They drew back from the eel-trap, Will leading the way, and made for a door in the huge shed, where the lantern was carefully extinguished and put on a ledge, before they stepped out into the dark night, the closing of the door behind them shutting in a good deal of the hollow roar, with its whispering echoes. That which they listened to now was more splash, rush and hurry, as the wheel turned at greater than its usual speed, and the overladen dam relieved itself of its contents. Still there was too much noise for easy converse, and they tramped on, Will with the intention of climbing to one of the narrow paths that led in the direction of the upper stream. They were just on a level with the top of the stone dam, when Will stopped short. The spot he had chosen for his halt was dark as pitch, for a clump of bushes overhung the way. "What's the matter?" said Josh, who came next. "Be quiet," replied Will. "Anything wrong?" asked the artist, for they blocked his way. "N-no," replied Will, dubiously; "only thought I heard something." "Thought you heard something!" said Manners. "There's not much think about it. My ears seem stuffed so full of sounds that I can hardly hear myself speak. The rushing water and its echoes from up above seem to fill the air. What did you think you heard?" "That's what I don't know," said Will, thoughtfully, with his lips close to the speaker's ear; "and I can't hear it at all now. It was a dull, thumping sort of noise." "Echo," said Josh. "The wheel's going so much faster round than usual." "N-n-no," said Will; "it wasn't like that. I wish I could hear it again." "What for?" said Josh. "What was the matter? Here, I say, which way shall we go? I know: let's go and see if any of the old owls are out beating the ivy for birds." "There," cried Will, "that's it! You can hear it now! Listen!" All stood perfectly still for a few moments. "Water, water everywhere, and far too much to drink," said Manners, spoiling a quotation. "I can't hear anything else." "Oh, Mr Manners! Why, there it is, quite plain. You can hear it, can't you, Josh?" "Thumpety, thumpety, thump, thump, thump!" said Josh. "Sounds like somebody beating a bit of carpet indoors. Why, it's only echoes." "Pooh! What could make echoes like that?" "The great axle of the wheel worked a little loose in its bearings through the weight of the water." "Nonsense! Can't be that." "All right! What is it, then?" "Don't know, don't care. It's a nocturnal noise, isn't it, Mr Manners?" "Well, it's a noise," said the artist, "as if someone was hammering with a wooden mallet. I heard it quite plainly just now, and it seemed to come from below there, out of the darkness down at the bottom of the dam." "Oh, no," cried Josh, "it was from right up yonder, ever so high." "No, no," said Will; "it seemed to me to come from just opposite where we are standing now." "Echo," said the artist, laconically.