14 NOTES ON DOCKS AND DOCK CONSTRUCTION. 



regards provision for vessels of great draught. The depth 

 of water over the sill of the lock at equinoctial springs is 42 

 feet, at ordinary springs 38 feet, and at ordinary neaps 26 feet, 

 whilst the depth of water constantly maintained in the dock 

 is 26 feet. 



The Alexandra Dock at Hull l (Fig. 8), constructed from the 

 designs of Mr. J. Abernethy, is 2200 feet long, by a total width 

 of 1000 feet, with a water area of 46J acres. 



On the south side the entrance lock projects 400 feet into 

 the basin through a jetty of 250 feet width, leaving 600 feet 



2500 FEET 



FIG. 8. 



as turning room, or, with a ship alongside the north wall, 550 

 feet clear. 



On the south side, between the lock and the east wall, there 

 are three masonry jetties 400 feet long by 100 feet wide. On 

 the west side there is also a masonry jetty 550 feet long by 100 

 feet wide. In this example, the jetty system has been taken 

 advantage of to the utmost, giving an available wharfage 

 accommodation of about 8500 feet, or sufficient for 21 ships 

 averaging 400 feet in length. The depth of water in the basin 



> M.P.1.C.R, vol. xcii. p. U\. 



