umanity.

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