I 



ON A NEW ASTRONOMICAL CLOCK. 391 



further than hitherto, and adjusting it to gain only 

 about T1 ^j- per cent, on the pendulum ; and then I 

 shall probably arrange that each pallet of the es- 

 capement be touched only once a minute. The only 

 other point of detail which I need mention at present 

 is that the pallets have been, in all my trials, 

 attached to the bottom of the pendulum, projecting 

 below it, in order that satisfactory action with a 

 very small arc of vibration (not more on each side 

 than yi^ of the radius, or I centimetre, for the 

 seconds' pendulum) may be secured. 



My trials were rendered practically abortive 

 from 1865 until a few months ago by the difficulty 

 of obtaining a satisfactory governor for the uniform 

 motion of the escapement-shaft ; this difficulty is 

 quite overcome in the pendulum governor, which 

 I now proceed to describe. 



Imagine a pendulum with single-tooth escape- 

 ment mounted on a long collar loose on the 

 escapement-shaft just as described above the 

 shaft, however, being vertical in this case. A 

 square-threaded screw is cut on the upper quarter 

 of the length of the shaft, this being the part of 

 it on which the collar works, and a pin fixed to the 



