There was a glorious hour at sunset in every day of work when Sally was free to do as she chose. What she chose more often than not, in the days that followed, was to visit a certain radio lab in one of the school’s regular buildings. Here she found Danny waiting to help her with her problems. She discovered at once that he did know a very great deal about communication and about radio in particular.

When she complimented him on his knowledge he threw back his head and laughed.

“It’s no fault of mine,” he exclaimed. “I’ve had it drilled into me from the very start. We’re in the Navy. Don’t forget that. Most of us will be on aircraft carriers. That means we’ll be out over the sea in small planes.”

“Alone?” Sally asked.

“Sometimes, sometimes not. You may have a radioman and may not. Anyway, he may get killed. So you have to know all about radio, blinking lights, waving flags, and a lot more.

“Say!” he laughed. “I could propose to a good signal girl in ten different ways.”

“Wait till I get up on all the codes,” Sally laughed.

“Oh, yes. Well, then, let’s get busy.”

He picked up a booklet entitled, “International Code” and; turning to page twelve, said:

“Morse code isn’t half bad. See! Here it is.” Sally looked over his shoulder. “A is dot, dash; B is dash, dot, dot dot, and so on down the line. You can learn all that in about no time. But receiving takes longer. Those birds send out messages like greased lightning. You’ve got to think fast and be accurate at the same time. That’s tough. But it’s absolutely necessary, especially in your work. To read a message wrong, skip a dot here and miss a dash there, may sink a ship, or even a half dozen ships.”

“Oh!” Sally held her head. “That sounds serious!”

“It is. But see here, why do we waste a beautiful sunset hour on code? You’ll get that in your next school anyway.”

“Yes, I know, but I want it now. It,” she hesitated, “it’s not my secret alone so I can’t tell you too much.”

“You don’t have to tell me anything,” he replied with a generous smile.

“But I want to. That night when I fell off the roof I was running a wire from my room to the aerial on the roof. I’ve been working for a long time with a dear old man who’s a real genius. He invented a special kind of radio and he gave me two of them to try out.”

“I see. That’s what you’re doing now. Did the outside aerial help?”

“Oh, yes, a whole lot. The ‘put-puts’ come in a whole lot more distinctly.”

“The what?” He stared.

“The ‘put-puts’. That’s what we call them. I suppose it’s some special form of code, but it’s not like any I’ve ever heard on the short wave section of our radio.”

“I wish you’d tried to write it down,” he said thoughtfully. “Perhaps they have a secret code. They may substitute numbers for letters. See, here are the numbers in Morse Code. Dot, dash, dash, dot are for one, for two you add two dots and drop a dash-dot, dot, dash, dot. Three is dot, dot; dot, dash, dot, and so on.”

“That doesn’t sound too hard,” interrupted Sally.

“It’s simple. Take this book home and learn the numbers. Then listen to your radio and try to write down the ‘put-puts’ in dots and dashes.”

“I will if they are there tonight. Sometimes they’re not there at all and sometimes there are a lot of them, five, six, or a dozen, all talking to one another like frogs in a pond.”

“Is that right!” He suddenly became excited. “Say, perhaps they are in a pond, the big pond. Perhaps they are wolves instead of frogs.”

“Wolves?”

“Sure, enemy subs, wolf-packs of them, you know. Wouldn’t that be a break?”

“I—yes, I suppose so.”

“You suppose so! Say! You don’t know the half of it! These wolf-packs are known to have some means of talking to one another under the water.”

“They’d almost have to.”

“Sure they would, but all the bright minds in Europe and America can’t find out how they do it.

“But then,” his voice dropped, “probably your ‘put-puts’ come from a flight of planes crossing to North Africa.”

“Or from a convoy.”

“Sure. We, too, have our secret methods of communication, but if your old friend has invented a new one, they’ll make him an admiral.”

“It’s up to me to prove it. That’s why I’m so anxious about it.”

“It is? Well, then, we’ll really dig in. Try out my code idea. Then we’ll meet again at sunset tomorrow.”

