The defect in the motor which had caused Tom Swift to shut off the power and drift down to earth was soon remedied, once the young inventor began an examination of the craft. One of the oil feeds had become choked and this automatically cut down the gasoline supply, causing one or more cylinders to miss. It was a safety device Tom had installed to prevent the motor running dry, and so being damaged.
Once the clogged oil feed was cleared the motor ran as before, and just as silently, though, as Tom had said, he was not entirely satisfied with the quietness, but intended to do further work toward perfecting it.
"I'll start the propellers now, Mr. Damon," said Tom, when the trouble had been remedied. "You know how to throw the switch, don't you?"
"I guess so," was the answer. Mr. Damon and Tom had traveled so often together in gasoline craft that the young inventor had taught his friend certain fundamentals about them, and in an emergency the eccentric man could help start an aeroplane. This he now did, taking charge of the controls which could be operated from his seat as well as from Tom's. Tom whirled the propellers, and soon the motor was in motion.
Mr. Damon, once the big wooden blades were revolving, slowed down the apparatus until Tom could jump aboard, after which the latter took charge and soon speeded up the machine, sending it aloft.
As the green meadow, dimly seen in the light of the moon, seemed to drop away below them, and the clump of trees vanished from sight, both Tom and Mr. Damon wondered who it was that had called for help, and if the matter were at all serious. They were inclined to think it was not, but Tom could not rid himself of a faint suspicion that there might have been trouble.
However, thoughts of his new silent Air Scout soon drove everything else from his mind, and as he guided the comparatively silent machine on its quiet way toward his own home he was thinking how he could best improve the muffler.
"Well, here we are again, safe and sound," remarked Tom, as he brought the craft to a stop in front of the hangar, and Jackson and his helpers, who were awaiting the return, hurried out to take charge.
"Yes, everything seems to point to success, Tom," agreed Mr. Damon. "That is, unless the slight accident we had means trouble."
"Oh, no, that had nothing to do with the operation of the silencer. But I'm going to do better yet. Some day I'll take you for a ride in a silent machine which will make so little noise that you can hear a pin drop."
"Well," remarked Mr. Damon' with a laugh, "I don't know that listening to falling pins will give me any great amount of pleasure, Tom, but I appreciate your meaning."
"Everything all right?" asked Mr. Swift, as he came out to hear the details from his son. "Do you think you have solved the problem?"
"Not completely, but I'll soon be able to write Q. E. D. after it. Some refinements are all that are needed, Dad."
"Glad to hear it. I was a bit anxious."
Mr. Swift questioned his son about the technical details of the trip, asking how the motor had acted under the pressure caused by so completely muffling the exhaust, and for some minutes the two inventors, young and old, indulged in talk which was not at all interesting to Mr. Damon. They went into the house, and Tom asked to have a little lunch, which Mrs. Baggert set out for him.
"It's rather late to eat," said the young inventor, "but I always feel hungry after I test a new machine and find that it works pretty well. Will you join me in a sandwich or two, Mr. Damon?"
"Why, bless my ketchup bottle, I believe I will."
And so they ate and talked. Tom was on the point of telling his father something of the queer cry for help they had heard on the lonely meadow when Mrs. Baggert produced a letter which she said had come for Tom that afternoon, but had been mislaid by a new maid who had been engaged to help with the housework.
"She took it to the shop after you had left, and only now told me about it," explained Mrs. Baggert. "So I sent Eradicate for it."
"How long ago was that?" asked Tom, as he took the missive.
"Oh, an hour ago," answered Mrs. Baggert, with a smile. "But don't blame poor Rad for that. He wanted to deliver the letter to you personally, and so did Koku. The result was your giant kept after Rad, trying to get the letter from him, and Rad kept hiding and slinking about for a chance to see you himself until I saw what was going on, a little while ago, and took the letter myself. Else you might never have gotten it, so jealous are those two," and Mrs. Baggert laughed.
"Guess it isn't of much importance," Tom said, as he tore open the envelope. "It's from the Universal Flying Machine Company, of New York, and I imagine they're trying to get me to reconsider my refusal to link up with them."
