Pook IX. Mechanic Powers. 261of Nechanick Pomers. Giving all honour and Praiſe totat great Maſter of Arts, and Fountain of all Wiſdom , theOmnipotent God Bleſſed for evermorc.

1 had here put an end to Mechanic Povers, but meetingwith ſome new inventions relating thereto, lately publiſiit inFrance by an able Mat hematician, Which if put in practice maybe uſeful and beneficial in Engins; thought fit to add themby way of Appendix, and they are theſe that follow.

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APPEN D IX.

BOOK X.

Of Epicycloids, and their aſe in Mechanicks.

Definitions.

Eg. ITF the circle ABD be rouled or turn'd about upon the54 arch Abd of any Circle , the point D which is theextream or end of the Diameter A D, will by its mo-tion deſcribe the Line D 14, 15, 16, 17 d, which iscalled an Epicycloid.

The circle A B is called the generating circle of the Epi-cycloid.5 The arch A h d is che Baſe of che Epicycloid. N

If the generating circle roul on the out ſide of che circle ofthe Baſe, the Epicycloid is called Exterior, or Outer: But if thegenerating circle roul on che inſide of the circle, the EpicycloidIs called Interior, Or Inner. ö

The ſpace contain d by the Ef icycloid, and by its Baſe, i8 cal-

led the ſpace of the Epicycloid.The