“It’s a date.” She left the lab with a smile. Even if nothing came of this code idea she had made a grand friend and that was always worth while.

Late that evening while others wrote letters, read or slept, Sally gave herself over once more to solving the riddle of the secret radio and its “put-puts.” She had made very little progress when the signal sounded for lights out.

“Oh, dear!” she sighed. “No day is ever long enough.”

She had been in bed for a half hour but had not fallen asleep when suddenly she caught a gleam of light from Barbara’s bed.

“Barbara!” she exclaimed. “What are you doing?”

The light blinked out and Barbara’s head came out from beneath the covers.

“I’m sorry!” Barbara whispered back. “These studies are so hard and there are so many of them I never get caught up. So I’ve been studying with a flashlight under the covers. No one would know it but you.”

“Such determination!” Sally exclaimed in a low voice. “You should have a medal or something. But you’ll smother!”

“Oh, no!” Barbara laughed. “I’m like a seal. I come up for air.”

“Anyway it’s an idea,” said Sally. Hopping out of bed, she gathered in her precious radio and, with a bed cover for a tent, studied the “put-puts” for another hour.

The close of that hour found her thoroughly disgusted. On a paper she had made a few marks. When she had compared these to the code marks for letters and figures, they added up to exactly nothing.

“Terrible,” she thought. “I know what I’ll do. I’ll take the radio over to the lab and show it to Danny. I’m sure he can be trusted. We’ll work things out together.”

“What’s that black box?” Danny asked, when she arrived next evening.

“That’s my secret radio. I couldn’t do a thing last night. I want you to help me.”

“It’s nice of you to trust me.” He beamed. “People have said I was simple but could be trusted. Only time will tell.”

“Time doesn’t need to tell me. I know it.”

“Do you? Well, then that’s fine. How do you open this black box?”

She snapped it open. “Oh! We need an aerial!”

“There’s one on this building, much better than the one you’ve been using. There’s a connection over in the corner.”

In a few minutes the radio was ready to operate. Sally turned the switches. Nothing came out, not a sound.

“What’s up?” Danny asked.

“Those gremlins, subs, or whatever they are, are not always there.”

“Turn the dial. Get something else. That will tell us whether our connections are okay.”

“There’s nothing else on the air for us.”

“That’s a queer radio.”

“Yes, it is. But if we wait five minutes Station NANCY will be on the air.”

“And in the meantime?”

“Tell me about parachutes,” she begged. “You’ve dropped a time or two, haven’t you?”

“Naturally. I’m a flier.”

“How does it feel to drop for the first time?”

“Just fine if you think of something else most, of the time. It helps to sing:

“But why all the interest in parachutes?”

“My roommate is going to be a parachute rigger.”

“I hope she’s a careful sort of lady. I saw a boy drop two thousand feet straight down. His rigger had failed him.”

“I’ll rig my own.” Sally’s lips were a straight line.

“Why should you go in for parachutes? But then—oh, yes—you go in for all sorts of falling.” He laughed.

“No,” she said, “I don’t. I get dizzy. But I promised Barbara that I’d go down with her it they asked her to try parachuting.”

“You did! That takes courage!”

“Where’s the war job that doesn’t?”

“Oh, it’s not so bad.” He blew an imaginary smoke ring. “You just sit on the edge of a hole until they give you the word. Then you look up, slide through the hole, and down you go. When the parachute is open it is really swell, like dreams we have of flying just with our hands. When you land you curl up like a sleepy kitten, roll on the ground, then get up.”

“You make it sound so nice!”

“Why not?”

Sally turned a knob on the radio. She snapped on a headset and said: “Hello, are you there?” Then she listened.

“How do you get me?” she spoke into the mouthpiece again. “Good as ever? That’s fine. This is Sally signing off.

“See!” She turned to Danny.

“Pete’s sake! What wave-length do you use?”

“I don’t know.”

“What?”

