US2045878A - Musical instrument - Google Patents

Description

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June 30, 1936. M 1 SEVERY 2,045,878

MUSICAL INSTRUMENT Original Filed July 15, 1951 5 Sheets-Sheevl 2 mventor.' kiwi/LL. Seya/y,

June 30, 1936. M. L. sEvl-:RY

MUSICAL INSTRUMENT Original Filed July l5, 1931 5 Sheets-Sheet 3 3nventor June 30, 1936. M- L. SEVERY 2,045,878

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MUSICAL INSTRUMENT Original Filed July l5, 1931 5 Sheets-Sheet 5 /74 772 summer; 7 7.7 7 7/ MUNI/ L- Gftornegs,

Patented June 30, 1936 UNITED STATES PATENT OFFICE MUSICAL INSTRUMENT Melvin L. Severy, Los Angeles, Calif., assignor to The Vocalsevro Company, Los Angeles, Calif., a corporation of Delaware Claims.

'I'he present application is a division of application Serial No. 550,987 filed in my name July 15th, 1931, this divisional application being tiled pursuant to official requirement.

This invention relates more particularly to a musical instrument having a plurality of tone qualities synthetically built up of suitably chosen and graded partials, each partial being produced in the air through the agency of a. pulsated electromagnetic eld including a movable member and a. coacting magnetizable member adapted to vibrate a sonorous element. It is not, however, restricted to such use, since the requisite pulsations may be produced through revolving commutators and brushes co-acting therewith, such as disclosed in my Patents No. 1,733,630 and` No.

An important object of the invention is the production of a musical instrument of one or more manuals, which is relatively cheap, compact, and durable, exceedingly powerful, exceptionally diversified as to tone, and of unusual artistic ca pabilities.

A further important object of the invention is the provision of multiplexed sonorous members,

each such member capable of responding at its own proper pitch when any one of a plurality of manuals is played, thus cheapening, simplifying, and greatly reducing the size of, the instrument.

A still further object of the invention is the provision of resonant means for the various octaves of the scale, especially adapted to the pitch and volume suited to that particular musical area of the instruments gamut.

:3.5 Another object ofthe invention is the production of an instrument, comparable in facility to the great organ, which shall possess throughout a true tonality not only as to its primes but as to all its partials, each and every partial being sepa- 4:.) rately produced under conditions particularly adapted to its own needs, and never sounding outside those cofnditions. v

Still anotherobject is the production of an instrument which, size for size, shall enormously .i excel the organ in volume, and which shall have as many tonal colors with greater facilities in their use, while possessing only a very small fraction of the parts necessary in organ practice. Furthermore, the instrument herein disclosed is La not sensitive to changes in temperature, and is free from tuning needs, up-keep difficulties, sluggishness of speech, impurities of tone, and inability to produce true soft tones.

In addition to the broader features of my invention there are special details of design and of structure, assembly, and co-action of parts which will be hereinafter explained.

An important object of my invention is to provide sensibly simple or fundamental tones having for each manual employed, the eighty-four 5 pitches associated with a seven-octave scale tuned in equal temperament. Where cheapness and compactness are vital factors, these same eightyfour notes may also be used, not only for the I`pitch-giving primes of all the tones of the instrument, but also, suitably proportioned as to loudness, for all of the other partials contained in its many varied qualities or timbres. This is what I denominate by borrowing system, and is disclosed in my Patent No. 1,899,884 dated February 28, 1933. Itis used in the present case because of its extreme simplicity and cheapness of construction, coupled with a musical efliciency remarkable in so inexpensive an instrument. It should be understood, however, that in more elaborate instruments I prefer to use a non-borrowing system wherein the Sounders used as primes are not at the same time used as upper partials, since this aords an even greater musical excellence albeit it is relatively more expensive and complex.

In musical instruments making use of a scale tuned in equal temperament, and depending for the musical pitches of such scale upon rotating members producing pulsations, all such pulsations, including those representing the well-known incommensurate ratios subsisting between certain notes of each octave, can be secured with an accuracy sufllcient for all practical purposes by the employment of rotating members having but six diierent rotative speeds for an instrument of a. range of seven octaves. More rotating speeds may be used, and in some cases twelve have been used, but for simplicity and cheapness, the smallest feasible number of speeds of rotation is preferred. For this reason use is here made of the general plan set forth in Patent No. 1,899,884, it being understood that where, in this present application, more than six moving members are shown, there are still but six rotative speeds, some of said speeds representing the velocities of a plurality of moving members. These moving members or rotors carry pulsation-producing toothed annuli, and are driven and governed in a manner essentially like that set forth in said Patent No. 1,899,884.

In the drawings:

Fig. 1 is a diagrammatic plan view of the driving and governing means for a three manual instrument, the three lowest octaves of each manual being served by three differently-speeded rotors, each of the rotors serving any manual revolving at the identical speed of the equivalent rotor associated with the other two manuals;

Fig. 2 is a side elevation, illustrating the grouping of the pipes about a rotor serving some of the -lower notes of the instrument;

Fig. 3 is a diagrammatic plan view of one 0f the three treble rotors of the instrument, illustrating the general scheme of arrangement r grouping of some of its Sounders;

Fig. 4 is an elevation, illustrating the same plan of grouping about the central rotor;

Fig. 5 is a sectional view of certain details of a sounder particularly adapted to the lowest octave of the instrument;

Figs. 6 and 7 are respectively, a plan view broken away, and a side view, of a multiplexed sounder especially adapted to serve throughout the range oi the second octave of the instrument;

Figs. 8 and 8a are respectively side and plan views of a sounder intended to serve the third and fourth octaves of the instruments range, that is, to and including note No. 49, only those parts necessary to a clear understanding of the device being shown in Fig. 8;

Fig. 9 is a side view of a sounder and its resonator, especially well tted to serve for the next octave of the instrument, that is, notes No. 50 to 61 inclusive;

Fig. 10 is a sectional side view of a sounder suited for the next to the last octave of the instruments gamut;

Fig. 11 is a side view of a sounder suited to the highest octave of the instrument;

Fig. 12 is a side view of a key of the manual, illustrating the key-contact systems used in an instrument having a plurality of manuals;

Fig. 13 is a diagrammatic illustration of the wiring system associated with one of the manuals, including also the tremolo mechanism;

Fig. 14 is an elevation showing details of a three-manual tremolo commutator;

Fig. 15 is a diagrammatic view of a wiring scheme adapted to a three-manual instrument.

