periods even briefer than the buoy's own period, could the buoy's 

 oscillations be less than those of the sea. 



For this to have happened, during the observations of the 

 storm of Argel to which we refer, it should have been necessary 

 that the natural vertical period of the buoy itself be significantly 

 greater than the 13 3/4- sedonds, which we estimate to be impossible 

 in a buoy of that type.* 



The maximum height of wave before reaching the dikes was, conse- 

 quently, approximately 7 meters or somewhat less, and only on break- 

 ing over the dikes did this height, amplified** by the works 

 (structure) itself, reach the order of 9 meters, as is demonstrated 

 below „ 



Due to the steep side slopes of the rock fill dikes, or rather, 

 the short distance (relative to wave length) which the wave traverses 

 from the vertical line through the dike toe to the highest point 

 reached on the dike, the energy loss must be small, in spite of 

 the rock fill roughness, always small relative to the wave length. 

 Moreover, even were the energy loss to be appreciable, disregarding 

 it only augments correspondingly and conveniently the margin of 

 safety. 



In a sense (limited, for a breakwater is not a beach although 

 the effects resemble one another for waves of the length under 

 consideration), the graphs of our article published in the Itevista 

 de Obras Pdiblicas last November, in which the curves corresponding 

 to slopes exceeding 10 per cent are almost coincident with those 

 from conservation of energy, may serve to verify the smallness of 

 such energy loss. 



More authentic verification, of this and other simplifying 

 assumptions that are necessitated in these complex subjects, is 

 the comparison with actual observations on the dikes of Argel, 

 themselves, which we make in the following. 



* "Boya de balizamiento" 



-ft* Inclosed in vertical dikes, a similar amplification is produced 

 by the structure itself — amplification which in this case makes 

 the amplitude of the vertical surface movement, on the wall, 

 generally exceed twice the wave height. 



See the booklet Calculo de diques verticales (Calculation of 

 Vertical Dikes), also published in July 1938 and translated and 

 published in the Bulletin of the Inte .national Navigation Con- 

 gress, July 1939. Also see the experimental confirmation of said 

 amplification, constituted by Figure 13 and 18 of the article 

 of A. Stucky and D. Bonnard, published in Travaux of January 

 1937. The results obtained in those publications are likewise 

 admissibly proportioned to the height of wave indicated and its 

 corresponding amplification. 



