US754397A - Electric clock. - Google Patents

Description

PATENTED MAR. 8, 1904.

G. S. TIFFANY.

ELECTRIC CLOCK.

APPLIOATIOK nun HOV. an. 1901.

no 30mm.

eeml l wmrssses latented March a, 1904.

.;if V 'UNITEDiSTATES PATENT OFFICE- fsoaess. TIFFANY,- or BROOKLYN, NEW YORK, ASSIGNOR OF ONE-HALF a: 1 JAMES VAN INWAGEN, OF CHICAGQILLl-NWS ELECTRIC CLOCK.

,sPncIncA'r IoN forming pm of: Letters Patent him 754,397, dated March a. 1904.

x r Appliqatioii filed Iiuveinber 30,1901. Suit-1N0. 4,237, on model.)

1'0 all'wh/om 'it'nuty concern;

'Be'itknow'n that I, (inolion s ltiFEANY a citizen'of the United States of America, res1d' ing atBr-ookly-n', inlthe county ofKings, in the a State of New, York, have invented certain new and useful Improvements in Electric Clocks,

( of whichthefollowing is a specification.

The object of this. invention is'to provide an electric elockwhich will keep time continuously foixalong' period--say ayear, more or les's%with9ut requiring attention, except in c ase'0f accident, and with a verysmall current consumption. 'To-this end the clock is-madc very simple and comprises theadaptatio n of a torsional pendulum to the controlof an electromagnetic driving mechamsm n such a manner as to leave the pendulum separate from the driving mechanism, whereby it sreh'eved of I -the work ofmechanicallyactuat ng the parts of said mechanism :and is free to rotate independently of the movement of the armature constituting a part of said -mechanism. 'By this means the beneiit oi' the long-period beats incident to the torsional pendulum is obtained withoutencumbering said pendulum with mechanism which will impair its regular and efiicient action. The current consumption is minimized by, the long-period beats, the eurrent being used fortan instant only near the middle of each heat to impulse the penduhnnl The variation in frictional resistance of the driving mechanism due to changes of weather and changes in conditions of lubrication cannot be'imparted to the pendulum and create irregularity thereof.

- Eigurel of theaccom )anying drawings represents a rear elevation of this clock, a few pieces being broken out to secure a better illustration. Fig.- 2 represents a side elevation thereof looking from the right of Fig. 1, some parts being broken out.- Fig. 3 represents, on an enlarged scale, a planview of the armature with its contact-studs and the pendulum-rod with its contact-arm.

The same reference-numbers are used in all figures to designate the same parts.

The mechanism of this clock may be supported-in a clock-trample of any suitable construction. In the form in which the invention is embodied in the accompanyingd'rawings the 5 frame comprises a back 'plateflO, having on its" frontface 'posts,as lland 12, near i is periphery, and on its rear face at its top an elongated pen-' dulum-post 13, insulated from the back plate,

a shorter post 14 disposed near the pend uluin- 5 5 post and alsoinsulated from the back plateuuid.

a post J5 disposed below and on the other side of a vei'tical diam etrieal line passing through the pendulum-post. A clock-dial 20 is secured to the posts, as 11 and 12, in frontof the back plate .10. This dial may be of' any suitable construction.-

. ,A bracket 2E0, composed of non-magnetic material, is secured 'by means of screws 31 and 32 or otherwise to the lower portion of the back plate 10 on the rear face thereof. The bracket'30 extends upward and is recessed above its; place of attachment, forming a space 33 ibetween it and the back plate, and ithas a laterally-projeeting ear 34: opposite the center 7 of the back plate 10 and two laterally-projecting' cars 35 and 36 below the ear 34 and on a horizontal line with each other.

A central arbor :30 is supported in a hearing of the baek plate l0 and at its inner extremity in a bearing of the car 34 of the bracket 3U. 'lhis arbor is provided with a lixed collar 5i near its inner end and with a pinion 52 between the bark plate and the dial. it linntehand (i0 is secured to the outer end of. the arbor in frontof the dial 2". An hour band sleeve 70 surroumls the arbor 50 in the usual manner and extends through thedial 20, being. provided at its outer end in front of said dial with an hour-hand 80 and at its 35 inner end between the dial and back plate-l0 with a gear-wheel T'l.

