90 TRANSACTIONS OF THE [J AN. 30 



investigators, referred to bj' various writers as the "nutation 

 of its axis." You observe this form returns directly to my feet. 



Referring again to the matter of definite speed, ilkastrated by 

 Scott Russell's discovery for the medium of water, I quote from 

 Prof. S. P. Langley, of the Smithsonian Institution, who makes 

 the entirely new proposition in a recent publication, entitled 

 "Experiments in Aerodynamics," viz.: 



That for a body moving in air ' ' the more rapid the motion is, 

 the less will be the power required to support and advance it 

 up to some remote limit not yet attained by experiment." In 

 this connection I venture the belief that this limit of speed has 

 been attained for the boomerang in my exjDeriments. 



I have not the time to quote various authorities concerning 

 one particularly remarkable phenomenom of the boomerang 

 flight. So far as I can find, no explanation has been offered 

 for it. I refer to what is usually called its reverse curve. For 

 instance, all observers agree that the invariable result of a 

 right handed throw is a more or less circular orbit — to the left, 

 in the direction of its rotation. But at the end of its return 

 course it makes a reverse curve— opposite to the direction of its 

 rotation — the return flight tracing an imaginary letter S. I 

 have never found a hint of its solution in the plentiful theories 

 existing, and its cause seemed a most tantalizing and hoj^eless 

 m}' stery, until the requirement of a definite speed dawned upon 

 me. Then it was clear. 



The acceleration of its return speed, under the law of falling 

 bodies, is sufficient to reach the definite speed required to make 

 the boomerang soar. That is, its advancing edge is again lifted 

 by the wind of advance as it nears the earth. Its right-handed 

 throw gives it an inclination which it will retain throughout its 

 course, and so it again veers to the left. But as its course is 

 now reversed from the direction of its outward flight, of course 

 its curve is reversed. 



One object of my experimentation was to attain an ideal 

 boomerang flight ; that is to say, one in which the two motions 

 could be so nicely adjusted, that its return flight should termi- 

 nate just at the moment it second soaring speed should be 

 attained, thus avoiding the reverse curve, adapting it in short 

 target practice, wherein the target is behind the shooter. 



Another object was in a different direction, and in its ^Jursuit 

 I have developed certain refinements of configuration, which 

 are most beautifullj' adapted to illustrate certain other principles 

 involved, exceedingly interesting in their nature, but as my 

 time is about up, and as their application to a possible useful 

 purpose has not yet reache'd a stage to warrant their disclosure, 



