The instant the boys recognized the long-awaited signals, Frank called Henry and notified him as agreed and, to their delight and satisfaction, the mysterious stranger continued to talk, evidently paying no heed to the seemingly innocent words of the boys, if indeed he had heard them.

As heretofore, much that was said meant nothing to the boys, but wisely they jotted every thing down nevertheless. However, both Tom and Frank were more puzzled than ever, for now that their minds were concentrated on the messages they suddenly realized that a true conversation, an interchange of messages, was going on, but, for some inexplicable reason, they could hear but one of the speakers. It was like listening to one individual talking to another over an ordinary telephone and the boys could merely guess at the words of the inaudible speaker.

“Yes, it’s all right,” came the words on the easily recognized short waves, “thirty-eight fifty seventy-seven; yes, that’s it. Still there. Gave them the ha, ha! Azalia. Can’t get anything on her. How about Colon? French Islands? Sure, they’re just about crazy. No, no fear of that. Good stuff. No, no rough stuff. Expect her at same place about the tenth. No, don’t hang around. Cleared the third. Fifteen seconds west. I’ll tell him. Good bottom. Good luck! Don’t worry, we’ll see to that. No risk. So long!”

As the conversation ceased Tom jumped up. “Gee!” he exclaimed. “That’s the most we’ve heard yet. I wonder if Henry got it.”

Hurrying to the telephone, he was about to call Henry when the bell tinkled. “Hello!”—came the greeting in Henry’s voice as Tom took down the receiver. “This is Henry. Say, did you get it?”

“You bet we did!” Tom assured him gleefully. “What did you make out? No, guess you’d better not tell over the phone. We’ll be down there right away.”

“He’s east of here,” declared Henry, when Tom and Frank reached his home.

“Golly, he must be in Brooklyn or out on the river!” exclaimed Tom. “What did you make out that he said?”

Henry showed them the message as he had jotted it down and which, with the exception of one or two words, was identical with what they had heard.

“I couldn’t catch some of the words,” explained Henry. “There was a funny sort of noise—like some one talking through a comb with paper on it,—the way we used to do when we were little kids—say, what’s it all about anyway?”

“We don’t know,” replied Frank. “Did you hear any one else talking or anything?”

“And, Henry, were the sounds weak or faint to you?” put in Tom.

“Only that queer sound I told you about. The words were fine and strong here.”

“Then he’s nearer here than he is to us,” announced Tom. “But I would like to know who the other fellow was and what he said and why the dickens we can’t hear him when we hear this chap. Couldn’t you make out any of the words that the fellow said—those that sounded like talking through a comb, I mean?”

“No, they were just a sort of buzzy mumble,” replied Henry.

“Well if he’s east of here it ought to be easy to locate him,” remarked Frank. “Do you know any fellows around here who have sets, Henry?”

“Sure there are lots of ’em,” Henry assured him. “Tom Fleming over at Bellevue has a dandy set and there’s ‘Pink’ Bradley down on 19th St., and Billy Fletcher up on Lexington Ave., and a whole crowd I don’t know.”

“Well, let’s try it out at Fleming’s place next, then,” cried Frank. “Do you s’pose you can see him to-morrow and tell him the scheme? And say, ask him if he’s heard the same talk.”

“I can phone over to him now—I guess he’s home,” said Henry, “but what’s back of all this? You fellows aren’t so keen just because you want to locate this fellow that’s been talking, I’ll bet.”

Tom hesitated, but in a moment his mind was made up.

“I suppose we might just as well tell you,” he said at last. “But it’s a secret and you’ll have to promise not to tell any one else.”

Henry readily agreed and Tom and Frank told him all they knew and what they suspected.

“Whew!” ejaculated Henry. “I shouldn’t be surprised if you’re right. I couldn’t see any sense to all that talk about boats and the West Indies and numbers, but I can now. I’ll bet those numbers were places out at sea—fifteen seconds west—and ‘Azalia’ may be the name of the ship. Say, won’t it be bully if we can find out something—radio detectives—Gee, that’s great!”

“Well, go on and call up Fleming,” said Frank. “Tell him to come over here.”

“He’s on the way now,” Henry announced when he returned to the room. “Are you fellows going to let him in on the bootlegger stuff?”

