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of particles, revolving at the didance 0 A of the- 
demoted point A, as n is to unity. 
It is well known, that the centripetal force,, where- 
by any body is made to revolve in the circumference 
of a circle, is fuch, as is fufficient to generate all the 
motion in the body, in a time equal to that , wherein 
the body defcribes an arch of the circumference, 
equal in length to the radius. Therefore, if we here 
take the arch AR = OA, and affume m to exprefs 
the time, in which that arch would be uniformly 
defcribed by the point A, the motion of a particle 
of matter at A (whofe central force is reprefented 
by f) will be equal to that ) which might be uniformly 
generated by the force J\ in the time m and the mo- 
tion of as many particles (revolving, all, at the fame 
didance) as are expreffed by cn (which, by hypothe- 
cs, is equal to the momentum of the whole body), 
will, confequently, be equal to the momentum, that 
might be generated by the force J\cn, in the fame 
time m. Whence it appears, that the momentum of 
the whole body about its axe P p is in proportion to 
the momentum generated in a given particle of time 
m\ by the given force F in the direction AL, as 
nc f't'try is to Fy,m'. or, as unity to -X — (be- 
J y ncf m v 
caufe the quantities of motion produced by unequal 
forces, in unequal times, are in the ratio of the forces 
and of the times, conjundlly). Let, therefore, AL be 
taken in proportion to A M, as 
F 
ncf 
III • • 
X — is to unity 
(fuppofing AM to be a tangent to the circle A BCD 
in A), and let the parallelogram AMNL be com- 
pleated j drawing alfo the diagonal AN- ; then, by 
the 
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