1893. ] NEW YORK ACADEMY OF SCIENCES 85 
It is no longer that the boomerang must have equations for a 
peculiar curve ; it is not that its points of excellence are so 
slight that Europeans can scarcely see them ; it is not that its 
top rounded side brings it under Newton’s proposition 34 ; it is 
not that it must have a screw-shape twist; it is not that an 
element of back pressure unveils the mystery ; but the secret 
of its magic power is now found to reside in a great multitude 
of little ‘‘ dents’’ chipped from its surface. 
And so the magnifying of inherent faults or imperfections 
into qualities of the greatest importance, culminates in this 
curious way, while in fact, as I believe, these ‘‘dents” are hut 
the evidences of rude and primitive knife cuts—possibly scooped 
out by a sea shell or an opossum’s tooth, for want of better 
tools, and are of esthetic or duthropological rather than of 
‘mathematical interest ; with no further import than the much 
prized hammer marks in antique brass. 
It is these varying and contradictory theories that constitute 
for the most part what I have already termed the somewhat 
astonishing literature of the boomerang. Ihave reviewed them 
because it is necessary to rid our minds of their influence. Not 
that I have the presumption to intimate, even remotely, that a 
good physicist needs to have this pointed out to him by me, 
but principally because good physicists have evidently never 
attemped a solution of the difficulties, and so have, possibly, by 
their mere inattention, permitted thoroughly competent matbe- 
matical skill and effort to be wasted upon a misapprehended 
basis of fact, reported by presumbly competent authority. 
Few people, comparatively, have ever seen a boomerang, and 
fewer still have ever studied it, or seen it thrown. What, then, 
could be more misleading than to liken the motions of a boom- 
erang to the sweep of the oblique of a wind-mill?. or worse 
still, to say that it goes through the air somewhat as a screw 
propeller goes through the water? 
The screw of a propeller rotates edgewise, but the progress 
of the screw is bodily, along with the ship, ‘‘ broad set to the 
door,”’ so to speak. The two motions are in different planes, at 
right angles with each other, whereas both motions of the 
boomerang are edgewise, in the same general plane and direc- 
tion, and cannot be compared to the progress of a screw 
propeller in water, except to utterly mislead the mind. 
Comparatively few writers on the subject have taken the 
pains to go beyond the matter of shape, and look into the 
element of artificially applied force and motion, for the true 
solution of its action. 
A paper published in the ‘‘Journal of the Royal United 
