or translucent paper, or any other suitable material. As indicated in Figs. l and l1, each screen is provided below it with two scales numbered from l to 6, with division lines which are substantially in line with the position of a beam of light reflected from the corresponding vibrator in that box, and adjacent this scale the letters F and S are placed on the left and right side respectively, to indicate that elongated bands of light on the left portion of the scale show that the reed being tuned is flat, and that similar elongated bands on the other side will show that the reed is sharp,

On the instrument board 82 a dial switch 83 is provided, having a pointer that cooperates with twenty numbered divisions that correspond respectively, to the twenty test boxes in the complete unit, The instrument board may also include an amplier switch 84, a power switch 85, and a voltmeter 86. In addition to this, the instrument board preferably includes a modulating lever 8`| for controlling a variable resistance for balancing circuits. The complete apparatus includes a pre-ampliiier, an amplifier, and a converter, which instruments can be conveniently placed in a box or casing 88 mounted under the table top ll (see Fig. l).

In Fig. 12, I illustrate diagrammatically the general arrangement of the apparatus and the wiring. In this diagram, 83 indicates the test-box switch already referred to in connection with Fig. 6, and 86 indicates the voltmeter which, in the diagram, is also provided with the letter V. The wires 2| for supplying the current to the electromagnet 25, run off from any one of the twenty contacts 89 on the test box switch 83. In this diagram, 90 and 8| indicate the power circuit wires, and the wire 90 connects up with two conductors or wires S2 and 93 leading respectively, to the amplifier switch 84 and the power switch 85. From the power switch current passes to a converter 94 that converts alternating current to direct current, the said wire 9| being connected to the lead 91 for the primary coil, also connected to wire 96 from switch 85.

Direct current flows through the two

conductors

98 and 98, and these conductors are connected with a preamplifier |00, which is connected by the adjacent wires I8 and |9 with the pick-up device l2, and these wires i8 and |9 also carry direct current. In the operation of the apparatus, input conductors l0! and |02 lead from the preamplifier |00 to an amplifier |03, and output conductors |04 and |05 from the amplifier lead respectively to the test box switch 83 and the lines 20 that lead to the different magnet gangs in the test boxes. One side of the amplifier |03 is provided with a modulator circuit |06 including a variable resistance |01 controlled by the modulator lever 8'! already referred to in connection with the instrument board shown in Fig. 6. From the conductor |04 a shunt line |08 extends through the voltmeter 86 and through a voltmeter switch |09, and connects up to conductor |05.

In this diagram a lamp circuit ||0 is provided,

controlled by a lamp switch (not illustrated in the apparatus) and this lamp circuit corresponds to each lamp 34 of the test box.

The general mode of operation of the apparatus will now be described.

The operator of the instrument or tuner, sits in front of the table and places the reed plate 6 in the front of the holder 3 by raising the fingers 50 and operating the clamping blocks 48. He then presses the plunger I6 corresponding to the reed that he wishes to tune, and this opens the valve 9 corresponding to this reed, opening up communication through the chamber l and duct 8 to the suction box I0, which is under a partial vacuum through the hose connection to an air pump. When the valve 9 is open, air rushes in through the reed slot past the reed 5, and causes the reed t0 vibrate at its natural frequency, and the vibration of this reed causes vibration in the air in the sound box, thereby operating the pickup l2, which produces pulsations in the current flowing through the wires |8 and I9. These wires connect with a preamplifier |00 and amplifier |03, from which the circuits pass to the test box switch 83 and the gang magnets 25 in the test box that is connected into circuit by the switch 83. The result of this is that amplified current having the same frequency as the vibrating reed 5, is passed through the electromagnets of this test box, it being remembered that the vibrators in this test box are tuned on a graduated scale so that some of them will vibrate at a higher frequency than the middle vibrator of the gang, and the others will vibrate at a slower period of frequency, it follows that the vibrator which is most nearly in tune with the frequency of the passing current, will be vibrated most actively by the passing current. These vibrators all refiect light from the lamp 34 in the box by means of their mirrors, and cast a gang of light beams on the glass screen 35. If the reed happens to be in tune, the light beam of the central vibrator, which is exactly in tune with the reed (if the reed is properly tuned) will produce a vertical elongated band of light on the screen 35, as indicated by the dotted lines in Fig. l0. If the reed is fiat, a condition such as that indicated in Fig. 11, will result as indicated by the dotted lines at the left of the center. Of course, if the reed is further out of tune, an elongated band may be produced at the outer end of the scale on either side, in which case considerable tuning of the reed will be necessary.

