HISTORY OF ENGINEERING.
Book I.
826
"built into the brickwork, and secured by oak brackets on each side, as well as by strongiron bolts.
The walls arc built upon longitudinal sleepers, 12 inches by 6, laid flat, and trenailodon to pile heads ; across these are laid 3-inch planks, all of fir timber.
The piling having given way, and the walls bulged out in some places, a great portionwas obliged to be rebuilt.
Lock and basin. The original lock, 36 feet 6 inches in width, 24 feet € inches deep,and 200 feet in length, was built upon a wooden floor; 4-inch planks were laid upontransverse and longitudinal joists, bedded on 1245 bearing piles, 12 feet in length : acrossthe lock were six rows of grooved sheet piling, 14 feet in length. The walls, constructedof brick, were faced with Mexborough stone, and the hollow quoins and coping were ofBramley Fall, all set in puzzolana.
The basin was constructed in the same manner, and was in length 212 feet, and inwidth 80 feet.
The entrance lock and basin, in the year 1814, was entirely rebuilt, under the directionof Mr. Itennic, the old one having become decayed. After the water was drawn out ofthe dock to within 4 or 5 feet of the bottom, a coffer-dam was made at the outer endof the basin, next the harbour, and a dam of clay on the side next the dock, and the lockand basin walls were removed, when the piles, sleepers, and planks were found perfectlysound, although in many places the foundations had considerably gone down.
The new lock is 120 feet 9 inches in length, within the gates, 38 feet wide at the top, and24 feet 6 inches high, above the sills.
The inverted arch is brick laid in puzzolana, as well as the side walls, which werefaced with Bramley Fall stone; the lowest course was all headers, 4 feet in length, and18 inches in thickness. The hollow quoins are of Rotherham stone, and the coping ofcoarse sandstone from Bramley Fall, 15 inches in thickness, and 4 feet in width.
The gates arc constructed of English oak, except the planking, which is of fir, 2\ inchesin thickness. They arp each 23 feet wide, 24 feet 3 inches high above the pointing sill,16 inches thick at the heel, and 14£ inches at the head. There are 10 bars or ribs, slightlycurved, tenoned into the heel-posts, and secured by iron straps and screw bolts.
The sluices are of cast-iron, 2 feet 6 inches square in the clear, and are worked by awrought-iron screw and brass nut, with bevel gear at top.
To move the gates, at the side of the lock, is placed machinery which turns a cast-ironroller, round which is a revolving chain made of |-inch iron; these chains are fixed from2 to 4 feet above the bottom sill for shutting, and 7 feet for opening the gates; to assist thelatter operation, there is a counterbalance weight, which prevents the chains from runningoff the roller.
In front of the lock walls, at about 10 feet above the sills, is placed one horizontaland two vertical rollers, with another large horizontal one, at the foot of each wall, aroundwhich the chain turns whilst working the gates.
The heel-post has a cast-iron socket at the bottom, SJ inches in diameter, and 1| deep:this turns on a cast-iron pivot securely fixed on the bottom.
The brass friction roller, which moves on a segment of cast-iron, is 10 inches in diameter,and 4 inches in length, fitted into a cast-iron box or frame near the meeting post; tothis is attached a wrought-iron regulating rod, which reaches to the top of the gate, toadjust the roller.
The bridge over the lock, of cast-iron, is 15 feet in width, the road for carriages being 7feet 6, and the entire length 81 feet. It is formed of six ribs, inch in thickness inthe middle, and 3 inches thick at the flanch; they are 9 inches deep where they meet inthe middle, and increase a little towards the sides. The bridge turns on a east-iron shaft,8 inches square, with four round bearings, working in plummer blocks, fixed in cast-ironcarriages bolted firmly into the masonry.
To open this balance bridge, a lever is applied to lift a cast-iron flap, which turns on anaxis 4£ inches square: when this flap is lifted, the bridge rises, and the flap forms abarrier against passengers, and when the bridge is again lowered, it forms part of theroadway.
The bridge is covered with oak plank, S inches in thickness, bolted to the iron ribs, andwhere the wheels of the carriages pass it is lined with 1£ inch elm. The footways are alsolined in the same way, and stand up about 5 inches above the road on each side, guardedby a cast-iron curb, and wrought-iron bars and chains.
As this bridge ascends, the outer end descends into a cavity, prepared for the purpose,and one man can raise or lower each portion in half a minute; its weight, exclusive of thetimber, is about 80 tons.
Basin of entrance is 213 feet in length, 80 feet 6 inches in width at the top, and 71 feetat the bottom. It is cased with brick, and coped with stone from Bramley Fall; 14 feetfrom the bottom is a bond course of the same stone, passing through the whole thickness.