according to (la), (2a), (3a), (4a) 



X^ = 107 m A2 = 307 m A3 = 163 m 

 T, = 8,3 sec T2 - 14.0 sec T^ = 10.2 sec 

 (T, = 12.95 m/sec (T2 = 21.9 m/sec (Xo - 16. m/sec 

 a^L ~ 3»0 m ®2 ~ ^*^ ^ *3 ~ ^'^ ™ 



Fig. 7 shows the resultant wave patterns at a wind velocity of 

 16 m/sec. The upper wave train (a) represents this theoretically 

 constructed "wave record" at a locality x = for a time interval 

 of 260 sec. The lower wave tra;Ln (b) represents a "wave record" during 

 the same time at a locality x = 550 m, which means about I/3 nautical 

 miles away from the locality of "wave record" (a) in the direction 

 of wave propagation. These theoretically constructed "wave records" 

 indicate that groups of large waves are to be expected only inter- 

 mittently at a certain locality . At x = in our example they 

 occur at the beginning, at x = 550 m at the end of the "wave record." 

 The groups follow with a time interval of about 45 sec between each 

 group. Within these groups some waves are growing up to considerable 

 height. But in nature these waves presumably do not attain their 

 exact theoretical height. When approaching a certain maximal steep- 

 ness which depends upon the wind velocity, they become xinstable and 

 the crests break over. Because of a certain regularity in the occur- 

 rence of these outsize waves in groups it is to be expected that there 

 is a certain regularity in the occurrence of high breakers too . 



When a "family" of distinct groups has passed the locality of 

 observation, the sea surface patterns gradually change their char- 

 acteristic appearance. By and by the distinct groups disappear and 



28 



