US2121773A - Motion checking apparatus - Google Patents

Description

June 28, 1938. w. B. EDDISON MOTION CHECKING APPARATUS Filed Jan: 30, 1936 3 Sheets-Sheet l v Qw kw b@ I a k nu w 7 @Q June 28, 1938. w. B. EDDISON 2,121,773

MOTION CHECKING APPARATUS Filed Jan. 30, 1936 3 Sheets-Sheet 2 /m/e/1 for June 28, 1938. w B, EDDI N 2,121,773

MOTION CHECKING APPARATUS Filed Jan. 30, 1936 3 Sheets-Sheet 3 Patented June 28, 1938 PATENT OFFICE MOTION cnncxnm APPARATUS William Barton Eddison, Ardslcy on Hudson, N. Y.

Application January'iii), 1936, Serial No. 61,550

jzaclaims.

This invention relates to an improvement in motion-checking apparatus and is particularly suitable for checking the oscillatory movement of time-instrument balance-wheels, though-available for other uses.

One of the objects of the present invention is to provide a superior motion-checking apparatus characterized by convenience and simplicity of use.

A further object is to provide a superior 'apparatus of the class referred to which is characterized by accuracy of performance.

Another object of the present invention is to provide an apparatus of the class referred to by means of which eye-strain is minimized.

A still further object is .to provide a superior motion-checking. apparatus which will clearly and accurately indicate whether the motion being checked is either slow or fast with respect to a predetermined standard rate. v

With the above-andother objects in view, as will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings and appended claims, the

present invention includes all features disclosed therein which are novel over the prior art.

, In the accompanying drawings:

Fig. 1 is a schematic perspective view illustrating one form which an apparatus embodying the present invention may assume, the parts being shown in position preparatory'to the start of a cycle of operation;

Fig. 2 is a broken view in elevation of the two pendulums, the latching mechanism and associated parts, the pendulums being shown in their retired and latched positions;

Fig. 3 is a corresponding view but showing the shutter-pendulum as released and traveling on its advance swing and the beam-control pendulum at the instant of its release for advance swinging movement;

Fig. 4 is a view showing the beam-control pendulum in position to project. a beam of light through the balance-wheel being checked and the shutter-pendulum advanced in its forward swinging movement to a point sufficient to permit the projection of the beam;

Fig. 5 is a view corresponding to Fig. 4 but showing the beam-control pendulum at the limit of its outward swinging movement and the shutter-pendulum in motion on its back swing;

Fig. 6 is a view corresponding to Figs. 4 and 5 but showingthe beam-control pendulum midway of its return stroke and in position to project a beam through the balance-wheel being tested, which beam-projection is prevented by. the shutter-pendul'um, which is also swinging on its return stroke;

Fig. 7 is a broken detail perspectiveview showing the tensioning-finger engaged with the balance-wheel; and

Fig. 8 is a diagrammatic view showing the path followed by the light beam when the beam-control pendulum and the shutter-pendulum are in proper relationship with respect to each other and with respect to the other related features of the apparatus.

The embodiment of the invention herein chosen for illustration includes a beam-control pendulum generally designated by the numeral 28 and a shutter-pendulum generally designated by the numeral 2|, both of which are adapted to swing in such manner as to have effect upon light emanating from a suitable light-source such, for

instance, as the filament 22 of an incandescent electric lamp 23. When the pendulums 28 and 2| are in a proper position and relationship as will hereinafter appear, the image of the said filament 22 is received horizontally by a fixed prism 24 and deflected upwardly thereby to a beam-control prism 25 carried by the beam-control pendulum 20. The beam received by the prism 25 just referred to, is deflected by the said prism 25 through a lens system generally designated by the numeral 26 which is interposed between the prism 25 and a fixed prism 21 which is tilted as shown in Figs. 1 and 8 to deflect the beam laterally and slightly upwardly for passage through the lower portion of a balance-wheel 28 having, as shown, two diametrically- opposite spokes 29 and 29.

Light deflectors in the form of prisms are preferred where shown, but it is obvious that other forms of light deflectors such, for instance, as mirrors, may be substituted therefor.

