773 



PLATE XVI. 



Fiff. 200, A fusee n ith an auxiliary spring, for con- 

 tinuing the motion wlica the watcli is wound up. The 

 action of the main sprii-g turns the fusee in tlie direc- 

 tion A B; tlie ftisee nets on the ratchet wheel ABC 

 by means of tlic click B, and this wheel impels the 

 toothed wlieel D E by the spring C B A, which is sup- 

 posed to be seen through it. When tlie watch is 

 ■wound up, this spring forces back the wheel ABC 

 against the click F, which serves as a fixed point, while 

 the other end continues to act on D E, and to main- 

 tain the motion. P. 193. 



Fig. 201. The scape wheel A B, moving in the 



direction AC B, impels the pallets \), E of llie crutch 



or anchor, alternately in contrary directions. 1'. 191. 



Fig. 202. A is the scape wheel, B and C the pallets 



of the common watch scapement. P. 194. 



Fig. 203. The dead beat scapement. 'J'he teelh 

 are first received on the flat or rather cylindrical sni-- 

 faces A,B, on which they rest until the pendulum ar- 

 rives near the middle of its vibration, when the teeth 

 begin to act on the inclined surfaces terminating the 

 pallets. P. 195. 



Fig. 201. The horizontal scapement, for a watch. 

 The tooth A rests first on the external surface of the 

 cylinder, BC, and then impels it by its inclined face, 

 in the direction BC; it afterwards falls on the con- 

 cave surface D K, and lastly impels the cylinder in the 

 contrary direction. P. 195. 



Fig. 205. The duplex scapement. A B is the pallet, 

 through which the cylinder, and the tooth which rests 

 ou it, arc supposed to be seen, the point of the tooth 

 being about to escape from the notch towards C. The 

 short tooth D next nnpels the point of the pallet, and 

 the long tooth E falls on the cylinder. It first rests on 

 the convex surface, and then drops into tlie notch, 

 which causes a shght recoil in the wheel, and passes by, 

 the tooth F being beyond the reach of the pallet; but 

 on its return, the tooth falls again into the notch; and 

 when it escapes, the pallet is impelled as before. P. 

 196. 



Fig. 200. Mr. Mudge's watch srai)cmcnt. A, the 

 scapewheel, and one of the subsidiary springs, seciV 

 from above; B a general view of the balance, with 

 both the subsidiary springs, seen from one side. The 

 point of one of the teeth rests at C on the end of the 

 pallet, which is bent so as to detain it until the pin D, 

 which is attached to the balance, sets it at liberty, bv 

 striking against the arm E: this arm is then carried 

 on by the balance, to the end of its vibration, and im- 

 pels it in its return, until the pall«;t meets the next 

 tooth. The other spring acts alternately in the same 

 tuunner, but in a couiriiry diicctioa. P. 19T, 



Fig. 207. An improvement on Mr. Cumming's 

 scapement for a clock. The tooth A is seen resting 

 on a Hat surface at tlie end of the pallet B ; it is dis? 

 engaged by the descent of the opposite pallet into the 

 position in which it is represented, tlie pallet B being 

 impelled by it at C. This pallet continues resting on 

 the flat end of the tooth, until the pin U of the pendu- 

 lum strikes against the arm E, which is carried before 

 it, and impels the pendulum in its descent, until the 

 pallet B acquires the situation in which the opposita 

 pallet is represented, and sets that pallet at liberty 

 from the tooth E, which has raised it. The situation 

 and magnitude of the weights G, II, may be adjusted 

 at pleasure P. 197. 



Fig. 208. Mr. Arnold's watch scapement. The 

 pill A, projecting from the verge or axis of the balance, 

 moving towards B, carries beiore it the spring B, and 

 with it the stifler spring C, so as to set at liberty the 

 tooth D, which rests on n pallet projecting frotri the 

 spring. The angle E of tlie principal pallet has then 

 just passed the tooth F, and is impelleil by it until the 

 tooth G arrives at the detent. In the return of the 

 balance, the pin A passes easily by the detent, by forc- 

 ing back the spring B. The screw II serves to adjust 

 the position of the detent, which presses asjaiiist it. P. 

 197." 



Fig. 209. Mr. Eariishaw's scapement. A is the 

 unlocking pallet, B the spring on which it acts, C the 

 detent, holding the tooth D by a pin; E is the point 

 of the principal pallet first impelled by the tooth F, 

 G is the tooth next locked, and U the adjusting screw. 

 P. 197. ■ ■' ^ 



Fig. 210. A gridiron pendulum, consisting of three 

 bars of iron, and two ot a mixture of zinc and silver. 

 P. 200. 



Fig. 211. A compensation balance, as employed ty 

 Arnold. The outside of the hoops A, B is of Irass, 

 the inside of sleeh the weights C, D are screwed 

 backwards and forwards, in order to obtain the reqiii- 

 siie degree of coiiipeiisutiun. I'he weights E, F, arc em- 

 ployed to regulate the mean rate of the watcli, and 

 G, U, and I, for adjusting it to all positions with re- 

 spect to the hori/on. P. 201. 



Fig. 212. The compound plate A B rests on two 

 supports, which are adjusted to a proper distance by 

 luriihig the double screw C, the flexure of the plate 

 by heat raising the bar D, which supports the pendu- 

 lum, while its effective length is determined by a 

 fixed clip, whicfi is seen below the plate. P. 211. 



VOL. r. 



D 



