The Radio Boys At Mountain Pass, Allen Chapman, 1922, pages v - vi:
FOREWORD

BY  JACK  BINNS

    In the first chapter of this volume there appears a statement by "Bob," one of the Radio Boys, as follows: "Marconi is one of those fellows that can never rest satisfied with what's been done up to date."
    Perhaps no more concise summary of the driving force back of the men responsible for the tremendous development of radio could be made. It is just that refusal to be satisfied with what has been accomplished that has made wireless the greatest wonder development in the history of mankind.
    Although the radio boys in this case are but creatures of the author's imagination, nevertheless they are typical of all the men who have taken part in bringing radio to its present stage. Even Marconi himself likes to take pride in the assertion that he too was at one time an amateur, because he insists that during his early experiments he was only a boy amateur tinkering with a little known subject.
    There is undoubtedly a great deal of truth in his claim, because the experiments that led to his success were made while he was a youth studying at the Bologna University in Italy.
    What is true of Marconi is equally true of all the others. We have only to think of a name prominent in the field of wireless, and then trace back the history of the man who bears it, and you will come to an enthusiastic amateur.
    There is another fascinating thing about wireless, and it is the fact that no matter how much work one may really expend in tinkering with it, and no matter how valuable the results, it does not seem like real work. This is aptly phrased by Joe in the book who says:
    "I'd like to take it up as a regular profession. Think of what it must be for fellows like Armstrong and Edison, and De Forest and Marconi. I'll bet they don't think it's work."
    There is no doubt that Joe wins his bet.
Binns signature

Pages 10-13:
THE  RADIO  BOYS  AT  MOUNTAIN  PASS


CHAPTER  I


THE  BEAR  PERSUES


    "All the same," he protested, "Doc. Preston has been rushing us like the old Harry all this fall, and what with school work and home work and radio work."
    "Radio!" interrupted Bob. "You don't call that work, do you? Why it's fun, the greatest fun in the world."
    "You bet it is," chimed in Joe enthusiastically. "We never knew what real fun was until we took it up. Look at the adventures it's brought us."
    "I tell you, fellows, there's nothing like radio in the universe!" agreed Jimmy.
    "I'd like to take it up as a regular profession," said Joe. "Think of what it must be for fellows like Armstrong and Edison and De Forest and Marconi. I'll bet they don't think it's work. They're eager to get at it in the morning and sorry to knock off at night. There's no drudgery in a profession like that."
    "Speaking of Marconi, remarked Herb, "I see that he's just come over to America again on that yacht of his where he thought he heard signals that might have been from Mars. I wonder if he's heard any more of them."
    "I don't know," replied Bob thoughtfully. "Though I've become so used to what seem to be almost miracles that I'm prepared for almost anything. At any rate, the only thing one can do nowadays is to keep an open mind and not say beforehand that anything is impossible. It would be great, wouldn't it, if we could get in touch with another planet? And if we could with one, there doesn't seem to be any reason why we couldn't with all, that is if there's life and intelligence on them. But after all, at present that's only speculation. What interests me more just now is the discovery that Marconi is said to have made by which he is able to send out radio waves in one given direction."
    "I hadn't heard of that," remarked Joe. "I thought they spread out equally in all directions and that anybody who had a receiving set could take them."
    "So they have up to now," replied Bob. "But Marconi's one of those fellows that can never rest satisfied with what's been done up to date. That's what makes him great. I'm not exactly clear about this new idea of his, but the gist of it is that he throws a radio wave in a certain direction, much as a mirror throws a ray of light. He uses a reflector apparatus and the wave is caught at the receiving end on a horizontal metal standard. With a wave of only three and one half meters he has thrown a shaft nearly a hundred miles in just the direction he wanted it to go. The article I read said that he had some sort of semicircular reflector covered with wires that resembled a dish cut in half. When the open side is turned toward the receiving station he wants to reach, the signals are heard loud and clear. When the open part is turned away, the signals can't be heard. The whole idea is concentration. Just what a burning glass does with the rays of the sun, his device does with the radio waves. Marconi's a wizard, and that's all there is about it. There's no knowing what he may do next. But you can be sure that it'll be something new and valuable."
    "He's a wonder," agreed Joe heartily. "And if he's the 'father of wireless,' we've got to admit that he has a good healthy baby. I'm going to try to get on friendly terms with that baby."
Pages 50-55:

