"That is an obvious statement," rejoined his fellow-worker. "We certainly weren't working in a dust-laden atmosphere. By Jove, I am hungry! What's going, Pete?" "Taro and pork-pie, sah," replied the cook, whereupon all the others laughed, for that sort of pie had become part of the daily routine. "Keen on carrying on, Jack?" inquired Swaine, when, having partaken of a substantial meal, all hands were resting and enjoying a smoke. "Rather," replied Villiers emphatically. "I'm anxious to see the other side of that strong-room door." "Come on, then," continued Swaine, knocking out his pipe on the heel of his boot. "Now, then, fall in, the divers' attendants. There's no need to stand there hanging on to the slack. Slap it about." With increased confidence Villiers plunged into the water, following his chum. At a pre-arranged signal the electric submarine-lamp was switched on and the companion-doors closed. Alternately holding the electric drill, the two divers resumed their attack upon the steel bar, until Swaine gave the signal to desist. Then pointing to a heavy sledge hammer, he motioned to Villiers to give the _coup de grâce_. It looked a simple task to break the almost severed bar. The hammer, weighing fourteen pounds in air, seemed ridiculously light, but when Villiers tried to swing it, the result surprised him. He had not calculated the resistance of the water. At the third attempt Jack laid the hammer down in disgust, then picking up a crow-bar he applied the wedge-shaped end to the bar and bore down with all his weight, planting one leaden-soled boot against the door to give greater leverage. The steel bar gave. Villiers found himself deposited gently on his back. Agreeably surprised that he hadn't fallen violently, he realized that the resistance of the water that had rendered the hammer-blows almost useless had also let him down softly. It took him some moments to regain a vertical position. He could see his companion grinning at him through the plate-glass front of his helmet. Then almost the next instant he became aware that he could not keep contact with the floor but was rising through the water. Inadvertently, in his struggles he had opened the release-valve to the compressed-air reservoir, and but for the intervening roof he would have been well on his way to the surface. It had taken place so quickly that Swaine had no chance to come to the luckless diver's assistance, while most of the compressed air had found its way into Villier's diving-dress. By the time Swaine succeeded in closing the valve Jack was pinned pretty firmly against the ceiling. Vainly he strove, by pushing against the roof, to force himself down. A mild panic seized him. He struggled so violently that he rasped the skin from the knuckles of his bare hands.