As soon as the tuner notes whether the reed is flat or sharp, he proceeds to remove material from the face of the reed to correct its inaccuracy. However, if the reed is nearly in tune, a very small amount of material must be removed. For example, if the reed is iiat, it must be made sharper so to speak; that is to say, it is necessary to take off a small amount of material toward the free end of the reed, and vice versa. This material is removed by the abrading tool or tools, which, in the present instance, comprise two tools 6| (see Fig. '7) one of which is substantially in line with the free end of the vibrator, and the other of which is substantially in line with the iixed end of the vibrator near its point of attachment to the reed plate. By pushing up on the lever 63, the upper cutting or grinding tool 6l will be advanced, and vice versa. In either case the hand pressure of the operator does not directly hold the tool against the reed, but pressure that can be exerted, is limited by the force of the spring 68, which is a very light spring. However, before the abrading or grinding tools 6| are applied to the face of the reed, the reed must be backed up by pulling forward the lever 'I3 to shove the backer slide or backer block 'l0 across the air chamber 1, so that its forward face 1| will rest against the rear face of the reed.

After a slight amount of material has been removed in this way, either to increase or decrease the period of the reed, it should be re-tested until it is brought into substantially perfect tune; that is to say, brought to the same frequency as the middle or center vibrator of the gang of vibrators, by means of which it is tuned.

It is evident that my apparatus can be employed for voice testing, in singing instruction, to determine whether a vocal note is sharp or flat. The vocal note is employed to actuate the microphone.

It is understood that the embodiment of the invention described herein is only one of the many embodiments this invention may take, and I do not wish to be limited in the practice of the invention, nor in the claims, to the particular embodiment set forth.

What I claim is:

l. In tuning apparatus for tuning a musical instrument having vibrators, the combination of a pick-up device vibrated sympathetically from the vibrator of the instrument that is to be tuned, said pick-up device operating to develop electric impulses at the same frequency as the vibrator to be tuned, means for amplifying the said impulses, and translating means including a series of graduated test vibrators actuated by the impulses for visually indicating whether the vibrator being tuned is at or sharp.

2. In tuning apparatus for tuning a musical instrument having vibrators, the combination of a pick-up device vibrated sympathetically from the vibrator of the instrument that is to be tuned, said pick-up device operating to develop electric impulses at the same frequency as the vibrator to be tuned, a plurality of graduated test vibrators having a predetermined natural frequency, with an electromagnet corresponding to eachy test vibrator for vibrating the same, v said test vibrators including a vibrator whose natural frequency is that of the note to which the vibrator of the instrument is to be tuned, and including other test vibrators having natural frequency respectively above and below that of the said note, and

means for passing a current of said amplified impulses through the said electromagnets to enable the effect on the test vibrators to be observed.

3. In tuning apparatus for tuning a musical instrument having vibrators, the combination of a pick-up device vibrated sympathetically from the vibrator of the instrument that is to be tuned, said pick-up device operating to develop electric impulses at the same frequency as the vibrator to be tuned, a plurality of graduated test vibrators having a predetermined natural frequency, with an electromagnet corresponding to each test vibrator for vibrating the same, said test vibrators including a vibrator whose natural frequency is that of the note to which the vibrator of the instrument is to be tuned, and'including `other test vibrators having `natural frequency respectively above and below that of the said note, means for passing a current of said amplified impulses through the said electromagnets to enable the effect on the test vibrators to be observed, reflectors carried respectively by the test vibrators, and means for casting light onto the said reflectors.

4. In tuning apparatus for tuning a musical instrument having vibrators, the combination of a pick-up device vibrated sympathetically from the vibrator of the instrument that is to be tuned, said pick-up device operating to develop electric impulses at the same frequency as the vibrator to be tuned, a plurality of graduated test Vibra tors having a predetermined natural frequency, with an electromagnet corresponding to each test vibrator for vibrating the same, said test Vibrators including a vibrator whose natural frequency is that of the note to which the vibrator of the instrument is to be tuned, and including other test vibrators having natural frequency respectively above and below that of the said note, means for passing a current of said amplified impulses through the said electromagnets to enable the eifect on the test vibrators to be observed, reflectors carried respectively by the test vibrators, means for casting light onto the Said reflectors, and a screen in the path of the light beams reflected from the reflectors enabling the vibratory effects of the electric impulses on the test vibrators to be compared.

5. In a tuning apparatus for tuning a reed instrument, the combination of holding means for supporting the reed to be tuned and for vibrating the same, means for visually indicating whether the frequency of Vibration of the reed renders the reed sharp or fiat with respect to the true note the reed should produce, a movable member for engaging the supported reed to hold the same in a fixed position, and means including a tool for removing material from the face of the reed while held in the holding means, to alter its period of vibration.

