United States Patent Office @9153,896 P a @ . e r @ t e d O c t . 2 7 , 1 9 6 4 3,153,896 E4 LECTRIC CIT-OCK Theodore S. SmL@lslii, Munster, Ind., assi.anor to The Andersoia Company, a corporation of Iridiana Filed Nov. 9, 1961, Ser. No. 151,213 5 6 Claiiiis. (Cl. 58--98) This invention relates generally to a clock and more particularly to an el,-ctric clock. This application is a continuation-in-part of my co- 10 pend-ing application Serial No. 757,884, now abapdoned, which is a division of my application Serial No. 549,709, filed November 29, 1955, now Patent l@lo. 2,979,629, issued April 11, 1961, to which reference of the latter may be made for det0s of structure of subsidiary itenis 15 alluded to herein. In the clock of this invention, a pivotal oscillatory ele.- ment is arranged to drive stiitable clock mechaiiism as it oscillates, and electromechanical traisducer means are provided for driving the oscillatory such means 20 being energized in synchro-@iism with the moveme-it of the oscillatory element. The electromecharical traisducer means is preferably an electromagtielic arrangement in ,vhich the oscillatory element forms an armature of a magnetic material, such as soft iron, disposed between 25 two poles of an electromagnet, the armature being ijrged by magnetic forces into alignme-it with the magnetic fl-ux path between the poles wiien the electroinagnet is energized. The oscillatory element may be urged tov@ard a neutral 30 position by a restoring force, preferably from a suitable hairspring, and may move iii one direction from a first position through such neutral position to a second position and then in a reverse directioti back 'Llirough tiae neutral position to the f-xst positioii. The transetucer 3 5 means is preferably such that it acts generally in opposi tion to the restoring force so that when the o-,cillatory element is between the first position and the neutral pos,- tion, energization of the transducer means will urge the element to-vvard such first position while, when the ele- 0 ment is betweei the neutral position and the second position, onergization of the trar@sducer means will tirg,- tlle element toward such second position. Contact means and circuitry are controlled by movement of the oscillatory element for energ,.zing the transdi-icer means when 45 the element moves in either direction beyoiid such neutral position. The clock preferably incorporates a mechanism driven in one direction froni oscillatory movernent of the element, the drive arrangement preferably bein, such that 50 dri,,re is actuated in about the same portions of the cycle as those in which the tra@isducer m-,ans is energized to minimize any effect on the time period of the oscillatory movement. The prirnpry object of this invention is to i,)rovicle a 55 clock mechanism having a pair of ro@atabl-, shpfts, with improi,ed means whereby one shaft may be r-@ad@ly adjustably connected to the other shaft, Other objects and advantages of the invention will become apparent after the description hereinafter set forh 60 is considered in conjunction with the drawings anliexed hereto. In the drawings: FIGURE I is a top plan view of the mechanism of this invention remolied from its casing; 65 FIGURE 2 is a front eleva@ional view of the mochanism; FIGURE 3 is a top plan view of an asseinbly o-f o@ily certain elements of the mochariism of FIGURF2; 70 FIGURE 4 is a rear elevational view of the assembly of FIGURE 3; 2 FIGURE 5 is a cross-sectional view taken substantially alo-iig the line 5-5 of FIGURE 4; FIGURE 6 is a top plan view of the oscillatory arr@-iature element and associaed spring of th-, mec'qanism of FIGURE 2; FIGURE 7 is a side clevational view of the arrangeme-@it of FIGURE 6; FIGURES 8, 9 and 10 are detail views of certain portons of the m-,clianisrn of FIGURES 6 and 7; FIGURES 11 and 12 are detail views of certain elemepts of a contacting mec'--anism; FIGURES 13 and 14 are top plan views of the contacting mechanism, showing alternative positions of the element; and FIGURE 15 is a fragmetitary s,-ctional view takeii along the ola-,ic 15--ILS of FIGURE 14. '@ general, the mechanism of the clock includes a pivwal oscillatory eleme-@it 35 @.n the form of an armattire of ma@-ne,ic material movable belween a pair of pole elements 36 apd 37 of an eleetrolnagnet having an en-,rgizing coil 38. The armat,,jre element 35 is ur.