US2482646A

US2482646A - Method of and means for treating clubfoot

Info

Publication number: US2482646A
Application number: US641676A
Authority: US
Inventors: Philip R Brachman; Orville C Sonntag
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-01-17
Filing date: 1946-01-17
Publication date: 1949-09-20
Anticipated expiration: 1966-09-20

Description

p 1949 I P. R. BRACHMAN ET AL. 2,482,545

METHOD OF AND MEANS FOR TREATING CLUBFOOT Filed Jan. 17, 1946 Patented Sept. 2Q, 1949 METHDD "OF MEANS FOR TREATING oral-#1 CE RaBr-achman and Orville G. Somltag,

Chicago,

Application January 17, I946,1Serial No. 641,676

' (01. us -s0) 13 Glaims. 1

This invention relates to the treatment of talipes or olubioo't and more hartisnlarly to apparatus for the treatment thereof.

An object of the invention is the provision of novel and improved apparatus adapted to minimine, if not to obviate, the necessity of using nocomfortable, unsightly and more or less inimobilizing casts or splints hitherto employed after the usual -preliminary corrective manipulation of deformed ieet. I

Another object of "the invention is the rovision of such apparatus "whioh, while permitting independent and comelated foot movements about axes substantially parallel to'tlhe legs beto each other in a manner simulating walking.

Another object of the invention is' the provision of such apparatus which, while hreventing movement of a deformed root between an improved positien and the deformed position, permits exercising the foot and leg by movements thereof outside the range between the deformed and improved positions.

The invention as a 'rfurther object the provision of such apparatus whioh is readily and easily applicable to and removable from the feet 2 a of a user.

Yet another object or the invention is the provision of such :appamms having an adjustable prescription angle; 5. e., the angle defined by the longitudinalaiies or center lines of the feet of a user in a prescribed improved hosition and from which neither toot alone is movable "toward its deformed position.

Another object of the invention is the ':-provision of such apparatus wherein the presentation angle is variable sul-ficiently to adapt the apparatus for the treatment of talipes of the type wherein the forward ends of the feet are turned outwardly relative to each other andof the type wherein they are turned inwardly toward converging relationship.

A further object of the invention is the provision of such apparatus wherein :a pair of shoes is removably attached to connecting "means adapting each shoe of the for limited relative pivotal movements about a eenter at the sole of that moving shoe and about a center at the sole of the other shoe.

Other objects of the invention will be apparent from the following description and the encoma 2 partying drawings disclosing by way of illustration a preferred embodiment of the invention.

tn the accompanying drawings wherein like reference characters designate like parts throughout the several views:

Fig. 1 is a front elevaiticn of apparatus tor the treatment of tal ipes embodying some of the features of the invention;

I Fig. '2 is'an upside doam plan view of the apparatu's shown "in 1 with portions shown broken away or otherwlse'removed and shows a presoription angle ior the type of 'deform'ity wherein the heel-th me or center lines of the deformed feet-converge, and, in loroken lines, shows relative displacement of one of the shoes about an axis at the other shoe:

Fig. 3 is a View similar to Fig. 2, but shows the connections adjusted for a prescription angle for the type of deformity wherein the heel-:to-toe sites or center lines of the deformed feetare diver-sent;

:F'ig 4 is a view similar to Fig. 2 with portions removed and shows the shoes at the other iii-nits of their independent pivotal" movement;

Fig. 5 is a side viewof the novel apparatus and shows the connecting mans removably attached loth'e shoe; and

* Fig. 6 is a ha'gmentary cioss-seetion taken substantially along the lines i-li of Fig. :5.

The defomiity known as oliibfoot manifests itself sometimes as talipes eqninns or oalcaneous wherein the lower surfaces of the heel and ball of an afiiicted tool: are not lib-1513,1161; :but instead, when the ball of the afflicted toot engages a plane surface, the'heel is spaced from that surface, or in other words, a portion :of the foot apparently is displaced about a" line extending transversely of the foot. At other times the deformity is of the type, talipes varus or valgus wherein an afflicted foot is turned inwardly or outwardly with its inner or *outer'longitudinal side raised with reference to a horizontal surfaize engaged by the other longitudinal side or margin of the foot; or in other words, wherein the emitted foot apparently is turned about a substantially horizontal forwardly extending line at the lower end of the leg Not infrequently the deformity appears as talipes equino- -varus wherein the abnormality is a combination of those already described. All too frequently the-deformity includes still other abnormalities alone or oomlzimed with one or more of the foregoing such as that wherein the forwardly extending longitudinal center line of each or either root is tamed outwardly or diverges abnormally from that of the other foot or "wherein the outwardly. extending longitudinal center line of each oreither :foot is turned inwaroly or converges abnormally toward that of the other "foot. Y V

