ADDENDUM 



Since the preparation of this paper and of the wave forecasting 

 manual (H.O. Pub. No. 603), two papers of interest in connection with 

 this paper have come to the attention of the author. The first paper, 

 by Arakawa and Suda (1953), gives some data on the measurement of 

 the average wave length of a wind-driven sea. The second paper, by 

 Wooding, gives information on the meaning of the significant period. 



Arakawa and Suda (1953) summarize and discuss some wave obser- 

 vations made by the Japanese Navy during a typhoon which occurred on 

 September 26, 1935. Table 6 of their paper is reproduced in full and a 

 paragraph referring to the table is quoted as follows: 



"Table 6 shows that comparisons of measured and computed values 

 for the MIKUMA gave rather unsatisfactory results. This may indicate 

 that the state of the sea as observed by the main squadron was, to 

 some extent, uncertain. Comparisons of measured and computed values 

 for the wave length and the wave period from the cruiser NACHI on the 

 other hand gave fairly satisfactory results." 



_ It_ should be noted that according to the notation used in this text, 

 L, f , and C are probably what were really observed. 



Table 6. Observed and computed values of velocities, 

 lengths, and periods of wind waves in the 

 typhoon area, Sept. 26, 1935 



48 



