Several breakdowns of the engine had delayed them, so that they were even now two days behind time. On this account, as well as through prudence, they meant to stop here as briefly as possible.

Immediately their purser went ashore to make inquiries, and purchase a lot of fruits that could be taken on the river voyage; though for that matter they might expect to get anything they wanted at various villages along the route.

Frank was looking the crowd over closely.

"I think I see him, Andy," he remarked, presently.

"You mean Senor Jose?" asked his cousin, eagerly. "I've been watching that middle-aged gentleman who seems to be pressing close in on the flank of the crowd. There, see, he is speaking to Manuel, our purser, now, asking him some question. He looks up here at us; yes, and waves his hand, with a smile! That must be Senor Jose, all right, Frank."

"I'm going down to meet him, to fetch him aboard," declared Frank, after both boys had answered the signals of the dark-faced gentleman in the white linen suit, and who was also wearing a Panama straw hat.

Three minutes later and Frank reappeared, having the other in tow.

Just as both of them had suspected it was Senor Jose. Receiving their communication from Maracaibo, he had been on the watch.

"And he tells me, Andy, that there has been no new development since he wrote. So that fear of yours must be set at rest. Just depend on it, we're in this game to win out, and your dear father is going to be found," Frank went on.

Presently they were deep in conversation. The boys found Senor Jose a very intelligent gentleman indeed. He had spent some years in Washington in connection with the embassy of his government, so that he not only spoke and wrote English well, but had a high opinion of Americans; something that the vast majority of his fellow-countrymen failed to acquire, being possibly fed on stories that may have had their inception in German or English trade sources.

From him Frank extracted all the information he could concerning the wonderful country lying between Magangue and the Isthmus of Panama, covering possibly some three hundred miles. It was little enough. Most of it, he declared was a terra incognita, being utterly unknown land.

"But," continued the obliging senor, "you will certainly be able to learn more concerning this when you see my fellow-countryman, Senor Mendoza; for all his life has he lived there at Magangue, and surely he must know something of that country to the south."

"We shall leave here with as little delay as possible," observed Frank. "I have sent our purser, Manuel, to comply with the custom duties, and secure us a few supplies. When he comes aboard again we expect to start."

"It is just as well," remarked the other, significantly, and seeming to be relieved. "Because, there is an uneasy feeling in Barranquila just at present. Agents of the revolutionary junta have been here. They are very active. And from secret sources I happen to know that they are aware of the strange cargo you are bringing with you."

"You must mean our aeroplane, Senor?" remarked Frank, quickly.

"Si, Senor Bird," the other continued, nodding his head. "It has become known that the two young Americanos are of the new and wonderful aeronauts, with whom nothing is impossible. And if you remained here any length of time I fear lest even my government might seek to find some excuse for appropriating your little airship. The talk is all in that direction now. Colombia is ripe to take a forward step, and have an aviation corps."

"Well," said Frank, "under the circumstances we would seriously object to having our monoplane confiscated now, because upon it we depend wholly in our search. But I thought you were perhaps about to warn us to look out for these revolutionists while passing up the river."

"It would be wise, Senor," observed the amiable Colombian ex-diplomat. "They have agents here; and I happen to know that one is even now on the wharf, observing. Possibly he seeks to communicate with some spy who chances to be a member of your crew. So you see, it must pay you to be always on your guard, and prepared!"



CHAPTER X.

NIPPED IN THE BUD.

"There comes Manuel!" remarked Andy, after they had been nearly an hour talking on the deck of the little power boat.

"Yes," remarked his cousin, who was also on the watch, "and trailing behind him I can see several native carts containing fruits and new supplies. Manuel surely means that we shall not go hungry while on the river."

"Then I shall be going, my friends," said Senor Jose. "I have told you all I know. I have warned you to beware of the revolutionists along the river bank. I have even given you a hint that to delay longer in Barranquila might endanger your enterprise; since the government is just now very anxious to acquire such wonderful modern agents of warfare, as your aeroplane. It only remains to shake your hands, both, amigos, and wish you every good fortune your valor deserves."

They squeezed the hand of the fine old Colombian gentleman with vigor. Never would Andy forget how he had spoken concerning his interest in the sacred duty that had brought the son of the missing aeronaut to his country.

Frank had given strict orders that none of the crew should go ashore, and also that no strangers be permitted to board the craft while they lay there at the old wooden wharf.

"But," said Andy, when they were speaking about this matter, as preparations began to leave the port, "that hasn't prevented the crew from holding an animated confab with those ashore. There has been a constant jabbering and laughing between our fellows and those others."

"Yes," admitted Frank, "and I've seen several of the crew talking mysteriously with some of those chaps. I wish now the senor had thought to indicate which was the secret agent of the revolutionists he saw on the dock. But all the same I've marked the two fellows I suspect, and I'm going to keep a close eye on Enrique, and the little fellow with the quick motions we call 'Cospita,' because he's forever ejaculating like that."

"And if you find out that they're meddling with the boxes?" asked Andy.

"H'm! I guess it'll be a bad day for Enrique and the jumping-jack, that's all," laughed his cousin. "But there goes the cable, and it looks like we might be off at last."

"I'm not sorry, for many things!" declared Andy, with a sigh of positive relief. "The good senor got me scared by what he said about his government wanting just such things as our little 'Bug'; and that the officials might have orders to find some sort of ridiculous excuse for grabbing it."

"Same here," admitted Frank. "In fact, that bothered me a whole lot more than the chances of trouble along the river from the boys who want to get their man seated in the president's chair, where he could hand out the loaves and the fishes. We can resist them, and be backed by authority; but if the government officers once took us in we'd have to give up our job. And that would break your heart, Andy."

"Yes," said the other, drawing a long breath, "I'm afraid it would. Listen! There goes the whistle. I told the pilot not to make more fuss than he could help when we drew out."

"Which was quite right. I'm watching that little chap, Cospita. See him wave his hand to some one ashore? Yes, and that surely looked like a signal the fellow returned. We are going to have trouble with that boy yet, Andy."

"Well, that will be bad for Cospita," was all the other remarked; for he was eagerly watching the growing space between the boat and the shore.

"Look, Frank," he remarked, after a little time had elapsed, "as sure as you live, there is an officer in uniform just arrived on the dock, and backed by a squad of soldiers! He seems to be surprised at discovering that we have gone! Now he beckons, and waves his hat! Listen to him shouting something in Spanish through his hands. I guess we didn't get away from Barranquila five minutes too soon!"

"It looks like it," said Frank, grimly. "But we've complied with the law of the land, and nothing short of a cannon could make us turn back now. All the same, I'm going to the pilot house, and keep an eye on Felipe. I think he's trustworthy; but an ounce of prevention is better than a pound of cure always."

"Good for you!" Andy shot after his departing chum; though he himself remained there by the rail, watching what took place ashore.

Frank quickly entered the pilot house. Here a dark-faced, middle-aged man handled the wheel. Frank immediately noticed that he was listening to what the gold braided officer ashore was shouting angrily. He also looked a bit troubled.

"What does he say, Felipe?" demanded the young aviator.

"He commands us to return, senor," replied the other.

"Well, pay no attention to him, Felipe. We have complied with all the regulations and red tape necessary. The American consul will back us up. It is your business to simply steer this boat up the river until we arrive at Magangue."

"Si, senor. But when I return they will surely make the trouble for me," replied the pilot, shrugging his narrow shoulders.

"Not at all, Felipe," declared Frank. "You can swear that we made you do as we wished; that you dared not turn back, since your life was in danger. We stand ready to shoulder all the blame there is."

The dusky face of the old river pilot, whom they had fortunately run across in Maracaibo, became wreathed in a smile.

"Perhaps the young senor would not mind showing the Capitan?" he suggested.

Frank grasped his meaning; and pretending to scowl darkly, he drew out the revolver which Colonel Josiah had made him promise to carry while down in this explosive country.

"Now, Felipe," he said, as he clapped the weapon deliberately against the head of the pilot, "your gay Capitan can easily see what I am doing, and will understand what it means. You keep right on up-river; and if you dare disobey it will be bad for you, Felipe!"

The shrewd old pilot tried to smother an expansive grin as he replied:

"Si, senor, I am in your hands; do with me what you will. I dare not refuse longer. See, I have made one effort to turn about; but you threaten, and I give it up. He no longer calls. He knows old Felipe is powerless. It is well!"

Frank stood by him until the wharf was dimmed by distance. Then he hastened to rejoin his cousin and chum, who was mightily pleased to hear all about it.

"Do you think they will chase after us?" queried Andy, still worried.

"Oh! I guess not. It isn't so serious as all that. They know they can get us when we come down the river, no doubt," replied Frank, carelessly.

"Then I'll care precious little what becomes of the Bug," observed Andy, with a sigh of relief.

"I suppose you mean that by that time you'll either have found your father; or else given up the search as hopeless. Is that it, old fellow?" Frank asked.

