458 



Proceedings of the Royal Irish Academy. 



or damaging the shipping in it, by placing a breakwater (e, fig. 7) 

 across the direction {arroiv'S>) from which the preTailiiig storms come. 



Fi&. 7. 



If such a breakwater were a fi:s;ed one, built of stone or wood, it must 

 more or less affect the tidal di-iftage, and probably would help to fill up 

 the harbour. But if it was floating, it ought to break the wind-waves 

 in deep water, thus desti'oying theii' drifting powers, while there would 

 be no impediment to interfere with the tidal diiftage. The exact fonn 

 of the pier, whether straight, or slightly ciuwed, as represented in the 

 figure, would have to be deteiiniaed on, after experiments on the sets 

 of the currents, at the place where the pier was to be built. 



