Glancing with critical eyes at the craft of his rival, Tom saw that Andy Foger had a very fine boat. The young inventor also realized that if he was to come anywhere near winning the race he would have to get the utmost speed out of his engine, for the new boat the bully had was designed primarily, for racing, while Tom's was an all-around pleasure craft, though capable of something in the speed line.

"I'll be giving you a tow in a few minutes, as soon as my engine gets warmed up!" sneered Andy.

"Maybe," said Tom, and then he crouched down to make as little resistance as possible to the wind. Andy, on the contrary, sat boldly upright at the auto steering wheel of his boat.

On rushed the two motor craft, their prows exactly even and the propellers tossing up a bulge in the water at their sterns. Rapidly acquiring speed after the two lads had adjusted the timers on their motors, the boats were racing side by side, seemingly on even terms.

The Red Streak had a very sharp prow, designed to cut through the water. It was of the type known as an automobile launch. That is, the engine was located forward, under a sort of hood, which had two hinged covers like a bat's wings. The steering-wheel shaft went through the forward bulkhead, slantingly, like the wheel of an auto, and was arranged with gasoline and sparking levers on the center post in a similar manner. At the right of the wheel was a reversing lever, by which the propeller blades could be set at neutral, or arranged so as to drive the boat backward. Altogether the Red Streak was a very fine boat and had cost considerably more than had Tom's, even when the latter was new. All these things the young owner of the Arrow thought of as he steered his craft over the course.

"I hardly think I can win," Tom remarked to himself in a whisper. "His boat is too speedy for this one. I have a chance, though, for his engine is new, and I don't believe he understands it as well as I do mine. Then, too, I am sure I have a better ignition system."

But if Tom had any immediate hopes of defeating Andy, they were doomed to disappointment, for about two minutes after the race started the Red Streak forged slowly ahead.

"Come on!" cried the red-haired lad. "I thought you wanted a race."

"I do," answered the young inventor. "We're a long way from the dock yet, and we've got to come back."

"You'll be out of it by the time I get to the dock," declared Andy.

Indeed it began to look so, for the auto boat was now a full length ahead of Tom's craft and there was open water between them. But our hero knew a thing or two about racing, though he had not long been a motor-boat owner. He adjusted the automatic oiler on the cylinders to give more lubrication, as he intended to get more speed out of his engine. Then he opened the gasoline cock a trifle more and set his timer forward a few notches to get an earlier spark. He was not going to use the maximum speed just yet, but he first wanted to see how the motor of the Arrow would behave under these conditions. To his delight he saw his boat slowly creeping up on Andy's. The latter, with a glance over his shoulder, saw it too, and he advanced his spark. His craft forged ahead, but the rate of increase was not equal to Tom's. "If I can keep up to him I suppose I ought to be glad," thought the young inventor, "for his boat is away ahead of mine in rating."

Through the water the sharp bows cut. There were only a few witnesses to the race, but those who were out in boats saw a pretty sight as the two speedy craft came on toward the dock, which was the turning point.

Andy's boat reached it first, and swung about in a wide circle for the return. Tom decided it was time to make his boat do its best, so he set the timer at the limit, and the spark, coming more quickly, increased the explosions.

Up shot the Arrow and, straightening out after the turn, Tom's craft crept along until it lapped the stern of the Red Streak. Andy looked back in dismay. Then he tried to get more speed out of his engine. He did cause the screw to revolve a little faster, and Tom noted that he was again being left behind. Then one of those things, which may happen at any time to a gasoline motor, happened to Andy's. It began to miss explosions. At first it was only occasionally, then the misses became more frequent.

The owner of the Red Streak with one hand on the steering wheel, tried with the other to adjust the motor to get rid of the trouble, but he only made it worse. Andy's boat began to fall back and Tom's to creep up. Frantically Andy worked the gasoline and sparking levers, but without avail. At last one cylinder went completely out of service.

The two boats were now on even terms and were racing along side by side toward the wooded, point, which marked the finish.

"I'll beat you yet!" exclaimed Andy fiercely.

"Better hurry up!" retorted Tom.

But the young inventor was not to have it all his own way. With a freakishness equal to that with which it had ceased to explode the dead cylinder came to life again, and the Red Streak shot ahead. Once more Andy's boat had the lead of a length and the finish of the race was close at hand. The squint-eyed lad turned and shouted: "I told you I'd beat you! Want a tow now?"

It began to look as though Tom would need it, but he still had something in reserve. One of the improvements he had put in the Arrow was a new auxiliary ignition system. This he now decided to use.