"Yes, one or the other. And now, we've got time to remember the other warning good old Senor Jose gave us."

"About the revolutionists trying to stop us on the way and get our cargo? Yes," Frank went on, "that must be on our minds constantly. I'm going to talk with old Felipe about it soon. I have a hunch that he can be depended on to back us up, for he's got a grudge against the man these fellows want to send back into the presidential chair. Senor Jose told me Felipe lost all his family through the persecution of that man and his party."

"A bully good thing to know," assented Andy. "For we can be dead sure of Felipe all the time; and through him get pointers about the rest of the crew. There are a few goats among the sheep, and when we make sure of it, I'm just going to pay them off, and chuck them ashore in any old place."

"Now that's what I call a clever scheme," Frank declared. "They would have no kick coming, because, you see, no Spanish American could ever complain of getting his wages without having to do any work!"

"I guess not," Andy remarked, grinning assent.

Upon further conference it was decided to divide the day and night into watches, so that one of them could be on deck and alert all of the time, while the other secured some sleep.

Treachery, they knew, would be likely to crop out during the night time. Those on board may have found some means of telling their confederates ashore about what time the boat would reach a given point. And by means of some native method of telegraphing, such as by means of wigwag flags, or "smokes," the news could be hurried up the river much in advance of the vessel that was butting against the strong current of the swollen Magdalena.

Then Frank went forward to have a long talk with the trusty pilot. He took Felipe into his confidence, telling him for the first time all about their sacred mission to this region of Colombia. And in this way, as well as by promising to double his regular wages, Frank quite won the old fellow's heart.

In return Felipe was able to give his employer considerable valuable information connected with the crew. Frank mentioned no names, and hence he was satisfied that he had made no mistake in his calculations, when among the list of "suspects" given by the pilot, both Enrique and little "Cospita" were included.

"We must get rid of them both as soon as possible," he announced. "So just before night sets in, draw the boat to shore near some village or town. Then I shall pay both men off, get their signatures to the fact, and insist on their going ashore. Meanwhile, as you find opportunity, post a few of the faithful ones to the fact that we suspect them of being insurrectoes."

Felipe declared that the idea was superb. He was growing more and more fond of these venturesome young Americanos, who were so generous, so brave, and who had come all this great distance, actuated by such a noble purpose. So many a man may easily feel when his salary has been unexpectedly doubled.

During the balance of that afternoon the two young aviators continued to alternately sit upon the deck, and wander about the boat, watching things. Frank had the precious aeroplane locked up in the spacious lazerette, which being also used as a storeroom for extra supplies, that the circumstance need not be looked upon as singular.

"I'm determined that no ill may happen to that machine, if I can help it," he said to his chum, when speaking of what he had had done.

And Andy, of course, fully endorsed his course.

So the sun began to draw closer to the western horizon, represented by the distant mountains where the chief inland town of the province, Sabanalarga, lay.

Felipe had spoken of a place on the eastern bank of the river, where they could draw in, and put the two suspects ashore. And Frank told Andy to back him up in what he was about to do.

"There's the town ahead, only a little place, but it answers our purpose, for they can never say we deserted them in the howling wilderness," and Frank, who had been counting out some money, started to make his way down to the waist of the vessel, where most of the crew had gathered, wondering what the object of the landing might be.

Enrique and "Cospita" were surely very much astonished and alarmed when told that their services were needed no longer—that it was ascertained they were carrying too many men; and also that they were to receive full pay for the time they had engaged.

Of course they started to make objections, and the air was filled with various excited exclamations; but Frank proved as firm as adamant, and showed the automatic revolver sticking from his pocket all the while, a fact that kept the two men from venturing to do more than shout.

Clutching their money they were pushed ashore by members of the crew, who doubtless could give a pretty good guess as to what the whole thing meant, since they had talked with Felipe.

"A good riddance of bad rubbish!" declared Andy, as the boat again started up the river, leaving a pair of yelling natives behind, making all sorts of furious gestures with both arms.

"Yes," pursued Frank, reflectively, "and if we wanted any more evidence that we nipped a conspiracy to seize the vessel in the bud, there it is in their anger at being paid for not working. Nothing like that was ever known before down in this country, as Felipe says. And now, Andy, I feel that we're another step nearer the carrying out of your great task."

"Oh! I hope so," said the other, his face marked by an eagerness that told of the one sole wish of his youthful heart.



CHAPTER XI.

OUT OF THE FRYING PAN INTO THE FIRE.

Frank took the first watch.

It was to begin about ten o'clock that night; for both of them had remained on deck, talking, up to that hour. The night was so comfortable after the hot day that they disliked going into the sleeping quarters. These happened to face the deck, however, so that the vessel was admirably suited to cruising in tropical regions.

"Every thing seems to be going on decently right now," remarked Andy, yawning, as he prepared to have a few hours' sleep.

"That's so," returned his chum. "But while we've got some of the faithful ones on duty, we mustn't forget that there may be other snakes aboard. Enrique and the little shouter may not have been all the sympathizers with the revolutionists. And not for a minute will we relax our vigilance."

That was Frank's way; and just now Andy fully approved of it. His heart was so set upon having a chance to use the monoplane in the endeavor to discover that strange cliff-enclosed valley, where his father was imprisoned, that he did not mean to take any chances of losing out through over confidence.

So he packed off to his berth, while Frank prepared for three hours of lonely vigil. He expected to make the rounds just about once in so often, and have a few words with the man at the wheel. Felipe had declared that it was his intention to keep busy himself through the night, since he dared not trust the wheel in the hands of an inexperienced pilot while darkness lasted.

In the morning he could give directions, and allow an assistant to do the work, while he secured some rest.

There was no moon after early in the evening, when the young queen of the night disappeared in the west, leaving the bright stars to control the skies.

The boat continued to make good headway against the current, though at this season of the year the Magdalena is bank full with the summer rains, which fall almost every afternoon in a deluge.

A searchlight sent a dazzling shaft of light far ahead on the troubled surface of the booming flood. This was an absolute necessity, for otherwise it would have been too dangerous bucking against that tide; laden as the river was with floating tree trunks of gigantic size, that had been swept from their resting-places in the lowlands above.

Once Frank had seen a wild animal crouched on one of these great logs. The boat passed so very close to the floating refuge of the beast that ere darkness claimed the strange craft with its stranger cargo, Frank had been able to see the tawny hide of the crouching beast, and note the quick, jerky motion of its long tail.

Upon hurrying to the pilot house and making inquiries of Felipe he learned that, just as he suspected, the animal was a jaguar, the most feared inhabitant of the tropical forests away off at the headwaters of the Magdalena and Orinoco rivers.

There was a spice of peril hovering over the progress of the little boat during every hour of that night. It might come in the sudden leap of a wild animal, that judged any port would be better than a floating log. Then there was a chance of their running afoul of a monster derelict, in the shape of a drifting snag, that might punch a hole in their bow, and bring about trouble.

On top of all was this unseen peril from the revolutionists, who were making the Magdalena country the center of their renewed activity, for some reason or other, and had their minds set on securing the first aeroplane ever known to be in Colombia.

The time passed away. When three hours had really gone, and all seemed well, Frank awoke his chum. Generous to a fault, he might have held out much longer, for he did not feel exhausted; but Andy, who knew him like a book, had made him promise faithfully, on his word of honor, that he would arouse him at exactly the time agreed upon.

"Everything lovely, and the goose hangs high!" Frank said, as the other joined him presently on deck.

"That's good," replied Andy. "And as it is now one o'clock, with no trouble doing, looks good to me that we'll pull through the night without a mess."

"You never can tell," observed the careful Frank. "And the only way to do is to act just as if you felt positive something was bound to crop up."

"I know it," came the reply, as Andy started to walk up and down a bit, so as to get the last remnant of drowsiness out of his system.

For an hour he found little trouble in keeping awake. He made frequent trips to where Felipe stood at his wheel, his keen eyes keeping constant vigil ahead, in order that he might steer clear of such snags as threatened to stove a hole in the hull of the steam yacht.

Now and then Andy could see one of the crew moving about; but as some of them must have duties to perform, even in the night, he did not look upon this as a suspicious circumstance. Only, he made sure that no one wandered in the near vicinity of the locked lazerette, where the precious monoplane lay, securely crated.

In some places the river proved much narrower than in others. And, of course, it was here they had their greatest trouble. The current was increased, for one thing. Then the floating objects swept forward with more speed, so that it required additional dexterity in order to avoid them.

But old Felipe knew his business well. Andy believed they had made no mistake in leaving matters fully in his hands.

It was about the end of his second hour that the pilot volunteered some information that gave Andy more or less uneasiness.

"Just ahead, young senor," he said, when for the fifth time the boy entered his deck pilot house, "we come to the narrowest place in the whole river at this section. And there, if anywhere, I expect that they will be waiting for us."