"Yes," he went on, as he read the missive, "that's it. They've raised the amount to thirty thousand a year now, Dad, and they say they feel sure I shall regret it if I do not accept.
"This is a bit queer, though," went on the young inventor. "This letter was written three days ago, but it reached Shopton only to-day. And it says that unless they hear from me at once they will have to take steps that will cause me great inconvenience. They have nerve, at any rate, and impudence, too! I won't even bother to answer. But I wonder what they mean, and why this letter was delayed?"
"The mails are all late on account of the transportation congestion caused by moving troops to the camps," said Mr. Damon. "Some of my letters are delayed a week. But, as you say, Tom, these fellows are very impudent to threaten that way."
"It's all bluff," declared Tom. "I'm not worrying. And now, Dad, since I've almost reached the top of the hill with my Air Scout, I may be able to help you on that new electric motor you're puzzling over."
"I wish you would, Tom. I am trying to invent a new system of interchangeable brush contacts, but so far I've been unable to make them work. However, there is no great hurry about that. If you are going to offer your silent machine to the government finish that first. We need all the aircraft we can get. The battles on the other side seem to be all in favor of the Germans, so far."
"We haven't got into our stride yet," declared Mr. Damon. "Once Uncle Sam gets the boys over there in force, there'll be a different story to tell. I only wish—"
At that moment the telephone set up an insistent ringing, breaking in on Mr. Damon's remarks.
"I'll answer," said Tom, as Mrs. Baggert moved toward the instrument, which was an extension from the main one.
"Hello!" called the young inventor into the transmitter, and as he received an answer a look of pleasure came over his face.
"Yes, Mary, this is Tom," he said. He remained silent a moment, while it was evident he was listening to the voice at the other end of the wire. Then he suddenly exclaimed:
"What's that? Tell him to come home? Why, he isn't here. I just came in and—what—wait a minute!"
With a rather strange look on his face Tom covered the mouth-piece of the instrument with his hand, and, turning to his father, asked:
"Is Mr. Nestor here?"
"No," replied Mr. Swift slowly, "He was here, though. He came a little while after you and Mr. Damon started off in the Air Scout. But he didn't stay. Said he wanted to see you about something and would call again."
"Oh," remarked the young man. "I didn't know he had been there."
"I meant to tell you," said Mrs. Baggert; "but getting the lunch made me forget it, I guess."
Tom uncovered the transmitter of the telephone again, and spoke to Mary Nestor.
"Hello," he said. "I was wrong, Mary. Your father was here, but he left when he found I wasn't at home. How long ago? Wait a minute and I'll inquire.
"How long ago did Mr. Nestor leave?" asked the young inventor of the housekeeper. "Nearly an hour," he said into the instrument, after he had received the answer. Then, after listening a moment, he added: "Yes, I guess he'll be home soon now. Probably stopped down town to see some of his friends. Yes, Mr. Damon and I tried out the Air Scout. Yes, she worked pretty well, for a starter, but there is something yet to be done. Oh, yes, now I'll have time to come over to see you, and take you for a ride too. We won't have to talk through a speaking tube, either. Tell your father I am sorry I was out when he called. I'll come to see him to-morrow, if he wants me to. Yes—yes. I guess so!" and Tom laughed, it being evident that his remarks at the end of the conversation had to do with personal matters.
"A telegram has come for Mr. Nestor and they were anxious that he should get it," Tom explained to his little audience as he hung up the receiver and put aside the telephone. "I wonder what he wanted to see me about?"
"He didn't say," replied Mrs. Baggert.
Mr. Damon, Tom, and his father remained in conversation a little while longer, and the eccentric man was thinking that it was about time for him to return home, when the telephone rang again.
"Hello," answered Tom, as he was nearest the instrument. "Oh, yes, Mary, this is he. What's that? Your father hasn't reached home yet? And your mother is worried? Oh tell her there is no cause for alarm. As I said, he probably stopped on his way to see some friends."
Tom listened for perhaps half a minute to a talk that was inaudible to the others in the room, and they noticed a grave look come over his face. Then he said:
"I'll be right over, Mary. Yes, I'll come at once. And tell your mother not to worry. I'm sure nothing could have happened. I'll be with you in a jiffy!"
