little stream, the poolwhere he had bathed his feet, the clump of seedling pines under which hehad slept. He even found the silver-foil wrapping from the foodconcentrate capsule.

  But there had been a change, since the night when he had slept here.Then the young pines had been green and alive; now they were blighted,and their needles had turned brown. Hradzka stood for a long time,looking at them. It was the same blight that had touched the plantsaround the farmhouse. And here, among the pine needles on the ground,lay a dead bird.

  It took some time for him to admit, to himself, the implications ofvegetation, the chickens, the cow, the farmer and his wife, had allsickened and died. He had been in this place, and now, when he hadreturned, he found that death had followed him here, too.

  * * * * *

  During the early centuries of the Atomic Era, he knew, there had beengreat wars, the stories of which had survived even to the HundredthCentury. Among the weapons that had been used, there had been artificialplagues and epidemics, caused by new types of bacteria developed inlaboratories, against which the victims had possessed no protection.Those germs and viruses had persisted for centuries, and gradually hadlost their power to harm mankind. Suppose, now, that he had brought someof them back with him, to a century before they had been developed.Suppose, that was, that he were a human plague-carrier. He thought ofthe vermin that had infested the clothing he had taken from the man hehad killed on the other side of the mountain; they had not troubled himafter the first day.

  There was a throbbing mechanical sound somewhere in the air; he lookedabout, and finally identified its source. A small aircraft had come overthe valley from the other side of the mountain and was circling lazilyoverhead. He froze, shrinking back under a pine-tree; as long as heremained motionless, he would not be seen, and soon the thing would goaway. He was beginning to understand why the search for him was beingpressed so relentlessly; as long as he remained alive, he was a menaceto everybody in this First Century world.

  He got out his supply of food concentrates, saw that he had only threecapsules left, and put them away again. For a long time, he sat underthe dying tree, chewing on a twig and thinking. There must be some wayin which he could overcome, or even utilize, his inherent deadliness tothese people. He might find some isolated community, conceal himselfnear it, invade it at night and infect it, and then, when everybody wasdead, move in and take it for himself. But was there any such isolatedcommunity? The farmhouse where he had worked had been fairly remote, yetits inhabitants had been in communication with the outside world, andthe physician had come immediately in response to their call for help.

  The little aircraft had been circling overhead, directly above the placewhere he lay hidden. For a while, Hradzka was afraid it had spotted him,and was debating the advisability of using his blaster on it. Then itbanked, turned and went away. He watched it circle over the valley onthe other side of the mountain, and got to his feet.

  4

  Almost at once, there was a new sound--a multiple throbbing, at a quick,snarling tempo that hinted at enormous power, growing louder eachsecond. Hradzka stiffened and drew his blaster; as he did, five moreaircraft swooped over the crest of the mountain and came rushing downtoward him; not aimlessly, but as though they knew exactly where he was.As they approached, the leading edges of their wings sparkled withlight, branches began flying from the trees about him, and there was aloud hammering noise.

  He aimed a little in front of them and began blasting. A wing flew fromone of the aircraft, and it plunged downward. Another came apart in theair; a third burst into flames. The other two zoomed upward quickly.Hradzka swung his blaster after them, blasting again and again. He hit afourth with a blast of energy, knocking it to pieces, and then the fifthwas out of range. He blasted at it twice, but without effect; ahand-blaster was only good for a thousand yards at the most.

  Holstering his weapon, he hurried away, following the stream and keepingunder cover of trees. The last of the attacking aircraft had gone away,but the little scout-plane was still circling about, well out ofblaster-range.

  Once or twice, Hradzka was compelled to stay hidden for some time, notknowing the nature of the pilot's ability to detect him. It was duringone of these waits that the next phase of the attack developed.

  It began, like the last one, with a distant roar that swelled in volumeuntil it seemed to fill the whole world. Then, fifteen or twentythousand feet out of blaster-range, the new attackers swept into sight.

