“Yes, and that way you don’t get killed later.”

“It’s the same way with the slide,” the instructor added. “It’s just a kid’s slide, only longer, and you fall harder—that is, if you don’t relax properly.”

After that, for a full week-the two girls practiced swinging, sliding, tumbling, whirling round and round.

“I feel as if I’d been put in a cement mixer and whirled round and round a thousand times,” Sally confided to Danny on Saturday afternoon. “But I do believe that Barbara will go through with it. Monday is our zero hour. We drop at dusk. And I’m keeping my fingers crossed.”

“I’ll say a prayer for you,” Danny grinned. “And now about this secret code of the gremlins, the enemy subs, or what have you.”

“Yes—yes!” Sally exclaimed eagerly. “What did you find out?”

“A whole lot and yet, not half enough. Come over just after chow, if you can. Bring the radios and I’ll tell you all.”

“Oh, no! Surely not that much!” Sally held up her hands in mock horror. “All the same, I’ll be there!”

“It’s like this,” Danny said, as they sat before the radio that night listening to the “put-put-put-a-put.” “They’ve made their code from numbers that can be divided evenly. I’m sure of that. But does one stand for the letter A, or have they arranged it all backwards?”

“They may have started in the middle and gone both ways.”

“Yes, but I don’t think they did. Why should they? They had the wave-length all to themselves. Why not have a simple code? I even think they let one stand for A, three for B, five for C, and so on.”

“What makes you think that?”

“Because eleven, which should stand for E, is used more times than any other number and E is the most-used letter in the alphabet. Other vowels stand out in the same proportion. So I think we’ve got that far. But now,” he sighed, “we’ve got to find out whether they’re sending in German or English. That is going to be hard.”

“And must be continued in our next.” There was a suggestion of gloom in Sally’s voice. She was tired and sore. Much lay ahead.

“Monday we drop from that hole in the sky. Tuesday we take our finals,” she sighed.

“And Wednesday you 

 Prev. P 36/121 next