60 



THE MADRAS HARBOUR. 



on without some consideration as to their necessity and their 

 superiority to other modes of attaining the desired purpose. 



24 feet, 



High 







Water. 



Low 



Water. 



r 







1 



; 



• 





Hubble Stone Base. 



Cross Section of Superstructure. 



It would require too much space to describe fully the 

 grounds upon which the several features of this form of 

 breakwater were determined on, but one or two points are 

 necessary to make what follows intelligible. 



Many years ago one of the questions under warm discus- 

 sion among engineers was the relative merits of an upright 

 wall or a flat slope to withstand the force of the waves. On 

 the one side it was argued that as the effect of the sea was 

 to form shingle, sand, or any other moveable material into 

 a slope more or less flat, as is seen on every beach, the 

 outer face of a sea barrier should take the form nearest to 

 that which the sea would make for itself. On the other 

 hand it was said that as the sea has beaten for ages against 

 the upright faces of granite or basalt rocks without affect- 

 ing them, so it would do against an artificial face of equal 

 solidity. 



Much learned theory as to the nature of wave movement 

 was advanced on both sides, but the question seems now 

 to have resolved itself into one of money. Successful sea 



