me? Bless my soul and gizzard!"

"Mr. Damon!" exclaimed Tom, shutting off the power, for he was now near shore. "Of course I'll help you, Mr. Damon," for the young inventor had recognized the eccentric man of whom he had purchased the motor-cycle and who had helped him in rounding up the thieves.

"Why, bless my shoe-laces, if it isn't Tom Swift!" exclaimed Mr. Damon, who seemed very fond of calling down blessings upon himself or upon articles of his dress or person.

"Yes! I'm here," admitted Tom with a laugh.

"And in a motor-boat, too! Bless my pocketbook, but did that run away with some one who sold it to you cheap?"

"No, not exactly," and the lad explained how he had come into possession of it. By this time he was ashore and had tied the ARROW to an overhanging tree. Then Tom proceeded to where Mr. Damon had left his stalled automobile. The eccentric man was wealthy and his physician had instructed him to ride about in the car for his health. Tom soon located the trouble. The carburetor had become clogged, and it was soon in working order again.

"Well, now that you have a boat, I don't suppose you will be riding about the country so much," commented Mr. Damon as he got into his car. "Bless my spark-plug! But if you ever get over to Waterfield, where I live, come and see me. It's handy to get to by water."

"I'll come some day," promised the lad.

"Bless my hat band, but I hope so," went on the eccentric individual as he prepared to start his car.

Tom completed the remainder of the trip to his house without incident and his father came down to the dock to see the motor-boat. He agreed with his son that it was a bargain and that it could easily be put in fine shape.

The youth spent all the next day and part of the following working on the craft. He overhauled the ignition system, which was the jump-spark style, cleaned the magneto and adjusted the gasoline and compression taps so that they fitted better. Then he readjusted the rudder lines, tightening them on the steering wheel, and looked over the piping from the gasoline tank.

The tank was in the forward compartment, and, upon inspecting this, the lad concluded to change the plan by which the big galvanized iron box was held in place. He took out the old wooden braces and set them closer together, putting in a few new ones.

"The tank will not vibrate so when I'm going at full speed," he explained to his father.

"Is that where the strange man was tampering with the lock the day of the auction?" asked Mr. Swift.

"Yes, but I don't see what he could want in this compartment, do you dad?"

The inventor got into the boat and looked carefully into the rather dark space where the tank fitted. He went over every inch of it, and, pointing to one of the thick wooden blocks that supported the tank, asked:

"Did you bore that hole in there, Tom?"

"No, it was there before I touched the braces. But it isn't a hole, or rather, someone bored it and stopped it up again. It doesn't weaken the brace any."

"No, I suppose not. I was just wondering whether that was one of the new blocks or an old one."

"Oh, an old one. I'm going to paint them, too, so in case the water leaks in or the gasoline leaks out the wood won't be affected. A gasoline tank should vibrate as little as possible, if you don't want it to leak. I guess I'll paint the whole interior of this compartment white, then I can see away into the far corners of it."

"I think that's a good idea," commented Mr. Swift.

It was four days after his purchase of the boat before Tom was ready to make a long trip in it. Up to that time he had gone on short spins not far from the dock, in order to test the engine adjustment. The lad found it was working very well, but he decided with a new kind of spark plugs for the two cylinders that he could get more speed out of it. Finally the forward compartment was painted and a general overhauling given the hull and Tom was ready to put his boat to a good test.

"Come on, Ned," he said to his chum early one evening after Mr. Swift had said he was too tired to go out on a trial run. "We'll see what the ARROW will do now."

From the time Tom started up the motor it was evident that the boat was going through the water at a rapid rate. For a mile or more the two lads speeded along, enjoying it hugely. Then Ned exclaimed:

"Something's coming behind us."

Tom turned his head and looked. Then he called out:

"It's Mr. Hastings in his new CARLOPA. I wonder if he wants a race?"

"Guess he'd have it all his own way," suggested Ned.

"Oh, I don't know. I can get a little more speed out of my boat."

Tom waited until the former owner of the ARROW was up to him.

"Want a race?" asked Mr. Hastings good-naturedly.

"Sure!" agreed Tom, and he shoved the timer ahead to produce quicker explosions.

The ARROW seemed to leap forward and for a moment was ahead of the CARLOPA, but with a motion of his hand to the spark lever Mr. Hastings also increased his speed. For a moment the two boats were on even terms and then the larger and newer one forged ahead. Tom had expected it, but he was a little disappointed.

"That's doing first rate," complimented Mr. Hastings as he passed them. "Better than I was ever able to make her do even when she was new, Tom."

This made the present owner of the ARROW feel somewhat consoled. He and Ned ran on for a few miles, the CARLOPA in the meanwhile disappearing from view around a bend. Then Tom and his chum turned around and made for the Swift dock.

"She certainly is a dandy!" declared Ned. "I wish I had one like it."

"Oh, I intend that you shall have plenty of rides in this," went on his friend. "When you get your vacation, you and dad and I are going on a tour," and he explained his plan, which, it is needless to say, met with Ned's hearty approval.

Just before going to bed, some hours later, Tom decided to go down to the dock to make sure he had shut off the gasoline cock leading from the tank of his boat to the motor. It was a calm, early summer night, with a new moon giving a little light, and the lad went down to the lake in his slippers. As he neared the boathouse he heard a noise.

"Water rat," he murmured, "or maybe muskrats. I must set some traps."

As Tom entered the boathouse he started back in alarm, for a bright light flashed up, almost in his eyes.

"Who's here?" he cried, and at that moment someone sprang out of his motor-boat, scrambled into a rowing craft which the youth could dimly make out in front of the dock and began to pull away quickly.

"Hold on there!" cried the young inventor. "Who are you? What do you want? Come back here!"

The person in the 'coat returned no answer. With his heart doing beats over-time Tom lighted a lantern and made a hasty examination of the ARROW. It did not appear to have been harmed, but a glance showed that the door of the gasoline compartment had been unlocked and was open. Tom jumped down into his craft.

"Some one has been at that compartment again!" he murmured. "I wonder if it was the same man who acted so suspiciously at the auction? What can his object be, anyhow?"

The next moment he uttered an exclamation of startled surprise and picked up something from the bottom of the boat. It was a bunch of keys, with a tag attached, bearing the owner's name.

"Andy Foger!" murmured Tom. "So this is, how he was trying to get even! Maybe he started to put a hole in the tank or in my boat."