    Doctor Dale, the friend and counselor of the boys in radio, as in many other things, was in the pulpit. He was a very eloquent preacher and was always sure of a good congregation. But as Joe had said, the church was even fuller than usual that morning, and there was a general stir of expectancy, as though something unusual was in prospect.
    The attention of the boys was attracted at once by a small disk-like contrivance right in front of the preacher's desk. It had never been there before. They recognized it at once as a microphone, but to the majority of the audience its purpose was a complete mystery, and many curious glances were fixed upon it.
    There were the customary preliminary services, and then Doctor Dale came forward to the desk.
    "Before beginning my sermon this morning," he said, "I want to explain what will seem to some an unusual departure from custom, but which I hope will justify itself to such an extent as to become a regular feature of our service.
    "There is no reason why the benefits of that service should be confined to the persons gathered within these four walls. There are thousands outside who by the means of radio, that most wonderful invention of the present century, can hear every word of this service just as readily as you who are seated in the pews. The prayers, the hymns, the organ music, the sermon, the benediction--they can hear it all. The only thing they will miss will be the privilege of putting their money in the collection plate."
    He paused for a moment, and a smile rippled over the congregation.
    "I have said," he resumed, "that they can hear it. And if they can hear it, they ought to hear it--that is if they want to. This is no new or untried idea. It is being carried out to-day in Pittsburgh, Washington, and other cities. The pulpit becomes a religious broadcasting station, from which the service is carried over an area of hundreds of miles. Everybody within that area who has a receiving set can hear it if they wish. In some cases it is estimated that more than two hundred thousand people are enjoying at the same moment the same religious service. You can see at once what that means in immeasurably extending the usefulness and influence of the church.
    "Now it has occurred to me that we might do here what is being done elsewhere on a larger scale. So, after a conference with the officials of the church, an adequate sending set has been installed in the loft of the building. What is said here is sent from this microphone to the loft, where it is flung out into the ether. Arrangements have been made with a number of churches in this county, too poor and small to have a regular pastor by which they have installed loud speaker receiving sets in their buildings. At this moment there are a dozen scattered congregations where the people have gathered to worship, and where at this moment they are hearing everything that is said just as plainly as you do.
    "And in addition to that," he went on, "in hundreds, perhaps thousands of homes, people who cannot go to church because of illness or some other reason are listening to this service. The sick, the crippled, the blind--think of what it means to have the church brought to them when they cannot go to the church. You in the pews are the visible congregation. But outside these walls there is to-day an invisible congregation many times greater, to whom this service is bringing its message of help and healing."
    With this prelude, Doctor Dale announced his text and preached his sermon, which, if anything, was more eloquent than usual. It seemed as if he were inspired by preaching to the greatest audience that he had ever had in his whole career, and the audience in the pews also felt a thrill as they thought of the invisible listeners miles and miles away. It seemed as though the natural were being brought into close connection with the supernatural, and the impression produced was most powerful.
    If the doctor had had any misgivings as to the attitude of his people toward this new departure, these were quickly dissipated by the cordial congratulations and approval that were expressed after the service was over and he moved about among them. It was the universal opinion that a great advance had been made and that the innovation had come to stay.
    The radio boys had been intensely interested in this new application of their favorite study, and after the sermon they went up into the loft and examined the apparatus that had been used in sending. It was a vacuum tube set with two tubes and power enough to send messages out over the whole county. It had been set up by Dr. Dale himself, and that was proof enough for the boys that it had worked perfectly in sending out the morning service.
    "What will radio do next?" asked Bob, as the boys were walking homeward.
    "What won't it do next is the way you ought to put it," suggested Joe. "It seems as if there were no limit. There are no such things as space and distance any more. Radio has wiped them out completely."
    "That's true," chimed in Herb. "The earth used to be a monstrous big thing twenty-five thousand miles round. Now it's getting to be no bigger than an orange."
    "What a fuss they made when it was proved that one could travel around the world in eighty days," said Jimmy. "But radio can go round the earth more than seven times in a single second. Just about the time it takes to strike a match."
    "Gee, but I'm glad we weren't born a hundred years ago," remarked Bob. "What a lot of things we would have missed. Automobiles, locomotives, telegraph, telephone, phonograph, electric light----"
    "Yes," interrupted Joe, "and radio would have been the worst miss of all."
    "They're doing in the colleges now, too, something very like what the doctor did in the pulpit this morning," said Bob. "In Union College and Tufts and a lot of others the professors are giving their lectures by radio. Talk about University Extension courses! Radio will beat them all hollow. Think of a professor lecturing to an audience of fifty thousand, instead of the hundred or so that are gathered in his classroom. And think of the thousands of young fellows who are crazy to go to college and haven't the money to do it with. They can keep on working and get their college education at home. I tell you what, fellows, Mr. Brandon was right the other day when he said that the surface of radio had only been scratched so far."
Pages 69-71:

