BOOMERANGS. 



of taking the course A D F E, it might fly 

 out to C in the actual direction in which it 

 was thrown, and, coming back in much the 

 same line, fall at the feet of the thrower. Or, if 

 still more strongly spun, it would actually rise 

 above this line, and travel by way of A G H, 

 falling behind the thrower himself. 



The boomerang can do more surprising 

 things still, describing circles, ellipses, and 

 more complicated figures. 



To understand how these variations may 

 arise, we must remember that the boomerang 

 is not impressed with a spinning motion only, 

 but with a very energetic forward motion as 

 well. We will suppose the forward motion 

 of the boomerang in Fig. 15 to be actually 

 forward from the reader, that is, into the page, 

 and the spin to be as described before that 

 is, the end B going forward into the page, 

 and the end A coming towards the reader. 



Then it is clear that whichever end is at 

 the right for the time being will cut the air 

 forward much more swiftly and forcibly than 

 the end which is at the left. For the right- 

 hand end has the forward motion of the whole 

 weapon increased by the forward motion of 

 the spin, whereas the left-hand end has the 

 forward movement of the whole weapon 

 diminished by the backward movement of 

 the spin. 



Now the oblique under-surface on the right 



57 