"Do you mean the revolutionists?" exclaimed Andy, interested instantly.

"No other, senor. If we manage to get past there, all will be well. But they may be encamped on both shores, and demand that we draw in under penalty of being fired on," Felipe went on, without removing his snapping black eyes for even a single second from the ever-moving panorama of shifting water and floating debris, that the searchlight disclosed ahead of the laboring boat.

"But nothing must tempt us to obey; no matter if they send volleys aboard. The distance is too far for them to do much damage; and I hear they are as a rule pretty punk shooters."

Felipe may hardly have known what that word meant, but he could give a guess.

"But sometimes, young senor, they even have cannon!" he remarked.

"You don't say!" ejaculated Andy, in new alarm; but he quickly caught himself, and went on. "Let 'em try it then. We'll just shut off the searchlight, and take our chances for a while with the old floaters on the river. Then perhaps they won't see anything to bang away at. Anyhow, just make up your mind, Felipe, we don't haul in, not while the blessed old tub keeps above water."

"It is good to hear such brave talk," said the old pilot, chuckling. "Me, I will keep going straight ahead, no matter what comes, until I have the order from you to turn the boat. Yes, let them shoot, senor. After all, I do not believe they could hit the side of a palace in this dark."

All the same Andy thought he ought to arouse his cousin, and make Frank aware of the new threatening peril.

On hearing the facts, Frank agreed with all the one on guard said, even to being ready to extinguish the useful searchlight when the critical moment arrived.

"We'll just have to take chances, that's all," he declared. "Even if we came swat up against one of those floaters, that's no reason we'd be snagged and sunk. They make these boats pretty strong, over there across the big pond, and I guess our hull could stand a hard punch."

"Yes," remarked Andy, feeling easier, now that Frank was on deck, ready to take matters in his able hands; "and after all, it's a choice between two bad things, in which we pick out the lesser. Hang the old insurrectoes, I say! Why can't they just pay attention to their own business, and let us two peaceful Bird boys alone?"

"Well," laughed his chum, "you know how it is yourself, when you want something pretty hard. And they've got the notion in their stubborn heads that if they only had a modern, up-to-date aeroplane, they could just make the miserly old government come to terms instanter. Don't blame them too much, Andy. Maybe you and I would do the same thing—if we were Colombians, and on the outs."

"Looks to me like there was something like a fire ahead, Frank!" declared Andy, right at that juncture.

"I say, you're on the spot every time, old fellow," observed the other, as he shaded his eyes to look. "There's a sharp turn ahead, where Felipe says we enter the narrow place. And I honestly believe they've got a bonfire burning on the right-hand bank."

"Then, after all, shutting off our bully little searchlight won't do us much good," complained Andy, regretfully.

"Don't you believe it," Frank hastened to remark. "A fire isn't going to reach all the way across the river, which is pretty wide, even at its narrowest part. And depend on it, our clever old wheelsman will keep just as snug up against the left hand shore as he dares go."

All the same, despite these assurances from his cheerful chum, Andy confessed to a secret feeling of apprehension as they drew closer to the point of land beyond which the danger possibly lay in wait.

It seemed to him that every conceivable species of peril threatened the sacred enterprise, upon which he had so eagerly embarked. From various sources did harm hover over their heads. And even though they passed safely through all these, there must be many more to come, after they had launched their little airship, and started to explore the strange regions of this tropical land.

"It's a fire, all right, Frank," he said, as they negotiated the bend, and opened up a new vista ahead.

"Yes, that's so for a fact," returned his chum. "And notice, will you, Andy, how old Felipe has managed to keep over well toward the port shore. He sized up the situation all right, and knew how to act."

"Yes, Felipe tells me he used to serve in the army. Many a battle he has been through, not only in Colombia, but in other countries as well. He was once something of a soldier of fortune. But where are you going, Frank?" as his comrade started to leave him.

"I must warn the crew to keep out of sight, or they may be hit, if there happens to be any shooting going on," called the other, over his shoulder.

He found that every member of the crew seemed to be awake, as if they had talked the situation over, and also guessed where the trouble would lie in wait for the venturesome young Americano senors.

So Frank gave his warning, and saw that they obeyed. While they were in his employ he felt a certain degree of interest in these ragged fellows, and did not wish to be held responsible for any damage they might receive, if inclined to be reckless at times.

When he once more reached Andy's side the latter was looking through a pair of marine glasses they had fetched along, thinking they would prove especially valuable in scrutinizing the country over which they might be passing in the aeroplane.

"They're our friends, the revolutionists, I reckon," he announced. "I can see several who carry big swords that dangle around their heels. And the common soldiers, while they have little if any uniforms, and some of them no shoes, seem to all have guns in their hands. Here, look and tell me what that is on the little rise. I'm afraid our worst fears are going to come true."

"Well, you're right, Andy," replied the other, after he had clapped the binoculars to his eyes. "That's a cannon, all the same, and they're getting ready to shoot!"

"Oh! my! It makes a fellow's flesh just creep, to think of being banged away at with a great big cannon!" declared Andy.

"This one isn't so very big, I think. And now we're nearly opposite where the fire burns. They're going to make a move to show their hand. Drop down flat on the deck, Andy—quick with you!" and Frank, as he spoke, set the example himself.

Hardly had the two boys thus thrown themselves down than there was a heavy boom, accompanied by a brilliant flash of fire from the shore.

The revolutionists had fired upon the little steam yacht!



CHAPTER XII.

A GREAT SURPRISE.

"Wow! now, what do you think of that?" exclaimed Andy, raising his head, just as one of the big turtles native to these warm waters might thrust his out of his shell.

"Why, that was only a warning to bring us up short, and pay attention!" declared Frank. "Because, as you saw, the ball splashed the water ahead of our bow."

"But Frank, we don't mean to head across?" cried Andy, getting up on his knees, the better to see.

"To be sure we don't. That was all settled long ago; and you notice that our good Felipe is still keeping her nose headed straight upstream. Now out goes the searchlight, just as we arranged. Wonder what they'll think that means!"

"Perhaps they'll believe they knocked it overboard with that shot!" suggested Andy, who could joke, even when facing troubles as thick as a sea fog.

"Listen!" Frank exclaimed, "there's a chap with a pair of leather lungs, shouting a lot of gibberish. I suppose he's demanding our surrender, and threatening to blow us to smithereens if we decline to believe him."

"One good thing is that each minute takes us further up the river, and every foot counts in this game of runaway. Already we're past where the gun stands; and those fellows are working like fun to get her turned around, so as to point after us. While they load we're doing more stunts. Yes, and Frank, we're leaving 'em in the lurch, I do believe."

"Sure thing," returned Frank, composedly, "only both of us want to duck when it looks time for the blamed old gun to bang again. They mean business from the word go, now, and will shoot to hit! By some accident it might run afoul of the boat, and splinters fly. There, get ready to drop, Andy! It's coming!"

It certainly was, for immediately another flash sprang up, accompanied by the same deep bellow, as the fieldpiece was discharged. No doubt, while it may have been rather out of date in pattern, the cannon was good enough to have done savage execution, handled by expert German or French gunners.

But there did not seem to be any such among the rag-and-bobtail army of the new aspirant for the presidency of Colombia. At any rate, the missile whizzed and whined past the retreating boat, missing her by yards.

"Bully!" shouted Andy, jumping up and cutting a few pigeon wings on the deck to illustrate just how pleased he was. "By the time they're ready to let her off again we'll be nearly out of range. And from the looks of the bank I feel pretty sure they never can catch up with us, toting their old gun along."

Three minutes later there came the third report, and they heard the ball pass high overhead, proving that the marksmen had entirely lost all traces of the boat and simply fired at random.

"That settles it," said Frank, decisively.

"Do you think so?" asked his chum, joyously.

"No question about it, Andy. Like the government official on the wharf at Barranquila, they realize that the game didn't work, and if they want to get us they'll have to lay some new plans when we come back again. But we're not bothering our heads about that, you know."

"Never even cut a chip off our boat!" declared Andy.

"Well, I'm going back and get the rest of my nap. Wake me up at four, remember. I want the last watch," and Frank dove within his stateroom with as much seeming indifference as though this thing of being fired upon with fieldpieces might be an everyday occurrence in his experience.

Morning dawned upon the Magdalena. Frank was on duty at the time and drank in the lovely picture. Birds flew overhead, cranes arose from along the shallows in near the shore, where they had been fishing for their breakfast, and there were many strange feathered creatures to be seen, such as the boy had never up to now set eyes upon.

Some of the crew were trailing fish lines astern and every now and then a prize would be hauled aboard, which later on might afford a meal for passengers and workers.

Andy soon made his appearance, the rising sun having sent a few slant rays into his sleeping quarters and aroused him by falling on his face.

"This is something like, eh, Frank?" he remarked, as he drew in a big breath of the bracing morning air.