With a quick motion Tom threw over the switch that put it into operation. A hotter, "fatter" spark was at once produced, and adjusting his gasoline cock so that a little more of the fluid would be drawn in, making a "richer" mixture, the owner of the Arrow saw the craft shoot forward as if, like some weary runner, new life had been infused.

In vain did Andy frantically try to get more speed out of his motor. He cut out the muffler, and the explosions sounded loudly over the lake. But it was no use. A minute later the Arrow, which had slowly forged ahead, crossed the bows of the Red Streak opposite the finishing point, and Tom had won the race.

"Well, was that fair?" our hero called to Andy, who had quickly shut off some of his power as he saw his rival's daring trick. "Did I beat you fair?"

"You wouldn't have beaten me if my engine hadn't gone back on me," grumbled Andy, chagrin showing on his face. "Wait until my motor runs smoother and I'll give you a big handicap and beat you. My boat's faster than yours. It ought to be. It cost fifteen hundred dollars and it's a racer."

"I guess it doesn't like racing," commented Tom as he swung the prow of his craft down the lake toward his home. But he knew there was some truth in what Andy had said. The Red Streak was a more speedy boat, and, with proper handling, could have beaten the Arrow. That was where Tom's superior knowledge came in useful. "Just you wait, I'll beat you yet," called Andy, after the young inventor, but the latter made no answer. He was satisfied.

Mr. Swift was much interested that night in his son's account of the race.

"I had no idea yours was such a speedy boat," he said.

"Well, it wasn't originally," admitted Tom, "but the improvements I put on it made it so. But, dad, when are we going on our tour? You look more worn out than I've seen you in some time, not excepting when the turbine model was stolen. Are you worrying over your gyroscope invention?"

"Somewhat, Tom. I can't seem to hit on just what I want. It's a difficult problem."

"Then I tell you what let's do, dad. Let's drop everything in the inventive line and go off on a vacation. I'll take you up the lake in my boat and you can spend a week at the Lakeview Hotel at Sandport. It will do you good."

"What will you do, Tom?"

"Oh, Ned Newton and I will cruise about and we'll take you along any time you want to go. We're going to camp out nights or sleep in the boat if it rains. I've ordered a canopy with side curtains. Ned and I don't care for the hotel life in the summer. Will you go?"

Mr. Swift considered a moment. He did need a rest, for he had been working hard and his brain was weary with thinking of many problems. His son's program sounded very attractive.

"I think I will accept," said the inventor with a smile. "When can you start, Tom?"

"In about four days. Ned Newton, will get his vacation then and I'll have the canopy on. I'll start to work at it to-morrow. Then we'll go on a trip."

Sandport was a summer resort at the extreme southern end of Lake Carlopa, and Mr. Swift at once wrote to the Lakeview Hotel there to engage a room for himself. In the meanwhile Tom began to put the canopy on his boat and arrange for the trip, which would take nearly a whole day. Ned Newton was delighted with the prospect of a camping tour and helped Tom to get ready. They took a small tent and plenty of supplies, with some food. They did not need to carry many rations, as the shores of the lake were lined with towns and villages where food could be procured.

Finally all was ready for the trip and the night before the start Ned Newton stayed at Tom's house so as to be in readiness for going off early in the morning. The day was all that could be desired, Tom noted, as he and his chum hurried down to the dock before breakfast to put their blankets in the boat. As the young inventor entered the craft he uttered an exclamation.

"What's the matter?" asked Ned.

"I was sure I locked the sliding door of that forward compartment," was the reply. "Now it's open." He looked inside the space occupied by the gasoline tank and cried out: "One of the braces is gone! There's been some one at my boat in the night and they tried to damage her."

"Much harm done?" asked Ned anxiously.

"No, none at all, to speak of," replied Tom. "I can easily put a new block under the tank. In fact, I don't really need all I have. But why should any one take one out, and who did it? That's what I want to1now."

The two lads looked carefully about the dock and boat for a sign of the missing block or any clews that might show who had been tampering with the Arrow, but they could find nothing.

"Maybe the block fell out," suggested Ned.

"It couldn't," replied Tom. "It was one of the new ones I put in myself and it was nailed fast. You can see where it's been pried loose. I can't, understand it," and Tom thought rapidly of several mysterious occurrences of late in which the strange man at the auction and the person he had surprised one night in the boathouse had a part.

"Well, it needn't delay our trip," resumed the young inventor. "Maybe there's a hoodoo around here, and it will do us good to get away a few days. Come on, we'll have breakfast, get dad and start."

A little later the Arrow was puffing away up the lake in the direction of Sandport.