1893.] NEW YORK ACADEMY OF SCIENCES 85 



It is 110 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 but 

 the evidences of rude and ijrimitive knife cuts — possibly scooped 

 out by a sea shell or an opossum's tooth, for want of better 

 tools, and are of aesthetic 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. I have 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 difliculties, and so have, possibly, by 

 their mere inattention, permitted thoroughly competent mathe- 

 matical skill and effort to be wasted upon a misapprehended 

 basis of fact, rei3orted 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 artiiicially applied force and motion, for the true 

 solution of its action. 



A paper published in the "Journal of the Eoyal ruitecl 



