the given range of wind velocity. In a later report ("Instructions 

 for practical wave forecasting") certain "standard types" of period 

 distributions will be presented for practical use, covering the 

 wind velocities up to 24 m/sec. 



The results of all measurements are summarized in figure 5j 

 taking the periods of maximum frequencies out of each individual 

 series and plotting them as a function of wind velocity. This dia- 

 gram shows the range of characteristic periods between wind velocities 

 of 2 m/sec and 20 m/sec. At low wind velocities of about 4 m/sec we 

 find a scattering of observed periods at fully developed sea between 

 1 and 4 seconds, at moderate wind of about 10 m/sec between 4 and 

 10 seconds, and at strong wind of about 16 m/sec between 7 and 15 

 seconds. 



In most cases the lowest characteristic period T, appeared 

 clearly separated from the highest period Tp, but very often second- 

 ary maxima were indicated in the frequency distribution between two 

 limiting periods, as shown in figures 1 to 3. These different per- 

 iods, indicated by peaks in the diagrams of the different observational 

 series, are marked in figure 5 by dots, circles and crosses. At low 

 wind velocities the intermediate period T^ seems to approach the 

 period Tp* whereas at higher wind speeds it seems to approach T,. 

 At winds lower than 4 m/sec the occurrence of higher periods was 

 less striking and at light winds less than 3 m/sec no observations 

 of characteristic periods higher than T-, are made. But in all cases 

 the observed periods scattered over a certain interval, as is generally 

 to be expected in interference patterns (see section 3)* 



The results of observations represented in figure 5 indicate 



17 