V-{Ireatment ofthe llleiortnity has hitherto frequently extended over a period. of years and involved surgery and, whether or not surgery was practiced, castsor splints of plaster of Paris for holding each deformed foot in an improved position. Such treatments usually follow a preliminary treatment requiring several weeks.

That preliminary treatment. is employed while the bones of the afflicted infant are still relative- 1y pliable and consists generally in repeated manipulation and massage whereby to coax or urge each deformed foot toward normal position. The bones, tendons and muscles of an infants feet being more or less pliable and undeveloped are generally responsive to such treatment, but have not sufficient strength to maintain the afflicted foot in an improved or thenormal position against the forces exerted by the abnormal tendons, tissues, and muscles in a direction urging the foot from its improved or normal position toward its deformed position,

The successive casts or splints, with or without the effects of surgery, are intended to counteract the effects of such forces tending to return the deformed foot toward its abnormal position.

Those casts or splints, besides being inconvenient to apply, expensive, and unsightly, impair mobility, blood circulation, and muscular development. Hence, such treatment, while more or less emcacious in straightening the deformed foot, frequently results in shrivelled, shrunken, or shortened legs and feet, which are almost as unsightly and otherwise undesirable as the deformity itself. Thus, however successful the conventional treatment may be in relieving the specific deformity, it frequently produces other physical impediments which are almost as great handicaps as the deformity itself would have been without correction.

According to the present invention, novel apparatus, applicable to the feet of the afflicted infant following the preliminary treatment, is provided for maintaining each deformed foot in the improved position resulting from such preliminary treatment, preventing it from returning to or toward its deformed position from that improved position, and yet enabling a user to move either or both of his feet in the opposite direction between the improved position and a position at substantially the normal limit of movement (Fig. 4), and to move his feet to and fro (Fig. 2) simulating walking. Thus the afflicted foot and the leg may be developed by exercise and the patient need not be immobilized during treatment. 7

Such novel apparatus is preferably adjustable to permit, where desired, periodic changes in the angle made by the forwardly extending longitudinal axes of the feet as the improvement progresses, whether that angle is greater or less than the normal or ultimately desired angle between such axes, and to adapt the apparatus for use in treating talipes or clubfoot wherein the forward end of either or each afi'licted foot diverges or converges toward that of the other foot. When made as prescribed by the physician and, if adjustable, adjusted by him or according to his prescription, the novel apparatus is easily applicable to and removable from the feet of the afilicted individual following the usual preliminary treatment as described hereinabove.

Illustrative of the invention, a presently preferred embodiment thereof is shown in the accompanying drawings. As therein illustrated, the novel apparatus comprises a pair of shoes II and I2 of usual construction. each with .a sole 4 I3 and a lace I4 or other suitable means for holding the shoe n the foot of an individual.

Such shoes when arranged on the feet and laced,

draw the inner sole surfaces snugly against the soles of the encased feet. Those shoes are pivotally connected together by novel means which deformed position, while permitting pivotal ends.

movement from and toward the improved position in a direction therefrom opposite that of the deformed position.

In the illustrated embodiment of the invention, the novel connecting means includes sole-rigidifying means I5 and I6 respectively attachable to the soles I3 of the shoes II' and I2. Those solerigidifying means I5 and I 6 are applicable to the shoes for the right and left feet, respectively. Otherwise they are identical. Each comprises a pair of metal plates I1 and I8 stamped or otherwise formed in size and shape to correspond to the size and shape of the sole of the shoe to which it is attachable. Those two plates I1 and I8 of each pair are spaced apart in superposed relationship by a forward block or spacer I9 and a rearward block or spacer 2|.