An auxiliary arbor JU, supported in suitable bearings, is disposed between the back plate and the dial to one side of the central 0 arbor 50. The auxiliary arbor is provided with a gear-wheel .H, which meshes with a pinion 52 of the central arbor and is also provided with a pinion 92, which meshes with the gear-wheel T1 of the sleeve 70, carrying the hour-hand.- '.lhe motion of the arbor oi the minute-hand communicated to the sleeve of the hour-hand by this. or any su table means.

tral arbor 50 and extends into the recess-33 of the bracket and is held against the collar 51 by a spring-clamp 101. p

- An electromagnet of any suitable construction'is secured to the back plate at one side of the center thereof. In the form herein shown this magnet comprises cores 110 and 120, and spools or helices 13 0 and 140are disposed thereon. The cores are supported at one'end in the bracket-30 and are secured thereto by set- screws 112 and 122 and are connected at their other end by a yoke 40. The ends 111 and 121, wl'1ich extend through the bracket 30, constitute the poles of the mag-. 'net.

These cores are preferably composed of mild steel, so as to hold residual magnetism after the current is cut off.

An armature 150 ishinged to the ears 35 and 36 of the bracket '30-.below the electromagnet and extends upward past the projecting pole ends of said magnet, with which it is adapted to form contact when the cores are magnetized. The armature is provided with means for drawing it away from the magnet. The means shown consists of a spring 160, connected at one end to an arm 41, depending from the bracket 40, and at the other end to the armature 150, below the pivot. thereof, 7 and this spring tends to swing the-armature away from the magnet; A pawl 170 is pivoted on an arm 158 at the upper end of said armature and engages teeth of the ratchetwheel 100. An adjusting-screw 16 engages post 15 and serves as a stopaga-inst'which the pawl abuts on completing its stroke whereby the action of the spring 160 is.controlled.' A spring-check pawl 180 engages the ratchetwheel100 and serves to hold it in positionv during the retraction of the pawl 170.

The armature 150 is provided at or near its upper end with two electric contacts or contact-studs 151- and 152. disposed apart from each other on opposite sides of a vertical line passing through the center arbor. These studs are insulated from the armature and may be secured to the armature by means of a shortcross-bar153,001nposed of insulating material and disposed at the upper end thereof. The armature also carries a third contact 157, preferably attached to a plate 156, disposed on a stud 154, secured to and insulated from the armature 150. A spring 155 is also disposed on the stud 154 and in electrical con nection with said armature, but insulated at its point of attachment from the plate 156. This spring rests normally against the contact 157 and serves to close the circuit through the plate 156. This spring extends beyond said plate and is adapted to engage at its outer end a contact 190, which is preferably adjustable on the insulated post 14. When the arn1a- A ratchet-wheel 100 is disposed on the cen ployed.

; of the energizing-circuit and is thereby separated from the contact 157 of the plate 156 of the releasing-circuit. Thespring thus acts in. connection with these parts as an automatic switch to shift the current from one circuit to the other, and the contact 190 thus serves as a circuitbreaker for the releasing-circuit.

A suitable electric source is disposed on or connected with the.clock--as, for instance, a battery 200. A conductor 201 connects the positive polethereof with the contact 151 on the armature, a conductor 202 connects'the pendulum-post 13-with the helix 130 of the electromagnet, a conductor 203 connects the helix 130 with the helix 140, a conductor 204 connects the helix 140 with the heel 10, and conductor 205 connects the armature with the spring 155, a conductor 9.06 connects the contact 152 with the negative pole of the battery, a conductor 207 connects the plate 156 with conductor 206, and a conductor 208, provided with a resistance 209, connects the contact 190 with the positive conductor 201..

A shunt-circuit 2.10 is connected with the coils of the electromagnet and provided w h a resistance-coil 211, which imparts t: re shunt-circuit a considerably higher resistance than that of the magnet -A compensating pendulum is preferably employed in connection with this clock The pendulum-shown comprises a torsional pendu- .lu'rn support or rod 220, suspended from the pendulumpost'-13 and a pendulum-bob 23 0,

" whose are of oscillation is horizontal, securedto the lower end of said rod. The pendulumrod is composed ofa flatelastic metallic strip orwire or strands ofwire or other material adapted to receive and resist a torsional force.

