The aeroplane was approaching the rope bridge when Mr. Appleton suddenly called out that he saw two men on horseback on the track beyond. In another moment he recognized them through his glass as the men of whom they were in pursuit. They were nearly a mile distant, entering a stretch of the gorge that was particularly rugged, and no doubt afforded plenty of cover. It had been prearranged that as soon as the men were sighted Bob should make a descent as near as possible ahead of them--that is, down-stream--but it was no surprise to Bob--indeed, it was only according to the ill-luck that seems to rule on such occasions--that no suitable landing place offered itself.

He remembered, however, that in flying downstream he had noticed, two or three miles above the bridge, a place where the valley widened sufficiently to allow the aeroplane to circle. He decided to fly direct to this spot, turn, follow the men, outstrip them, and land at a spot some distance down-stream, where a landing had seemed feasible. Lawrence suggested that he or his uncle should take a flying shot at the men as they passed above them, but Mr. Appleton would not consent.

"Punishment before trial won't do," he said.

By this time the fugitives had disappeared behind a sort of parapet of rock just above the bridge, which spanned the river at a height of twenty or thirty feet. On first sighting them, Bob had caused the aeroplane to descend until it was almost level with the bridge. As they came to it, Mr. Appleton rose in his seat behind the pilot, to see, if he could, the precise spot in which the fugitives had concealed themselves. He had just done so, and was leaning slightly to the right, when there came in rapid succession the crack, crack of two rifles. And then Lawrence, in the third seat, was horrified to see his uncle pitch forward, lose his grip on the stay he was clutching, and fall headlong into the river. It all happened so instantaneously that the boy had no time even to reach forward. He sprang up, almost over-balancing himself, but before he could stretch out his hand Mr. Appleton was whirling in mid-air.

At the moment of the accident Bob was made aware that something had happened by the lurch which the sudden loss of weight caused the aeroplane to give. A cry from Lawrence apprised him of the nature of the accident. For a few moments both the boys were dazed by the shock of their uncle's disappearance, so sudden, so unexpected, so terrifying. Bob had instinctively moved his controlling lever to counter-act the lurch. As soon as he knew what had happened, instinct again prompted him to bring the aeroplane round; but reason coming to his aid, he corrected the movement just in time to avoid dashing the plane against the rocky barrier on his left hand.

"Keep straight ahead!" shouted Lawrence in terror.

But before the words were out of his mouth the danger of a fatal smash was avoided. The aeroplane flew at full speed up-stream. In a few minutes it would reach the wider space where turning was possible. Only then could the direction of its flight be reversed, and the fate of Mr. Appleton be ascertained.

In their anxiety for their uncle, both the boys had now forgotten the very existence of the Kalmuck miscreants. It did not occur to them that in repassing the same spot on their flight down-stream they might be in danger from the same concealed marksmen. As the aeroplane turned, Lawrence called to his brother to descend still lower, so that they might the more easily see their uncle's body if he were still floating in the stream.

"If I see him, I'll dive in," he said. "You go on, land where you can, and come back to my help."

With his eyes fixed on the water below he was unconscious of anything but the swirling flood, and the intense strain of searching the surface as the aeroplane flashed by. Neither Bob nor Lawrence noticed the movements of the two Kalmucks. They, as soon as they had fired their shots, vaulted into the saddles of the horses that stood beneath a tall rock, and dashed at headlong speed along the track towards the bridge. The horses, urged by their riders, and terrified by the increasing sound of the aeroplane rushing swiftly behind them, took the bits in their teeth and galloped on, completely beyond control. They wheeled on to the bridge. At this moment the aeroplane was only about two hundred yards behind them, and Bob was intending to pass under the bridge. But the weight of the horses was too much for the frail and clumsy structure. It broke in the middle, and horses and riders plunged into the river. Bob had just time to move his elevator and skim over the confused mass of bridge, horses and men.