He saw the answer. He gave a cry and lurched to his feet, flinging his pack aside and plunging directly at the monster. The foot halted, quite fast on the uptake, and rotated its eye to cover him. It gathered itself, crashed down, an irresistible juggernaut. The earth jumped with its fury; but Tinnerman, running in an unexpected direction, had passed its arc. He halted directly under the main body of the quinquepedalian. If his guess were correct, it would be unable to reach him there. It would have to move--and he would move with it. Far above, the main body hovered, a black boulder suspended on toothpicks. Above that, he knew, the neck and head extended on into the sky. A head shaped like a pear--when its mouth was closed. The first foot turned inward, its eye bearing on him. It hung there, several feet above the ground, studying him with disquieting intelligence. It did not try to pin him. Balance, Tinnerman judged, was after all of paramount importance to a creature two hundred feet tall. If it lost its footing, the fall of its body would destroy it. So long as it kept three or four feet correctly positioned and firmly planted, it could not fall; but if it were to pull its members into too small a circle it could get into serious trouble. Several hundred tons are not lightly tossed about. * * * * * The quinquepedalian moved. The feet swung clockwise, one at a time, striking the ground with an elephantine touch. The bars of Tinnerman's cage lifted and fell, crushing the terrain with an almost musical beat; the body turned, gaining momentum. The feet on one side seemed to retreat; on the other they advanced, forcing him to walk rapidly to keep himself centered. The pace increased. Now the feet landed just seconds apart, spinning the vast body forward. Tinnerman had to break into a run. Small trees impeded his progress; every time he dodged around an obstruction, the hind feet gained. On an open plain he might have been able to outrun the monster; but now it had maneuvered him onto rough ground. If it didn't tire soon, it would have him. In time it could force him over a cliff that its own legs could straddle, or into a bog. Or it might forget him and go after Abel--and he would have to stay under it, not daring to place himself outside its circle. His respect for it mounted; he was in the eye of a hurricane, and would soon have to find some other place of safety. Tinnerman studied the pattern of motion. At this velocity, the individual feet did not have time for more than peremptory adjustments; the maintenance of forward motion dictated an involved but predictable pattern. One foot had to vacate the spot for the next; he was not sure whether two feet ever left the ground at the same time, but could see sharp limitations. If he were to cross a print just vacated--