-ed by a suitable spiral hairsi)ri--qg 39 to a neutral position sijch as illustrated in the plan v@'ew of FIGURE I and, when the coil 38 of the el.-clromagnet is energized, the armature 35 will be oscillated by the magnetic forces of the electromagnet into alignment with the flux betwecn it-ic poles 36 and 37. lt will be appreciat,,d that the el@ement 35 will tend to oscillate at a rate determined by its in@-rtia and the characteristics of the spring 39 aild, by ener,@;z@,'ng the efectromag-@iet co;l 38 at appropriate portio-ps of the cycle of movement of the element 35, it may be maintained in oscillatior.. Accordingly, a conlact arrangeme-@it, generally designated 40, is provided which is actuated by movement of the element 35 to control en-,rgization of the coil 38, the details of which are described hereinafter. Means @-enerally a@-e provided for tratisformin@@ the reci.-@)rocating oscillatory movement of the element 35 into rotary moven-ier@t which is used to drive the clocl.- hands throue, a suitable goer tr,)-in, as will be described. The mecha-riism of the clock may be suodorted from a forward vertical frame plate 42 and a rearward frame plate 43 wbicii are supported in fixed parallel relation to each other aiid to the clock casing by r@leans of posts 45, 46 and 9,7. The frame plates 42 and 43, and especially the rearward plate 43, are preferably of a nonniagnetic material such as brass and a pair o'l plates 48 and 49 of magnetic rnaterial, such as iron or steel, are disposed on the forward face of the rearward plate 43, adjacent opposite side portions thereof, the pla@es 48 Ind 49 having forwardly turned upper end portions 50 and 51 which may be formed to define the poles 36 and 37. There is a core element of ma.@netic material inside the coil 38 bridging plates 48 and 49 and thus conducting pulses of coil 33 to poles 36 and 37. It is sufficie-@it here to state that on@-rgizatioji of coil 38 is tri,-@ered to maiptain element 35 in oscillatio-,l. This is LCCOMplishel throiigh c:@rcu:try to said coil including make-aiid-break contacts spring biased towardengagement. Pin 160 carried by an end face of a cam 139 on shaft 98 actua'Les a leg portio.,i 153 for rnak,ng the co.itact, while cam 139 actuates leg 138 of arm l@-6 for br,-aking the contact. Both the co-Titact maki-ng and cotitpct breaking mechan;srrs areadius@lable and, combiiied with the adjustabil-ity o@-' -@)o@le pieces 36 and 37 (described below), perm't pr--cise synchronization ol' oscillatory element 35. T,ie adjust;@ilg means p.-r se are part of the subject niatter of t-@ic parent application, and reference is mide thereto for full disclosure of the details. As above ind-'@cated, mechanism is arranged to convert the oscillatory movement of the element 35 into rotatin.-

movement. This mechanism is arranged to drive a toothed side of the opening 117 and defining an opening 119 on wheel 66 which, as best shown in FIGURES 3 and 4, is secured on a shaft 67 which carries a worm 68. A specific feature of the invention is in the moanting of the shaft 67. In accordance with this feature, the end of the shaft 67 adjacent the wheel 66 is journalled by one leg 69 of a generally L-shaoed bracket 70 having a second leg 71 secured at its end against the forward face of the plate 42 by a screw 72. The bracket 70 is so formed -that, through its own inherent resiliency, the le-g 69 is urged forwardly with the inner end of the leg 71 being spaced from the plate 42, and an adjustment screw 73 extends through the inner end portion of the leg 71 and is threaded into the plate 42 so that, by adjustment of the screw 73, the leg 69 may be moved forwardly or rearwardly to thus, move the end of the shaft 67 forwardly or rearwardly, this adjustment being desirable to obtain accurate and reliable operation of the mechanism 41 as will appear hereinafter. The other end of the shaft 67 is journalled by one leg 74 of a generally L-shaped bracket 75 having a second leg 76 secured to the plate 42 by a screw 77. The plate or bracket 75 is so formed that the pressure between the leg 74 and the shaft 67 may be adjusted by means ol' the screw 77. The worm 68 (FIGURE 4) meshes