BOOMERANGS. 521 



when thrown against a wind. Those which are bent through a large 

 enough angle and happen to be twisted (either by carelessness in 

 manufacture or by subsequent warping a ) after the manner of a right- 

 handed screw are returning boomerangs of the first type. In many 

 of these the twist is so large as to he conspicuous, and when once the 

 connection between the form and the return flight has been noticed, 

 the process of development is complete. 



"This may be illustrated by the fact that when the author first made boomerangs 

 he was only aware of the need for rounding; hut the first two specimens that he con- 

 structed happened to have right-handed twist and returned admirably. 



