ed Tom, as he brought
the craft to a stop in front of the hangar, and Jackson and his
helpers, who were awaiting the return, hurried out to take charge.

"Yes, everything seems to point to success, Tom," agreed Mr. Damon.
"That is, unless the slight accident we had means trouble."

"Oh, no, that had nothing to do with the operation of the silencer. But
I'm going to do better yet. Some day I'll take you for a ride in a
silent machine which will make so little noise that you can hear a pin
drop."

"Well," remarked Mr. Damon' with a laugh, "I don't know that listening
to falling pins will give me any great amount of pleasure, Tom, but I
appreciate your meaning."

"Everything all right?" asked Mr. Swift, as he came out to hear the
details from his son. "Do you think you have solved the problem?"

"Not completely, but I'll soon be able to write Q. E. D. after it. Some
refinements are all that are needed, Dad."

"Glad to hear it. I was a bit anxious."

Mr. Swift questioned his son about the technical details of the trip,
asking how the motor had acted under the pressure caused by so
completely muffling the exhaust, and for some minutes the two
inventors, young and old, indulged in talk which was not at all
interesting to Mr. Damon. They went into the house, and Tom asked to
have a little lunch, which Mrs. Baggert set out for him.

"It's rather late to eat," said the young inventor, "but I always feel
hungry after I test a new machine and find that it works pretty well.
Will you join me in a sandwich or two, Mr. Damon?"

"Why, bless my ketchup bottle, I believe I will."

And so they ate and talked. Tom was on the point of telling his father
something of the queer cry for help they had heard on the lonely meadow
when Mrs. Baggert produced a letter which she said had come for Tom
that afternoon, but had been mislaid by a new maid who had been engaged
to help with the housework.

"She took it to the shop after you had left, and only now told me about
it," explained Mrs. Baggert. "So I sent Eradicate for it."

"How long ago was that?" asked Tom, as he took the missive.

"Oh, an hour ago," answered Mrs. Baggert, with a smile. "But don't
blame poor Rad for that. He wanted to deliver the letter to you
personally, and so did Koku. The result was your giant kept after Rad,
trying to get the letter from him, and Rad kept hiding and slinking
about for a chance to see you himself until I saw what was going on, a
little whi