Fig. 1 illustrates diagrammatically the placement of the rotors and the driving and governing mechanism for a three-manual instrument. It will be noted that the rotors serving the three lower octaves of the instrument are nine in number, the rotors for the groups of sonorous bodies indicated by the large numerals l, 2, and 3, serving, respectively, in these three lower octaves all the notes C,Ct, D and Dt; all the notes E, F, Ft and G; and al the notes Gt, A, At and B associated with one manual of the instrument, as, for example, the second or middle manual. Similarly, the rotors for the groups of sonorous bodies indicated by the large numerals 4, 5, and 6 serve respectively, the same notes of the three lower octaves of another manual, as for example, the upper manual; while the rotors for the groups of sonorous bodies indicated by the large numerals l, 8, and 9 similarly serve, respectively, the same notes of the remaining manual of the instrument.

Instruments of this type are conveniently divided into operative and speaking sections, and Fig. 1 is mainly concerned with the speaking part of the instrument. As the driving mechanism shown in this figure is clearly set forth and described in my Patent No. 1,899,884 above mentioned, and the governing mechanism is described and claimed in my Patent No. 1,911,326

dated May 30, 1933, only brief treatment of them is necessary here. A motor IB drives the belt pulley II through the agency of geared mechanism provided with a variable slippage factor consisting of a copper annulus I2 capable of retardation by the inductive action of the braking magnets I3, I4, the one constant and the other intermittent, the intermittent magnet being controlled by a centrifugal contact finger I5, and relay I6 and associated parts.

From the under side of the pulley II a belt I'I passes about the large pulley I8, thence under the adjustable, belt-tensioning idler I9 and about the large pulley 20. From the pulley said belt I1 passes to the larger pulley 2I, from which it passes about the pulley 22, thence about the angularly placedidler 23 and back to the upper side of pulley I I, thus completing its circuit. This arrangement serves to give correctly timed rotation to the three rotors driven by the pulleys 20, n

2I, and 22, said rotors not being shown in Fig. 1. These rotors serve the four upper octaves of the instrument throughout its three manuals, for since the Sounders for the higher pitches are so much smaller than those for the bass octaves, it is convenient to place about each of the three high speed rotors all of the Sounders associated with that rotative speed which are used in the thriceproduced scale of a three manual instrument.

In the three lower octaves, with their very much n larger Sounders, a similar grouping about three rotors is not convenient unless the largest sounders at least, are multiplexed, and in Fig. 1, for clearer showing, I have preferred to show a separate sounder for each of the three notes C, each of the three notes Ct, and so on throughout the lower three octaves of the instrument.

It should be understood, however, that where cheapness and ,compactness are suiliciently controlling factors, both may be obtained by the employment for the instruments lowest notes of the multiplexed sounders therefor which will be described later. The lay-out shown in Fig. 1 therefore comprises nine rotors for the three lower octaves of a three manual instrument, while the four upper octaves thereof are served throughout the three manuals by the employment of three rotors only. The three rotative speeds of the nine bass rotors shown are onefourth those of the corresponding treble rotors, and as clearly set forth in my Patent No. 1,899,884, each rotor bears pulsation-producing annuli adapted to generate at each revolution, sixteen, seventeen, eighteen, nineteen, or twice, four, or eight times such numbers of pulsations, thus producing, with the six rotative speeds, all the vibrational frequencies of seven octaves of a scale tuned in equal temperament.

In order to get the slower speeds necessary for the three lower octaves, a belt 24 passes from a pulley 25 to the rotor pulley 26 in the upper row of rotor pulleys, thence about an idler 27 and leftward to an adjustable, belt-tensioning idler 28. From the under side of idler 28 belt 24 passes about the pulley 29 of the rotor for group 5 in the middle of said upper row, and thence to the top of pulley 30 of the rotor for group 8 of said upper row. The belt 24 then passes to the pulley 3I of the rotor for group 'I in the middle row, from which it passes to the pulley 32 of the rotor for group 9 in the lower row; thence to the pulley 33 of the rotor for group 4 in the middle row; thence to the pulley 34 of the rotor for group G of the lower row; thence to the pulley for the rotor of group I; and thence to pulley 3B of the rotor for group 3 of the lower row, from the bottom of which it passes to the bottom of the small pulley 25, thus completing its circuit.

The resonant tubes of the Sounders associated with the rotor of group I are indicated at 36, 31, 38, 39, 40, 4I, 42 and 43. It is to be understood,

, however, that this showing could just as well represent either of the other two groups in this middie row, since they are all identical, merely serving identical notes of different manuals. Four electromagnets 44, 45, 46 and 41 are associated with sounders 36, 38, 40 and 42, the electromagnets associated with the other four Sounders being shown as broken away. The cores or said magnets project into close proximity to pulsation-producing annuli 48 carried by the shaft 49, one of which is shown but without teeth or wave forms owing to the smallness of its size and the fact that all these details are so clearly set forth in the patents before mentioned. They will also be brieiiy referred to again in connection With Figs. 3 and 7 hereof. A belt 50 extends from the pulley 25 to the tremolo-actuating pulley 5I, more clearly shown in Figs. 13 and 14.

As set forth in said Patent No. 1,899,884, the sizes of the pulleys are so planned with reference to the driving speed that the shafts carrying the lowest notes C of the instrument shall rotate at 121.25 R. P. M. (see group 4), while the shaft carrying the highest notes C shall rotate at four times that speed or 485 R. P. M. The bass shafts carrying the notes E rotate at 152.7654 R.v P. M. (see group and the treble shaft carrying the notes E rotates at 611.0617, while the bass shafts carrying the notes Gt rotate at 192.4723 R. P. M. (see group 3), and the treble shaft carrying the notes GII rotates at 768.8895 R. P. M.

In Fig. 2 the rotor or shaft 49 associated with group I of the Sounders is shown in dotted lines, the pulsatlon-producing annuli 48 carried by said rotor being also shown in dotted lines throughout most of its length. The electromagnets 45, 41 are likewise shown in dotted lines with their cores opposing some of the lower annuli on rotor 49. As shown in this figure, the resonant tube or sounder 36, as indicated by the numeral I preceded by the letter N, is designed to give forth note number I; sounder 31, note number I4; sounder 38, note number 3; sounder 42, note nurnber 2; and sounder 43, note number I3. Shorter resonant tubes 52, 53, associated with notes number and number 26, that is, note C of 129.33 vibrations per second and Cit of 137.02 vibrations per second, are likewise seen in this figure. The rotor 49 turns at 121.25 R. P. M., and carries all the notes C, Cif, D and Dt of the three lower octaves of the instrument commanded by one manual of the keyboard. The two other rotors associated with the same vibrational frequencies of the two other manuals of the instrument are identical with this and turn at the same speed. These three rotors of the middle row of the bass are so essentially like those of the other two rows serving the higher letters of the musical octave throughout the bass section of the three manuals, that no further consideration of them is deemed necessary. The resonant tubes are somewhat shorter and, as will be observed in Fig. 1, somewhat smaller of diameter as the pitches rise. The resonant tubes 39, and 4| of group I are associated respectively with note number I6, note number 4 and note number I5.