"I should remark, yes," was the other's reply.

"We've apparently left all our dangers behind," Andy ventured. "That is, I mean there's little likelihood of our being robbed of our precious machine now, with both government officials and envious revolutionists left in the lurch."

"I was just asking Felipe and he says we shall have another day and night of bucking up against this nasty current. You see, Andy, it's on an unusually big bender right now, which makes it doubly hard to fight it."

"Oh, well, what can't be cured must be endured, I guess. So I'll try to take it as easy as I may and be thankful it's no worse," Andy replied.

The morning passed without any event worth mentioning. And all the while they kept steadily at the business of eating up some of the two hundred miles that Felipe assured them lay between Magangue and the city at the mouth of the big river.

Another thing was worrying Andy, however. He finally broached the subject to his comrade knowing that in this way he would get relief.

"That blessed old engine has been doing bully for a long time now, Frank, but judging from past experiences, she's due for another sulky fit soon. Whatever would we do if she let down all of a sudden, while we were right in the worst kind of a swift current? My! we'd be carried miles downstream before we could do anything."

"Oh, no we wouldn't!" remarked the other, smiling.

"Then you've been thinking it all over and made ready to offset a balk, I bet anything," declared Andy, with vehemence.

"Do you see that anchor forward?" asked Frank, pointing from where they stood on the raised deck aft. "Well, that's got a good long stout chain attached and is placed where a kick will send it over. Notice old Quita squatting close by? Think he's taking a snooze, he seems so quiet? But all the time the old chap's on the alert, and he has his orders, too."

"To upset the anchor over the bow, you mean?" asked Andy.

"Just that," came Frank's reply. "If anything happens to the machinery you'll hear a series of quick whistles from Felipe. The boat won't even have a chance to lose headway before over plumps the big mudhook, and we'll just take a rest out in the river until repairs can be made again by Engineer McClintock and his assistants."

Andy looked at his chum admiringly.

"Blessed if you don't just think of everything!" he said; "and get ready long before it happens. However do you do it, Frank?"

"Oh, it's easy, once you make up your mind," laughed the other. "I took to it long before this new Boy Scout movement started. You know they've got as their leading motto the words: 'Be prepared.' And there never was a better slogan ever given to boys. Think how many things might be avoided if we were always prepared."

"Yes, I've given the subject much thought," grumbled Andy; "but somehow I seem to slip up when it comes to the critical time. I stay awake eleven hours, and just when I doze off in the twelfth watch the blamed thing happens! It's always that way, seems to me. How can a fellow stay awake all the time, tell me that?"

"Oh, rats! There's no need of that. Just fix things so you'll be aroused when it comes along, and be ready to turn the tables."

So they talked away into the afternoon. The engine seemed to be on its best behavior. McClintock, the Scotch engineer, who was the only foreigner aboard besides the boys, reported that he was beginning to have more faith in the machinery. The work of the last twenty odd hours had certainly been a pretty heavy tax on it and everything seemed to be going like clockwork.

"I only hope it'll keep up, then," said Andy. "One more night is all I ask. Then Felipe promises to have us at our journey's end, when I can see and talk to the very man who picked up that wonderful little parachute, with its message from the unknown valley among the cliffs. I wish the time was here right now."

"Felipe, by the way, is taking his rest now," said Frank, after a little time; "for he expects another night on duty. We still meet many tree trunks sweeping down on the current. The man at the wheel has to keep on guard constantly. Look at that tremendous one, will you, Andy? And just notice how dense the forest is ashore around here. How any one can get around at all beats me. I should think they'd have to keep their machetes busy all the time cutting the matted vines away."

"I understand they do," the other went on. "And I rather guess that there's hardly a country under the sun where an aeroplane would be of more real benefit than right here in the tropics. Think of avoiding all that tangle—of floating along, a mile a minute if you wanted, far above the tree tops and away from all such a muss."

"You're right," agreed Frank, fervently. "And it's the only way any one could ever hope to discover this strange prison of your father. From a distance of a thousand feet we can have a big range of vision. With our good glass it will not be hard to discover the cliffs, if only we figure out in which direction we can have the best chance. And I think I've got a scheme ready to manage that."

"I depend on you to do it," said Andy. "Alone by myself I would simply despair of ever learning anything worth while. But while you are along I just feel that we're going to succeed."

"I ought to thank you for saying that, but I won't," Frank declared. "Because it makes me tremble for my reputation as a prophet."

"But you have seen nothing to make you less confident, I hope?" cried the other.

"To be sure I haven't," replied Frank, readily enough. "On the other hand, I ought to feel better satisfied than ever, because we've managed to outwit every cause for trouble that has cropped up this far. We'll get through this coming night without accident, because we're ready for anything. Then, when another day dawns, we'll haul in at Magangua, to hunt Jose Mendoza up and hear what he can tell us about the parachute that fell among his cocoa trees."

"Hark! what ails the men forward?" exclaimed Andy just then.

They sprang to their feet and rushed to where they could see what was going on.

"Perhaps a mutiny!" exclaimed Frank, who could not tell what queer thing was ever going to happen down in this land, the people of which were so different from all whom he had ever known before.

Andy uttered a low cry of alarm and began to fumble for the revolver Colonel Josiah had made him promise to always carry on his person, once they reached the country of revolutions.

The first sight they obtained told them that something unusual had indeed happened. A number of the native crew were in range of their vision, but every man had fallen flat on his face and seemed to be cowering there as if afraid.

"What in the dickens is it?" gasped Andy.

"I don't know. They are a scared lot, that's sure! Perhaps they saw a sea serpent alongside! It couldn't be that a jaguar has boarded us. No, look at old Quito, how he lifts his head and takes a terrified look! Why, he seems to be observing something up above in the heavens as sure as you live!"

As Frank shot out these words he, too, bent his head back to scan the brazen sky above. A cry broke from his lips.

"Why, what under the sun does it mean?" exclaimed Andy, who had also turned his eyes heavenward to discover a strange thing speeding over the tops of the trees, one, two thousand feet high, and at the same time there came to his ears a familiar throbbing that could have but one meaning.

"An aeroplane!" he burst forth in thrilling tones; "and the sillies down there think it's just a frightfully big bird about to carry them off. Hey, Frank, perhaps the government has got one of the new contraptions after all!"

"Go slow," said Frank. "Suppose you look a bit closer, my boy. Isn't there something familiar about that same craft up yonder?"

"It's—it's a biplane, Frank!" gurgled Andy.

"Yes, and one you've set eyes on before, too, old fellow. It belongs to—"

"Puss Carberry!" burst from Andy's quivering lips, as he continued to stare, as if almost unable to believe his own eyes.



CHAPTER XIII.

THE "DEVIL-BIRD."

"Yes, Puss Carberry and his crony, Sandy Hollingshead!" declared Frank, positively.

"But, it seems impossible! All these hundreds and hundreds of miles away from old Bloomsbury and Puss Carberry floating over us! Sure I must be dreaming, Frank!" stammered the other, still gaping up at the rapidly passing aircraft.

"No, you're just as wideawake as ever you were in all your sweet life," said Frank. "Take a better look, Andy; don't you see now that it's the same biplane we raced with the day Sandy dropped that bag of sand, hoping to break our winning streak in the dash for Old Thunder Top?"

"Anyhow it's a ringer for it, I give you my word!" muttered the stunned boy.

Frank, with an exclamation of impatience, sprang forward and snatched something up that had just caught his attention. This proved to be the fine field glasses that had been brought along on the adventure.

These he clapped to his eye, and as they were already fitted and adapted to his sight, he lost not a second in covering the passing aeroplane.

"Look for yourself, my boy!" he cried, handing the binoculars over to Andy, who hastily raised them.

"Well, I declare, that settles it!" ejaculated that individual immediately.

"You recognize them, then?" asked Frank.

"It's Puss as sure as thunder. I can see him plain. The other is just out of line, but there's something about his figure that makes me ready to say it's our old friend, Sandy," Andy replied, amazement still gripping him tightly.

"Well," Frank observed, "after all, the only queer thing about it is our glimpsing them so soon. We knew they were headed down this way somewhere, but they made quicker time than our best. And just to think that they're the first to fly an aeroplane along the region of the Magdalena."

"Huh! they beat us up in the air that other time, yet when it came to a showdown, we left 'em at the stake!"

Andy was beginning to recover his breath, and with it came renewed confidence.

"Do you see anything in the actions of Puss that would indicate he had recognized us aboard this boat?" asked Frank, for the other still kept the glasses glued to his eyes.

"No, I don't," replied Andy, presently. "You see they're awful high right now, and without glasses they could never make us out down here."

"I guess you're right," was Frank's decision. "Perhaps it's just as well, for there's never any telling what mean trick those fellows have got up their sleeve."

Andy suddenly removed the glasses and a sudden pallor seemed to cross his face.

