The days that followed were busy ones. There were shots for typhoid, smallpox and all the rest, with many a sore arm.

They marched until their legs ached and their feet were sore, but all the time their officers were so kind and all their companions so friendly that it did not seem to matter.

Long hours were filled with classes. They learned history of the Navy from the beginning, a glorious story of which they could all be proud. Navy customs came in for their full share of discussion.

“Boy, am I glad I am getting this first!” Sally exclaimed one day. “Without it I’d be completely lost aboard a ship.”

“But we’re not sailing on a ship, at least not the way things stand now,” said Nancy.

“All the same we’re going in for Communications and you can’t communicate with anyone unless you speak his language,” Sally laughed.

“You’ve got something there,” Nancy agreed.

As for Barbara, besides her regular assigned work, she was taken to an airfield where paratroopers were being trained.

As she watched ten boys, one by one, slip from a captive balloon hundreds of feet in the sky, she exclaimed:

“Oh! I could never do that!”

When she saw the parachutes, white against a blue sky, come drifting down and watched the boys drop to the ground as if they were dead, then spring up laughing, she exclaimed:

“That’s wonderful! I’ll do anything, just anything to have a part in that!”

For a time the two black boxes were neglected. Then, one night, they came back with a bang. That was the night following the receipt of a letter from Sally’s old friend, C. K. It ran:

“Dear Sally: Received yours of the 17th. Note what you say about the black boxes.

“Your recent discovery may be of the greatest importance. I refer to the disturbances you think may be messages in code. On that wave-length it can hardly be anything else. Keep it up. You may make a startling discovery. I have definite theory regarding those supposed messages, but will not tell you about it until you have further details.

“You don’t know how to receive in code, do you? It’s not difficult. Get someone there to teach you.

“I agree with you that an outside aerial will help bring out the sounds. But don’t take too many chances just to make an old man’s dream come true.

“Too many chances!” Sally exploded after reading the letter. “There couldn’t possibly be too many chances.”

That very night she started taking the chances.

It was a cloudy, windy night. “Just the night for a murder,” Sally whispered to Nancy as they embarked on their enterprise.

“Or something,” Nancy agreed.

It was Saturday. All the WAVES have Saturday afternoon and night off for shore leave. Most of them would be away so there would be few prying eyes. That was why they had picked on this night for connecting the black boxes with the aerial set up on the roof.

The wires running from Sally’s room up to Nancy’s and to the attic were in place. The lock to the attic door was old. Nancy had solved that with a skeleton key bought at the five and ten.

“There’s no counting of noses at bedcheck tonight,” Sally said. “So we’ll start work at ten. You can be the lookout and I’ll do the work.”

“Don’t forget you’re going to be quite a way up in the air,” Nancy cautioned.

“Oh, I’ve always been a tomboy.” Sally did a cartwheel. “I’ll put on gray slacks and a gray sweater, just in case the moon comes out. The roof is gray, you know.”

“You’d better wear sneakers.”

“Oh, sure!”

And so everything was set for the hour of ten.

“All clear!” Nancy whispered, tiptoeing down the hall. “Deck Three is deserted. Come on up.”

Armed with two pairs of small pliers, a coil of wire, a flashlight and the key to the attic, Sally followed in silence to the floor above. A swift glide, the rattle of a key, the silent opening and shutting of a door and Sally found herself tiptoeing up the attic stairs.

It was a dark and gloomy spot, that attic. As Nancy had put it: “A hundred years look at you up there.”

This was true, for an accumulation of furniture, long outmoded, was stored there. There, too, were all manner of stage drops and settings left over from amateur plays. With her flashlight aimed low, Sally picked her way with care to the nearest gable window.

The window was nailed down but her pliers soon took care of that.

As she stepped out on the roof, clinging to the gable, she took one good look at the world beneath and above her, then shuddered.

With dark clouds rolling through a black, windy sky it was one of those nights that always seemed to depress Sally.

Shaking herself free from her moodiness, she gave close attention to the problem that lay before her.