The balance-wheel 28 is rigidly mounted in the usual manner upon a balance-staff 38 which is supported at one end with capacity for free oscillation in a bracket 3| and at its opposite end in a tapered supporting-rod 32 extending substantially-axially with respect to the balancestaff .30. Secured to the balance-shaft in any approved manner is one end of a spiral so-called hairspring" 33 which has its opposite end gripped between two coacting adjusting rollers 34-,-34, as shown in Fig. l of the drawings.

After passing through the lower portion of the balance-wheel 28, the beam of light deflected by the prism 21 passes through an aperture 35 in the bracket3l and thence to a lens 36 by means ofwhich it is focused through an aperture 31in a screen-supporting bracket 38 upon an inclined mirror" 39. The mirror 39 or other suitable light deflector serves to deflect the beam I of light received from the lens 36 forwardly and upwardly through a translucent observation segment 48 provided in an upwardly-extending rearwardly-inclined screen 4]. The said screen ll is preferably provided with a suitable shield such as 42 to guard against undesirable extraneous light rays,'and is preferably formed of a plate of ground glass having all save its segment 40 rendered substantially opaque by suitable backing material. Arranged along the upper edge of the segment 40 of the screen 4l are a series of graduations 43 serving to assist an observer in determining whether the rate of oscillation of the balance-wheel 28 is correct orslower or faster than that desired.

Returning now to the pendulums 28 and 2|,

44 mounts a holder 49 which carries the beam-- control prism 25 before referred to and which is provided in its outer face with a hardened steel insert 50 constituting a latching-abutment for engagement by the hooked outer end of a latch 5|. The said latch 55 is rigidly mounted upon a rock-shaft 52 supported at its respective opposite ends in brackets 53 and 54.

The shutter-pendulum 2|, while intended to operate out of phase with the beam-control pendulum 28, is designed to have the same period of oscillation as the said pendulum 20. The said shutter-pendulum 2| includes a rod 55 secured at its upper end to a knife-edge pivot-bar 55 rocking at one end on the supporting-member 4'! before referred to and at its opposite end on a supporting-member 5i. Like the rod 44, the rod 55 has its lower portion externally-threaded to receive an internally-threaded adjusting-weight 58.

The lower end of the rod 55 of the pendulum 2i carriesa disc-shaped weight 59 from which ofisets a shutter-plate 58 which is adapted on occasion to be interposed in the light path between the filament 22 of the lamp 23 and the fixed prism '24. The weight 59 of the pendulum 2! is also provided with an offsetting latch-arm 6B which is engaged by the hooked end of a latch 82 pivotally mounted upon a stud 63 carried by a bracket 64.

The latch 82, which serves 'to hold the shutters pendulum 2| in its retired position, is provided with a laterally-ofi'setting L-shaped trippingfinger which is adapted on occasion to be engaged by a tripping arm 68 secured to a stud 67 which in turn rigidly offsets from an L-shaped side-bar 68 and which is rotatably mounted in the supporting-member 5'? upon which the pivot-bar 56 of the shutter-pendulum 2| bears, as before described. Arranged in spaced relationship with respect to the side-bar 68 is a companion side-bar 89 which carries a stud l0 hearing in the supporting-member 46 in axial alignment with the stud 81 before referred to.

Rigidly mounted in the ends of the side-bars 88 and 659 remote from the studs 81 and i8 is a cross-bar H to which is rigidly clamped a resilient resetting-arm 12 which is adapted to engage with the weight 59 of the shutter-pendulum 2| to swing the latter into its retired position. Also rigidly clamped to and ofi'setting from the cross-bar H are a pair of corresponding resetting-arms 13-13 respectively adapted to engage with projections such as 14 oifsetting in opposite directions from-thesides of the prismholder 49 of the beam-control pendulum 20, and serving to swing the latter into its retired position.

The side-bar 88 before referred to which together with the complementary side-bar 69 and cross-bar II forms a yoke-shaped unit, is provided with a depending operating-arm 15 to the lower end of which is pivoted the head 18 of an operating-link I1, the opposite end of which latter is provided with a threaded-on head 18 which is pivotally attached to a connecting-lever 19 adjacent the upper end thereof. Intermediate its respective opposite ends, the connecting-lea ver 19 is mounted for rocking movement upon a stud 88 which in turn is mounted in a bracket provided with a ball-like terminal 83 fittingwithin a slot 84 in the inner end of a manual operating-lever 85 having a broad terminal 'fing'er-piece 88 and pivotally mounted intermediate its ends upon a stud 81 vertically mounted in the bed-plate 82 before referred to. The said manual operating-lever. 85 is restrained against too free swinging movement by a hellcal tensioning-spring 88 mounted upon the stud 81 which is adjustably threaded in' the bed-plate 82. The horizontal swinging movement of the operating-lever 85 is limited by means of a pair of spaced-apart and adjustable stops 8989 mounted upon the upper surface of the bedplate 82.

