182 Relation of the Laws of Mechanics to Perpetual Motion. 
the center of gravity of the whole has reached the lowest point, 
the mption will cease, except that it may continue a while, from 
~ the sagen already acquired. 
n this principle, easily perceive the defect of those 
numerous vee: wheels, which have been formed with 
Be cavities in the radii or other parts, so as to contain fluids or balls 
7 ' rolling alternately to and from the center. The object here is to 
ee have the weights near the avis, while they are ascending, and 
wy Near the periphery when descending, so as to act upon the prin- 
- ciple of the wheel and axis. The fallacy is the same here, as in 
« the longer and shorter arms of the lever. But to detect — 
id there is no necessity of examining the particular structure. What 
ever be the disposition of the parts, when the center of gravity 
of the wheel and its contents has reached the lowest point, the 
tendency to move, from the weight, is at an end. The defect of 
the contrivance is also evident from the consideration, that as the 
wheel revolves, each of the balls must rise to a certain height, 
..and it isi mmaterial by what route it arrives there, whether by 
going ae on the sertery, or eae a shorter cqurse near the 
ie te so rit a ight, as a moving force, it 
Ot ‘be e necessary to enter into a atenie consideration of the - 
F rings. The difficulty, in‘the two cases, is nearly the 
me. - spring, which is coiled up, as ina watch, produces its 
; Se wind it up requires a force eq 
th which apex 
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mach unery. : 
m , the. ahiuiinnes oft 
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ed "Saag one whe 
xpa ds. There i as therefore, no o balauicé-left, fof Pig a 
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