"Oh, Frank!" he cried, "you don't believe they'd ever be so wicked as to try and stop us from searching for my father, do you? Bad as Puss Carberry is, I can't just believe he'd ever do that."

"Well, I hope not," returned the other, but there was a trifling vein of doubt in his voice, for he had long ago ceased trying to figure to what depth of depravity those two schemers might descend.

"But where do you suppose they came from right now, Frank?"

"That would be hard to tell," Frank replied. "The first you saw of them they were sailing up over yonder. Then the chances are they have quartered themselves at some town, perhaps on the river, and that this is just their first flight—a sort of look over the country."

"Yes," said Andy, "they're circling right now as though they mean to head back again."

"Well, you can't blame them much," Frank ventured, watching the actions of the aviators above with keenest interest. "Night isn't so very far away, and I should think a fellow would hardly feel like being caught out after dark down here in an airship."

"Well, hardly," Andy smiled. "Curfew must ring for us every time. Fancy dropping plump in the middle of such a jumble of forest as that is yonder, and I bet you it's just cram full of snakes, jaguars and everything else that would want to snuggle up to a poor birdboy dropped out of the clouds. Me for daylight when I go sailing down in this blessed region."

"Look, the men are beginning to recover from their fright," remarked Frank in low tones. "There's old Quito sitting up now and commencing his everlasting jabbering with the others. See him point to the biplane and then to us, Andy."

"Say, the sharp old coon is getting a pointer on us. He's telling his chums right now that the thing we've got stored away in the lazerette is just such a big bird as that going away over yonder. Am I right, Frank?"

"You never said a truer thing. But they were certainly a badly rattled crowd for a time. And we can hardly blame the poor fellows, for what could they think but that it was a tremendous bird of prey, looking them over with an eye to grub?"

Frank laughed a little as though the recollection of the fright of the crew would always seem more or less ludicrous.

They sat there and watched until the mysterious biplane had completely disappeared in the hazy distance that marked the coming of evening.

"You don't think then," asked Andy, when it had vanished from view, "that Puss and his biplane could have fallen into the hands of the Colombia authorities and that they're using it for scouting to learn the movements of these ragged revolutionists?"

"No, I don't," was Frank's quick response. "You said you could positively make out Puss at the wheel, and I'm almost sure it was Sandy with him. They must have slipped into the country without giving their secret away. Trust sly Puss for knowing how to do that sort of thing. He never goes around with a brass band, telling what big things he has on tap."

"That's right. Why, just think, not a soul knew about his old biplane until he had it about done. We were working in the open almost, telling much of our plans, but Puss pretended to be mighty envious and asked questions, when all the time he was meaning to beat us out. Of course, he could get into Colombia without giving his secret away. You don't need to tell me, Frank, you're surprised at that."

"No more I am. But there goes the sun. How quick it seems to drop out of sight down here," Frank remarked.

"Sure," laughed his cousin, "but all the same I fail to hear any bang. You remember the Irish immigrant who heard the sunset gun at a military post in America for the first time and on being told that it denoted sunset, innocently exclaimed, 'Sure, the sun niver goes down in Ould Ireland wid a bang like thot!" But already the dusk is creeping out of the dense woods on to the river. And I'm getting hungry. It must be near supper time. I wonder what the folks up home are doing right now?"

"Just what we are, likely—waiting to hear a welcome sound that will call them in to feed. And there comes little Pepito to blow the conch shell that he uses for a dinner bell. Come, Andy, get a move on you. Another night and then we are going to do business at the old stand. It will be just fine to soar above this strange country and see for miles and miles—mountains, valleys, rivers, tropical forests, and everything that we've never looked down on before."

The two young aviators went into the cabin for supper. They fared very well insofar as food was concerned. Of course, both of them missed the home cookery. The native who attended to this part of the program did his level best to please, and he certainly had plenty to work with. But his Spanish style of serving even the most ordinary dishes of tinned meats with a dash of garlic was beginning to pall upon the taste of the American lads.

Frank had even started to show him other ways of cooking, and they had hopes of converting the cook by slow degrees.

The night was in one sense a repetition of the preceding one. True, they would not have to consider being halted by a gathering army of the revolutionists, and that was a comfort all around. At the same time Frank deemed it necessary that he and his cousin keep watch. And Andy was perfectly willing to sacrifice some of his personal comfort for the sake of insuring the safety of the precious aeroplane.

It proved just as well that they had so determined. During Frank's second term on guard and somewhere around four o'clock, while darkness covered the land, he thought he caught a glimpse of a shadow crossing the deck, headed in the direction of the lazerette.

He had been lazily reclining on a soft cushion made of several blankets and looking up at the silvery stars, but immediately he became fully aroused. This might mean danger in some shape toward the aeroplane. And no matter, it behooved him to investigate.

So he softly arose to his knees and crept after the shadowy figure.

Cautiously he approached the place where the door belonging to the storeroom was to be found. As he advanced thus he could occasionally catch a peculiar clicking sound, which he believed must be made by some one trying to pick the lock!

The engine of the boat kept up considerable of a racket as it steadily worked along without the dreaded hitch. Besides, there was always more or less splashing of water against the sides, as they pushed against the swift current of the Magdalena. All these things combined to muffle the clicking sound frequently, yet during little lulls Frank could catch it again.

The tumult also served to deaden any shuffling he may have made while creeping toward the lazerette door, and for this Frank was thankful.

It was very gloomy here. A hanging lantern some distance away only served to accentuate the gloom apparently. Still, by straining his eyes, Frank believed he could just manage to make out a stooping figure at the door. Yes, he was certain that it had just moved, and now the peculiar clicking was much plainer.

When it stopped he remained perfectly motionless, nor did he again commence his creeping forward progress until it started once more.

Frank no longer had the slightest doubt concerning the cause of that suspicious clicking. One of the crew was endeavoring to force an entrance into the locked lazerette, doubtless with the intention of destroying the valuable aeroplane. He might be in league with the revolutionists and in this way hoped to prevent the government from eventually securing possession of the machine which would put the insurrectos out of the running.

But Frank had conceived another idea. He now believed that his fellow might have been sent by the crew to destroy the "devil-bird," as they undoubtedly considered a contraption that could soar through space as fast as the fleetest condor.

No matter. It was his business to put a sudden stop to the action. And while doing so he must not be too rough in his dealing with the fellow, lest the entire crew rise in revolt.

When he had reached a point that allowed of a leap, Frank suddenly sprang forward. He did not know just what he might be up against and had even taken from his pocket the splendid new pistol which Colonel Josiah, himself a world traveler, had insisted upon giving each of his boys before they started on their trip south.

"Surrender!" cried Frank, believing that the very sound of his voice would do much toward frightening the would-be traitor.

But he hardly expected such a tremendous upheaval as followed. The man, believing that possibly the "devil-bird" had broken out of its cage and was about to carry him off in its gigantic beak, gave a shrill scream of terror, and bouncing up, broke the slender hold Frank had secured upon his person.

Not to be outdone, Frank, recovering, chased after him. He believed it his duty to at least learn the identity of the rogue, so that he might understand just how deeply the conspiracy had taken root in the crew.

Between himself and the hanging lantern he could make out the fleeing figure of the fellow, and hot in pursuit he followed as fast as his feet would let him. The man undoubtedly heard him coming, for, if anything, his fright increased. Out upon the open deck they flew, Frank just a few feet in the rear. He had even stretched out his arm and touched the garments of the runner, when with a screech the fellow made a furious plunge straight over the side of the boat.

He evidently chose to take chances in the swift current of the Magdalena rather than trust himself in the power of the unknown pursuer, which doubtless he believed to be the dreaded "devil-bird" that had been confined in the box cage!



CHAPTER XIV.

THE AIRSHIP LAUNCHED AT LAST.

Frank came near following after the unknown member of the crew, when the other made that flying leap over the side of the boat. Not that he wanted to take a bath just then, but his forward progress had been rapid, and he only saved himself by banging up against the taffrail, which was unusually high for so small a vessel, and holding on sturdily.

He had heard the splash as the fellow reached the water. Doubtless he was a good swimmer, as about all these natives seemed to be, and barring his falling a prey to some loitering alligator or other reptile, he would be able to gain the neighboring shore further down.

At any rate it was folly to think of looking for him.

"What's all the row?" cried Andy, as he came plunging forth from his stateroom.

Some of the crew were even then looking over the side, and Frank imagined they could give a pretty good guess as to what it meant. But he heard not a word from even old Quito, and while the absence of a man must be noticed in the morning, there would probably be no complaint.

When Andy heard about the attempt to injure the monoplane he was in a tremble.

"Did you ever?" he exclaimed. "Why, it seems as though everything just wants to knock us. When we give the government officials the merry ha! ha! and even slip past the revolutionary army, after being bombarded by their old cannon, here even our own men want to smash our precious aeroplane, under the belief that it's an evil bird, come to bring bad luck to the people."