  There must have been fifty of them, huge tapering things withwide-spread wings, flying in close formation, wave after V-shaped wave.He stood and stared at them, amazed; he had never imagined that suchaircraft existed in the First Century. Then a high-pitched screamingsound cut through the roar of the propellers, and for an instant he sawcountless small specks in the sky, falling downward.

  The first bomb-salvo landed in the young pines, where he had foughtagainst the first air attack. Great gouts of flame shot upward, andsmoke, and flying earth and debris. Hradzka turned and started to run.Another salvo fell in front of him; he veered to the left and plunged onthrough the undergrowth. Now the bombs were falling all about him,deafening him with their thunder, shaking him with concussion. Hedodged, frightened, as the trunk of a tree came crashing down besidehim. Then something hit him across the back, knocking him flat. For amoment, he lay stunned, then tried to rise. As he did, a searing lightfilled his eyes and a wave of intolerable heat swept over him. Thendarkness...

  * * * * *

  "No, Zarvas Pol," Kradzy Zago repeated. "Hradzka will not return; the'time-machine' was sabotaged."

  "So? By you?" the soldier asked.

  The scientist nodded. "I knew the purpose for which he intended it.Hradzka was not content with having enslaved a whole Solar System: hehungered to bring tyranny and serfdom to all the past and all the futureas well; he wanted to be master not only of the present but of thecenturies that were and were to be, as well. I never took part inpolitics, Zarvas Pol; I had no hand in this revolt. But I could not beparty to such a crime as Hradzka contemplated when it lay within mypower to prevent it."

  "The machine will take him out of our space-time continuum, or back to atime when this planet was a swirling cloud of flaming gas?" Zarvas Polasked.

  Kradzy Zago shook his head. "No, the unit is not powerful enough forthat. It will only take him about ten thousand years into the past. Butthen, when it stops, the machine will destroy itself. It may destroyHradzka with it or he may escape. But if he does, he will be leftstranded ten thousand years ago, when he can do us no harm.

  "Actually, it did not operate as he imagined and there is an infinitelysmall chance that he could have returned to our 'time', in any event.But I wanted to insure against even so small a chance."

  "We can't be sure of that," Zarvas Pol objected. "He may know more aboutthe machine than you think; enough more to build another like it. So youmust build me a machine and I'll take back a party of volunteers andhunt him down."

  "That would not be necessary, and you would only share his fate." Then,apparently changing the subject, Kradzy Zago asked: "Tell me, ZarvasPol; have you never heard the legends of the Deadly Radiations?"

  General Zarvas smiled. "Who has not? Every cadet at the Officers'College dreams of re-discovering them, to use as a weapon, but nobodyever has. We hear these tales of how, in the early days, atomic enginesand piles and fission-bombs emitted particles which were utterly deadly,which would make anything with which they came in contact deadly, whichwould bring a horrible death to any human being. But these are onlymyths. All the ancient experiments have been duplicated time and again,and the deadly radiation effect has never been observed. Some say thatit is a mere old-wives' terror tale; some say that the deaths werecaused by fear of atomic energy, when it was still unfamiliar; otherscontend that the fundamental nature of atomic energy has altered by thedegeneration of the fissionable matter. For my own part, I'm not enoughof a scientist to have an
opinion."

  * * * * *

  The old one smiled wanly. "None of these theories are correct. In thebeginning of the Atomic Era, the Deadly Radiations existed. They stillexist, but they are no longer deadly, because all life on this planethas adapted itself to such radiations, and all living things are nowimmune to them."

  "And Hradzka has returned to a time when such immunity did not exist?But would that not be to his advantage?"

  "Remember, General, that man has been using atomic energy for tenthousand years. Our whole world has become drenched with radioactivity.The planet, the seas, the atmosphere, and every living thing, are allradioactive, now. Radioactivity is as natural to us as the air webreathe. Now, you remember hearing of the great wars of the firstcenturies of the Atomic Era, in which whole nations were wiped out,leaving only hundreds of survivors