There was a thin whining sound, and the wrapped, smoking object leaped upward. It seemed to fall toward the sky. There was no more of drama than that. An object the size of a basketball fell upward, swiftly, until it disappeared. Bordman sat quite still, watching the control-board dials. Presently he corrected this, and shifted that. He did not want the bomb to have too high an upward velocity. At a hundred thousand feet it would find very little air to stop the rise of the vapor it was to release. The field-focus dial reached its indication of one hundred thousand feet. Bordman reversed the lift-switch. He counted, and then switched the power off. The small, thin whine ended. He threw the power-intake switch. The power-yield needle stirred. The minute grid was drawing power like its vaster counterpart, but its field was infinitesimal by comparison. It drew power as a soda-straw might draw water from wet sand. Then the intake-needle kicked. It swung sharply, and wavered, and then began a steady, even, climbing movement across the markings on the dial-face. Riki was not watching that. "They see something!" she panted. "Look at them!" The four men who had trundled the smaller grid to its place, now stared upward. They flung out their arms. One of them jumped up and down. They leaped. They practically danced. "Let's go see," said Bordman. He went out of the tunnel with Riki. They gazed upward. And directly overhead, where the sky was darkest blue and where it had seemed that stars shone through the daylight, there was a minute cloud. But it grew. Its edges were yellow, saffron-yellow. It expanded and spread. Presently it began to thin. As it thinned, it began to shine. It was luminous. And the luminosity had a strange, familiar quality. Somebody came panting down the tunnel, from inside the mountain. "The grid--" he panted. "The big grid! It's pumping power! Big power! BIG power!" But Bordman was looking at the sky, as if he did not quite believe his eyes. The cloud now expanded very slowly, but still it grew. And it was not regular in shape. The bomb had not shattered quite evenly, and the vapor had poured out more on one side than the other. There was a narrow, arching arm of brightness.... "It looks," said Riki breathlessly, "like a comet!" And then Bordman froze in every muscle. He stared at the cloud he had made aloft, and his hands clenched in their mittens, and he swallowed behind his cold-mask. "Th-that's it," he said in a hushed voice. "It's--_very_ much like a comet. I'm glad you said that! We can make something even more like a comet. We can use all the bombs we've made, right away, to make it. And we've got to hurry so it won't get any colder tonight!" Which, of course, sounded like insanity. Riki looked apprehensively at him. But Bordman had just thought of something. And nobody had taught it to him and he hadn't gotten it out of books. But he'd seen a comet.