To discover the end of a wire they had thrust up along the heat pipe and to attach the end of her coil to it was simple enough. From there it was to be a trifle difficult. The roof was not too steep but shingles do not offer much chance for a hand grip. As Nancy had said, it was quite a distance to the ground from there and, though she would not have admitted it for worlds, Sally found herself a little dizzy.

One fact gave her a little comfort. Just beneath the part of the roof where she must do her climbing was an elm tree. Its top was broad and its strong, flexible branches all but brushed the building.

As she stood there hesitating, a group of freshman boys came marching by, singing.

Flattening herself against the gray roof she waited for them to pass. Then, having steeled herself for her task, she thrust her tools into her pockets, held the loose end of the wire in her teeth and began to climb. Clutching with her hands and pushing with her feet, she crept upward. She made slow progress. Now the ridge seemed not so far away. She dared not look back or down.

She was halfway up, when, with startling suddenness, the moon came from behind a cloud.

“Gosh!” she exclaimed, flattening herself against the shingles. She went so flat that she started slowly to slide. After digging in with toes and fingers she managed to hold her ground. And then the moon hid its face.

One more desperate struggle and she found herself sitting triumphantly astride the ridge.

“Now,” she breathed, “all I have to do is to pull the wire tight, attach it to the aerial and then slide down.”

Yes, that was all there was to it, just to slide down.

With fingers that trembled slightly she drew the gray wire tight against the roof, cut it at the right place and then, with the skill of a lineman, wound it tight, round and round the original wire leading to the aerial.

She had twisted herself back to a place astride the roof when again the moon showed its face.

At the same instant she thought she heard someone far below let out a low whistle. She couldn’t let herself be seen sitting there, just couldn’t. That might mean catastrophe.

Then it happened. In attempting to throw herself flat, she overdid the matter. Missing a grip on the ridge, she heard her flashlight go rolling down the roof. And, in quite an involuntary manner, she came gliding, clawing and kicking after it.

Recalling the tree and at the same time realizing that she was powerless to check her slow glide, she managed somehow to swing half about. When she left the roof, she rolled off, felt the brush of a leafy branch, struck out desperately with her hands, gripped a branch, clung there and found herself at last dangling in mid-air. Or was she two-thirds of the way down? There was no way of knowing.

Clinging desperately to the cracking branch, she dared not call for help. What was to be done? Feeling a larger branch against her back, she tried to turn about. She had made half the swing just as her slender branch gave an ominous crack.

At the same time a voice from below said: “Come on down, sister. I’ll catch you.”

“Good grief!” she thought. “It’s a man.” And then the branch broke.

She landed rather solidly in a pair of strong arms. Then her feet hit the ground. Also the moon came out.

“What were you doing up there?” The man held her, as if she were a sack of wheat that might fall over.

The moonlight was on his face. He was young and wore a heavy blue coat. His cap had been knocked off.

“That,” she replied slowly, “is a military secret. But the way I came down, it seems, is common knowledge.” She did not try to escape.

“Rather uncommon knowledge, I’d say,” he drawled. “You might have broken your neck.”

“Yes, or been caught.”

“You were that,” he chuckled. “And you’re not a bad catch, at that. This is a rather lonesome college for some folks. Tell me who you are and I’ll let you go.

“I will anyway,” he said dropping his hands.

“I’m Sally Scott and I’m a WAVE!” she confessed.

“A WAVE! Then we belong to the same outfit. I’m a flying sailor. Shake!” He put out a hand for a good handclasp.

“Oh! A flying sailor!” she exclaimed. “Then you could teach me to receive in code.”

“Certainly I could and will, in my spare time.”

“We have an hour after supper.”

“Suits me. But, say, now that I have you, how about a coke and a chat somewhere?”

She did not reply at once. “We—we have to be careful. Mind taking my pal along?”

“Not a bit.”

“Then it’s a go. I—Oh, boy! Nancy will think I’m dead, or something! Wait. I’ll be back.”

“I’ll wait.”

She was gone.

“Sally Scott! How did you get down that way?” Nancy exclaimed as Sally came racing up the second story ladder, instead of coming down from the attic.

