88 TRANSACTIONS OF THE [JaN. 30 



That the speed of the propagation of the free, soHtary wave 

 in water, was the definite speed at which a horse could draw a 

 canal boat more easily than at any other speed whatever, be it 

 less or greater, because it agitated the water less. 



With these considerations noted, I pass to a brief reference to 

 the results of actual experiments. 



I found that the possible variation of the flat figure in a 

 boomerang within certain limits, was practically inexhaustible. 

 The limit at which boomerang action was the least noticeable 

 was the flat circular disc. 



In a general way it was most apparent in the shape in which 

 much the greater part of its outline of figure oscillated from 

 one side to the other of its centre of gyration, while even a 

 flat, rectilinear figure developed a well-marked effort to return. 

 My best results were with the cycloidal missile, which had an 

 area of from 12 to 15 square inches to the ounce in weight, 

 used with a throwing arm whose radius was 14 inches, in which 

 the biceps muscle was represented by a spring tension of about 

 25 pounds. Under these conditions the straight return was 

 repeatedly accomplished. But if the spring tension was 

 carried to a point largely in excess of the amount noted for the 

 same boomerang, the outward flight was one of great swiftness 

 and precision ; but the subsequent result was truly astonishing. 

 After reaching its outward limit, and after starting well back 

 upon its return, it swept suddenly round again in the direction 

 of its rotation, and started forward upon a second onward 

 flight, like our late comet, waltzing from one vortex to another. 

 Finally it retui-ned in a wide circle to the left. 



Before passing to a conclusion, possibly some further explana- 

 tory considerations of the foregoing facts and experiments . 

 may not be without interest. 



First, as to original defects : 



Quintillian has said : " Everything which art has brought to 

 perfection had its origin in nature." And while in the case of 

 the boomerang its origin may have been in nature, I believe it 

 was not one of intent, but of accident. And the reason why 

 the obscure defects, with which accident endowed it at its birth 

 grew to be actually regarded as essential qualities, I believe 

 was simply because neither art nor science had devised any 

 mechanical or crucial tests to take the place of the variable and 

 unreliable hand throwing. The effect of a slight change in the 

 impulse is greatly exaggerated in the flight ; and as no man can 

 be quite sure of throwing a missile twice alike by his arm alone,, 

 the effect of inherent faults could not easily escape detection. 



Second, as to experiments with various forms : 



