For a limited opening the distribution of the amplitudes that 

 one obtains presents "tongues" or "leaves** of the agitation analogous 

 to those noted in normal incidence; and moreover they are more 

 numerous as the opening is made larger with respect to the length 

 of the wave. If one examines the area at quite a distance from the 

 opening the agitation is found to take a very simple form analogous 

 to that which characterizes the emission from radio antenna systems. 

 The maximum agitation is found on the axis of the opening extended 

 parallel to the direction of propagation. If one expresses all the 

 horizon bal distances in terms of wave length it is equal to the 

 length of the opening projected on the crests of the incident wave. 

 Very close to the opening maximum agitation approaches the down- 

 stream arm of the breakwater, i.e. the one reached last by the 

 incident wave. The maximum amplitude possible is 1.36 tines the 

 amplitude of the incident wave. 



According to some figures presented in the article of Morse 

 and Rubenstein (6) the exact solution ought to present "tongues" 1 

 or areas of secondary maximum agitation. In the actual state of 

 the question, development is left to reduced scale model experi- 

 mentation since verification of the results is required. 



BIBLIOGRAPHY 



H. Lacombe - Note sur la diffraction de la houle en incidence 

 normal©, Annales Hydrographiques de 194-9 ou 

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Lamb - Hydrodynamics, 6th edition, Cambridge 1932. 



H. Bateman - Partial differential equations of mathematical 

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J. A. Putnam et R. So Arthur - Diffraction cf Water waves by 



breakwaters. Trans, Amer. Geophys. Union, Vol. 29, 

 No. 4> Aout 194.8. 



F. L. Blue et J. N. Johnson - Diffraction of water waves passing 

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P. Mo Morse et P. J, Rubenstein - The diffraction of waves by 

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Larras - La deformation ondulatoire des jetees verticales. 



Travaux, Juin 1942. 



E. Mathieu - Cours de physique mathematique . Gauthier-Villars 

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L. de Broglie - Problemes des propagations guides s des ondes 



electromagnetiques. Gauthier-Villars, Paris 1941. 



P. Levy - Gours d' analyse de l'Ecole Polytechnique. Tome II, 

 1934, p. 267-268. 



IS 



