The monoplane headed downward at high speed, the wheels touched the ground, bumped back into the air, touched the ground again. The machine rolled ahead at fifty miles an hour, forty, thirty, and finally came to a stop dangerously near a large pile of stones.

“All out,” called Karl, when he had switched off the motor. “We’re here. And we came down without a smash-up.”

Directly across the river Almodena the adventurers could see Cuzco, looking strangely quaint in its pocket in the mountains.

“Here come more natives,” observed Mr. Holton, as a horde of twenty or thirty men, women, and children rushed toward the Americans.

As they came nearer, they uttered something that none of the newcomers understood.

“They’re speaking in Quichua—that’s the native tongue in this part of Peru,” explained Mr. Lewis. “It’s the same language that was used by the ancient Incas.”

Although the natives scrutinized the airplane carefully, they were not bothersome, staring rather in awe at the great “bird” that had come mysteriously to their city.

Karl thought it best to have the craft guarded against possible marauders. But how he could secure a guard was a problem, since none of the Indians could understand English or Spanish. And the aviator knew not one word of Quichua.

“Suppose we take turns watching it,” suggested Mr. Holton. “I’ll take the first watch of, say, two hours. Bob, you can take the second, and so on until we can make some other arrangements.”