As they emerged from the shelter of the tower into the rainy dusk, they were met by Fitz, who, like the other civilians in the place, had enrolled himself as a volunteer. When he first spoke, his voice was inaudible, owing to a rushing, roaring sound which filled the air. “Why, what’s this?” shouted the Colonel. “The canal, sir,” answered Fitz, as loudly. “Winlock sent me to ask you to come and look at it.” “Is it in flood? Can the reservoir have burst?” “We think the enemy have opened the sluices. The dead body of a white man was washed down just now. We saw it, though we couldn’t reach it, and some one said it was Western, who was in charge at the canal works.” The Colonel and Mr Burgrave hurried along the rampart, sheltered from the enemy’s fire by the gathering darkness, to the rear wall of the fort, the base of which was washed by the canal. The canal itself was part of the great system of irrigation-works by means of which, as the Commissioner had once complained, General Keeling had made Khemistan. A huge reservoir was constructed in the hills to receive the torrents of water which rushed down every ravine after a storm, and which, after carrying ruin and destruction in their path, ran fruitlessly to waste. By means of sluices the outflow was regulated with the minutest care, and the precious water husbanded so jealously that even in the hottest seasons it was possible to supply the canal which, with its many effluents, had converted the immediate surroundings of Alibad from a sandy waste into a garden. In view of the possible necessity of coping with an occasional rush of water, the banks were artificially raised, and the one opposite the south-west angle of the fort, where the canal took a sudden bend, had been strengthened to a considerable height with masonry, to protect the cultivated land beyond it from inundation. This change in its course largely increased the force of the current at this point. After a storm the placid canal always became a rushing torrent, on account of the accessions it received after leaving the reservoir, but none of those in the fort had ever seen it rise to the height it had reached on the present occasion. Colonel Graham uttered an exclamation of dismay when he looked out over the turbid stream, which seemed to be flung back from the opposite bank against the fort wall with even increased violence. Presently there was a lull in the storm, and by the aid of a lantern, which was lowered from the rampart, he was able to see that the current was actually scouring away the lower courses of the wall. The next moment the lantern was violently swept from the hand of the man who held the cord, as another rush of water came swirling round the tower at the angle of the wall, dashing its spray into the faces of the watchers. Every one of them felt the wall shake under the blow, and there was a murmur of uneasiness. Colonel Graham recovered himself first.