CHAPTER XXI.--A RASCALLY TRICK.

  While all this had been occurring on the wharf Plumbo Boggs haddiscovered the deception that had been practiced on him, and washastening as fast as he could to the hotel. Even he, whose mind couldnot be called quick acting, realized that he was the victim of a trick,the object of which was, in all probability, to injure the _Sea Eagle_.

  Arousing the night clerk, Plumbo begged to be directed to Dr. Perkins'room. The night clerk knew the eccentric character, and lost no time inescorting him to the doctor's quarters. Plumbo thundered on the doorwith noise sufficient to arouse the other guests.

  "What is it? What's happened?" shouted Dr. Perkins, thinking for aninstant that the place must be on fire at least.

  "Oh, doctor, come quick! They've played us a trick!" yelled Plumbo.

  "Who? Where? What do you mean?" exclaimed Dr. Perkins, coming to thedoor.

  "Two men and a lad; they've fooled me bad."

  "Do you mean that they persuaded you to leave the _Sea Eagle_ alone andunguarded?"

  "They told me a story to get me from there; or I'd have given your airship the best of good care," pleaded Plumbo, seriously alarmed at theangry look that had come over the doctor's face. "Don't be angry withme, I pray; if they hurt it I'll ask you no pay."

  "As if that would help," cried Dr. Perkins angrily; "wait there till Iget some clothes on."

  He retreated into the room and as he hastily donned some garments hewondered who the men could be who had induced the soft-witted poet toleave his position of trust.

  "For the life of me I can't imagine who they can be," he was thinking,while he hurriedly laced his shoes, when the door opened and in walkedHarry fully dressed.

  "I heard the noise in the corridor, and heard Plumbo telling you thatsomething had happened to the _Sea Eagle_," he said excitedly.

  "I don't know that anything has happened yet," cried Dr. Perkinsanxiously; "I'm hoping not. But from what I can gather from Plumbo'sfoolish talk three men induced him, on some pretext, to leave the shipunguarded. I must say it looks suspicious. But I cannot think who thereis in this place where we are unknown who would want to harm us."

  The thought of Duval flashed across Harry's mind. He and Frank haddecided not to tell Dr. Perkins about their encounter lest it shouldworry him; but surely the time to tell about it had come now.

  "We ought to have told you," he said, rather falteringly, "but we didnot want to cause you undue anxiety,--we saw Duval this afternoon."

  "What!"

  Dr. Perkins almost shouted the question, or rather exclamation, in athunderstruck tone.

  "Yes. We tried to catch him, but he escaped us. Frank can tell you allabout it. By the way, where is Frank?"

  "Isn't he in your room?"

  "No; when I was awakened by the noise in the passage I saw that his bedwas empty. I supposed that he had got out of bed ahead of me and hadcome in here."

  "I haven't seen him since we retired."

  "Then where can he be?"

  The inventor and the boy aviator stared at each other for an instant.

  "Good gracious, this looks serious, indeed," exclaimed Dr. Perkins; "notin his room, and not in the hotel, apparently. Where can he have goneto?"

  "That's what's worrying me," cried Harry, in a rather quavering tone;"I'm sure, perfectly sure, that that rascal Duval knows something abouthim wherever he is. Maybe he heard some word of a plot to injure the_Sea Eagle_ and has gone down to see if he can frustrate it. Duval----"

  "Yes; but Duval, if it is he, is not alone in this thing. Plumbo saysthere were two men and a lad."

  "Two men and a lad," cried Harry joyously, "then the lad must have beenFrank."

  "But who could the others have been? They all came together and sent ourwatchman away."

  "It's all a deep mystery, doctor. I think our best plan is to make allthe speed we can to the wharf. Perhaps we can find some solution there."

  "Yes; let us do so at once. I am all ready, are you?"

  "Yes; I hurried to get dressed as soon as I heard the noise in thecorridor."

  Plumbo was waiting, and as they hastened down the street he explained inhis odd rhyming speech just what had happened. He could not describe themen except to say that one had whiskers on his chin. In a part of thecountry where this is a favorite facial adornment this information wasnot much of a clew.

