With the space-flier's form decided and the plans for it drafted, work upon it had begun at once. At the World President's suggestion, it was being set up on the great flat roof of the World Government building. From over all Earth had come the world's most brilliant engineers and scientists to aid in its construction, for the world lay still beneath the great shadowing wing of fear that had been cast over it, when the peoples of Earth had learned first of the doom that Neptune and its beings were loosing upon the solar system. So that though the world's first wild panic had subsided, it had been replaced by a waxing realization and dread that had made the peoples of Earth and their representatives offer to us their help in this plan of ours, which alone held out any chance, however slender, of escape from the annihilation that was nearing Earth. Laboring ceaselessly day and night therefore, in picked crews of workers that every few hours replaced each other, Dr. Marlin and Randall and myself and our eager workers had swiftly brought the great space-flier's metal shell into being. That great crystal-like shell, at Dr. Marlin's suggestion, had been made double-walled, the space between the two walls being pumped to as complete a vacuum as possible so that vacuum might insulate the flier's interior from the tremendous differences in temperature that it would meet in space. For where the sun's heat-radiations struck the flier in space it would be warm, hot even, but those parts in shadow would be subjected to the absolute zero of empty space. Each of these thick double walls, in turn, was itself built up of alternate layers of finest steel and of non-metallic, asbestos-like insulating material, pressed and welded together by titanic forces into a single thickness. And the great faceted wall-sections of the flier, when in place, had been so welded and fused one to the other by the new molecular-diffusion fusing process, that the great ball-like faceted flier might have been and was, in fact, a single and seamless polyhedron, its strength enormous.