As Tom Swift hung up the receiver he said:
"Mr. Nestor hasn't reached home yet, and as he promised to return at once in case he didn't find me, his wife is much worried. I'll go over and see what I can do."
"I'll come along!" volunteered Mr. Damon. "It isn't late yet."
"Yes, do come," urged Tom. "But I suppose when we get there we'll find our friend has arrived safely. We'll go over in the electric runabout."
Tom Swift's speedy little electric car was soon at the door in readiness to take him and Mr. Damon to the Nestor home. The electric runabout was a machine Tom had evolved in his early inventive days, and though he had other automobiles, none was quite so fast or so simple to run as this, which well merited the name of the most rapid machine on the road. In it Tom had once won a great race, as has been related in the book bearing the title, "Tom Swift and His Electric Runabout."
"Mary didn't telephone again, did she?" Tom asked his father, as he stopped at the house to get Mr. Damon, having gone out to see about getting the electric runabout in readiness.
"No," was the answer. "The telephone hasn't rung since."
"Then, I guess, Mr. Nestor can't have arrived home," said Tom. "It's a bit queer, his delay, but I'm sure it will be explained naturally. Only Mary and her mother are alone and, very likely, they're nervous. I'll telephone to let you know everything is all right as soon as I get there," Tom promised his father and Mrs. Baggert as he drove off down the road, partly illuminated by the new moon.
Rapidly and almost as silently as his Air Scout Tom Swift drove the speedy car down the highway. It was about three miles from his home to that of Mary Nestor, and though the distance was quickly covered, to Tom, at least, the space seemed interminable. But at length he drove up to the door. There were lights in most of the rooms, which was unusual at this time of night.
The sound of the wheels had not ceased echoing on the gravel of the drive before Mary was out on the porch, which she illuminated by an overhead light.
"Oh, Tom," she cried, "he hasn't come yet, and we are so worried! Did you see anything of father as you came along?"
"No," was Tom's answer. "But we didn't look for him along the road, as we came by the turnpike, and he wouldn't travel that way. But he will be along at any moment now. You must remember it's quite a walk from my house, and—"
"But he was on his bicycle," said Mary. "We wanted him to go in the auto, but he said he wanted some exercise after supper, and he went over on his wheel. He said he'd be right back, but he hasn't come yet."
"Oh, he will!" said Tom reassuringly. "He may have had a puncture, or something like that. Bicyclists are just as liable to them as autoists," he added with a laugh.
"Well, I'm sure I hope it will be all right," sighed Mary. "I wish you could convince mother to that effect. She's as nervous as a cat. Come in and tell us what to do."
"Oh, he'll be all right," declared Mr. Damon, adding his assurances to Tom's.
They found Mrs. Nestor verging on an attack of hysteria. Though Mr. Nestor often went out during the evening, he seldom stayed late.
"And he said he'd be right back if he found you weren't at home, Tom," said Mrs. Nestor. "I'm sure I don't know what can be keeping him!"
"It's too soon to get worried yet," replied the young inventor cheerfully. "I'll wait a little while, and then, if he doesn't come, Mr. Damon and I will go back over the road and look carefully. He may have had a slight fall—sprained his ankle or something like that—and not be able to ride. We came by the turnpike, a road he probably wouldn't take on his wheel. He's all right, you may be sure of that."
Tom tried to speak reassuringly, but somehow, he did not believe himself. He was beginning to think more and more how strange it was that Mr. Nestor did not return home.
"We'll wait just a bit longer before setting out on a search," he told Mary and her mother. "But I'm sure he will be along any minute now."
They went into the library, Mary and her mother, Tom and Mr. Damon. And there they sat waiting. Tom tried to entertain Mary and Mrs. Nestor with an account of his trial trip in the Air Scout, but the two women scarcely heard what he said.
All sat watching the clock, and looking from that to the telephone, which they tried to hope would ring momentarily and transmit to them good news. Then they would listen for the sound of footsteps or bicycle wheels on the gravel walk. But they heard nothing, and as the seconds were ticked off on the clock the nervousness of Mrs. Nestor increased, until she exclaimed:
"I can stand it no longer! We must notify the police—or do something!"
