WATCH. 



cutive are left. The pinion C fits by a long fquare hole on 

 the arbor of the great wheel of the running train, pro- 

 longed through the pillar-plate, which arbor is pivotted 

 into the upper plate, and the cock, b, which is fcrewed to 

 the pillar-plate. The hour ratchet, of fifteen teeth, is fitted 

 to this pinion C, by means of a focket, attached to and form- 

 ing part thereof; and the upper ratchet, of four teeth, is at- 

 tached by a hole through its centre, in a finiilar manner to 

 the under ratchet ; and the two are firmly held together, and 

 alfo to the pinion, by means of two fcrews which pafs through 

 them both, and are tapped into the pinion, as reprefented 

 in feftion in Jig. 4 ; confequently, whatever portion of a 

 circle the pinion is made to revolve by the aftion of the 

 rack, the two ratchet-wheels neceflarily do the fame. It 

 may not be amifs to notice in this place, that the arbor of 

 the great wheel pafles through the barrel which contains 

 the repeating main-fpring ; and that the barrel is fcrewed 

 to the under fide of the pillar-plate, and is conneAed with it 

 exaftly in the fame manner as in the cafe of the common re- 

 peating motion, and its operation is the fame ; but the bar- 

 rel arbor is not pivotted between the upper and pillar- 

 plates, as in the cafe of the common motion, but into the 

 upper plate and the cock b, fcrewed to the pillar -plate ; 

 and the connection between both the hammers and the mo- 

 tion is entirely above the pillar-plate, through the medium 

 of the hammer-tails, as will be explained. 



The pieces next to be defcribed are the two hammers, and 

 their conneftion with the motion. The two pivots or centres 

 of motion of the hammers are generally placed at equal dif- 

 tances from the arbor that carries the pinion C, and perpendi- 

 cular to the plates, and, confequently, parallel to that arbor, 

 and to one another ; they are pivotted into the frame, and their 

 upper pivots are prolonged through the pillar-plate, to receive 

 the hammer-tails, L and-M : there is a pin planted in each 

 hammer, at a (hort diltance from its centre of motion, which 

 alfo pafles through the pillar-plate, in which there are 

 notches or flits forming portions of circles concentric with 

 the centres of motion of the hammers, for thefe two pins to 

 pafs through, as feen in Jig. 3 ; it is by means of thefe 

 pins 4 and 5,7?^^. 1 and 2, which pafs into notches, made on 

 purpofe to receive them, in the hammer-tails L, M, that 

 thefe tails, when aAed upon by the two ratchets, in 

 tjieir tuni aft upon the hammers ; were it not for this con- 

 trivance, the hammer-tails, when impelled by the ratchets, 

 would turn on the pivots of the hammers, as their cen- 

 trea of motion, without raifing the hammers. The ham- 

 mers are kept to their places by the two hammer-fprings 

 •u and *, which prefs againft the pins 4 and 5, that pafs 

 tlirough the hammers, below the hammer-tails, and as clofe 

 to the furface of the pillar-plate as they can be, to be free 

 from the furface of the plate : it is by thefe fpnngs that 

 the hammers, railed by the aftion of the ratchet-wheels, 

 are impelled forward to ftrike ; and the ftronger they are, 

 provided they are not too ftrong for the power of the 

 main-fpring, the louder will be the blow (truck. Imme- 

 diately connefted with the hammers are the hammer-tails 

 L, Mi through the agency of which the hammers are raifed 

 to ftrike, by means of the two ratchets N and O ; thefe tails 

 require to be extremely well fitted on the upper pivots of 

 the hammers, prolonged through the pillar-plate, which are 

 their centres of motion, though not fo tight but that they 

 will move with eafe up and down on thofe pivots ; for on this 

 aftion depends the whole performance of the motion : the 

 part of the hammer-tail, which, by way of diftinftion, is 

 called the afting lever or pallet, is that againft which 

 the teeth of the ratchets aft to raife the hammers, the 

 upper ratchet being the fmaller of the two ; the lever of 



9 



the quarter hanimer-tail is left as much longer than the 

 lever of the other hammer-tail, as is neceffary for it to 

 reach the ratchet. To prevent the hammer-tails, when afted 

 upon by the ratchets, from turning on their centres of mo- 

 tion, there is, as has been noticed in defcribing the ham- 

 mers, a notch in each hammer-tail, to receive a pin planted 

 in each hammer, parallel to its centre of motion, and which 

 pin for this purpofe is made to pafs through a circular notch 

 in the pillar-plate. 



