“And that will do little good, I fear,” remarked Tom.  “Those fellows have evidently been planning this for some time and will cover their tracks well.  I’d like to catch them, not only to recover your things, dad, but to find out the mystery of my boat and why the man took the tank braces.”

CHAPTER XXI

THE BALLOON ON FIRE

Down Lake Carlopa speeded the arrow, those on board watching the banks slip past as the motor-boat rapidly cut through the water.

“What time do you think we ought to reach home, Tom?” asked Mr. Swift.

“Oh, about four o’clock, if we don’t stop for lunch.”

“Then we’ll not stop,” decided the inventor.  “We’ll eat what we have on board.  I suppose you have some rations?” and he smiled, the first time since hearing the bad news.

“Oh, yes, Ned and I didn’t eat everything on our camping trips,” and Tom was glad to note that the fine weather which followed the storm was having a good effect on his father.

“We certainly had a good time,” remarked Ned.  “I don’t know when I’ve enjoyed a vacation so.”

“It’s too bad it had to be cut short by this robbery,” commented Mr. Swift.

“Oh, well, my time would be up in a few days more,” went on the young bank employee.  “It’s just as well to start back now.”

Tom took the shortest route he knew, keeping in as close to shore as he dared, for now he was as anxious to get home as was his father.  On and on speeded the arrow, yet fast as it was, it seemed slow to Mr. Swift, who, like all nervous persons, always wanted to go wherever he desired to go instantly.

Tom headed his boat around a little point of land, and was urging the engine to the top notch of speed, for now he was on a clear course, with no danger from shoals or hidden rocks, when he saw, darting out from shore, a tiny craft which somehow seemed familiar to him.  He recognized a peculiar put-putter of the motor.

“That’s the Dot,” he remarked in a low voice to Ned, “Miss Nestor’s cousin’s boat.”

“Is she in it now?” asked Ned.

“Yes,” answered Tom quickly.

“You’ve got good eyesight,” remarked Ned dryly, “to tell a girl at that distance.  It looks to me like a boy.”

“No, it’s Mary—­I mean Miss Nestor,” the youth quickly corrected himself, and a close observer would have noticed that he blushed a bit under his coat of tan.

Ned laughed, Tom blushed still more, and Mr. Swift, who was in a stern seat, glanced up quickly.

“It looks as if that boat wanted to hail us,” the inventor remarked.

Tom was thinking the same thing, for, though he had changed his course slightly since sighting the Dot, the little craft was put over so as to meet him.  Wondering what Miss Nestor could want, but being only too willing to have a chat with her, the young inventor shifted his helm.  In a short time the two craft were within hailing distance.