Although insular breakwaters are often constructed in harbors, the 

 interaction between an insular breakwater and water waves has not been 

 clearly defined. This report presents the exact solution of wave reflec- 

 tion and diffraction by a vertical, elliptical cylinder with a series of 

 Mathieu functions. The solution coincides with the solution for a circu- 

 lar cylinder when the circle is taken as an asympotic figure of an ellipse, 

 The exact solution for a straight insular breakwater is derived from the 

 deformation of the elliptical cylinder into a plate of infinitesimal 

 thickness. Wave- height ratios of scattered waves to incident waves have 

 been calculated near insular breakwaters, and the application limit of 

 the approximate solution is determined from the comparison between the 

 exact and the approximate solutions, 



48. GRANGE, M.A., Untitled Report to SII-CI (Protective Works Adopted 

 to Limit Erosion Along the Open Coast; How They Work, Reference to 

 Model Experiments), XVIIth International Navigation Congress ^ Lisbon, 

 1949, pp. 63-74 (in French). 



Keywords: Accretion, Compartmented breakwater, France (Anse des Huttes, 

 Arros, and Pointe de Grave) 



This paper refers to a report on the principles adopted for protec- 

 tion of coasts against erosion and practical considerations for construc- 

 tion of such works, presented by M. Kauffman at the Congress of Venice 

 in 1931, The conclusions of that report remain valid. The paper dis- 

 cusses several works created on French coasts: 



(a) Prefabricated, reinforced concrete structures built 

 on the channel coasts; 



(b) the replacement of framework structures by masonry 

 structures in Normandy, especially at St, Valery en Caux; 



(c) the use of openwork groins of reinforced concrete 

 stakes, braced longitudinally and transversal ly by wooden 

 joists, in the Basse-Camarague region on the Mediterranean 

 coast; and 



(d) the construction of a groin made of natural rock 

 blocks at Hendaye. 



The second part of the paper is a historical survey of the works 

 undertaken during the last 100 years around the Pointe de Grave, which 

 borders the outlet of the Gironde to the south. 



49. GRANT, U.S., and SHEPARD, F.P., "Shallow- Water Sediment -Shifting 

 Processes Along the Southern California Coast," Proceedings of the 

 Sixth Paoific Scientific Congress^ Vol. 2, 1939, pp. 801-805, 



Keywords: California (Santa Monica), Littoral transport. Sediment 

 sizes 



22 



