"I wonder who those men were, and what they were after," mused Jack. "There
wasn't enough valuable stuff in the express packages to make four men risk
state's prison for it. It must have been the mail they were after. And
nothing of great value was in the mail, except the letters for Mr. Argent.
Of course, they were what they wanted. And in that case he ought to know
who would be most interested in taking them. We may be able to arrest the
men yet.

"But it may be too late," Jack reflected. "They may get the information
they want and take the secret mine away from those to whom it belongs. That
would be too bad! But if my plan only works, and those fellows don't open
that bundle of papers, the letters may be safe yet. It was my best chance.
If I could only get loose!"

Again Jack struggled and squirmed, but the ropes would not give an inch.
Suddenly, as the young pony express rider was trying to work loose his
bonds, he felt a sharp pain in one hand, which was under him, behind his
back, pressing on the earth.

"Whew! Something cut me then!" Jack exclaimed. "Must be a knife one of the
men dropped. If I could only get at that and on a rope!"

Carefully he felt along on the ground, so as not to cut himself again. His
fingers touched something sharp.

"A piece of glass--part of a broken bottle," he murmured. "Well, it may be
as good as a knife, but I'll probably cut myself more in using it."

He managed to work himself down until he had a firm grip on the piece of