(Was it Harlan's imagination, or had a spark of alarm sprung to life in those old, tired eyes?) "I mean, can the circle break? Let me put it this way. If an unexpected blow on the head puts me out of action at a time when the memoir distinctly states I am well and active, is the whole scheme disrupted? Or suppose, for some reason, I deliberately choose not to follow the memoir. What then?"

"But what puts all this in your mind?"

"It seems a logical thought. It seems to me that by a careless or willful action, I could break the circle, and well, what? Destroy Eternity? It seems so. If it _is_ so," Harlan added composedly, "I ought to be told so that I may be careful to do nothing unfitting. Though I imagine it would take a rather unusual circ.u.mstance to drive me to such a thing."

Twissell laughed, but the laughter rang false and empty in Harlan's ear. "This is all purely academic, my boy. Nothing of this will happen since it hasn't happened. The full circle will not break."

"It might," said Harlan. "The girl of the 482nd----"

"Is safe," said Twissell. He rose impatiently. "There's no end to this kind of talk and I have quite enough of logic-chopping from the rest of the subcommittee in charge of the project. Meanwhile, I have yet to tell _you_ what I originally called you here to hear and physiotime is still pa.s.sing. Will you come with me?

Harlan was satisfied. The situation was clear and his power unmistakable. Twissell knew that Harlan could say, at will: "I will no longer have anything to do with Cooper." Twissell knew Harlan could at any moment destroy Eternity by giving Cooper significant information concerning the memoir.

Harlan had known enough to do this yesterday. Twissell had thought to overwhelm him with the knowledge of the importance of his task, but if the Computer had thought to force Harlan into line in that way, he was mistaken.

Harlan had made his threat very clear with respect to Noys's safety, and Twissell's expression as he had barked, "Is safe," showed he realized the nature of the threat.

Harlan rose and followed Twissell.

Harlan had never been in the room they now entered. It was large and looked as though walls had been knocked down for its sake. It had been entered through a narrow corridor which had been blocked off by a force-screen that did not go down until after a pause sufficient for Twissell's face to be scanned thoroughly by automatic machinery.

The largest part of the room was filled by a sphere that reached nearly to the ceiling. A door was open, showing four small steps leading to a well-lit platform within.

Voices sounded from inside and even as Harlan watched, legs appeared in the opening and descended the steps. A man emerged and another pair of legs appeared behind him. It was Sennor of the Allwhen Council and behind him was another of the group at the breakfast table.

Twissell did not look pleased at this. His voice, however, was restrained. "Is the subcommittee still here?"

"Only we two," said Sennor casually, "Rice and myself. A beautiful instrument we have here. It has the level of complexity of a s.p.a.ceship."

Rice was a paunchy man with the perplexed look of one who is accustomed to being right yet finds himself unaccountably on the losing side of an argument. He rubbed his bulbous nose and said, "Sennor's mind is running on s.p.a.ce-travel lately."

Sennor's bald head glistened in the light. "It's a neat point, Twissell," he said. "I put it to you. Is s.p.a.ce-travel a positive factor or a negative factor in the calculus of Reality?"

"The question is meaningless," said Twissell impatiently. "What type of s.p.a.ce-travel in what society under what circ.u.mstances?"

"Oh, come. Surely there's something to be said concerning s.p.a.cetravel in the abstract."

"Only that it is self-limiting, that it exhausts itself and dies out."

"Then it is useless," said Sennor with satisfaction, "and therefore it is a negative factor. My view entirely."

"If you please," said Twissell, "Cooper will be here soon. We will need the floor clear."

"By all means." Sennor hooked an arm under that of Rice and led him away. His voice declaimed clearly as they departed. "Periodically, my dear Rice, all the mental effort of mankind is concentrated on s.p.a.ce-travel, which is doomed to a frustrated end by the nature of things. I would set up the matrices except that I am certain this is obvious to you. With minds concentrated on s.p.a.ce, there is neglect of the proper development of things earthly. I am preparing a thesis now for submission to the Council recommending that Realities be changed to eliminate all s.p.a.ce-travel eras as a matter of course."

Rice's treble sounded. "But you can't be that drastic. s.p.a.ce-travel is a valuable safety-valve in some civilizations. Take Reality 54 of the 290th, which I happen to recall offhand. Now there----"

The voices cut off and Twissell said, "A strange man, Sennor. Intellectually, he's worth two of any of the rest of us, but his worth is lost in leapfrog enthusiasms."