“Better not,” advised Tom. “If he’s heard the fellow talking we can tell him we’re just anxious to locate him. We can make a mystery out of not hearing the person that was talking back, you know.”

“It’s a mystery all right enough,” put in Frank. “If that other chap can hear him, why can’t we? There’s something mighty queer about it.”

“Search me,” replied Tom laconically. “Maybe he talks on a different wave length.”

“I never thought of that,” admitted Frank. “Say, next time they’re talking one of us will listen while the other tunes to try and pick up the other man.”

“And perhaps he’s in a different direction,” suggested Henry. “If he is of course we wouldn’t hear him with our loops pointed towards this fellow.”

“Of course!” agreed Tom. “We have been boobs. Just as like as not the one we didn’t hear is over to the west or the north and we were all listening to the southeast. Say, you’ve got sense, old man. Next time we hear this chap we’ll nab the other one, I bet. Hello! There’s the bell.”

Henry hurried from the room and returned presently, accompanied by another boy whom he introduced as Jim Fleming. Jim was undersized and round-shouldered with damp, reddish hair and big blue eyes behind horn-rimmed glasses. He had a most disconcerting manner of staring at one and constantly blinking and gulping—like a dying fish Frank declared later—and his hands and wrists seemed far too long for his sleeves. He was such a queer, gawky-looking chap that the boys could scarcely resist laughing, but before they had talked with him five minutes they had taken a great fancy to him and found he knew a lot about radio.

While the boys told him of their interest in the strange conversations, he stood listening, his long arms dangling at his sides, his big eyes blinking and his half-open mouth gulping spasmodically until Tom became absolutely fascinated watching him.

Mentally, Frank and Tom had dubbed him a “freak,” a “simp,” a “bookworm” and half a dozen far from complimentary names and they had expected to hear him speak “like a professor,” as Tom would have expressed it. Instead he uttered a yell like a wild Indian, danced an impromptu jig and to the boys’ amazement exclaimed:

“Hully Gee! So youse’s onto that boid too! Say, fellers, isn’t he the candy kid though? Spielin’ on that flapper wave an’ cannin’ his gab if youse ask his call. Say, that boid oughter be up to the flooey ward—he’s bughouse I’ll say, with all his ship talk and numbers jazzed up an’ chinnin’ to himself. Say, did youse ever hear a bloke talkin’ to him?”

“No, we never did,” replied Tom. “Did you?”

“Nix!” answered Jim. “That’s why I say he’s got rats in his garret—flooey I’ll say—” Then, suddenly dropping his slangy East Side expressions, he continued: “Say, he’s had me guessing, too. But I can tell you one thing. He’s west of my place—I’m over at Bellevue, you know—Dad’s stationed there—and that’ll bring him somewhere between East 27th St. and Gramercy Square.”

“But, how on earth do you know that?” queried Tom in surprise.

Jim grinned and blinked.

“Same way you found out he was east of here,” he replied. “You needn’t think you fellows have got any patent on a loop, I’ve been usin’ one for six months. Ed—he’s my brother—is ‘Sparks’ on a big liner and showed me about it. But honest, if that fellow isn’t crazy an’ talkin’ to himself, why don’t we get the other guy sometimes?”

“That’s the mystery to us,” said Frank. “We decided just before you came in that the other fellow must be sending on a different wave length or else was in some other direction. We were just planning to pick him up by one of us tuning and turning the loop while the others listened to this fellow, but if you hear this man west of your place that knocks one of our theories out. If the other chap was west you’d get him, too.”

“Yep, and ’tisn’t because he’s on a different length,” declared Jim. “Hully Gee, I’ve tuned everywhere from 1500 meters down trying to get him, and nothin’ doin’.”

“Didn’t you ever hear a funny sound like talking through a comb with paper on it?” asked Henry.

“Sure, sometimes I do,” admitted Jim, “but you can’t bring it in as chatter—I put it down to induction or somethin’—but Gee, come to think of it, it always does come in just right between this looney’s sentences.”

“I’ll bet ’tis the other fellow,” declared Henry. “Only if ’tis he’s got an awful wheeze in his throat or his transmitter’s cracked.”

“Well, let’s drop that and plan how we can locate this fellow we do hear,” suggested Frank.

“Yes, now we know he’s between your place and here we ought to find some place where we can set up a loop to the north and south,” said Tom.

