"You overestimate me," he replied. "All I can do, for now, is to camp down here and try to figure the problem out--with your help. Whatever this thing is, it's evident it stands between us and our plan. Either Chicago lies on the other side--(provided, of course, as you say, that there is one)--or else it's been swallowed up, ages ago, by whatever catastrophe produced this yawning gulf. "In either event we've got to try to discover the truth, and act accordingly. But for now, there's nothing we can do. It's getting late already. We've had enough for one day, little girl. Come on, let's make the machine ready for the night, and camp down here and have a bite to eat. Perhaps by to-morrow we may know just what we're up against!" The moon had risen, flooding the world with spectral light, before the two adventurers had finished their meal. All during it they had kept an unusual silence. The presence of that terrible gulf, there not two hundred feet away to westward of them, imposed its awe upon their thoughts. And after the meal was done, by tacit understanding they refrained from trying to approach it or to peer over. Too great the risks by night. They spoke but little, and presently exhausted by the trying events of the day--sought sleep under the vanes of the Pauillac. But for an hour, tired as he was, the engineer lay thinking of the chasm, trying in vain to solve its problem or to understand how they were to follow any further the search for the ruins of Chicago, where fuel was to be had, or carry on the work of trying to find some living members of the human race. 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.