As will appear more fully hereinafter, the shutter-pendulum 2! is first released and when it reaches a predetermined position in its advance swing relative to the beam-control pendulum 2B it serves to eifect the release of the latter pendulum. I

For the purpose just above referred to, the latclrarm 8! of the shutter-pendulum 2! is adapted when released to engage a tripping-loop 98 which is pivoted at one of its ends in the bracket 84 before referred to and at its opposite end coaxially pivoted in a bracket 9!. The said loop whenthe pendulums are in their latched positions' as shown in Fig. 1 rests against a stop 92 carried by the bracket 9! and is held in such position, which is just slightly past dead-center, by a helical actuating-spring 93.

The tripping-loop 96 above referred to is adapted to be rapidly snapped to the right and downwardly (as viewed in the drawings) for cam-like engagement with the rear edge of the lower and of a double -ended tripping-lever 94 which latter is rigidly mounted upon the rock-shaft 52 to which the latch 5| before-referred to is also seemed. The forward and downward swinging movement referred to of the tripping-loop 9!! is checked by a stop-finger 95 mounted in the bracket 9|. The said shaft 52 is encircled by a helical spring 98 which exerts a constant effort to turn the said shaft in a direction required to swing its latch 5| downwardly for engagement with the referred to. The said resetting-lever 01 carries a resetting-arm 33 which is engageable with the tripping-loop 30 for resetting the same as described.

The resetting-lever 91 is swung upwardly and rearwardly for the purpose of resetting the tripping-loop 30 by means of a resilient-arm I secured to the depending operating-arm II to which the operating-link I1 is pivotally connected.

The upper end of the connecting-lever I3 is bifurcated to form a coupling-notch IOI receiving a coupling-pin I02 laterally offsetting from a tensioning-slide I03 which is mounted for reciprocating movement toward and away from the balance-wheel 28 in a guide-head I04 carried at the upper end of the bracket BI before referred to. At its forward end the tensioning-slide I03 carries a resilient tensioning-flnger I05 which may be made of spring steel and which is preferably adapted to engage the periphery of the balance-wheel 28 to rotate the same for the purpose of tensioning the hairspring 33 preparatory to the release of the said balance-wheel 02.05- cillation by the said hairspring during the testing or checking period. The said tensioning-flnger in its engagement with the balance-wheel 23 will move from the position in which it is indicated by full lines in Fig. 1 to the position in which it is indicated in broken lines in the same figure.

For the purpose of rapidly disengaging the tensioning-finger I05 from the balance-wheel 23 to release the balance-unit of which the same forms a part, for free oscillation after the hairspring 33 has been tensioned as above described, a releasing-finger I06 is provided. The said releasing-finger is mounted in the outer end of an arm I01 rigidlysecured to one end of a rockshaft I08 which bears in the guide-head I04 at a point above the resilient tensioning-flnger I05. The opposite end of the rock-shaft I03 has rigidly secured to it a downwardly-extending arm I03 to the lower end of which is connected the forward end of a releasing-link IIO which preferably is in the form of a relatively-light though sumciently-rigid strand of piano wire or other suitable material. The said releasing-link is guided in its reciprocating movement in a guide-tube II I suitably supported in the framework of the apparatus. The end of the releasing-link IIO opposite to the end which is pivotally connected to the arm I03 is connected to the upper end of the tripping-lever 34 before referred to so as to move concurrently therewith when the same is struck by the tripping-loop 30 in a manner as will be hereinafter described.

