He flashed his torch into the comers as they turned to retrace their steps. One was plainly nothing but solid wall: but in the other something caught his eye; a darker patch of shadow that was not quite like the rock. “Why, I believe there’s an opening in that corner,” he said. “It must be another cave, communicating with this one. Come and see.” The opening was only wide enough to admit one at a time, and so screened by a jutting boulder that it was almost invisible. Within was a cave very like the first one, though much larger; differing from it, too, in that the sand ended, and the floor was of fairly smooth rock, which, in the middle, held a great pool of water. This time there was no doubt that they were at the end of their subterranean journey; Jim flashed the light right round the wall, but there was no break in the solid rock, glistening with wet. “Well, that’s the finish,” Wally said. “It isn’t a wildly exciting place, except for that demoniacal echo. We’ll bring Norah and the others here and make it talk. I’d like to hear what its little efforts would be like if one gave a football yell!” “Something would break,” said Jim, suppressing a laugh. He strolled across to the pool, and turned the light on its black surface. “That is a deep and mysterious and probably, haunted water-hole and you’d better be careful,” said Wally in a sepulchral whisper. “Most likely the Bunyip lives there, and in a moment we shall see his grisly head emerge from the unfathomed depths, and then all will be over with two promising young officers of His Majesty’s Army.” He paused for breath. “Idiot!” said Jim, pleasantly. “I wonder if it’s deep. Lend me your stick, Wal.” He leaned over the pool and thrust the stick into its depths. It went in for its full length. Then came a sound which made the boys look at each other in bewilderment. “It sounds as if the Bunyip had been chucking his old tins in,” Wally said. “It’s tin, I’ll swear,” Jim answered. “And solid at that; I can’t move it.” He took off his coat, rolled his shirt-sleeve to the shoulder, and recommenced investigations. It was easy enough to feel the stick scraping on tin; beyond that, he could make out nothing, save that there was plenty of tin to scrape. Jim desisted at length, and stood pondering. “I think this is pretty queer,” he said, presently. “Wonder if we’ve stumbled on a smuggler’s cave, Wal. Look here, I’m going to paddle.” “Well, you don’t know the depth of that beastly place,” Wally said. “For all we know it may be miles deep.” “Well, can’t I swim?” Jim queried in amazement. “Yes, a little. Anyhow, I’m coming, too.” Jim laughed softly. “I thought that was it,” he said. “Look here—you stay at the edge with the light, and I’ll hold one end of the stick, and you can hang on to the other. That will make it all right. There’s no sense in out both paddling in.”