WATCH. 



SalaiiLe, 'DlA.L-Work, EsCAPEMENT, PoWER, Maintaining, 

 and Remontoir, v/e have anticipated the coniidf ration of the 

 moft material parts of a watch, and have ^ven fuch a detailed 

 account of mo'* of the varieties that occur in the practical 

 conftnidion of thi? machine, that little remains to be done 

 in this place, but to defcnbe an ordinary watch, without re- 

 ference to its hillory, fcientific principles, compcnfations, or 

 fuperior workmanlhip ; all which have been amply dif- 

 cuflcd, and ili ' conftituent parts explained by accurate en- 

 gravings of the corrcfponding mechanifm. We may, how- 

 ever, comprt^-hend in this article the appendages which have 

 been applies', t > or aftuated by the common watch, for the 

 purpofe of either amufement or utility in civil fociety, fuch 

 as chimes, alarums, ftriking-work, and repeating meclianifm, 

 molt of whivli operate as a drag upon the works, and are 

 therefore nev r introduced in chronometers, and feldom in 

 watches of t'l • moll perfeft conftrutlion. 



Fig. I. Plate XLIV. of Horology, reprefents the in- 

 terior works of an ordinary watch with the crown-wheel 

 efcapement, as they remain on the pillar-plate when the 

 upper plate of the frame, (hewn hy Jig. 5, is unpinned and 

 removed ; and^^. 2, which is a feftion of the whole frame 

 and of its cont>-nts, fliews the conneftion of all the parts, as 

 though the calliper were in one right line. Theft; two 

 figures, by having the fame letters of reference, mutually 

 explain each other. The main-fprnig, which aftuatcs all 

 the wheels and pinions that are called in one general term 

 the movement, is contained in the circular box a, feen in 

 different views in the feparate figures 1, 2, and 8, in the laft: 

 of which its parts are given in their detached ftate, viz. the 

 box ; the relaxed fpriiig immediately above, lying in a fpiral 

 form ; the arbor with its pin, on which the interior end of 

 the fpring is hooked ; and the lid through which the pivot 

 of the arbor penetrates : this fpring is forced into the box 

 by a tool on purpofe, when it is ftrong, and then the ex- 

 terior end is hooked to a pin in the circular edge of the 

 box, fo that if the box is made to turn round while the 

 arbor is held fall, the fpring begins to coil at the centre, 

 and is thereby wound clofe round the arbor, and is by this 

 aftion faid to be luound up. The fame cffeft would be pro- 

 duced if the box were held fail, and the arbor only were 

 turned ; but in the latter cafe the chain, which requires to 

 be uncoiled from the fpring-box as this fpring is wound up, 

 would remain unmoved ; it is necelfary therefore that the 

 box be turned while the arbor is at rell, which is thus 

 efFedled : one end of the chain is made fall to the fide of the 

 fpring-box, and the other to the fufee b, after being coiled 

 feveral times round the circumference of the box ; then as 

 the fquare end of the fpring-box arbor is held by the fmall 

 ratchet and click c, feen on the reverfed face of the pillar- 

 plate in fig. 7, fo that it cannot revolve, it is obvious that 

 infertii.g a key on the fquare, of the fufee-arbor, and turning 

 it in a proper direftion, will wind the chain upon the fpiral- 

 groove of the fufee, while it is unwound from the box ; and 

 during this operation the fpring will be coiled up to the 

 centre of the box, or be put into its Hate of greateft tenfion 

 for pulling the fiilec back again. The rapid motion which 

 the fufee would have in a retrograde direction, when pulled 

 by the whole force of the coiled fpring, is prevented by the 

 train of wheel-work and balance thus ; the great wheel d is 

 not fall to the thick end of the fufee, as appears in the 

 drawings, but carries a click and click-fjjring 2, as feen in 

 Jig. 3, while the ratchet-wheel, feen in Jig. 4, is made fall to 

 the fufee ; the confequence of which contrivance is, that 

 while a key applied to the fufee-arbor winds up the watch 

 and fills the fufce-groove with the chain, until the guard 

 driven by it catchej the beak at the fmall end of the fufee ; 



