BOOMERANGS. 



causes a greater error on the original side, 

 and so on till a real wobble is set up. A hand 

 resting lightly on the handle-bar, not consciously 

 guiding or straightening the machine, but un- 

 consciously checking each irregular movement 

 before it has had time to develop, leaves the 

 wheel free to follow its own general tendency 

 to keep straight. 



So the force of the thrower gives the boom- 

 erang a general tendency to move in a given 

 direction. The way in which its edges, of 

 slightly irregular shape, cut the air would 

 cause it to begin irregular movements which, 

 allowed to become excessive, would result in 

 movements of alternate swings or continual 

 turning over, such as we see in falling leaves 

 or slips of paper, or in thrown cards. The 

 steadying action of the gyrostatic influence due 

 to the spin, like the hand on the steering-bar 

 of a bicycle, checks such irregularities at the 

 beginning, and so leaves the boomerang free 

 to follow the course impressed upon it in the 

 throw. 



Before leaving the spin of the boomerang, 

 we must consider how its crescent shape helps 

 in producing the spin which is so essential in 

 maintaining the steadiness of its flight. 



We know that it is difficult to throw any 

 ordinary stick such as a walking-stick by 

 one end without giving it such a motion that 

 it turns end over end during its flight. 



51 