This pendulum-rod has means for completing an electric circuit through its main body orotherwiseand is provided with acontact-arm 221, secured at one end to said rod and projecting at the other end between the contactstuds 151 and 152 of the armature. As. the pendulum-rod oscillates the arm 221 touches one or the other of said contacts, preferably by means of an upright stud 222, secured to the free end thereof.

he pendulum-bob 230 comprises ahorizontal coupling-bar 231, weights 232 and 233 adjustable at opposite ends of said bar, and a spring-clip 234, suspended from the pend ulumrod and connected with said bar between said weights. The weights are preferably spherical in form and provided with diametrical holes, into which the opposite ends of the bar enter. .These weights are preferably adjustable on the coupling-bar to regulate the torsional swingof the pendulum and to compensate for variations in the elasticity of the tor sional support from changes oftemperature. Any suitable means of ad ustmentmay no emhe means shown consist of screws ion 235 and 236, which engage screw-threaded holes in the ends of the bar and serve as stops for the weights. These screws render the coupling-bar extensible. The spring-clip 234 is preferably in the form of an expansible fork. The coupling-bar extends through holes in the legs of the fork, and the latter bear against'the weights and hold them apart from each other in contact with the stops 235 and 236; The pendulum is regulated to increase the speed of its beats by adjusting-the weights nearer together and to decrease the frequency of its oscillations by moving them farther apart. This adjustment is readily ef- 'fected ,by means of said adjusting screws or steps; To-avoid-variations due to changes in temperature and" to secure uniform action of the pendulum, the parts of the bob are so constructed as to compensate for such differences. The cou fling-bar- 231 is composedof a material which expands less for a given increase in temperature than the -material of which theweightsfare composed. For instance, the

the weights expand inwardly the required extent to maintain the normal relation between the weights. The parts of the pendulum may be so proportioned as to compensate for variations in the length or stiffness of the torsional wire due to variations in temperature.

The operation of the clock will now be de-' scribed. Assuming the armature 150 tobe away from the electromagnct 130 1 10 and the f' pendulum contact 221 touching the armature contact 151, the current takes the following course constituting the energizing-circuit:

from the positive pole of the battery 200 to v the contact 151 -on the armature 150,'thencc through thecontact-arm 221, thence through the torsional pendulum rod 220, thence.

throughthe pendulum-post 13, thence through the conductor 202, thence through the coil 130, thence through the conductor 203, thence through the coil 140, thence through the conductor 2-04, thence through the yoke 40, thence through the magnet-cores 110 and 120, thence through the bracket 30, thence through the pivot of the armature, thence through the armature 150, thence through the contactspring 155, thence through the contactplate 156 thence through the conductor 206 to the positive pole of the battery. the current will leak through the spark-coil A small portion of 211, which is ina shunt around the magnet. The electromagnet being thus energized by the. passage of the current through the coils 130 140 attracts the arniatuie 150 and the latter swings into contact with the poles 111 and 121, dragging its pawl 170 over the teeth of the ratchet-wheel 100 and assuming the position shown in Fig. 1. In this movement of the armature the spring 155 engages the contact 190 and is thereby bent away from the contact 157, whereby the 'circuit is broken. The armature will, however, remain in contact with the magnet until the current is reversed, owing to the residual magnetism of the steel cores. This swinging oi the armature toward the magnet imparts a torsional movement to the pendulum in the dircc'tion of the arrow .head 1, construed as in perspective, through the arm 221, attached to the penduhim-rod 220. This movement is not, however, imparted to the pendulum instantaneouslyl'. The pendulum being separate from the driving mechanism and independent of the movement of the armature, except to receive its impulses therefrom, the momentum impartedto it on the previous outward move-- ment at the armature will cause it to continue its rotation in the direction of the arrow-head 2 against the flexibility of its contact-aim and I the torsion of its rod fora substantial period in the same direction after the swinging of the armature. After the resistance of the rod and contact overcomes the momentum-of the bob the rotation of the pendulum is reversed and the arm 221 is caused to swing away from the armature contact 151 over against the armature-contact 152, and the circuit is then closed through the latter. The current then passes through thefollowing course constituting the releasing-circuit-to W1l],'fl'0l'1l the positive pole of the battery 200 through the conductor 201, thence through the conductor 208, incl uding the resistance 209, to the contact 190 in the stud 14, thencethrough the spring 155 to the armature 150, thence through the bracket 30,-thcnce through the cores and 111 of the magnet, thence through the conductor 202, thence tlirohgh the penduluni-post 1?), thence through the pendulum-Rod 220,thence through the arm 221 thereon, thence through the stud 156, thenccthroughthe jconductor 206 to the negative pole of the battery. 'llmcourscof the current through'themagnct is thus reversed, and the polarity of the magnet thereby changed, whereby its. residual magnetism is weakened or neutralized. The spring 160 then withdraws the armature from the magnet and causes the pawl 170 to impart a step movement to the ratchet-wheel 100 and then come to a stop against the stud 16. The movement of the ratchet-wheel turns the hands of the clock the required distance for a single impulse. The outward spring of the armature separates the spring from the contact 190, breaking the releasing-circuit and permitting said spring to rest against the contact 157 on the'platc 156 of the energizingcircuit preparatory to the re formation of said energizing-circuit-by;the subsequent swing of the pendulum. This swinging of the armature toward the leftimparts through the arm 221cm the pendulum-rod 220 a rotary impulse to the pendulum in the direction of the arrow-head 2, and after thetorsio'nal action of the pendulum has overcome the momentum of theprevious impulse the arm 221 swings away from 'theystud 1:52 into contact with the stud 151,whereby the circuit is again restored in the direction before described and another impulse imparted to the pendulum'in'the direction of the arrow-head 1. This arrangement of contacts thus operates as a pole-changer with means for-opening the battery-circuit after each'reversal of the current and movement of the armature. The object of the'resistance 209 is to weaken the current for releasing the armature, as a much weaker current issufiicient to neutralize the residual charge than that necessary for energizing the -magnet for"'-throwing up the armature. The resistance 211, which is' in par-.