The spacer blocks I9 and 2 I' of each sole-rigidifying, means are formed of any suitable material in any desired shape. Preferably they are of leather, rubber, rubber composition, or other material which is non-absorbent and resists shrinkage. Each spacer block I9 preferably conforms to the configuration of the forward or toe end of a pair of .the' superposed plates I1 and I8 and is interposed therebetween at their forward Each spacer block 2I' is interposed between a pair of the plates I1 and I8 at the outer superposed margins thereof near the forward ends of their heel portions.

Each pair of superposed plates I1 and 13 with the interposed spacer blocks I9 and 2I is held in assembled relationship by screws, bolts, or other suitable securing means 22 extending through the plate I8 and anchored in or to the plate I"I, some of them passing through each of the spacer blocks I9 and 2|. When so assembled, the novel sole-rigidifying means serve to resist flexing of the shoe soles, when attached thereto, under such forces as those tending to return a deformed foot to a position wherein the lower surfaces of the heel and ball are not co-planar as in talipes equinus, and a position wherein either of the longitudinal margins of the lower surface is raised relative to the other of such margins, as in talipes varus. In addition, such sole-rigidifying means serve to carry the mounting means for novel link means 20 and cooperate therewith so to connect the shoes II and I2 that each is pivotally movable relative to the other about a pivot attached to its sole, and likewise about a pivot at the sole of the other shoe.

Various link means may be employed to provide such pivotal movement. In the illustrated embodiment of the invention, such link means comprises a radius bar or link 23 and a correction limit bar or link 24'each stamped or otherwise formed from a suitable metal of a thickness to be slidably receivable between the plates I1 and I 8 of the sole-rigidifying means I5 and I5.

The radius bar 23 is pivotally securedat one end between the plates I1 and I8 of the solerigidifying means I5 by suitable pivoting means asse ses such, for example, as a shouldered .zbolt 25 passing through the radius bar and threadedly anachored in a threaded aperture (not shown) in the plate .11, as showninFigA andFig. '5, or through the plate l8 and the radius bar and threadedly anchored in the plate SI 1 as shown in Fig. 2. The radius bar .23 extends from that pivotal connection the sole-rigidify'ing means it laterally to an identical connection at its opposite end on a shouldered bolt 26 anchored in the plate 1"! of the sole-rigidifying means' l 6. 1

Where desired, a plurality of selectable anchoring positions is provided for the opposite ends of the radius bar 23 :by the provision of a series of spaced threaded apertures 21 in the plate l"! of each of the sole rigidifying means I5 and 15, extending from adjacent the spacer block- 2] transversely inwardly of the heel portion, and respectively registering apertures 28 in the plate I8 of suflicient diameter as shown in Fig. 2 and Fig. 5 to permit the passage therethrough of the heads of the

bolts

25 and 25, or, as shown in Fig. 2, of fastening means of lesser diameter than the heads of those bolts. Thus the

pivotbolts

25 and 26 areeasily removable and replaceable and the distance between the heels'm'ay be fixed and adjusted by the physician or at hisdirectlon.

The correction limit bar 24 has formed, in its opposite ends, longitudinally extending elongated apertures 29. At one end that correction limit bar extends between the plates I1 and I8 ofthe sole-rigidi-fying means I5, and suitable means such for example, as a shouldered bolt '3I either passes through the aperture 29 in the correction limit bar and is thrcadedly anchored (not shown) in the plate 11 as shown in Fig. 5 or, as shown in Fig. 2, passes through the plate I8 and the aperture 29 and is threadedly anchored in the'plate ll. Like the radius bar 23, the correction limit bar 24 extends from such connection with the sole-rigidifying means I5 laterally to a position between the plates I1 and I8 of the sole-rigidifying means I6 where an-identi-cal connection is made at its opposite end on a shouldered bolt 32 assing through the elongated aperture 29.

Where desired, a plurality of selectable positions is provided for each of the shouldered

bolts

31 and 32 by the .provisi'on'of a series of spaced threaded apertures 33 in the plate [1 of the respective sole-rigidifying-means I5 and I5, extend- .ing from adjacent the inner margins thereof transversely outwardly along lines forwardly of the apertures 21, and respectively registering apertures 34 in the plate 18 of sufficient diameter, as shown in Fig. 5, to permit the passage therethrough of the heads of the bolts 3i and 32, or, as shown in Fig. '2, of fastening means of lesser diameter than the heads of those bolts. Thus the bolts '3I and 32 are easily removable and replaceable and cooperate with the elongated apertures 29 to limit the pivotal movement of the solerigidifying means about the bolts 25 and '26, respectively associated therewith, and the limits of the pivotal movement are adjustable as directed and prescribed by the physician.

