“Me, too,” chimed in Jim. “No one’s talking to him, he’s just nutty and chins to himself.”

“Well, then, we have all the more reason for finding him,” said Tom. “If he’s really crazy the authorities ought to know it. Now we know he’s so close we ought to be able to locate him.”

So, day after day, the boys, their interest and enthusiasm at high pitch owing to the success of their experiments, shifted their instruments from house to house, gradually drawing their radio net about the mysterious sender until they were positive that he was located in a certain block, a district

of small, old-fashioned buildings, warehouses and garages.

But beyond this they could not go. There were no boys so far as they knew within the area and, satisfied that they had done all they could and that they had proved the value of their loops in locating the unknown speaker, all but Tom, Frank and Henry lost interest and devoted their attention to other matters.

But Tom, Frank, and, to a lesser degree, Henry were still deeply interested in the mysterious messages and were convinced that they came either from a gang of rum-runners or from some other law-breakers, for while there was nothing really suspicious in the messages they could not rid themselves of the idea, once it had entered their minds.

“I vote we go and tell Mr. Henderson all we know,” said Tom. “Dad won’t be back for two weeks or more yet and if Mr. Henderson thinks there’s anything in it he can have that block searched and find out who owns the set.”

“Well, perhaps ’twould be a good plan,” admitted Frank, and accordingly the two boys went to Mr.

Henderson’s office and related the story of their experiments and told of their suspicions.

“H-m-m,” remarked the keen-eyed man when they had ended, “this is very interesting, boys. Let me see the notes you made.”