Einstein sat silent for a moment before he answered. "No, there was no opportunity. I have always been sure that they could be constructed, but have never put it to the test. The Germans felt the same, and at one time even had a heavy water project that aimed towards controlled nuclear fission. But their military successes were so great that they abandoned it along with other far-fetched and expensive schemes such as the hollow-globe theory. I myself have never wanted to see this hellish thing built, and from what you have told about it, it is worse than my most terrible dream. But I have approached the President about it, when the Nazi threat was closing in, but nothing was done. Too expensive. Now it is too late. But perhaps it isn't. If _your_ America will help us, the enemy will be defeated. And after that, what a wealth of knowledge we shall have once our worlds are in contact. Will you do it?" "Of course," Dan Coye said. "But the brass will take a lot of convincing. I suggest some films be made of you and others explaining some of this. And enclose some documents, anything that will help convince them what has happened." "I can do something better," Einstein said, taking a small bottle from a drawer of the table. "Here is a recently developed drug, and the formula, that has proved effective in arresting certain of the more violent forms of cancer. This is an example of what I mean by the profit that can accrue when our two worlds can exchange information." Dan pocketed the precious bottle as they turned to leave. With a sense of awe they gently shook hands with the frail old man who had been dead many years in the world they knew, to which they would be soon returning. * * * * * The military moved fast. A large jet bomber was quickly converted to carry one of the American solid-fuel rocket missiles. Not yet operational, it was doubtful if they ever would be at the rate of the Nazi advance. But given an aerial boost by the bomber it could reach up out of the ionosphere--carrying the payload of the moon capsule with its two pilots. Clearing the fringes of the atmosphere was essential to the operation of the instrument that was to return them to what they could only think of as their own world. It seemed preposterously tiny to be able to change worlds. "Is that _all_?" Gino asked when they settled themselves back into the capsule. A square case, containing records and reels of film, was strapped between their seats. On top of it rested a small grey metal box. "What do you expect--an atom smasher?" Dan asked, checking out the circuits. The capsule had been restored as much as was possible to the condition it was in the day it had landed. The men wore their pressure suits. "We came here originally by accident, by just thinking wrong or something like that, if my theory's correct." "It isn't--but neither is mine, so we can't let it bug us."