WATCH. 



for fome few minutes after, coming into contaift with the 

 ratctet, which is fituated in the fame plane as the arm o, 

 caufes it, and alfo the fnail, to advance a fufficient quan- 

 tity to enfure tlie fafe bearing of the arm/ on the fnail, 

 and confequently the corred ftriking of the watch : this 

 cffeft, from the conllrudion of the parts as juft defcribed, 

 is produced, without didurbing either the wheel Q of 48, or 

 the wheel of communication R, and confequently without 

 moving the hands. But it yet remains to explain the mode 

 in which motion is communicated to the hour-hand : the 

 cannon-pinion of four tecth,or pins, revolving with the centre- 

 wheel once in an hour, neceflarily caufes the wheel of 48, in 

 which it afts, and with it the wheel of communication, to 

 revolve once in Vj c twelve hours ; and the wheel of com- 

 munication afting on the hour-wheel, fo called becaufe it 

 carries the hour-hand, is of the fame fize and number of 

 teeth as itfelf, and therefore caufes it and the hour-hand to 

 make one revolution in twelve hours. 



The feveral parts of the motion and their refpeftive ufes 

 being now defcribed in detail, it remains laftly that we 

 defcribe the general aftion of the whole. 



Let us fuppofe the watch made to repeat in the ufual 

 manner, by pufhing in the pendant at the three-quarters and 

 a half-quarter pafl feven o'clock, the rack A B, fg. 2. by 

 the prefTure of the pufhing-piece, is carried forward until its 

 further advance is flopped by the arm /, of the piece D, 

 reaching the feventh ftep from the exterior point of the 

 hour-fnail F ; at the fame time the rack, by its aftion on the 

 pinion C, winds up to a certain degree the main-fpring; and 

 the hour and quarter ratchets N and O, being attached to 

 this pinion, are carried forward with it, or rather, relative to 

 the ftiape of the teeth of thofe ratchets, are carried backwards 

 with it : the piece D, neceflarily advancing with the rack, 

 being immediately attached to it, difengages the quarter-rack 

 E, pi-evioufly kept in its place by the pin 3, which quarter- 

 rack being difengaged, is by the power of its fpring h im- 

 mediately brought forward after the rack A B, until it is 

 flopped by its arm y, reaching the quarter-fnail G ; but in 

 this cafe, the watch being to ftrike the three-quarters and 

 the half-quarter, the advance of the quarter-rack is almofl 

 immediately flopped by its arm y, coming agamfl the ftep, 

 the farthell removed from the centre of the quarter-fnail G : 

 the iuflant the arm/, of the piece D, has, by its preffure 

 againft the hour-fnail F,aftedfufficiently upon the large <7//-or- 

 nothing piece H, the unlocking is efFefted. By unlocking is 

 meant that portion of the total aftion of the motion, every 

 time the watch is made to repeat, which confifts in the ham- 

 mer-tails being fet at liberty to defcend into the fame planes the 

 two ratchet-wheels are in. By the aftion of the piece D, with 

 the all-or-nothing piece H, which in its turn afts on the little 

 all-or-nothing piece I, this piece I is thrown from under the 

 piece K ; and this piece K, being no longer fupported by 

 the little all-or-nothing piece I, has its two arms 6 and 7, by 

 which the fituation of the hammer-tails, on their centres of 

 motion is determined, depreffed by the aftion of the fpring q, 

 on its arm 9, until the two hammer-tails are brought into the 

 fame planes as the two ratchets N and O, and are thus placed 

 in a fituation to be aded upon by thofe ratchets, and through 

 them the hammers. The power of the blows ilruck by the 

 hammers depends on the ftrength of the hammer-fprings 

 and *; which power is communicated to the hammers, by the 

 fprings bearing againft the pins 4 and 5, planted in them, 

 which pafs through the pillar-plate into the hammer-tails : 

 ■when by the aftion of the ratchet-wheels on the hammer-tails 

 the hammers are raifed, thefe pins prefs againft the hammer- 

 fprings and continue fo to do, thus gradually increafing the 

 power of the fprings until the hammer-tail efcaping from 



the tooth of the ratchet, the hammer is by the ftrengtli of 

 the fpring fuddenly thrown forward, and made to ftrike. 

