"Don't let it get away from you," advised Nat.
"No, I'm serious," went on the lanky youth. "I think these men have some strange beast or bird in captivity, and that it gets away from them at times. Maybe that's what happened here, and they had to fight to capture it again."
"Not so nonsensical, either," Jack hastened to say. "If it was an immense bird, like a big eagle, it would account for the noises we heard--at least, some of them."
"But there is no eagle large enough for men to ride on its back," objected Nat.
"Didn't we hear them call and speak about our camp fire? How could they see it unless they were up high in the air, on the back of some big bird?"
"They might have been on some point of the mountain above us," said Bony. "They could have the eagle, or whatever it was, tied by a cord."
"Yes," admitted Nat; "but I don't believe it's a bird."
"Me either," came from Sam. "But what is it?"
"Let's look at the marks a little more carefully," proposed Jack.
"Several men have been here, struggling with the--the--er--whatever it was," spoke Will. "See the different footprints."
That much was evident. In addition to the man with the mark on his shoes of the arrow in hobnails, there were tracks of several other individuals.
"And if this isn't the mark of a big bird's wing, I'll eat a pair of snowshoes!" exclaimed Nat suddenly. "Look here, fellows!"
They hurried to where he was. There in the snow was the unmistakable print of what seemed to be a wing of a great creature of the air.
"And here's another wing," added Sam a little later as he walked slowly over the level place. "But they're some distance apart."
"I should say so," agreed Jack. "Sixty feet, if they're an inch."
"But the marks are those of two wings, and they were made at the same time," went on Sam. "Look, you can see where the body comes between the wings. The bird was over on its back. That happened when they tried to secure it."
"But sixty feet," objected Nat. "There's no bird living with a spread of wings like that. It's out of the question."
"Here's the evidence," spoke Sam obstinately. "You can see for yourself."
"Sixty feet spread," murmured Jack. "It doesn't seem possible."
But there was no doubt but that the marks in the snow were those of wings, and, as Jack paced the distance from tip to tip, they proved to be over sixty feet apart.