"Well, I suppose I must keep them," said Manners, "and I will, for this is about the finish up of our games, lads, for this year." He spoke unconsciously. It was; for as soon as the trio had passed from the dam on their way to the first zig-zag, from out of the darkness at one end of the dam the strange, weird noise began again. It was as if heavy blows were being given upon some great iron tool. Now and then they would cease, but only to go on again for quite two hours, till all at once a fresh sound arose--a peculiar, whispering gurgle, which gradually gathered force, to go on increasing through the night; but not another blow was heard to fall. CHAPTER EIGHTEEN. DANGER. Will returned to the Mill House that night rather later than he should have been, after a long chat with the artist, and the first thing he learned was that his father had gone to bed with a bad headache. It was his own time, too, and he hurried up to his bedroom, when, like a flash, came the recollection of the strange sounds he had heard. It was too late to go out again, so he opened the window and leaned there, listening; but from that position he could hear the roar of many waters--nothing more. As a rule, Will's habit was to bang his head down on the pillow and draw one very deep, long, restful breath, as he stretched himself at full length, and the next moment he was asleep. Somehow, on this particular night, when he went through his customary movements, the result was that he was more wide-awake than ever. Then for quite two hours he twisted, turned, stretched himself, yawned, got out of bed and drank cold water, bathed his face, walked up and down, tried to count a hundred forwards, then backwards, counting sheep going through a gap, did everything he could think of, and even thought of standing upon his head to see if that would do any good; but sleep would not come. "Am I going to be ill?" he asked himself, and while he was waiting for the answer he dropped off soundly. But for no pleasant rest, for it was into nightmare-like dreams of some great trouble. While he was trying to sleep, all recollection of the mysterious sounds was in abeyance; but they attacked him again in his dreams, with this peculiarity, that he seemed to know now exactly where they were. He was able to locate them precisely. There they were-- hammer, hammer, hammer, throb, throb, throb, till it was almost maddening. He tried to escape from them; he longed to get away; but there they were in the deep darkness, hemmed in by the deep booming chorus of the falling waters--the only part of his dreams that was real. For during the whole night, through the sluices, along the chute, and over the wheel, the waters continued their course, keeping down the overburdened pool to the same level, for once more heavy rains in the hills rushed along the stream to augment the supply.