PIER-HEADS. 



223 



upon vessels coming into collision with it, or to sustain damage 

 itself by vessels striking it, than one of more rectangular form. 



Fig. 50, Type C, represents a head of hooked form, in 

 which the advantages of a circular head and of a spur are 

 combined. 



Harbour Side 

 FIG. 55. Pier-head, Type B. 



FIG. 56. Pier-head, Type 0. 



The superstructure of the Holyhead breakwater terminates 

 with a hammer-shaped head (Type D, Fig. 57), which is founded 

 at the level of 20 feet below low water. This somewhat ex- 

 ceptional form was adopted in order to prevent small rubble 



\Lighthoiist: 





Seaward Side 



FIG. 57. Pier-head, Type D. 



from the mound travelling around the end of the breakwater, 

 and also to give protection to the end of the mound itself; it 

 furthermore, in a measure, shelters the landing-steps on the har- 

 bour side of the pier from waves wheeling round the end. 







