CONSIDERATIONS AFFECTING DESIGN OF HARBOURS. 149 



conditions of wind and weather on a part of the coast that is much 

 frequented, and is without any adequate place of safety into which 

 vessels may run if overtaken by storms. It should possess (a) easiness 

 of approach, with convenient ingress and egress ; (6) good holding- 

 ground and secure anchorage in various depths for all commercial 

 purposes, including the fishing industries, and for a small squadron 

 of war-ships; (c) facilities for obtaining ordinary supplies and for 

 executing the smaller class of repairs ; (d) natural capabilities for 

 the construction of efficient works of defence at a moderate cost. 



" A ' special ' or * national ' harbour of refuge is one whose 

 position is influenced mainly by strategical considerations and 

 imperial policy, a refuge harbour in the sense of shelter from an 

 enemy as well as from storms. In a ' national ' harbour fresh con- 

 siderations present themselves, such as the following : 



" (a) Its position should be central in reference to the defence of 

 some important part of the coast and of the shipping frequenting it, 

 and at the same time convenient for observation of the movements 

 of an enemy. 



" (6) A larger area of anchoring-ground in depths sufficient for 

 the heaviest-draught ships of war is required than iu the * general ' 

 harbour of refuge. 



" (c) It should be, with a view to the concentration of troops and 

 military stores, in connection with the railway system of the country, 

 and should possess facilities for the supply of coal, and for the 

 smaller and immediate repairs demanded by a squadron of large 

 ships. 



" ' Local ' harbours of refuge are those of which the sites can be 

 determined only by local demands, and their area and capabilities 

 by local requirements, it being understood that the term * harbour 

 of refuge,' when applied even under these limited conditions, carries 

 with it easiness of approach, and a sheltered anchorage at all states 

 oE tide for vessels of a moderate draught of water." 



In laying out a plan for sea-works, advantage should be 

 taken of any natural features which can be turned to account, 

 such as channels or indentations of the coast, ridges of rocks, 

 and so forth. The adaptation of designs to such features must, 

 however, be kept within reasonable limits ; otherwise, so far from 

 being advantageous, they may prove detrimental to the work. 



