For perhaps a quarter of a minute Tom Swift and the president of the Universal Flying Machine Company of New York sat staring at one another. Mr. Gale's face wore a puzzled expression, and so did Tom's. And, after the last remark of the young inventor, the man who had called to see him said:

"Well, perhaps we are talking at cross purposes. I don't blame you for not feeling very friendly toward us, and if I had had my way that last correspondence with you would never have left our office."

"It wasn't very business-like," said Tom dryly, referring to the veiled threats when he had refused to sell his services to the rival company.

"I realize that," said Mr. Gale. "But we have some peculiar men working for us, and sometimes there is so much to do, so many possibilities of which to take advantage, that we may get a little off our balance. But what I called for was not to renew our offer to you. I understand that is definitely settled."

"As far as I am concerned, it is," said Tom, as his caller seemed to want an answer.

"Yes. Well, then, what I called to say was that if you are thinking of taking any legal action against us because of the action of that man Lydane, I wish to state that he had absolutely no authority to--"

"Excuse me!" broke in Tom, "but by Lydane do you mean the man who also posed as Bower, the spy?"

"No, I do not. Though I regret to say that Bower once worked for us. He, too, had no authority to come here and get a position. He was still in our service when he did that."

"So I have suspected," said Tom. "I realize now that he was a spy, who came here to try to find out for you some of my secrets."

"Not with my permission!" exclaimed Mr. Gale. "I was against that from the first and I came to tell you so. But Bower really did you no harm."

"No, he didn't get the chance!" chuckled Tom. "Nor did that other spy--the one with the gold tooth. I wonder how he liked our mud hole?"

"He was Lydane," said Mr. Gale. "It is about him I came."

"You might have saved yourself the trouble," returned Tom. "I don't wish to discuss him."

"But I wish to make sure," said Mr. Gale, that what he has done will not come back on us. We repudiate him entirely. His methods we can not countenance. He is too daring--"

"Oh, don't worry!" interrupted Tom. "He hasn't done anything to me--he didn't get the chance, as I guess he's told you. You needn't apologize on his account. He did me no harm, and--"

"But I understood from him that--"

"Now I don't want to seem impolite!" broke in Tom, "nor do I want to take pattern after some of your company's acts, if not your own. But I am very busy. I have an important test to make for the government, and my time is fully occupied. I am afraid I shall have to bid you good-morning and--"

"But won't you give me a chance to--" began the president.

"Now, the less we discuss this matter the better!" interrupted Tom. "Lydane, as you call the man with the gold tooth didn't really do anything to me nor any great harm to any of my possessions, as far as I can learn. His career is a closed book-- a book with muddy covers!" and the young inventor laughed.

"Oh, well, if you look at it that way, there is nothing further for me to say" said Mr. Gale stiffly. "I understood-- But hasn't my partner, Mr. Ware, seen you?" he asked Tom quickly.

"No. And I don't care to see him."

"Oh, then that accounts for it," was the quick answer. "Well, if you regard the matter as closed I suppose we should also. We are not to blame for what Lydane does when he is no longer in our employ, and we repudiate anything he may do, or may have done."

This struck Tom, afterward, as being rather a queer remark, but he did not think so at the time.

The truth was that the young inventor wished very much to try out a new device on his noiseless aeroplane and wanted to get rid of Mr. Gale before doing so. So he did not pay as much attention to the remarks of the president as, otherwise, he might have done.

It was not until after Mr. Gale had taken his leave and Tom had finished the particular work on which he was engaged when the president of the rival company came in, that the young man did some hard thinking. And this thinking was done after he had received a telephone call from Mary Nestor, asking, if by any chance, he had beard anything like a clew as to the whereabouts of her father.

Tom had been obliged to tell her that he had not. Everything possible was being done to find the missing man but he had disappeared as completely as though he had ridden on his bicycle into the crater of some extinct volcano on the meadow, and had fallen to the bottom.

An effort was made to trace him through an automobile association which had a large membership. That is, the members were asked to make inquiries to ascertain, if possible, whether any one had heard of an unreported accident--one in which Mr. Nestor might have been carried away by persons who accidently ran him down.

But this came to naught, and the police and other authorities were at a loss how farther to proceed. It was a theory in some quarters that Mr. Nestor was perfectly safe, but that he was out of his mind, and was either wandering around, not knowing who he was, or was, in this condition, detained somewhere, the persons having him in charge not realizing that he was the missing man so widely sought.

This belief was a relief to Mrs. Nestor and Mary in many ways for it prevented them from giving way to the fear that Mr. Nestor was dead. That he was alive was Tom Swift's firm opinion, and he was doing all he could to prove it.

It was not until the day after the visit of Mr. Gale that Tom, having concluded some intricate calculations about the strength of cylinder valves, uttered an exclamation.

"I wonder if he could have meant that?" cried the young inventor. "I wonder if he could have meant that? I must find out at once! Queer I didn't think of that before!"

He put in a long distance call to New York, asking to speak to Mr. Gale. But when, eventually, he was connected with the office of the Universal Flying Machine Company he was told that Mr. Gale and Mr. Ware had sailed for France that day, going over as government representatives to investigate aeroplane motors. Gale's visit to Tom had been just previous to taking the boat, it was said.

"This is tough luck!" mused Tom, his suspicions doubly aroused now. "I can't let this rest here! I've got to get after it! As soon as I make this final test, and invite Uncle Sam's experts out to see how my noiseless motor works, I'll get after Gale and Ware if I have to follow them to the battlefields of France! I wonder if it was that he was hinting at all the while! I begin to believe it was!"

Tom Swift had decided on another flight for his new craft before he would let the government experts see it.

"Silent Sam must do his very best work for Uncle Sam before I turn him over," said the young inventor.

"And after this flight I'll offer the machine to the government, and then devote all my time to finding Mr. Nestor," said Tom. "I'd do it now, but private matters, however deeply they affect us, must be put aside to help win the war. But this will end my inventive work until after Mr. Nestor is found--if he's alive."

Preparations for the test flight went on apace, and one afternoon Tom and Jackson took their places in the big, new aeroplane. He no longer feared daylight crowds in case of an accident. They made a good start, and the motor was so quiet that as Tom passed over his own plant the men working in the yard, who did not know of the flight, did not look up to see what was going on. They could not hear the engine.

"I think we've got everything just as we want it, Jackson," said Tom, much pleased.

"I believe you," answered the mechanician. "It couldn't be better. Now if--"

And at that moment there came a loud explosion, and Silent Sam began drifting rapidly toward the earth, as falls a bird with a broken wing.