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CENTRE OF GRAVITY. 



proved by reasoning which is generally intelligible ; but in all cases whatever 

 this point may be easily determined by experiment. • 



If a body uniformly dense have such a shape that a point may be found, on 

 either side of which, in all directions around it, the materials of the body are 

 similarly distributed, that point will obviously be the centre of gravity. For 

 if it be supported, the gravitation of the particles on one side drawing them 

 downward, is resisted by an effect of exactly the same kind and of equal amount 

 on the opposite side, and so the body remains balanced on the point. 



The most remarkable body of this kind is a globe, the centre of which is 

 evidently its centre of gravity. 



A figure, such as fig. 2, called an oblate spheriod, has its centre of gravity 



Fig. 2. 



at its centre, C. Such is the figure of the earth. The same may be observed 

 of the elliptical solid, fig. 3, which is called a prolate spheroid. 



Fig. 3. 



A cube, and some other regular solids, bounded by plane surfaces, have a 

 point within them, such as above described, and which is therefore their centre 

 of gravity. Such are figs. 4. and 5. 



r. 4. 



Fig. 5. 



