Chiefly concerned with the dam of rock, Grenville secured his raft with boyish impatience and carried his torch ashore. A moment afterwards he walked through the breach in the erstwhile solid ledge, and could readily imagine the roar with which the water, formerly behind the barrier, had tumbled torrentially into the swirling tide. There was still a tiny trickle flowing down the channel made by the bomb. The basin formed by the bottom of the cavern was still exceedingly damp, and here and there it retained a shallow pool of water too low for the gateway to drain. He walked about freely, pausing here and there to hold his torch aloft and measure the cave's dimensions by means of the light from both the open entrance and his blazing, yellow flame. He was struck, in gazing at the wall he had broken near the cavern's mouth, with the size of one of the fissures there, where the blast had wrought its havoc. So black and significant appeared this new-formed aperture that, although a certain eagerness to proceed forthwith to the treasure niche was upon him, he returned at once to investigate the hole. What he found upon his first superficial examination was merely a crevice, half as wide as his body, where a plinth of rock had been split from the mass and dropped towards the breach in the dam. Into this crevice he thrust his torch, and was instantly interested to note that its flame blew decidedly from him, in a draught of air that was flowing unmistakably upward. Moreover, on lifting himself sufficiently high to look about in the dimly lighted space, he became convinced that either a second chamber or a passage like a hall existed just back of the principal cavern, from which it was partitioned by the wall. He planted his torch between some loosened fragments and shook at the piece that blocked this auxiliary cave. He thought he could topple the slab out forwards on the ledge. But, when he rocked it with his customary vigor, it fell abruptly backwards and disappeared in the gloom. The hole he had thus created was quite large enough to admit him, squeezing in sideways. He promptly entered with his torch, finding the foothold rough and insecure. The chamber itself was small and low. He could readily touch the ceiling. Ahead it apparently ended in a wall, with a gaping crack. On moving there, however, he found, to his surprise, an angular turn, still wide enough to admit of easy passage. The way under foot was slightly upward. It was pitted rock, but surprisingly free from broken fragments. Persuaded at once that no other man had ever discovered this channel-like chamber in the tufa, and that therefore no treasure would be found concealed in its depths, Grenville continued onward with unabated interest, curious to see how far the passage might extend.