Chap. 3. PHILOSOPHY.

117

Chap. III.

Of CENTRIPETAL FORCES.

W E have just been describing in die preceding chapterthe effects produced on a body in motion, from itsbeing continually acted upon by a power always equal instrength, and operating in parallel directions a . But bodiesmay be acted upon by powers, which in different places shallhave different degrees of force, and whose several directionsshall be variously inclined to each other. The most sim-ple of these in respect to direction is, when the power ispointed constantly to one center. This is truly the cafe ofthat power, whose effects we described in the foregoing chap-ter; though the center of that power is so far removed, thatthe subject then before us is most conveniently to be consider-ed in the light, wherein we have placed it: But Sir IsaacNewton has considered very particularly this other cafe ofpowers, which are constantly directed to the lame center. Itis upon this foundation, that all his discoveries in the systemof the world are raised. And therefore, as this subject bearsso very great a share in the philosophy, of which I am dis-coursing, I think it proper in this place to take a short view.of some of the general effects of these powers, before wecome to apply them particularly to the system of the. world.

* § 85, & c .

x. These