"Better go back to your bunk and forget it," remarked Frank, who was tenderly rubbing his elbow where it had come in contact with the hard taffrail at the time he stopped so suddenly, balking at a bath.

"Me? Not on your life, Frank!" declared Andy, with much emphasis. "I'm going to take a blanket and just lie down in front of that blessed door. Nobody can get in then without walking over my body. And if I catch a fellow trying it on, believe me, I'll give him something he won't forget in a hurry. It'll be touch and go with him, I bet you."

Which he actually did, much to Frank's secret amusement, camping out there on the floor as close to the locked door as he could get, and bracing his back up against the same.

But then, fortunately, morning was not so far away and Andy would have only a couple of hours, more or less, of his self-imposed labor.

They knew that if the pilot of the river expedition said truly, they must even now be drawing near the town of Magangue. Possibly it would break upon their vision with the coming of dawn.

Frank himself had no more intention of retiring to his bed than had Andy, but continued to keep watch and ward until he saw the first peep of daylight over the port side of the vessel.

Then he communicated the glad intelligence to his chum, and together they stood there, watching the slow unfolding of dawn. From an ashen gray the sky began to be marked with brighter hues; pink flushes traveled along in lines that centered in the spot where the sun would presently appear, and the gloom of night retreated once more back to its hiding places among the mountain passes.

"There's the dinky old town!" cried Andy, pointing with trembling finger.

"It is and no mistake," replied Frank, himself experiencing a sensation of considerable relief, for at times it had seemed more than doubtful whether the little expedition could ever overcome the many difficulties that beset its passage up the swollen river.

And so they came to land just as the glorious sun showed his smiling face. Andy declared that this was a harbinger of good luck, and his cousin chose to readily agree with all he said, for it pleased him to see Andy look more like his old self than he had been for many a day.

"Remember, only one of us ashore at a time until we land this cargo," remarked Frank, as they came to bring the boat to the bank, where a group of natives waited to see what it all meant, surprise written largely on their dark faces.

"That's right," responded the other traveler. "But I'm going to have the aeroplane carried out on deck at once, so it can be taken ashore as soon as we find where we are at. What we want first of all is to hear about our friend, Carlos Mendoza, the cocoa planter. Perhaps he lives miles away and we'll have to get some sort of conveyance to tote our machine out to his place."

"Yes," observed Frank, "I've been laying out plans along that line. If you don't mind I'll drop ashore while you're having the crates brought on deck and make inquiries. Even away down here in this wilderness money talks. Colonel Josiah told us it did for him in the heart of darkest Africa, you know. And a few bolivars will hire all the help we want."

Andy was perfectly agreeable that his companion should have taken upon himself the task of engineering things.

"You can always discount me when it comes to bargaining," he said, laughingly; "so go ahead and fix things to suit yourself, Frank."

Upon reaching shore, Frank, who had taken old Felipe along with him to serve as interpreter, found that Carlos Mendoza had his home just on the border of the town, though it was a little distance away. He soon made arrangements for hiring a native cart to be used in transporting the precious aeroplane.

In less than half an hour they were on the way. The boat had been left in charge of McClintock, the Scotch engineer, who would make sure that the crew remained on board or lost the wages coming to them.

Both of the boys were so excited that they paid little attention to the strange scenes which now surrounded them in the valley town far back in the interior of tropical Colombia. Indeed, one might even have suspected that they had always been accustomed to living in a region where all manner of tropical fruits abounded, coffee and cocoa were raised as crops, and birds of brilliant plumage flew overhead.

The truth of the matter was, they knew they would presently come face to face with the planter who had actually picked up the little messenger sent out of his cliff bordered prison by Professor Bird. And this fact set their nerves to trembling with eager anticipations.

In due time the cart on which the aeroplane had been secured, together with the luggage which the young aviators wished to carry along, drew up before a long, low white building, back of which could be seen orange trees and other evidences of a real tropical home.

Their coming must have been noted, for a gentleman was advancing from the grove at the rear. Senor Carlos looked surprised at seeing the caravan bringing up before his door, but that was as nothing in comparison with his amazement upon learning how one of the two young Americanos was the same Andrew Bird to whom he had desired his friend, Senor Almirez, to forward the strange message picked up in his cocoa grove one day several months back.

The boys had learned from Senor Jose that the owner of the plantation could understand English and even speak it fairly well. Thus they had no need of fetching Felipe along to act as interpreter.

"Oh, please first of all let me see the remains of the silk parachute that was attached to the bark letter!" said Andy, after they had conversed for a short time and some of the planter's hired servants had unloaded the boxed aeroplane, which was stowed away in a place of security.

Doubtless the planter understood the reason for the boy's solicitude. He immediately took them inside the house and in another minute had thrust into Andy's eager hands a discolored piece of silk, such as is used in the making of balloons.

Nor did either Frank or the Colombian planter think it strange that the boy should press the token again and again to his lips, while tears ran down his face. They could understand the feelings that filled his heart, and no matter what the nationality may be, the honest love of a lad for his father cannot but provoke admiration and respect.

"And now," said Frank, presently, when his cousin had in a measure recovered from his first emotion, "will you tell us, Senor Mendoza, just how you found this strange communication? I hope you remember the exact day, because it is of the greatest importance to us that we learn, as near as possible, from just what quarter it came."

"Si, senor, I understand that," replied the planter, eagerly, his dark face aglow with enthusiasm. "I made note of the day in my diary, also the fact that it was the third day in succession when the wind blew direct from the south, with just a faint turn to the west."

"Splendid!" cried Frank, turning to give his chum a reassuring nod. "What did I tell you, Andy? The forethought of Senor Carlos has made our task much easier. There can be little doubt, then, that the hot air balloon must have started in a region that lies almost due south of here, possibly with a slant, as he says, toward the south by west quarter, as a sailor would call it. And now, senor, can you tell us just where a direct line that way would bring us?"

"First over the lowland and the forests. Then, if you go far enough amigos, it is the Sierra San Jeronimo mountains you would strike," replied the planter.

"Yes, I remember them on the map we have, and that corresponds exactly with all I had in my mind," Frank observed, his forehead wrinkled with serious thought.

"What sort of country is it up in those mountains?" asked Andy.

The planter shrugged his shoulders.

"That I am unable to tell you, amigos, since I have never been there. From all I have heard I believe it is one of the wildest and most inaccessible regions in all our country. Lofty peaks warn back the most daring explorer. Few have ever ventured to attempt to go among them. Some never came back, they say. The superstitious declare those mountains are filled with evil things. Nothing on earth could tempt one of my peons to accompany an expedition thither."

"Then it is lucky that we will not need any assistance in our adventure," remarked Frank. "With an aeroplane one may be independent of help. And now, Andy, what shall we do? It will take us the better part of the day to assemble our little flier and get things ready for an ascent."

"That means another horrible night of waiting before we can make a start," said Andy, looking quite forlorn.

But he soon understood that it could not be helped. Both boys were presently hard at work, with the deeply interested planter watching every move. All the while they conversed and the subject of pretty much all their talk had more or less to do with the country, the peculiarities of climate, what sort of weather they might expect to have and dozens of similar matters.

Doubtless Senor Mendoza would like to hear of things connected with the great outside world, which he seldom saw anything of, but he realized that these would keep until after the brave young senors had completed their task of humanity.

Before evening came they had everything arranged to suit the critical Frank. Both boys were pleased to find that the monoplane had come through its long journey without any damage having been done.

That night they were uneasy about the precious airship, and at their request the planter had their beds made up in the shed where the "Bug" lay. But there was no attempt made to injure it in the least.

Then came the morning. Andy could hardly eat a bite of breakfast, for the eagerness that possessed his soul. Every servant on the plantation had gathered to look with awe upon the wonderful bird-like machine, on which, it was whispered, these two venturesome young Americanos meant to soar among the clouds.

Finally the last word was spoken, the planter shook hands with each of his visitors, Frank turned on the power, the aeroplane with the motor exhaust sounding like a volley of musketry started to run along the level ground, and presently, to the consternation of the entire gathering, began to climb upward, just like a creature of magic!

Cries of awe arose from scores of throats and to a man the peons threw themselves flat on their faces, hardly daring to look at the terrifying spectacle.



CHAPTER XV.

AN UNPLEASANT SURPRISE.

"At last, Frank, we're on the move!"

"Yes," replied the one at the wheel, as the cries and cheers from below were drowned by the volleying motor explosions; "and did you see the senor kissing his hand after us, while his men were flat on their faces?"

"It was a queer sight," Andy remarked. "And no wonder these ignorant peons call our little monoplane a 'devil-bird.'"

"Look down now. Just to think of two Yankee boys being allowed to swing over a tropical scene like that," said Frank.

Both of them were deeply interested. In the valley they could see the little town, with the river stretching off toward the south. Then there were the patches of tropical vegetation, the fruit trees and the cocoa plantations—all those interesting things which neither of them had ever set eyes on before.