Figs. 3 and 4 illustrate in diagrammatic plan and in elevation, respectively, the grouping of the sounders about the treble rotor 54 revolving at 611.0617 R. P. M., said rotor carrying all the notes E, F, F# and G of the four upper octaves of the three manuals of the instrument, each note number shown in the drawing appearing three times, or once for each manual of the instrument. This is made possible without resort to multiplexing Sounders by reason of the fact that the higher pitches of the last four octaves can properly be served by much smaller resonant members. An annulus 55 with a small portion of its periphery dentated to illustrate the method of its co-action with the dentated head of the core 56 serving note 4I, is illustrated in Fig. 3. It is to be understood that the wave-forms or dentition of the annuli may be of any desired conformation, and may well vary even in the one instrument as between different sections thereof. To avoid annuli of undesirably large diameter and of objectionably high speeds of rotation where compactness is a vital consideration, it has been found desirable to use a wave-form so-called, having active portions or teeth somewhat resembling those of gears, but preferably with spaces between them occupying much greater peripheral extent than is occupied by the teeth or active portions themselves. It is also advantageous to curve or let off the peripheries of the teeth upon an arc of less radiusthan that of the annulus, all as set forth in the pat- 7 ents herein mentioned. Where a tonal result characterized by sine-wave type of vibration is desired, I nd it convenient where space and size are to be minimized, still to retain the gear-like type of active tooth", rounded as mentioned, 3J

and further to modify the result by the flexibly elastic member 51 or some equivalent, as will be shown in later figures hereof; by weighting to round somewhat the take-hold and letgo; and by the use, in most instances, of resonators as shown herein. In this manner sensibly sinewave simple tones are secured through the agency of annuli of practicable size even Where an annulus carries several scores of teeth or wave-forms. It is distinctly to be understood, therefore, that I do not confine myself to any particular shape of dentition or wave-form of the annuli, as that may be varied to suit conditions as aforesaid.

In Fig. 3 notes numbered 4I, 42, 43, and 44 are thrice exhibited, once for each manual of the instrument, their tubular resonators 58 extending upward as shown in elevation in Fig. 4. Below these notes are seen at 59 the radially outward ends of the shorter and diiferent type of resonators used for the thrice exhibited notes marked on the drawings N-53, N-54. N-55, and N--56.'

It will of course be understood that this rotor 54 serves vnotes not possible to show clearly in the drawings, each treble rotor of a three manual instrument of thisl type caring for sixteen notes thrice represented, or forty-eight in all. The housings 66 for the electromagnetic solenoids are indicated in dotted lines, the flexible support 51 for the radially outward end of a core carrying the plunger 51a co-acting with the oppose@ resonator being likewise shown in dotted lines. These members may be supported in any suitable manner, no such supports being here illustrated since it would unnecessarily complicate the showing of this gure. In Fig. 4 the annuli 55 are shown partly in dotted lines, all of said annuli in this figure being without wave forms or dentition.

Fig. 5 illustrates a resonant tube 6| suitable for use in connection with the lowest bass of the instrument. 'I'his resonator, where compactness is a considerable factor, may be multiplexed in the same manner as the Sounders illustrated in Figs. 6 and 7. It is desirable that the lowest notes of an instrument shall have not only very great volume, but also that they shall be capable of marked loudness of utterance, and this construction is directed to this feature. A diaphragm 62 of plunger type is suitably stiiened by ribs 63, and is elastically held in the casting 64 by an annulus or disk 65 of leather or other suitable material, securely clamped to said casting by an annulus 68 screwed thereto. 'Ihe flexibly elastic members G1, G8 which carry the plunger 62 are shown broken away, and their functions will be fully described in connection with Figs. G and 7. It will be noted that the casting 64 forms as it were 'a perforated floor for the pipe 6|, the upper side of the floor being at and in a horizontal plane, while the under surface with its opening 6Ia presents the conformation of the frustrum of an extremely obtuse cone, the purpose being to make'as eil'lcient a pumping mechanism as possible. The ribbed and leather-hung plunger 62 swinging upon the members 61, B8, and two other similar members not appearing in this figure, moves not as an ordinary diaphragm having its maximum motion in the center, but rather as a plunger with an equally wide movement throughout its area, thus producing a very great effect upon the air. The perforated floor 6e is shaped and placed so as to permit the most perfect evacuation of air feasible upon the lip-stroke, the slant of its lower side serving to prevent any choking action as the air from the outside area is forced into the smaller superficial area near the opening. This results in a pronounced amplification or" action and increase of loudness, a most desirable attainment in the case of the lower notes of the instrument, say from numbers Il to i3 inclusive..

`Referring now to Figs. 6 and 'i which show the same structure, the rotor d@ for group i oi the bass Sounders and an annulus it carried by the same are here illustrated, a portion of said annulus being dentated as shown opposite the dentated portion til of the cao-acting core. As shown in my patents before mentioned, and as indicated in connection with the description of Fig. 3 hereof, wave-forms or tooth-like dentitions of any desired shape may be employed accord-ing to the special exigencies of the case. The resonant pipe iii, plunger G2, and riios @i3 are also seen in Fig. 7. Bent metallic springs Gi, til, it, and il, broadest at the ends fastened to the pipe-supporting casting @fi and tapering toward their opposite ends, are secured in a somewhat interleaved iashion to the central stud 1li, this construction assuring the to-andfro motion oi' plunger 52. To the inner end of stud 'ld and Within the tube, a variable weight i5, shown in dotted lines in Fig. 'l'. serves to bring the whole system somewhere near resonance as well as to soften, as aforesaid, the sharpness of the pluck of the energized core when traversed loy the teeth oi an annulus leaning in type toward those of a gear. This weight it may be placed at any convenient part of the system, but, where room permits, it is Well to have it intimately associated with the plunge?, either inside or out.

