BOOMERANGS. 521 



when thrown ag'ainst a wind.. Those which are bent through a hirge 

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

 manufacture or by subsecpient warping-") 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 be 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; but the first two specimens that he con- 

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



