"Very true." He pulled out his watch with his left hand, and held it before his eyes so that he could observe the time without losing sight of me for even an instant. "I doubted that I could secure your willing cooperation; therefore, I am commanding it.

"You see, there are certain instruments and pieces of equipment that I should like to take back to my laboratory with me. Perhaps I would be able to reproduce them without models, but with the models my task will be much easier.

"The question remaining is a simple one: will you give the proper orders to have this equipment removed to the spot where you first saw me, or shall I be obliged to return to my own era without this equipment--leaving behind me a dead commander of the Special Patrol Service, and any other who may try to stop me?"

I tried to keep cool under the lash of his mocking voice. I have never been adept at holding my temper when I should, but somehow I managed it this time. Frowning, I kept him waiting for a reply, utilizing the time to do what was perhaps the hardest, fastest thinking of my life.

There wasn't a particle of doubt in my mind regarding his ability to make good his threat, nor his readiness to do so. I caught the faint glimmering of an idea and fenced with it eagerly.

"How are you going to go back to your own period--your own era?" I asked him. "You told me, I believe, that it was impossible to move backward in time."

"That's not answering my question," he said, leering. "Don't think you're fooling me! But I'll tell you, just the same. I can go back to my own era: that is, back to my own actual existence. I shall return just two hours after I leave; I could not go back farther than that, and it's not necessary that I do so. I can go back only because I came from that present; I am not really of this future at all. I go back from whence I came."

"But," I objected, thinking of something I had read in the clipping he had showed me, "you're not going back to your own era. You cannot. If you returned, you would put your project into execution, and history does not record that activity." I saw from the sudden narrowing of his abnormally long eyes that I had caught his interest, and I pressed my advantage hastily. "Remember that all the history of your time is written, Harbauer. It is in the books of Earth's history, with which every child of this age, into which you have thrust yourself, is familiar. And those histories do not record the domination of the world by yourself. So--you are confronted by an impossibility!"

My reasoning, now, sounds specious, and yet it was a line of thought which could not be waved aside. I saw Harbauer's black brows knit together, and mounting anger darken his face. I do not know, but I believe I was never nearer death than I was at that instant.

"Fool!" he cried. "Idiot! Imbecile! Do you think you can confuse me, turn me from my purpose, with words? Do you? Do you believe me to be a child, or a weakling? I tell you, I have planned this thing to the last detail. If I had not found what I sought on this first trip, I would have taken another, a dozen, a score, until I found the information I sought. The last six years of my life I have worked day and night to this end; your histories and your words--"

My plan had worked. The man was beside himself with insane anger. And in his rage he forgot, for an instant, that he was my captor.

Taking a desperate chance, I launched myself at his legs. His weapon roared over my head, just as I struck. I felt the hot gas from the thing beat against my neck; I caught the reeking scent of the smoke.

Then we were both on the floor, and locked in a mad embrace.

Harbauer was a smaller man than myself, but he had the amazing strength of a Zenian. He fought viciously, using every ounce of his strength against me, striving to bring his weapon into use, hammering my head upon the floor, racking my body mercilessly, grunting, cursing, mumbling constantly as he did so.

But I was in better trim than Harbauer. I have never seen a laboratory man who could stand the strain of prolonged physical exertion. Bending over test-tubes and meters is no life for a man. At grips with him, I was in my own element, and he was out of his. I let him wear himself out, exerting myself as little as possible, confining my efforts to keeping his weapon where he could not use it.

I felt him weakening at last. His breath was coming in great sobs, and his long eyes started from their sockets with the strained effort he was putting forth. And then, with a single mighty effort, I knocked the pistol from his hand, so that it slid across the floor and brought up with a crash against a wall of the room.

"Now!" I said, and turned on him.

He knew, at that moment when I put forth my strength, that I had been playing with him. I read the shock of sudden fear in his eyes. My right arm went about him in a deadly hold; I had him in a grip that paralyzed him. Grimly, I jerked him to his feet, and he stood there trembling with weakness, his shoulders heaving as his breath came and went between his teeth.

"You realize, of course, that you're not going back?" I said quietly.

"Back?" Half dazed, he stared at me through the quivering lids of his peculiar eyes. "What do you mean?"

"I mean that you're not going back to your own era. You have come to us, uninvited, and--you're going to stay here."

