﻿Dr. J. R. Wilton on Ripples. 699 



The two corresponding sets o£ values of x and y are given 

 in Tables IV. a and IV. 6, and the ripples* are shown in 

 tigs. 4 a and 4 b, respectively. 



Table IV. 

 Ripple of length 2*44 cm. 



z. 



CZ? — X. 



y- 











•025 



7T/6 



•21 



•050 



tt/3 



•37 



•087 



tt/2 



•52 



•038 



2tt/3 



•71 



-•039 



5tt/6 



•96 



-•086 



7T 



1-22 



-•095 



Fig. 4 a. 



Bipple of length 2-44 cm. ; amplitude -182 cm. ; velocity 24 - 6 cm./sec. 



Fig-. 4 b. 



Eipple of length. 2*44 cm. ; amplitude -175 cm. ; velocity 22-2 cm./sec. 



It is possible that the dimple at the crest of the second 

 ripple is due only to the neglect of terms of higher order ; 

 but it seems very unlikely that the form of the first ripple 

 can be due to this cause. One is tempted to say that ±a is 

 probably unstable, 4 /> probably stable. In any case there is 

 room for experimental investigation of the forms of ripples 

 of this particular length, and also of the form of "high*' 

 ripples of very short "wave-length, such as that shown in 

 no-. 1. It would also be interesting to obtain experimentally 

 the forms of the ripples whose lengths are given by «=] ;», 

 * = l/4, &c. 



* I have not strictly adhered to the customary distinction between 



ripples and waves. 