“Sure, we can fix that,” declared Jim. “I’ve got a cousin that lives over on 23d St. and there’s a good scout named Lathrop over on 26th. We can take sets to their places and put ’em up. They haven’t anything but crystal sets, and most likely they’ll know other guys and by trying out at different places we can spot his hangout all right. But say, what are you fellows so keen about findin’ him for?”

“Oh, nothing except the fun of it,” replied Tom, trying to act and speak in a casual manner. “You see we’re just experimenting to find out what we can do with loop aËrials—call ourselves radio detectives—and we picked on this fellow because his messages seemed sort of mysterious and are so easily recognized.”

“Yea, I understand,” said Jim. “Say that’s a lulu of an idea—radio detectives. Well, I’ll bet we can detect this bughousey guy O. K.”

It was soon arranged that Jim was to see his cousin and that one of the boys’ loops would be set up in his home the following evening and that, while Jim and Frank listened there, Henry and Tom would be at their sets and would call out as soon as they heard the messages from the mysterious speaker. All was arranged, but to the boys’ intense chagrin not a sound came to any of them which remotely resembled the well-known voice and short wave lengths of the man they were striving to locate. But they were not discouraged, for they knew from past experience that they could not expect to hear him every night.

The following day was Saturday and the boys devoted their holiday to putting up a set in Lathrop’s home. They now had four loop aËrial sets ready to receive and located within a comparatively small area. They were sure that the station they were trying to find was within the few blocks between 20th and 27th Sts., but they were not at all sure whether it would be found to the east or west of Third Avenue. Moreover, as Jim pointed out, for all they knew he might be on 27th St. or 20th St. or even slightly north or south of one or the other, for he stated that his brother had told him that when close to a sending station the loop aËrial could not be depended upon to give very accurate directions and that only by taking cross bearings could a certain point be definitely located. This was exactly what the boys had in view, to take cross bearings, and then, by means of a map of the city, to locate the man or the station.

It may seem as if the boys were devoting a great deal of time and trouble to something of little importance, but they were, or at least Tom, Frank and Henry were, thoroughly convinced that the messages emanated from some one connected with a rum-running gang and they were as keen on finding his location and as interested as if they had been real detectives detailed to discover a fugitive from justice.

So on that Saturday night they sat at their various instruments, waiting expectantly and with high hopes. No one was stationed at Tom’s home, for, in order to provide two sets for the test, Tom’s and Frank’s had been dismantled and reinstalled at the houses of Jim’s cousin and of Paul Lathrop.

Henry was the first to pick up the sounds and instantly he hurried to the telephone and called Jim. But by the time he had Jim’s number the latter had also picked up the signals and had called the others, for Tom had not disturbed his transmission set and ordinary phoning was the only means of communicating with one another at the boys’ disposal. For some time Tom, at the 23d St. house, could not pick up the sounds, but at last, with his loop pointed to the northeast, they came clear. “Congratulations,” was the first word he heard, instantly followed by the queer buzzing sound which Henry had described. “Golly, ’tis just like some one talking through a comb,” was Tom’s mental comment and deeply interested and tremendously puzzled he strained his ears and mind striving to formulate words or meanings from the strange sounds. Once or twice he was sure that the sounds were words—he thought he could make out “last night” following a query of “When was it?” from the other speaker but, as he told the others later, it was like trying to hear what a mosquito was saying.

So intent was he on this that he quite forgot to jot down the plain words of the other speaker and did not realize it until the sounds ceased and the conversation was over.

But he knew that the others would have it and he had the direction, which was the main thing, and, a few minutes later all the boys were together and eagerly discussing the results of their experiment.

“He’s southeast of my set!” announced Frank, when Tom had told them what he had discovered. “That puts him in between the river front and Third Avenue and between 23d and 26th Sts.”

“Well, we’re getting him narrowed down to a few blocks now,” said Henry joyfully. “Say, what did you fellows make of the talk? Here’s my slip.”