The novel link means just described is adapted not only to permit and control desirable movements of the feet, but also to cooperate with the sole-rigidifying means for preventing the turneach sole of the shoes toiwhich they are attached in eo-planar relationship.

f accordance with the preferred embodiment of the invention, the assembled 'sole-rigidiiying and means constituting the novel connecting means already described are so attached to the shoes 1 I and 12 as to be more or less readily removable and attachable :to other shoes of the some our 2. dilferemt patient. The soles of the shoes 4 f aud '12 are arranged on the rfaces of the plates 13 opposite the plates l8 of the stile-fielditying i5 and 16, respectively. with the shoes and connecting means so arranged, wood screws 35 are inserted through apertures shown) in'the plates l1 and'threaded into the respectively adjacent soles of the shoes H and I2. ireierably the screw holes in the plates 1'1 for those screws 35Iare countersunk to receive the screw heads in :flush relationship with the outer or lower faces of the plates ll; If desired, apertures 36 are provided in the plates 1 8, registering with the screws 35 and of sufiicient diameter to permit the insertion and removal of the attaching screws 35 after the plates l8 are secured to the correspomlmg plates I '1. Q 7

As in Figs. 5 and 6, the toe or forward end of each sole-rigidifying means :is, where desired, provided with a suitable toe strap or cap 3] of, .for example, metal secured in any usual manner preferably to the plate I8 and forming above the plate :Il a toe-receiving recess or cavity into which the toe of the appropriate shoe is inserted. Such a toe cap cooperates with suitable means at the rear or heel portion of each sole-rigidify ing means to obviate the use of the 'woodscrews 35 for removably securing the connecting means to the shoes 1! and 12.

The presentlypreferred heel securing means as illustrated in Figs. 5 and 6 comprises for each sole-rigidifying means 1 5 and It, a pair of clamp members 38 threaded at their lower ends on threaded end portions 39 of a pin or shaft 41 rotatably carried intermediate the threaded portions 39 in bearing lugs 42 struck up from the plate :18 at its rear or heel end. The clamp members 38 of each pair extend upwardly above the pin 44 to adjacent the lower face of the plate I1 and outwardly beyond the opposite side edges thereof, thence upwardly. a distance above the plate 1 1 slightly greater than the thickness of the heel of the shoe. At their upper ends, the clamp members of each pair are turned inwardly for engagement on the heel of the shoe. One end of each pin 4| is preferably flattened or formed of polygonal shape as at 43 to facilitate adjustment of the associated pair of clamp members 38 to and from clamping engagement with shoe heels of different widths.

After the toe of each shoe is inserted in the toe cap 31, the corresponding pin 4! is operated to move the associated clamp members 38 into or from clamping engagement with the heel of the shoe tor attaching the connecting means to or removing it from a pair of shoes.

The sole-rigidifyl'ng means 45 and I6 cooperate with the link means 29 adjust-ably connected :as already described to each of them and extending therebetween to determine an adjustable prescription angle indicated .atRx in Fig. 2. The prescription angle R1: is the angle made by and included between the longitudinal axes or center lines or the sole-rigidifying means arranged at the respective limits of their lengths of movement toward the deformed position of the patients 1 feet for which the novel apparatus is prescribed.

Fig. 2 shows an Ra: angle for a deformity of the type wherein the forward or toe ends of the feet are convergent. By the preliminary treatment, the feet are manipulated to the improved position indicated in that view of the drawing and the novel apparatus is arranged on the feet. When the apparatus is so applied to the feet, the engagement of the bolts 3i and 32 with the inner ends of the respective apertures 29 prevents the simultaneous movement of both feet, from the position illustrated in Fig. 2 inwardly toward the deformed position, about the pivot bolts '25. and 26, and each foot resists the movement of the other foot from that improved position toward the deformed position.

