FOR GREAT BRITAIN AND IRELAND. 51 



a skilful engineer could not have protected the coast 

 better than has been accomplished by the dip of the 

 strata." 



" This remark of Sir Henry's suggests another source of 

 danger which ought not to be overlooked. If a sloping 

 direction of the strata have the effect of reducing the force 

 against the coast, by altering the direction of the surf, it is 

 equally clear that where long ledges of rock cross the line 

 of direction of a proposed pier, there may be expected an 

 intensified action at the points of junction. Long ledges 

 of rock, though affording useful shelter where the works 

 run parallel with them, are therefore sources of danger 

 where this parallelism cannot be preserved in laying out 

 the lines of the piers. All attempts to carry works across 

 those long narrow chasms which separate rocky ridges 

 (ledges), or even to cross creeks of considerable width, 

 must be regarded as peculiarly hazardous, and special 

 provisions are required for resisting the concentrated 

 action which is common to these and all such places where 

 the sea is gorged'' 



"It must, of course, be understood, that cases occur when, 

 in order to afford sufficient harbour room, or to effect some 

 particular object, it becomes necessary to erect sea- works 

 in situations where the pent-up waves must be fully 

 encountered." 



" The sea-wall of the Victoria Harbour at Dunbar is an 

 instance of this kind, for the basin which had to be 

 enclosed occupied the landward portion of a narrow creek. 

 The outer wall has therefore not only to check, without 

 any lateral relief, the whole of the waves, which formerly 

 dashed into the creek, but, owing to the outline of the 

 coast, it has also to encounter them nearly at right angles 

 to their direction." 



E 2 



