i;8 HARBOUR CONSTRUCTION. 



The ill-fated breakwater at Wick, which occupied a very 

 exposed position, was of a somewhat similar design. When 

 inspecting its ruins a few years ago, I was informed, by one 

 who had witnessed its destruction, that the inner or harbour 

 wall was the first to give way, it having been thrust out by 

 the weight of water falling upon the roadway. The outer or 

 sea wall stood for some time after the harbour wall had 

 succumbed ; but, on the rubble hearting being ploughed out by 

 successive seas, it lost its support, and was overturned by the 

 force of the waves. 



///'* k^c '""" 



FIG. 29. Kilrush pier. 



The failure of the St. Heliers (Jersey) landing- pier was, in a 

 great measure, due to the same cause. 



Exceptional risk is incurred during the construction of break- 

 waters of this description. The side walls are advanced, and 

 have to stand unsupported until the rubble is filled in between 

 them, as far as the cross- walls placed, it may be, about 30 feet 

 apart will admit. This having been done, a heavy gale pro- 

 bably occurs before the rubble can be protected, and the cavities 

 are all filled with water. Upon this the masses of water which 

 are thrown up by waves striking the face fall, and the resulting 

 pressure, acting like a force-pump, bursts the work asunder, as 

 just described. 