Senor Mendoza had told them how the coffee was grown upon a certain part of the mountain slopes, since it did not do well in the valleys, preferring a higher altitude.

They followed the course of the river generally, intending to cover possibly something like eighty or ninety miles before trying to comb the land from side to side, in the endeavor to find the strange cliff enclosed valley.

From time to time Andy would call the attention of his aeroplane chum to some striking feature of the landscape far below. The little Kinkaid motor was humming merrily, without ever missing a stroke, and Frank, having the utmost confidence in its steadiness now, after so many trial spins, could take a few seconds at a time to observe these things.

"When we've gone something close on an hundred miles direct," remarked the pilot of the craft, presently, "I think we'd better make a descent, if given the chance."

"You spoke of that before," remarked his companion, anxiously. "What is the reason for doing it, Frank?"

"Oh, nothing serious," replied the other. "We will then be at the parting of the ways, you know."

"You mean we'll be about to leave the river that will have been our guide up to then?" asked Andy.

"Yes," Frank admitted. "And from that time forward we must simply depend on our judgment for everything. In that event it might be well if we looked over the entire plant, to make sure everything was in apple-pie shape."

Andy breathed freer.

"Oh, I agree with you there," he hastened to say; "and I'm glad you hadn't any more serious reason. But did you ever see such a picture in all your born days? Just look at the forest bordering the river. Think of trying to push through such a dense mass of over-grown jungle. And I bet it's just full of snakes, poisonous spiders, lizards and all such things."

"Not to mention such trifling citizens as jaguars, ocelots, tapirs, alligators, crocodiles and their kind," laughed Frank.

"Ugh! what lucky fellows we are to be away up here, where we can skim along at the rate of thirty miles an hour easily, without half trying, and snap our fingers at all those things. I tell you, Frank, this aviation business is the greatest thing that ever came down the pike."

So they continued from time to time to converse as they kept pushing along, following the winding course of the swollen river that could be plainly seen below, between its banks of forest.

Frank did not soar high at this time. There seemed no need, and besides, both of the boys were deeply interested in watching the various changes that kept taking place in the checkerboard landscape below.

Several times during the first hour they passed over hamlets or villages. On such occasions it was ludicrous to observe the excitement that occurred. The Bird boys would not have been true to their nature had they not enjoyed the tremendous sensation which the sudden and unheralded appearance of the aeroplane caused in these river settlements.

Loud shouts floated up to them that constantly grew in volume. Men yelled, women and children screamed. Many fell flat on their faces; others tried to conceal themselves, as though they belonged to a covey of wild ducks over which a hungry eagle hovered, picking out his contemplated dinner.

And the last thing Andy would see, as he looked back, would be wildly running figures gesticulating furiously and evidently next door to crazy with excitement. Apparently these natives believed that the aeroplane must be a visitor from another world, or else some monster bird of a family long understood to be extinct.

The second hour had nearly ended and everything seemed to be moving along smoothly. Frank saw not a cloud on the horizon thus far. Surely this augured well for the ultimate success of their strange expedition.

Suddenly he heard Andy give vent to a cry of alarm.

"What is it?" he demanded, quickly.

"Turn her upward, quick! They are going to shoot at us!" shouted the other.

Frank instantly started to obey, and while their forward progress still continued unabated, the aeroplane commenced to head toward a higher altitude.

Immediately he heard the dull report of a gun from below. He dared not bend his head to look, since all his attention was needed to take care of his machine at such a critical moment. But the whine of the bullet as it passed close by was very plainly heard.

Then came other shots, many of them, and the air seemed full of strange hissing sounds. Twice Frank felt a slight shock that told him some part of the aeroplane had been struck by one of the flying missiles. His heart seemed to jump almost into his mouth, as he trembled for the result. But nothing happened. The motor kept up its insistent humming, and there was not a quiver to indicate that a vital part of the monoplane had been injured.

"Andy, are you hurt?" he called, after the volley had ceased, the marksmen below having evidently exhausted their ammunition.

"Only a scratch," came the reply. "Hardly drew blood. Think a splinter from the wood where a spent bullet zipped past must have hit me. It's all right, Frank! We ran the gantlet just fine. But all the same I guess it would be better for us to keep a little higher after this."

"Did you make them out and were they government troops, do you think?" Frank asked, for though he managed to turn his head, already had they made such speed that only the interminable forest could be seen in their rear.

"No," returned his comrade. "I just reckon it was another camp of these insurrectos. You remember the senor said there were apt to be more than one crowd of them up the river. It's the only way to get in and out of this country, and everything that happens has to count on a water route. I guess the Magdalena is about the same to this part of Colombia that the old Nile is to all Egypt."

"Well, it was a narrow escape, all right," Frank declared. "I don't just like the sound of those bullets all around when you're six or eight hundred feet up in the air."

Andy had recovered from his recent fright by now and could even laugh.

"I should say nix," he observed; "especially when you know that one little clip on either wing would upset us like a stone. Excuse me, if you please. I'll never be fully happy when flying until we invent some sort of little parachute that in case of a drop will give a fellow a chance for his money."

Another hour passed, when Frank declared they had now reached the point where a descent would be advisable in case they found an opening that looked suitable.

"There are the mountains over yonder on the right," he said, "and from now on we had better begin to scour the country, covering every mile just as though we had a comb and meant to explore it all."

The chance to drop came presently, and as the opening proved everything they could desire, a landing was made without the least trouble. Here they rested and partook of a light lunch, having brought plenty of provisions along, together with a gun of the latest repeating type, with which Colonel Josiah had presented them.

Frank, upon looking the aeroplane over a little later, discovered that he had been wise in deciding to make a halt. There was need of some attention. Certain parts had become weakened by the strain, either in the long voyage and handling on board the steamer, or else in this new flight.

He was determined to be thorough in all he did, and this consumed more or less time, so that when he finally pronounced the monoplane in perfect condition the afternoon was half gone.

Still, they must go up and put in an hour or two searching. Andy was too wild with impatience to hear of anything else, and Frank saw no reason for not complying.

"But we must be sure to get down again before night comes," he remarked, after they had made a successful rise and were speeding above the top of the thick forest. "If we should be caught out at night I rather guess it would be a serious piece of business." And Andy agreed with him.

For quite a time they soared aloft, Andy using the binoculars almost constantly, watching the country below and occasionally sweeping the distance.

Frank was thrilled to hear his chum suddenly give utterance to a cry, but it was more of amazement than delight that gave birth to this ejaculation.

"What is it now, Andy; more insurrectos?" he demanded, ready to manipulate the planes and strike for higher regions.

"No, no, not this time," came the quick reply; "but Frank, as sure as you live, there's that plagued old biplane just rising up yonder a mile away. And somehow I seem to feel that it spells trouble for us."



CHAPTER XVI.

THE AIR CHASE.

One hasty glance told Frank that there could be no mistake. Only too well did he know the construction of that same biplane that had in the near past competed with them for honors in the race for Old Thunder Top's crown.

"You're right, Andy," he said, earnestly; "and it seems to me they're heading for us right now. What do you make them out to be? Can you see who is handling the wheel? Is it Puss Carberry?"

"Yes, I'm dead sure of that; but Frank, there's somebody else with him!"

"Sandy?" asked his chum.

"No, it can't be. There, I had a good look at him, and Frank, he's got a beard! It's a man!" answered Andy, in tense tones.

Frank's first action was to move a lever that would change their course and place the biplane directly behind them. His next was to throw on more speed, so that the faithful little motor started to humming with the old-time rapidity that reminded Andy of the occasion when they put it to its best efforts in order to rush ahead of their rival of the air.

"Then we must guess from that Puss and Sandy have fallen into the hands of the rebels, since there are no government troops up here, the senor said," he observed, presently. "Are they gaining on us now, Andy?"

"I don't think so," replied the one who held the glass, "though Puss seems to be getting a whole lot of speed out of his Gnome engine right now. Reckon he must have overhauled it, or else found some way to put her up another notch."

"How strange to think that our old rivalry is being renewed away down here in this country, thousands of miles from home," remarked Frank, after a while.

"Huh! seems to me there would be something doing if you happened to run across Puss Carberry at the other side of the world," declared Andy.

The race kept up for some time, neither seeming to gain to any appreciable extent. Of course both boys were keyed up to a state of intense nervousness. Passing through the air at this fearful speed fully five hundred feet above the ground was surely enough to excite them. One little accident and they would hardly know enough to give a single shout of horror before the end must rush upon them. And yet Frank appeared as cool as though sitting beside a camp fire, laying out some contemplated air cruise on paper.

Andy was full of complaints.

"Aw, now, whatever do you suppose those measly old insurrectos want to chase us for in this style?" he growled. "We're attending to our private business and not bothering them one little bit. Why don't they leave a fellow alone? Goodness knows we've just got trouble enough on our hands without this."

