CHAPTER XIV. 



DIFFERENT METHODS OF CONSTRUCTING BREAKWATERS. 



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

 staging in constructing rubble-mound breakwaters Holyhead breakwater 

 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 Rubble mounds formed by means of barges 

 Advantages of steam-barges Bags of concrete, also concrete blocks, placed by 

 barges Barges and staging compared Various types of setting machines 

 Block-lifting appliances Diving Mound breakwaters constructed by over- 

 end tipping. 



SEVERAL of the methods usually adopted in constructing break- 

 waters have already been referred to, and some of what may 

 be called the secondary appliances have been described with 

 sufficient minuteness. 



The various devices for constructing breakwaters differ, as 

 will have been gathered, very widely from each other ; but the 

 systems commonly adopted may be generally classified under 

 three heads, viz. staging, barges (with or without shears), and 

 cranes or over-end setting machines. 



Staging is applicable alike for depositing rubble, laying 

 bag-work, putting in mass-work, setting blocks, or building 

 masonry ; but the question whether a stage is the best to employ 

 in any individual case must, in common with other systems, 

 depend upon circumstances. 



Barges are frequently used for depositing rubble in mounds 

 where the depth of water is sufficient to admit of this being 

 done. They are also used for depositing bag-work, as well as 

 blocks of concrete in pell-mell work. When used for this latter 

 purpose, they are usually, though not always, provided with 

 powerful shears. 