with a worm wh-,el 78 which carries a pinion 79 which meshes with a gear 80 secured on a shaft 81 which carries the minute hand 34. The shaft 81 may carry a pinion 82 meshed with a wheel 83 which carries a pinion 84 meshed with a gear 85 on a sleeve 86 which may support the hour hand 33. To allow setting of the hands of the clock, there may be a frictioiial drive between the wheel 80 and the shaft 81 iii which the wheel 80 may be urged against a collar 87 on the shaft 81 by a coiled compression spring 88 actina between the wheel 80 and a collar 89 secured to the shaft 81. . The oscillatory armature element 35 (FIGURE 7) is supported on a vertical shaft 90, the upper end of which is journalled by a bearing 91 fitted into the lower end of a screw 92 threaded into a bracket 93 having ends 94 and 95 (FIGURE 2) secured by screws 96 and 97 to the flange portions 50 and 51 of the members 48 and 49. The spiral hairspring 39 (FIGURES 6 and 7) has its inner end secured in a collar 98 on the shaft 90 and its outer end secured by a locldn.a wedge 99 in an opening in a plug 100 secured by a screw 101 in an openin.- 102 in the bracket 93. For adjusting the effective action of the coiled hairspring 39, a plate 103 pivotal about the axis of the screw 92 has a do,,vnturned bifurcated portion 104 embracing a point of the outer convolution of the hairspring 39, the effective tension of th,- spring 39 being adjustable by rotation of the plate 103. To joumal the plate 103, it may have an upturned annular flange portion 105 engaged by a corrugated resilient washer 106, the washer 106 being spaced from the bracket 93 by a washer 107 with a nut 108 tbreaded on the screw. 92 to hold the washer 106 against the annular flange 105 of the plate 103. It will be appreciated, of course, that the pressure between the bearidg 91 and the upper end of the shaft 90 may be adjusted by means of the screw 92. As shown in FIGURE 7, the lower end of the shaft 90 is journalled in a bearing plug 109 carried by a collar 110 which is press-fitted into a lug portion Ill of the rearward frame plate 43. The mechanism for transforming the oscillatory movement of the element 35 into rotary movement comprises the toothed wheel 66 above described and a device 112 secured on the shaft 90 and illustrated in FIGURES 7 and 10. The device 112 comprises a pair of vertically spaced discs 113 and 114 secured on a hub 115 which is in turn secured on the shaft 90, the upper disc 114 having @in annulatly tipwardly projecting struckout portion 116 defin-ing an opening 117 therein, and the lower disc 113 haviiig a struckout portion 118 extending upwardly to one the peridhery of the disc 113. In operation, a tooth of the wheel 66 may be disposed between the discs 113 and 114; and when the shaft 90 is rotated in one direction (clockwise, as viewed from below), the portioii li@'S of the disc 113 will cammingly engage such tooth and force it downwardly through the opeiiing 119. The next tooth of the wheel 66 will then be disposed just abbve the upper disc 114; and when the lo shaft 90 is rotated in a reverse direction (counterclockwise, as viewed from below), the poriion 116 of the upper disc 114 will cammingly engage such tooth and force it downwardly through the opening 117 into the st)ace between the discs 114 and 113. This cycle will be 15 repeated with each oscillation of the shaft 90 and it will be appreciated that a drive of the wheel 66 in one directioii is aohieved, It might here be noted that, by virtue bf the support arraiigement ior the end of the shaft 67 adjacent the 20 wheel 66, the position of the wheel 66 relative to the device 112 may be readily adjusted so as to obtain efficient operation of the motion-converting mechanism. The poles 36 and 37 are constructed so that they may be readily adjusted into optimum relation to the armature 25 e.ement 35. The flange portions 50 and 51 of the members 43 and 49, which flange portions define the poles 36 and 37, have arcuate edgescomplementary to the periphery of the element 35, and slots are formed in the flange portions 50 and 51 in spaced generally parallel 30 relation to said edges. By inserting the blade of ascrewdriver or similar tool into the slots, the edges may be readily brought into properly spaced relation to the periphery of the element 35 as disclosed in detail in the parent application. 