A magnet rail li@ normally carrying time@ 501enoidal magnets 11, the central magnet being omitted in Fig. 6 but shown in section in Flg. 7, is supported at 18 as indicated by dotted lines in Fig. 7, the supports 18 being secured to the further side of the tube-supporting casting by screws 19. In Fig. 6 both the magnet-rail 16 and the rotor 49 are broken away better to show the structure and action of a'pivoted arm 80 upon the outermost bent metallic spring 10, said arm being secured to said spring at 8| by a link 82, the leverages being so planned that a given movement of its associated core shall give plunger 62 exactly the same traverse as will be given it by the same movement of either of the other cores acting upon it. 'Ihis pivoted arm 80 rocks at 83 between bearings 84 of the casting 85 secured at 86 to a boss 81 integral with the tube:-v supporting casting 64. The ring or annulus 66 securely screwed to the main casting with the plunger-supporting leather gasket 65 between it and said casting, is likewise shown in Fig. 7. A trunnioned member 89 rocks about a pivot 90, the threaded inner end of core 9| passing freely through this member, but being prevented from reciprocation by the lock-nuts 92 which serve to adjust the core nearer to or farther from its associated annulus for purposes of voicing. Spiders 93 having corrugated arms elastically support the dentated or rotor-end 69 of the cores 9| so that they may reciprocate freely without contacting their surrounding solenoidal tubes. Disks 94 (Fig. 6) which may well be of aluminum or brass, serve to cover the chambered portions of the magnet-rail occupied by the magnets, the free space 95 (Fig. 7) being usually lled with plaster of Paris or some suitable substance serving both to hold the bobbin rigidly and better to connect it thermally with the rest of the rail while electrically insulating it therefrom. This promotes cooling and keeps the solenoids more efficient, a method of procedure clearly shown in Fig. 10. Washers 9B are placed beneath the radially outermost ends of the spider-arms 93, through which and the disks 94 the spider arms are secured to the magnet-rail, their inner ends being securely fastened to and beneath the expanded core head as clearly shown in Fig. 7.

The parts omitted from Fig. 5 are identical with the corresponding parts of Figs. 6 and 7, but it will be noted that in Figs. 6 and 'l the resonant tube has no perforated floor but is stopped by the bodily-moving plunger 62, so that any amplincation of the tone in this instance is due to the fact that the leverages are so planned that the plunger t2, as shown, moves about two and a half times the distance traversed by the cores associated with it.

Referring to the two spidered cores 9i shown in Fig. 6, it will be seen that the ends of the cores farthest removed from the co-acting ann'uli reach the iiexibly elastic tapered members with which they are associated, and to which they are fastened, at a point to yield about the aforesaid inag- 1niication of movement, while the doubly compounded motion of the system associated with the arm 8U is such as to produce the same enlargement. The annulus d@ or Fig. 6, while the nearest to the observer of all the objects of the ligure, is shown in dotted lines to avoid obscuring inrportant members beneath it. The plunger-carrying annulus 65 of leather, rubber, or other suitable material is also seen in liig. 6.

The type of sounder seen in Figs. 6 and 7 is that which li nd suitable for a range of the bass ci the instrument extending from about note number 4 to note number 25 inclusive, and the pipe being multiplexed as shown, it may well be of large diameter and of great volume.

It will be seen from Figs. 5, 6, and 7 that while there are four elastically flexible, tapered, plunger-carrying members 61, 68, 10, and 1|, only three of them are energized by magnets when the greatest possible power is demanded. This four-support system, however, brings the active arms in better relation to the rotor than would a threearm system. The three magnets as shown are in line, though the center one is omitted in Fig. 6, better to show what lies beneath it. The resonators associated with notes numbers 26 and above, are of a size which will ordinarily permit the grouping of three of each note number, one for each manual, about their respective rotors, even where different manuals are not served in the bass by different rotors, as illustrated in Fig. 1 merely for the sake of clearness of showing.

The operation of the multiplexed pipes shown in Figs. 6 and 7 is as follows:

The three bent metallic springs 61, B8, and 10 are capable of energization by the magnets whose cores are attached to them either directly or through the pivoted arm 80, and the inner endsI of all four bent metallic springs are connected to the central stud 14 of the plunger forming the reciprocating floor of the resonator tube. When, therefore, the pressure of a key of a manual, as for instance, key number |3 of the first manual, acts through the operative system to energize its associated magnet, the result will be that the coacting core will be attracted and released by the alternate passage of relatively near and relatively remote portions of the revolving annulus opposing it. These motions will be transmitted through the associated bent, metallic spring to the plunger floor of the resonant tube, thus causing said tube to emit its proper note with an amount of loudness proportional to the amount of current flowing in the energizing coil about the active magnet-core. If at the same time, the same note, number I3, of either or both the other manuals be pressed, care having been taken that the centers of the teeth of all cores thus associated in the multiplexing of a sounder shall simultaneously pass the centers of the teeth of their coacting annuli, the associated core or cores will be energized proportionally to the current flowing about them. The associated bent metallic spring or springs will then transmit the energy to the plunger, the result being that the plunger will make longer excursions the more power it receives.

As the energizing solenoidal magnets of a multiplexed pipe are each upon a circuit controlled by a separate manual, it will be seen that a pipe so multiplexed may perform all the functions of three pipes speaking at the one pitch and controlled by three separate manuals, for the sounding of a pipe through pressure of a key of one manual is no bar to any desired simultaneous sounding of the same. pipe in response to pressure of the corresponding key of another manual.

Considering now Figs. 8 and 8a, which are two views of the same structure, Fig. 8a showing only such parts as are necessary to a full interpretation of Fig. 8, the housing 12 for the solenoidal magnet (shown in dotted lines), is provided with a flange seen at 12a. The metallic C-spring 91 is screwed to this flange, and to the free end of said spring is fastened the casting 98 carrying at the rightward end the ribbed circular plunger 62 adapted to beat air into the resonant'tube 6|. This plunger is secured to the casting 98 by a threaded stud 99 carrying weighting washers |00 of lead or other material, secured between two nuts It is to be understood that while a system of vibration which is more or less forced requires nothing for its mechanical movement in the way of Weighting or tensioning which would satisfy the exacting needs of musical tuning, yet, notwithstanding this rather wide workable latitude, the nearer true resonance is reached in a system, the greater will be its efficiency and the less forcing it Will need, a fact which explains one important reason for using weights and proportioning the springs to the work in hand. The resonator tube while it will respond throughout a rather Wide range from the standpoint of tuning accuracy, should be proportioned with care to the pitch of the note it produces, in order that its utterance may be sensibly perfect. This system of tone production must not be confused with organ practice Where the pitch as well as the quality of the tone is determined by the pipe, for here the pitch is determined outside the pipe, and the quality is made in an entirely new manner. If the resonator does not suit the pitch delivered to it, it will have to be forced, and will speak less and less efficiently the more it has to be forced.

A screw 88 (Fig. 8) is threaded into the lower` end of core 9|, which is slit for a little more than the distance of the thread in order to prevent possible rattling. This screw 88 passes freely through the swinging member |02 which is pivoted upon threaded centers formed on the screw |03 adjustably and securely held in the casting 98 by the check-nuts |04. A threaded thumb-wheel |05 together with a nut |06, serves to position and secure the screw 88 relative to the swinging member |02 and the casting 9B, thus serving to adjust the core 9| with regard to its co-acting annulus (not shown in Figs. 8 and 8a).