allel with the magnetcoils, affords a'path for the discharge-current of the magnet when the circuit of the battery and the .magnet is opened, thus avoiding sparking at the contact. l

It will be seen from the foregoing that for every s ing of the pendulum there is a movement of the armature, and this movement of the armature will always givethe pendulum an impulse tending tokeep it in motion, and every alternate motion of the pendulum will propel the wheel of the. clock the distance of one tooth. l Consequently il1" OId8l that the clock may keep accurate time it is merely necessary ,to' adjust the beat of the pendulum to the number of teeth in said wheel. It will also be observed that-the pendulum has no mechanical work to perform in'controlling' the clock, and consequently the frictional error is reduced to a minimum, .being reduced practically tothe resistance of the air.'

I find that a'pendulum havingbeats of five seconds each and a wheel having three hun dred and sixty teetl1,.mov ing onetooth every ten seconds, will give good results in a small clock. a,

The mechanism may be varied in construction and arrangement without departing from the scope of this invention.

The battery -circuit being opened imme cliately after each effective action .of the magnet and the torsional pendulum being permitted to oscillate in both directions of rotation after the circuit is intervals between the closings of the circuit are prolonged, it follows that the current conisumption-is very small. As a matter of fact it is' scarcely measurable. As the pendulum 18 separate from the driving mechanism proper .provided with an electric reversed, whereby the and acts merely as a contact device to control said mechanism, it is not retarded or made irregular in its action by the varying friction and irregularities of the mechanical devices constituting a part of said mechanism.

1 claim as my inventionv 1. The combination of a clock-train, a torsional pendulum, and an electromagnetic clocking as a circuit-closer for said electroma;

netie driving mechanism.

3. The combination ofaclock-train, a clocktra'in-driving mechanism therefor comprising an armature,- an electromagnet for actuating said mechanism, alternate reversing electric circuits for energizing said magnet, and aregulating torsional pendulum independent of said driving mechanism and provided with an electric contact for controlling said circuits, said pendulum being free to rotate independently of the movement'of said armature.

4. The combination of a clock-train, an elect-romagnet, an armature movable into contact with said magnet, mechanism operated by said armature for driving said clock-train, an electric circuit for energizing said magnet to attract said armature, an electric circuit for passing a reduced electric current through said netism, mechanical me ms for swinging said armature out of contact with. said. magnet, a pendulum, two contacts adapted to be en gaged by said pendulum for closing the re speetive circuits at alternate beats of the pendulum, and a circuit-breaker adapted to instantly break the energizing-circuiton the closure of the armature against the magnet.

5. The combination of a clockitrai-n, an electromagnet, an armature movable into 'contact with said magnet, mechanism operated by said armature for driving said clock-train, an electric circuit for energizing said magnet to attract said armature, an electric circuit for passing a reduced electric current through said magnet in a direction reverse to that of'the m agnet in a direction reverse to that-0f the i energizing-circuit to e immate residual magenergizing-circuit to eliminate residual magnetism. mechanical means for swinging said armature out of contact with said magnet, a pendulum provided with an electric contact, two contacts belonging respectively to said circuits and engaged said pendulum for f closing either circuit, .and automatic means adapted toinstantly break the-energizing-circuit on' the closureyofthe armature against the magnet.

