68 The Evolution of Floating and Other Dry Docks. 



Subsequently in 1869, a jBoating dock capable of lifting a vessel 

 of 10,000 tons weight was built to Rennie's designs for Bermuda, 

 on the " Balance" system and U section, with numerous water- 

 tight divisions and decks, the object being to self-careen the 

 dock for cleaning or repairing the bottom, but the stability was 

 not all that could be desired, and when taken out to Bermuda 

 the operation of careening was never attempted, and in 

 consequence corrosion rendered the dock inoperative. The 

 cellular portion was subsequently partially filled with concrete 

 and the dock is now used as an ordinary graving dock with end 

 gates fitted. 



Bramwell's Dock. 



The next improvement is to be found in Sir Frederick 

 Bramwell's dock, designed and constructed for St. Thomas. 

 The pontoons were independent and could be detached for self- 

 docking, but the walls were continuous lattice girders, to give 

 the structure a certain rigidity absent in the sectional docks of 

 America. It is regrettable to note that the merits of self- 

 docking were not universally adopted in subsequent designs 

 until a later period ; now all floating docks are so designed that 

 they can be docked in sections, or all parts made accessible in 

 some convenient manner. 



Depositing Dock. 



The first modern side depositing dock was the NicolaiefF 

 Dock, designed by Messrs. Clark & Stanfield, and constructed 

 in 1878; it has since been removed to Sebastopol. The 

 principal merit is its capacity, it can lift and deposit on a 

 suitable gridiron a number of vessels, or the lifted vessel may 

 remain upon the dock if convenient. Another commendable 

 feature is, that vessels of abnormal beam such as paddle steamers, 

 or the Popoif ironclads, can be dealt with on this type of dock 

 without necessarily increasing the beam of structure. The 

 stability of the dock when submerged is provided for by a 

 floating counter-balance, which is somewhat in the way when 



