"Nobody else thought of it, either, until just now," Kinnison broke in. "However, I'm not afraid of duodec—don't see how they could control it accurately enough at this three-dimensional distance. Too deep, it wouldn't explode at all. What I don't like to think of, though, is a negasphere. Or a planet, perhaps."

"Ideas? Suggestions?" the admiral snapped.

"No—I don't know anything about the stuff. How about putting our Lenses on Cardynge?"

"That's a thought!" and in seconds they were in communication with Sir Austin Cardynge, Earth's mightiest mathematical brain.

"Kinnison, how many times must I tell you that I am not to be interrupted?" the aged scientist's thought was a crackle of fury. "How can I concentrate upon vital problems if every young whippersnapper in the System is to perpetrate such abominable, such outrageous intrusions—"

"Hold it, Sir Austin—hold everything!" Kinnison soothed. "I'm sorry. I wouldn't have intruded if it hadn't been a matter of life or death. But it would be a worse intrusion, wouldn't it, if the Boskonians sent a planet about the size of Jupiter—or a negasphere—through one of their extradimensional vortices into your study? That's exactly what they're figuring on doing."

"What ... what ... what?" Cardynge snapped, like a string of firecrackers. He quieted down, then, and thought. And Sir Austin Cardynge could think, upon occasion and when he felt so inclined; could think in the abstruse symbology of pure mathematics with a cogency equaled by few minds in the Universe. Both Lensmen perceived those thoughts, but neither could understand or follow them. No mind not a member of the Conference of Scientists could have done so.

"They can't!" of a sudden the mathematician cackled, gleefully disdainful. "Impossible—quite definitely impossible. There are laws governing such things, Kinnison, my impetuous and ignorant young friend. The terminus of the necessary hypertube could not be established within such proximity to the mass of the Sun. This is shown by—"

"Never mind the proof—the fact is enough," Kinnison interposed, hastily. "How close to the Sun could it be established?"

"I couldn't say, offhand," came the cautiously scientific reply. "More than two astronomical units, certainly, but the computation of the exact distance would require some little time. It would, however, be an interesting, if minor, problem. I will solve it for you, if you like, and advise you of the exact minimum distance."