806 Description of Mr Witherspoon's 



vented from advancing by the opposition of the detent to the 

 detaining tooth H. The end of the spring E F is furcated, the 

 pin resting in the bottom of the notch, and keeping the spring 

 bent upwards from its nataral position by a distance rather more 

 than the minute diameter of the pin. 



The oscillation of the pendulum is so nearly completed, that, 

 when finished, the impeller B C D E may be hfted till the ex- 

 tremity of the spring just escapes from the pin F, and takes up 

 a position a little to the left of its present one. The whole weight 

 of the impeller now rests upon the pendulum ; but when the 

 pendulum begins to retire, the extremity of the spring is not ar- 

 rested by the pin F, but passes close by it, directing its motion 

 towards the pin G. 



The impeller continues to press against the pendulum rod, 

 and increases its momentum until the arm B E reaches a pin at 

 L, projected from a branch of the detent H K L. After this the 

 pendulum continues its oscillation uninterrupted. 



