New Detached Pendulum Escapement. 307 



The detent turns upon an axis at K, so that the pressure of 

 the impeller upon the pin L elevates the detent, and allows the 

 detaining tooth H to pass forwards. 



Just at this moment the second lifting pin G is entangled be- 

 tween the sides of the notch in the extremity of the spring E F ; 

 the motion of the wheel, therefore, again elevates the impeller, 

 the rise of which allows the detent to descend upon the stop N 

 and await the arrival of the second detaining tooth I, whose ar- 

 rest is announced by a distinct beat. 



The whole of the escapement has now assumed a position ex- 

 actly analogous to that which it had at first, and awaits the ap- 

 proach of the pendulum, to solicit anew its maintaining power. 



During the whole of this action the pendulum is never con- 

 nected with the train of wheels. The only body which acts 

 upon it is the impeller, and this communicates to it the impulse 

 which is generated by a descent of a constant weight through a 

 determinate distance. The lightness of the parts renders oil 

 either on the axis B or on the pin F unnecessary, so that this 

 . action is entirely freed from any error which might have arisen 

 from changes in the adhesiveness of oil. In order to solicit the 

 impulsion, the pendulum has to raise the impeller through a dis- 

 tance determined by the thickness of the pin F, and has to over- 

 come the friction of the spring against that pin. But the dia- 

 meter of the pin is so small, and the flexure of the spring so 

 slight, that the errors caused by them must be exceedingly small, 

 especially when we consider that they are not liable to any va- 

 riation. The unlocking of the detent H, instead of being per- 

 formed by the pendulum, is effected by the impeller; so that, 

 however variable may be the maintaining force, provided it is 

 never so small as to be unable to raise the impeller, nor so great 

 as to prevent the unlocking of the detent, the going of the clock 

 can never be in the slightest degree affected. 



When the pendulum rod reaches the friclion-roller, it is mov- 

 ing with a very small velocity, since it is almost at the limit of 

 its oscillation, so that nothing analogous to the blow of the com- 

 mon 'scapements takes place ; and even the sudden removal of 

 the pressure of the impeller, when the arm reaches the pin L, 

 can hardly excite any tremour in the pendulum. 