6. In a tuning apparatus for tuning a reed instrument, the combination of holding means for supporting the reed to be tuned and for vibrating the same, means for visuallyindicating whether the frequency of vibration of the reed renders the reed sharp or flat with respect to the true note that the reed should produce, a movable member for engaging the supported reed to hold the same in a fixed position, a carriage movably mounted at the front of the reedI holding means, including a tool for removing material from the reed while held in the holding means, near its fxedend and near its free end, and means for controlling the tool.

7. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the plate, meansfor vibrating the reed to be tunedfa pick-up device controlled by the reed to vibrate at the same frequency as the reed, a visual indicator with means connecting the same with the pick-up device for indicating whether the reed is at or sharp with respect to the musical note that the reed should produce, means to be operated thereafter to hold the reed in a fixed position while held by the holding means, and means for removing material from the reed to increase or decrease its vibration frequency.

8. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the plate in a xed position, a pick-up device, pneumatic means for Vibrating the reed,

enabling the vibrating reed to control the vibration of the pick-up device and vibrate it at the same frequency as the reed is vibrated, a visual indicator with means connecting the same with the pick-up device to indicate whether the note made by the vibrating reed is sharp or flat, and means for removing material from the reed while held in the holding means, to increase or decrease its vibration frequency.

9. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of means for holding the plate, a suction box capable of communicating' with the air space adjacent the reed so that air may be drawn past the reed to vibrate the same and then into the suction box whereby the vibrating reed causes pneumatic vibrations of the air passing through the suction box, a pickup device associated with the suction box vibrated by the pneumatic vibrations of the air in the suction box, and a visual indicator with means connecting the same with the pick-up device to indicate whether the reed is sharp or iiat with respect to the note that the reed should produce.

10. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the plate, a suction box capable of communicating with the air space adjacent the reed so that air may be drawn past the reed to vibrate the same and then into the suction box whereby the vibrating reed causes pneumatic vibrations of the air passing through the suction box, a pick-up device associated with the suction box vibrated by the pneumatic vibrations of the air in the suction box, a visual indicator with means connecting the same with the pick-up device to indicate whether the reed is sharp or flat with respect to the note that the reed should produce, and means for removing a portion of the material of the reed While held in the holding means, toward its free end or toward its fixed end to change the frequency of the reed.

11. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the plate, pneumatic means for vibrating the reed, means for indicating whether the reed is sharp or at with respect to the note that the reed should produce, an abrading or cutting device aligned With the free end of the reed while held by the holding means, and an abrading or cutting device substantially aligned with the fixed end of the reed, and means for advancing either of said abrading devices to remove a portion of the material of the reed to alter its vibration irequency.

12. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the plate, pneumatic means for vibrating the reed, means for indicating Whether the reed is sharp or flat with respect to the note that the reed should produce, an abrading or cutting device aligned With the free end of the reed while held by the holding means, and an abrading or cutting device substantially aligned with the xed end of the reed, means for advancing either of said abrading devices to remove a portion of the material of the reed to alter its vibration frequency, and means for holding the reed in a xed position While the abrading tool is operating upon the same.

13. In tuning apparatus for tuning a reed instrument in which the reed is attached to a plate, the combination of holding means for holding the plate, pneumatic means for vibrating the reed, a visual indicator with means for controlling the same from the vibration of the reed to indicate whether the reed is flat or sharp with respect to the note the reed should produce, a carriage mounted in front of the holding means, with abrading or cutting means carried thereby for removing material from the face of the reed toward its ixed end or toward its free end, while the reed is held by the holding means, and means for backing up the reed at its rear face to hold the same fixed while the material on the face of the reed is being removed.

14. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the plate, means for vibrating the reed, means controlled by the vibration of the reed for indicating whether the reed is sharp or rlat with respect to the note that the reed should produce, a carriage mounted in front of the holding means, a pair of tools supported on the carriage aligned respectively with the free end of the reed and with the fixed end of the reed, and means for advancing either of said tools to remove material from the reed to alter its vibration frequency while the reed plate is held by the holding means.

15. In tuning apparatus for tuning a reed instrument in which the reeds are attached to a plate, the combination of holding means for holding the reed plate, means for vibrating the reed, means controlled by the vibration of the reed for indicating whether the reed is sharp or flat with respect to the note that the reed should produce, a carriage mounted in front of the holding means, a pair of tools supported on the carriage aligned respectively with the free end of the reed and with the fixed end of the reed, and means for advancing either of said tools while the reed plate is held by the holding means, to remove material from the reed to alter its vibration frequency including yielding means for pressing the tool against the reed lightly while the same is removing the material from the face of the same.

16. In tuning apparatus for tuning a reed instrument, means for vibrating the reed, a tool for removing a portion of the material from the face of the reed, with means for pressing the tool against the face of the reed including a yielding connection operating to press the tool lightly against the face of the reed.

