CENTRE OF GRAVITY. 



51 



Fig. 20. 



lower figure on the preceding en- 

 graving, until it makes half a revo- 

 lution and reaches the place of the 

 upper figure, when it will remain 

 stationary. If a curved body, as 

 shown in Fig. 19, be loaded heav- 

 ily at its ends, it will rest on the 

 stand, and present a singular ap- 

 pearance by not falling, the cen- 

 tre of gravity lying between the 

 I singuiarhj haianccd by two hcavy portlous ou the end of 

 the stand. A light stick of some 

 length may be made to stand 

 on the end of the finger, by 

 sticking in two penknives, so 

 as to bring the centre of grav- 

 ity as low as the finger-end 

 {Fig. 20). 



If any body, of whatever 

 shape, be suspended by a hook 

 or loop at its top, it wiU neces- 

 sarily hang so that the centre 

 of gravity shall be directly un- 

 der the hook. In tliis way the 

 centre in any substance, no 

 matter how irregular its shape 

 may be, is ascertained. Suppose, for 

 instance, we have the irregular plate 

 or board shown in the annexed figure 

 {Fig. 21) : first hang it by the hook 

 «, and the centre of gravity will be 

 somewhere in the dotted line a b. 



Centre of gravity maintained by two 

 penknives. 



