“All right, fellows,” said the young airman, “I guess the time has come when it is safe for you to know what you have called a great secret.”

“Yes, out with it, Dave,” urged Hiram, “I’ve been dying with curiosity ever since I got a hint that some big mystery was afoot.”

“It is less of a mystery than an important piece of professional work,” explained our hero. “I didn’t tell you about it at Washington, because I was in doubt myself. When we escaped that explosion at Chicago, I was afraid it would unnerve and worry you to have a dread and uncertainty on your mind. I really thought something was going to happen to us at Winnipeg. It didn’t. We’re ahead or out of range of the enemy now, I feel pretty certain. To sum it all up, I hardly think we will be interfered with again—at least this side of the first Coast station, Sitka.”

“No, it doesn’t look as if anybody would try to chase us through three thousand miles of wilderness,” remarked Elmer.

“Anyway, there has been no sign of it so far,” said Dave.

“Provided that tramp monoplane we noticed at Winnipeg isn’t sneaking around somewhere,” put in Hiram, quite seriously.

Dave smiled, and Elmer laughed outright, with the words:

“That was all fancy.”

“Was it?” protested Hiram, getting excited. “I tell you, that black-looking machine was after something. You two didn’t see it as many times as I did. There wasn’t an airman I questioned who recognized the machine. It was a tramp, a pirate, and you won’t convince me that it wasn’t hanging around purposely to make somebody trouble.”

“Well, we missed it, if it was the Comet they were after,” said Dave. “Now then, fellows.”