steepness, but running in the same direction as the wind and even 

 as high as the steeper "tumiatuous sea." Following these longer 

 waves by eye from a look-out position on the mast, they appeared 

 to change their shape rather soon and disappeared, being replaced 

 by steeper and shorter waves. 



In figures 1 to 3, three series of observations are represented 

 as examples of frequency distributions for observed periods at nearly 

 steady wind conditions. The characteristic periods cover a more or 

 less broad interval depending on the wind velocity. At lower values 

 we find mostly a rather sharp limitation of the observed period in- 

 terval. This means that waves with periods lower than a certain 

 value have only minor significance, and do not visibly influence the 

 striking pattern of sea surface roughness. 



Figiire 1 shows a scattering of observed periods between about 

 2.5 and 8.5 seconds, and some distinct peaks in this interval. Be- 

 sides a frequency maximum between 3»0 and 4.5 seconds, maximum peak- 

 ing occurs between 5.0 and 6.5 seconds, and at 7*5 to 8.0 seconds. 

 The single observations of this series were obtained when the ship 

 drifted with stopped engines about 150 nautical miles southwest of 

 the Azores. The Y/ind was steady easterly with a velocity of 9 m/sec. 



In figure 2 are represented the observations of a series at 

 13.5 m/sec wind velocity. The periods scatter between about 4 and 13 

 seconds. Maximum peaking occurs at about 6.6, 8.7> and 11.8 seconds. 

 Similar distributions are to be found in other series. At a wind 

 velocity of I6 m/sec (figure 3) the range of periods is between 6.5 

 and 15 seconds with maximum frequencies at 8,3 seconds for the short- 

 est characteristic waves, between 10.0 and 11.5 seconds for the next 



13 