"I wouldn't notify the police just yet," counseled Tom. "Mr. Damon and I will start out and look along the road. If it should happen, as will probably turn out to be the case, that Mr. Nestor has met with only a simple accident, he would not like the notoriety, or publicity, of having the police notified."
"No, I am sure he would not," agreed Mary. "Tom's way is best, Mother."
"All right, just as you say, only find my husband," and Mrs. Nestor sighed, and turned her head away.
"Even if Mr. Nestor had had a fall," reasoned Tom, "he could call for help, and get some one to telephone, unless—"
And as he reasoned thus Tom Swift gave a mental start at his own use of the word "help."
That weird cry on the lonely meadow came back to him with startling distinctness.
"Come on, Mr. Damon!" cried Tom, in a voice he tried to make cheerful. "We'll find that Mr. Nestor is probably walking along, carrying his disabled bicycle instead of having it carry him. We'll soon have him safe back to you," he called to the two women.
"I wish I could go with you, and help search," observed Mary.
"Oh, I couldn't bear to be left alone!" exclaimed her mother.
"We'll telephone as soon as we find him," called Tom to Mrs. Nestor, as he and Mr. Damon again got into the runabout and started away from the place.
"What do you think of it, Tom?" asked the eccentric man, when they were once more on the road.
"Why, nothing much—as yet," Tom said. "That is, I think nothing more than a simple accident has happened, if, indeed, it is anything more than that he has delayed to talk to some friends."
"Would he delay this long?"
"I don't know."
"And then, Tom—bless my spectacles! what of that cry we heard? Could that have been Mr. Nestor?"
There! It was out! The suspicion that Tom had been trying to keep his mind away from came to the fore. Well, he might as well race the issue now as later.
"I've been thinking of that," he told Mr. Damon. "It might have been Mary's father calling for help."
"But we looked, Tom, near the trees, and couldn't discover anything. If he had been calling for help—"
Mr. Damon did not finish.
"He may have fallen from his wheel and been hurt," said Tom, as he turned the electric runabout into the highway that Mr. Nestor would, most likely, have taken on his way from Shopton. "Then he may have called for help, and some autoists, passing, may have heard and taken him away."
"Yes, but where, Tom? Whoever called for help was taken away, that's sure. But where?"
"To some hospital, I suppose."
"Then hadn't we better inquire there? There are only two hospitals of any account around here. The one in Shopton and the one in Waterfield. My wife is on the board of Lady Managers there. We could call that hospital up and—"
"We'll look along the road first," said Tom. "If we begin to make inquiries at the hospitals there will be a lot of questions asked, and a general alarm may be sent out. Mr. Nestor wouldn't like that, if he isn't in any danger. And it may turn out that he has met an old friend, and has been talking with him all this while, forgetting all about the passage of time."
They were now driving along the highway that led from the little suburb where Mr. Nestor lived, to the main part of Shopton, just beyond which was Tom's home. This section was country-like, with very few houses and those placed at rather infrequent intervals. The road was a good one, though not the main-traveled one, and Mr. Nestor, as was known, frequently used it when he rode his bicycle, an exercise of which he was very fond.
As Tom and Mr. Damon drove along, they scanned, as best they could in the light from the young moon and the powerful lamps on the runabout, every part of the highway. They were looking for some dark blot which might indicate where a man had fallen from his wheel and was lying in some huddled heap on the road. But they saw nothing like this, much to their relief.
"Do you know, Tom," said Mr. Damon, when they were nearing the town, and their search, thus far, had been in vain, "I think we're going at this the wrong way."
"Why, so?"
"Because Mr. Nestor may have fallen, and been hurt, and have been carried into any one of a dozen houses along the road. In that case we wouldn't see him. We've passed over the most lonely part of the journey and haven't seen him. If the accident occurred near the houses his cries would have brought some one out to help him. He is well known around here, and, even if he were unconscious and couldn't tell who he was, he could be identified by papers in his pockets. Then his family would be notified by telephone."