The next piece to be defcribed is the crofs-piece, or piece 

 K. The furface of this piece, when at reft, is in a plane 

 parallel to the pillar-plate, and the piece moves upon two 

 pivots, which aft in holes in the two fmall cocks c and d, 

 fcrewed, the cock c to the foal of the cock b, and the 

 cock d to the pillar -plate Y Z. This piece K is maintained 

 in its place, when the motion is at reft, by the end of the 

 httle all-or-nothing piece I, which prefles againft its arm 8, 

 on the one fide of its centre of motion, and by the fpring q, 

 ^7h^ch prefling againft the under fide of its arm 9, on the 

 other fide of its centre of motion, caufes it to bear againft the 

 little all-or-nothing piece I ; the hammer-tail L is main- 

 tained in its place, depreffed, or raifed on its centre of mo- 

 tion folely hy the aftion of this piece K ; the hammer-tail M 

 is alfo depreffed in the fame manner, but is raifed on its cen- 

 tre of motion by the fpring u, the end of which is made to 

 bear on the under fide of the hammer-tail for that purpofe ; 

 and by the power of this fpring it is impelled upwards, and 

 made to follow the piece K, when it is raifed by the little 

 all-or-nothing piece I, as before defcribed. 



The ufe of the piece K, when the unlocking takes place, 

 is to dcprefs the hammer-tails on their centres of motion, (the 

 prolonged upper pivots of the hammers) to bring them into 

 the fame planes as the hour and quarter ratchets N and O, 

 they being, when the motion is at reft, fituated confiderably 

 above thofe planes ; and as foon as the ilriking is finillied, to 

 raife up again the hammer-tail L, and by relieving the other 

 tail M from its preffure, fuffer it to be raifed by its fpring u. 

 For this purpofe the arm 7 enters into a groove, made on 

 purpofe to receive it in the hammer-tail L, and the arm 

 6 is made to bear upon the top of the other hammer -tail 

 M. The aftion of the piece I will be more fully explained 

 prefently. 



The pieces next to be defcribed are the large all-or-no- 

 thing piece H, and the little all-or-nothing piece I. The 

 upper furface of the piece H is in the fame plane, and it 

 is of the fame thicknefs with the piece D, by which it is 

 afted upon : the upper furface of the piece I is on the fame 

 plane with the upper furface of the quarter-rack, and as 

 thick as it can be for its underfide to be perfeftly free from 

 the fprings -u and p on the pillar-plate : it is neceffarily re- 

 quired to be of a certain thicknefs, being afted upon by 

 the two pieces E and H. Both the all-or-nothing pieces 

 move on ftuds, fcrewed into the pillar-plate, which thus 

 become their centres of motion, the piece H on the ftud r, 

 the piece I on the ftud i: it is indifpenfable that thefe 

 ftuds ftiould be perpendicular to the face of the pillar-plate, 

 and the pieces perfeftly well fitted upon them : it is more- 

 over ablolutely neceffary that both the all-or-nothing pieces 

 ftiould, in all fituations, be parallel to the plane of the 

 pillar-plate ; on which account, the piece H, being a thin 

 piece, is fixed to a focket, the hole through which focket 

 is perfeftly well fitted to the ftud, and the ftud is left as high 

 as it can be, to avoid touching the underfide of the dial. 

 The unlocking is effefted by the aftion of the piece D 

 on the piece H, in the following manner : when the pen- 

 dant is puftied in to make the watch repeat, the arm/of 

 the piece D comes into contaft with the hour-fnail, and 



caufes 



