For a long minute the boys and girls stood staring after the strange men dazedly, then they turned to each other with a sigh.

“Well!” said Laura explosively, “if everything isn’t happening to us at once, then my name isn’t Laura Jordon.  To think that our ghost turned out to be an inventor after all!”

“You look as if you were disappointed,” gibed Ferd, beginning to recover from his bewilderment.  “We’ll manufacture a brand new ghost if you say so, but it may take time—­”

“Goodness, you needn’t bother,” said Violet, going over to the wrecked machine and regarding it wonderingly.  “We’ve had enough of ghosts to last us a lifetime.  My, that poor old inventor must have had a terrible fall.”

“It’s a miracle,” said Teddy, who had joined her and was looking down at the wreck soberly, “that he ever came out alive.  I agreed with him at first, that he was all in.”

“Well, let it be a lesson to you,” said Chet with mock gravity, “never to let your ambitions soar to aeroplane inventing.”

“If that’s meant to be a joke,” said Laura bitingly, “I must say it’s as much of a failure as our old inventor himself.  Well, girls,” she added, turning back to them, “I don’t suppose there’s any use staying around here any longer.  Let’s go back to the house.”

It was not till they were entering the grim old door of the grim old house that they thought again of Billie’s new discovery—­the trunk that jingled.

“Goodness! how could we ever have forgotten it?” cried Billie as she, with Violet and Laura, fairly flew up the stairs, leaving the bewildered boys to follow them.

“Now what’s up?” asked Teddy, as he came into the room where the girls had left their treasure.  “So many things are happening all at once that it’s enough to make a fellow’s brain reel.”

“It all depends on the brain,” said Billie, looking up at him with a twinkle in her eye.  And all Teddy did was to look sad and reproachful.

“Say, what shall I be doin’ with this?” asked Mrs. Gilligan, and they turned to see her great bulk looming in the doorway.  In her hand she held the rat trap with the dangling rat.

“Gee, where did you get it?” cried Chet, jumping to his feet from where he had been kneeling with Billie, examining the shabby trunk.

Mrs. Gilligan paused a moment and a gleam of humor shot into her eyes.

“You’ve been askin’ to see ghosts, Mr. Chet,” she said, with a chuckle, “and you sure have got your wish this day.  That airman was the first.  Here is the second one!”

CHAPTER XXIV

COINS AND POSTAGE STAMPS

Chet looked bewildered for a minute—­then disgusted, an expression that was faithfully reflected on the faces of the other boys.

“A ghost!  That?” he said, pointing scornfully at the dead rat.  “What do you mean?”

“Oh, Chet!” cried Billie, springing to her feet in her turn.  “That’s another thing we forgot.  This is Mr. Rat, the piano player.”