Already the verge lay far behind; and now the sense of empty space above and on all sides and there below was overpowering.
Stern gasped with a peculiar choking sound. Then all at once, throwing the front steering plane at an angle, he brought the machine about and headed for the distant land.
He spoke no word, nor did she; but they both swept the edge of the chasm with anxious eyes, seeking a place to light.
It was with tremendous relief that they both saw the solid earth once more below them. And when, five minutes later, having chosen a clear and sand-barren on the verge, some two miles southward along the abyss, Stern brought the machine to earth, they felt a gratitude and a relief not to be voiced in words.
"By Jove!" exclaimed the man, lifting Beatrice from the seat, "if that isn't enough to shake a man's nerve and upset all his ideas, geological or otherwise, I'd like to know what is!"
"Going to try to cross it?" she asked anxiously; "that is, if there is any other side? I know, of course, that if there is you'll find out, some way or other!"
"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.