Chap. VIII.
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The side walls are supported by brick inverted arches, which are built across the bottom, 6feet wide and 18 inches deep ; the spaces between are 10 feet in width, and the whole is
levelled down with earth to the top of the lock sills.
The Humber dock, in length 914 feet, and in breadth 342, was designed and completedunder the superintendence of Mr. Rennie and Mr. 'William Chapman ; the act of par-liament for its establishment was obtained in 1802, and it was commenced soon after. Jtcomprises an area of a little more than 7 acres. To keep out the tide, during the exe-cution of the work, at the south end a coffer-dam was formed ; its span was 280 feet, and
its versed sine about 140. It was constructed of two rows of Dantzic piles, 7 feet 6 inchesapart; the piles were of whole timber, and well bolted and braced together. In themiddle, at the bottom, was a trunk, and in the space between the rows of piles, bricks laidin sand were built up to the level of high water. The perpendicular head of water pressingagainst it being sometimes 30 feet in height, shores and braces were required to counteractits efforts to drive in the dam.
The water was pumped out by a steam-engine of six horse-power, which worked twoeleven-inch pumps; this engine also raised two rams of 7 cwt. each, for driving thevarious piles. After the water was pumped out, the excavation was carried to an averagedepth of 24 feet, the soil being alluvial and stiff clay. To excavate the basin, on theoutside the coffer-dam, which at every tide was overflowed, horse-runs were establishedto remove the soil; and what could not be moved by this means was conveyed away inballast lighters.
The foundations of the dock walls are piled, with a row of 6-incli grooved sheetingpiles in front; the other piles are 9 inches and those under the counterforts 8 inches indiameter. To drive them, a ringing engine, with a ram of 4 cwt. worked by fifteen orsixteen men, was employed. On the heads of the piles were bolted longitudinal sleepers ofhalf timber; and the sheeting piles were securely spiked to an inner waling of the samescantling. Over the sleepers was laid a transverse covering of 4-inch plank, on which wascommenced the wall. The piles were of Norway and the other timber Memel. The dockwalls were built of brick made out of the excavated clay, and where the bottom of thefenders terminate is a course of stone, 15 inches thick, passing entirely through the wall ;and between the tides are worked three other courses, all of Barnsley stone. The whole iscoped with stone from the same quarries, 15 inches thick, and 4 feet in width, the jointsbeing secured by square dowels. Warmsworth blue lime and sharp fresh water sand wereused for the mortar, the lime being previously ground dry, and afterwards mixed, and usedhot.
The oak fenders to protect this wall are 12 inches square, and project from the brickwork8 inches, the rest being sunk into the brickwork. At their feet they are dovetailed intostone corbels, and at the top they are secured by oak ties and wrought-iron fastenings.The two rows of horizontal fenders are 7 inches square, tenoned into the upright ones; andpieces arc laid under and above them, of an angular shape, to prevent vessels catching asthe tide rises or falls.
The entrance lock within the gates is in length 158 feet, its top width 42 feet, and itsheight above the pointing sills SI feet. The average depth of water at high waterspring tides is 26 feet, and at neaps 20. The foundations are built upon four rows ofbearing piles, with two others under the counterforts. These piles are from 15 to 20 feetlong, and on the heads is securely bolted sleepers of half timber, laid longitudinally. Theseare again crossed by others of the same scantling, laid on edge, and the interval coveredwith 4-inch close planking; the spaces between are filled up with solid brickwork, on whichis constructed the inverted arches and the side walls.
Across the platform are five row's of 6-inch grooved sheeting piles, from 15 to 20 feet inlength ; the bearing piles are distant about 3 or 4 feet eacli way ; on these lay longitudinalsleepers, 12 inches square, with tw’o courses of transverse sleepers close together, for 13 feetin length, from the main sill, on which the pointing sills are bolted. The other part of theplatform is covered with 6-inch close elm plank, into which the cast-iron segments in whichthe gates traverse are sunk. At the tail of the lock is an apron, about 50 feet in length,covered with 4-inch plank ; this is spiked to the transverse sills, which are bolted to the headsof the bearing piles; the outer end is protected by a row of 6-inch grooved sheeting piles.Norway timber was used for the piles, the planking is of Dantzic, and the pointing andmain sills arc of English oak.
'Hie side walls have six counterforts on each side, each 6 feet square; the walls are inwidth at the top 6 feet 9 inches, and are built of brick, faced with stone, from Bramley Fall.The hollow quoins are of stone from Dundee, and for some length a part of the wing-wallsare faced with the same material. A Bramley Fall stone coping, 13 inches thick, and4 feet wide, terminates the wall.
The lock gates are in height above the pointing sills 31 feet 4 inches, and in breadth25 feet 6 inches, measured on the curve; they camber 14] inches. At the head they arc
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