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