BIPPLES 421 



of oscillation in which surface tension plays a comparatively small part, 

 while the smaller value represents the length of the wave in which surface 

 tension is the predominating factor. Such weaves are called ripples. No 

 wave or ripple can be produced by a moving object whose velocity is less 

 than this critical value of 9'2 inches per second, and a breeze of velocity 

 less than this has no power to ruffle the surface of a still pool. 