It will be noted that the casting 98 serves both as an amplifying extension for the C-spring 91,

and as the major part of the weight necessary to ease off the attack and let-go where a gearlike form of annulus-tooth is used and an approximately sine-wave form of result desired at the plunger 62. 'Where this resonator will do the rest, delivering a full and beautifully formed simple tone. This type of sounder, with its relatively large resonator and considerable amplification, is well suited to meet the requirements of the highest of the three bass octaves of the instrument, as well as the lowest of the four treble octaves, covering in all notes No. 26 to No. 49 inclusive, the plunger and resonator sizes being progressively diminished as the pitches rise.

In Fig. 9, 12 indicates the housing of the solenoid; 9| the core which as seen at 69, has five dentitions or wave-forms where Fig. 8 shows but three, while Fig. 11 shows six, the explanation being that, as the pitch of notes rises, the wave-forms or teeth are more numerous and nearer together, thus permitting more teeth within the normal space of an enlarged magnet-head. The spiders 93 shown and described in connection with Figs. 6 and '7, and seen also in Fig. 8, are likewise illustrated in Fig. 9. A bent metallic spring |08, preferably of soft steel that it may not retain magnetisrntyet may afford a good path for is secured the the return lines of force, is secured at its ends to the longitudinally-extended ilange 12* of housing 12, the mid-portion of said spring being secured to the lower end of core 9| which passes through the riveted portion |09, and into thecentral stud of the ribbed plunger 62. An adjustable weight ||0 is attached to the core for purposes already clearly set forth. A resonator 6| is shown broken away, to indicate that it may be of any desired length suitable to the different notes served by the various Sounders of this type, which type I nd Well adapted to notes numbered 50 to 61 inclusive. The spring |98 is held at both ends, thus making it somewhat less resilient and better suited to vibrations ranging from 548.07 to 1034.61 per second. The notes being of relatively high pitch, do not require a loudness which necessitates mechanical amplication.

Referring now to Fig. 10, the housing 12 fo the solenoidal magnet 11 is shown as embedded in an insulating material 95, as previously mentioned in connection with Fig. 7. The core 9|, spider 93, and associated parts are also illustrated in Fig. 10, the core head 69 in this instance carrying five narrow teeth intended to oppose an annulus with the considerable number of teeth necessary for so high a pitch as this type of sounder is designed to serve. The flange 12a of housing 12 is circular in plan, and is adapted to receive the circular and annularly and concentrically grooved member which is iirmly clamped, diaphragm-wise, between said flange 12EL and the metal retaining ring 13, which may be of lead so that it may damp the peripheral vibration of the grooved member, concentrating the same, as much as possible, at the thickened innermost area carrying at its center the reduced and threaded end |I2 of the magnet core. Metallic washers ||3 permit the nut ||4 to bind the said innermost area firmly between itself and the shoulder of the magnet core. ||5 indicates disk lamin used for weighting, and secured to the core end ||2 by a nut IIB. The grooved member may be of any suitable material, but I have found a good grade of maple to serve excellently where a simple fundamental tone is desired, as in this case, for even were there faint upper partials, they would be so evanescent as not to be objectionable where wood is used. To

ensure the necessary fundamental quality, the member is left thick at its center that it may vibrate as a plunger, rather than breaking up as a diaphragm might do. This type of sounder is excellent for notes extending from No. 62 to No. 73 inclusive. As these pitches are so high, resonators may ordinarily be entirely dispensed with, the area of the Vibrating member furnishing volume quite suilicient for tones which are so incisive.

Fig. ll shows a construction similar to that of Fig. 10, the magnet flange 12a being entirely circular in plan but much smaller, and a relatively short, six-toothed magnet core 9| suitable to the highest pitches of the instrument being illustrated. The lower end of this core is shouldered and thrust through a diaphragm i l1, to which it is securely attached by the nut i I8, the weighting lamin ||5 and securing nut I6 being also shown. The diaphragm H1 is of any suitable material, a ring I9 which may well be of metal as soft iron, being provided to facilitate return lines of force. Screws |29 clamp diaphragm H1 in place. By making the diaphragm of soft steel the resistance of the magnetic circuit will rbe greatly lessened, permanent magnetization being avoided, while any upper partials that might be present are so high in pitch as to cause no inconvenience'whatever. This type of sounder is designed for the highest octave oi. the instrument, that is,4 from notes No.. 74 to No. 84. These pitches, the lowest of which represents 2,192.26 vibrations per second, are so acute as to require a relatively small volume to enable them musically to balance the lowest notes of the instrument, so that the diaphragm of small diameter is of suilicient area, due reference being had to the scale used in the drawings which, in the case of Fig. 11 is approximately one-half size, though I do not of course', limit myself to particular sizes, actual or relative.

Fig. 12 illustrates a slightly modiiied form of 1,', the key-action shown in my Patent No. 1,899,884 and described in detail therein. The key-bed |2| is provided with longitudinally extending raised portions |22, |23, from which pins |24, |25 extend upwardly and serve to position or space the 2C) keys with regard to each other, in the well-known manner. 'I'he essential difference between this gure and the construction of my Patent No. 1,899,884, just referred to, is the additional multicontact block and its associated parts, made nec- .l essary because of the plurality oi manuals used with the present instrument. A white key of the manual is indicated at |26, the felted key-strip |26a limiting the upward movement of the keys under the urgency of spring |21. A projection 30 having a screw-eye passed through it, and an adjusting leather nut, are provided at the rear of each key for the purpose of tensioning spring |21, the lower end of said spring being looped about a slanting notched dowel |21 glued into the rear of the key-bed.

Tongue springs |28, |29 are screwed to said key, these springs being regulated as to their degree of depression by the adjustable screws |30, the shouldered lower ends of said screws passing 40 through the key as shown. Multi-contact blocks |3| are screwed to the key-bed beneath each key, each block being grooved to fit over longitudinally extending positioning strips |32, |32, which serve to keep pressed upward in passive position 45 the wire tongues |33 serving as contact members. Current is supplied by cables |35 to the wires passing through the wiring strips |34. A continuous metal strip |343L serves as a common lead or return, as the case may be, since it is immaterial which purpose it serves if other conditions are suitably adjusted. The contact wires from tongues |33 are bent upwardly at their righthand ends to facilitate Wiring into the cables |35 or onto the continuous strip |34a. One similarly disposed wire of each block |3| is joined to said strip as seen in Fig. l2, the connection being parted to avoid confusion in the drawing and the open ends thereof being indicated at |34b, |346, respectively.