CHAPTER  VII

RADIO  WONDERS

    THAT day and the next were busy ones for the radio boys. The party was to go in two big automobiles that Mr. Layton had hired, and the boys had secured permission to take a small radio set with them. On the morning set for their departure they were ready to the last detail, and it was not long before they and their belongings were snugly packed into the two automobiles and they were all on their way to the mountain resort.
    Although it was still only mid-autumn, the air had a keen edge to it, the sky was gray and overcast, and there was the indefinable feel of snow in the air. The big cars rolled crisply through long drifts of dead leaves, going at a lively pace, as it was quite a journey to the resort, with many steep grades to be encountered on the way. The boys were warmly wrapped, and the keen air only gave zest and added to their high spirits.
    "These cars ought to be equipped with a radio set," remarked Bob, a short time after they had started. "I saw a picture the other day of a car that was rigged up that way, with an antenna from the radiator to a mast in the rear."
    "It's not a bad idea, at that," said Joe. "If a person were going on a long tour, he could keep in touch with the weather forecasts, and know just what to expect the next day."
    "Yes, and when he camped for lunch, he could have music while the coffee pot was boiling," said Herb. "Pretty soft, I'll say."
    "He'd be out of luck if the static were bad, though," observed Jimmy.
    "Oh, it won't be long before they'll get around that static nuisance," said Bob. "Have you heard of the latest method of overcoming it?"
    The others had not, and Bob proceeded to explain.
    "At Rocky Point, Long Island, they put up twelve radio towers, each four hundred and ten feet high, in a row three miles long. Then they hitched up a couple of two hundred kilowatt alternators so that they run in synchronism. That means four hundred kilowatts on the aerial, and I guess that can plough through the worst static that ever happened."
    "Four hundred kilowatts!" exclaimed Joe. "That's an awful lot of juice, Bob."
    "You bet it is," agreed Bob, nodding his head. "But it does the work. When they tested out this system signals were received in Nauen, Germany, of almost maximum strength, in spite of bad weather conditions. You know they have a numbered scale, running from nothing to ten, which is maximum. Well, the Rocky Point signals were classed as number nine, which means they were almost maximum strength."
    "It must have been a terrible job to synchronize those two alternators," commented Joe.
    "No doubt of it," agreed Bob. "This article stated that they had to experiment for months before they succeeded. Those machines turn over at somewhere around twenty-two thousand revolutions per minute, you know."
    "About three hundred and sixty-six times a second," said Joe, after a short mental calculation. "Nothing slow about that, is there?"
    "It's fast enough to do the trick, anyway," agreed Bob. "Wouldn't it be great to be in charge of a station like that?"
    The others agreed that it would, and for some time they discussed this latest marvel of radio.
aerial still up Pages 89-115:

Owing to the sickness in Clintonia, there had been an unprecedented rush of visitors to the hotel, and the Layton party discovered that they would have to take one of the small cottages adjoining the hotel, although they would board in the main establishment.
    The cottage was snug and comfortable, however, and they were all delighted with it. Indeed, it was better for the radio boys than rooms in the hotel, because they could set up their receiving set more readily. Of course, it was out of the question to erect an outdoor aerial, but they were not bothered by this and decided to use a loop aerial instead. They had brought with them a knock-down frame on which to wind their antenna, and this frame could be moved around and set against the wall when not in use.
    The first night at Mountain Pass they had little thought, however, even for their beloved radio, and were content to tumble into bed shortly after dinner. But the next day they were up early, and after a hearty breakfast set to work to put up their set.

CHAPTER  X

CONVINCING  A  SKEPTIC

    IT was a simple matter for the boys to wind the loop aerial, for they had become expert in the manipulation of wire, tape, and the numerous other accessories that go with the art of wireless telephony. After the aerial was completed they unpacked their receiving set and quickly connected it up. They worked skillfully and efficiently, and before the lunch bell rang at noon they were ready to receive signals.
    The boys wanted to get back to their radio set after dinner, but the snow looked so inviting that they could not resist the temptation to have a snow fight. They had had a good time, and they knew that there is seldom any fun that does not have its own drawbacks. They went to their rooms, changed the wettest of their clothing for dry articles, and were soon ready to test their set.
    They were just making a final inspection of their connections when Mr. Layton entered the room, accompanied by two other gentlemen.
    Mr. Layton introduced the two latter as the owners of the store he was thinking of purchasing.
    "Mr. Blackford and Mr. Robins are rather skeptical about radio," explained Mr. Layton, when the introductions had been duly accomplished. "I happened to mention it this morning, and as they both seemed to think I was exaggerating its possibilities, I asked them here to see and hear for themselves."
    "It's no trouble to show goods," said Bob, grinning. "We haven't tested for signals yet, but the set is all hooked up, and I guess all we'll have to do is tune up and get about anything you want."
    "You seem pretty confident," remarked one of the two strangers, Mr. Robins. "My opinion is, that this radio stuff is mostly bunk. A friend of mine bought a set just a little while ago, and he couldn't hear a thing with it. Paid fifteen dollars for it, too."
    "I shouldn't imagine he could," said Bob, drily. "Mountain Pass must be at least a hundred miles from the nearest broadcasting station, and that set you speak of could never be expected to catch anything more than twenty-five miles away, at the most."
    "Well, I'll bet dollars to doughnuts you can't hear anything with that outfit you've got there, either," broke in the other of the two strangers.
    "You'd lose your money, Blackford," said Bob's father. "Go ahead and convince these doubting Thomases, Bob."
    Bob adjusted a headset over his ears and switched on the current through the vacuum bulb filament. Then he manipulated the voltage of the "B," or high voltage, dry battery, and also varied the current flowing through the filament by means of a rheostat connected in series with it. Almost immediately he caught a far-away sound of music, and by manipulation of the variometer and condenser knobs gradually increased the strength of the sounds.
    Meantime Mr. Layton's two acquaintances had watched proceedings with open skepticism, and often glanced knowingly at each other. But suddenly, as Bob twisted the knob of the variable condenser, the music became so loud that all in the room could hear it, even though they had no receivers over their ears.
    "If either of you two gentlemen will put these receivers on, he'll be convinced that radio is no fake," said Bob quietly, at the same time removing his headset and holding it out.
    After a moment's hesitation Mr. Robins donned the receivers, and a startled look came over his face, replacing the incredulous expression it had worn heretofore.
    "Let's hook up another set of phones, Bob, and let Mr. Blackford listen at the same time," suggested Joe.