If a different prescription angle is desired or if it is desired to change the prescription angle due, for example, to improvement of the afflicted individual, then either the bolts 3! and 32 are removed and inserted through the elongated apertures 29 into the appropriate anchoring apertures 33 in the plates ll or the

bolts

25 and 26 are removed and are inserted into the appropriate anchoring apertures 21 of the respective plates I! or both of the described adjustments may be employed to obtain a desired prescription angle and to vary it as may be necessary or desirable. For example, Fig. 3 shows the bolt 3i anchored in the outer aperture 33 of the plate l7. By moving both the bolts 3| and 32 to the outer anchoring aperture 33 of the respective plates i'i substantially the same prescription angle as that shown in Fig. 2 is obtained, but the angle of Fig. 3 is for the deformity of the type wherein the forward or toe ends of the feet are divergent. Thus the bolts 3| and 32 engage the outer ends of the respective elongated apertures 29, preventing simultaneous movement of the feet from the position of Fig. 3 outwardly toward the deformed position. With that arrangement as described in connection with Fig. 2, each foot resists the movement of the other foot from the improved position toward the deformed. position.

While as already described, the novel apparatus prevents movement of the deformed feet from the prescribed or attained improved position toward the deformed position, it will be observed by reference to Figs. 2, 3, and 4 that the patient or user may nevertheless move his feet independently of or simultaneously with each other, from the selected improved position outwardly from the position of Fig. 2 to the position shown in Fig. 4 or, as the case may be, inwardly from the position of Fig. 3 to a position (not shown) which like the Fig. 4 position is at substantially the normal limit of movement of the feet in a direction from the improved position opposite that of the deformed position, and return the feet to the prescribed improved position. In so moving, the sole-rigidifying means [5 and It rotate about the axes of the

respective bolts

25 and 26. The elongated apertures 23 cooperate with the bolts 3| and 32 to permit and control such movement between the limits just described.

By reference to Fig. 2 it will also appear that either of the sole-rigidifying means l5 and I6 and, hence the respective feet to which they are attached, is swingable forwardly and rearwardly of the other about the axes of the bolts 25 and 3! on the one hand and on the other hand about the axes of bolts 26 and 32.- While in Fig. 2 by the broken lines only the solerigidifying means at the left is shown as having been swung rearwardly about the axes of the bolts 25 and 3!, it will be obvious that the broken lines may represent an original position and the'full line position of the sole-rigidifying means at the right in that view of the drawing would then illustrate a forward swinging at that solerigidilying means. Since the connections at the opposite ends of the link means 20 to the solerigidifying means l5 and [6 are identical, then obviously the sole-rigidifying means at the left in Fig. 2, like that at the right, is adapted for forward swinging movement, that at the right like the one at the left is adapted for rearward swinging movement, as just described. The spacer blocks l9 and 2| serve to limit such movement of the feet. Thus a wearer is enabled to simulate walking. It should be observed that during such movements simulating walking the prescription angle is maintained. The exercise attainable with the novel apparatus as thus far described promotes development of afflicted feet while they are being held out of their deformed positions.

Being anchored at their opposite ends to the sole-rigidifying means, the connecting links 23 and 24 resist any tendency of either foot of a wearer to turn in such manner as to move either longitudinal margin upwardly or downwardly relative to the other longitudinal margin of the same foot. Since the elevation or depression of either end of a foot relative to the other end of the foot results in a twisting force or torque being applied to the connecting links, they resist such movements. Thus the novel apparatus may be employed to prevent the feet of an individual afllicted with talipes varus, valgus, equinus, calcaneus, and equino-varus from returning from an attained improved position to the deformed position.

We claim:

1. In apparatus of the class described, the combination with a pair of shoes, of means for maintaining the ball and heel portions of one shoe of said pair in substantially coplanar relation ship, and means for restricting movement of said one shoe about an axis substantially perpendicular to the sole of that shoe to a range having as one limit the normal limit of foot movement in one direction and as its other limit of movement in the other direction a predetermined position between the normal limits of foot movement about said axis, said shoes being connected by means enabling swingable movement of said one shoe about an axis spaced from the first mentioned axis.

2. In apparatus of the class described, the combination with a pair of shoes, of means for preventing one shoe of said pair from turning about a line substantially parallel to the longitudinal axis of the shoe sole, and means for restricting movement of the said one shoe about an axis substantially perpendicular to the sole of that shoe to a range having as one limit the normal limit of foot movement in one direction and as its other limit of movement in the other direction a predetermined position between the normal limits of foot movement'about said axis, said shoes being connected by means enabling swingable movement of said one shoe about an axis spaced from the first mentioned axis.

