Morning found them revived and strengthened. Even before they made their fire or prepared their breakfast they were exploring along the edge of the gigantic cleft.
Going first to make sure no rock should crumble under the girl's tread, no danger threaten, Stern tested every foot of the way to the very edge of the sheer chasm.
"Slowly, now!" he cautioned, taking her hand. "We've got to be careful here. My God, what a drop!"
Awed, despite themselves, they stood there on a flat slab of schist that projected boldly over the void. Seen from this point, the immense nothingness opened out below them even more terrible than it had seemed from the biplane.
The fact is common knowledge that a height, viewed from a balloon or aeroplane, is always far less dizzying than from a lofty building or a monument. Giddiness vanishes when no solid support lies under the feet. This fact Stern and the girl appreciated to the full as they peered over the edge. Ten times more ominous and frightful the vast blue mystery beneath them now appeared than it had seemed before.
"Let's look sheer down," said the girl. "By lying flat and peering over, there can't be any danger."
"All right, but only on condition that I keep tight hold of you!"
Cautiously they lay down and worked their way to the edge. The engineer circled Beta's supple waist with his arm.
"Steady, now!" he warned. "When you feel giddy, let me know, and we'll go back."
The effect of the chasm, from the very edge of the rock, was terrifying. It was like nothing ever seen by human eyes. Peering down into the Grand Canyon of the Colorado would have been child's play beside it. For this was no question of looking down a half-mile, a mile, or even five, to some solid bottom.
Bottom there was none--nothing save dull purple haze, shifting vapors, and an unearthly dim light which seemed to radiate upward as though the sun's rays, reflected, were striving to beat up again.
"There must be miles and miles of air below us," said Stern, "to account for this curious light-effect. Air, of course, will eventually cut off the vision. Given a sufficiently thick layer, say a few hundred miles, it couldn't be seen through. So if there is a bottom to this place, be it one hundred or even five hundred miles down, of course we couldn't see it. All we could see would be the air, which would give this sort of blue effect."
"Yes; but in that case how can we see the sun, or the moon, or stars?"