"What do your people think it is?"

Eggerton smiled and shook his head. "They don't know. There you are. At first, some of them thought it was some kind of force field. But the mathematics won't work, and of course it's cold. Terribly cold. I am mumbling. I am not a scientist and not a mathematician, but they also mumble, Mr. Felton. I am tired of that kind of thing. That is why I asked you to come to Washington and talk with us. I thought you might know."

"I might," Felton nodded.

For the first time, Eggerton became alive, excited, impatient. He mixed Felton another drink. Then he leaned forward eagerly and waited. Felton took a letter out of his pocket.

"This came from my sister," he said.

"You told me you had no letter from her in almost a year!"

"I've had this almost a year," Felton replied, a note of sadness in his voice. "I haven't opened it. She enclosed this sealed envelope with a short letter, which only said that she was well and quite happy, and that I was to open and read the other letter when it was absolutely necessary to do so. My sister is like that; we think the same way. Now, I suppose it's necessary, don't you?"

The secretary nodded slowly but said nothing. Felton opened the letter and began to read aloud.

June 2, 1964

My dear Harry:

As I write this, it is twenty-two years since I have seen you or spoken to you. How very long for two people who I have such love and regard for each other as we do. And now that you have found it necessary to open this letter and read it, we must face the fact that in all probability we will never see each other again. I hear that you have a wife and three children — all wonderful people. I think it is hardest to know that I will not see them or know them.

Only this saddens me. Otherwise, Mark and I are very happy — and I think you will understand why.