6. The combination of a clock-train, an electromagnet, anarmature movable into contact with said magnet, mechanism operated by said armature for'driving said clock-train, alternate reversing electric circuits, mechanical means for swinging-said armature'out of contact with said magnet, a' torsional pendulum provided with an e'iectric contact, two eontactsmounted'on said armature and adaptedmonnted o'n said armature" and composed of pendulum.

7. The combination ofa clock-train, an elec-v tromagnet, an armature movable into contact to be engaged by saidpendulum for closing the respective 'ci'rcuits,,a third contact falso separable parts respectively connectible with said circuits, and a device adapted io'separate said parts'to open one'of saidcircuits imme .diately after the-closing thereof and-to form a connection with thief-other circuit preparatory to its being closed-by the return of the with said magnet,.mechani sm operated by said armature-for driving said clock-train, an elec- 'tric circuit for energizing said. magnet-to at- "tract said armature, an electric-circuit for passing a reduced-electric current through said magnet in a direction-reverse to that of the energizing-circuit" to eliminate residual magnetism, "mechanical means; for swinging said armature out of contact with said mag-- net, a pendulum provided with an electric contact, two contacts mounted on said armaturea'ndad aptcd to be engaged by said pendulumforclosing therespective circuits, a third contact also mounted, on said armature and composed of separable parts respectively connectible with said circuits, and adevice adapted-to separate said parts for opening the energizing-circuit immediately after the closing thereof to form a connection with the releas-' ing-circuit preparatory. to its being-closed by m the returnof the pendulum. I

- 8. The combination of'a clock-train, a driving mechanism therefor, an electromagnet for actuating said mechanism, alternate reversing electric circuits for energizing-said magnet, pole-changing contacts separate from the pendulum, and connecting with said circuits, re spectivcly, and a regulating torsionaljpendw lum provided with an electric contact adapted to operate in connection with said pole-chang-' circuits. i 9. The combination of a (JlOCk-illfilll, a torsional pendulum, an arm fixed to said penduing contacts toopem} close and reverse said lum and constituting an electric contact, an

armature provided with two contacts between which said arm projects, means for moving said at turn m one direction, an clectromag 5 10. The combination of net for moving it in the opposite direction,- intermediate' devices between said armature and clock-train, and alternategelectric circuits, connected respectively. witlr said armature.-

actuating. said clock-'traimandf alternate w versing electriccircuits connected respectively with said armature-contacts and including the coils of saidlelectromagnet.

11. The combination of a torsional pendulum,- mechanism foractuating said train and imparting impulsesto said.pcndu-.

lum," an electromagnet. for "operating said mechanism, electric circuits controlled-1 by said pendulum for energizing said magnet,

- and'ashunt-circuit connected with themagnetcoils and including a resistance.

12. The combination of a central arbor carjrying a -minnte-hand, a sleeve on saidarbor carrying an hour-hand, a train between said arbor and sleeve, alarge ratchet-wheelon-said central arbor,-a torsional pendulum, a contact-arm connected with said pendulum, an armature provided with two contacts between which. said arm projects, means for movingsaid armature in one direction, an electromagnet for moving it in the opposite direction, a pawhconnected with said armature for'actuating said large ratchet-wheehand electric connections adapted to close the'circnit through the'electromagnet byway of either of said armature-cohtacts. 13. The combination of a central arbor carsaid central arbor, a torsional pendulum, a1

contact-arm connectedwith said pendulum,

anarmature provided with two contacts between which said arm projects, means for mov-' ing said armature in one direction, an electromagnet for moving it in the opposite direc-' tion', a'p'awl connected with said armature for actuatingsaid large ratche.t-wl1eel, a stop for magnet lay-way of either of said armature-con- 14. Theconibination ofa'clock-train, adrivsaidarmature, andrelectric connections adapt- .ed to close the circuitthrough the electroing mechanism thercimyan electromagnet for Y, actuating said mechanism, electric. means for-1 energizing said mngnehandn pendulum comprising a pendent torsional rod provided with a contact-arm, a horizontal coupling-bar sue: pended from said rod. and weights adjustable on said bar, the rod and weights being com,-

105, ryin'g a minute-hand, a sleeve on arbor carrymgan hour-hand, a train betweensaid- 'arborand sleeve, 9. large ratchet-wheel on prising a pendent torsional rod provided with energizing said magnet, and a pendulum coma contact-arm, a sprin'gclip attached to said said spring-clip and provided with adjustable a horizontal bar sup wrtcd said spring-clip lwtwcon .--aid 'clipand stops; the weights being more sensitive to thcchangcs of temperature than the bar, whereby 'thc expansion-or conling mechanism therefor, an. elcctromagnct a contact-arm, a springclipattached to said wilibll'hc'combination of a clock-train, a drivactuating-said mechanism, electric means for wow of metals having different cxpansibilitics wherebv the pendulum automaticnllyadjusts itselftoidilfcrent temperatures.

