Mechanics.

hor of the Swing-Wheel. Eat if only 56 be allow’d,then it must drive a Pinion of 7, and these last Num-bers are now generally used. Thus much for the TimePart , as far as the Minutes and Seconds : As for thePinions and Wheels to strew the Hours, they are thefame as was before shewn in the Watch, Art. 26, 27.

33. In Spring Clocks the Disposition of the Wheelsin the Watch Part is such as is here represented in theFigure, where the Swing Wheel F is in an horizontalPosition, the Seconds not being strewn there by an In-dex, as is done in the large Pendulum Clocks, accord-ing to the foregoing Calculation : Whence in theseClocks the Wheels, are disposed in a different Manner,as represented in Fig. 4. where C is the Great-Wheel,D the Centre or Minutc-Wheel, both as before; butthe Contratc-Wheel E is plac’d on one Side, and Fthe Swing-Wheel is plac’d with its Centre in the fameperpendicular Line GH with the Minute-Whcel, andwith its Plane perpendicular to the Horizon, as are allthe others. Thus the Minute and Hour Hands turnon the End of the Arbor of the Minute-Wheel at a,and the Second-hand on the Arbor of the Swing-Wheelat b.

34. It remains now that we give an Account ofthe Machinery of the Striking-Part of a Clock. Hereas in the Watch-Part , the Primum Mobile is a largeSpring, in the Spring-Barrel G ; but in long Pendu-lums it is a Weight, as is well known. This by itsCord and Fusee moves the Great Wheel II; that givesMotion to the Pin-1Vheel\\ that continues it to the De-tent or Hoop-l'Vhesl K ; and that to the TVarning-WheelL; which at last is spent on the Flying-Pinion Q_,which carr es the Fly or Pan ; and by its great Veloci-ty it meets with great Resistance from the Am it strikes,and by this Means bridles the Rapidity of the Clock’sMotion, and renders it equable.

35. All these Wheels are quies.ent or motionless, un-less when at the Beginning of each Hour the Detent Ois lifted up, by which Means the Work is unlock’d,and the Whole put into Motion by Virtue of the Spring

in