xviii DESCRIPTION OF PLATES. 



PLATE XVI. 



Fig. 200. A fusee with an auxiliary spring, for continuing the motion when the 

 watch is wound up. The action of the main spring turns the fusee in the direction 

 A B ; the fusee acts on the ratchet wheel A B C by means of the click B, and this 

 wheel impels the toothed wheel D E by the spring C B A, which is supposed to be 

 seen through it. When the 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 maintain the motion. P. 148. 



Fig. 201. The scape wheel A B, moving in the direction A C B, impels the pal- 

 lets D,E of the crutch or anchor, alternately in contrary directions. P. 149. 



Fig. 202. A is the scape wheel, B and C the pallets of the common watch scape- 

 ment. P. 149. 



Fig. 203. The dead beat scapement. The teeth are first received on the flat or 

 rather cylindrical surfaces A, B, on which they rest until the pendulum arrives near 

 the middle of its vibration, when the teeth begin to act on the inclined surfaces 

 terminating the pallets. P. 150. 



Fig. 204. The horizontal scapement, for a watch. The tooth A rests first on the 

 external surface of the cylinder, B C, and then impels it by its inclined face, in the 

 direction B C ; it afterwards falls on the concave surface D E, and lastly impels the 

 cylinder in the contrary direction. P. 150. 



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

 and the tooth which rests on it, are supposed to be seen, the point of the tooth being 

 about to escape from the notch towards C. The short tooth D next impels 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 the notch, which causes a slight recoil in the wheel, and 

 passes by, the tooth F being beyond the r^ach 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. 150. 



Fig. 206. Mr. Mudge's watch scapement. A, the scape wheel, and one of the 

 subsidiary springs, seen 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 a liberty, by striking against the arm E ; this arm is 

 then carried on by the balance, to the end of its vibration, and impels it in its return, 

 until the pallet meets the next tooth. The other spring acts alternately in the same 

 manner, but in a contrary direction. P. 151. 



Fig. 207. An improvement on Mr. Cumming's scapement for a clock. The 

 tooth A is seen resting on a flat surface at the end of the pallet B : it is disengaged 

 by the descent of the opposite pallet into the position in which it is represented, the 

 pallet B being impelled by it at C. This pallet continues resting on the flat end of 

 the tooth, until the pin D of the pendulum 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 opposite 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, H, may be adjusted at pleasure. P. 151. 



Fig. 208. Mr. Arnold's watch scapement. The pin A, projecting from the verge 

 or axis of the balance, moving towards B, carries before it the spring B, and with it 

 the stifFer spring C, so as to set at liberty the tooth D, which rests on a pallet pro- 

 jecting from the spring. The angle E of the principal pallet has then just passed the 

 tooth F, and is impelled 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 forcing back the spring B. 

 The screw H serves to adjust the position of the detent, which presses against it. 

 P. 151. 



Fig. 209. Mr. Earnshaw'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 H the 

 adjusting screw. P. 151. 



Fig. 210. A gridiron pendulum, consisting of three bars of iron, and two of a 

 mixture of zinc and silver. P. 154. 



Fig. 211. A compensation balance, as employed by Arnold. The outside of the 



