140
TIDAL LAND RECLAMATION
during which a number of futile attempts had been made to shut out the water. The total length of the breach was nearly 700 feet, and the water impounded was something like 30,000,000 cubic feet. As the tide fell the water poured in a cataract through the central gorge of the breach, which acted as a weir, so that the bed of the river was progressively excavated to a great depth. Owing to the long soakage of the soil over the whole area, it had become so sodden that the extent to which it could be trusted to carry weight was highly problematical. This breach was stopped after one mishap, and the methods by which the result was achieved afford a key to the solution of difficult problems of this nature. The ground in rear of the breach was intersected by a number of arterial ditches, and, owing to the scour of the floods, these converged towards the breach. By driving shuttering either in timber or steel across the line of such ditches, and dropping jute sacks filled with clay in rear of the same, the worst rush of water from the ditches was stanched. After being thus barricaded, the ditches became converted into reservoirs holding up a considerable proportion of the impounded water. The next step was to drive a timber gantry from one side of the breach to the other, the piles being so placed that they subsequently became an integral part of the design of the timber dam ultimately constructed. Sluices were driven through the walls in order to carry off as much of the superficial water as possible as the tide fell. This operation was one requiring much care, as the whole of the walls within which the inundation lay were in so tender a state that further breaches might quite easily have been produced. The main object in the operations was to constrict the orifice of the effluent water as much as consistent with safety, and then, in the course of a single tide, to drop all the guillotine shutters, thus completely closing the exit of the water, care being taken that this should be done as near low water as possible. A large number of bags of clay were also assembled on both sides of the breach, and on the shutters being lowered and made secure, a force of men was engaged in depositing these bags of clay behind the shutters to seal the surface of the bed of the breach, and prevent the blowing up of the timber framing as the head of water increased