9 



the click injig. 3. Hides over the iloping teeth of the ratchet 

 mfg.4, without afting on them, and thus leaves the great 

 wheel d at rcfl, in connection with the pinion e, on the centre 

 or minute-wheel arbor ; but when the fpring atts on the 

 fufee in a contrary direction, the click attached to the great 

 wheel is laid hold of by the teeth of the ratchet, which thus 

 makes it fail to the end of the fufee, fo long as the chain is 

 unwinding from the fufee ; or, in other words, til! the fpring 

 wants winding up again, which happens ufually once in 

 28 or 30 hours ; but it is commonly wound up once in every 

 24 hours, more or lefs. The a£tion of the great wheel d on 

 the pinion e, is that of a long lever driving a fhort one ; or 

 this wheel may be faid to aft under a mechanical difadvan- 

 tage, where an increafe of velocity, but a lofs of power, is 

 experienced by the pinion ; again, on the fame central arbor 

 of this pinion e is riveted the centre-wheel/, which revolves 

 in an exaft hour, as we (hall fee prefently, and this wheel 

 drives the pinion g, on the arbor of the third wheel /i, alfo 

 with a mechanical difadvantage, for the force it imparts to 

 the pinion i, on the arbor of the contrate-whecl, is again 

 diminifhed in the ratio of the diameter of the wheel to that 

 of its pinion ; thus, the force of the main-fpring is conti- 

 nually diminiihing, as it is tranfmitted through the train, 

 and when the contrate-wheel comes to be aftuated, it has 

 jnit force enough to drive the horizontal pinion on the 

 balance-wheel /, fo that the alternate impulfes given by its 

 teeth to the pallets of the balance-verge are jult fufficient 

 to perpetuate the ofcillations to the right and left, under all 

 the obllacles of friftion, dirt, wear, and the air's refillance. 

 It is a curious faft that this crown-wheel efcapement, 

 though the olde/l that we know of, is dill the molt in ufe in 

 common watchea, probably from the facility with which it 

 is conllrufted ; for certainly it is more under the influence 

 of the irregularities of the main-fpring's force than any other 

 efcapement. The properties and action of thii efcapement 

 have been minutely explained under No. I. of the article 

 Escapement, with reference to^5-. 6. P/,j/<r XX XI. of //</ro- 

 logy, to which explanation and figure therefore we requett 

 our reader's attention. 



In order that the force applied to the pallets of the verge 

 at each ofcillation may not fenfibly vary, it was found 

 necelfary to equalize, as much as polfible, the variable forces 

 of the main-fpring in its different dates of tenfion ; and the 

 moll pradlicable way of doing this has been found to con- 

 vert the cylinder on the arbor of the great wheel, which 

 would have been proper for a gravitating body, ufed as a 

 maintaining power, into a figure of a parabolic form, that is, 

 into a folid, generated by tlie revolution of a parabola, in 

 order tlrat, as the force of the fpring becomes greater by 

 increafed tenfion, its aftion on the great wheel might be 

 leffened in a fimilar proportion, by a gradual decreafe of the 

 radius of the fufee, round wliich the chain is wound, to im- 

 part the force thus modified. Every feparate fpring, there- 

 fore, has not f)nly its average force proportioned to the 

 balance it is dellined to aftuatc, when diminiflied by tranf- 

 milTion through a given train, but requires its Jalc of vary- 

 ing forces to be nicely counterafted in every degree of ten- 

 fion by ihvjhnpc of the fufee ; and this is done by means of 

 a tool, called a fufee ad'iulling-tool, which is nothing more 

 than a lever with a fiiding weight attached to the fquared 

 end of the fufee-arbor, as reprcfented mfig- 10. 7V(7/cXXl. 

 oi Horology ; for when the weight on the lever is an exadt 

 counterpoife to the force of the main-fpring in every part of 

 the fuccelTivc revolutions of the fufee, as the fpring is wound 

 up by the lever inlKad of a key, then the fiiape of the fufee 

 is proper, but not otherwife. Hence, whenever a new main- 

 fpring is put into a watch, the fufee ought to be adjulled in 



the 



