"We must not get too far from the mountain," the professor said. "If we cannot find some way of getting back over it, we must wait until 744U-21 sends us help."

"We may stay and see the nova," said 6W-438 grimly. "It will be a wonderful sight."

"A better way to die than those who were killed when our spaceship crashed. Doomsday on Ajiat will usher in a beautiful morning of flaming brilliance."

"Followed by a gloomy night of desolation and death."

The machine men walked slowly back in the direction of the mountain. Night fell. Still they kept on their way.

Their progress was forced. They knew that their mechanical parts would never stand the strain of climbing up the mountain. Their energies would soon be exhausted by the strain, parts would wear out, and they could neither be refueled nor repaired in the absence of the spaceship. They could only remain in a conspicuous and advantageous position near the mountain, waiting for the help they knew 744U-21 would send if they could be found.

Through the night, fire suddenly lit the sky ahead of them. There was first a dull, soft glow. This grew to towering proportions in a single, leaping flame. The fire was no farther than half a mile ahead of them, and soon they were able to distinguish black, shadowy forms which passed between them and the fire.

The professor called a halt. Several times they saw large fire brands carried. From the size of these, and the height at which they were carried, and from what they were able to see of the black shadows, the machine men knew the creatures to be veritable giants.

"Quite in keeping with this world," Professor Jameson observed. "It goes without saying that they are unusually strong. We shall do well to remain undiscovered."

With the coming of morning, the fears of the professor were justified. From afar, the machine men could see more distinctly the lofty, bulking figures which had been etched in silhouette against the campfires of the night before.