92 



0.43 



220 



1.02 



341 

 1.58 



Figure 17. Response of a bed form to a reduction in a (the mid-third 

 of test section in experiment 48) . Here N = 26, following 

 experiment 47 where N = 52. Upper and lower numbers by each 

 photo give N and (D/a)n, where n is the number of cycles 

 since the beginning of the experiment. 



50 



