The Laics of Motion. 



point, bears, in fact, the weight of the whole 

 body ; and while it is supported the body cannot 

 fall, because all its parts are in perfect equilibrium 

 about that point. Thus, if I endeavour to balance 

 my cane, by laying it across upon my finger, 

 after some time I find a place where neither 

 end will preponderate. The part, then, which 

 rests upon my finger is the centre of gravity. An 

 imaginary line drawn from the centre of gravity 

 of any body towards the centre of the earth, is 

 called the line of 'direction , and it is in this line 

 all heavy bodies will descend. 



The difficulty of sustaining a tall body upon a 

 narrow foundation will be evident, if you attempt 

 to balance your cane with its small end upon 

 your finger. Its centre of gravity is somewhere 

 about the middle of the cane, and unless you 

 have sufficient dexterity to keep the foundation 

 on your finger perpendicular under the centre of 

 gravity, it will undoubtedly fall. In this consists 

 the great difficulty of posture-masters and rope- 

 dancers. The dancer on the rope balances him- 

 self by a long pole loaded at both ends with 

 lead, and keeps his eye steadily on some point 

 exactly in the line of the rope, by which he can 

 see whether his centre of gravity is either on one 

 side or the other of his slippery foundation, and 

 if any irregularity takes place he rectifies it by 

 his balancing pole. 



Every body stands firm on its base, when the 



