opaque defenses that indescribably ravening fireball, that esuriently rapacious monstrosity which might very well have come from the deepest pit of the hottest hell of mythology, felt strongly inclined to agree with Carlowitz. It didn't seem possible that anything could get any worse than that without exploding. And such an explosion, he felt sure, would certainly blow everything for miles around into the smitheriest kind of smithereens.

The activity of the vortex stayed high, 'way too high. The tiny control room of the flitter grew hotter and hotter. His skin burned and his eyes ached worse. He touched a communicator stud and spoke.

"Phil? Better get me three more bombs. Like these, except up around...."

"I don't check you. If you do that, it's apt to drop to a minimum and stay there," the Lensman reminded him. "It's completely unpredictable, you know."

"It may, at that ... so I'll have to forget the five percent margin and hit it on the nose or not at all. Order me up two more, then—one at half of what I've got here, the other double it," and he reeled off the figures for the charge and the casing of the explosive. "You might break out a jar of burn-dressing, too. Some fairly hot stuff is leaking through."

"We'll do that. Come down, fast!"

Cloud landed. He stripped to the skin and the observer smeared his every square inch of epidermis with the thick, gooey stuff that was not only a highly efficient screen against radiation, but also a sovereign remedy for new radiation burns. He exchanged his goggles for a thicker, darker, heavier pair. The two bombs arrived and were substituted for two of the original load.

"I thought of something while I was up there," Cloud informed the observers then. "Twenty kilograms of duodec is nobody's firecracker, but it may be the least of what's going to go off. Have you got any idea of what's going to become of the energy inside that vortex when I blow it out?"

"Can't say that I have." The Lensman frowned in thought. "No data."

"Neither have I. But I'd say that you better go back to the new station—the one you were going to move to if it kept on getting worse."

"But the instruments...." the Lensman was thinking, not of the instruments themselves, which were valueless in comparison with life, but of the records those instruments would make. Those records were priceless.

"I'll have everything on the tapes in the flitter," Cloud reminded.

"But suppose...."

"That the flitter stops one, too—or doesn't stop it, rather? In that case, your back station won't be there, either, so it won't make any difference." How mistaken Cloud was!

"QX," the Chief decided. "We'll leave when you do—just in case."

Again in air, Cloud found that the activity, while still high, was not too high, but that it was fluctuating too rapidly. He could not get even five seconds of trustworthy prediction, to say nothing of ten. So he waited, as close as he dared remain to that horrible center of disintegration.

The flitter hung poised in air, motionless, upon softly hissing under-jets. Cloud knew to a fraction his height above the ground. He knew to a fraction his distance from the vortex. He knew with equal certainty the density of the atmosphere and the exact velocity and direction of the wind. Hence, since he could also read closely enough the momentary variations in the cyclonic storms within the crater, he could compute very easily the course and velocity necessary to land the bomb in the exact center of the vortex at any given instant of time. The hard part—the thing that no one had as yet succeeded in doing—was to predict, for a time far enough ahead to be of any use, a usably close approximation to the vortex's quantitative activity. For, as has been said, he had to over-blast, rather than under-, if he could not hit it "on the nose:" to under-blast would scatter it all over the state.

Therefore Cloud concentrated upon the dials and gauges before him; concentrated with every fiber of his being and every cell of his brain.

Suddenly, almost imperceptibly, the Sigma curve gave signs of flattening out. In that instant Cloud's mind pounced. Simultaneous equations: nine of them, involving nine unknowns. An integration in four dimensions. No matter—Cloud did not solve them laboriously, one factor at a time. Without knowing how he had arrived at it, he knew the answer; just as the Posenian or the Rigellian is able to perceive every separate component particle of an opaque, three-dimensional solid, but without being able to explain to anyone how his sense of perception works. It just is, that's all.

Anyway, by virtue of whatever sense or ability it is which makes a mathematical prodigy what he is, Cloud knew that in exactly eight and three-tenths seconds from that observed instant the activity of the vortex would be slightly—but not too far—under the coefficient of his heaviest bomb. Another flick of his mental trigger and he knew the exact velocity he would require. His hand swept over the studs, his right foot tramped down, hard, upon the firing lever; and, even as the quivering flitter shot forward under eight Tellurian gravities of acceleration, he knew to the thousandth of a second how long he would have to hold that acceleration to attain that velocity. While not really long—in seconds—it was much too long for comfort. It took him much closer to the vortex than he wanted to be; in fact, it took him right out over the crater itself.

But he stuck to the calculated course, and at the precisely correct instant he cut his drive and released his largest bomb. Then, so rapidly that it was one blur of speed, he again kicked on his eight G's of drive and started to whirl around as only a speedster or a flitter can whirl. Practically unconscious from the terrific resultant of the linear and angular accelerations, he ejected the two smaller bombs. He did not care particularly where they lit, just so they didn't light in the crater or near the observatory, and he had already made certain of that. Then, without waiting even to finish the whirl or to straighten her out in level flight, Cloud's still-flying hand darted toward the switch whose closing would energize the Bergenholm and make the flitter inertialess.

Too late. Hell was out for noon, with the little speedster still inert. Cloud had moved fast, too; trained mind and trained body had been working at top speed and in perfect coordination. There just simply hadn't been enough time. If he could have got what he wanted, ten full seconds, or even nine, he could have made it, but....

In spite of what happened, Cloud defended his action, then and thereafter. Damnitall, he had to take the eight-point-three second reading! Another tenth of a second and his bomb wouldn't have fitted—he didn't have the five percent leeway he wanted, remember. And no, he couldn't wait for another match, either. His screens were leaking like sieves, and if he had waited for another chance they would have picked him up fried to a greasy cinder in his own lard!

The bomb sped truly and struck the target in direct central impact, exactly as scheduled. It penetrated perfectly. The neocarballoy casing lasted just long enough—that frightful charge of duodec exploded, if not exactly at the center of the vortex, at least near enough to the center to do the work. In other words, Cloud's figuring had been close—very close. But the time had been altogether too short.

The flitter was not even out of the crater when the bomb went off. And not only the bomb. For Cloud's vague forebodings were materialized, and more; the staggeringly immense energy of the vortex merged with that of the detonating duodec to form an utterly incomprehensible whole.

In part the hellish flood of boiling lava in that devil's cauldron was beaten downward into a bowl by the sheer, stupendous force of the blow; in part it was hurled abroad in masses, in gouts and streamers. And the raging wind of the explosion's front seized the