90 TRANSACTIONS OF THE [Jan. 30 
investigators, referred to by 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, illustrated by 
Scott Russell’s discovery for the medium of water, I quote from 
Prof, 8. P. Langley, of the Smithsonian Institution, who makes 
the entirely new proposition in a recent publication, entitled 
‘‘ixperiments 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 experiments. 
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 hopeless 
mystery, 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 pursuit 
I have developed certain refinements of configuration, which. 
are most beautifully 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 reached a stage to warrant their disclosure, 
