196 HARBOUR CONSTRUCTION. 



The Colombo breakwater was designed by the late Sir John 

 Coode, and was carried out under his direction by Mr. J. Kyle, 

 M. Inst. C.E. That at Mormugao was designed by Messrs. 

 Hawkshaw, Son, and Hayter, Mr. E. Sawyer, M. Inst. C.E., being 

 the executive engineer. 



In the latter work a wave-breaker, composed of 20-ton 

 concrete blocks, was introduced, its object being to protect the 

 toe of the superstructure from scour or undermining. 



There is no wave-breaker to the Colombo breakwater, but 

 the rubble at the toe of the upright work is protected by an 

 apron, 24 feet wide, composed of 10-ton bags of concrete. 



The wave-breaker at Mormugao appears, however, to have 

 been more effective than the apron at Colombo, inasmuch as 

 in the former case practically no expenditure has been incurred 

 for maintenance, while at Colombo the mound foreshore has 

 required a good deal of attention. The two sites, as regards 

 exposure, etc., are very similar, as are also the main features of 

 the breakwaters themselves. 



All the blocks in the Colombo breakwater are bonded 

 together, not only by "breaking joint" with each other, but also 

 by means of joggles of large size, formed by filling grooves with 

 concrete in bags, as indicated in Fig. 38, p. 195. There are five 

 of these grooves in the width of the breakwater, and they 

 extend continuously from top to bottom of each course of blocks. 

 The blocks in this breakwater vary in weight from 16 J tons to 

 30 tons, and they are inclined at an angle of 68 to the horizon. 



In the Mormugao breakwater tongues or projections on the 

 top of the blocks, measuring 4 feet 6 inches wide by 2 feet 6 inches 

 deep, and fitting into corresponding grooves or recesses in the 

 superposed blocks, take the place of the joggle grooves, excepting 

 in the uppermost blocks, which are dowelled to those below them 

 by means of pieces of rail, this having been found more con- 

 venient than the tongues and grooves for purposes of alignment. 



The blocks in the Mormugao breakwater weigh from 29 tons 

 to 37i tons each, and are set at an inclination of 70, being almost 

 the same as in the Colombo work. 



In setting sloping blocks there is often a tendency for the 

 toe of the work to outrun the top, or, in other words, for the 

 slope to become flatter; but this may be easily rectified as 

 the work advances by introducing compensating courses to the 

 extent required. Every endeavour should, however, be made 



