Tom Swift and His Air Scout Part 19

In the intervals of visiting Mary and her mother, and doing what he could for them, Tom worked on his new motor. He knew that he was on the right track and that all that was needed now was to make certain refinements and adjustments in the apparatus he had already constructed, so that it would operate more quietly.

"Absorbing the vibrations from the exhaust, caused by the exploded gases in the cylinders, does the trick," Tom told his father.

"But there is enormous pressure to overcome, Tom. You must be sure your m.u.f.fler will stand the strain. Otherwise she is going to blow out a gasket some day, when you least expect it. Then the sudden resumption of pressure outside the cylinders is going to cause a change in the equilibrium, and you may turn turtle in the air."

"I've thought of that," said Tom. "At worst it can't be any more than looping the loop. But I'll make the m.u.f.fler doubly strong."

"Better provide an auxiliary chamber to take care of part of the exhaust in case your main apparatus breaks," advised the older inventor, and Tom said he would. He did, too, for he valued his father's expert advice.

Meanwhile he was busy fitting one of his latest aeroplanes with the new motor. The motor he and Mr. Damon had used in their flight was one patched up from an old one. But now Tom was working on a complete new one, made after his revised model, and in which the silencer was an integral part, instead of being built on.

While giving Mary and her mother all the a.s.sistance in his power, Tom still found time to work on his new, pet scheme. He had matters now where he did not fear any tampering with his plans, for he had filed away his papers in a safe place, and was making his new machine from memory.

"But if some one got in and had a look at the inside of your silencer he could see how it is constructed, couldn't he?" asked Ned Newton.

"Yes," a.s.sented Tom, "But they're not going to get in very easily. Koku sleeps in the experiment shop now, and my machine is there."

"Oh, well that explains your confidence. I feel sorry for the burglar who makes the attempt, once Koku wakes up. Heard anything more from those Universal people?"

"No, not directly. I understand they are working hard on some new type of plane for army use, but I haven't bothered my head about them. I'm too much occupied with my own affairs and trying to help Mary."

"Very strange about Mr. Nestor, isn't it?"

"Worse than strange," said Tom. "If this keeps on, and he isn't heard from, it will be tragic pretty soon."

"He must be held a prisoner somewhere," declared Ned.

"It begins to look that way," a.s.sented Tom. "Though who would have an object in that I can't understand. He had no enemies, as far as is known, and his business affairs were in excellent shape. Unless, as I said, the persons who ran him down are, through fear, keeping him hidden until he recovers, I can't imagine what has become of him."

"Well, it certainly is a puzzle," said Ned. And Tom agreed with his chum.

It was about a week after the disappearance of Mr. Nestor that Mr.

Damon came over to see Tom.

"Bless my shoe laces, Tom!" exclaimed the eccentric man, "but you are as busy as ever." For he found the young inventor in the experiment shop, surrounded by a ma.s.s of papers and all sorts of mechanical devices.

"Yes, I'm working a little," said Tom. "But you are just in time. Come on out, I want to introduce you to Silent Sam."

"'Silent Sam!'" exclaimed Mr. Damon. "Have you been taking a new trip to the Land of Wonders? Have you brought back some new kind of servant?"

"Not exactly a servant," said Tom with a laugh, "though I hope Silent Sam will serve me well."

"'Silent Sam?' What does it mean? Is that a joke?" asked the puzzled Mr. Damon.

"I hope it doesn't turn out a joke," replied Tom. "But come on, I'll introduce you to him, Mr. Damon."

He led the way to one of the big hangars where his various machines of the air were housed. On the way Mr. Damon asked about news of Mr.

Nestor, but was told there was none.

Tom Swift opened the big, swinging doors and pulled aside an enveloping canvas curtain. There stood revealed a big aeroplane, of somewhat new pattern, the wings gleaming like silver from the varnish that had been applied. In shape it was not unlike the machines already in use, except that the propellers were of somewhat different design.

The engine was mounted in front, and even with his slight knowledge of mechanics Mr. Damon could tell that it was exceedingly powerful. But it was certain devices attached to the engine that attracted his attention, for they were totally different from any on any other aeroplane, though they bore some resemblance to apparatus on the plane in which Tom and the eccentric man had made the night flight.

"Is this your new machine, Tom?" asked Mr. Damon.

"Yes."

"Well, I don't see anything of that fellow you spoke of--Silent Sam."

"This is Silent Sam," returned Tom, with a laugh. "I've named my new noiseless aeroplane--my Air Scout--I've named that Silent Sam. Wait until you hear it, or rather, don't hear it, and I think you'll agree with me. Silent Sam for Uncle Sam!"

"Good!" cried Mr. Damon. "Bless my dictionary, but that's a good name!

Does it sail silently, Tom?"

"I'll let you judge presently. Silent Sam is all ready for his first trial, and I'll be glad to have you with me. Now, I'll just--"

Tom suddenly ceased speaking and held up a hand to enjoin silence.

Then, while Mr. Damon watched, the young inventor began moving noiselessly toward the rear of the big shed, inside which was his new machine.

CHAPTER XVIII

SUSPICIONS

"Who's there?" suddenly called Tom, and in such a sharp voice that Mr.

Damon started, ready as he was for something unusual.

There was no answer and Tom suddenly switched on all the lights in the shed. Up to then there had been only a few glowing--just enough for him to show the new Air Scout to his friend.

"Who's there?" asked Tom again, sharply.

"Bless my opera gla.s.ses, Tom!" cried Mr. Damon, "but are you seeing things?"

"No; but I'm hearing them," answered Tom with a short laugh. "Did you think you heard some one moving around near the rudders of Silent Sam, Mr. Damon?"

"No, I can't say that I did. Everything seems to me to be all right."

"Well, it doesn't to me," went on Tom grimly. "I think there is an intruder in this shed, though how any one could get in when the doors have been locked all day, is more than I can figure out. But I'm going to have a look."

"I'll help you," offered Mr. Damon, and, in the bright glare from many electric lights, the two began a search of the big hangar where the new craft was kept.

But though the young inventor and his friend went around to the rear of the aeroplane, walking in opposite directions, they saw no one, nor did any one try to escape past them.

"And yet I was sure I heard some one in here," declared Tom, when a search had revealed nothing. "It sounded as if some one were scuffling softly about in rubber-soled shoes, trying to hide."