The phenomenon of the world's end--for nothing else describes it adequately--now appeared distinctly as a jagged line, beyond which nothing showed. It differed from the horizon line, inasmuch as it was close at hand. Already the adventurers could peer down upon it at an acute angle.
Plainly could they see the outlines of trees growing along the verge. But beyond them, nothing.
It differed essentially from a cañon, because there was no other side at all. Strain his eye as he might, Stern could detect no opposite wall. And now, realizing something of the possibilities of such a chasm, he swung the Pauillac southward. Flying parallel to the edge of this tremendous barrier, he sought to solve the mystery of its true nature.
“If I go higher, perhaps I may be able to get some notion of it,” thought he, and swinging up-wind, he spiraled till the barometer showed he had gained another thousand feet.
But even this additional view profited him nothing. Half a mile to westward the ragged tree-line still showed as before, with vacancy behind it, and as far as Stern could see to north, to south, it stretched away till the dim blue of distance swallowed it. Yet, straight across the gulf, no land appeared. Only the sky itself was visible there, as calm and as unbroken as in the zenith, yet extending far below where the horizon-line should have been--down, in fact, to where the tree-line cut it off from Stern's vision.
The effect was precisely that of coming to the edge of a vast plain, beyond which nothing lay, save space, and peering over.
“The end of the world, indeed!” thought the engineer, despite himself. “But what can it mean? What can have happened to the sphere to have changed it like this? Good Heavens, what a marvel--what a catastrophe!”
Determined at all hazards to know more of this titanic break or “fault,” or whatsoever it might be, he banked again, and now, on a descending slant, veered down toward the lip of the chasm.
“Going out over it?” cried Beatrice.
He nodded.
“It may be miles deep!”
“You can't get killed any deader falling a hundred miles than you can a hundred feet!” he shouted back, above the droning racket of the motor.
And with a fresh grip on the wheel, head well forward, every sense alert and keen to meet whatever conditions might arise, to battle with cross-currents, “air-holes,” or any other vortices swirling up out of those unknown depths, he skimmed the Pauillac fair toward the lip of the monstrous vacancy.
Now as they rushed almost above the verge he could see conclusively they were not dealing here with a cañon like the Yosemite or like any other he had ever seen or heard of in the old days.
There was positively no bottom to the terrific thing!
Just a sheer edge and beyond that--nothing.
Nowhere any sign of an opposite bank; nowhere the faintest trace of land. Far, far below, even a few faint clouds showed floating there as if in mid-heaven.
The effect was ghastly, unnerving and altogether terrible. Not that Stern feared height. No, it was the unreality of the experience, the inexplicable character of this yawning edge of the world that almost overcame him.
Only by a strong exercise of will-power could he hold the biplane to her course. His every instinct was to veer, to retreat back to solid earth, and land somewhere, and once more, at all hazards, get the contact of reality.
But Stern resisted all these impulses, and now already had driven the Pauillac right to the lip of the vast nothingness.
Now they were over!
“My God!” he cried, stunned by the realization of this thing. “Sheer space! No bottom anywhere!”
For all at once they had shot, as it were, out into a void which seemed to hold no connection at all with the earth they now were quitting.
Stern caught a glimpse of the tall forest growing up to within a hundred yards of the edge, then of smaller trees, dwindling to bushes and grasses, and strange red sand that bordered the gap--sand and rocks, barren as though some up-draft from the void had killed off vegetable growth along the very brink.
Then all slid back and away. The red-ribbed wall of the great chasm, shattered and broken as by some inconceivable disaster, some cosmic cataclysm, fell away and away, downward, dimmer and more dim, until it faded gradually into a blue haze, then vanished utterly.
And there below lay nothingness--and nothingness stretched out in front to where the sight lost itself in pearly vapors that overdimmed the sky.
Beatrice glanced at Stern as the Pauillac sped true as an arrow in its flight, out into this strange and incomprehensible vacuity.
Just a shade paler now he seemed. Despite the keen wind, a glister of sweat-drops studded his forehead. His jaw was set, set hard; she could see the powerful maxillary muscles knotted there where the throat-cords met the angle of the bone. And she understood that, for the first time since their tremendous adventure had begun, the man felt shaken by this latest and greatest of all the mysteries they had been called upon to face.
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.
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.