For the purpose of a better understanding of the mode of operation of the particular motionchecking apparatus herein chosen for the illustration of the present invention, let it be assumed that the parts are in the positions in which they are shown in Figs. 1 and 2, in which it will be noted that both the beam-control pendulum 20 and the shutter-pendulum 2| are in their latched positions and the balance-wheel is oriented so that one of its spokes extends vertically downward. Let it be presumed further that the filament 22 of the incandescent electric lamp 23 is energized so as to supply the necessary lightbeam. Let it also be assumed that the said incandescent lamp 23 is provided with a suitable shield such'as H2 (Fig. 8) which will permit the light-beam to pass freely toward the fixed prism 24, but guard against the impingement of. stray light rays upon the various other light deflectors and lenses.

If, now, the finger-piece 36 of the manual operating-lever 83 is moved from left to right, this movement will correspondingly move the upper end of the connecting-lever I3 and will simultaneously move the tensioning-siide I03 and the operating-link 11 from left to right. I

The movement of the tensioning-slide, just referred to, will serve to move the resilient tensioning-finger I05 carried thereby into engagement with the forward portion of the periphery of the balance-wheel 20, and will rotate the same to thus tension the hairspring 33. The said tensioning-finger I05, at the limit of its advance movement, will assume the position in which it is indicated by full lines in Fig. 7.

Simultaneously with the movement of the ten: sioning-slide I03 and its associated parts, the operating-link 71 will be moved with the effect of rocking in a counterclockwise direction, the yoke-shaped unit formed by the side-bars 68 and 83 and cross-bar II about the studs 01 and I0. This movement will similarly effect a corresponding swinging movement of the parts carried by or connected to the said yoke-shaped unit.

As the movement just above referred to takes place, the resilient-arm I00 carried by the operating-arm I5 will be moved out of engagement with the resetting-lever 91 and thus permit the same ,to swing forwardly and downwardly by gravity so as to clear its resetting-arm 00 from the path of the tripping-loop 30.

The swinging movement of the yoke-shaped unit will serve also to retire the resetting-arms I2 and 13-13 out of the path of movement of the respective pendulums 2I and 20.

The counterclockwise rocking movement of the yoke-shaped unit, above referred to, will further cause the descent of the tripping-arm 86 and'its ultimate engagement with the tripping-finger 65 carried by the latch 82, with the ultimate effect of disengaging the latch 62 from the latch-arm 6| of the shutter-pendulum 2| at a time that the resetting-arms l2 and 13-13, above referred to, have been sufiiciently retired. Thus, the shutterpendulum will be released for swinging movement from left to right.

When in its swinging movement from left to right, as described, the shutter-pendulum 2| reaches substantially the position in which it is shown in Fig. 3, its latch-arm 6| will have engaged with and have swung the tripping-loop 30 to the other side of its dead-center from that indicated in Figs. 1 and 2. As soon as the tripping- -loop has been swung in advance of deadcenter, as just described, the spring 33 will act to snap said loop in a clockwise direction, thus causing the same to engage the adjacent edge of the tripping-lever 34, with the effect of turning the same in a counterclockwise direction. Inasmuch as the said tripping-lever 94 is rigidly attached to the rock-shaft 52 carrying the latch H which serves the beam-control pendulum 20, the said'shaft 52 will be similarly rocked in its bearings, with the effect of disengaging the nose of the latch 5| from the latch-abutment 50 of the beam-control pendulum 20. The parts will now have assumed substantially the positions in which they are shown in Fig. 3.

Simultaneously with the rocking of the tripping-lever in a counterclockwise direction, the wire-like releasing-link IIO, owing to its connection with the tripping-lever 94, will be moved from right to left with the effect of swinging the releasing-finger Hi6 downwardly so as to flex the tensioning-finger I out of engagement with the periphery of the balance-wheel 28, as indicated in Fig. 7. The said balance-wheel and the balance-unit of which it forms a part will commence its oscillatory movement under the urge of its hairspring 33 simultaneously with the release of the beam-control pendulum 20.

From the foregoing, it will be seen that after the shutter-pendulum 2| has been manually released and has moved to a predetermined point in its advanced swing, the said shutter-pendulum will automatically efiect the release of the beamcontrol pendulum 20 and the balance-unit.

