He held a heavy wrench in his hand. His features were contorted with rage, and there was that terrible light in his eyes.

He burst into a volley of profane abuse and came for me with the wrench. I stepped back and covered him with my gun. "Cut it!" I snapped. "And don't forget that now that the motor's gone haywire I don't need you any more."

At that he lowered the wrench and stood there snarling at me. "Now that you don't need me, I suppose you'll murder me. That's what I've been expecting right along; that's the best anyone could expect from scum like you."

"Don't be a fool, Perry. Get busy and do something, or I will. As long as you behave yourself, I won't interfere with the handling of the ship."

"What do you want me to do?" he demanded. "Haven't I been working all morning trying to make these repairs?"

"That's all right, but you ought to dump some water ballast now and get a little more altitude. " I had refrained from doing this myself because I had found that any independent action I took always aroused Perry's anger, and I didn't wish to irritate him; conditions were unpleasant enough at best.

"We don't have to dump any water ballast," he snapped; "that's for an emergency."

"We are facing an emergency right now."

"A college education did you a lot of good, " he sneered. "Don't you know that heat will expand the gas in the bag? The sun will keep us up."

I pointed through a window at the water billowing close beneath us. "It isn't, though."

"It's got to," he insisted. "I guess I know my physics."

I turned toward the control room. "Perhaps you do, Perry; but what we need now is altitude."

"What you going to do?"

"Let out some water ballast."

"If you do, I'll kill you!" he screamed, and at the same instant he hurled the wrench at my head.

I ducked, and it whizzed by my ear. I heard it crash into something behind me as Perry charged, his face a horrid mask of maniacal rage. I was glad that I didn't have to shoot him; it wasn't necessary now, for he was unarmed, and I have always been able to take care of myself where it was only a matter of fists and brawn.

He was sort of clawing at me as he rushed forward, as though he wanted to get hold of my jugular and tear it out, or, maybe, my heart. He was not a pretty picture. How different he looked from the Billy Perry I used to go to school with! It was as though another personality, both physical and spiritual, possessed him; and the change suggested, even in that moment of stress, the strange dual personality of that pathetic figure of Robert Louis Stevenson's imagination, Dr. Jekyll.

Of course it didn't take as long for all this to happen as I am taking in the telling; he was on me the instant after the wrench flew by my head; but before his fingers closed upon my throat I let him have a short jab to the chin. It wasn't a very hard blow (I didn't want to hit him as hard as I could; just enough to do the work), and he went down without another sound. He was out, all right.

Chapter 4 Battling a Maniac

I LEFT PERRY LYING WHERE HE HAD FALLEN AND WENT ON into the control room, where I opened a valve and let the water run from the ballast tank. Presently we commenced to rise again, and I closed the valve; then I picked up the wrench he had thrown at me. As I did so, I saw what it had hit: the instrument board. The altimeter, compass, and oil gauge were wrecked. I tell you, things looked pretty hopeless to me right then. Not that I'd been harboring any great amount of hope before, but this seemed the last blow; for even if Perry were able to patch up the engine, the loss of the compass left us in a bail fix.

Perry was out for about ten minutes. When he came to, he got up and sat on the edge of his bunk looking sort of confused. "What happened?" he asked.

"Oh, nothing," I replied; "you just tried to kill me, and I handed you the old K.O."

"I don't remember," he said. "What was it all about?"

I told him, and he shook his head.