15. The combination of aclock'train, a driving mechanism therefor, an electromagnet for actuating said mechanism, electric means for energizing said magnet, and a pendulum coma contact-arm, a spring-clip attached to said rod, :1 horizontal coupling-bar supported by said spring-clip, and weights adjustable on said coupling-bar between said clip and steps.

16. The combination of a clock-train, a drivprising-a pendent torsional rod provided with rod, 8. horizontal coupling-bar supported by said spring-clip, and provided with adjustble stops'at its opposite ends, and weights adjustable on said coupling-bar between said clip and-stops.

18. The combination ofa clock-train, a driving mechanism therefor, an electromagnet for actuating said mechanism, electric means for energizing said magnet, and a ndulum comprising a pendent torsional provided-with.

rod, a horizontal coupling-bar supported by stops, and weights adjustable on said couplingr between said clip and stops, the weights being more sensitive to changes of temperature than the bar, whereby the expansion or contraction of the bar is oflset bythe contraction or expansion of the weights, the expansion of the bar tending to separate the weights and the expansion of the weights causing them to approach each other and the contraction of each havingthe opposite effects rcsmctively.

ing mechanism therefor, an clectromagnct for energizing said magnet, and a pendulum comprisiug'a pendent torsionalrod provided with a contact-arm, a spring-clip attached thereto,

and provided with stops at its opposite ends, and weights ad ustable on said coupling-liar -ing in said bracket, aminixte-hand on said.

traction of the bar issoiisct by the contraction or expansion of the weights, the expansion of the bar tending to surparnte the weights and the expansion of the weights causing them to the energizing-circuit to eliminate residual magnetism, mechanical means a pendulum provided with an electric contact, two contactsbelonging respectively to said circuits and engaged by said pendulum for closing either circuit, and automatic means adapted to ihstantly break either circuit after each movement ofthearmature.

21'.- In an electric clock, the combination a back plate, a bracket secured thereto, an electromagnet supp rted on said bracket, an armature hingcd'to said bracket'a'nd provided at its long end with contact studs and with a pawl, a spring connected to'the short end thereof, a central arbor, a ratchet-wheel attached to said arbor and engaged by said pawl, a torsional pendulum provided with a I contact-arm engaged by said contact-studs of the armature in the oscillation thereof, and electric circuits connected with said studs.

22. In an electric clock, the combination of aneleetromagnet, an armature provided with a conductive plate, and with a conductive spring disposed adjacent to said plate and normally in contact therewith,; a fixed contact with for I swinging said armature out of contact with said magnet,

which said contact-spring engages on the movement of the armature in one direction, and electric connections forming alternate circuitspassing through said spring and plate rcspcctively.

23. In an electric clock, the combination of a back plate, a'dial-plate, a recessed bracket scoured to said back plate, a central arbor extendingthrough said plates and having a beararbor in front of the dial-plate, an hour-hand sleeve surrounding said arbor, a train connecting said sleeve with said arbor, a ratchetwheel disposed on said arbor back of said back plate, an clcctromagnct supported on said bracket, an armature hinged to said bracket adjacent to said clectromagnct, a pawl on said armature engaging said ratchetewheel, a pendulum engaged by said armature, and electric circuits controlled by said pendulum.

24. in an electric clock, the combination of a clock-train, a torsional pendulum, clectro:- magnetic means for propelling the clock-train and, maintaining mot-ions of said pendulum, the circuits-of said electromagnetic means hemovement of said pendulum and opened independently of said pendulum.

25. The combination of a clock-train, a d riving mechanism therefor, an electromagnet for actuating and mechanism, electric means for energizing said magnet, and a pendulum controlling said electric means and. comprising a pendent torsional rodprovided with a, contactarm, and means mounted on said driving mechanism and engaging said contact-arm for actuating said pendulum.

26. The combination of a clock-train, a torsionnl pendulum, an clectromagnet, an armature for said magnet provided with means connecting divectly with said clock-train for ac tuating it, and also provided with means for engaging said torsional pendulum for imparting impulses thereto, and an electric circuit controlled by said pendulum for energizing said magnet.

GEORGE S. TIFFANY.

Witnesses:

ISAAC O. HORTON, THOMAS A. CONNOLLY.

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