“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.