Gone now was all sight of the land that they had left. Unlike balloonists who always see dense clouds or else the earth, they now saw nothing. All alone with the sun that rushed behind them in their skimming flight, they fled like wraiths across the emptiness of the great void.
Stern glanced at the barometer, and grunted with surprise.
“H'm! Twelve thousand four hundred and fifty feet--and I've been jockeying to come down at least five hundred feet already!” thought he. “How the devil can that be?”
The explanation came to him. But it surprised him almost as much as the noted fact.
“Must be one devil of a wind blowing up out of that place,” he pondered, “to carry us up nearly four thousand feet, when I've been trying to descend. Well, it's all right, anyhow--it all helps.”
He looked at the spinning anemometer. It registered a speed of ninety-seven miles an hour. Yet now that they were out of sight of any land, only the rush of the wind and the enormous vibration of the plane conveyed an idea of motion. They might as well have been hung in mid-space, like Mohammed's tomb, as have been rushing forward; there was no visible means of judging what their motion really might be.
“Unique experience in the history of mankind!” shouted Stern to the girl. “The world's invisible to us.”
She nodded and smiled back at him, her white teeth gleaming in the strange, bluish light that now enveloped them.
Stern, keenly attentive to the engine, advanced the spark another notch, and now the needle crept to 102 1/2.
“We'll be across before we know it,” thought he. “At this rate, I shouldn't be surprised to sight land any minute now.”