They came quickly on deck, and watched the strange light, which now and then disappeared, and then again became visible. It now shone bright, and then faint, and an uncertain glimmer beneath it showed that it hovered over the water as well as over the marsh. "There is no such thing as _ignis fatuus_ nowadays," said Jimmy, "so what can it be?" "I vote we go and see," said Frank. "You will only get bogged if you do. It is dangerous enough to walk on the marsh in the daylight, and almost impossible by night." "It strikes me there is a narrow channel, or dyke, leading from the river, which may lead to where that light is. I saw a line of water about twenty yards off. We passed it as we were about to anchor. Let us take the boat and go up it, if you wish to see what it is," said Jimmy. His suggestion was approved of, and they dressed and stepped into the punt, and after a little while they found the dyke and pushed their way along it. They moved cautiously and with little noise, and at last emerged upon a small open piece of water, and as they did so, the light gleamed for a moment and went out. They peered eagerly through the gloom, but could see nothing. All was silent and still, and very uncanny. "It is no good staying here," said Frank; "let us go back and try to sleep, or we shall not be fit to be seen to-morrow when we meet the others at Wroxham." So they rowed back, wondering what the cause of the light had been. They tumbled into their berths again and got just an hour's broken sleep before the dawn effectually aroused them. It was very early, but they had no choice but to rise and get something to eat. The morning was bright and cloudless, the lark sang merrily in the sky, waterfowl swam on the quiet stretches of the river in peaceful security, the freshness and charm which always accompanies the early dawn of day in the country had its natural effect upon them; and their spirits, which had been somewhat depressed by the uncomfortable night which they had passed, rose again to their natural height. Dick now suggested that they should again explore the windings of the creek, and try to find out the cause of the mysterious light which had so puzzled them the night before. They accordingly rowed up the lane of water as they had done the previous night, until they came to the piece of open water. Just as they were about to emerge from the narrow opening in the belt of reeds which surrounded it, Frank checked the motion of the boat by clutching hold of the reeds, and warned his companions to be silent. Looking in the direction in which he pointed, they saw the most curious bird they had ever seen, or were ever likely to see. On a little hillock on the edge of the reeds was a bird with a body like a thrush, but with long legs. It had a long beak, staring eyes, brown tufts of feathers on each side of its head, and a large flesh-coloured ruff of feathers round its neck. "I know what that is; it is a ruff," said Jimmy.