972

MODERN STEAM PRACTICE.

planking secured with screw bolts, a hand rail formed of stanchions ofwrought iron, and round-iron bars being fitted from end to end. A similarhand rail is placed all round the platform at the top of the dock, as like-wise for the staircase from the platform to the top of the basement.

Fenders .—Angle irons 4 inches by 4 inches by ^ inch are arranged onthe sides and the ends vertically for taking the beams of wood forming thefenders, with longitudinal beams at the top and bottom of basement, aslikewise at the top of the middle and floating chambers.

Teak beams .—Above every girder on the floor of the dock are placed teakbeams 24 inches by 18 inches at the centre, tapering to the sides of the sill,having angle iron at the bottom 4 inches by 4 inches by inch, and thefloor of the dock is covered over with teak planking 3 inches in thickness.

Sluices andpiping .—As near the central length of the dock as convenientat the bottom of the sides of basement, two sluice valves 40 inches in dia-meter are placed on each side, having a wrought-iron pipe of the samediameter connected to each, on which branch pipes 18 inches in diameterare fitted for bolting the sluice valves to, one to each water-tight compart-ment, four being placed on the side, and one at the end of the large pipe;to these are fitted wrought-iron pipes in Connection with each compartment,each having a bell-moutbed suction piece of cast iron, conducted to within2 inches of the bottom of the basement. The wrought-iron piping wasstrongly rivetted to the bulkheads, and materially stiffened the structure.These sluices allowed the water into the basement, and when the large onesat the sides were closed the 18-inch sluices regulated the supply to thepumps. Any one of the compartments could be pumped out quite inde-pendent of the others; thus the basement formed the balancing power ofthe dock. In connection with the middle chamber two large sluices40 inches in diameter were fitted higher up on each of the sides of the base-ment, having a large wrought-iron pipe connected to each sluice, with abranch pipe so placed that it came exactly in the centre of one of the open-ings in the lattice girders. A straight pipe was run fore and aft, taperingfrom 40 inches to 18 inches at the end, with branch pipes on top connected totop öf the basement, through which holes were cut into the middle chambers.These pipes were strongly rivetted to the bulkheads, holes being cut form-ing a communication from end to end. The flow of water into the middlechambers was thus regulated by the sluices, and the water simply flowed inand out by gravitation.

Air pipes .—On the top of the basement cast-iron air pipes tvere fittedfrom each compartment, and these pipes were carried to the top of thedock; thus when the water was let into the basement the air was not at allcompressed, but escaped up the air pipes.

Engines and boilers .—The engines were of the high-pressure type, the