HARBORS, &o. J 07 



B. The Roadstead. 



This is a place of anchorage where vessels may lie at anchor more or 

 less protected from storms, for the purpose of discharging or of taking in 

 a portion of their freight. A roadstead is either inclosed or open {pi. 31, 

 fg. 1, where a division of a fleet is lying at anchor) ; in the latter case it is 

 only a good landing, but affords no protection to ships, except a conve- 

 nient anchorage. An inclosed roadstead (Jig. 2) is so surrounded by 

 the land and the adjacent heights, that it protects vessels from the ocean 

 winds. 



C. Docks. 



A deep basin is usually made on one side of a harbor, or in large rivers, 

 which is filled with water by means of sluice gates, and is then again laid 

 dry by means of special sluices on the sides. Ships are sometimes taken 

 into these docks, for loading and unloading ; but they are most generally 

 brought in to be repaired. The docks are so arranged, that they are of equal 

 height with the low-water mark, so that the ship can be taken in and out 

 at flood-tide. This kind of docks is called wet docks. Dry-docks are those 

 mentioned above, which can be laid dry by means of special sluice gates. 

 PL 32, Jig. 9, shows a section of the Dundee Dry-dock. Fig. 10 is a 

 view of one half seen from above. Fig. 11 is one half the transverse sec- 

 tion at the end, and^^; 12 one half of the transverse section near the sluice 

 gate, a is the dock, b the stairs leading to the bottom, c the sluice-chocks, 

 d the gate, e the floor, the forward floor, g and h locks for letting the water 

 off* and on, i and k openings to the sluice gates. 



Fig. 1 1 shows the blocks on which the staging for the ships is placed. 

 PL 30, Jig. 1, shows the dry dock in Toulon harbor. In it are two ships 

 building. Another construction is shown in the Prince's Docks at Liver- 

 pool, of which pL 32, Jig. 3, shows a transverse section of the chamber, 

 Jig. 4 a transverse section near the mouth of the sluice. Jig. 5, the profile of 

 the western wall, and Jig. 6 the profile of the same wall near the sluice- 

 mouth. Fig. 7 is the profile of the wall of the London dock. It is lined 

 with iron. Fig. 1 is the ground plan of the West-India docks in London 

 They are wet docks, intended only for loading and unloading vessels. On 

 their account store-rooms are built in their vicinity. The South docks and 

 Timber docks are used for repairs. Harbors and docks, where they adjoin 

 the water, are provided with quays, up to which the ships can be brought. 

 These quays are of considerable height, with deep sides, and are usually 

 built of stone. Fig. 8 shows the profile of the Mersey quay in Liverpool. 



D. Ship Yards and Machines. 



A good harbor is usually provided with ship yards, places where new 

 ships can be built on the stocks, and old ones brought in for repairs. 

 In a ship yard, there are ways, which are dry at ebb-tide (pL SO, fg. 3), 

 on which the ship is placed by the tide or by machines, when it can be laid 

 on its side, and new coppered or caulked and graved (Jig. 4). There are 



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