The words that Henry had written down were as follows: “Everything O. K. Yes, haven’t an idea. Sure, Fritz told me about it. Must be careful. No, but price will drop. No use killing the goose, you know. Golden eggs is right. Not a chance in the world of their getting wise. Nonsense, no one else has anything like it. Amateurs. Oh, forget it. Well, let ’em guess, guesses don’t prove anything. Well, if they did they’d never find anything. Magnolia. Yes, same place thirty fifteen west. Oh, yes, the French stuff went like hot cakes. Sure, get all you can. Yes she cleared. Regards to Heinrich. Expect you the eighteenth. Don’t forget Magnolia. Good-by.”

“It’s just the same as I made it,” announced Frank.

“Same here,” said Jim. “Sufferin’ cats! Do you mean to say that nut isn’t bughouse now?”

“It does sound a bit crazy, I admit,” replied Tom. “Say, did any of you fellows try tuning to different wave lengths to see if any one else came in?”

“I did,” declared Frank, “but all I got was some one who said ‘for the love of Mike get off the air.’”

“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.”

For a time he examined the slips of paper bearing the various messages the boys had scribbled down and his forehead wrinkled in a frown of perplexity.

“It’s very indefinite,” he announced at last, half to himself, “but I agree with you that the whole matter has a suspicious appearance. Too bad you didn’t take down the earlier messages you heard. Now, let’s see. You say you have never heard the other party to the conversations and yet you have been listening in within a block of this chap. Very odd, yes, most extraordinary. There are several explanations that occur to me, however. For example, if they wished the conversation to be secret and unintelligible they might have arranged that one man was to talk through an ordinary phone and the other by radio. Or they might have arranged this because the second man had no sending set—exactly as you boys communicated with one another with only one transmission set among you.”

“Gee, but we are dumb-bells!” exclaimed Tom. “Why the dickens didn’t we think of that? Why we are doing the same thing ourselves. It was so simple we overlooked it.”

Mr. Henderson smiled. “That’s often the way,” he declared. “During the war a lot of messages passed our censors as perfectly innocent and harmless and yet they were of the utmost importance—they were so frank and simple we overshot the mark.”

“Yes, Dad told us about some of those,” said Tom.

“As I was saying,” went on Mr. Henderson, “if one man was talking over a telephone you would not have heard him under ordinary conditions, but it often happens that through capacity inductance a phone message may come in over a radio set. That might account for your occasionally hearing those sounds which you describe as resembling words coming through a paper-covered comb. Do you remember the conditions under which you heard those sounds? Were you near telephone receivers, touching any part of your sets or doing anything unusual?”

The boys thought deeply, trying to revisualize the conditions that had existed on the few occasions when they had heard the odd buzzing sounds.

“I’m not sure,” said Tom at last, “but it seems to me that when I heard them the first time—that time I was on 23d St., I was sitting close to the telephone receiver on the table—I’d just been called up by Jim and—yes, I am sure now, I remember distinctly—I had my hand touching the stand while I was listening to the messages. You see, I was half inclined to phone to the others to find out if they heard the sounds and I reached out to pick up the phone and then changed my mind—but sort of kept my hand there.”

“Then that’s solved, I think,” declared Mr. Henderson. “If you had taken down the phone receiver and had kept your hand upon it you would probably have heard the other speaker’s voice plainly.”

“Gosh, why didn’t we think of that!” interrupted Frank. “And come to think of it, the phone is on the same table with the radio set at Henry’s house.”

“Well, we’ve laid one ghost, we’ll assume,” went on Mr. Henderson, “but that does not solve the mystery of the other speaker nor does it eliminate the possibility that these fellows may be crooks. In our work, you know, we always assume that every suspect is guilty until we prove our theory wrong and so we’ll assume that your mysterious speaker is a crook until we find we’re mistaken. However, before I take any active steps I think it will be a good plan to try another test. Suppose you listen in for a few nights more and, as soon as you hear this fellow, take down your phone receivers and hold the instrument against your body or arm and see if you get the voice of the other chap. Let me know the results and then we can plan our next move.”

“Hurrah! Now we are real radio detectives working for the government!” cried Tom enthusiastically. “Do you really think they’re bootleggers?”

“I make it a point never to form a hard-and-fast opinion,” replied Mr. Henderson with a smile at the boys’ excitement. “However, I should not be in the least surprised if they are, and if so and we round them up, Uncle Sam will have to thank you boys. Go to it, boys! Perhaps we may have to organize a radio detective corps yet, and I’m not sure that boys may not be able to show us old hands a few tricks at our own game.”