He dismissed the possibility from his mind. He was clothed now, fully clothed, and ready to depart. He started moving toward the airlock, feeling and looking like a giant beetle of the tropics, feeling awkward, cumbersome and insecure. His boots were weighted, and the bulge of the oxygen tank on his shoulder made him look almost hunchbacked in the cold light glimmer that turned the bulkhead into a mirroring surface as he advanced. He manipulated the airlock and it opened with a slow, steady droning and then he was passing through it, still moving awkwardly.... At last! He was out on the Martian desert in bright sunlight, staring up at the clear blue sky. The first few miles were not difficult at all. He walked away from the ship with his shoulders held straight, the cumbersome feeling dissipated by the lightness of his stride in the incredibly light gravity. The air pressure about him was less than seventy millimeters of mercury. The thought sprouted in his mind that he was the god Mercury striding along with winged shoes, and for the first five miles his weighted boots did seem to develop wings. Then the temperature began slowly to drop. The sun sank lower. Its brightness diminished, and his cheeks began to tingle with the cold. There was a slight wind blowing over the desert, raising dust flurries on the summits of the tallest dunes, causing the gray patches of crust lichen, which were scattered widely over the plain, to change color as their threadlike surfaces were ruffled by the breeze. Far in the distance he could see a "canal," one of those strange blue-green declivities in the terrain which looked from the air like an actual waterway, and had deceived--or bewildered--three generations of men. Despite the increasing cold, Corriston did not moderate his stride. He let his thoughts dwell on the most imaginative of the canal speculations. It had been proven completely false, but its originality fascinated him. Long ago, the theory held, there had been volcanic activity on Mars. Great faults or fissures had opened up in the planet's crust, and when the coming of spring thawed the polar ice caps, curtains of fog swirled equatorward, filling those natural crevices with swirling rivers of mist. Corriston stopped walking for a moment, shifting the weight of his equipment slightly, easing a too heavy drag on his right shoulder. He made sure that the thin flexible tube which connected his oxygen mask with the small tank on his back was securely clipped into place at both ends, tested the harness buckle which supported supplies which were as necessary to him as breathing, and took a turn up and down the sand, stamping, shaking himself, to make absolutely certain that nothing vital had been jarred loose.