biplane in the opening!" was what he cried.

Yes, Frank himself had sighted it now, but the discovery came too late
to have any effect upon their movements, since they were bound to land,
not having room to rise again, even did they wish to do so.

And Frank, as he felt the wheels under the aeroplane touch the earth,
also heard a loud cry and some lusty Spanish expletives as a pistol was
discharged.

CHAPTER XXIII.

HOMEWARD BOUND--CONCLUSION.

As was his usual habit, Andy jumped before the monoplane had
stopped. Frank on his part had no sooner seen that everything was going
well than he snatched the Marlin rifle from its fastenings. He realized
that they were up against trouble of some sort, for those Spanish
exclamations told him there must be one revolutionist at least close by
ready to do battle.

"Frank, look out, he's got a pistol!" cried a voice, which he recognized
as belonging to Puss Carberry.

Just then he caught sight of a figure rushing forward. It was the same
man no doubt whom they had seen with Puss in the biplane. They had
evidently broken some important parts in landing and ever since must
have been busy trying to mend the same.

"Stop!"

When the advancing revolutionist heard this sharp command and saw that
he was being covered by a rifle in the hands of the determined looking
pilot of the monoplane, he sized up the situation and then raised his
hands in a way that meant he surrendered.

"Drop that gun then!" ordered Frank, and as he did so Puss seized upon
it with a snarl of joy.

"Now we'll see how two can play at that game, you skunk!" gritted the
other, as he snapped the pistol straight at the head of the man.

"Here, none of that, Puss. You leave him to us. He's our prisoner, not
yours!" ordered Frank, horrified at the rage which the other had shown.

So Puss found that he did not have any authority in the matter, and that
if he wanted to get assistance from his old-time rivals in order to
finish mending his airship and get away from so dangerous a locality he
must do what they said.

He told about how he and Sandy had been out for a trial spin two days
before. That was when Frank and his chum had sighted them from the
river. But that very night some of the revolutionists had made a descent
on the home of his uncle, who had a cocoa plantation not many miles away
from that of Mendoza, seized him and carried him away, as they also did
the little airship.

Threatened with