BESCRIPTION Ol A CLOCK ESCAPEMENT. \JJ 



thachine now sent to your address; and I will thank you 

 to lay it before the Sucietv of Arts &c. the first opportunity. 



This escapement will do for a pendulum of any length, will answer for 

 •and the friction is so sinaii, that it does not require any oil, f^ peU U * 

 for it may be made as little as the tooth of the wheel can 

 sufficiently touch the impelling spring, and yet be properly 

 scaped. 



It is necessary, that the detent spring, the impelling Requisites, 

 spring, and the pendulum should all spring from one right 

 line or centre; and that the impelling spring should be so 

 much stronger than the detent spring, us will always be suf- 

 ficient to unlock the wheel. 



The machine being wound up, and the pendulum put in Its mode of 

 motion toward the leftside, the impelling spring unlocks action ' 

 the wheel, when a tooth falls against the pallet, where it 

 remains uut ; l the pendulum returns; then moving the im- 

 pelling spring, and the wheel being free, the weight on the 

 a,xis c it to advance while it escapes one tooth off the 



end o. me pallet or spring, and another tooth is locked 

 against the detent spring, as before, while the pendulum 

 returns, and the impelling spring again unlocks the detent; 

 as the impelling spring moves towards the left, the resistance 

 it meets with by the elasticity of the detent spring in fan- 

 locking is returned to it, so that there is no more power lost 

 than what was caused by the pressure of the wheel against 

 the detent spring; by which means it is freed from the loss 

 of the maintaining power, which is evident in all detached 

 escapements I have seen, by the pendulum or crutch, &c, 

 touching a spring or lifting a lever to regain the position for 

 unlocking the wheel. 



I am, Sir, 

 Your most obedient humble servant, 



GEORGE PRIOR, Jun. 

 P. S. The screw in the pendulum rod is to adjust the 

 machine when fixed up. 



Description of Mr. Prior's Escapement, Plate V, Fig, 



1, 2. 



Fig. l is a side, and fig. 2 a back view of it, which is sup- D . . 

 posed to be taken from behind the clock; a represents the thtelcape" ° 



Vol. XXVI. July, loll). ^ axis mc,u - 