Harlan said, "Do you suppose he can be right? About s.p.a.ce-travel, I mean."

"I doubt it. We'd have a better chance of judging if Sennor would actually submit the thesis he mentioned. But he won't. He'll have a new enthusiasm before he's finished and drop the old. But never mind----" He brought the flat of his hand against the sphere so that it rang resoundingly, then brought his hand back so that he could remove a cigarette from his lip. He said, "Can you guess what this is, Technician?"

"Harlan said, "It looks like an outsize kettle with a top."

"Exactly. You're right. You've got it. Come on inside."

Harlan followed Twissell into the sphere. It was large enough to hold four or five men, but the interior was absolutely featureless. The floor was smooth, the curved wall was broken by two windows. That was all.

"No controls?" asked Harlan.

"Remote controls," said Twissell. He ran his hand over the smoothness of the wall and said, "Double walls. The entire interwall volume is given over to a self-contained Temporal Field. This instrument is a kettle that is not restricted to the kettle shafts but can pa.s.s beyond the downwhen terminus of Eternity. Its design and construction were made possible by valuable hints in the Mallansohn memoir. Come with me."

The control room was a cut-off corner of the large room. Harlan stepped in and stared somberly at immense bus bars.

Twissell said, "Can you hear me, boy?"

Harlan started and looked about. He had not been aware that Twissell had not followed him inside. He stepped automatically to the window and Twissell waved to him. Harlan said, "I can hear you, sir. Do you want me outside?"

"Not at all. You are locked in."

Harlan sprang to the door and his stomach turned into a series of cold, wet knots. Twissell was correct and what in Time was going on?

Twissell said, "You will be relieved to know, boy, that your responsibility is over. You were worried about that responsibility; you asked searching questions about it; and I think I know what you meant. This should not be your responsibility. It is mine alone. Unfortunately, we must have you in the control room, since it is stated that you were there and handled the controls. It is stated in the Mallansohn memoir. Cooper will see you through the window and that will take care of that.

"Furthermore, I will ask you to make the final contact according to instructions I will give you. If you feel that that, too, is too great a responsibility, you may relax. Another contact in parallel with yours is in charge of another man. If, for any reason, you are unable to operate the contact, he will do so. Furthermore, I will cut off radio transmission from within the control room. You will be able to hear us but not to speak to us. You need not fear, therefore, that some involuntary exclamation from you will break the circle."

Harlan stared helplessly out the window.

Twissell went on, "Cooper will be here in moments and his trip to the Primitive will take place within two physiohours. After that, boy, the project will be over and you and I will be free."

Harlan was plunging chokingly through the vortex of a waking nightmare. Had Twissell tricked him? Had everything he had done been designed only to get Harlan quietly into a locked control room? Having learned that Harlan knew his own importance, had he improvised with diabolical cleverness, keeping him engaged in conversation, drugging his emotions with words, leading him here, leading him there, until the time was ripe for locking him in?

That quick and easy surrender over Noys. She won't be hurt, Twissell had said. All will be well.

How could he have believed that! If they were not going to harm her, or touch her, why the temporal barrier across the kettleways at the 100,000th? That alone should have given Twissell completely away.

But because he (fool!) wanted to believe, he allowed himself to be led through those last physiohours blindly, placed inside a locked room where he was no longer needed, even to close the final contact.

In one stroke he had been robbed of his essentiality. The trumps in his hand had been neatly maneuvered into deuces and Noys was out of his reach forever. What punishment might lie in wait for him did not concern him. Noys was out of his reach forever.

It had never occurred to him that the project would be so close to its end. That, of course, was what had really made his defeat possible.

Twissell's voice sounded dimly. "You'll be cut off now, boy."

Harlan was alone, helpless, useless. . . .

13 Beyond the Downwhen Terminus

Brinsley Cooper entered. Excitement flushed his thin face and made it almost youthful, despite the heavy Mallansohn mustache that draped its upper lip.

(Harlan could see him through the window, hear him clearly over the room's radio. He thought bitterly: A Mallansohn mustache! Of course!) Cooper strode toward Twissell. "They wouldn't let me in till now, Computer."

"Very right," said Twissell. "They had their instructions."

"Now's the time, though? I'll beheading out?"

"Almost the time."

