"No dealer would believe that it was beaver. He'd think you were trying to pull a fast one on him. And there are only a few states that allow beaver to be trapped. To sell the pelts--even if you could--you'd have to take out licenses in each of those states." "Those mastodon carry a lot of ivory," said Cooper. "And if we wanted to go north, we'd find mammoths that would carry even more...." "And get socked into the jug for ivory smuggling?" They sat, all three of them, staring at the fire, not finding anything to say. The moaning complaint of a giant hunting cat came from somewhere up the river. IV 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.