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 superst.i.tious 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 a.s.sistance 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 a.s.semble 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 alt.i.tude.

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 ma.s.s 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 pa.s.sed 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 alt.i.tude.

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 pa.s.sed 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."