"And I'll be coming back? I'll be seeing Eternity again?" Despite the straightness Cooper gave his back, there was an edge of uncertainty in his voice.

(Within the control room Harlan brought his clenched hands bitterly to the reinforced gla.s.s of the window, longing to break through somehow, to shout: "Stop it! Meet my terms, or I'll--" What was the use?) Cooper looked about the room, apparently unaware that Twissell had refrained from answering his question. His glance fell on Harlan at the control-room window.

He waved his hand excitedly. "Technician Harlan! Come on out. I want to shake your hand before I go."

Twissell interposed. "Not now, boy, not now. He's at the controls."

Cooper said, "Oh? You know, he doesn't look well."

Twissell said, "I've been telling him the true nature of the project. I'm afraid that's enough to make anyone nervous."

Cooper said, "Great Time, yes! I've known about it for weeks now and I'm not used to it yet." There was a trace of near-hysteria in his laugh. "I still haven't got it through my thick head that it is really my show. I--I'm a little scared."

"I scarcely blame you for that."

"It's my stomach, mostly, you know. It's the least happy part of me."

Twissell said, "Well, it's very natural and it will pa.s.s. Meanwhile, your time of departure on Standard Intertemporal has been set and there is still a certain amount of orientation to be gone through. For instance, you haven't actually seen the kettle you will use."

In the two hours that pa.s.sed Harlan heard it all, whether they were in sight or not. Twissell lectured Cooper in an oddly stilted manner, and Harlan knew the reason. Cooper was being informed of just those things that he was to mention in Mallansohn's memoir.

(Full circle. Full circle. And no way for Harlan to break that circle in one, last defiant Samson-smash of the temple. Round and round the circle goes; round and round it goes.) "Ordinary kettles," he heard Twissell say, "are both pushed and pulled, if we can use such terms in the case of Intertemporal forces. In traveling from Century X to Century Y within Eternity there is a fully powered initial point and a fully powered final point.

"What we have here is a kettle with a powered initial point but an unpowered destination point. It can only be pushed, not pulled. For that reason, it must utilize energies at a level whole orders of magnitude higher than those used by ordinary kettles. Special power-transfer units have had to be laid down along the kettleways to siphon in sufficient concentrations of energy from Nova Sol.

"This special kettle, its controls and power supply, are a composite structure. For physiodecades, the pa.s.sing Realities have been combed for special alloys and special techniques. The 13th Reality of the 222nd was the key. It developed the Temporal Pressor and without that, this kettle could not have been built. The 13th Reality of the 222nd."

He p.r.o.nounced that with elaborate distinctness.

(Harlan thought: Remember that, Cooper! Remember the 13th Reality of the 222nd so you can put it into the Mallansohn memoir so that the Etemals will know where to look so they will know what to tell you so you can put it. . . . Round and round the circle goes. . . .) Twissell said, "The kettle has not been tested past the downwhen terminus, of course, but it has taken numerous trips within Eternity. We are convinced there will be no bad effects."

"There can't be, can there?" said Cooper. "I mean I did get there or Mallansohn could not have succeeded in building the field and he _did_ succeed."

Twissell said, "Exactly. You will find yourself in a protected and isolated spot in the spa.r.s.ely populated southwestern area of the United States of Amellika-----"

"America," corrected Cooper.

"America, then. The Century will be the 24th; or, to put it to nearest hundredth, the 23.17th. I suppose we can even call it the year 2317, if we wish. The kettle, as you saw, is large, much larger than necessary for you. It is being filled now with food, water, and the means of shelter and defense. You will have detailed instructions that will, of course, be meaningless to anyone but you. I must impress upon you now that your first task will be to make certain that none of the indigenous inhabitants discovers you before you are ready for them. You will have force-diggers with which you will be able to burrow well into a mountain to form a cache. You will have to remove the contents of the kettle rapidly. They will be stacked so as to facilitate that."

(Harlan thought: Repeat! Repeat! He must have been told all this before, but repeat what must go into the memoir. Round and round . . .) Twissell said, "You will have to unload in fifteen minutes. After that, the kettle will return automatically to starting point, carrying with it all tools that are too advanced for the Century. You will have a list of those. After the kettle returns, you will be on your own."

Cooper said, "Must the kettle return so quickly?"

Twissell said, "A quick return increases the probabilities of success."

