24 



THE APPLICATIONS OF PHYSICAL FORCES. [BOOK i. 



afterwards transmits to the system of pinions and cogged wheels 

 forming the clock mechanism. In the figure, for simplicity's sake, 

 we have omitted the intermediate wheels, p P' is the pendulum or 

 regulator of the movement. Its oscillations are transmitted to E by 

 means of the fork / and from the arbor E D to the pallet ABC, which 

 is called an anchor-pallet from its form. ABC then oscillates in the 

 same manner as the pendulum itself. And as its two extremities 

 A c are curved in such a manner as to allow them to fall between 

 the teeth of the' wheel E during the time that one of the teeth rests 

 on the upper surface of one of the extremities of the pallet, the 

 movement of the wheel is checked. At each oscillation of the pallet, 

 a tooth of the wheel thus stopped frees itself and the movement 



FIG. 5. Mechanism of the regulating pendulum. 



Fio. 6 Anchor escapement. 



continues, so that the movement, which would .be continuous if it 

 were due to the action of the weight alone, becomes periodic, the 

 duration of each period being that of one oscillation of the pendulum. 

 As the beats are isochronous, the movement of the toothed wheel is 

 also isochronous, and that of all the other wheels. But the arrange- 

 ment of the portions A and c is such (Fig. 6) that each time the tooth 

 of the wheel presses on one of them to free itself, it communicates 

 its movement to the anchor, then to the pendulum, the arc of oscil- 

 lation of the latter thus remains constant; and the oscillations are 

 stopped only when the motor, either weight or spring, ceases to act. 



