Hudson lay in his sleeping bag, staring at the sky. It bothered him a lot. There was not one familiar constellation, not one star that he could name with any certainty. This juggling of the stars, he thought, emphasized more than anything else in this ancient land the vast gulf of years which lay between him and the Earth where he had been—or would be—born.

A hundred and fifty thousand years, Adams had said, give or take ten thousand. There just was no way to know. Later on, there might be. A measurement of the stars and a comparison with their positions in the twentieth century might be one way of doing it. But at the moment, any figure could be no more than a guess.

The time machine was not something that could be tested for calibration or performance. As a matter of fact, there was no way to test it. They had not been certain, he remembered, the first time they had used it, that it would really work. There had been no way to find out. When it worked, you knew it worked. And if it hadn't worked, there would have been no way of knowing beforehand that it wouldn't.

Adams had been sure, of course, but that had been because he had absolute reliance in the half-mathematical, half-philosophic concepts he had worked out—concepts that neither Hudson nor Cooper could come close to understanding.

That had always been the way it had been, even when they were kids, with Wes dreaming up the deals that he and Johnny carried out. Back in those days, too, they had used time travel in their play. Out in Johnny's back yard, they had rigged up a time machine out of a wonderful collection of salvaged junk—a wooden crate, an empty five-gallon paint pail, a battered coffee maker, a bunch of discarded copper tubing, a busted steering wheel and other odds and ends. In it, they had "traveled" back to Indian-before-the-white-man land and mammoth-land and dinosaur-land and the slaughter, he remembered, had been wonderfully appalling.

But, in reality, it had been much different. There was much more to it than gunning down the weird fauna that one found.

And they should have known there would be, for they had talked about it often.

He thought of the bull session back in university and the little, usually silent kid who sat quietly in the corner, a law-school student whose last name had been Pritchard.

And after sitting silently for some time, this Pritchard kid had spoken up: "If you guys ever do travel in time, you'll run up against more than you bargain for. I don't mean the climate or the terrain or the fauna, but the economics and the politics."

They all jeered at him, Hudson remembered, and then had gone on with their talk. And after a short while, the talk had turned to women, as it always did.

He wondered where that quiet man might be. Some day, Hudson told himself, I'll have to look him up and tell him he was right.

We did it wrong, he thought. There were so many other ways we might have done it, but we'd been so sure and greedy—greedy for the triumph and the glory—and now there was no easy way to collect.

On the verge of success, they could have sought out help, gone to some large industrial concern or an educational foundation or even to the government. Like historic explorers, they could have obtained subsidization and sponsorship. Then they would have had protection, funds to do a proper job and they need not have operated on their present shoestring—one beaten-up helicopter and one time unit. They could have had several and at least one standing by in the twentieth century as a rescue unit, should that be necessary.

But that would have meant a bargain, perhaps a very hard one, and sharing with someone who had contributed nothing but the money. And there was more than money in a thing like this—there were twenty years of dreams and a great idea and the dedication to that great idea—years of work and years of disappointment and an almost fanatical refusal to give up.

Even so, thought Hudson, they had figured well enough. There had been many chances to make blunders and they'd made relatively few. All they lacked, in the last analysis, was backing.

Take the helicopter, for example. It was the one satisfactory vehicle for time traveling. You had to get up in the air to clear whatever upheavals and subsidences there had been through geologic ages. The helicopter took you up and kept you clear and gave you a chance to pick a proper landing place. Travel without it and, granting you were lucky with land surfaces, you still might materialize in the heart of some great tree or end up in a swamp or the middle of a herd of startled, savage beasts. A plane would have done as well, but back in this world, you couldn't land a plane—or you couldn't be certain that you could. A helicopter, though, could land almost anywhere.

In the time-distance they had traveled, they almost certainly had been lucky, although one could not be entirely sure just how great a part of it was luck. Wes had felt that he had not been working as blindly as it sometimes might appear. He had calibrated the unit for jumps of 50,000 years. Finer calibration, he had said realistically, would have to wait for more developmental work.

Using the 50,000-year calibrations, they had figured it out. One jump (conceding that the calibration was correct) would have landed them at the end of the Wisconsin glacial period; two jumps, at its beginning. The third would set them down toward the end of the Sangamon Interglacial and apparently it had—give or take ten thousand years or so.