(Harlan thought: The kettle _must_ return in fifteen minutes because it _did_ return in fifteen minutes. Round and . . .) Twissell hurried on. "We cannot attempt to counterfeit their medium of exchange of any of their negotiable scrip. You will have gold in the form of small nuggets. You will be able to explain its possession according to your detailed instructions. You will have native clothing to wear or at least clothing that will pa.s.s for native."

"Right," said Cooper.

"Now, remember. Move slowly. Take weeks, if necessary. Work your way into the era, spiritually. Technician Harlan's instructions are a good basis but they are not enough. You will have a wireless receiver built on the principles of the z4th which will enable you to come abreast of the current events and, more important, learn the proper p.r.o.nunciation and intonation of the language of the times. Do that thoroughly. I'm sure that Harlan's knowledge of English is excellent, but nothing can subst.i.tute for native p.r.o.nunciation on the spot."

Cooper said, "What if I don't end up in the right spot? I mean, not in the 23.17?"

"Check on that very carefully, of course. But it will be right. It will be right."

(Harlan thought: It will be right because it was right. Round . . .) Cooper must have looked unconvinced, though, for Twissell said, "The accuracy of focus was carefully worked out. I intended to explain our methods and now is a good time. For one thing, it will help Harlan understand the controls."

(Suddenly Harlan turned away from the windows and fixed his gaze on the controls. A corner of the curtain of despair lifted. What if----) Twissell still lectured Cooper with the anxious overprecise tone of the schoolteacher, and with part of his mind Harlan still listened.

Twissell said, "Obviously a serious problem was that of determining how far into the Primitive an object is sent after the application of a given energy thrust. The most direct method would have been to send a man into the downwhen via this kettle using carefully graduated thrust levels. To do that, however, would have meant a certain lapse of time in each case while the man determined the Century to its nearest hundredth through astronomical observation or by obtaining appropriate information over the wireless. That would be slow and also dangerous since the man might well be discovered by the native inhabitants with probably catastrophic effects on our project.

"What we did then instead was this: We sent back a known ma.s.s of the radioactive isotope, niobium-94, which decays by beta-particle emission to the stable isotope, molybdenum-94. The process has a halflife of almost exactly 500 Centuries. The original radiation intensity of the ma.s.s was known. That intensity decreases with time according to the simple relationship involved in first-order kinetics, and, of course, the intensity can be measured with great precision.

"When the kettle reaches its destination in Primitive times, the ampule containing the isotope is discharged into the mountainside and the kettle then returns to Eternity. At the moment in physiotime that the ampule is discharged, it simultaneously appears at all future Times growing progressively older. At the place of discharge in the 575th (in actual Time and not in Eternity) a Technician detects the ampule by its radiation and retrieves it.

"The radiation intensity is measured, the time it has remained in the mountainside is then known, the Century to which the kettle traveled is also known to two decimal places. Dozens of ampules were thus sent back at various thrust levels and a calibration curve set up. The curve was a check against ampules sent not all the way into the Primitive but into the early Centuries of Eternity where direct observations could also be made.

"Naturally, there were failures. The first few ampules were lost until we learned to allow for the not too major geological changes between the late Primitive and the 575th. Then, three of the ampules later on never showed up in the 575th. Presumably, something went wrong with the discharge mechanism and they were buried too deeply in the mountain for detection. We stopped our experiments when the level of radiation grew so high that we feared that some of the Primitive inhabitants might detect and wonder what radioactive artifacts might be doing in the region. But we had enough for our purposes and we are certain we can send back a man to any hundredth of a Century of the Primitive that is desired.

"You follow all this, Cooper, don't you?"

Cooper said, "Perfectly, Computer Twissell. I have seen the calibration curve without understanding the purpose at the time. It is quite clear now."

But Harlan was exceedingly interested now. He stared at the measured arc marked off in centuries. The shining arc was porcelain on metal and the fine lines divided it into Centuries, Decicenturies and Centicenturies. Silvery metal gleamed thinly through the porcelainpenetrating lines, marking them clearly. The figures were as finely done and, bending close, Harlan could make out the Centuries from 17 to 27. The hairline was fixed at the 23.17th Century mark.

He had seen similar time-gauges and almost automatically he reached to the pressure-control lever. It did not respond to his grasp. The hairline remained in place.

He nearly jumped when Twissell's voice suddenly addressed him.

"Technician Harlan!"

He cried, "Yes, Computer," then remembered that he could not be heard. He stepped to the window and nodded.