"I don't know," said Frank, reflectively, "but I reckon they either want our monoplane or else believe we're in the employ of the government, and have been sent up here to spy on their movements. Anyhow, it seems plain that they mean to make a big effort to get us."

"Which they won't, if we know it!" cried Andy. "But see here, Frank, that chap is nervy, all right, going up with Puss and standing all this racket. A tenderfoot is generally rattled even with a slow flight. He seems to be holding out."

"I've been thinking about that," replied his chum. "And Andy, it looks to me as if that fellow must know something about aviation. If I could only glimpse him through the glasses I'd soon tell, for he'd show it by the way he sits there alongside Puss. A new beginner would be hugging the upright for dear life, and showing all the signs of fear."

"Yes, I know, because I did that same," answered Andy, once again raising the binoculars as he twisted his head around.

"How is it?" asked Frank.

"Not much signs of fright about him, as far as I can see," came the ready reply.

"Then make up your mind he's been up in an aeroplane before. Perhaps he's some French or German, who has thrown his fortunes in with the man who wants to sit in the presidential chair at Bogota, and in his own country he must have seen something of aviation. Oh, well, it doesn't make much difference to us. We just have to keep them at a distance and take our chances."

"But Frank—"

"Yes, I know what you're going to say, Andy; that night will soon be coming swooping down on us. That's so, and I'm sorry in one way, for it's going to be a tough old job finding a suitable place to fold our wings on in the darkness. But we're up against it good and hard, you see, and it's what you might call Hobson's choice."

Andy showed more positive signs of anger.

"What business have they got bothering us this way?" he grumbled. "Say, don't you suppose it would be all right for me to try a few shots at 'em with the fine Marlin repeating rifle we're carrying? Perhaps I could give 'em a scare anyhow and make 'em haul off."

"No, I wouldn't think of it," replied Frank, hastily. "You might cause trouble to our own delicately balanced little aeroplane by firing. And then again, what if you brought about an accident and sent them down to the earth like so many stones?"

"But you know those other chaps banged away at us and they didn't bother their heads a cent whether they upset our whole business or not," objected Andy, belligerently.

"Two wrongs never make a right, Andy."

"But when they opened fire on us," the other went on, complainingly, "that constituted a declaration of war, and so you sec, we'd be quite justified in giving 'em back the same kind of medicine."

"You forget that one of those two in the biplane is a former schoolmate of ours and that perhaps he's just being compelled to chase us right now," said Frank.

"Think so, do you?" growled Andy, above the rattle of the exhaust; "well, I'd like to warrant you that Puss Carberry is grinning right now, because of the fright he thinks he's giving us. No, sir, he's only too willing to do anything to upset our plans. I know him pretty well, and I wouldn't put any meanness past that fellow."

Frank in secret did begin to feel more than anxious. The afternoon was almost over and the sun perilously near the western horizon. Too well did he know how rapidly darkness came after the disappearance of the king of day.

He bade Andy pay more attention to the lay of the country ahead of them.

"We're keeping well ahead of the biplane," he observed, "and there's little danger of their overtaking us. But in case they drop out of the race we must try and know something of the chances for a landing ourselves."

"Gee! it looks pretty punk down there!" admitted Andy, after he had carefully turned the glasses forward and down.

"That's what is bothering me," Frank said. "We've sure got to drop, sooner or later, because it would be utterly impossible for us to keep afloat all night. And if there happens to be no opening in that dense forest, how can we land?"

"Listen! as sure as you live they're trying to wing us with a shot!" cried Andy.

"Well, I wouldn't bother about that. The fellow only has a revolver, if I know the sound of one, and he could never reach us at this distance. It tells me that he's got to about the limit and that something is going to change pretty soon, mark my words, Andy."

Of course one of Frank's objects in saying this was to encourage his chum, for he knew that in all probability Andy was getting pretty close to what he himself would call a "blue funk."

Sure enough the reports continued until just six had reached their ears faintly.

"That ends it," observed Frank, complacently.

"And he never touched us," echoed his cousin, evidently with more or less relief.

"Now take a look back and see what they are doing, Andy."

"H'm! still coming right along at top-notch speed," replied the other.

"All right. There's going to be a change soon. Look down, Andy."

"Oh, Frank, what a dandy open space! If only that plagued biplane was in Guinea, how easy we could spiral down and make a landing there!"

"Yes!" said Frank, "And, mark me, that is just what they intend doing. As for us, we'll have to move along further into the wilderness and hope that another chance will come to let us out before everything is blotted from sight by utter darkness."

"Frank, they've just sighted the open spot!" cried Andy, a few seconds later.

"All right, what did I say?" demanded his cousin.

"They've given up the chase, sure!"

"And are about to drop down to make a landing for the night; is that so?" asked Frank, eagerly, for their own chances were getting poorer with every passing minute and secretly he was more worried than he chose to admit.

"Just what they're doing right now, beginning to spiral down. Puss and his old biplane weren't in it again with our dandy little Bug. There they go, Frank. Don't I wish we had as good a place to grab hold of the old earth!"

"Well," Frank continued, gravely, "turn around and look your prettiest for it, then. Don't let even a half way decent spot go by. Any port in a storm, the sailor says, and that ought to apply to the airship tar just as well. See anything yet, Chum Andy?"

"N-no, can't say that I do," came the reply, as the other eagerly bent his gaze on the tree tops that they were beginning to approach closer, for Frank had turned the lever of the deflecting rudder in order to start the monoplane earthward.

And the more they dropped the lower the sun seemed to get, until part of his glowing disc appeared to touch the horizon.

Already it was growing dusk below them, and the dense foliage of the interlocked branches of the trees seemed to offer an insuperable barrier to a successful landing.



CHAPTER XVII.

THE CAMP IN THE TROPICAL JUNGLE.

"Frank, this is tough luck!" Andy exclaimed, presently.

"Keep up your spirits, old fellow!" called out the other, cheerily. "Has the biplane succeeded in making a landing yet?"

"I guess so," replied Andy, moodily. "Can't see any sign of her back there. And besides, it's actually getting dark down below, even while we can see a bit of the sun up here."

"That's because of the contrast. I'll drop still lower, so we'll just clear the top of the forest. Then you won't need the glasses, Andy. Both of us must keep a clever lookout for a chance. Every now and then there happens to be some opening in the forest, you know."

"Don't I hope we find one, though," declared the other. "Oh, wouldn't it be too mean for anything, Frank, if we smashed the precious little machine just when we are at the last stage of our big undertaking? If I lived through it I'd be broken hearted sure."

"Look, then," said Frank, earnestly, "and you take the right, while I keep an eye on the left. Both of us can watch out ahead. If it comes at all to be of any use, it's got to be found inside of the next five minutes!"

"So soon as that?" echoed the other, in distressed tones. "Oh, I'm afraid we're in for the very worst experience we ever met up with."

"Ha! hold on, Andy. What's that dead ahead?" cried Frank, who suddenly decreased the speed of the little motor.

"It's an opening of some sort, though awful little!" ejaculated Andy. "We can never do it, I'm afraid, Frank."

"We've just got to, no matter what chances we take. Hold hard now and if you can jump out in time, help stop her before we wreck her against a tree."

Even while speaking the air pilot was starting to drop down. He had made a specialty of this part of the business, knowing how very important it must always be to aviators. The rise was nothing compared to the descent, for many a gallant aircraft has been injured or even wrecked by clumsy manipulation, want of room or some other cause while landing after a flight.

Andy gripped hold of an upright. He tried to see down into that little slash in the great forest, as though it might hold every hope connected with his fortunes and the success or failure of his mission of mercy.

"Oh, be careful, Frank!" he called, as they just barely missed the top of a great tree.

There was no need of saying this, as Andy ought to have known. No one could possibly be more careful than Frank Bird. And yet this was one of those times when daring had to go hand in hand with caution. The space in which they meant to try for a landing was so very small that it seemed necessary for the aeroplane to come down almost as lightly as a feather.

Fortunately the youthful pilot possessed a good pair of eyes. And the gloom had not as yet entirely blotted out all features of the landscape, now that they were so close to the earth.

Andy was holding himself in readiness. He knew that there would perhaps be an opportunity for him to drop to the ground and by pulling back, help to bring the little airship to a full stop before they banged up against a tree at the further side of the little glade.

Never before had Andy found himself compelled to do such a queer "stunt," as he afterwards termed it; but he was braced to exert himself now to the best of his ability.

"Jump!" shouted Frank, as they came roughly in contact with the ground.

And Andy went. He never knew whether he jumped purposely or lost his grip of that upright after the shock of the collision; but the next thing he realized he was straining himself with might and main to hold back the monoplane, already gliding along with sundry violent bumps, on the three bicycle wheels.

"Hurrah! What did I say?" cried Frank, as the aeroplane came to a complete standstill close to the other border of trees.