"Perhaps you are right, Mr. Damon. We may be wasting time this way. What do you suggest?" asked Tom.
"That we don't delay any longer, but call up the hospitals at once. If he isn't in either of those he must be in some house, and in such condition that his identity cannot be established. In that event it is a case for the police. We haven't found him, and I think we had better give the alarm."
Tom Swift thought it over for a moment. Then he came to a sudden decision.
"You're right!" he told Mr. Damon. "We mustn't waste any more time. He isn't along the road he ought to have traveled in coming from my house to his home—that's sure. But before I call up the hospitals I want to try out one more idea."
"What's that, Tom?"
"I want to go to the place where we heard that cry for help."
"Do you think that could have been Mr. Nestor?"
"It may have been. We'll go and take another look around there. Some man was evidently hurt there, and was taken away. We may get a clew. The lights on the runabout will give us a better chance to look around than we had by the little pocket lamp. We'll try there, and, if we don't find anything, then I'll call up the hospitals."
With the speedy runabout it did not take Tom Swift and Mr. Damon long to reach the place where the Air Scout had been grounded a few hours before, and where they had heard the cry for help. All was as dark and as silent as when they had been there before.
But, as Tom had said, the lights from his electric runabout would give a brilliant illumination, and these he now directed toward the clump of trees whence the cry for help had seemed to come.
"Doesn't appear to have been visited by any one since we were here," remarked Tom, as he observed the marks of the new automobile tire in the dust. "Now we'll look about more carefully."
This they did, but they were about to give up in despair and start for the nearest telephone to call up the hospitals, when Mr. Damon gave an exclamation.
"What is it?" asked Tom.
"Something bright and shining!" said his companion. "I saw it gleam in the light of the lamps. You nearly put your foot on it, Tom. Just step back a moment."
Tom did so, and the eccentric man, with another exclamation, this time of satisfaction, reached down and picked something up from the dusty road.
"It's a watch!" he exclaimed. "A gold watch! And it's been stepped on, evidently, or run over by an auto. Not much damaged, but the case is a bit bent and scratched. It's stopped, too!" he added as he held it to his ear.
"What time does it show?" asked Tom.
"Eight forty-seven," answered Mr. Damon, as he consulted the dial. "Why, Tom, that was just about when we heard the cries for help!"
"Yes, it must have been. Let me see that watch."
No sooner had the young inventor taken the timepiece into his hands than he, too, uttered a cry of amazement.
"Do you recognize it?" asked Mr. Damon, in great excitement.
"It's Mr. Nestor's watch!" cried Tom. "He must have fallen here, and been hurt. It was Mr. Nestor who cried for help, and who was taken away by the autoists. They've probably taken him to some hospital. There's been an accident all right."
Tom and Mr. Damon were of one mind now in thinking that Mr. Nestor had met with some mishap on the road—an automobile accident most likely—and that he was the person who had called for help.
"If they had only answered when we hallooed at them," said Tom, "we wouldn't be in all this stew now. We could have told the strangers who came to his aid who he was, and we might even have taken him to the hospital in the airship."
"Well, it's too late to think of that now," returned Mr. Damon. "We had better get into communication with him as soon as we can, and then send word to his wife and daughter. I hope he isn't badly hurt."
Tom hoped so, too, with all his heart.
There was nothing to do but to get back in the runabout and make all speed for the nearest telephone, and Tom Swift lost little time in doing this. They found a drug store which was open a little later than usual, and at once Tom went into the booth and called up the Shopton hospital. He was well known there, as he and his father were liberal supporters of the institution, which was a private affair. Many of Tom's men were treated at the dispensary, and, as accidents were of more or less frequent occurrence at the works, the young inventor had frequent occasions to call up the place.
"Mr. Nestor would ask to be taken there, as it's nearest his home—that is, if he was able to speak," Tom said to Mr. Damon, who agreed with him. There was a little delay in getting the hospital on the wire, but when Tom had it, and was talking to the superintendent, he was rather surprised, to tell the truth, to be told that Mr. Nestor had not been brought in.