  It took the alarmed party much less time to reach the wharf than theywould have thought was possible. In fact, almost the whole distance wastraversed at a run. But when they arrived at the wharf and a lantern,which Dr. Perkins had had the foresight to bring along, had beenkindled, they found nothing to inform them as to what had taken place.The doctor had not expected to find Plumbo's three men there, but he hadhad an idea that he would find something damaged about the _Sea Eagle_.But as careful an examination as it was possible to make by lamplightfailed to reveal any trace of damage.

  Naturally this, instead of helping to clear the mystery, only deepenedit. What object could the men have had who had sent Plumbo off on hiswild goose chase if it had not been to wreak injury to the _Sea Eagle_?

  "Maybe they were some inventors who wanted to steal your ideas,"suggested Harry, recalling some experiences of their own withunscrupulous aviators.

  But Dr. Perkins shook his head.

  "Every important feature of the _Sea Eagle_ is fully covered bypatents," he said; "there isn't a single idea they could appropriate inthe short time they could have spent here anyhow."

  Harry had to admit that this was so, but to tell the truth his thoughtswere centered more on Frank and on the strange circumstances surroundinghis disappearance than they were on the _Sea Eagle_.

  "I'm as certain as that daylight will come again that Frank fits intothis mix-up somewhere," he said, voicing his thoughts, "but the questionis where?"

  "Well, he's not here now, that's certain," declared Dr. Perkins. "Ipropose that we should return to the hotel now that we have discoveredthat no damage has been done. He may meet us there."

  "Let's search the wharf first," said Harry, but, naturally, even theirpainstaking search failed to reveal any trace of Frank's fate till, allat once, Harry, who was carrying the lantern, came upon his brother'scap lying where it had fallen in the scuffle among the boxes.

  The bit of headgear had been kicked close to the string-piece of thewharf, and a fearful fear that made Harry's head swim shot into hismind. Could Frank have come down to the wharf, suspecting mischief wason foot, and have either fallen or been thrown into the water?

  "Look--look here, sir," he exclaimed in a shaking voice, as Dr. Perkinsasked him what was the matter.

  "What is it?" asked the doctor, coming forward. "A clew?"

  "Yes; it's--it's Frank's cap, doctor. Pray heaven no harm has befallenhim."

  "If it has, swift vengeance is going to overtake somebody," declared Dr.Perkins, clenching his hands; "where did you find the cap?"

  "Close to the string-piece. You--you don't think he could have fallenover?"

  "Nonsense," declared Dr. Perkins with a confidence he was far fromfeeling; "we'll get him back again safe and sound, never fear."

  But Harry's heart sank as he fingered his brother's cap.

  "I'm trying to think so, too, sir," he said miserably; "but--but----"

  He paused abruptly, for he could not have gone further without breakingdown. Harry had gone through some anxious moments in his life, but neverhad his heart sunk so low as it did that night on the Bayhaven wharf.

  In the meantime, let us see how it was faring with the boy whosedisappearance had caused such cruel fears--fears which even the vengefultempers of Daniels and his son would have been satisfied with. We leftFrank gagged and bound on the bottom of the dory, while Zeb and hisfather were pulling with strong, swift strokes for the open water.

  The dory shot swiftly and silently seaward, with Frank completely in thedark as to what was to be his fate. It occurred to him, though, thatperhaps they meant to maroon him on some island.
This thought did notgive him so much anxiety as might have been expected, for he knew thatthe waters about Bayhaven were fairly populous with boats, and did notsuppose that his captors meant to keep him a prisoner any longer timethan would be necessary for them to take their departure from that partof the coast before the authorities could be notified.

  Imagine, then, his thrill of surprise when the boat suddenly stopped andthe barrel, into which some big stones had been thrown to keep itupright in the water, was lowered from the dory. This done, Frank waslifted by main force and placed in it.

  A brutal laugh broke from Zeb and his father as they shoved the barrelcontaining its helpless captive away from the side of the dory. Duvalsaid nothing, but his white teeth showed in a grin in the starlight.Frank, gagged as he was, could not utter a word or move a limb. He couldonly realize, with dumb agony, the terrible nature of his fate.

  Still laughing, the brutal rascals who had conceived the idea of settinghim adrift, rowed off at a quick rate, leaving the barrel and itshelpless occupant bobbing up and down on the swells of the starlit sea.