Wooden-ball bearing and the turning of pinions
Eight wooden balls held in a race to move a weight, and how pinions reverse a wheel's motion
The upper right shows a ball bearing: eight wooden balls (a b c d e f g h) used in place of rollers to move a weight, kept in order by eight pivoted wheels (i K l m n o p q) that perform the office of turning without letting the balls escape, the parts labelled around a circle. A companion note on the disc marked 'semicircle' states that all pinions driven by the teeth of one and the same wheel turn contrary to that wheel, and that pinions touching one semicircle of the driving wheel turn opposite to those touched by the other semicircle. A T-handled worm (auger) screw is drawn at lower right.
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Ball race of eight wooden balls to move a weight
The balls a b c d e f g h are of wood, used in place of rollers to move a weight, while i K l m n o p q are pivoted wheels that keep the balls in order, do the office of turning, and prevent them escaping.
Pinions turn contrary to the wheel that drives them
All pinions turned by the teeth of one and the same wheel turn in the contrary motion to that wheel. Moreover, pinions touching one semicircle of the driving wheel turn opposite to those turned by the other semicircle.