“I—I found a new way to get down and, and I found a nice new boy,” Sally panted. “He wants to buy us a coke. Come on, let’s go.”

“Sally, you didn’t,” Nancy protested. “Besides, there’s a scratch on your face. It’s bleeding.”

“All right then, I didn’t.” Sally dabbed at her cheek. “You won’t believe me if I tell you the truth.”

“Try me.”

“All right then, after I got the wire all fixed. I fell off the roof, landed in a tree and hung to a branch as long as I could and what do you think?”

“A nice boy caught you. And you expect me to believe that?”

“All right, then don’t. Anyway the wire is up.”

“And now we can get London, Paris, and Berlin. Come on. Let’s try.”

“No,” Sally seized Nancy’s arm. “The nice boy is real. Come on, let’s go.”

“You wouldn’t go looking like that?”

“I’ll wash the blood off my face. We’ve got to get in uniform. Must wear them even off duty, you know!”

So Sally was off to the washroom to bathe her cheek.

“Now I ask you,” Nancy challenged the empty air, “how can they hope to make a WAVE out of a girl like that?”

Sally was back in a minute and slipped into her uniform. Nancy was ready a moment later and then they were down the stairs and out into the night.

“This is Nancy McBride.” Sally introduced her companion to the flying sailor who had stepped out into the moonlight.

“I’m pleased to meet you, Nancy. I’m Danny Duke,” he said. “Distant relative of the famous Dukes, so distant that they never even sent me a package of Duke’s mixture. Do you also walk in your sleep? And may I be looking for you on the roof tops?”

“Sally wasn’t walking in her sleep,” said Nancy, “but tell me, did she really fall off the roof and did you catch her?”

“Shall I tell her?” Danny turned to Sally.

“Sure. Tell her. She wouldn’t believe me.”

“Well, then,” said Danny, in a mock-solemn voice, “it’s really true. I made a real catch that time. But then, the elm helped out a lot.”

“Good old elm!” Sally exclaimed. “I’ll never forget it! And now,” she added, “I feel in need of reviving.”

The reviving came with good steaming cups of coffee.

Danny Duke could stand the glare of a neon light, Sally found as she looked at his strong, friendly face.

“I’m just past twenty,” he told them with a touch of boyish pride. “And my training is about finished right now.”

“How is it you’re here so far from the Navy flying schools?” Nancy asked.

“I was back on some math, so they sent me here to brush up. I’ve about got it now. Another two weeks will do it.”

“Too bad,” Sally sighed. “But that will be time enough to teach me to receive code, won’t it?”

“Oh, sure,” Danny grinned. “But say, are you the practical young miss! Here I save your life, and first thing you insist that I do something more for you.”

“It’s not for me.” Leaning across the table Sally allowed her voice to drop. “It’s much more important than that, I hope. It’s for our old friend Uncle Sam. The things I did up there on the roof are part of it, just as my learning code will be. You are such a nice boy, I want you to have a part in it.”

“Well, thanks—” Danny was visibly embarrassed. “Thanks a lot: I’ll help all I can.”

The truth is that Danny was to have a much greater part in the undertaking than either he or Sally knew.

“And now for one more try at the two black boxes,” Sally whispered excitedly after the girls had said good-bye at the gangplank of their ship that really wasn’t a ship at all.

“It works! And it’s going to help a lot, that aerial is,” Sally exclaimed a few minutes later.

This was true. They were able now to catch the “put-put-put-put” of those secret broadcasts sent from radios out somewhere on land or sea very plainly. That night they stayed up till midnight, and were able to locate seven different broadcasters.

“They are all part of something big, I know that,” Sally insisted. “But is it a sub pack, a flight of planes, or a convoy of ships?”

“Only time will tell,” was Nancy’s reply.

Just then they caught the sound of voices in the hall and suddenly their secret listenings to the great unknown were at an end. For if the secret radio were to remain just that, they must take great care not to expose either the black box or the purpose of their own midnight meetings. The two conspirators did not intend to be found out.