“Let’s look inside the house,” remarked Frank. “Then we’ll try to arrange for following the robbers.”

When they entered the strong room it was to find it empty, just as the former superintendent had declared was the case. No sign of any treasure could be seen.

“Is this your hat?” asked Bob, picking the article in question up.

“Never saw it before,” answered Mr. Riley.

“Then it must have belonged to one of the thieves!” suggested the boy, examining the head gear.

“Just as likely as not,” agreed the deposed superintendent. “But that isn’t goin’ to help us find out who they are, and where they can be run across right now.”

“Perhaps not,” observed Bob, as he again examined the soft, felt hat, which was of a gray color, with a black band around the crown, the whole forming a combination that would have been fairly noticeable.

“There’s nearly an hour before dark sets in,” Frank observed, “and perhaps we might get a start. Suppose you hunt up the best all-round trailer in the camp, Mr. Riley, and fetch him along. Have you horses that could be used? We might want to travel some distance, especially if the trail heads toward the Mexican border.”

“All right, Frank,” replied the other, seeming to brighten up at the chance for doing something. “I’ll be back in a little while, and we’ll make a start. If you want to look for yourself, hike over to where you see the broken rocks in a heap. Right alongside you’ll find the tracks of the robbers. We’ll fetch all the horses along.”

So Mr. Riley hurried away to carry out his part of the plan; while Frank and Bob walked over to where the rocks lay, looking very much like a grave, in the valley where the Cherry Blossom mine was being worked.