Minnie happy on her island, her lesson well learned. She would no longer so much as step on the inner strip of metal foil. It was a mouse-paradise of an island, though. There was a cliff of cheese bigger than Minnie herself. It kept her busy. Mouse and cheese; soon one would be a transmutation of the other. But Professor Oberburger wasn't thinking about that. The Professor was worried. When he had calculated and re-calculated and aimed his eight-inch reflector through the hole in the roof and turned out the lights-- Yes, there _are_ advantages to being a bachelor after all. If one wants a hole in the roof, one simply knocks a hole in the roof and there is nobody to tell one that one is crazy. If winter comes, or if it rains, one can always call a carpenter or use a tarpaulin. But the faint trail of light wasn't there. The Professor frowned and re-calculated and re-re-calculated and shifted his telescope three-tenths of a minute and still the rocket wasn't there. "Minnie, something iss wrong. Either der tubes haff stopped viring, or--" Or the rocket was no longer traversing a straight line relative to its point of departure. By straight, of course, is meant parabollically curved relative to everything other than velocity. So the Herr Professor did the only thing remaining for him to do, and began to search, with the telescope, in widening circles. It was two hours before he found it, five degrees off course already and veering more and more into a--Well, there was only one thing you could call it. A tailspin. The darned thing was going in circles, circles which appeared to constitute an orbit about something that couldn't possibly be there. Then narrowing into a concentric spiral. Then--out. Gone. Darkness. No rocket flares. The Professor's face was pale as he turned to Minnie. "It iss _imbossible_, Minnie. Mein own eyes, but it could not be. Even if vun side stopped viring, it could not haff gone into such sudden circles." His pencil verified a suspicion. "Und, Minnie, it decellerated vaster than bossible. Even mitt _no_ tubes viring, its momentum vould haff been more--" The rest of the night--telescope and calculus--yielded no clue. That is, no believable clue. Some force not inherent in the rocket itself, and not accountable by gravitation--even of a hypothetical body--had acted. "Mein poor Mitkey." [Illustration: "POOR MITKEY"] The gray, inscrutable dawn. "Mein Minnie, it vill haff to be a secret. Ve dare not bublish vhat ve saw, for it vould not be believed. I am not sure I believe it myself, Minnie. Berhaps because I vas offertired vrom not sleeping, I chust imachined that I saw--"