“Only one person in the world knows that. He’s the man who made it. My old friend C. K. All I know is, it’s very short. Watch!”

She snapped off the lights, then pulled down the shades. The radio’s tubes glowed red.

“Say! A radio with its own private wave length is worth a fortune! I know a man high up in Communications. Let me show it to him.”

“Not for worlds.”

“You’ll be rich and famous.”

“No! No! Oh, I wish I hadn’t brought it here. Can’t you see that it was loaned to me by a very dear friend and that he alone can release it?”

“Yes,” he replied soberly. “I won’t breathe a word about it until you give me the sign.”

“Thanks—oh, thanks!” she stammered. “You really had me worried.”

“And now,” he said, “how about having another try at the ‘put-put’ of the gremlins, or subs?”

For ten minutes more they sat there in the dark watching the red glow of the strange radio tubes but hearing just nothing at all.

Then, suddenly, it came, a low “put-put-put-put-a-put-put-put-put-a-put.”

For a long time Danny sat there silently listening. “It’s code, all right,” he murmured once. “There’s a sort of rhythm to it, just as there is to all code.”

“If you turn this dial,” Sally whispered, “it will throw them out.” She turned the dial. Silence followed, but not for long. Again came “put-put-put-a-put.”

“They’re back,” he whispered.

“No, that’s another one. Listen! You can tell the difference.” She brought the first one back, then switched to the second.

“What do you know about that!” He was all ears.

“Perhaps the ‘put’ stands for dot, and ‘put-a-put’ for dash,” he suggested. “I’ll just try it that way.”

“Might be the opposite!”

“Sure, just anything.” He snapped on a small light and then began marking down dots and dashes as he listened. For a long time neither of them spoke.

“That might be it,” he breathed at last. “It’s hard to take down, but I’ve got dot, dot, dot, dash, dot. That’s three, dash, dash, dash for five and dash, dash, dot, dot, for seven. Then there are some numbers that seem like seventeen, twenty-three, and thirty-one. I can’t be sure—”

“Give me a pencil and paper,” she suggested. “Let me play the game.”

For a long time after that they listened and marked down dots and dashes. When one sender went off the air they switched to another. In time they came to believe that number one and number two were holding a conversation. Then number two went off the air, followed by number one.

A little search found a third. When number three went dead, number one was at it again. It became an interesting game of hide-and-go-seek, in the air.

“Could it be one of our convoys?” Sally asked.

“Hardly that. They maintain radio silence, I’m told. But with such a radio, who knows? But if they are subs, a whole wolf-pack of them!” he exclaimed a moment later.

“And if we could spot them!”

“While we were on a ship, an aircraft carrier! Spot them some distance away and go after them with a dozen planes loaded with depth-bombs. I’ll tell you what!” he exclaimed, becoming greatly excited. “I’ll be ready to sail in a month or two, on an aircraft carrier. You get a radio job on my ship. Then we’ll really try this radio out.”

“They’re not sending WAVES on ships yet,” she reminded.

“Oh! We’ll manage it,” he insisted, “We’ll just have to.”

“We may discover that we’re mostly just duplicating one of Uncle Sam’s secrets.” Sally was cautious by nature. “These code signals may come from American ships or airplanes.”

“Tell you what!” he exclaimed. “We’ve just got to de-code their messages so we can tell what they say. Then we’ll know. But that,” he sighed heavily, “looks like a long, long job.”

They pitched into that job once more and had been working for some time when he said: “By the way, did you have a class tonight?”

“Yes, from eight to nine.”

“Never mind then, it’s nine now.”

“Oh!” she exclaimed. “I must go! I’ll get a black mark. Unhook my radio and let me go.”

“There you are,” he said a moment later, as he handed her the radio, “but you’ll be back?”

“Oh! Sure! It’s been exciting. Just think what it will mean if we really do something big with old C. K.’s radio.”

“I have been thinking,” he replied soberly. “Just keep trying, and mum’s the word. We’ll get there yet!”