    This was done, and soon both skeptics were listening to their first radio concert. Mr. Layton regarded them with an amused smile. Mr. Robins extended his hand curiously toward the condenser knob, and immediately the music died away. He pulled his hand hastily away, and the sounds resumed their former volume.
    "Don't be frightened," laughed Mr. Layton. "It won't bite you."
    "But what made it fade away in that fashion?" asked Mr. Robins.
    "Don't ask me," said Bob's father. "I'm not up on radio the way the boys are. I enjoy it, without knowing much of the modus operandi."
    "That was caused by what is known as 'body capacity,' " explained Bob. "Every human being is more or less of a natural condenser, and when you get near the regular condenser in that set, it puts more capacity into the circuit, and interferes with its balance."
    The other nodded, although in reality he understood very little of even this simple explanation. He was too much absorbed in listening to what was going on in the phones.
    As he listened, he heard the latest stock market quotations given out, among them being the last minute prices of some shares he happened to be interested in. He slapped his knee enthusiastically, and when the last quotations had been given, he snatched off the headset and leaped to his feet.
    "I'm converted!" he fairly shouted. "I'll buy this outfit right as it stands for almost any price you fellows want to put on it. What will you sell it for?"
    The boys were taken aback by this unexpected offer, and all looked at Bob expectantly.
    "Why, we hadn't even thought of selling the set," he said slowly. "We wouldn't sell it right now, at any price, I think. But when we leave here to go back home, I suppose we might let you have it. How about it, fellows?"
    After some argument they agreed to this, but Mr. Robins was so determined to have the set that he would not be put off.
    "Now look here," he said. "I'm a business man, and I'll make you a business proposition. I'll buy that outfit right now, before I leave this room, at your own figure. But you fellows can keep it here and have the use of it just the same as you have now, only it will be understood that I'll have the privilege of coming over here once a day in time to hear those market reports. At the same time you can teach me something about operating the thing. How does that strike you?" and he threw himself back in his chair and waited for his answer.
    "We'll have to talk over that offer for a little while," said Bob. "Give us ten minutes or so, and we'll give you an answer."
    "That's all right," replied Mr. Robins. "While I'm waiting I'll just put on those ear pieces again and see what's doing."
    The radio boys left the room and held an excited conference downstairs. After some discussion they agreed to sell their set, as long as they could have the use of it during their stay at the resort, but the matter of price proved to be a knotty problem. Bob produced pencil and paper, and they figured the actual cost of the set to themselves, and then what the same set would have cost if bought ready made in a retail store.
    "The actual material in that set didn't cost us much over forty dollars, but we put a whole lot of time and experience into it," said Bob. "It would cost him close to a hundred to get as good a one in a store."
    "It's a mighty good set, too," said Joe, a note of regret in his voice. "We might make another as near like it as possible, and not get nearly as good results."
    "Oh, don't worry. We're some radio builders by this time," Herb reminded him. "Besides, that isn't the only set we've got."
    "Let's ask him eighty dollars," ventured Jimmy. "He'll be getting it cheaper then than he could buy it retail, and we'll be picking up a nice piece of change."
    "I think that ought to be about the right figure," agreed Bob. "Does that suit this board of directors? Eighty hard, round iron men?"
    The others grinned assent, and they returned to the room where the older men were still seated about the radio set.
    "Well, what's the verdict?" inquired Mr. Robins, glancing keenly from one to the other.
    "We've decided to sell," replied Bob. "The price will be eighty dollars."
    Without a word Mr. Robins produced a roll of greenbacks, and counted off the specified amount in crisp bills.
    "You'll want a receipt, won't you, Robins?" inquired Mr. Layton.
    "Not necessary," replied the other. "I've got a hunch that your son and his friends are on the level and won't try to cheat an old fellow like me. I'll have to be going now, but I'll be around about the same time to-morrow morning to get the stock quotations. Coming, Blackford?"

