Tom Swift looked up with a distinct appearance of being annoyed that was unusual with him, for he was, nearly always, good-natured. But the frown that had replaced the pleasant look on his face while he was talking to Mr. Damon about the projected new air scout was at once wiped away as he looked at the card Jackson held out to him.

"Bring him in right away!" he ordered. "He needn't have stood on that ceremony."

"Well, he said it was a business call," returned the mechanician with a cheerful grin, and he said he wanted it done according to form. So he gave me his card to bring you."

"Who is it?" asked Mr. Damon, with the privilege of an old friend.

"It's Ned Newton," Tom answered; "though why he's putting on all this formality I can't fathom."

Jackson went back to the main gate and told the man on guard there to admit Ned, who had so formally sent in his card.

"Ah, Mr. Swift, I believe?" began the bank employee with that suave, formal air which usually precedes a business meeting.

"That is my name," said Tom, with a suppressed grin, and he spoke as stiffly as though to a perfect stranger.

"Mr. Tom Swift, the great inventor?" went on Ned.

"Yes."

"Ah, then I am at the right place. Just sign here, please, on the dotted line," and be held out a blank form, and a fountain pen to Tom, who took them half mechanically.

"Huh? What's the big idea, Ned?" asked the young inventor, unable longer to carry on the joke. "Is this a warrant for my arrest, or merely a testimonial to you. If it's the latter, and concerns your nerve, I'll gladly sign it."

"Well, it's something like that!" laughed Ned. "That's your application for another block of Liberty Bonds, Tom, and I want you, as a personal favor to me, as a business favor to the bank, and as your plain duty to Uncle Sam, to double your last subscription."

Tom looked at the sum Ned had filled in on the blank form, and uttered a slight whistle of surprise.

"That's all right now," said Ned, with the air of a professional salesman. "You can stand that and more, too. I'm letting you off easy. Why, I got Mary's father--Mr. Nestor--for twice what he took last time, and Mary herself--hard as she's working for the Red Cross--gave me a nice application. So it's up to you to--"

"Nuff said!" exclaimed Tom, sententiously, as he signed his name. "I may have to reconsider my recent refusal of the offer of the Universal Flying Machine Company, though, if I haven't money enough to meet this subscription, Ned."

"Oh, you'll meet it all right! Much obliged," and Ned folded the Liberty Bond subscription paper and put it in his pocket. "But did you turn down the offer from those people?"

"I did," answered Tom. "But how did you know about it, Ned?"

"First let me say that I'm glad you decided to have nothing to do with them. They're a rich firm, and have lots of money, but I wouldn't trust 'em, even if they have some government contracts. The way I happened to know they were likely to make you an offer is this," continued Ned Newton.

"They do business with one of the New York banks with which my bank--notice the accent on the my, Tom--is connected. The other day I happened to see some correspondence about you. These flying machine people asked our bank to find out certain things about you, and, as a matter of business, we had to give the information. Sort of a commercial agency report, you know, nothing unusual, and it isn't the first time it's been done since your business got so large. But that's how I happened to know these fellows contemplated dickering with you."

"Do you know Gale or Ware?" Tom asked.

"Not personally. But in a business way, Tom, I'd warn you to look out for them, as they're sharp dealers. They put one over on the government all right, and there may be some unpleasant publicity to it later. But they're putting up a big bluff, and pretending they can turn out a lot of flying machines for use in Europe. Why don't you get busy on that end of the game, Tom?"

"I know you've more than done your bit, with Liberty Bonds, subscriptions to the Y. M. C. A. and other war work, besides your war tank and other inventions. But you're such a shark on flying machines I should think you'd offer your factory to the government for the production of aeroplanes."

"I would in a minute, Ned, and you know it; but the fact of the matter is my shops aren't equipped for the production of anything in large numbers. We do mostly an experimenting business here, making only one or two of a certain machine. I have told the government officials they can have anything I've got, and you know they wouldn't let me enlist when I was working on the war tank."

"Yes, I remember that," said Ned. "You're no slacker! I wanted to shoulder a rifle, too, but they keep me at this Liberty Loan work. Well, Uncle Sam ought to know."

"That's what I say," agreed Tom, "and that's why I haven't gone to the front myself. And now, as it happens, I've got something else in mind that may help Uncle Sam."

"What is it?"

"A silent flying machine for scout work on the battle front," Tom told his friend, and then he gave a few details, such as those he had been telling Mr. Damon.

"Then I don't wonder you turned down the offer of the Universal people," remarked Ned, at the conclusion of the recital. "This will be a heap more help to the government, Tom, than working for those people, even at twenty-five thousand dollars a year. And if you get short, and can't meet your newest Liberty Bond payments, why, I guess the bank will stretch your credit a little."

"Thanks!" laughed Tom, "but I'll try not to ask them."

The friends talked together a little longer, and then Ned had to take his departure to solicit more subscriptions, while Mr. Damon went with him, the eccentric man saying he would go home to Waterfield.

"But, bless my overshoes, Tom!" he exclaimed, as he departed, "don't forget to let me know when you have your silent motor working. I want to see it."

"I'll let you know," was the promise given by the young inventor.

"And watch out for those Universal people," warned Ned. "I'm not telling you this as a bank official, for I'm not supposed to, but it's personal."

"I'll be on the watch," said Tom. And, as he went into his private workshop, he wondered why it was his father and Ned had both warned him not to trust Gale and Ware.

The next few days were busy ones for Tom Swift. Once he had made up his mind to go to work seriously on a silent motor, all else was put aside. He sent a note to Mary Nestor, telling her what he was going to do, and, asking her to say nothing about it, which, of course, Mary agreed to.

"Come and see me when you can," she sent back word, "but I know you won't have much chance when you're experimenting with your invention. And I shall be working so hard for the Red Cross that I sha'n't get much chance to entertain you. But the war can't last forever."

"No," agreed Tom with a sigh, as he put away her letter, "and thank goodness that it can't!"

The young inventor threw himself into the perplexing work of inventing a silent motor with all the fervor he had given to the production of his war tank, his giant cannon, his wonderful searchlight and other machines.

"And," mused Tom, as he sat at his work table with pencil and paper before him, "since this is a problem in acoustics, I had best begin. I suppose by going back to first principles, and after determining what makes an aeroplane engine noisy, try to figure out how to make it quiet. Now as to the first, the principle causes of noise are--"

And at that instant there broke on Tom's ears a succession of discordant sounds which seemed to be a combination of an Indian's war whoop and a college student's yells at a football game.

"Now I wonder what that is!" mused the young inventor as he hastily arose. "Better solve that problem before I tackle the aeroplane motor."