of available data. Detailed weather data and wave data 

 were obtained for the period from 22 April to 31 May 

 1958. In general good agreement between observed and 

 forecasted significant wave heights is obtained. Sta- 

 tistical study of results indicates forecasted significant 

 periods are not accurate and are not distributed accord- 

 ing to the distribution of observed significant periods. 

 It is shewn that forecasted values for deep water were so 

 inaccurate that verification of the refraction diagrajn 

 for Long Branch, N. J. was not possible. The data are 

 considered sufficiently accurate to permit qualitative 

 discussion of problems connected with beach erosion. 

 SMne of the effects of an east coast storm on the shore- 

 line are described, and statistical properties of east 

 coast storms given. 



NO. 25 - November 1951 



II-C "The Slope of Lake Surfaces Under Variable Wind Stresses" 

 by B. Haurwitz 



The inclination of a lake surface caused by a wind stress 

 shews a distinct time lag in adjusting itself to changing 

 winds. This phenomenon is analyzed utilizing hydrodynamic 

 equations simplified by integrating over the whole depth 

 of the lake, and it is found a priori that the time re- 

 quired depends on the length of the seiche periods. Parti- 

 cular attention is given to a wind shift which took place 

 during the passage of a hurricane, 26-27 August 1949, 

 over Lake Okeechobee, Florida, when the wind turned through 

 about 180 degrees during a time of roughly three hours. 

 The turning of the wind was accompemied by a turning of 

 the height contours of the lake surface, but the latter 

 rotated more slowly so that for some time the wind blew 

 parallel to them. It is shown that the theory explains 

 this behavior of the lake surface. 



NO. 26 - November 1951 



II-C "Sand Movement on the Shallow Inter-Canyon Shelf at La Jolla, 

 California" by F. P. Shepard and D. L. Inman 



The nature of changes in sand level of a beach and shallow 

 shelf area between two submarine canyon heads has been 

 indicated by eight repeated surveys accompanied by five 

 sampling operations, which are believed to establish sig- 

 nificant changes out to depths of at least 100 feet. Wave 



85 



