“Yes. The radioactivity had died down enough so that Team A reported no danger to itself, but some of the longer-lived isotopes were still measurably present. By making differential measurements of abundance, Team A was able to estimate rather closely when the bombs had gone off.”

“And?”

“Approximately one year from the twentieth-century base date we are presently using.”

“One year…from now.” Herries stared upward. Blackness met him. He heard the Jurassic rain on the iron roof, like drums.

“Possibly less,” Symonds told him. “There is a factor of uncertainty. This project must be completed well within the safety margin before the war comes.”

“The war comes,” Herries repeated…“Does it have to come? Fixed time line or not, does it have to come? Couldn’t the enemy leaders be shown the facts—couldn’t our side, even, capitulate—”

“Every effort is being made,” said Symonds like a machine. “Quite apart from the theory of rigid time, it seems unlikely that they will succeed. The situation is too unstable. One man, losing his head and pressing the wrong button, can write the end; and there are so many buttons. The very revelation of the truth, to a few chosen leaders or to the world public, would make some of them panicky. Who can tell what a man in panic will do? That is what I meant when I said that Senator Wien and his coworkers have not forgotten their oaths of office. They have no thought of taking refuge, they know they are old men. To the end, they will try to save the twentieth century. But they do not expect it; so they are also trying to save the human race.”

Herries pushed up from the crate he had been leaning against. “Those five hundred who’re coming,” he whispered. “Women?”

“Yes. If there is still time to rescue a few more, after the ones you are preparing for have gone through, it will be done. But there will be at least a thousand young, healthy adults here, in the Jurassic. You face a difficult time, when the truth must be told them; you can see why the secret must be kept until then. It is quite possible that someone here will lose his head. That is why no heavy weapons have been sent: a single deranged person must not be able to destroy everyone. But you will recover. You must.”

Herries jerked the door open and stared out into the roaring darkness. “But there are no traces of us…in the future,” he said, hearing his voice high and hurt like a child’s.

“How much trace do you expect would remain after geological eras?” answered Symonds. He was still the reproving schoolmaster; but he sat on the barrel and faced the great moving shadows in a corner. “It is assumed that you will remain here for several generations, until your numbers and resources have been expanded sufficiently. The Team A I spoke of will join you a century hence. It is also, I might add, composed of young men and women in equal numbers. But this planet in this age is not a good home. We trust that your descendants will perfect the spaceships we know to be possible, and take possession of the stars instead.”