CHAPTER  XI

A  MOUNTAIN  RADIO  STATION

    LEFT to themselves, the boys looked at one another.
    "That's what I call quick work," remarked Joe. "I hate to let the old set go, but they say you should never mix sentiment with business."
    "Maybe this will lessen your grief," said Bob. "Eighty divided by four makes twenty, or at least that's what they always taught us in school. Take these four five-dollar bills, Joe, and dry your tears with them."
    "Oh, boy!" exclaimed Joe.
    "Money, how welcome you are!" ejaculated Herb, as he pocketed his share. "What I can't do with twenty dollars!"
    Every day after that Mr. Robins dropped in in time to hear the market reports, sometimes alone, and at others accompanied by his partner, Mr. Blackford. The latter was not quite so enthusiastic as his colleague, but he was nevertheless greatly interested, and was always glad to don a head set and hear what was going on.
    True to their agreement, the boys instructed the new owner of the set how to adjust it and get the best results. He always paid the closest attention to what they told him, and in a few days could pick up signals and tune the set fairly well.
    "Not bad for an old fellow, eh?" he exclaimed delightedly one day, when he had accomplished the whole thing without any aid from the boys. "If Blackford and I sell out to your father, Bob, I'll have a little leisure time, and blame it all if I don't think I'll do some experimenting and possibly some building myself."
    "You're pretty badly bitten by the radio bug," observed his partner.
    "I won't try to deny it," said the other, emphatically. "The more I think about it, the more wonderful it seems. Besides, it's got a mighty practical side to it. I was holding on to some shares a few days ago until I learned by way of the radio that they were starting to fall. I sent a telegram to my brokers, they sold out for me just in the nick of time, and I made a profit on the deal instead of having to take a loss. The bottom dropped clean out of the market that same afternoon, and if I'd been holding on to those shares, I would have gotten bumped good and hard."
    The other nodded. "It's a good investment when you look at it that way," he admitted.
    "Good investment is right," declared his partner. "I saved a lot more in that deal than the whole radio outfit cost me, and I still own the set."
    "I wonder why the new government wireless station doesn't do something of the kind," remarked Mr. Blackford. "They might as well make themselves useful as well as ornamental."
    "Government station!" exclaimed Bob and Joe at once. "Is there a government station at Mountain Pass?"
    Mr. Blackford nodded. "I thought you fellows knew about it, or I'd have mentioned it before," he said. "It was just opened a few weeks ago, and I don't think they've got all their equipment in yet. There's been some delay in getting the stuff here, I understand."
    "What does the government want of a wireless station away up here?" asked Bob.
    "This is the highest point in all the surrounding country and makes an ideal lookout for forest fires," said his informant. "The station was supposed to be ready for use last summer, but, as I say, was delayed a good deal. But we expect it to be of great service in the future. There have been some disastrous forest fires around here in the last few years, as you probably know."
    "We ought to know it," remarked Joe. "The smoke has been so thick as far away as Clintonia sometimes that you could cut it with a hatchet. It's about time something was done to stop it."
    Of course, once they heard about the government station, the boys could think of nothing else until they had visited it.
    The station was situated some distance from the Mountain Rest Hotel in a clearing cut out of the dense pine woods, and the boys ceased to wonder why they had not discovered it on some of their rambles. As they drew near they could see that everything was solidly and substantially built, as is usually the case with government work.
    The station, besides the towers, comprised a large, comfortable building, which housed all the sending and receiving equipment, and a smaller building, in which the operators slept when off duty, and where spare equipment was stored.
    The radio boys knocked at the door of the larger building, and after a short wait it was opened by a tall, rather frail looking young fellow, who eyed them inquiringly.
    Bob explained that he and his friends were radio fans, and were anxious to look over the station, if it would not cause too much inconvenience.
    "Not a bit of it," said the young operator, heartily. "To tell you the truth, there is not much doing here at this time of year, and company is mighty welcome. Step in and I'll be glad to show you around the place."

