CONTENTS. xiii 



CHAPTER XIV. 



DIFFERENT METHODS OF CONSTRUCTING BREAKWATERS. 



PAGE 



Staging Barges Cranes or over-end setting-machines Facilities afforded 

 by staging in constructing rubble-mound breakwaters Holyhead break- 

 water staging Sea-staging of ordinary type Mode of depositing rubble 

 at Holyhead Mode of constructing Alderney breakwater Aberdeen 

 breakwater staging General remarks on staging Facilities afforded by 

 staging in building block-work, etc. Cost of staging Bubble mounds 

 formed by means of barges Advantages of steam-barges Bags of con- 

 crete, also concrete blocks, placed by barges Barges and staging com- 

 pared Various types of setting-machines Block-lifting appliances- 

 Diving Mound breakwaters constructed by over-end tipping . . 236 



CHAPTER XV. 



FOUNDATIONS. 



Founding upon rock Difficulties attending execution of work near low water 

 Benching rock Steeply inclined strata Advantages of staging as 

 compared with over-end machines in preparing foundations Under- 

 water mass-concrete foundations Levelling foundations with small 

 broken stone Grouting Founding upon sand Curved profiles Mud 

 Pilework foundation Founding upon gravel Founding upon clay 

 Founding upon rubble mounds 257 



CHAPTER XVI. 



SETTLEMENT AND BOND. 



Settlement can seldom be altogether avoided Usually greatest in break- 

 waters of mound type Increased by weight of superstructure Unequal 

 settlement Weight of heavy setting-machines injurious to new work 

 Settlement of breakwaters at Holyhead, Alderney, Colombo, Mormugao, 

 and Manora (Kurrachee) Bond Objections to Vertical bond Evils 

 attending " dry bedding" of blocks Objections to " stretchers " Dowels 

 Notching Tabling Dovetailing Absence of bond in Manora break- 

 water Sloping coursed work accommodates itself to settlement Bond 

 of block-work in Tynemouth breakwaters 275 



CHAPTER XVIL 



SILTING. 



Process described Wavs and current action Effect of piers projected from 

 the shore Advance of foreshore Prolongation of jetties Dredging 

 Sluicing Harbours on sandy coasts Outlying isolated breakwaters 

 Direction of drift ... 284 









