It was but the work of a moment for the crew to "dog down" the doors of that compartment to segregate the damage and prevent the flooding of other compartments. But even then, the Y-3 was in a bad way, and all on board realized it. "I guess we are gone this time," said Frank quietly to Jack. "Looks like it," was Jack's cool reply. "However, while there is life there is hope." Captain Nicholson noticed the look of anxiety on the lads' faces. "Don't you worry," he said cheerily. "We'll get out of here yet." But now the deadliest foe of the submarine was at work--chlorine gas. The action of the salt water on the sulphuric acid of the battery cells was generating it with fatal quickness. Already the boys could feel a deadly burning sensation in their throats and noses. Fifteen minutes of that atmosphere would have left all on board the submarine gasping and stifling sixty feet below the fresh air that meant life. There was but one thing to do--come to the surface and run for it in the face of the fort. Captain Nicholson realized that it would be the end if the upper exhaust of No. 3 cylinder failed now, for with the electric engines gone, running on the surface with the Diesels was the only hope. He acted on the instant. The submarine rose rapidly to the surface, and when well awash, the engines were started at full speed. The hatches were opened and the ventilating fans started, blowing out the gases and letting in the cold, damp air. All on board drew a breath of this invigorating air, and then Captain Nicholson turned his attention to escaping from beneath the big guns of the fort. From his place in the conning tower he cold plainly see the activity of the fort when the lookout made out the submarine. Now the two lads, at a sign from the commander, joined him. Glancing in the direction he pointed, they made out the fighting tops of the first two cruisers, victims of the submarine's daring raid, just reaching out of the water. The third cruiser was afloat, but from her heavy list to starboard, it was plain that she was badly damaged and sinking fast. The fort was getting the range now, and shells fell all around the Y-3. One struck the water nearby, hurling water over the conning tower and drenching the three who stood there. "Well," said Captain Nicholson, "they may get us, but we got three of them." "And there is some satisfaction in that, anyhow," said Frank. "You bet there is," Jack agreed. The submarine was halfway across the bar, and had not been hit, and every instant meant that much more chance for life. The helmsman stuck nobly to his post, head down, and without a look at the fort. The submarine shook and trembled with the vibrations of the hard-pushed engines, straining to get the submarine to deep water.