his father. “I’ll be sending a good many official messages, I expect, and I can

get them all off together each day—say 7:45. How will that be?”

“That’ll be fine,” assented Tom. “I’ll be here at half-past seven every night listening. Say, Dad, do you suppose those smuggler fellows use radio?”

“Why, I don’t know; what made you ask?”

“Oh, I just happened to think of it,” replied Tom. “I guess your speaking of sending official messages and starting for Cuba and the Bahamas just put it in my head.”

“Well, if we don’t find how they’re getting liquor into the States by wholesale pretty quick, I’ll begin to think they’re sending the booze in by radio,” laughed Mr. Pauling. “It’s the most mysterious thing we’ve been up against yet. Can’t get a clue. Perhaps they are using radio to warn one another, or maybe they’re onto our codes. Suppose you keep track of any odd messages you hear, Tom. I don’t suppose there’s anything in it, but it will give you another interest and one never knows what may happen through chance or accident. Remember that coup I told you about that we made during the war—that meaningless message that

passed all the censors and that, by pure accident, led to the capture of the worst lot of German plotters in the country?”

But Frank had not heard the story and so, from radio, the conversation drifted to Mr. Pauling’s experiences as an officer of the Department of Justice during the war and from that to his present problem of tracing to its source the mysterious influx of liquor which was flooding New York and other ports despite every effort of the government to stop it.

It was on this work that he was leaving for the West Indies, and long after he and Mrs. Pauling had left the room, Tom and Frank remained, talking earnestly, and with boyish imagination discussing the possibilities of aiding the government through picking up some stray information from the air by means of their instruments.

“We ought to have better sets,” declared Tom. “These are all right for getting the broadcasted entertainments and spark signals, but we can’t get the long waves from the big stations. And we don’t always get farther than Arlington or Pittsburgh with this. Last night, we heard Balboa, but

the night before that we couldn’t get Havana. If we’re going to hear Dad from Nassau or Cuba we want a set we can depend upon.”

“I’ll tell you what we’ll do,” replied Frank. “Let’s put everything that we both have together and have a fine set here in your room. I’ll bring my stuff down and we can work together—have duplicate sets and everything—and I’ll just keep that little old set of mine so I can use it when I happen to be home.”

“That’s a good idea,” agreed Tom, “Dad’s so interested in our work I can spend a lot more money on instruments and he won’t mind and school will soon be over and we can devote all our time to it. Gosh, I bet we have the best sets of any boys in the whole of New York! Say, won’t it be great when we can hear messages from England and Germany and France?”

“Yes, and we want to get busy on a sending set too. It’s twice as much fun when we can talk to others as well as hear them. And say! my folks are going to Europe next month. If your mother and father don’t mind I could stay here with you.”

“That’s bully! Of course mother won’t mind

and Dad will be glad to have you,” declared Tom. “We’re not going any place this summer and so we can give all our vacation to radio. Say, we may make some big discovery or invention. I was reading the other day about how many things there are to be done in radio yet and the fellow that wrote it said he believed some of the big things would be discovered by boys or beginners accidentally.”

Mrs. Pauling was very glad to have Frank plan to stay with Tom while his parents were absent and for several days the two boys were busy packing up Frank’s radio outfits and carrying them to Tom’s house.

When at last everything was there the boys had a veritable treasure trove of materials, for Frank had not been stinted in the amount he could spend on good tools, supplies and instruments and, while he did not possess the mechanical or inventive ability of Tom, yet he was a very careful and painstaking worker and everything he had was of the best.

Tom, on the other hand, preferred to make everything himself and, although his father was willing to let him have any sum within reason to

carry on his radio work, he spent most of the money for tools and supplies and had built a number of special instruments which even Frank admitted were big improvements over ready-made devices. In addition, he had a very complete library of radio books as well as scrapbooks filled with clippings from the radio columns of the various newspapers and periodicals. Hence the two boys made most excellent partners for carrying on their experiments and building their sets. Fortunately, too, they were not the type of boys who soon become tired of a subject and take up one fad after another and, while they were both strong, red-blooded, out-of-door boys, always ready for the most strenuous games, long hikes or hunting and fishing, they found radio so much more fascinating than football, baseball or other sports that practically everything else had been abandoned.

CHAPTER II—MYSTERIOUS MESSAGES

For the next few days the boys were very busy perfecting their instruments and, when Mr. Pauling bade Tom and his mother good-by and sailed southward, Tom assured him that he would be able to pick up any messages he sent.

“Maybe I’ll surprise you by sending a message,” he declared. “I’m going to apply for a license next week and make a sending set. Of course it won’t be able to send clear to Cuba or Nassau, but freak messages do go long distances sometimes and anyway, I can get in touch with your ship before you reach port coming back.”

“Great!” exclaimed his father heartily. “And don’t forget about stray messages—you may help us out yet. I spoke to Henderson about your idea that the bootleggers were using radio and he says he should not be a bit surprised. They’re right up to date in their methods, you know.”

That evening, Tom and Frank hurried to their sets promptly at 7:30 accompanied by Mrs. Pauling who seemed as interested as the boys in the result of their first attempt to pick up a message intended for them. She was rather disappointed, however, when Tom clamped on his phones and told her she wouldn’t be able to hear anything.

“You see,” he explained, “if the message comes in, it will be just code signal—dots and dashes in International Morse—and wouldn’t mean anything to you and I might miss it if I used the loud speaker.”

Slowly the minutes slipped by. From out of the silent air came various sounds to the boys’ impatient ears—little buzzing dots and dashes from local stations; the faint sounds of a phonograph from some amateur’s radiophone; fragments of speech from a broadcasting station. Carefully the two waiting, expectant boys tuned their instruments, for they had taken the precaution of asking the wireless operator on the ship what wave length he used and with their sets tuned as nearly to this as possible they cut out the amateur senders with their short wave lengths and the broadcasting

stations with their evening entertainments on 360 meter waves and heard only the meaningless or uninteresting Morse messages passing from ships to shore or vice versa.

Over and over Tom and Frank glanced anxiously at the little nickel-plated clock ticking merrily on its shelf, until at last the