635

MANUFACTURES.

^ture^" Watc ^ w hich has remained with the same escapement' and nearly in the same shape as when first invented.

of

oseription

Plate lxiii., fig - . 1 and 2, is the plan and elevation of thecom- works of a common watch, the position of the different;watch, parts in the elevation being a little deviated from that inj,! - lxiii. which they would be seen in viewing the watch, in' s ' h 2 > 3. order that their action may be more clearly understood,but the position and manner of arrangement will bereadily perceived from the plan. The moving power isa spiral steel spring which is coiled up close, by a toolused for the purpose, and put into a brass box called thebarrel; the spring has a hook at its outer end which isput through a hole in the side of the barrel and rivetted,and the inner end has an oblong opening cut through itto receive a hook upon the barrel arbor. This arborextends through the bottom of the barrel, and is madesquare to hold a worm or tooth wheel d, which isturned round by a worm and serves to adjust the actionof the spring to that of the fusee; the end of the arborprojects beyond this and is attached by a pivot into thelower or face plate A of the watch ; the top of the barrelhas a cover put over it, through which the pivot of thearbor projects and works in a socket in the upper plate D.

The barrel thus mounted has a steel chain a,hooked to the upper part and coiled round, the otherend of which is attached to the fusee E. It is thusevident that when the fusee is turned by the watch keyd will wind the chain off the barrel on itself; and, as°ne end of the spring is fastened to the barrel and theother end to the arbor, (which is prevented from turninghy the worm wheel beneath,) the spring will be coiledU P in a smaller compass than it was before, and by itsReaction will, when the watch key is taken off, act on thetusee and exert a force to turn the movements of thew atch. The fusee has a spiral groove cut round it intvhich the chain lies; this groove is cut by an engine inSl, ch a manner that the chain shall pull from thest *iallest part of the fusee when the spring is wound up,an d acts with its greatest force, and gradually increasesln size as the spring unwinds and acts with less power,®o that the motive power of the watch may be alwayse same. For the action to be always equal, thek e ngth of the spring, at any state of unwinding, shouldinversely in proportion to the radius or diameter ofe fusee, which is the lever by which it acts. This ise cted by adjusting the position of the spring withP e et to the fusee by the worm b, which turns up thespnng and causes j t to act w ;(^ greater force. By thisjustinent the power of the spring at the commence-fion\ ariC * com P^ et ' on its action, being made in propor-thp 1 h° ^' e res P ect ‘ ve diameters of the fusee upon whichfrom ^ ’ Sco ‘' e< *’ the intermediate states of the spring,ex tj - e P art icuiar curve given to the fusee, will beon ^ ln t ' le con 'ect proportion, and an equable action

^Mhe works produced.

which 6 ^ USee ^ as a ratchet wheel at the lower endwheel en ? a ^ es a click fixed in a hollow cut in the greatU P thp 6 f ln or< ^ er *^ at when the watch is being woundWhen b US6 n ma y. sp P round without the wheel, but thatc °ntra 6 act ' on of the spring, it is turned in thethe wdiL it; en S a S es this wheel, and thus puts

forty- ' h ° l ” e watc h in motion. The great wheel hasand tu Sht teeth on its circumference, which engagewith Hi™ a plIuon of ei S'ht teeth fixed on the same axleen ffao 6 ce ntre wheel g, which has filty-four teeth, and

wfteeT h . a T U1,0n 0l ~ six ieaves °n the axle of the third: this wheel has forty-eight teeth and turns

a pinion of six teeth on the axle of the contrate wheel i, Mechanical

which has forty-eight teeth cut parallel to its axle by Processes.

which it turns a pinion of six leaves fixed to the balance

wheel k. The pivots of the axle of this wheel turn one

in a frame F, called the potance, fixed to the upper

plate, and the other in a small piece called the counter

potance, so that when the two plates are put together

the balance wheel pinion may work in the teeth of the

contrate wheel. The balance wheel has fifteen teeth

by which it impels the balance l , the axle of which,

called the verge, has two pallets projecting from it nearly

at right angles to each other; these are acted upon by

the balance wheel, as shown enlarged in fig. 4, where the Pig. 4.

lower pallet is supposed to be in contact with one of the

teeth of the balance wheel, which as it turns pushes the

pallet round and the balance with it, till the balance has

made about a quarter of a turn, the tooth of the balance

then slips off and escapes. In this position the watch

would run down if it were not for the upper pallet at

that instant engaging another tooth on the opposite side

of the balance wheel, which, as it moves in a contraiy

direction, pushes the balance back again till the tooth

escapes the pallet, the lower pallet then engages the

wheel as before, and thus the action is continued ; m is

the pendulous spring which is made of steel and of a

spiral figure; the inner end of it is fixed to the verge just

beneath the balance, and the outer end pinned to a stud

fixed to the top of the upper plate of the watch, so that

the balance will rest only in one position, and if it is

moved either way by the balance wheel the spring-

will have a tendency to bring it to the same position

again. When the lower pallet, for instance, has just

liberated a tooth of the balance wheel, the pendulous

spring is strained and returns the balance to its point

of rest instantly, the balance wheel following the upper

pallet by the action of the main spring; the balance

will, of course, by the momentum which it has received,

vibrate past its natural point of rest, but this is, by the

assistance or force of the main spring upon the pallet,

made to vibrate sufficiently in the other direction to

permit the tooth to pass.

It is evident that, by lengthening or shortening thisspring, the velocity of the balance will be regulated;this is done by a contrivance shown in fig. 5. con- Fig. 5.sisting of a plate of brass screwed to the top of theupper plate ; at one place it is hollowed out to receive awheel n of twenty teeth, which turns a segment of awheel p called the curb ; this moves round in a cir-cular groove, which has a projecting leaf q with a notchin it to receive the pendulous spring, so that by turningthe wheel with a key put on the square part of the axle,the spring is lengthened or shortened so as to give adifferent power and make the balance vibrate quicker orslower: the axle of the wheel has a hand upon it whichworks round upon a graduated dial, so that when therate is altered it may serve as a guide to set it by. Theupper pivot of the verge runs in a cock screwed to theupper plate, which covers the balance and protects itfrom violence, and the lower pivot works in the bottomof the potance; the socket of the pivot of the balanceis made in a small piece of brass which slides ina groove made in the potance, so that by drawino- theslide in or out the teeth of the balance wheel shal? justclear one pallet before it engages another.

The watch is so adjusted by the sprimr that thebalance shall vibrate so as to turn the centre wheelround once in an hour, the spindle of which projects