The crags above them grew more accessible presently, and they scrambled up, slipping and clambering until they found themselves on a jutting rock with a wide flat surface, which, bathed in sunshine, invited them to stop and rest. Loose fragments of rock lay about the flat top, and Wally perched on one, but rose hastily. “That thing wriggled under me,” he said, “It’s just on the balance: I believe I could push it over.” “‘That Master Wally have the mischieviousness of ten boys,’ as Brownie used to say,” Jim remarked, lazily. “Sit down, and don’t play tricks with the landscape.” “It would be considerably like hard work, so I don’t think I will,” said Wally, sitting down on another fragment. “This old table of a rock wants tidying up, I think—did you ever see so many loose chunks scattered about?” “I expect a bit of the cliff fell on it from above, and flew into bits,” said Jim. “Anyhow, it’s warm and jolly. What’s that?” Something tinkled on the rock, and Wally uttered a sharp exclamation of annoyance. “Botheration! That’s my knife.” “Hard luck!” said Jim, looking at a cleft in the surface, down which the knife had vanished. “Never mind; I’ve got two with me, and you can have one.” “Thanks, but I don’t want to lose that fellow,” Wally said, vexedly. “It’s that extra-special knife Norah gave me when I was going out—the big one she called ‘the lethal weapon.’ It’s full of all sorts of dodges. I’d sooner lose a lot of odd things than that knife.” He lay flat, and put his eye to the cleft in the rock, peering downwards. “Afraid it’s gone for good, old man,” Jim said. “It’s hard luck—but Norah will understand. She’ll probably jump at the chance of giving you another.” “I want this one,” said Wally, his voice slightly muffled. He peered harder. “I say, Jim, I can see daylight down here.” “I don’t see how you can,” Jim said, leaning over in his turn. “This old rock seems pretty solid. Let’s look.” He applied his eye to the cleft, in his turn. “Well, there is light,” he said presently, sitting up. “I wonder if there’s some opening below, Wal?” “Don’t know, but I’m going to see,” Wally answered. He swung himself over the edge of the flat rock and climbed down, followed by his chum. They hunted about the great pile, seeking for some opening that might explain the glimmer of daylight that had greeted them above. On one side of the mass was the long stretch of rock from which they had first climbed up; but on the other they found smooth hard sand, only lately under water. There were openings here and there among the boulders, but they led to nothing, and had no communication with the upper air; they explored them in turn, but found no solution of the problem. Then, as Wally was backing out on hands and knees from one of these false scents, he heard a low whistle from Jim, and hurried round a boulder, to find him regarding what looked like a slit, about three feet high, between two masses of rock.