Jack Villiers had indeed made good progress as a diver. Constitutionally fitted, and possessing a steady nerve, he soon mastered the relatively-simple "gadgets" that made the self-contained diving-dress admittedly superior to that of the older type, in which the diver is hampered by life-line and air-tube. In a case of emergency the diver could blow himself to the surface by liberating a quantity of compressed air from a strong metal cylinder strapped immediately beneath the air-reservoir. The compressed air would then distend the outer fabric of the diving-suit without interfering with the wearer's breathing, with the result that the man would rise to the surface, his leaden sinkers notwithstanding. Accordingly, upon the next descent to the wreck Swaine did not go alone. Close on his heels followed Villiers, keeping a firm hold on the rope that led from the shore to the hull of the _Fusi Yama_. With little difficulty the two divers found themselves outside the strong-room door. The space between decks, lighted by the electric submarine-lamp, was shorn of most of its uncanniness by the powerful rays, but a number of fish, attracted by the glare, were swimming to and fro, sometimes butting blindly against the glass fronts of the men's helmets. Villiers was thankful that none of the fish was of a dangerous variety. They looked hideous enough, magnified by the water. There were some with formidable-looking spines, others resembling skate with ferocious, underhung jaws, some that looked like conger-eels, and one with a razor-backed body, who persisted in rubbing against Villier's bare hands until Jack drew a knife and settled it with the awkward customer. But, he was thankful to observe, sharks, sword-fish, and cuttle-fish were not in evidence. Both men set to work first to clear away the imprisoned and floating debris. Broken deck-chairs, life-belts with rotten canvas coverings, wooden buckets, and other articles that still retained their buoyancy were dragged to the companion-hatchway and liberated. This done, the doors were drawn together and lashed, leaving room for the electric-light cable leads to pass through the aperture. By so doing the divers had rendered themselves secure from roaming tigers of the deep. The steel bar on the door of the strong-room was a formidable affair. Even by the aid of the electric drills, the metal was only cut through to the depth of an inch when Swaine gave the signal to knock off and return to the beach. One hour and twenty minutes had elapsed, and another forty minutes represented the total period during which a man could remain submerged before his air-supply became impure. "Slow progress," reported Swaine, on their return. "With luck we ought to cut through that jolly old bar in a couple of hours. How did you like the job, Jack?" "Not so dusty," replied Villiers guardedly.