"We haven't had any accident cases all day, nor to-night, Mr. Swift," the superintendent reported. "Was this some one special you were inquiring about?"
For Tom, determining not to give Mr. Nestor's name, except as a last resort, had merely inquired whether any recent accident cases had been brought in.
"I'll let you know later, Mr. Millard," he told the superintendent, not exactly answering the question. He hung up the receiver, and, opening the door of the booth, said to Mr. Damon: "He isn't there."
"Then try Waterfield," was the suggestion; and Tom did so, though he could not imagine why an injured man, such as Mr. Nestor might prove to be, should be taken as far as Waterfield, when the hospital at Shopton was nearer.
"Unless," he told Mr. Damon, "the people which ran down Mary's father didn't know about our hospital."
The reply from the institution in Mr. Damon's home town was just as discouraging as had been the answer from Shopton. At first, when Tom inquired, the head nurse had said there was an accident case at that moment being brought in. Tom was all excitement until she went to inquire the name and circumstances, and then he learned that it was the case of a little boy who had fallen downstairs at his home and broken a leg. There was no record of any one answering the description of Mr. Nestor having been brought in that evening.
"Hum! This is getting to be mysterious," mused Tom, as he came out of the booth. "What shall we do—go back and tell Mrs. Nestor and Mary, or communicate with the police?"
"Why not try the Alexian Hospital?" asked Mr. Damon. "That's away over in Centerford, to be sure, but it's more likely to be known to passing tourists than either of our institutions around here, especially if the autoists were strangers."
"That's so," agreed Tom. The Alexian Hospital was operated under the direction of the Brothers of that faith, and was well known in that part of the state. Often cases of persons who had been injured by passing automobiles had been taken there for treatment, for, as Mr. Damon had said, it was well known, and Centerford was the nearest large city.
"I can just about see how it happened," said Tom. "They ran Mr. Nestor down, and stopped to pick him up after they heard his cries for help. And the Alexian Hospital was the first one they thought of. We should have called that up first."
But once more disappointment awaited the young inventor and his friend. Word came back over the wire that no accident case, which bore any resemblance to Mary's father, had been brought in.
"Well, I'm stumped!" exclaimed Tom. "What shall we do now, Mr. Damon?"
"Much as I dislike it," said the eccentric man who was too much worried, now, to do any "blessing," which was his favorite expression, "I think we ought to communicate with Mrs. Nestor. She will be very anxious."
"I guess we'll have to," said Tom. "But wait! I'll call up my house first, and see if he has gone back there."
But Mr. Nestor had not done this, and Mrs. Baggert, who answered the telephone, said Mary had been calling frantically for Tom, as her mother was now on the verge of complete collapse.
"No help for it," said Tom, ruefully. "We've got to tell 'em we have no news, and can't find him."
And, hearing this, Mrs. Nestor did collapse, and a doctor was called in.
Thereupon Tom, who with Mr. Damon had gone back to the Nestor home, took charge of matters, sending for Mrs. Nestor's sister to come and stay with her and take charge of the house.
"You'll need some one to stay with you," he told Mary.
"Yes, I shall," she admitted, trying bravely not to give way to her emotion. "Oh, Tom, I wish you could stay, too. I'm sure something dreadful must have happened to poor father. Please stay and help us find him!"
"I will," Tom promised. "As soon as your aunt comes I'll take Mr. Damon home, and then I'll give the rest of my time to you."
And this Tom did, sending word home that he would remain at the Nestor's all night and part of the next day.
Tom got but little sleep that night. He communicated with the police and saw to it that a general alarm was sent out. He called up all hospitals within a radius of fifty miles, but could get no trace of any injured man whose description resembled that of Mr. Nestor.
"What can have happened?" asked Mary tearfully.
"Well, the way I figure it out is this," said Tom. "Your father left my house soon after Mr. Damon and I did in the Air Scout. Mr. Nestor was riding his bicycle, and he must have been run into by an automobile. That is how his watch was damaged and that was when Mr. Damon and I heard the cries for help."
"Oh, do you think he was badly hurt?" asked Mary.