17. In tuning apparatus for tuning a reed instrument, means for vibrating the reed, a tool for removing a portion of the material from the face of the reed, with means for pressing the tool against the face of the reed including a yielding connection operating to press the tool lightly against the face of the reed, and means for backing up the reed on the rear face while the material is being removed by the tool.

18. In tuning apparatus for tuning a reed instrument, supporting means for supporting the reed, a suction-box with a duct leading from the same to the air space adjacent the reed, a valve for controlling the communication between the suction-box and the reed so that when the valve is open, air will be inducted past the reed into the suction box thereby vibrating the reed and enabling the vibration of the reed to cause vibrations in the air in the suction-box, a microphone associated with the suction-box with an electric circuit passing through the same bearing a current having impulses produced by the microphone and corresponding to the frequency of vibration of the reed, means for developing an amplifled current from the first-named current, an indicator controlled by the amplified current for indicating Whether the reed is sharp or at with respect to the note that the reed should produce, and means for altering the reed While held by the supporting means, to increase or decrease its vibration frequency.

19. In tuning apparatus for tuning a reed instrument, a test box, a lamp associated therewith toward one end, a gang of graduated reeds mounted substantially in an arc toward the other end of the test box, said reeds graduated to vibrate at predetermined frequencies progressively from one end of the gang to the other, an electromagnet associated with each reed, a screen at the opposite end of the test box from the gang of reeds, reflectors carried by the reeds for reflecting beams respectively from the lamp onto the screen, and means for adjustably mounting each reed and its associated electromagnet to enable reflected beams from adjacent reeds to be cast adjacent to each other on the screen.

20. In tuning apparatus for tuning reed instruments, a test box having a lamp at one end of the same, a gang of reed frames with graduated reeds carried thereby disposed substantially in an arc at the other end of the test box, said reeds graduated progressively as to their frequency of vibration from one end of the gang of reed frames to the other, electromagnets carried by the reed. frames respectively for vibrating their corresponding reeds, reeotors carried respectively by the reeds, a screen at the end of the box adjacent the lamp, and means for pivotally mounting the reed frames to adjust the same so that the reiiected beams from the different reeds will be projected onto the screen adjacent to each other.

2l. In tuning apparatus for tuning a reed instrument, a test-box having a gang of reed frames, a gang of graduated reeds, each reed being carried respectively in its corresponding reed frame, said reeds constructed to vibrate at graduated frequency from one end of the gang of reeds to the other, reflectors carried by the reeds, means cooperating with the reflectors to cast light beams from the same, a base supporting each reed-frame, means for insulatingly supporting the said bases in the test-box to prevent vibration of any reed from effecting vibration of any other reed through said base, and electromagnets carried by the reed frames for vibrating the reeds.

22. In tuning apparatus for tuning a musical instrument having vibrators, the combination of a bank of test-boxes, said test-boxes corresponde ing to certain reeds of the instrument respectivei ly, a screen at the forward end of each box, a gang of test-vibrators at the back of each box', means for separately vibrating the different reeds of the instrument, means controlled by the v'ibrating reed of the instrument and cooperating With the test vibrators for indicating whether the vibrating reed is flat or sharp with respect to the note that it should produce, means for supporting the test-boxes in the bank with insulating means between the Walls thereof to prevent the vibrations of a test-vibrator in one box from affecting the test-vibrators of another box, and

means for insulating the test vibrators in each v box from each other to prevent interference between the same.

23. In tuning apparatus for tuning a musical instrument having vibrators, the combination of a pick-up device vibrated sympathetically from the vibrator of the instrument that is t0 be tuned, said pick-up device operating to develop electric impulses at the same frequency as the vibrator to be tuned, means for amplifying the said impulses, a test box corresponding to the vibrator of the instrument that is to be tuned, a lamp mounted at the forward end of the test box, a gang of test vibrators including an intermediate vibrator having substantially the same natural frequency of vibration as the vibrator to be tuned, and including test vibrators on one side of the saine Whose natural frequency gradually diminishes with respect to the said intermediate vibrator and including a set of test vibrators on the other side whose natural frequency gradually increases with respect to the intermediate test vibrator, an electromagnet corresponding to each test vibrator for vibrating the same, means for passing the amplified impulses through all of the said electromagnets and thereby causing vibrations of the test vibrators, reflectors carried respectively by the test vibrators for reecting beams from the lamp, and a screen at the forward end of the box upon which the light beams are projected from the reflectors.

24. In apparatus of the kind described for determining the true pitch of a note of a scale, the combination of means for producing an electric current having impulses of the same frequency as the sounded note, means for amplifying the current, and means actuated by the amplified current, and including a series of graduated test vibrators for indicating the frequency of the impulses of the amplified current.

VICTOR I-I. SEVERY.