When the beam-control pendulum reaches substantialLy the position in which it is shown in Fig. 4, the beam-control prism 25 carried thereby will pick up the image of the filament 22 from the fixed prism 24 or other suitable light deflector. The said beam-control prism 25 will now deflect the image of the filament 22 through the lens system 26, thence to the inclined prism 21 and through the space within the lower portion of the rim of the now oscillating balance-wheel 28. The image of the filament will pass on through the lens 36, etc., for impingement upon the rear surface of the screen ti and through the translucent observation segment 20 in the latter. The shadow of the spoke 29 of the balance-wheel 28 may now be seen through the said observation segment ill each time the pendulum 20 advances but not when the same retires. The pendulums 2G and 2| will now have assumed substantially the positions in which they are shown in Fig. 4,

in which it will be noted that the shutter-plate M of the shutter-pendulum 2i has passed the fixed prism 26, so as not to interfere with the reception by the latter of the image of the filament 22 when the beam-control prism 25 is swinging from left to right.

In Fig. 5, the beam-control pendulum 20 is shown substantially at the limit of its advance movement, and it will be noted that the shutterpendulum has at this time moved part way back on its return swing.

Owing to the out-of-phase relationship between the beam-control pendulum 20 and the shutterpendulum 2!, by the time that the beam-control prism 25 of the pendulum 20 has swung back over the fixed prism 24, as indicated in Fig. 6, the shutter-pendulum 2! will have moved even further on its return swing so as to interpose its shutter-plate 653 between the filament 22 and the fixed prism 25, thus precluding the image of the said filament from reaching the observation segment 40 during the return swing of the beamcontrol pendulum 20. Both of the pendulums 2B and 2i will continue to swing back and forth in substantially the same out-of-phase relationship above described, with the effect of impinging the image of the filament 22 upon the rear face of the screen 4! for observation through the segment 40 thereof once during each swing of the beam-control pendulum from left to right, but not during the swing of the said pendulum from right to left The purpose of precluding the deflection of the image of the filament 22 to the screen 4| during one of the phases of each cycle of the beamcontrol pendulum 20 is to avoid confusion between the shadow of a given one of the spokes 29 and 29 of the balance-wheel 28, when such spoke is moving in opposite directions. The arrangement just referred to insures that the shadow of the lower spoke of the balance-wheel 28 will show through the observation segment 4!! only when the said spoke is swinging in a clock wise direction and not when it is swinging back in a counterclockwise direction.

If the shadow of the selected spoke of the balance-wheel 28 remains substantially stationary in the center of the observation segment 40 for a plurality of movements of the pendulum 20, assurance is had that the said balance-wheel is in time with the said pendulum 20, which latter, together with the shutter-pendulum 2|, is carefully timed to a predetermined rate. If the shadow of the selected spoke of the balance-wheel 2B appears to the left of the center of the observation segment 40, this will indicate that the rate of oscillation of the said balance-wheel is slow as compared to the predetermined standard. The speed of oscillation of the balance-wheeL may now be increased by suitably adjusting the hairspring 33, which may be effected conveniently by turning the adjusting-rollers 34-34 to in effect shorten the said hairspring 33 in such manner as not to disturb the previously-determined position of the selected spoke of the said balance-wheel when midway of its swing. If, now, the swinging movement of the pendulums 20 and 2! has not so far died down as to be ineffective, the shadow of the selected spoke may be again observed in the segment to or, if desired, the apparatus may be restarted.

If the shadow of the spoke should appear to the right of the center of the observation segment 60, this will be an indication of the fact that the balance-wheel is oscillating at a too-rapid rate as compared to the predetermined standard and may be compensated for by turning the adjustlug-rollers 34l--3i to lengthen the effective portion of the hairspring 33.

It is to be here noted that in referring as above to the fact that the appearance of the shadow of the selected spoke in the left side of the observation segment 40 indicates that the balancewheel is oscillating at a rate below standard, this condition would be reversed with a hairspring which is wound in the opposite direction. Thus, it might be that with some types of balancewheel units, the appearance of the shadow of the selected spoke in the left portion of the observation segment to would indicate a too-rapid rate of oscillation rather than a two-slow rate, as before described.

The pendulums 20 and 2| may be restored to their latched positions in which they are indicated in Figs. 1 and 2, preparatory to another testing operation either upon the same or a different balance-wheel, by swinging the finger-piece 86 of the manual operating-lever 85 from right to left, which will cause the various resetting-arms to restore the parts to the positions in which they are indicated in Figs. 1 and 2.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are therefore to be considered in all 'respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A motion-checking apparatus including in combination: a source of light; a movable beamcontrol member acting to flash a beam of light from the said source at predetermined intervals upon the object whose motion is to be checked; and a shutter-member movable into the path of the beam emanating from the said source and acting to periodically nullify the stated action oi. the said beam-control member. v

2. A motion-checking apparatus including in combination: a source of light; a movable beamcontrol member acting to flash a, beam of light from the said source at predetermined intervals upon the object whose motion is to be checked; and means for nullifying every alternate one of the stated actions of the said beam-control member.

