"They must be experts in the art of hiding," grumbled Bob, upon returning from a visit to the chief of police. "I was certain they would be rounded up before this."

"Guess they must have made a break for the tall timber," said Joe.

"Decided, maybe, it isn't just healthy around here," added Herb, with a grin.

And then, just when they had decided that Ca.s.sey and his gang had made a masterly getaway, the radio boys got on their trail once again.

That very evening, when tuning in for the concert, they caught another of those mysterious, stuttering messages in the unmistakable voice of Dan Ca.s.sey!

"Rice, rats, make hay," was the substance of this message, and the boys would have laughed if they had not been so dumbfounded.

"What do you know about that?" gasped Jimmy. "That old boy sure has his nerve with him."

"They're still hanging around here somewhere!" cried Bob excitedly.

"They've probably got a hiding place that even the police can't find."

"Oh, if we could only make sense of this!" exclaimed Herb, staring at the apparently senseless message which he had written down. "If we only had their code the whole thing would be simple."

"Oh, yes, if we only had a million dollars, we'd be millionaires!"

retorted Jimmy scornfully. "Where do you get that stuff, anyway?"

"Well," said Bob, temporarily giving up the problem, "as far as I can see, all there is for us to do is to keep our eyes and ears open and trust to luck. Now what do you say we listen in on the concert for a little while?"

In the days that followed Ca.s.sey's voice came to them several times out of the ether, and always in that same cryptic form that, try as they would, they could not make out.

It was exasperating, that familiar voice coming to them out of the air day after day without giving them the slightest clue to the whereabouts of the speaker.

And then, while they were in town one day, they quite unexpectedly ran into their old friend, Frank Brandon, the wireless inspector, whose work for some time had taken him into another district.

However, he was to stay in Clintonia for a few days on business now, and since he had nothing particular to do that day, Bob enthusiastically invited him up to his home for a visit.

"Maybe you can give us some tips on our set," Bob added, as Mr. Brandon readily accepted the invitation. "We're not altogether satisfied with our batteries. For some reason or other they burn out too quickly."

"Yes, I'll take a look at it," agreed Mr. Brandon good-naturedly.

"Although I imagine you boys are such experts by this time I can't tell you very much. What have you been doing with yourselves since we last met?"

The boys told him something of their experiences, in which he showed intense interest, and in return he told them some interesting things that had happened to him.

And when he spoke of catching mysterious messages in the stuttering voice of Dan Ca.s.sey, Bob broke in upon him eagerly.

"We've caught a good many such messages too," he said. "Have you managed to make anything of them?"

"Not a thing," said Mr. Brandon, shaking his head. "If it is a criminal code, and I am about a.s.sured that it is, then it is a remarkably clever one and one that it is almost impossible to decipher without a key. I've just about given up trying."

Then the boys told of their encounter with Ca.s.sey in the woods and their adventure in the old barn, and Frank Brandon was immensely excited.

"By Jove," he said, "the man is up to his old tricks again! I'd like to get hold of him before he does any serious harm. That sort of criminal is a menace to the community.

"The funny part of it," he continued, as they turned the corner into Bob's block, "is that these messages are not all in Ca.s.sey's voice. Have you noticed that?"

It was the boys' turn to be surprised.

"That's a new one on us," Bob confessed. "The only messages we have caught so far have been in Ca.s.sey's voice."

Frank Brandon slowly shook his head.

"No," he said, "I have caught a couple in a strange voice, a voice I never heard before."

"The same kind of message?" asked Herb eagerly.

"The same kind of message," Brandon affirmed. "I have taken it for granted that the owner of the strange voice is a confederate of Ca.s.sey's."

"Maybe one of the fellows who was with him in the woods," said Jimmy, and Mr. Brandon nodded gravely.

"It's possible," he said. "I don't know, of course, but I imagine that there are several in Ca.s.sey's gang."

By this time they had reached Bob's home, and as it was nearly lunch time, Mrs. Layton insisted that they all stay to lunch. The boys, not liking to make her trouble, said they would go home and come back later, but the lady of the house would have none of it.

"Sit down, all of you," she commanded, in her cheerful, hospitable way.

"I know you're starved--all but Jimmy--" this last with a smile, "and there's plenty to eat."

Frank Brandon was very entertaining all during the meal and kept them in gales of laughter. Mrs. Layton found him as amusing as did the boys.

At last the lunch came to an end and Mr. Brandon professed himself ready to talk shop.

He was enthusiastic over the radio set the boys showed him and declared that he could see very little improvement to suggest.

"You surely have kept up with the march," he said admiringly. "You have pretty nearly all the latest appliances, haven't you? Good work, boys.

Keep it up and you'll be experts in earnest."

"If we could only find some way to lengthen the life of our storage batteries," said Bob, not without a pardonable touch of pride, "we wouldn't have much to complain about. But that battery does puzzle us."

"Keep your battery filled with water and see if it doesn't last you about twice as long," suggested the radio expert. "Don't add any acid to your battery, for it's only the water that evaporates."

"Will that really do the trick?" asked Joe, wondering. "I don't just see how----"

"It does just the same," Brandon interrupted confidently. "All you have to do is to try it to find out. Don't use ordinary water though. It needs to be distilled."

"That's a new one on me, all right," said Bob, adding gratefully: "But we're obliged for the information. If distilled water will lengthen the life of our battery, then distilled water it shall have."

"It seems queer," said Mr. Brandon reflectively, "how apparently simple things will work immense improvement. Marconi, for instance, by merely shortening his wave length, is discovering wonderful things. We cannot even begin to calculate what marvelous things are in store for us when we begin to send out radio waves of a few centimeters, perhaps less. We have not yet explored the low wave lengths, and when we do I believe we are in for some great surprises."

"Go on," said Joe, as he paused. "Tell us more about these low wave lengths."

CHAPTER XIV