Even from the top of the spiral the clamor had to be heard to be believed. But what astounded me most was the newness, brightness, sharply delineated aspect of everything within range of my vision. I could see clear to the edge of the spaceport, and the four other securely-berthed rockets stood out with a startling clarity, their nose cones gleaming in the bright Martian sunlight. The big lifting cranes stood out just as sharply, and although the zigzagging tractors looked like painted toys, red and blue and yellow, I would have sworn under oath that not one of them cast a shadow. The twenty-five or thirty human midgets who were moving in all directions across the field, between machines that seemed too formidable to be trusted had the brittle, sheen-bright look of figures cut out of isinglass. Another illusion, of course. There had to be shadows, because there was nothing on Mars that could have brought about that big a change in the laws of optics. But by the same token the length and density of shadows can be altered a bit by atmospheric conditions, making light interception turn playful. So I didn't strain my eyes searching for deep purple halos around the human midges. My only immediate concern was to reassure Joan in a calm and forceful way and escort her safely down to ground level, without letting her suspect that I shared her misgivings as to the stability of the spiral. It was ridiculous on the face of it. But, as I've said, you can't argue with a feeling that whispers that your remote, dawn age ancestors must have felt the same way when they climbed out on a limb overhanging a precipice, and felt the whole tree begin to sway and shake beneath them. "Hold tight to the rail and don't look down," I cautioned. "There's no real danger ... because a first-rate welding job was done on this structure. Barring an earthquake, it should be just as safe a century from now." I shot a quick, concerned glance at her along with the warning. I guess I must have thought she'd be more shaken than she was, for she smiled when she saw the look of surprise in my eyes. It took me half a minute to realize that my guess as to how she'd be taking it hadn't gone so wide of the mark. Her pallor gave her away. "A century would be much too long to wait," she breathed. "Another five minutes would be too long. If it's going to collapse, I'd rather find out right now." I nodded and we started down. Several other passengers had emerged from the port and were looking up at the sky or downward as I'd done. Three men and a woman had emerged ahead of us and were almost at the base of the spiral. So far nothing had happened to them.