3. A motion-checking apparatus including in combination: a source of light; a movable beamcontrol member acting to flash a beam of light from the said source at predetermined intervals upon the object whose motion is to be checked; and a shutter-member movable into the light path between the said source and the said beamcontrol member to periodically nullify the stated action of the latter.

4. A motion-checking apparatus including in combination: an observation-screen; a source of light; a movable beam-control member acting to flash a beam of light from the said source at predetermined intervals upon the observationscreen and upon the object whose motion is to be checked; and a shutter-member movable into'the path of the beam emanating from the said source and acting to-periodically nullify the stated action of the said beam-control member in flashing a beam of light upon the said observation-screen.

5. A motion-checking apparatus including in combination: an'observation-screen; a source of light; a movable beam-control member acting to flash a beam of light from the said source at predetermined intervals upon the said observation-screen and upon the object whose motion is to be checked; and means for nullifying every alternate one of the stated actions of the said beam-control member in flashing a beamoi light upon the said observation-screen.

6. A motion-checking apparatus including in combination: an observation-screen; a source of light; a movable beam-control member acting to flash a beam of light from the said source at predetermined intervals upon the said observation-screen and upon the object whose motion is to be checked; and a shutter-member movable into the lightpath between thesaid source and the said vbeam-control member to periodically nullify the stated action of the latter.

7. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and a shutter-member movable into the path of the beam of light emanating from the said source and acting to periodically nullify the stated action of the said beam-control pendulum.

8. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and means for nullifying every alternate one of the stated actions of the said beam-control pendulum.

9. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum having a light-deflector serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and a shutter-member movable into the light-path between the said source and the light-deflector oi the" said beam-control pendulum to periodically nullity the stated action of the said beam-control pendulum.

10. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum having a light-deflector serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and means for nullifying every alternate one of the stated actions of the said beamcontrol pendulum.

11. A motion-checking apparatus including in combination: an observation-screen; a source of light; a beam-control pendulum acting to flash a beam of light from the said source at predeter-v checked; and means for nullii'ying every alternate one of the stated actions of the said beamcontrol pendulum in flashing a beam of light upon the said observation-screen.

13. A motion-checking apparatus including in combination: an observation-screen; a source of light; a beam-control pendulum acting to flash a beam or light from the said source at predetermined intervals upon the said observation-screen and upon the object whose motion is to be checked; and a shutter-member movable into the light-path between the said source and the said beam-control pendulum to periodically nullii'y the stated action of the latter.

14, A motion-checking apparatus including in combination; an observation-screen; a source-of light; a beam-control pendulum acting to flash a beam of light from the said source at predetermined intervals upon the said observationscreen and upon the object whose motion is to be checked; and means for nullifying every alternate one of the stated actions of the said beamcontrol pendulum. I

15. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and a shuttenpendulum movable into the path of the beam of light emanating from the said source and acting to periodically nullify the stated action of the said beam-control pendulum.

16. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and pendulum-means for nullifying every alternate one of the stated actions of the said beam-control pendulum.

17. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum carrying a light-deflector serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and a shutter-pendulum movable into the path of the beam of light emanating from the said source and acting to periodically nullify the stated action of the light-deflector carried by the said beam-control pendulum.

18. A motion-checking apparatus including in combination: a source of light; a beam-control pendulum carrying alight-deflector serving to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and pendulum-means for nullifying every alternate one of the stated actions of the said beam-control pendulum.

19. A motion-checking apparatus including in combination: a source of light; an observationscreen; a beam-control pendulum acting to flash a beam of light from the said source at predetermined intervals upon the object whose motion is to be checked and upon the said observationscreen; latching-means releasably holding the said beam-control pendulum in a retired position; a shutter-pendulum movable into the path of the beam emanating from the said source and acting to periodically nullify the stated action of the said beam-control pendulum in flashing a beam of light upon the said observation-screen; latching means for releasably holding the said shutterpendulum in a retired position; and releasingmeans brought into action by the movement of one of the said pendulums to release the other thereof.

