1 66 



THE POPULAR SCIENCE MONTHLY. 



The connections thus traced, parallel to connections already traced, 

 are at once seen to be natural on remembering that militant activities, 

 intrinsically coercive, neccessitate command and obedience, and that 

 therefore, where they predominate, signs of submission are insisted 

 upon ; while, conversely, industrial activities, whether exemplified in 

 the relations of employer and employed or of buyer and seller, being 

 carried on under agreement, are intrinsically non-coercive, and there- 

 fore, where they predominate, only fulfillment of contract is insisted 

 upon : whence results decreasing use of the signs of submission. 



^- 



WATER-WAVES AND SOUND-WAVES. 1 



By J. NOEMAN LOCKYEE, F. E. S. 



LET us find a piece of tranquil water and drop a stone into it. 

 What happens ? a most beautiful thing, full of the most precious 

 teachings. The place where the stone fell in is immediately surrounded 

 by what we all recognize as a wave of water traveling outward^ and 



Fig. 1. Superposition of Two Wave-Systems. 



then another is generated, and then another, until at length an exqui- 

 site series of concentric waves is seen, all apparently traveling outward 



1 From advance sheets of " Studies in Spectrum Analysis " ("International Scientific 

 Series," No. XXIII.). 



