"Looks to me as though you fellows knew something," he remarked. "I might have known if there was anything going on in the radio line within fifty miles of where you are that you'd know something about it."

"Well, I've got a hunch that we could lead you right to the place you're looking for," said Bob quietly.

"What?" shouted Brandon, leaping excitedly to his feet. "Do you really mean that? Tell me all about it."

For the second time that evening Bob recounted the happenings of their eventful excursion, while the radio inspector listened intently, throwing in a question here and there. When Bob had finished he made no comment for a few minutes.

Then he took the copy of the code and examined it intently, jotting down phrases here and there in his own notebook.

"Well," he said at length, "this looks to be a much bigger thing than I had supposed. Of course I heard of the robbery of the motor-truck, but I never for a moment connected that with this sending station we've been looking for. It seems fairly evident, though, that if we can lay our hands on the operators of the unauthorized sending outfit, we'll also have the perpetrators of that hold-up. This is a case where we'll have to think out every move before we act."

"Just before you arrived I was considering the advisability of putting the matter into the hands of the police," said Mr. Fennington. "What would you do?"

"Keep the whole thing to ourselves for the present," said Mr. Brandon decisively. "I'll send for a couple of good men to come up here and help me, and we'll keep a watch on that cabin for a few days. If this thing got into the papers, it would put the crooks on their guard, and probably spoil our chances of catching them and getting back the loot.

I've got a small but extremely efficient receiving and sending set in my car, and if any more code messages are sent out we'll catch them."

His confidence was contagious, and the boys felt almost as though the capture of the criminals had already been accomplished.

"What puzzles me, though," remarked Mr. Fennington, "is how you knew that there was an unauthorized radio sending station in this neighborhood, Mr. Brandon. I should think it would be almost impossible to locate such a station, even approximately."

"On the contrary," replied Frank Brandon, "it is little more than a matter of routine. Probably any of these radio fiends here could explain the method as well as I can, but I'll try to make it plain to you.

"There is a certain type of aerial that has what we call 'directional'

properties, that is, when it is shifted around, the incoming signals will be loudest when this loop aerial, as it is called, is directly in line with the sending station. The receiving antenna is wound on a square frame, and when the signals are received at their maximum strength, we know that the frame is in a practically straight line with the sending station we're after."

"Yes, but that still leaves you in the dark as to whether the station is one mile away or a hundred miles," observed Mr. Fennington, as Brandon paused.

"That's very true," answered the other. "And for that reason we can't stop at using just one loop aerial. What we actually do is to have three stations, each one equipped with a loop. These three stations are located a good many miles apart. Now, with these three loops, we have three lines of direction. We lay out these lines on a chart of the territory, and where they intersect, is the place where the unlicensed station is located. Is that clear?"

"Perfectly," said Mr. Fennington. "But what looks like a point on the map may be a large s.p.a.ce on the actual territory."

"Oh, yes, our work isn't done by any means after we have got our first rough bearings," continued Brandon. "Having determined the approximate position, we take the loops and receivers to what we know is a place quite near the station we're after, and then we repeat the former process. This time it is much more accurate. Gradually we draw the net tighter until we find the antenna belonging to the offender, and then--well, we make him wish he hadn't tried to fool the government."

"You certainly have it reduced to an exact science," acknowledged Mr.

Fennington. "I don't wonder that everybody interested in radio gets to be a fanatic."

"We'll make a 'bug' out of you before we get through, Dad," declared Herb, grinning.

"If my load of silk is recovered through the agency of radio, I'll be enthusiastic enough over it to suit even you fellows," said his father.

"It will mean the best set that money can buy for you if I get it back."

"We'll hold you to that promise," threatened Herb. "Radio can do anything," he added, with the conviction of a devotee.

"Well, pretty nearly everything," qualified Mr. Brandon. "A little while ago it was considered marvelous that we could transmit the voice by radio, and now the transmission of photographs by radio has been successfully accomplished."

"What!" exclaimed Mr. Fennington incredulously. "Do you mean to say that an actual recognizable photograph has been sent through the air by radio? That seems almost too much to believe."

"Nevertheless, it has been done," insisted Frank Brandon. "I saw the actual reproduction of one that had been sent from Italy to New York by the wireless route, and while I can't claim that it was perfect, still it was as plain as the average newspaper picture. And don't forget that this is a new phase of the game, and is not past the experimental stage yet."

"Well, after that, I am inclined to agree with Herbert that 'radio can do anything,'" admitted Mr. Fennington.

"I don't think we'll have much trouble making a convert of you," laughed the radio inspector. "No doubt the quickest way, though, will be to recover your stolen shipment, so we'll start working in that direction the first thing in the morning."

And in this he was as good as his word. He was up betimes, getting in touch with headquarters by means of his compact portable outfit. He kept at work until he had received the promise of two trustworthy men, who were to report to him at the lumber camp as soon as they could get there. Then he routed out the radio boys, and after a hasty breakfast they all set out to locate the cabin where the boys had found the code key.

CHAPTER XXI

THE GLIMPSE THROUGH THE WINDOW

The sun was just climbing above the treetops when the radio boys and Frank Brandon set out over the forest road, to the accompaniment of a full chorus of l.u.s.ty feathered singers. Robin and starling and thrush combined to make the dewy morning gladsome, and the boys whistled back at them and wished Larry Bartlett were there to learn some new notes.

"This would be just his dish," commented Herb. "After he got warmed up, you wouldn't be able to tell him from the birds."

"The only difference is, that he's better," declared Joe. "If he were here now, he'd be teaching the d.i.c.ky birds a new song or two. That boy is certainly a wonder."

"He's very clever," acknowledged Brandon. "He's getting along wonderfully well at the broadcasting station, and I understand he's had several good offers from the big vaudeville circuits."

"Why doesn't he accept one?" questioned Joe.

"He hasn't fully recovered from the effects of the accident yet. And, besides, he says he likes the radio work better. He can stay in one place, and cut out all the traveling. That seems to be a strong consideration with him."

"I don't know that I can blame him," commented Bob. "I should think that continual jumping around from place to place would get on anybody's nerves."

"Still, it gives one a fine chance to see the country," argued Frank Brandon. "If any of you fellows ever get into radio work in a commercial way, the chances are you won't be able to 'stay put' in one place very long."

"There's one great advantage about traveling, anyway," said Jimmy.

"What's that, Doughnuts?" queried Joe. "I should think that with your restful nature you'd rather stay in the same place and grow old and fat in perfect comfort."

"Oh, that part of it is all right," admitted Jimmy. "But don't forget that different parts of the country have different kinds of cooking. In New York the specialty is sh.o.r.e dinners; go a little South, and you get fried chicken and corn pone cooked by guaranteed southern mammies; go up North, and you get venison steaks; in the West they'll feed you mutton chops as big as a plate. And so it goes."

"You've even forgotten some places," laughed Bob. "How about a steaming dish of beans in Boston?"

"Yes, or frijoles and chile con carne in New Mexico," suggested Herb.

"Cease, cease!" groaned Jimmy. "Why talk about such things when we're such a long way from them? Every time you mention something new it makes me feel hungrier."

"Hungrier!" exclaimed Mr. Brandon. "Why, it's hardly half an hour since we finished breakfast!"

"What has breakfast got to do with it?" demanded the insatiable Jimmy.

"That's past and done with. It's time to think of lunch, now."

"You win," laughed Brandon. "Your capacity will make you famous some day."

"It's made him famous already--at least, up here," Bob informed the radio inspector. "Didn't you know that he is the undisputed champion pie eater of the camp?"