20. A motion-checking apparatus including in combination: a source of light; an observationscreen; a beam-control pendulum acting to flash a beam of light from the said source at predetermined intervals upon the object whose motion is to be checked and upon the said observationscreen; latching-means releasably holding the said beam-control pendulum in a retired position; a shutter-pendulum movable into the path of the beam emanating from the said source and acting to periodically nullify the stated action of the said beam-control pendulum in flashing a beam of light upon the said observation-screen; and releasing-means brought into action by the movement of the said shutter-pendulum to release the said beam-control pendulum.

21. A motion-checking apparatus including in combination: means for mounting a balancewheel unit whose motion is to be checked; a source' of light; movable light-flashing means acting to periodically flash a beam of light from the said source upon said balance-wheel unit; and mechanical means serving to start the said balance-wheel unit substantially simultaneously with the starting of the said light-flashing means.

22. A motion-checking apparatus including in combination: means for mounting a balancewheel unit whose motion is to be checked; 2. source of light; a light-flashing pendulum acting to periodically flash a beam of light from the said source upon said balance-wheel unit; and means serving to start the said balance-wheel unit substantially simultaneously with the starting of the said light-flashing pendulum.

23. A motion-checking apparatus including in combination: means for mounting an oscillatable balance-wheel unit having a hairspring; a source of light; movable light-flashing means acting to periodically flash a beam of light from the said source upon the said balance-wheel unit; tensioning-means engageable with the balancewheel unit and serving to tension the hairspring thereof; and means serving to disengage the said tensioning-means from the said balance-wheel unit substantially simultaneously with the starting of the said light-flashing means.

24. A motion-checking apparatus including in combination: means for mounting an oscillatable balance-wheel unit having a hairspring; a source of light; a light-flashing pendulum acting to periodically flash a beam of light from the said source upon the said balance-wheel unit; tensioning-means engageable with the balancewheel unit and serving to tension the hail-spring thereof; and means serving to disengage the said tensioning-means from the said balance-wheel unit substantially simultaneously with the starting of the said light-flashing pendulum.

25. A motion-checking apparatus including in combination: means for mounting an object whose motion is to be checked; a source of light; movable light-flashing means acting to periodically flash a beam of light from the said source upon the object whose motion is to be checked; a movable shutter acting to periodically nullify the stated action of the said light-flashing means; and means serving to start the said object substantially simultaneously with the starting of the said light-flashing means.

26'. A motion-checking apparatus including in.

combination: means for mounting an object whose motion is to be checked; 2. source of light; a light-flashing pendulum acting to periodically flash a beam of light from the said source upon the object whose motion is to be checked; a shutter-pendulum acting to periodically nullify the stated action of the said light-flashing pendulum; and means serving to start the said object substantially simultaneously with the starting of the said light-flashing pendulum.

27. A motion-checking apparatus including in combination: means for mounting an oscillatable balance-wheel unit having a hairspring; a source of light; movable light-flashing means acting to periodically flash a, beam of light from'the said source upon the said balance-wheel unit; a movable shutter acting to periodically nullify the stated action of the said light-flashing means; tensioning-means engageable with the balance wheel unit and serving to tension the hairspring thereof; and means serving to disengage the said' tensioning-means from the said balance-wheel unit substantially simultaneously with the starting of the said light-flashing means.

28. A motion-checking apparatus including in combination: means for mounting an oscillatable balance-Wheel unit having a hairspring; a source of light; a light-flashing pendulum acting to periodically flash a beam of light from the said source upon the said balance-wheel unit; a shutter-pendulum acting to periodically nullify the stated action of the said light-flashing pendulum; tensioning-means engageable with the balancewheel unit and serving to tension the hairspring thereof; and means serving to disengage the said tensioning-means from the said balance-wheel unit substantially simultaneously with the starting of the said light-flashing pendulum.

29. A motion-checking apparatus including in combination: means for mounting an object whose motion is to be checked; a source of light; movable light-flashing means acting to periodically flash a beam of light from the said source upon the object whose motion is to be checked; and means serving to start the said object in definite phase relationship with respect to the said light-flashing means.

WILLIAM BARTON EDDISON.

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