But once they were afloat he realized that he had been borrowing needless trouble, for the gallant little aircraft just acted beautifully and seemed to be able to speed merrily along with two passengers almost as well as with but one.
Of course there were many chances for trouble. There always are when traveling in an aeroplane, since the least thing that goes wrong means a descent or a fall.
Frank tried no lofty flight. He kept close above the tree tops, content to make steady progress in the direction where his little compass told him they would find the river.
Once away from the mountainous country and they were able to descend to still lower levels, where the chilly air changed to hot, and there were signs of life among the trees below—birds, monkeys and other natives of the wilds showing themselves at times.
It must have been a glorious sensation to the old aeronaut to be thus speeding along in a modern, up-to-date airship, after his enforced idleness for so long. Again and again did he express himself in that way, as he gazed over the expanse of country, and then allowed his eyes to rest fondly on the form of his boy, more dear to his heart than ever after what had happened.
"I think I see an open place beyond," remarked Frank, after they had been moving something like two hours after leaving the high plateau. "And it might be wise while we have the chance to go down and look things over. Then we will feel fit for another spell of work."
Accordingly the aeroplane was headed downward. They circled the opening once or twice in order that the pilot of the aircraft might get his bearings perfectly, and then he headed for the ground.
Even as they were just approaching the earth Frank heard Andy give one of his customary exclamations, such as announced an important discovery.
"Frank, there's the 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.