He passed Andy Foger, who had worked his way over near him.

"You got the boat," sneered the bully, "and I s'pose you think you got ahead of me."

"Keep quiet!" begged Sam.

"I won't!" exclaimed Andy. "He outbid me just out of spite, and I'll get even with him. You see if I don't!"

Tom looked Andy Foger straight in the eyes, but did not answer, and the red-haired youth turned aside, followed by his crony, and started toward his automobile.

"I congratulate you on your bargain," said Mr. Wood as Tom proceeded to make out a check. He gave little thought to the threat Andy Foger had made, but the time was coming when he was to remember it well.

CHAPTER III

A TIMELY WARNING

"Well, are you satisfied with your bargain, Tom?" asked Mr. Wood when the formalities about transferring the ownership of the motor-boat had been completed.

"Oh, yes, I calculated to pay just what I did."

"I'm glad you're satisfied, for Mr. Hastings told me to be sure the purchaser was satisfied. Here he comes now. I guess he wasn't at the auction."

An elderly gentleman was approaching Mr. Wood and Tom. Most of the throng was dispersing, but the young inventor noticed that Andy Foger and Sam Snedecker stood to one side, regarding him closely.

"So you got my boat," remarked the former owner of the craft. "I hope you will be able to fix it up."

"Oh, I think I shall," answered the new owner of the CARLOPA. "If I can't, father will help me."

"Yes, you have an advantage there. Are you going to keep the same name?" and Mr. Hastings seemed quite interested in what answer the lad would make.

"I think not," replied Tom. "It's a good name, but I want something that tells more what a fast boat it is, for I'm going to make some changes that will increase the speed."

"That's a good idea. Call it the Swift."

"Folks would say I was stuck up if I did that," retorted the youth quickly. "I think I shall call it the ARROW. That's a good, short name, and—"

"It's certainly speedy," interrupted Mr. Hastings. "Well now, since you're not going to use the name CARLOPA, would you mind if I took it for my new boat? I have a fancy for it."

"Not in the least," said Tom. "Don't you want the letters from each side of the bow to put on your new craft?"

"It's very kind of you to offer them, and, since you will have no need for them, I'll be glad to take them off."

"Come down to my boat," invited Tom, using the word "my" with a proper pride, "and I'll take off the brass letters. I have a screw driver in my motor-cycle tool bag."

As the former and present owners of the ARROW (which is the name by which I shall hereafter designate Tom's motor-boat) walked down toward the dock where it was moored the young inventor gave a startled cry.

"What's the matter?" asked Mr. Hastings.

"That man! See him at my motor-boat?" cried Tom. He pointed to the craft in the lake. A man was in the cockpit and seemed to be doing something to the forward bulkhead, which closed off the compartment holding the gasoline tank.

"Who is he?" asked Mr. Hastings, while Tom started on a run toward the boat.

"I don't know. Some man who bid on the boat at the auction, but who didn't go high enough," answered the lad. As he neared the craft the man sprang out, ran along the lakeshore for a short distance and then disappeared amid the bushes which bordered the estate of Mr. Hastings. Tom hurriedly entered the ARROW.

"Did he do any damage?" asked Mr. Hastings.

"I guess he didn't have time," responded Tom. "But he was tampering with the lock on the door of the forward compartment. What's in there?"

"Nothing but the gasoline tank. I keep the bulkhead sliding door locked on general principles. I can't imagine what the fellow would want to open it for. There's nothing of value in there. Perhaps he isn't right in his head. Was he a tramp?"

"No, he was well dressed but he seemed very nervous during the auction, as if he was disappointed not to have secured the boat. Yet what could he want in that compartment? Have you the key to the lock, Mr. Hastings?"

"Yes, it belongs to you now, Mr. Swift," and the former owner handed it to Tom, who quickly unlocked the compartment. He slid back the door and peered within, but all he saw was the big galvanized tank.

"Nothing in there he could want," commented the former owner of the craft.

"No," agreed Tom in a low voice. "I don't see what he wanted to open the door for." But the time was to come, and not far off, when Tom was to discover quite a mystery connected with the forward compartment of his boat, and the solution of it was fated to bring him into no little danger.

"It certainly is odd," went on Mr. Hastings when, after Tom had secured the screw driver from his motor-cycle tool bag, he aided the lad in removing the letters from the bow of the boat "Are you sure you don't know the man?"

"No, I never saw him before. At first I thought his voice sounded like one of the members of the Happy Harry gang, but when I looked squarely at him I could not see a bit of resemblance. Besides, that gang would not venture again into this neighborhood."

"No, I imagine not. Perhaps he was only a curious, meddlesome person. I have frequently been bothered by such individuals. They want to see all the working parts of an automobile or motor-boat, and they don't care what damage they do by investigating."

Tom did not reply, but he was pretty certain that the man in question had more of an object than mere curiosity in tampering with the boat. However, he could discover no solution just then, and he proceeded with the work of taking off the letters.

"What are you going to do with your boat, now that you have it?" asked Mr. Hastings. "Can you run it down to your dock in the condition in which it is now?"

"No, I shall have to go back home, get some tools and fix up the motor. It will take half a day, at least. I will come back this afternoon and, have the boat at my house by night. That is if I may leave it at your dock here."

"Certainly, as long as you like."

The young inventor had many things to think about as he rode toward home, and though he was somewhat puzzled over the actions of the stranger, he forgot about that in anticipating the pleasure he would have when the motor-boat was in running order.

"I'll take dad off on a cruise about the lake," he decided. "He needs a rest, for he's been working hard and worrying over the theft of the turbine motor model. I'll take Ned Newton for some rides, too, and he can bring his camera along and get a lot of pictures. Oh, I'll have some jolly sport this summer!"

Tom was riding swiftly along a quiet country road and was approaching a steep hill, which he could not see until he was close to it, owing to a sharp turn.

As he was about to swing around it and coast swiftly down the steep declivity he was startled by hearing a voice calling to him from the bushes at the side of the road.

"Hold on, dar! hold on, Mistah Swift!" cried a colored man, suddenly popping into view. "Doan't go down dat hill."

"Why, it's Eradicate Sampson!" exclaimed Tom, quickly shutting off the power and applying the brakes. "What's the matter, Rad? Why shouldn't I go down that hill?"

"Beca'se, Mistah Swift, dere's a pow'ful monstrous tree trunk right across de road at a place whar yo' cain't see it till yo' gits right on top ob it. Ef yo' done hit dat ar tree on yo' lickity-split machine, yo' suah would land in kingdom come. Doan't go down dat hill!"

Tom leaped off his machine and approached the colored man. Eradicate Sampson did odd jobs in the neighborhood of Shopton, and more than once Tom had done him favors in repairing his lawn mower or his wood-sawing machine. In turn Eradicate had given Tom a valuable clue as to the hiding place of the model thieves.

"How'd the log get