35 A highly important feature of the structure is in the construction of the contact means 40 for energizing the coil 38 in synchronism with the oscillatory movement of the element 35. Iii particular, the contact means 40 (FIGURES 13 and 14) comprises a movable contact 40 124 engageable with a stationary contact 125, the contact 125 being connected to the plate 64 and thus to one side of the coil 38 with the movable contact 124 being electrically connected to the frame of the mechanism so that when the contact 124 is engaged with the contact 125, 45 a circuit is completed through the coil 38. The movable contact 124 is preferably formed of a separate piece of flat stock of a suitable electric contact material, such as silver or platinum, and is fixedly secured by welding or soldering to a relatively rigid actuating arm 50 126. The contact 124 actually lies normal to the plane of the arrii 126 and depends therefrom so that only the free edge of the contact proper is utilized as the contacting area, as will be later apparent. The arm 126 is riveted, as at 127, or otherwise secured to one end of a flat spring 55 128, the other end of the spring being interposed between a pair of spring plates 128a and 128b secured to a portion 129 of the rearward frame plate 43 by a screw 130. A second screw 131 is threadedly received by the plate portion 129 and serves to urge the offset outer ends of the 60 spring piates 123a and 12$b toward the frame plate portion 129. Obviously, adjustment of the screw 131 toward the portion 129 will urge the contact 124 downwardly (as viewed in FIGURE 13) to increase the contact pressure between the contacts 124 and 125. Conversely, 65 loosening of the screw 131 will relieve the contact pressure. The stationary, but adjustable contact 125 is similar to the contact 124 and is ia separate contact element sectired to a resilient arm 132 having a portion 133 70 secured to the terrninal post 59, an insulating washer 134 being disposed between the portion 133 and the member 49. A second arm 135 of configuration similar to the arm 132, btit rigid throughout its length@ has a portion in spaced relation in front of the arm 132 and a p6rtion 75 136 disposed between the portion 133 of the member,

5 132 and the plate 64 on the terminal post 59 to complete an electrical circuit therebetween. A screw 137 extends through the arm 132 and is threaded into the arm 135 so that, by rotation of the screw 137, the position of the fixed contact 125 r@iay be adjtisted. It will be noted from FIGURE 15 that the contacting edges of the contacts 124 and 125 lie normal to one another, and the resulting very small contact area requires very little contact pressure -thereby redticing the load on the contactactuating mechanism. The contact arm 126 is so supported that it urges the contact 124 into epgagement with the co-iitact 125. To disengage th-, contact 124 from the contact 125, the arm 126 has an end portion 138 actuated by a cam member 139 affixed to the shaft 90. The cam 139 has a cylindrical surface portion 1,1,0 concentric to the axis of the sh,Lft 90 and a pair of coplanar flat surfaces 141 and 142. When the shaft 90 rotates in a counterclockwise direction, the surface 140 may engage the end portion 138 of the arm 126 to move tic contact 124 out of eng,q.gement with the contact 125, as shown in FIGURE 13; and when the shaft 90 is rotated in a cloelwise direction, and portion 133 of arm 126 is over either coplaiiar surilace 141 or 142, as shown in FIGURE 14, arm 126 is allowed to move so as to engage the contact 124 with th-- contact 125 after which the surface 140 may again engage t@e end portion 138 of th@- arm 126 to, dis-.n.-a.-e the contact 124 from the contact 125. M,--ans are provided for releasably maintaining the arm 126 in a position with the contacts d;sengaged. In particular (FIGURE 12), a slot 143 is formed in the arm 126 in proximity to the contact 124 and a res@@lient control arm 144 is arranged to frictionally engage one side edge of the slot to maintain the arm in a position w.;th the contacts disengaged when it is moved by the cam faces 141, 142 into such a position. The control arm 144 has a supporti-@i.