The experimental data presented in this study were taken from 

 two sources. The data presented in Table 1 were taken in the steel 

 wave tank of the Beach Erosion Board. This tank is 96 feet long, 

 If feet wide and 2 feet deep. The other source of data is a report 

 by MORISON (U) who made similar measurements in a tank 60 feet long, 

 1 foot wide and '3 feet deep at the University of California Fluid 

 Mechanics Laboratory. The data shown in Table 2 were taken from 

 Morison's report with the exception of the values for Cpj q and Crp 

 which were computed from the wave characteristics as given by Morison. 

 It should be noted that the wave lengths used in the computation of 

 the theoretical velocities for the Beach Erosion Board data were com- 

 puted from the measured water depth and wave period, (T) using the 

 Airy theory, while the wave lengths used in the computation of the 

 theoretical velocities for the University of California data were com- 

 puted from the measured wave velocity (Cm) and the measured wave period. 



The measured velocities (Cm) shown in Table 1 were obtained by 

 placing two parallel-wire gages (5) 10 feet apart in the wave tank and 

 recording the w ave profile from these gages on a dual-channel Brush 

 recorder. A timing device made four marks per second on the record of 

 the wave profiles. Thus, knowing the distance between the gages and 

 the time required for the wave to travel from one gage to the next, 

 the average wave velocity between the gages was determined. 



Since there was considerable variation between the measured and 

 theoretical velocities, a statistical comparison was made which con- 

 sisted of finding the correlation coefficient 6) for each set of 

 theoretical values and the measured values. The correlation coefficients 

 were found for the Beach Erosion Board data independently, the Morison 

 data independently, and for the combination of the two. The results 

 of this comparison are shown in Table 3. 



TABLE 3 





Correlation C< 



oefficients 





Correlation 



For 



For 



For 



Between 



BEB Data 



Morison Data 



Combination 



c m vs C H - 



.95 



.97 



.96 



C m VS Cm 



.91 



.98 



.95 



C m vs C T ' .95 .97 .96 



From the correlation coefficients shown, it can be seen that 

 theory neglecting wave steepness (eq. l) predicts the wave velocities 

 very well, since a correlation coefficient of 1.00 represents perfect 

 correlation. When effect of wave steepness is included in the theory 

 (eq. 2), the correlation coefficient for the Beach Erosion Board data 

 decreases and the correlation coefficient for the University of 

 California data increases, indicating poorer and better, respectively, 



