328
HISTORY OF ENGINEERING.
Book I.
in thickness 14^ inches, and at the heel 16£ inches; each gate, which may be considered asolid mass of oak timber, the planking only being fir, has two cast-iron sluices, 3 feetsquare, witli a rod, worked at the top by an iron screw.
To open and shut the gates, there is a 6-inch iron pinion, which works in a cog wheel,4 feet diameter, round the cast-iron axis of which the gate chain winds.
Over the centre of this lock is an iron swivel bridge, in length 81 feet 9 inches, and inbreadth 12 feet 3 inches; it forms a segment of a circle, and meets in the middle. It iscomposed of six cast-iron ribs, 2 inches thick at top, and inches on the lower edge, unitedand braced together, and covered with 2^-inch oak plank. A cast-iron plate, 11 feet9 inches diameter, is firmly bedded on a pier of brickwork on each side: this has a pivot inthe centre, which works in a socket underneath the bridge; revolving between this circularplate and another on the underside of the bridge are twenty conical rollers, 10^ inches indiameter at one end, and 9^ inches at the other ; these are 6 inches long, and are fitted intoa frame. A man can open and shut this bridge by means of the machinery attached,which consists of two 8-inch bevel pinions, one of which receives the handle ; at the bottomof the other is a vertical shaft, which has fixed on it a 9-inch pinion, which works in aspur-wheel, 4 feet in diameter ; on the axis of this is another pinion, 12 inches in diameter;this works in a toothed segment at the outer end of the bridge, and turns it.
The entrance basin to this dock, 267 feet in length, and 435 feet in breadth, has itswalls constructed in a similar way to those to which it belongs; at the top they are inthickness 6 feet, at the bottom 10 feet; they are faced with stone from Bramley Fall, andhave a similar coping. The walls rest on three rows of piles from 16 feet to 18 feet long,and in front is a row of sheeting piles, with transverse sleepers, closely planked over.
The mooring posts are placed 30 feet apart, and about 12 feet from the sides of the lock.
The Junction Dock, 645 feet in length, and 407 feet in breadth, was commenced in1826, from the designs of Mr. James Walker, and contains an area equal to 6 acres. Twocoffer-dams were employed ; that next the Humber dock was 220 feet in length, forming acurve, the versed sine of which w*as 61 feet. It was formed of two rows of close piles,6 feet apart, and after the mud was taken out, filled in with well puddled clay : the pileswere of whole timber, about 40 feet in length. In front, on each side, were forty-two gaugepiles with two row's of waling pieces, 13 inches by 8, well bolted. Rough iron tie rodswere also introduced to prevent the work from yielding ; against this dam was a pressureoccasionally of 28 feet of water, which found its way along the cross braces, but wasspeedily stopped.
The other coffer-dam, at the west end of the old dock, a curve of 115 feet in length, witha versed sine of 14 feet, was formed in a similar manner.
The water was pumped out by tw T o six-horse steam-engines, and the sides of the dockwere excavated with a slope of one horizontal to one vertical. The average depth of theexcavation was 19 feet, and the quantity of clay and earth removed was about 300,000cubic yards.
Under the dock walls were driven 2401 piles, containing 18,500 cubic feet of timber,and 2140 feet in length of sheet piling, 12 feet in depth, and which cubed to 12,840 feet;on the heads of some of these piles it has been calculated there is a superincumbentweight of 20 tons.
Below the sleepers, the space is filled up with brick rubbish puddled or grouted withhot lime and sand, and at the foot of the wall is a similar bed of concrete.
The wall is of brick, partly faced with Bramley Fall stone, in 12-inch courses; thisextends from the coping about 11 feet 9 inches downwards; the two lowest courses are,however, of stone from Barnsley or Whitby, both fine sandstones, and each 15 inchesthick ; every two stretchers have one header, which are each 3 feet 6 inches long : the wholeis coped with similar stone, 4 feet in width, and each joint is secured with a 4-inch squaredowel.
The walls are curved about 7 feet on the oast and west sides.
The locks within the gates arc in length 120 feet, and in width at the top 36 feet6 inches : they are in height above the pointing sills 25 feet.
The lock gates, formed of English and African oak, are cased with 3-inch fir planking ;they are hung at top with a wrought-iron collar, in a cast-iron anchor, let into the stone-work ; the heel-post has an iron socket, which turns on a brass pivot; the outer end ofthe gate is supported on a brass roller, 12 inches diameter, and 4 inches wide; to this isattached an adjusting screw : the roller moves in a brass segment, let into and screweddown to the platform. To work these gates, on each side is the machinery, which is fixedinto a cast-iron box ; it consists of a 7-inch pinion, which works in a spur-wheel 4 feetdiameter, on the axis of which is a cast-iron roller, 3 feet long, and from 12 inches to9 inches diameter; a three-quarter inch chain winds round this, and passing under a rollerat the bottom of the wall, and over another, in the face of the •walls, is fastened to the gate.There is attached, as in the other locks, a counterbalance weight and chain. Each gate