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 lines. 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.

The days were growing very short, and it was after dark when they reached the hotel. Very warm and comfortable it looked as they approached it, windows lighted and throwing cheerful beams over the white snow outside. A red glow filled the windows of the living room, and the boys knew that a big wood fire was roaring and crackling in the big fireplace. As they drew close, a tempting aroma of cookery reached them, and caused them to hasten their steps.

They had barely time to get freshened up before the dinner bell rang, and in a short time they were making havoc with as fine a meal as any of them ever tasted.

When they told about their visit to the radio station, Edna and Ruth Salper, the daughters of the Wall Street broker they had met in the snowstorm, were among the most interested of the listeners.

"We find it so dull over at our house we are glad to come over here for meals and to visit," said Ruth Salper.

"I suppose being in the woods in winter is rather dull," returned Joe, politely.

"Did you boys really know enough about radio to talk all afternoon with the man in charge of the government station?" inquired Edna, curiously.

"Why not?" asked Bob. "Don't you think radio is a broad enough subject to talk about for an entire afternoon?"

"Oh, I suppose it is," she admitted. "But why don't you share some of your fun with us?"