"No, I don't," and Tom answered truthfully. "The voice sounded as though he was in pain, certainly, but it was strong and vigorous, and not at all as though he was dangerously hurt."
"And what do you think happened to him after he was hurt?" asked Mary.
"The autoists took him away," decided Tom. "In fact, we heard the machine go, but of course we never connected the call for help and what followed with your father. The autoists took him away."
"Where?"
"I should say to some hospital. Perhaps a private one of which we know nothing, and which may be near here. I'll get a full list from the Board of Health to-morrow. Or it may be that the autoists, seeing the damage they had done, took your father to the home of one of themselves, and summoned a doctor there."
"Why would they do that?"
"Well, they may have been so frightened they didn't realize what they were doing, or they may have thought he would get better treatment in a private house, if he were not badly injured, than if he should be taken to a hospital. It may have been that one of the persons in the auto was a physician, and wished to try his own skill on the man he had hurt."
"You make me feel more comfortable, Tom," said Mary. "But, even supposing all this, why couldn't they telephone to us that my father was all right? He always carries an identification card with him, and if he were unconscious it could be ascertained who he was."
"That's what I can't understand," said Tom frankly. "It puzzles me. But we'll find him—never fear!"
And so he kept on with his telephone inquiries, while a physician and her sister ministered to Mrs. Nestor. The night was very, very long, and no good news came in.
Slowly the dawn broke through the mists of darkness, and made the earth light. The sun came straggling in through cracks in the shutters in the home of Mr. Nestor, the gradually increasing gleam paling the electric lights, in the glare of which Tom Swift, Mary, and her aunt sat, waiting for some word of the missing man. But none came.
"What shall we do now?" asked Mary, as she looked at Tom.
"Oh, there's lots to do," he said, trying to make his voice sound cheerful. "We'll be busy all day. I sent word to have one of my touring cars ready to hurry to any part of the country the moment we should get word from your father."
"And do you think we shall get word, Tom?" the girl went on wistfully.
"Of course we shall!" he cried. "Word may come in at any time. Now get ready, eat a good breakfast, and then you can go with me as soon as we hear anything definite. Come, we'll have breakfast!"
"I can't eat a thing!" protested Mary.
"Oh, yes you can," said her aunt, who was a cheerful sort of person. "I'll see about getting something for you and Mr. Swift, and see that your mother is all right."
She left the room to give orders to the servant about the meal, and returned to say that Mrs. Nestor was sleeping quietly. She had been given a sedative. Mary managed to eat a little, and she gave Tom the address of several friends who were called up in the vain hope that, somehow, Mr. Nestor might have gone to see them.
"Tom, what do you really think has happened?" asked Mary again, as they sat facing one another in the library, during a respite from the telephone.
Tom Swift repeated, to the girl his theory of what had happened with an assumption of confidence he did not altogether feel.
His prediction of a speedy end to the suspense did not come true that day, nor for many days. No news was heard of Mr. Nestor. After the first day, when there was no information and when no reports came of any one of his description having been hurt in an automobile accident or having been taken to any hospital, the police started an energetic search.
The authorities in all near-by cities were notified, and all thought of keeping from the public what had happened was given over. Tom's story, of how he and Mr. Damon had heard the cry for help on the lonely meadow, was printed in the papers, though the young inventor did not say that he had been out trying his new aeroplane. That was a detail not needed in the finding of Mr. Nestor.
But Mary's father was not found. The mystery regarding his disappearance deepened, and there was no trace of him after he had left Tom's house that eventful evening. Persons living along the roads he might have taken in riding his bicycle were questioned, but they had seen nothing of him, nor were they aware of any accident. Tom's testimony and that of Mr. Damon was all the clew there was.
"I don't believe he's dead!" stoutly declared the young inventor, when this dire possibility had been hinted at. "I believe the persons who were responsible for the accident are afraid to reveal his whereabouts until he recovers from possible injuries. You'll see! Mr. Nestor will come back safe!"
And, somehow, though her mother was skeptical, Mary believed what Tom said.
The search was kept up, but without result, and Tom aided all he could. But there was not much he could do. The police and other authorities were at a total loss.
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 muffler 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 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 he could 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 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.