Belas — On the Structure of Water- Jets. 209 



A musical note differs from a noise in having its vibrations 

 periodic, and the smoother the curve that represents the wave- 

 motion, the fuller and purer is the note. So it is with these jets 

 of water. The more troubled and ruffled they appear to the eye, 

 the more confused and irregular are the streams of drops that com- 

 pose them ; while their symmetry and elegance of outline are 

 but outward indications of order and regularity of formation. 



[Explanation op Plates. 



