A wave steepness (H/L) probability curve was plotted for all data given 
under the local wind wave group and it was ascertained that about 70 percent 
of the waves theoretically could not exist as the wave steepness exceeded 
1/7 (0.14)- In some cases, the steepness ran as high as 0.4 (Figure 2). 
(The length, L was caleulated on the basis of the observed period, T). As 
wave periods were obtained from the total number of waves passing the 
observer in a given time interval, it is thought that the exceedingly high 
steepness ratios obtained may be attributed to the use of too many waves 
associated with the smaller heights in determining the average period of the 
waves of measured height. A breakdown of wave periods for this local wind 
wave group shows that a total of 68 percent of all the waves had a period 
of 2 seconds or less (Figure 3). This is manifestly a small period for an 
ocean wavee 
Inasmuch as the observed wave period was determined by measuring with 
a stopwatch the time interval between two consecutive wave crests passing 
a floating object, it might be assumed that the time measurement was made 
not between crests of similar period waves in the group but rather between 
crests of dissimilar period waves in the group. For example, a wave spectrum 
under observation might include waves of 7— and 5-second periods and the 
observer might measure the time interval between the 7- and 5-second wave 
crests rather than between two consecutive 7-Second wave crests, thereby 
getting a much smaller period than the actual one. Illustrative of this, 
Figure 4 shows a possible wave train consisting of 7- and 5-second period 
waves. "A' represents the crest of the 7-second wave and "BY the crest of 
the 5-second wave; it is quite conceivable that in measuring period the 
time interval between crest "A" and crest "B" was taken rather than the 
time required for consecutive crests "A" and "A" to pass a given objecte 
= 7 Sec., Primary Wave —-—---=5 Sec., Secondary Wove 
FIG. 4 
