At first the youth was inclined to drop the knife, but he managed to hold on. Then began an intensely interesting struggle between boy and fish. Dave tried his best to twist the hand around so that he might cut the fish a second time. He brought up his other hand, in an endeavor to transfer the knife, but as quick as a flash the ray of fire unloosened itself and caught both wrists. In its own way it was fighting for its mate, a prisoner in the net. Dave's two hands were now drawn tightly to his father's throat, as if the horrible monster of the deep meant to make the boy strangle his own parent! "I must get my hand free!" thought the young diver. Again he struggled, the sweat standing out on his forehead inside of his diving helmet. At last he managed to turn one wrist and got the point of the knife again into the fish's body. He cut and twisted as best he could and felt the ray of fire quiver with pain and rage. The fish could not stand the cutting and presently raised its head in order to make a new move. Exerting all of his strength, Dave made a slash at the head and cut into the light on the fish's snout. A rush of phosphorescent blood followed, and on the instant all of the light died out in the creature's body. Again Dave made a cut, striking deep into the fish, so deeply in fact that he made an ugly scratch on his father's neck. This last blow was too much for the ray of fire, and slowly it fell away and floated off, Dave did not know to where. Freed from his captor, Amos Fearless sank in a heap at the door of the diving bell. Was he dead? In frantic haste the youth pulled himself and his parent into the bell and shut the door. Then he gave a quick signal to be raised to the surface. There was no immediate answer, and a fresh alarm took possession of the young diver. "What does this mean? Why don't they pull us up?" he asked himself. Generally the life-line, as it is termed, is watched constantly, and every signal of a diver is acted upon on the instant. Were this not so, many a man of the deep would go down never to come up. A minute went by and still the signal remained unanswered. To the boy the time seemed an age. Feeling that his parent might die before being brought up, he began to empty the diving bell of water. There was a fresh-air hose attached to the bell, and as the water was forced out the air came in, until at last the bell was as dry as a hogshead that has been emptied. The moment the water was out, Dave began to work upon his diving suit. It was no easy job to get it off without assistance. Generally one diver helped the other, but he could obtain no aid from that form now lying stiff and motionless upon the floor of the diving bell. At last his arms and his head were free and he turned his attention to his parent. He unscrewed the helmet and then the rest of the old diver's suit.