It was getting to be a tiresome job, Mahler thought. But he was proud to hold it and be in a position to save millions of lives. It took a strong man to do what he was doing. He leaned back and awaited the arrival of the next jumper. Instead the door slid smoothly open, and the burly body of Dr. Fournet, the bureau’s chief medical man, broke the photoelectric beam. Mahler glanced up. Fournet carried a time rig dangling from one hand.

“I took this away from our latest customer,” Fournet said. “He told the medic who examined him that it was a two-way rig and I thought you’d better be the first to look it over.”

Mahler came to full attention quickly. A two-way rig? Unlikely, he thought. But if it was true it would mean the end of the dreary jumper prison on the Moon. Only how could a two-way rig exist? He reached out and took the rig from Fournet.

“It seems to be a conventional twenty-fourth century type,” he said.

“But notice the extra dial,” Fournet said, frowning. Mahler peered and nodded. “Yes. It seems to be a two-way rig, all right. But how can we test it? And it’s not really very probable,” he added. “Why should a two way rig suddenly show up from the twenty-fourth century, when no other traveler has one? We don’t even have two-way time travel ourselves, and our scientists insist that we never will.

“Still,” he mused, “it’s a nice thing to dream about. We’ll have to study this a little more closely. But I don’t seriously think it will work. Bring the jumper in, will you?”