MECHANICAL PARADOXES. 



It is made of a flat thin piece of hard wood 

 (see Fig. 13), which has fairly pointed ends 

 and fairly sharp edges, and a bent or crescentic 

 outline as seen upon the flat, though as viewed 

 towards the edge it is in one plane. The figure 

 shows a common shape, seen from above ; and 

 below it is a view of the thin edge. The angle, 

 as seen in the upper view, is very unsettled, 

 and is often determined in detail by the 

 direction of the grain of the wood. 



FIG. 13. ORDINARY SHAPE OF BOOMERANG. 



The two blades, or limbs, are not always 

 exactly in one plane, but often have a slight 

 twist in their set, so that while the front edge 

 of one limb looks slightly upwards, that of 

 the other will look a little downwards. 



The performance of this weapon depends 

 entirely upon the manner in which it is used. 

 In its flatness it resembles a leaf, a piece of 

 card, a sheet of tin, or a bird's wing ; and so 

 far as its flatness is concerned, it might be 

 expected to behave like any of these. Now, 



4 8 



