between succeeding crests ("periods" in complex sea) at a fixed 

 point may be compared with the diagram in Fig. 3 of Chapter I, 

 which represents the results of observations. At a wind velocity 

 of V = 16 m/sec the characteristic "periods" vary over a range of 

 about 8,5 seconds, that 3s, between 6.5 sec and 15 sec. V/ith the 

 appearance of typical interference phenomena and groups of waves, 

 a certain regularity is to be expected in the occurrence of high 

 breakers (see Chapter I). 



8) Com p arison of theoretical results wi th o bservations 



Special attention was paid to observations on waves when the 

 "Heidberg" sailed or anchored under the protection of windward shores. 

 This opportunity arose during a longer stay at San Miguel (Azores) 

 and in many cases at the coasts of Venezuela and Colombia, in the 

 northern parts of the Caribbean Sea, and in the Straits of Florida, 

 and in the Gulf of Mexico. 



The "Heidberg"-observations at lim i ted fetches comprise the 

 range of wind velocity from 1.7 ta/sec to 13 ni/sec with two single 

 measurements at I6 and 18 m/sec wind velocity and fetches of 400 

 and 450 m, respectively,. There are included some observations at 

 low wind speeds made at the German coast of the North Sea (Islands 

 of Sylt and Amrum) in the summer of 1950, and an observation at 

 V = 7 m/sec made in Vineyard Sound during the author's stay at Woods 

 Hole in the summer of 195l» The results of these observations are 

 presented in an appendix to this report, because measiirements of 

 the growth of waves are still rather scarce. The table contains 

 in some cases measurements of the wave height H, besides the observ- 

 ed characteristic period (or periods) T at different fetches. and 



118 



