FETCH, EXPOSURE, AND WAVE-POWER. 



81 



at A, Fig. 14, excavate the rock, and, rushing down the slope C 

 like a torrent, fall into the sea on the other side of the headland. 



In reference to the effect of falling water, I ask the reader to 

 note that a velocity of 41 feet per second, being that of the 

 storm -waves referred to on pp. 39 and 41, is that attained by a 

 free body falling through a distance of 26 feet. 



It is no uncommon occurrence for storm-waves, striking a 

 vertical breakwater face, to throw heavy masses of water to a 

 height of at least 100 feet often very much higher. 



Such water in its descent, on reaching the roadway of the 



Scale I inch 80 feet. 



,f~. 



**<*-<, . 4 ~^~^^S~^^ r 



Heaf> of debris; many of the stones 

 weighing from 8 to 10 ciuts. 



Fro. 15. Sketch showing effect of waves at Ifollurn Head, Caithness. 



breakwater upon which it falls, will have attained a velocity of 

 about 80 feet per second, or nearly double the velocity and four 

 times the force of the water striking the face of the breakwater. 

 Although the volume of the water thus falling is less than that 

 of the wave, it is, nevertheless, often very great, and clearly 

 points to the necessity of providing ample strength and close, 

 well-made joints in the roadway of a breakwater occupying an 

 exposed position. 



In view of the foregoing, there would seem to be little cause 

 for wonder that so many breakwaters have suffered damage 



G 



