Mechanic“ Pommer.

O F

CIRCULAR MOTION.

BOOK. VIII.

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PRO POF. I.Of mix Motion from Circular and Rigbt, or from two

or more(Arcular.

WII a Wheel is moved upon a plane ſuperficies, I ſay, theſame of a Globe, or ball, the central point only of theWheel, or Globe, is moved with right motion, all the other points,or parts of the moved Wheel, or Globe, are moved with à mixtmotion of circular and right. N

This motion of rotation on a plane hath admirable propertiesthroughout, which being rightly percieved, it will be eaſy tounderſtand the other mixt motions: Wherefore we make 2beginning from it; but yet we firſt adviſe that circular motiontruly and Phyſically conſiſts of many right lines, nevertheleſs.in this place we will conſider it even as if it were altogetherſimple motion, but where it will be needful to conſider thoſemall parts of right motion of which ciicular motion is com.pounded, there we will make particular mention.

Fig. 109. Let then the Wheel, or orb, be AZ J. ñinſiſtingon the Plane AD on which it is to be roled, or turnẽd, and let

the right line AD be equal to the arch A Q ſo that while theWhecl is moved towards D, the point Qmnay touch in thepoint D: Inthis motion tis manifeſt, Pirſt, thut the Centre of theWheel O is moved by the right line O E, for ſince the Wheel

always