They came upon an open gallery, and there was a security man looking down at the floor and the Platform. He had a very good view of all that went on. They went around another long circuit of the slanting gallery, dimly lighted with small electric bulbs. They came to a second gallery, and saw the Platform again. There was another guard here. They were halfway up the globular wall now, and were visibly suspended over emptiness. The view of the Platform was impressive. There were an astonishing number of rocket tubes being fastened to the outside of that huge object. Three giant cranes, working together, hoisted a tube to the last remaining level of scaffolding, and men swarmed on it and fastened it to the swelling hull. As soon as it was fast, other men hurried into it with the white pasty stuff to line it from end to end. The tubes would nearly hide the structure they were designed to propel. But they'd all be burned away when it reached its destination. "Wonderful, isn't it?" asked Sally hopefully. Joe looked, and said without warmth, "It's the most wonderful thing that anybody ever even tried to do." Which was true enough, but the zest of it had unreasonably departed for Joe for the time being. His disappointment was new. Halfway around again, Sally opened a door, and Joe was almost surprised out of his lethargy. Here was a watching post on the outside of the monstrous half-globe. There were two guards here, with fifty-caliber machine guns under canvas hoods. Their duties were tedious but necessary. They watched the desert. From this height it stretched out for miles, and Bootstrap could be seen as a series of white specks far away with hills behind it. Ultimately Sally and Joe came to the very top of the Shed into the open air. From here the steep plating curved down and away in every direction. The sunshine was savagely bright and shining, but there was a breeze. And here there was a considerable expanse fenced in--almost an acre, it seemed. There were metal-walled small buildings with innumerable antennae of every possible shape for the reception of every conceivable wave length. There were three radar bowl reflectors turning restlessly to scan the horizon, and a fourth which went back and forth, revolving, to scan the sky itself. Sally told Joe that in the very middle--where there was a shed with a domelike roof which wasn't metal--there was a wave-guide radar that could spot a plane within three feet vertically, and horizontally at a distance of thirty miles, with greater distances in proportion. There were guns down in pits so their muzzles wouldn't interfere with the radar. There were enough non-recoil anti-aircraft guns to defend the Shed against anything one could imagine. "And there are jet planes overhead too," said Sally. "Dad asked to have them reinforced, and two new wings of jet fighters landed yesterday at a field somewhere over yonder. There are plenty of guards!"