The tongue springs |28, |29, each carry at their lowermost ends a contacting strip |93, |94, preferably of silver, long enough, transversely to the keys, to bridge safely all of the associated contacts |33 lying beneath them, to the number of four in each case. Of these two systems of four contacts, one contact in each case serves as a common return as described in said Patent No. 1,899,884, the other three contacts in each case 73 being wired to the other sides of appropriate magnets in the operative system as later described. 'I'he essential point in connection with Fig. 12 is that in this instrument each of the keys of each of the manuals is provided with T5 Cil eight contact-systems, two of which are used as returns.

Fig. 13 illustrates in its upper portion what is termed the partial-mixing system, as applied to a single manual and its associated speaking magnets, each as shown and described in my Patent No. 1,899,884, but in this instance the tremolo system for a single manual has been added to render more easily understood the system applicable to a plurality of manuals as shown in Fig. 14. |36 (Fig. 13) indicates the speaking magnets, each of said magnets having associated with it the number of the note of the gamut which it controls. Thus the extreme left-hand magnet |36 in this figure controls note #I the magnet to the right thereof, note #|2, the next magnet to the right, note #|3, and so on. Associated with each pair of magnets |36 is a resistance |38. The bar |3'|, assumed in this showing to be movable transversely of its length, affords means for positioning the contact tongues |38a along the resistance coils |38, thus diagrammatically representing the electrical result attained by the various partial-rockers indicated at |39.

In the center of Fig. 13 are three vertical rows of block-like members with ten blocks in each row, placed wide apart to permit showing the wiring, the central row of said blocks being doubly tipped with silver so that the blocks may contact properly on both sides. The left-hand row of ten contacts in Fig. 13 is brought into electrical connection with the opposing co-acting surfaces of the central row of contacts when key #I3 of the manual is pressed and the partialrocker |39 representing the first partial is in operative position. Similarly, the right-hand row of ten contacts is brought into electrical connection with the opposing co-acting surfaces of the central row of contacts when key #I4 of the manual is pressed. Since a seventh partial is omitted in this instrument as shown, a graded sub-octave taking its place, and because it is more orderly to start the moving contacts with the sub, it will be noted that the first partial is crowded up to the second moving contact in each row. It will be seen, therefore, that each speaking magnet |36 (which in shop practice is always designated by the number of the key of the manual normally causing it to speak when such key is pressed) is wired, as shown, from its nearer pole to the second contact of the associated side of a double relay bearing said manual note-number, such double relay bearing a number in accordance with the control of its two actuating magnets by two separate adjacent keys of the manual, as fully explained in my said Patent No. 1,899,884.

In order to make clearer the showing of Fig. 13, directions for the wiring of each contact have been noted opposite the outside contacts of the double relay. It will thus be seen that every such contact save only the second in each outside row, invariably sends a wire to an outside second contact of some other double relay, which is always treated with regard to its numbers in such wiring as if it were two single relays of adjacent numbers. To make it clear to which relay thev second of each of these contacts is wired, the note number, which is to say the relay number, is indicated on the drawings, together with the letter of the octave representing the note and the number of vibrations normally elicited by the pressure of the similarly numbered key of the For example, considering the left side manual.

of the double relay in question, which is designated relay #|3, the contact marked 2 is for a prime or rst partial having 64.663 vibrations per second, represented on the manual by the note C. The next contact marked "3, therefore, will be for the second partial which, being of twice the number of vibrations, represents the note C an octave higher having 129.326 vibrations per second, and associated with the twenty-fifth note of the manual. This third contact will accordingly be wired to the second moving contact of relay #25, the outside rows of contacts of a double relay being thus referred to as moving, All of the other contacts of the outside rows are similarly wired, it being obvious that in the case of the double relay #|5, #|5, the numbers applying to relay #I5 will be just one number higher than those applying to relay #Il in similar cases. The same procedure will apply to relay le so that the entire relay wiring of the instrument may be set down from a consideration of what obtains in the case of one relay, even though it were not a double one.

In the central row of contact tongues in Fig. 13 each of said tongues is to be understood as wired, though not so shown in the drawings, to two adjacent notes upon its associated partial-mixing rocker |39, after the manner clearly set forth in said Patent No. 1,899,884.

|40 leading to a rheostat |4| of the particular partial-rocker reserved for this sub, forty-two wires |40 being provided for an eighty-four note instrument, as indicated in the drawings. From the central contact marked 5 a wire |42 leads to a rheostat 4|, the other end of said resistance being connected to a'contact tongue |43 serving upon the fifth partial rocker, the fortyrst and forty-second notes of the manual. It will be observed that there is another fifth partial rocker |39' and another resistance |43 in parallel with the resistance |43 serving the partial rocker just described, and these two resistances may be of any desired ohmic value. If, therefore, the first described fth partial-rocker be actuated, the loudness of the fifth partials will be determined by the ohmage of the resistances |43, while if rocker |39 is actuated, the resistances |43' will determine the loudness.

another loudness will result from the simultaneous use of the two resistances and the two rockers, as will readily be seen, three diierent loudnesses of the fifth partial with two rockers and their associated resistances being thus obto the degree of the pressure, shall connect said brushes irrespective of the angular position of the commutator upon which their rightward ends rest. 'Ihe result is that when section |41 of said commutator passes under the brushes they are short-circuited and the resistance of the line at For example, the n tongue marked Sub in the drawings has a wire If both these rockers be actuated together, still this point rendered negligible, while, when the commutator reaches the position shown in the figure, theresistancc of such portion of the coil |48 as the movement of the knee-swell does not cut out, will be inserted into the line at this point. The knee-swell |46 is positively positioned against a stop |49 by a spring |53, which causes the bifurcated brush having one prong so-mewhat longer than the other, to rest wholly upon insulation at the right-hand end of drum |52 carrying the coil |48, this coil being traversed by brush |5| when the knee-swell is operated. The pronged brush |5| is carried by a flat slidable bar |53 running in graphited felt bushings, said bar having secured to its leftward end a flexible wire connection |54. Another connecting wire |55 is secured to the leftward end of the helix or coil |48, this wire being suitably secured to the box containing the drum |52 by a binding post or equivalent means. A link |56 serves to connect bar |53 with the innermost extremity of the rod of knee-swell |46.

A flexible contact spring |51 is secured to the left end of the box which houses the resistance drum |52, the left end of helix |48 and of wire |55 being secured to this contact spring. To insure perfect and correctly timed contact, the contacting end of spring |51 is adjusted relative to its coacting contact by a screw |58 passed through an opening in the spring. An angularly bent member |59 is secured to the slidable bar |53, and pushes the flexible contact |51 slightly to the right as member |58 contacts with said tongue under the action of spring |50, thus shutting off the tremolo upon the removal of the players knee, and cutting out the resistance nelix irrespective of the position of the revolving tremolo commutator.

