“Well,” said Jack, “there’s only one thing more.”

“What is that?” asked Frank.

“Why, I’d like to know whom Rollins radioed to last night.”

“I found that out, too,” said Mr. Temple.  “He was talking to the Calomares ranch in Old Mexico, which has a very powerful station, according to Rollins.  He says the German, Von Arnheim, told him that there are similar powerful radio stations scattered throughout Mexico and South America, all built by German money for the use of its spy system.  And he said this German told him the most powerful station of all was on an island in the Caribbean, and that it was so powerful it could communicate with Nauen, Germany.”

It was apparent that Mr. Temple had concluded his explanation, and Bob and Frank began to ply him with questions.  Jack, however, stood silent, his face averted.  Mr. Temple presently broke from the others and laying a hand on Jack’s shoulder whirled him about.

“Father?” asked he, in a kindly tone.

“Yes, sir.”

“Well, Jack, I’ve got the beginnings of a plan in mind.  But first I must get more information from Rollins.  Then I’ll talk to you again.”

Jack looked him squarely in the face.

“Mr. Temple,” said he firmly, “I’m desperate.  Father is everything in the world to me.  I’ll wait to talk with you.  But I tell you frankly the only plan that appeals to me is to ride into Old Mexico and rescue him.”

The eyes of Bob and Frank, who had turned to listen, lighted up, and they nodded vigorous approval.  Mr. Temple stood off and looked at the trio of husky fellows as if seeing them for the first time.

“Perhaps,” said he, “that is what you will soon be doing.”

CHAPTER XV

TO THE RESCUE

“I may be wrong,” said Mr. Temple, thoughtfully, “in giving my sanction to this plan to rescue Mr. Hampton.  But I do not believe so.  And, all things considered, it seems the best if not the only way out.

“I have been accustomed to regard you as mere boys, but the conduct of every one of you in our adventures lately shows me you are able to think and act for yourselves.  Yet I don’t know.  Jack, you and Frank are motherless.  But—­if anything happened to Bob—­his mother never would forgive me.”

“Say, Dad, forget it,” grumbled the big fellow to hide his emotion.  “I can take care of myself.”

His father’s eyes lighted approvingly as they surveyed his truly heroic frame.

“Yes, I guess you can,” he said.  “And you carry a cool head, too.  At any rate, I’ve given my approval.”

He smiled whimsically, then looked from one to another of the three eager young fellows.

“My daughter Delia was right,” he said.  “When I left home she said I was wrong to think of you any more as youngsters, and that the first thing I knew you would be making use of your wit and ingenuity to take care of me.  And now her words in a measure are coming true.”