CHAPTER  XII

THE  MARVELOUS  SCIENCE

    INSIDE of half an hour the boys were on a friendly footing with the young operator and felt as though they had known him a long time. He was only a few years older than themselves, and had been a full-fledged operator for about six months. The Mountain Pass station was his first assignment, and he was inordinately proud of the complicated apparatus that went to compose it.
    "This is some little station that Uncle Sam has rigged up here, and while there are plenty of bigger ones, there are very few that are more complete and up to date. Look at this three unit generator set, for instance. Compact, neat, and efficient, as you can easily see. It doesn't take up much room, but it can do a whole lot."
    "It does look as though it were built for business," admitted Bob. "I suppose that unit in the center is the driving motor, isn't it?"
    "Right," said the other. "And the one nearest you is a two thousand volt generator for supplying the plate circuit. The one at the other end is a double current generator. That supplies direct current at one hundred and twenty-five volts and four amps for the exciter circuit, and alternating current at eighty-eight volts and ten amps for feeding that twelve volt filament heating transformer that you see over there in the corner."
    "Pretty neat, I'll say," remarked Joe.
    "I think so," said the other, and continued to point out the salient and interesting features of the equipment. "Over here, you see, is our main instrument panel. These dials over here control the variable condensers, and the other ones control the variometers. But there!" he exclaimed, catching himself up short. "I suppose none of you ever heard of such things before, did you?"
    The radio boys looked at each other, and could not help laughing.
    "We've got a faint idea what they are, anyway," chuckled Bob. "We've made enough of them to be on speaking terms, I should say."
    "Made them!" exclaimed the other, surprised in his turn.
    "Sure thing," grinned Bob. "We've made crystal detector sets and vacuum tube sets, and----"
    "And other sets that we never knew just how to describe," interrupted the irrepressible Herb, with a laugh.
    "Yes, that kind too," admitted Bob, with a grin. "But, anyway, we've made enough to know the difference between a variometer and a condenser."
    "Well, I didn't know I was talking to old hands at the game," said the operator. "I suppose I might have known that you wouldn't take that long walk out here through the snow unless you were pretty well interested in radio."
    "Yes, we're dyed-in-the-wool fans," admitted Bob, and told the operator something of their radio work.
    "I'm mighty glad to know that you fellows do understand the subject," said the operator, when Bob had finished. "I'm so enthusiastic about it myself, that it is a real pleasure to have somebody to talk to that knows what I'm talking about. So many of the people who come here seem to be natural born dumb-bells, at least, on the subject of radio."
    "Such as you took us for at first, eh?" asked Jimmy, with a grin.
    "I apologize for that," said the other, frankly. "Please don't hold it against me."
    "Personally, I don't blame you a bit," said Bob. "We can't expect you to be a mind reader."
    "Well, then, that's settled; so let's look at the rest of the station," said the operator, whose name was Bert Thompson. "This is our transmitter panel over here. It is very compact, as you can see for yourselves."
    He opened two doors at the front, one at the bottom, and raised the cover, thus exposing most of the interior mechanism to view.
    "Here are all the fuse blocks down at the bottom, you see," Thompson continued. "The various switches are conveniently arranged where you can easily get at them while you are sitting in front of the panel. Then up here are the microphones, with their coils and wiring where you can easily get at them for inspection or repairs. Rather a neat lay-out, don't you think?"
    "No doubt of it!" exclaimed Bob, admiringly. "We've never made a CW transmitting set yet, but we hope to some day. A set like this would cost a pile of money, even if you made it yourself."
    "Rather so," admitted the young operator. "It takes a rich old fellow like Uncle Sam to pony up for a set like that."
    "We're more interested in receiving sets just at present," said Joe. "Let's take a look at that end of the outfit."
    "Anything you like," said Thompson, readily. "That panel is located on this side of the room."
    "I suppose you use a regenerative circuit, don't you?" asked Bob.
    "Oh, yes," answered the other. "That helps out a lot in increasing the strength of the incoming sounds."