"No!" he shouted, and struggled so desperately to free himself that I was hard put to it to hold him, without tightening my grip sufficiently to dislocate his shoulders. "You wouldn't do that! I must return; I must prove to them--"

"That's exactly what must not happen, and what shall not happen," I interrupted. "And what will not happen. You are in a strange predicament, Harbauer; it is already written that you do not return.

Can't you see that, man? If it were to be that you left this age and returned to your own, you would make known your discovery. History would record it. And history does not record it. You are struggling, not against me, but against--against a fate that has been sealed all these centuries."

When I had finished, he stared at me as though hypnotized, motionless and limp in my grasp. Then, suddenly, he began to shake and I saw such depths of terror and horror in his eyes as I hope never to see again.

Mechanically, he glanced down at his watch, lifting his wrist into his line of vision as slowly and ponderously as though it bore a great weight.

"Two ... two minutes," he whispered huskily. "Then the automatic switch will close, back in my laboratory. If I am not standing where ... where you found me ... between the disc and the grid of my time machine, where the reversed energy can reach me, to ... to take me back ... G.o.d!"

He sagged in my arms and dropped to his knees, sobbing.

"And yet ... what you say is true. It is already written that I did not return." His sobs cut harshly through the silence of the room.

Pitying his despair, I reached down to give him a sympathetic pat on the shoulder. It is a terrible thing to see a man break down as Harbauer had done.

As he felt my grip on him relax, he suddenly shot his fist into the pit of my stomach, and leaped to his feet. Groaning, I doubled up, weak and nerveless, for the instant, from the vicious, unexpected blow.

"Ah!" shrieked Harbauer. "You soft-hearted fool!" He struck me in the face, sending me crashing to the floor, and s.n.a.t.c.hed up his pistol.

"I'm going, now," he shouted. "Going! What do I care for your records and your histories? They are not yet written; if they were I'd change them." He bent over me and s.n.a.t.c.hed from my hand the ring of keys, one of which I had used to unlock the door of the navigating room. I tried to grip him around the legs, but he tore himself loose, laughing insanely in a high-pitched, cackling sound that seemed hardly human.

"Farewell!" he called mockingly from the doorway. Then the door slammed, and as I staggered to my feet, I heard the lock click.

I must have acted then by instinct or inspiration. There was no time to think. It would take him not more than three or four seconds to make his way to the exit, stroll by the guard to the spot where we had found him, and--disappear. By the time I could arouse the crew, and have my orders executed, his time would be up, and--unless the whole affair were some terrible nightmare--he would go hurtling back through time to his own era, armed with a devastating knowledge.

There was only one possible means of preventing his escape in time. I ran across the room to the emergency operating controls, cut in the atomic generators with one hand and pulled the Vertical-Ascent lever to Full Power.

There was a sudden shriek of air, and my legs almost thrust themselves through my body. Quickly, I pushed the lever back until, with my eye on the altimeter, I held the _Ertak_ at her attained height--something over a mile, as I recall it. Then I pressed the General Attention signal, and s.n.a.t.c.hed up the microphone.

Less than a minute later Correy and Hendricks, fellow officers, were in the room and besieging me with solicitous questions.

It had been my idea, of course, to keep Harbauer from leaving the ship, but it was not so destined.

Shiro, the sentry on duty outside the _Ertak_, was the only witness to Harbauer's fate.

"I was walking my post, sir," he reported, "watching the sun come up, when suddenly I heard the sound of running feet inside the ship. I turned towards the entrance and drew my pistol, to be in readiness. I saw the stranger we had taken into the ship appear at the exit, which, as you know, was open.

"Just as I opened my mouth to command him to halt, the _Ertak_ shot up from the ground at terrific speed. The stranger had been about to leap upon me; indeed, he had discharged some sort of weapon at me, for I heard a crash of sound, and a missile of some kind, as you know, pa.s.sed through my left arm.

"As the ship left the ground, he tried to draw back, but he was off balance, and the inertia of his body momentarily incapacitated him, I think. He slipped, clutched at the gangway across the threads which seal the exit, and then, at a height I estimate to be around five hundred feet, he fell. The _Ertak_ shot on up until it was lost to sight, and the stranger crashed to the ground a few feet from where I was standing--on almost exactly the spot where we first saw him, sir.

"And now, sir, comes the part I guess you'll find hard to believe.

When he struck the ground, he was smashed flat; he died instantly. I started to run toward him, and then--and then I stopped. My eyes had not left the spot for a moment, sir, but he--his body, that is--suddenly disappeared. That's the truth, sir, for I saw it with my own eyes. There wasn't a sign of him left."