near station 40 and the minimum near station 25 (a depression in what 
would be a higher antinode without the transverse wave). 
The transverse wave developed almost immediately during each run, as 
indicated by the stationary recordings made at station 40 at the beginning 
of the run from 65 to 70 hours (Fig. 7). This figure also demonstrates 
that the transverse wave was not a cross wave since a cross wave would 
have caused a varying wave height on either side of the tank at the 
same station. 
As part of the automated procedure for determining Kp, a running 
mean wave height was determined for each wave crest along the tank (pro- 
cedure described in Vol. I). This running mean was subtracted from the 
wave height to smooth any longer period oscillations from the envelope 
recording. However, these running mean data were also a means of deter- 
mining the amplitude of the transverse wave, since the transverse wave 
along any range appeared to be a longer wavelength modulation. 
The effect of the transverse wave is clearly shown in plots (Fig. 8) 
generated by the program WVHTCN for the wave recordings in Figure 6. 
The lighter line indicates the wave height variation along the tank; the 
heavier line indicates the running mean (average of wave heights within 
a wavelength of each individual wave). The variation of the running 
mean is essentially a plot of the transverse wave along each range. The 
maximum and minimum values of the running mean were measured and averaged 
for the four recordings on each wave envelope analyzed by the automated 
method. Table 7 gives the average amplitude of the transverse wave for 
each wave record. The maximum amplitude of 0/077 foot (2.35 centimeters ) 
occurred at 50 hours and the minimum amplitude of 0.038 foot (1.16 centi- 
meters) at 140 hours. With one exception, the height of the transverse 
wave was greater than 0.062 foot (1.89 centimeters) before 90 hours and 
less than 0.060 foot (1.83 centimeters) after 90 hours. This decrease 
coincides with the increase in Kp in this tank after 90 hours. 
The transverse wave maximum and minimum peaks traveled down the tank 
in roughly the path shown in Figure 9. The wavelengths over the profile 
would have been shorter, probably as indicated. The wave height at any 
point (e.g., station 40, range 9) did not vary significantly over a 
period of a few minutes (Fig. 7). 
In the fixed-bed (control) tank, the waves were observed to break 
unevenly across the tank. This indicates that a transverse wave was also 
generated in this tank, but the only wave data were recorded along the 
centerline of the tank, which would not have shown any evidence of the 
transverse wave. 
d. Cross Waves. Cross waves occurred for a brief time over a section 
of the movable-bed profile in experiment 72B-06, but were not measured. 
The effect, if any, was not apparent in the profile data. 
24 