3. In apparatus of the class described, the combination with a pair of shoes, of means for maintaining the ball and heel portions of a foot in a shoe of said pair in substantially -co-planar relationship and the lon itudinal margins of the lower surface of said foot in substantially normal, relative positions, and connecting means for said shoes effective to limit movement of the foot in one of said shoes about an axis substantially perpendicular to and intersecting the sole of that shoe to a range having'as one limit the normal limit of movement in one direction and as its other limit of movement in the other direction a predetermined position between the normal limits of movement of the foot about said axis, said connecting means being efiective to limit swingable movement of said one shoe about a pivot perpendicular to and. intersecting the sole of the other shoe to a predetermined range.

4. In apparatus of the class described, the combination with a pair of shoes, of means for preventing relative displacement of the forward and rear sole portions of a shoe of said pair, means for preventing relative displacement of the longitudinal sole margins of said ShOe with respect to a surface parallel to the shoe sole, and means for fixing said shoe against pivotal movement about an axis vertical to the sole of that shoe at one side of a predetermined position, the

,of a user, of means for resisting displacement of either end of each shoe relative to the other shoe about a transverse axis and of either longitudinal margin of each shoe relative to the other shoe about a longitudinal axis, means extending between said shoes for holding the shoes in spaced relationship, means connecting each said shoe to the last said means in any of a plurality of positions for pivotal movements about a vertical axis, and means for adjustably restricting the pivotal movement of each shoe about the vertical axis thereof to a range having as one limit substantially the normal limit of foot movement about a vertical axis in one direction and as its other limit an adjustable position intermediate the first said limit and the other normal limit of foot movement about a vertical axis in the other direction.

6. In apparatus of the class described, a pair of shoes, sole-rigidifying means secured to the sole of each of said shoes, link means pivotally connected respectively at opposite ends to said sole-rigidifying means and cooperating therewith to hold said shoes in spaced relationship and adapting each shoe for independent and correlated movements about: the vertical axis as-' tical axis associated with the other shoe, means for limiting the pivotal movements of each shoe in opposite directions, and means for adjusting the limits of pivotal movement of each shoe.

8. In apparatus of the class described, a pair of shoes, means for spacing said shoes apart, pivot means connecting each said shoe to the last said means and providing separate pivotal axes vertical to the soles of the respective shoes,

the spacing means and said pivot means adapting a said shoe for pivotal movements about both said axes, and means for limiting the extent of pivotal movement of said shoe about each of said axes.

9; In apparatus of the class described, a pair of shoes, means subjacent the soles of said shoes for spacing said shoes apart, and pivot-means under the soles of the respective shoes connecting them to thelast said means and adapting each said shoe for limited pivotal movement about both said pivot means.

10. In apparatus of the class described, a pair of shoes, metal plates each of sole shape for the respective shoes and attached thereto, pivot members anchored in the respective plates at the heel portions thereof, and link means having opposite ends pivoted to said plates by said pivot members and having a slidable connection with each said plate forwardly of the pivot member anchored therein, each said slidable connection being adapted to limit pivotal movement of the associated shoe and metal plate about the pivot member anchored therein.

11. In apparatus of the class described, the combination with a pair of shoes, of connecting means including means for spacing said shoes I apart and adapting them for limited pivotal ambulatory movements about a pair of spaced parallel axes, and means for removably securing said shoes on said connecting means over the respective axes with the shoe soles at right angles thereto. I

12. A method of treating clubfoot, which comprises arranging shoes on the feet of the afilicted individual, fixing one of said shoes for coincidental limited pivotal movements about two spaced axes intersecting respectively the soles of both,

7 shoes, and limiting said pivotal movement about the axis intersecting said one shoe to a predetermined position between the deformed position of the foot and its normal limit of turning movement about the last-mentioned axis.

13. In apparatus of the class described, the combination with a pair of shoes of means for connecting said shoes, said connecting means comprising spaced pivotal connections, one associated with each shoe, means for enabling free turning movement of each of said shoes about its respective pivotal connection, and means for limiting such free turning movement about each connection whereby limited ambulatory movement of the shoes is permitted.

PHILIP R. BRACHMAN. 1 ORVILLE C. SONNTAG.

REFERENCES CITED 7 The following references are of record in the file of this patent:

UNITED STATES PATENTS Germany I Aug. 8, 1919