 The friftion of the running-train and of the parts of 

 the motion, added to the refiftance of the two hammer- 

 fprings, is the whole power the repeating main-fpring has 

 to overcome ; and the ftronger thefe fprings are, provided 

 they are not too ftrong for the power of the main-fpring, 

 the louder will be the blows ftruck. The number of the 

 teeth of the ratchets that are brought to aft on the ham- 

 mer-tails, is the fame as of the hour to be ftruck, which 

 are determined by the two fnails. The unloi;king being 

 thus effefted, the aft of ftriking commences ; the power 

 by which the repeating main-fpring was wound up, being 

 removed, the fpring immediately uncoils, and returns 

 into its former ftate, carrying with it the pinion C, the two 

 ratchets N and O, and the rack A B ; the hammer-tails 

 L M, having been depreffed, and from the aftion of the 

 arms 6 and 7 of the piece K upon them, continuing in the 

 fame planes with the ratch'rts, are neceffarily afted upon 

 by them, and thus is the ilriking of the hours and quar- 

 ters effefted. The inftant the ftriking is completed, the 

 rack A B continuing to return overtakes the quarter-rack 

 E, and by means of its pin 3, carries it with it : at the 

 moment the quarter-rack begins to move, one of its teeth, 

 which tooth is regulated by the quarter or half-quarter that 

 has been Ilruck, afting on the pallet of the little all-or-nothing 

 piece I, this piece is brought back to its former fituation, 

 and through it the piece K, and the hammer -tails ; and all 

 the pieces of the motion return by the power of the repeat- 

 ing main-fpring, into the fame fituations they were in before 

 the watch was made to repeat. 



The mode by which, in this conftruftion of repeating 

 work, the proper number of quarters, and the half-quarter, 

 if any, as fhewn by the hands, is ftruck, is pecuhar to 

 itfelf, and requires to be particularly explained. The 

 hour-fnail and the great ratchet are fo proportioned to one 

 another, that, as has been before obferved, according to the 

 ftep on the fnail, the arm/ of the piece D defcends upon ; 

 fo is the number of teeth of the great ratchet fent back, 

 previoufly to the unlocking taking place, to engage as foon 

 as the unlocking ftiall be effefted, in the hammer-tail of the 

 hour-hammer : thus, fuppofe the watch to repeat l-wrhf, 

 the arm/ defcends to the twelfth or loweft ftep of the 

 hour-fnail, and at the fame time the ratchets revolve a fuffi- 

 cient quantity for the twelve fuccefiive teeth, that aft on 

 the great hammer -tail, to come into aftion : it, on the con- 

 trary, the watch were required to ftrike one, the arm of 

 the rack would defcend to only the firft or exterior ftep 

 of the fnail, and the ratchet would revolve a fufficient 

 quantity for the firft only of the twelve teeth to come into 

 aftion with the hour hammer-tail. It is evident, from the 

 above defcription of the aftion of the twelve teeth of the 

 great ratchet that aft on the hour hammer-tail, that the 

 tltree teeth in the fame wheel which, conjoiptly with the 

 fmall ratchet of four teeth, are employed to ftrike the 

 quarters, muft be fo fituated relatively to the twelve teeth 

 that ftrike the hours, that when the watch is made to repeat 

 they will precede thofe teeth, in their advance towards the 

 hammer-tails ; othervvife the quarters would be repeated 

 before the hours ; for if the aftion of thefe pieces is at- 

 tended to, it will be fecn, that, in the aft of winding up 

 the repeating main-fpring, as many teeth of the two 

 ratchets will pafs under the hammer-tails, as are to aft on 

 them before the unlocking is effefted : confequently, the 

 tooth that firft paftes under the hour hammer-tail would be 

 the laft to aft upon it in returning ; and every time the 

 watch is made to repeat, the three teeth of the great 



ratchet, 



