“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.