and wind velocities. The propagation velocity 6" and the wave 

 length A are computed, by means of Gerstner's formulas, from the 

 period T, The fetch is given "by the distance from the coast to 

 the ship's position in bearing the direction of wind. 



Fig. 24 represents these new observations, augmented by older 

 estimates which were collected and used by H. U, Sverdrup and W, U. 

 Munk [1], and by two observations of V. Cornish (see H. Thorade [6]). 

 For comparison with theoretical results, these data are plotted 

 into the fetch-graph p = cp / •^1 . The observations are in fair agree- 

 ment with the theoretical curves. In the region of low fetch para- 

 meters, the observed values p for all wind velocities fit the theo- 

 retical curve very well, but for higher fetch parameters, the single 

 observations spread out into the region on the right hand of the 

 curve, as it is to be expected when the p -waves have attained 

 their fully arisen state. Theoretically, this is indicated by 

 the straight lines which branch off at certain fetch parameters de- 

 pending upon the wind velocity. Thus, in this region we have obser- 

 vations at fully developed p -waves, but, besides these waves, 

 p(l)-waves and finally B ♦-waves may be observed, if the fetch 

 is long enough. The growth of these longer waves at different 

 wind velocities is represented in the fetch-graph by curves which 

 branch off to the top of the graph. In the fully developed state, 

 the observations of p values (computed from observed "periods" at 

 given wind velocities) range between the upper straight line and 

 the lower straight line for the given wind-velocity, but a "piling 

 up" of observations is to be expected around the lower line (p_), 

 the upper line with ^^* = 1.37) and p = 1. The distribution of 

 p-values as computed from observed 'periods" T in fully developed 



119 