'I'he alternate high and low resistance of the line at this point produces a shake or tremolo in the tone, more or less pronounced according to the position of the knee-swell. It is to be understood that in the three manual instrument forming the basis of this application, Fig. 13 applies to each of its manuals, except that the three tremolo commutators may well be on the same shaft and propelled by one pulley. 'Ihis arrangement is illustrated in Fig. 14, where the manuals are indicated by the roman numerals I, II, III, and three pairs of brushes |44, |45 associated with the three commutators, are shown.

Fig. illustrates diagrammatically the speaking magnets and their associated parts, as described in my Patent No. 1,899,884, rendered applicable to a three manual instrument. The speaking magnets .rst manual of the instrument, while the magnets |60 are associated with the operative system of the same manual. The magnets |363, |60a are associated respectively with the speaking and operative systems of the second manual of the instrument, while the magnets |36b and |60b are associated with the speaking and operative systems of the third manual of the instrument. The common bars |31, resistances |38, contacts |382 and associated parts, serve to illustrate the action of the expression-control sytems of the three manuals, these being but reduplications of that shown and clearly described in detail in said Patent No. 1,899,884. To avoid a confusion of wires, only the circuits of the speaking magnets are fully shown, those of the magnets of the operative systems being indicated by plus and minus signs. These magnets are those associated with the same four keys, as for example #i 3, i 4 #15,

|36 are associated with the.

#|6, of each of the three manuals, and as shown at IBI the speaking magnets are connected together in pairs on one side. Similarly, the central relay contact |62 of each relay serves for both members of its pair of associated speaking magnets, as clearly set forth in my aforesaid patent. Manual keys |63, |64 of each of the three manuals representing notes #|3, and #I4 are associated in a pair in each case as aforesaid. The pedal keys |65, |66 correspond to keys #I3 and #I4 of each of the three manuals when the instrument is "multiplexed as shown here. The outside relay contacts |61, |68 are connected respectively to one side of speaking magnets |36, forming a pair. As shown in Fig. 13 the relay contacts |62, |61, |68 are but three of a contact system having for each relay thirty contacts, that is, three rows of contacts as shown, but ten deep in a direction not convenient to show in this View.

The electrical placement of the three tremolo systems is schematically shown at |69, |10, |1I, each of said devices being essentially like that shown in Fig. 13 with slight modification as indicated in Fig. 14. The partial resistances |4I are more fully shown in Fig. 13, this gure being s'carcely more than a multiplication of the system applicable to a single manual of the instrument, with the addition of keys for a pedal bass.

|12 indicates a source of current and |13 a wire leading from the negative pole thereof. A wire |14 leads from' the positive pole of said source and branches into three wires before entering the tremolo system. Positive wires |15, |16, |11

emerge from the tremolo system and pass ref spectively to the three common wires |18, |19, |80 of the three partial rocker systems serving the three manuals.

The operation of the system is as follows:

Suppose key #I3 of manual I be pressed, causing which only one (associated with this relay) ap- 1 pears in the drawings. Current then flows from source |12 through wire |13 to the expressioncontrol member |b associated with the common bar |31 for manual I; thence through the resistance to the branching circuit at |6|, whence wires t.'

lead to speaking magnets |36 associated respectively with notes #I3 and #I4 of the first manual. As only the contact block |61 associated with the upper magnet is electrically co-acting with its associated central contact, from which the rest of the circuit via the partial resistance I4|, contact member |83, common wire |18 and wire |15 back to source |12, is supplied, only the note associated with the speaking magnet for note #I3 of the rst manual sounds, which it does with a quality determined by the mixing system, and a loudness determined by the expression-control system. If, now, the pedal bass key |66 associated with note #13 of manual I be pressed, negative current flows from' its across the contacts |84, |85, to the self-same magnet of the operative system, the other pole of which is Wired to the positive side of the source of current. This energizes said magnet |60,

which then acts precisely as before and with the CFI same result. Fig. 13 embodies a schematic representation of a system based upon the use of the multiple relay shown in Fig. 22 of said Patent No. 1,899,884. It is obvious, of course, that the type of relay shown at Fig. 20 of that application might be used, but for compactness and cheapness of construction I ordinarily prefer the multiple type herein indicated.

I wish to make it clear that in a powerful instrument of the kind herein set forth, a properly worked out scale dictates, if the best results are to be attained, frequent changes in the type of sounder as the pitch of the notes served by the Sounders rises, permitting the volume of the tones to be decreased according to the well-known values subsisting between high and low tones. For this reason I have thought it expedient to illustrate these most desirable types, and to indicate the ranges of tone over which each may well be used, though of course I do not limit myself to the specific types of Sounders herein illustrated and described nor to the precise ranges given as the limits are naturally somewhat elastic, a few notes either way not being fatal, even if not giving the most ideal results, and I consider these various sounders an integral part of my invention.

There is still another advantage of my system of tone-production too important to be overlooked. So far as I am aware all other keyed instruments now in use are tuned in equal temperament as to their primes, and owe their timbres to these primes being associated with certain other partials which are not tuned in the same temperament and do not, therefore, produce ideally smooth results. In my system, however, all the upper partials as well as the primes of all tonal qualities are in the one temperament, thus leading to a perfection of result rot otherwise attainable. .As every sounder used is planned for service as a prime, and is only called upon to produce one simple tone at the one pitch, notwithstanding its use for upper partials in tones having primes below this pitch, it is possible for the first time in keyed instruments, so far as I know, to produce tones of any conceivable composition, all of whose partials are perfectly formed, chosen, and graded entirely at will, and without those limitations which have heretofore beset makers of musical instruments.

While the pulsation-producing members 48 are shown as annuli, and will preferably be made in annular or ring form, it is obvious that they may be complete disks suitably separated from one another and permanently united to form an extended rotor.

I do not conne myself to the particular manner of initiating tone herein shown, nor to this exact way of controlling tone color or timbre, since any means of producing a plurality of sets of repetitious impulses all in one temperament and of simple wave-form, selecting these sets as to order, grading them as to relative prominence, and using them as all the components of compound tones of various timbre, I hold to be well within the scope of my invention, and I have elsewhere shown several other ways any of which, suitably designed, might be similarly used in the broad combinations herein claimed.

No claim is herein made to the multiplexed instrument per se, the same being reserved for and claimed in my said application Serial No. 550,987, led July 15, 1931.

