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 canyon 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.