They had arrived at a time when the climate did not seem to vary greatly, either hot or cold. The flora was modern enough to give them a homelike feeling. The fauna, modern and Pleistocenic, overlapped. And the surface features were little altered from the twentieth century. The rivers ran along familiar paths, the hills and bluffs looked much the same. In this corner of the Earth, at least, 150,000 years had not changed things greatly.

Boyhood dreams, Hudson thought, were wondrous. It was not often that three men who had daydreamed in their youth could follow it out to its end. But they had and here they were.

Johnny was on watch, and it was Hudson's turn next, and he'd better get to sleep. He closed his eyes, then opened them again for another look at the unfamiliar stars. The east, he saw, was flushed with silver light. Soon the Moon would rise, which was good. A man could keep a better watch when the Moon was up.

He woke suddenly, snatched upright and into full awareness by the marrow-chilling clamor that slashed across the night. The very air seemed curdled by the savage racket and, for a moment, he sat numbed by it. Then, slowly, it seemed—his brain took the noise and separated it into two distinct but intermingled categories, the deadly screaming of a cat and the maddened trumpeting of a mastodon.

The Moon was up and the countryside was flooded by its light. Cooper, he saw, was out beyond the watchfires, standing there and watching, with his rifle ready. Adams was scrambling out of his sleeping bag, swearing softly to himself. The cooking fire had burned down to a bed of mottled coals, but the watchfires still were burning and the helicopter, parked within their circle, picked up the glint of flames.

"It's Buster," Adams told him angrily. "I'd know that bellowing of his anywhere. He's done nothing but parade up and down and bellow ever since we got here. And now he seems to have gone out and found himself a saber-tooth."

Hudson zipped down his sleeping bag, grabbed up his rifle and jumped to his feet, following Adams in a silent rush to where Cooper stood.

Cooper motioned at them. "Don't break it up. You'll never see the like of it again."

Adams brought his rifle up.

Cooper knocked the barrel down.

"You fool!" he shouted. "You want them turning on us?"

Two hundred yards away stood the mastodon and, on his back, the screeching saber-tooth. The great beast reared into the air and came down with a jolt, bucking to unseat the cat, flailing the air with his massive trunk. And as he bucked, the cat struck and struck again with his gleaming teeth, aiming for the spine.

Then the mastodon crashed head downward, as if to turn a somersault, rolled and was on his feet again, closer to them now than he had been before. The huge cat had sprung off.

For a moment, the two stood facing one another. Then the tiger charged, a flowing streak of motion in the moonlight. Buster wheeled away and the cat, leaping, hit his shoulder, clawed wildly and slid off. The mastodon whipped to the attack, tusks slashing, huge feet stamping. The cat, caught a glancing blow by one of the tusks, screamed and leaped up, to land in spread-eagle fashion upon Buster's head.

Maddened with pain and fright, blinded by the tiger's raking claws, the old mastodon ran—straight toward the camp. And as he ran, he grasped the cat in his trunk and tore him from his hold, lifted him high and threw him.

"Look out!" yelled Cooper and brought his rifle up and fired.

For an instant, Hudson saw it all as if it were a single scene, motionless, one frame snatched from a fantastic movie epic—the charging mastodon, with the tiger lifted and the sound track one great blast of bloodthirsty bedlam.

Then the scene dissolved in a blur of motion. He felt his rifle thud against his shoulder, knowing he had fired, but not hearing the explosion. And the mastodon was almost on top of him, bearing down like some mighty and remorseless engine of blind destruction.

He flung himself to one side and the giant brushed past him. Out of the tail of his eye, he saw the thrown saber-tooth crash to Earth within the circle of the watchfires.

He brought his rifle up again and caught the area behind Buster's ear within his sights. He pressed the trigger. The mastodon staggered, then regained his stride and went rushing on. He hit one of the watchfires dead center and went through it, scattering coals and burning brands.

Then there was a thud and the screeching clang of metal.

"Oh, no!" shouted Hudson.

Rushing forward, they stopped inside the circle of the fires.

The helicopter lay tilted at a crazy angle. One of its rotor blades was crumpled. Half across it, as if he might have fallen as he tried to bull his mad way over it, lay the mastodon.

Something crawled across the ground toward them, its spitting, snarling mouth gaping in the firelight, its back broken, hind legs trailing.

Calmly, without a word, Adams put a bullet into the head of the saber-tooth.