Accordingly the depth and form of the bar can be related to wave 

 characteristics by considering the dependence of HdHs upon aol\. 



A more complete description of a bar is obtained from an examina- 

 tion of variations in the form, considering the bar profile as the form. 

 The general relation defining the bar profile is obtained as follows. 

 Any point on the profile may be determined by the parameters y and 

 2 (see fig. 1) in which y is the depth of the point with respect to the 

 undistm:bed water surface and z is the horizontal distance from a 

 vertical line passing thi'ough the crest, C, of the bar. This distance 

 will be regarded as positive if the point is shoreward of C. By dimen- 

 sional reasoning as in Equation 6, we obtain the relationship: 



7 



and again neglecting <r^, 



7 



=Kwt't'') (^) 



which is the desired general relation for the form or configuration of 

 bars. 



Section III. EQUIPMENT AND PROCEDURE 



Experiments were made in two wave tanks, one 1.5 feet wide, 2 feet 

 deep and 30 feet long; the other 14 feet wide, 4 feet deep and 85 feet 

 long. Schematic views of the small and large tanks are shown in 

 figm^e 2 A and IB, respectively. The conditions illustrated are those 

 for a beach having a slope of 1 on 70. The experimental beach for 

 each sketch is to the left of the mark 0; the section to the right of the 

 mark is a transition. In a more suitable tank this transition section 

 would not have been necessary; instead the beach slope would have 

 extended to the bottom. The distorted proportions of the approach, 

 or transition segment, restrict the normal motion of the sand toward 

 the experimental beach and thus might alter the dimensions of the 

 bar eventually formed. It is considered that the test results for the 

 1/70 slope may be affected by these conditions but those for the steeper 

 slopes are believed to be reliable. The mark of the figure is solely 

 a reference point for measuring distances and identifying stations. 

 The depth of water in front of the wave generator is variable, the 

 depth being adjusted, depending on the height of the waves, to control 

 the position of the breaking waves on the experimental beach. 



Tests in the small tank were made with beach slopes of 1 on 70, 

 1 on 30, and 1 on 15. Those slopes were established always to the 

 left of 0, with the transition segment to the right of the same for all 