    "I suppose you use a tickler coil in the plate circuit, don't you?" ventured Joe.
    "No, in this set we use a variometer in the plate circuit instead," said Thompson.
    "Speaking of regenerative circuits, have you heard about Armstrong's new invention?" asked Bob.
    The operator shook his head. "Can't say that I have," he said. "It must be something very recent, isn't it?"
    "Yes, I believe it is," said Bob. "I read about it the other day in one of the latest radio magazines."
    "Do you remember how it worked?" asked Thompson, eagerly. "I wish you'd tell me about it, if you do."
    "I'll do my best," promised Bob. "The main idea seems to be to make one tube do as much as three tubes did before. Armstrong found that the limit of amplification had been reached when the negative charge in the tube approaches the positive charge. By experimenting he found that it was possible to increase the negative charge temporarily, for something like one twenty-thousandth of a second, I think it was. This is far above the positive for that tiny fraction of a second, and yet the average negative charge is lower. It is this increase that makes the enormous amplification possible, and lets the operator discard two vacuum tubes."
    "Sounds good," said Thompson. "Do you suppose you could draw me a rough sketch of the circuit?"
    "Let's have a pencil and some paper, and I'll make a try at it," said Bob. "I doped it out at the time, but likely I've forgotten it since then."
    Nevertheless, with the friendly aid of the eraser on the end of the pencil, he sketched a circuit that the experienced professional had no difficulty in understanding.
    "You see," explained Bob, "with this hook up you use the regular Armstrong regenerative circuit, with the second tube connected so that it acts as an automatic switch, cutting in or out a few turns of the secondary coil. The plate circuit of the second tube is connected to the plate of the detector tube through both capacity and inductance."
    "I get you," nodded the operator. "According to your sketch the plate and grid of the second tube are coupled inductively, causing variation in the positive resistance of the tuned circuit."
    "That's the idea exactly," agreed Bob. "You see, this is done by means of the oscillating tube, the grid circuit being connected through the tuned circuit of the amplifying tube."
    "Say, that looks pretty good to me!" exclaimed Thompson. "I wonder how Armstrong ever came to dope that out. I've been trying to get something of the kind for a long time, but I never seemed to get quite the right combination."
    "Well, better luck next time," said Bob, sympathetically. "There are a lot of people working at radio problems, and it seems to be a pretty close race between the inventors. Something new is being discovered almost every day."
    "If you fellows are building sets, you're just as likely to make some important discovery as anybody else," said Thompson. "That super-regenerative circuit is a corker, though. I'm going to keep that sketch you made, if you don't mind, and see if I can make a small set along those line. I have lots of spare time just at present."
    "It will repay you for your trouble, all right," remarked Joe. "We're figuring on doing the same thing when we get back home."
    Jimmy had tried faithfully to follow the technicalities of the recent conversation, but his was an easy going nature, disinclined to delve deeply into the intricate mysteries of science. Herbert was somewhat the same way, and they two wandered about the station, laughing and joking, while Bob and Joe and the young wireless man argued the merits of different equipments and hook-ups.
    "Say!" exclaimed Jimmy, at length, "I hate to break up the party, but don't you think it's about time that we thought of getting back to the hotel? Remember we've got a long way to go, and it's four-thirty already."
    "Gee!" said Bob, glancing in surprise at his watch. "I guess Jimmy is right for once in his life. We'll have to hustle along now, but we'll drop in here often while we are at Mountain Pass--unless you put up a 'no admittance' sign."
    "No danger of that," laughed the other. "The oftener you come, the better I'll like it. This is a lonely place, as you can see for yourselves."
    The radio boys shook hands with Bert Thompson, and after thanking him for the trouble he had taken to show them the station, they started back for the hotel at a brisk pace.
    "Radio is lots of work, but it's also lots of fun," remarked Joe that night, as they sat late reviewing the events of the day.
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    "Radio," repeated Bob. "It's more than fun. It's excitement. It's romance. It's adventure. It's life!"

THE  END