194 HARBOUR CONSTRUCTION. 



Irregularities in the foundations can be readily levelled up 

 by the use of concrete in mass or in bags, or by broken stone, 

 according to the depth of water and exposure of the site ; and 

 inequalities at the quay-level may be adjusted by means of a 

 capping of mass- work, similar to that represented in Figs. 30, 

 32, pp. 180, 184. 



Rapid progress may be made with work constructed on this 

 principle, and the scar-end 1 can be easily and effectually secured 

 against heavy seas. It may, moreover, be made much shorter 

 in proportion to its height than is possible with horizontal 

 courses; consequently the machine used for setting the blocks 

 need not have so great an overhang, and its cost and weight 

 will, as a matter of course, be proportionately reduced. 



The setting machine, or "Titan," used in constructing the 

 Colombo breakwater, on the above system, was adapted for 

 lifting loads up to 40 tons, and it had an overhang of 28 feet. 

 That at Mormugao was of somewhat similar design, and was 

 adapted for dealing with loads up to 45 tons, its overhang 

 being about 25 feet. 



Blocks weighing 27 tons each were employed in constructing 

 the Manora breakwater (Kurrachee), which is also built on the 

 sloping-block system. The machine used for setting these was 

 almost identical with the one used at Mormugao, but its over- 

 hang was slightly less. 



The inclination of the blocks in this breakwater was 1 in 

 4 (about 76). 



At Reunion harbour, where the same method of construction 

 was adopted, blocks weighing as much as 113 tons each were 

 placed in the work at a short overhang, and others weighing 

 40 tons each were laid at an overhang of about 42 feet. 



In illustration of this system of construction, sections and 

 part elevations of the Colombo and Mormugao breakwaters 

 are given in Fig. 38 and 39. They are, as will be seen, composite 

 structures; but, omitting the rubble bases, they furnish good 

 examples of the type of breakwater we are now considering. 



1 The scar-end is almost always a vulnerable point. When the season's work 

 is over, and before winter gales begin, every care should therefore be taken to 

 secure the work by cramping or tying together several of the end blocks in each 

 course (assuming the work to consist of blocks). Sometimes the stepping of the 

 courses is temporarily built up with masonry in order to do away with the re-enter- 

 ing corners, and so present a more even surface to the waves. 



