They were joined very soon by Shepard, upon whose high boots snow was clinging to the very tops, and he said when Dick looked at him inquiringly:
"I see that you're an observer, Mr. Mason. Yes, I've been out on the mountainside. Colonel Winchester suggested it, and I was glad to do as he wished. It was difficult work in the snow, but Mr. Reed, our guide, was with me part of the time, and we climbed pretty high."
"Did you see anything?"
"No footsteps. That was impossible, because of the falling snow, but I think our friends, the enemy, are abroad in the mountains. The heavy snow may have kept them from coming much nearer to us than they are now."
"What makes you think so?"
Shepard smiled.
"We heard sounds, odd sounds," he replied.
"Were they made by a whistle?" Dick asked eagerly. Shepard smiled again.
"It was natural for you to ask that question, Mr. Mason," he replied, "but it was not a whistle. It was a deeper note, and it carried much farther, many times farther. Mr. Reed explained it to me. Somebody with powerful lungs was blowing on a cow's horn."
"I've heard 'em. They use 'em in the hills back of us at home. The sound will carry a tremendous distance on a still night like this. Do you think it was intended as a signal?"