ENGINEERING WORKS, ETC.
973
cylinders being 14 inches in diameter, and the stroke 18 inches; they wereplaced closely together, with the valves outside worked direct from theeccentrics. The engines were bolted down to water tanks placed on eachside of the dock. The boilers were round, carrying a pressure of 40 lbs. persquare inch, the diameter being 5 feet 6 inches, and the length 8 feet6 inches; furnace 2 feet 9 inches diameter, with tubes arranged aroundthe sides and at top onthe return principle. There were 86 tubes, 2 inchesdiameter, 7 feet 2 inches long, and number 7 wire gauge, and 6 tubesat bottom, three on each side, 3 inches diameter, 7 feet 2 inches long, andnumber 9 wire gauge. These large tubes at the bottom were introducedto induce a downward draught, which they did effectually.
Pumps .—There were four pumps to each engine, 20 inches in diameter,with a stroke of 2 feet 9 inches, driven by two pinions and four spur wheelsto each engine. The rods for working the pumps were connected to a pinon each spur wheel. As the rods were long they had wrought-iron endsand wooden distance pieces, the wood being embraced with Straps andbolted through and through the wrought-iron jaws, thus a strong and lightrod was obtained.
These docks were merely temporarily put together in this country. Allthe plating, lattice girders, &c., were simply held together with bolts andnuts. All the butts of the plates were planed and machine punched,taking three holes at a time. The punching machines had tables movedby hand, and templated and punched the plate at one movement. Thesemachines are invaluable for this dass of work; indeed, in such large under-takings, hand labour is out of the question. The pitch of the rivet holeswas 2^ inches, and the diameter of the rivets ^ inch, and there wereabout 1,300,000 rivets in the dock. The weight of the wrought iron, notincluding the engines or machinery, was as follows:—
Hüll, .3594 tons.
Pipes and bearers, ... ... ... ... ... ... 95 »»
Total,
3956
NAVIGABLE FLOATING DOCK AND BATTERY, DESIGNED BY THE
AUTHOR.
In the construction of the second dass or navigable floating dockit is obvious that a different form from the preceding must beadopted. Such docks possess great advantages over the formerdass, not merely in having the means within themselves of movingfrom one Station to another, or in following a fleet in time of war;but their first cost is greatly reduced; for the labour of putting up at