"I've thought of that，" said Tom."At worst it can't be any more than looping the loop.But I'll make the muffler 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 assistance 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 hecould see how it is constructed， couldn't he？" asked Ned Newton.
"Yes，" assented 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，" assented 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 mass 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 newnoiseless aeroplane -膍 y Air Scout--I've named that Silent Sam.Wait untilyou 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.
