Astounding Stories of Super-Science, August 1930

They had tuned out on the escalator rays, but continued on still invisible--for the disc hung above them in plain view and it would have been suicide to let themselves be seen. Even so, Kendrick soon began to have an uneasy feeling of being followed. He looked around from time to time, but could see nothing. Were some of those invisible little creatures on their trail? He said nothing to Marjorie of his anxiety, but presently she too began glancing backward uneasily, every few steps. "They are near us!" she said at length, in a whisper. "I can sense them." It was more than sense, they soon discovered. Little paddings became quite audible, and once or twice they saw the sand scuffed up, not twenty feet away, as though by a foot passing over it. Meanwhile they were climbing a rise of ground, broken by many small hummocks and dotted with thorny shrubs. On the other side, at the foot of a long down-slope, lay Ajo. Once they reached the summit, Kendrick felt sure they could outdistance their pursuers on the descent. Already, if his watch was right, the train was preparing to pull out. It would be a breathless dash, but he was confident they could make it. So he reassured Marjorie as best he could, and helped her on up the slope. They were practically on the summit and already in view of the little railroad station and huddle of shacks below--when suddenly he felt himself tripped and flung violently to the ground. At the same instant, his companion emitted a scream, as she felt herself seized by invisible hands.