- leg or flange portion 145 exte-tiding normally from its rearward end, the flange portion 145 being disposed be'@we-.n one leg 146 of a generally L-shaped clamping member 147 and one leg 148 of a genera-Ily L-shaped portion 149 of a support braclcet getierally designated by reference numeral 150. A screw 150a extends through the flan,-e portion 146 and the leg 145 and is tlireaded into the leg 148 to rigidly secure the flange portion 145 to the bracket 150 (FIGURE 13). To adjust the frictional en,@agement between the control arm 144 and the ed-@ of the slot 143 in the arrn 126, a rearward end portion of the arm 144 (referring especially to FIGURES 13 and 14) is disposed betweerl- a first arr@i 151 of the claw-ping member 147 and a second leg 152 of the L-sfiap,-d portion 149 of tqe bracket 150 with a screw 153 extending through the le.- 151 and threaded into the leg 152, the control arm 144 bein.@ moved toward or away from the leg 152 by rotation of the screw 153 to adjust the frictional en.-agement between the arm 144 and that e@ge of the @slot 143 in the arm 126 which is remote from the contact 124. For actuating the control arrn 144 to release the contact arm 126 so that the contacts 12@,l and 125 may abut, the arm 144 has a forwardly projecting flange 154 at its lower end (FIGURE 11). The ffange 154 engages a bas@ portion 156 of a rockable or reciprocable release plate 157 which has an integral leg portion 158 extending throtigh an opening 159 in the control braelcet 150 to lie in tl-ic path of an actuatin@ pin 160 (FIGURE 8) carried by the cam member 139. The flange 154 of the control arm leA4 has a pair of Projections 161 and 162 extendin.a into slots 163 and 16i in the base portion 156 of the plate 157 to maintain the plate 157 and the arm 144 in proper relation. In operation, -vvhen the shaft 90 rotates in one direction, for exaniple, clockwise as viewed in FIGURES 13 and 14, the pin 160 will enga.-e the le@- 153 of the plate 157 to rock the plate about the point of engagement of 6 the rearward edge ol' the base portion 156 thereof with the portion 155 of the support bracket 150 and the base portion 156 will serve to move the forward end of the control arm 14.4 to the right, as illustrated in FIGURE 14, rnoving the arni 144 to reduce frictional engagement wit'i the edge of the slot 143 in the contact arm 126 to thus release the arm 126 and allow the contact 124 to engage the contact 125. Similarly, when the shaft 90 is rotated in a counterclockwis-. direction, the pin 160 may 1( engage the leg 158 of the device 157 to rock the device about ttie point of engagement of the base portion 156 with the portion 155 of the support braclcet 150 iand thus move the co-iitrol arm 144 and reduce frictional engagement with the edge of the slot 143 and thus again allow 15 movement of the arm 126 to engage the contact 124 with the con@Lact 125. It will, accord,'@nrly, be appreciated that the disengagement or opening of the contacts 124, 125 is controlled by the engagcment of the cam f aces 141, 142 with the 20 end portion 138 of the arm 126 while engagement or cl@osing of the contacts 124, 125 is controlled by the operat@'.on of the rockable device 157 which also is respopsive to oscillation of the shaft 90. The opening time can be adjusted by adjusting th-, position of the screw 25 137, this adjustment being independent of the adjustment of th-. closing time. To eqtialize the closing time of t'@ie contacts 124 and 125 in each oscillatory cycle of the shaft 90, the relative positions of the portions 149, 155 of the support bracket 30 150 in,,y be adjusted. For this purpose, the support bracket 11,70 has a base portion 165 havin.- one end inte-rally secured to the portions 149 and 155 with the other end ther-@of secured ti.-htly against the rearward face of the rearward frame plate 43 by a screw 166 '@ 5 which extends tlirough an opening in the base por-tion l@65 of the bracket 150 (FIGURE 1). The base portion 165 of the bracket 150 is so formed that the end thereof adjacent the portions 1,1,9, 155 is urged by the inherent resiliency of the portion 165 in a rear-ward direction away 40 from the rearward i'ace of tie rearward frame plate 43, and a screw 167 extends through the portion 165 iadjacent the portions 149, 155 and is threaded into the frame plate 43. Rot-,ition of the screw 167 adjusts the leg 152 to position the release plate 157 relative to the cam plate 45 139 and particularly with relat;on to the cam plate pin 160. By this adjustment, the plate 157 can be set so that @,he contacts 124, 125 are closed for the same length of time regardless of the direction of oscillation of the shaft 90. 