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 the density of the atmosphere and the 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. Therefore Cloud concentrated upon the dials and gauges in front of him; concentrated with every fiber of his being and with every cell of his brain. Suddenly, almost imperceptably, the sigma curve gave signs of flattening out. Cloud’s mind pounced. Simultaneous differential equations; nine of them. A quadruple integration in four dimensions. No matter—Cloud did not solve problems laboriously, one operation at a time. Without knowing how he had arrived at it, he knew the answer; just as the Posenian or the Rigellian can perceive every separate component particle of an opaque, three-dimensional solid, but without being able to explain to any Tellurian how his sense of perception works. It just _is_, that’s all. By virtue of whatever sense or ability it is which makes a mathematical prodigy what he is, Cloud knew that in exactly seven and three-tenths seconds from that observed instant the activity of the vortex would match precisely the rating of his heaviest bomb. Another flick of his mental switch and he knew exactly the velocity he would require. His hand swept over the studs, his right foot tramped down hard upon the firing pedal; and, even as the quivering flitter rammed forward under five 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 would take him much closer to the vortex than he wanted to be; in fact, it would take him almost to the crater’s rim. But he stuck to the calculated course, and at the precisely correct instant he released his largest bomb and cut his dive. Then, in a continuation of the same motion, his hand slashed down through the beam of light whose cutting would activate the Bergenholm and make the vessel inertialess—safe from any form whatever of physical violence. For an instant nothing happened, and for that instant Cloud sat appalled. _Neutralization of inertia took time!_ Not that he had ever been told that it was instantaneous—he had just assumed so. He had never noticed any time-lapse before, but now it seemed to be taking forever!