34 



SCIENTIFIC RECREATIONS. 



Another simple experiment may prove amusing. Into a piece 01 wood 

 insert the points of two knives, and at the centre of the end of the bar insert 



Fig. 28 Another experiment. 



a needle between the knife handles. The wood and the knives may then be 

 balanced on another needle fixed in a cork at A. 



We may conclude this chapter by summing up in a few words what 

 the Centre of Gravity is. We can define it as " that point in a body upon 

 which the body, acted on solely by the force of gravity, will balance itself 

 in all positions." Such a point exists in every body, and equally in a 

 number of bodies fastened tightly together. The Centre of Gravity has -by 

 some writers been denominated the Centre of Parallel Forces, or the Centre of 

 Magnitude, but the Centre of Gravity is the most usual and best understood 

 term. 