50 As mentioned above, the screw 153 is used to initially set the frictional pressure betnveen the control @arm 144 and the edge of the slot 143 in the contact arm 126. The support bracket 150 is assembled on the frame plate 43 by the screws 166, 167, 169 and 170 @to retain the release E5 pla'Le 157 between the leg 152 and the end 154 of the control arm 144. Th-- release plate 157 is free to be rocked by the pin 160, and a certain degree of such rockin.@ motion can b-. accommodated wittiout releasing the contact arm 126. The time of closing of the con60 tacts 124 and 125 can thus be regulated by varying the free rocking motion of the plate 157, i.e., the arnount of move@nent of th,- plate 157 which is tolerated before release of the arm 126. For this purpose, the openin.- in the base port;on 165 of the support bracket 150 through 65 wp@ich the screw 166 extends is in the form of a slot to al',ow movement of the bracket 150 to the right or left, as viewed in FIGURE 1, for example. To con'trol this movement, the base portion 165 of the support bracket 150 has a forwardly turned flange portion 163 adjacent 70 one ed.-C of the frame plate 43 and a first adjustment screw 169 extends through the fiange portion 168 and is threaded into the plate 43 with a second adjustment screw 170 threaded through the Range portion 168 and en.-ageable with the edge of the plate 43. Thus, by 75 adjustment of the screws 169 and 170, the support bracket

150 may be moved to the right or to the left, as viewed in FIGURE 19. After such adjustment, the bracket can be locked in position by the screws 170, 169 and 166. Operation 5 For reasons to be explained in detail later, the normal position of the contacts 124 and 125 is closed, i.e., the positions of FIGURE 14. When the clock 30 is energized, as b-y connecting a suitable direct current source, such as a battery, between the terminal post 59 and the 10 frame, of the inechanism, the coil 38 will be energ@'zed. The armature elenient 35 will be moved in one or the other dirdetion of oscillation, the direellion of initial movement depending upon the POSitiOD. of the armature relative to the pole pieces 36 and 37. 15 The contacts 124 and 125 remain closed for a relatively limited displacement of the shaft 90 from its neutral position at which the armature 35 is positioned symrhetrically between the pole pieces 36 and 37. A relatively greater displacement oil the shaft 90 is reqliired tO 20 opon the contacts by the cai-n faces 141, 142 of the cam 139. I Upon deenergization of the device, the armature 35 continues to oscillate, because of its inertia, the arcuate displacement of the armature diminishing. Initially upon 25 deenergization, the cam faces 141 and 142 and the pin 160 sequentially open and close the contacts 124, 125, but as the magnitude of armature displacement becomes less, the cam faces 141 and 142 do not open the contacts 124, 125, although the pin 160 will rock the re30 lease plate 157 to close the contacts. Thus, the contacts remain closed when the arniature comes to rest. Of course, the armature is never exactly centralized between the pole pieces, but will lie approximately centrally therebetween. This random positioning of the 35 armature 35 causes the armature to move initially in accordance with its position and without effect upon t'ne operation of the device. Considering first clockwise movement of the - ,irmLture element 35, the cam surface 142 of the cam mem- Ilu ber 139 will engage the end portion 138 of the contact arm 126 to move the contact 124 out of erigagement with the contact 125, and thus deenergize the coil 38. Rotation of the armature element 35 may continue in a clockwise direction from the kinetic en-@rgy resulting 45 from its motion, but evelitually due to the restorin,@ force of the spring 39, the armature element 35 will be urged back in a counterclockwise direction. When the