What is claimed isi- 1. A musical. instrument for producing compound tones the upper partials of which are all in the same temperament as the first partials or primes, said instrument comprising means substantially such as shown and described, for separately generating individual pulsations of simple sine-wave form and equal temperament; and means for selecting andv combining into a composite tone of desired quality any of the pulsations so produced.

2. A musical instrument for producing compound tones with primes or first partials and upper partials in equal temperament, the same comprising, in combination: means for separately 'generating individual pulsations of simple sine-wave form and equal temperament; means for selecting desired pulsations; and means for combining the selected pulsations into tones of the desired pitch and quality.

3. In a musical instrument, means for pro-- ducing compound tones the upper partials of which tones are all in the same temperament as the first partials or primes of said tones, and including means whereby each compound tone is produced through the impress upon the air of sets of repetitious impulses of different frequencies as between sets, each said set and frequency being individually generated and of sensibly simple wave-form.

4. In a musical instrument, means for producing compound tones, the upper partials of said tones being all in the same temperament as the first partial or prime, and including means whereby each partial of each compound tone is separately produced by the generation of its proper sensibly simple wave-form; and means for synthesizing the component wave-forms into a tone of the desired timbre.

5. In a musical instrument, means for producing a. compound tone the upper partials of which are all in the same temperament as the first partial or prime, and including means whereby each partial is produced through individually generated sets of impulses of sensibly simple wave-form; and means for synthesizing' all of said partials to produce said compound tones.

6. In a musical instrument, means for producing a compound tone of predetermined quality, the upper partials of which are all in the same temperament as the first partial or prime; means for selecting and grading each partial as to relative prominence in accordance with the timbre desired and including means whereby each partial is produced by individually generated sets of repetitious impulses of simple wave-form;` and means for synthesizing all of the partials to produce the desired tone quality.

7. In a musical instrument, means for producing compound tones, the partials of said tones being all in one temperament, and including means specially designed for individually generating a set of simple, repetitious impulses of predetermined, constant periodicity and sensibly1 simple wave-form to be used for each and every partial, within the lnstruments range, characterized by the said periodicity.

8. In a musical instrument, in combination, generators producing pulsations of sensibly simple wave-form and of all of the periodicities of the tones used throughout the instrument, said pulsations being all in the same temperament with respect to each other; manual keys, or

equivalent means, for initiating, upon their actuation, the conversion of said pulsations into audible sounds; instrumentalities, under the control of the performer, for predetermining the timbre of the tones to be elicited; switchingmeans, operable by the finger-keys of the manual and co-operating with said instrumentalities, for selecting and rendering effective, in the case of each key operated, just those periodicities of pulsations necessary to be synthesized for the predetermined tonal result; and means for segregating as to order and regulating as to relative prominence, all the partiels simultaneously used, thereby producing at will compound tones of the timbre desired the partials whereof are all sensibly in the one temperament as to periodicity.

9. In a musical instrument, in combination, formed, timed, rotating members and magneticflux-varying means associated therewith; pulsation-producing means operated by the flux-variation and serving to convert mechanical motion into sound, each said magnetic-flux-varying means producing sets of repetitions pulsations of sensibly simple wave-form in equal temperament with respect to the others, and thereby generating tones all the components of which are in v the same temperament.

10. In a. musical instrument, means for generating partial-producing impulses of sensibly simple, sinusoidal wave-form by individual instrumentalities, all said instrumentalities producing in operation sets of repetitious impulses in the same temperament as to periodicity.

11. In a musical instrument, individual instrumentalities adapted to generate partial-impulses of sensibly simple Wave-form, all said instrumentalities producing in operation sets of repetitions impulses in the same temperament as to periodicity, and means for selecting, as to their order and relative prominence, the sets of partial impulses to be simultaneously employed.

12. In a musical instrument, in combination, formed, timed, rotating members and magneticflux-varying means associated therewith; pulsation-producing means operated by the flux-variation and serving to convert mechanical motion into sound, each said magnetic-fiux-varying means being individual to some one periodicity of the instrument and producing pulsations of sensibly simple wave-form in equal temperament with respect to the others, and thereby making possible desired timbres all the components of which are in the same temperament.

13. In a musical instrument, in combination, a plurality of means for generating individual sets of timed, repetitious, partial-producing impulses of sensibly simple Wave-form, and of periodicities all of which are in the same temperament; and means for simultaneously employing a plurality of diierent sets of said repetitions impulses to produce compound tones.

14. In a musical instrument, in combination, a plurality of means for generating individual sets of timed, repetitions, partial-producing impulses of sensibly simple wave-form, and of periodicities all of which are in the same temperament; and means for selecting as to order, grading as to relative prominence, and simultaneously employing a plurality of different sets of said repetitious impulses to produce compound tones.

15. In a musical instrument in which the upper partials as well as the primes are in the same temperament, and in which the vibrations producing the individual tonal components are of sensibly simple wave-form, means for prevent-A ing the intrusion into said components of all impulses which would destroy the simplicity of their wave-form.

16. In a musical instrument in which all the partials are in the same temperament and in which the vibrations producing the individual components are of sensibly simple sinusoidal wave-form, means for restricting these components each to sets of repetitions vibrations of a sensibly simple wave-form and of a periodicity determined by the order of said component and the pitch of the tone of which it is to form a component.

17. In a musical instrument in which all the partials are in. the same temperament, a keyboard, and separate means, each responsive to a key of a manual thereof, to produce sets of repetitious impulses of simple wave-form, the periodicities of all of the said sets comprising the periodicities of the primes of an instrument of like gamut when tuned in equal temperament; and means for selecting, grading and simultaneously using desired sets of these impulses in the production oi compound tones with all their upper partials as well as their fundamentals or primes, in equal temperament.

18. In a sounder adapted to the bass tones of a l musical instrument, a resonant chamber; a vibrating member associated therewith and adapted to set up sonorous Waves therein; means for bringing the natural periodicity of said vibratingl member into approximate resonance with the note it is intended to serve; and a plurality of means, one or all of which are operable at will, for delivering correctly-timed impulses to said vibrating member.

19. In a sounder adapted to the middle range of a musical instrument, a resonance chamber;l a member opposing and near to an opening of said chamber and adapted as it reciprocates, al-

ternately to beat air into and to suck it from 4 the chamber; a spring having an extension by which said member is carried; a magnet core attached to said spring; means for bringing all the moving parts of said sounder into approximate resonance with the pitch of the note it is intended to serve; and rotative means, rendered operable at will, for causing the longitudinal reciprocation of the magnet core, the spring and the a rhythmical to and fro movement of said core, C

spring-center and reciprocative member, and thereby causing said member to beat air into and suck it from the resonance chamber and to produce a tone of a pitch characterized by the periodicity of movement of the magnet core.

MELVIN L. SEV'ERY.

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