5 5 6 iWh vince’s Invejtigctthn of the 
has been before proved, the uniform motion of the cen- 
ter of gravity in a right line, remain unaltered, after 
the commencement of the motion. 
PROP. V. 
In the time the bodies make one revolution , the center oj 
gravity will move over a fpace equal to the circumfer- 
ence of a circle whofe radius is cg (Jig. i .) 
From the laft Proportion, the angular velocity of the 
lever is continued uniform ; hence the time of a revo- 
lution is juft the fame as if the point c were fixed, and 
the bodies were to continue to revolve about that point 
as a center, in which cafe the center of gravity g, in 
the time of a revolution, would evidently defcribe the 
circumference of a circle whofe radius is gc. This 
therefore is the fpace the center of gravity defcribes in 
a right line when the bodies move freely, for from the 
Iaft Propofition that center is carried uniformly forward 
with the fame velocity. 
Cor . i . Hence if the magnitude of the force acting 
at d vary, the velocity of the center of gravity will 
vary in the fame ratio as the angular velocity. 
Cor. i. Hence the point d may be found, where a 
force being applied, the bodies fhall make one revolu- 
tion, 
