"The fortune of war, you know," said Frank, with some sarcasm. "You heard Captain Von Cromp say he wouldn't blame us for anything we might do. Besides, they didn't give the poor fellows on that British battleship any warning, did they?" "No," said Jack, "but--" "Well, there are no buts here. You climb overboard and get ready to dive. When this bullet goes through that little plaything there will be an explosion that will kick up considerable excitement hereabouts. That's why I asked you if you couldn't get a rifle. We could have gone a little farther away then." "Now see here," said Jack. "I guess those fellows have it coming to them. They don't deserve any better than they will get. As you say, 'the fortune of war.' I'm not kicking about that. What I want to know is if you can hit that thing." "Hit it? Of course I can hit it. You dive when I say the word, and when you come up, if you do, come up, I'll guarantee you won't see any submarine." "But how about you?" demanded Jack. "If I dive before you fire, how are you going to get away before the explosion?" "I don't calculate I'll get away before it, but I'll be in the water the minute I fire. I won't wait to see whether I hit it or not. However, I'll drop the revolver in the boat, so in case I miss the first time, it will be dry enough to use again." "But--" began Jack. Frank stood up in the boat and pointed the revolver directly at the submarine. "No more words," he said quietly. "Are you ready?" Jack lowered himself over the edge of the boat, still holding to it with his hands. "Yes, I'm ready," he said, "but--" "Then dive!" cried Frank and pulled the trigger. With a single movement he dropped the revolver into the bottom of the boat, and plunged deep into the sea himself. CHAPTER VII OFF ON A LONG CRUISE At the very instant the lad disappeared beneath the water there was a flash of fire above the submarine, followed by a violent explosion-fearful, terrific. The upper work of X-9 was blown high into the air and came down in splinters, scattered to the four winds of heaven. The deck was rent and open up with a great, yawning scam, through which the ocean rushed, driving the craft below the waves as though it had been drawn down by some mighty whirlpool. A minute later, where had been one of Germany's most terrible fighters, there was only a seething flood of water covered with floating wreckage. The force of the explosion sent the water spouting high in the air like giant gushers. The sea boiled and lashed out angrily at what was left of the German craft. Not a living figure was to be seen upon the wreckage. The deadly melinite had done its work. Beneath the waters of the North Sea, where Frank and Jack had sought what shelter they could, the water tossed them about at will, in spite of their frantic efforts to hold themselves steady and remain below the surface.