MAINTAINING POWER OF A CLOCK. 



way the parts b a and g h will be gradually lengthened as the 

 weight P descends at the expense of the parts c d and / e, which 

 will be shortened to an equal extent, so Fig. 23. 



that the weight p will be raised through 

 the same space as that through which the 

 weight P is lowered. During this process 

 the wheel D is kept in constant revolution, 

 and the first wheel of the train of clock- 

 work being fixed on its axle, a motion is 

 imparted by it through that train to the 

 hands. 



"When it is desired to wind up the clock, 

 the hand is applied to the cord c d, which 

 is drawn downwards, so that the fixed 

 pulley revolves, the catch E dropping from 

 tooth to tooth until the weight P has been 

 raised to the highest, and the weight p has 

 fallen to the lowest point. The parts g h 

 and f e of the cord not being at all affected 

 by this, the pulley D continues to turn as 

 before by the effect of the preponderance 

 of p, which acts as powerfully while it 

 ascends as it did when it descended. 



It appears, therefore, that, by this ar- 

 rangement, the motion of the works and of 

 the hands is not suspended during the pro- 

 cess of winding up. 



45. If the works of a watch be impelled 

 by the force of a mainspring without a fusee, in the manner 

 represented in fig. 17, it is evident that the movement must be 

 suspended during the process of winding up, because the ratchet- 

 wheel B, by which the force of the spring is transmitted to the 

 works, is then relieved from the action of the catch n o. This 

 defect may, however, in such case be removed by a very simple 

 expedient. Instead of connecting the external extremity of the 

 mainspring with a fixed point, let it be attached to the inside of a 

 barrel surrounding it, and let the wheel c be attached to this 

 barrel. In that case, when the axle of the ratchet-wheel is 

 turned in winding up, and the ratchet-wheel, therefore, relieved 

 from the action of the catch, the wheel c will be acted upon by 

 the barrel, which will itself be impelled by the reaction of the 

 external extremity of the spring which is attached to it, the 

 winding up being effected only by the internal extremity. 



This is the arrangement generally adopted in chimney and table 

 time-pieces, as constructed in France and Switzerland, and also in 



41 



