3 88 POPULAR LECTURES AND ADDRESSES. 



But the inaccuracies hitherto tolerated in astron- 

 omical clocks may be clue more to the faultincss 

 of the mercury compensation pendulum, and of 

 the mode in which it is hung, and of the instability 

 of the supporting clock-case or framework, than to 

 imperfection of the escapement and the greatness 

 of the arc of vibration which it requires ; therefore 

 it would be wrong to expect confidently much 

 improvement in the time-keeping merely from im- 

 provement of the escapement. I have therefore 

 endeavoured, though perhaps not successfully, to 

 improve both the compensation for change of 

 temperature in the pendulum, and the mode of its 

 support, in a clock which I have recently made 

 with an escapement on a new principle, in which 

 the simplicity of the dead-beat escapement of 

 Graham is retained, while its great defect, the 

 stopping of the whole train of wheels by pressure 

 of a tooth upon a surface moving with the pendulum, 

 is remedied. 



Imagine the escapement-wheel of a common 

 dead-beat clock to be mounted on a collar fillim; 

 easily upon a shaft, instead of being rigidly attached 