armature element 35 and shaft 90 rotate to a positioli with the face 142 of the cam member 139 opposite the end por50 tion 138 of the contact arm 126, the arm 126 will no,, move back to engage the contact 124 with the contact 125, due to the frictional engagement of the arm 144 with the edge of the slot 143 in the contact arm 126. However, with further counterclockwise movement of the 55 armature element 35, the pin 160 will engige the leg 158 of the rockable device 157 to effect a clockwise moverhent of the device about its forward edge portion to move the forward end of the control arm 144 so as to reduce the frictional engagement pressure with the edge ro 6f the slot 143 and allow the contact arm 126 to move to engage the contact 124 with the contact 125. This will reenergize the coil 38 of the electromagnet to exert a force which cooperates with the kinetic ener.-y of the element 35 in effecting further counterclockwise 6,5 movement of the element 35. With such further counterclockwise movem,-nt, the face 141 of the cam member 139 will engage the end portion 138 of the contact arm 126 to move the arm 126 to a positiod such as illustrated in FIGURE 13 and disenga@e 7o the contact 124 from the contact 125. The countercloe,kwise movement will continue uiitil stopped by the iiicreasing force of the spring 39, after which the armature element 35 will move back in a clockwise direction from the force of the spring 39. 75 Iri this clockwise moveme,.it, when the shaft 90 reaches Ei position such that the face 141 of the cam niember 139 is opposite the end portion 138 of the contact arm 126, the arm 126 will not move into contact-erigaging position due to the frictional engagement between the control arm 144, engagement of the control arm 144 with the edge of the slot 143, and the contacts will not be reengaged until with further clockw,ise movement the pin 160 actuates -the rockdble device 157. This cycle will, of course, be repeated over and over again, and the iilovement will oscillate at an amplitude dependent upon the relation of the energy supplied by the electromagnet to the energy dissipated as heat from ftiction, etc. While the amplitude of oscillation may vary with variations in the slipply of voltage, the elapsed time of each cycle of operatiori will remain the same so that the accuracy of the instrument will not be affected. It should be noted that the mechanism 41 which con@orts the oscillatory nioveinent of the shaft 90 into, rotational movement of the wheel 66 is so related to thf, contacting assembly 40 that the drive is imparted to the el 6 during substantially the same portioi-is of the 6yele that the coil 38 is ener.-ized. Accordingly, t',e effect on the natural vibratory movement of the element 35 is niinimized to thiis minimize the eff-ect on the accuracy of operation of the instr-,iment. By virttie of the contact arran I @emenL of this invention, it is possible to accurately aqjust the portions of each cycle when the contacts are closed so as to ichieve this highly accurate operation. When the clock is disconnected from the source of electricity, the electromagnet will, of course, no longer imiaart driving force to the oscillatory element 35 and the amplitude of oscillation will gradually reduce. The friction between the end 138 of the contact arm 126 and the cam member 139 is low enough relative to the restoring force exerted by the spring 39 that if the oscillatory elemeiit 35 swings in either direction to an extent ufficient to open the contacts, it will swing back in the reverse direction to an extent sufficient to actuate the device 157 and close the contacts. Accordingly, if the clock is deenergized, ttie oscillatory element will ultimately reach a position with the contacts closed so that ivhen the clock is reenergized, the coil 33 will be energized and operation of the oscillatory mechaiiism mtist be initiated. Hence, there is no "dead" position of the mechanism. Having thus described my invention, it is obvious that various modifications may be made in the same witliout departing from the spirit of the invention; and, therefore, I do not wish to be Linderstood as limiting myself to the exact forms, constrtictions, arrangernents a-id combin-ations of parts h@-rein shown and described. 1