The other made no answer.
"Look!" whispered Graham, crouched close, and became very still.
The snow had suddenly become thick again, and sliding with the whirling eddies out of the black pit of the sky came something, vague and large and very swift. It came down in a steep curve and swept round, wide wings extended and a trail of white condensing steam behind it, rose with an easy swiftness and went gliding up the air, swept horizontally forward in a wide curve, and vanished again in the steaming specks of snow. And, through the ribs of its body, Graham saw two little men, very minute and active, searching the snowy areas about him, as it seemed to him, with field glasses. For a second they were clear, then hazy through a thick whirl of snow, then small and distant, and in a minute they were gone.
"Now!" cried his companion. "Come!"
He pulled Graham's sleeve, and incontinently the two were running headlong down the arcade of ironwork beneath the wind-wheels. Graham, running blindly, collided with his leader, who had turned back on him suddenly. He found himself within a dozen yards of a black chasm. It extended as far as he could see right and left. It seemed to cut off their progress in either direction.
"Do as I do," whispered his guide. He lay down and crawled to the edge, thrust his head over and twisted until one leg hung. He seemed to feel for something with his foot, found it, and went sliding over the edge into the gulf. His head reappeared. "It is a ledge," he whispered. "In the dark all the way along. Do as I did."
Graham hesitated, went down upon all fours, crawled to the edge, and peered into a velvety blackness. For a sickly moment he had courage neither to go on nor retreat, then he sat and hung his leg down, felt his guide's hands pulling at him, had a horrible sensation of sliding
