that the creatures might be naturally winged and at the same time
of human origin. From his position Bradley could not see the
wings of his captor, nor in the darkness had he been able to
examine those of the second creature closely when it circled
before him. He listened for the puff of a motor or some other
telltale sound that would prove the correctness of his theory.
However, he was rewarded with nothing more than the constant
flap-flap.

Presently, far below and ahead, he saw the waters of the inland
sea, and a moment later he was borne over them. Then his captor
did that which proved beyond doubt to Bradley that he was in the
hands of human beings who had devised an almost perfect scheme of
duplicating, mechanically, the wings of a bird--the thing spoke
to its companion and in a language that Bradley partially
understood, since he recognized words that he had learned from
the savage races of Caspak. From this he judged that they were
human, and being human, he knew that they could have no natural
wings--for who had ever seen a human being so adorned!
Therefore their wings must be mechanical. Thus Bradley reasoned--
thus most of us reason; not by what might be possible; but by what
has fallen within the range of our experience.

What he heard them say was to the effect that having covered
half the distance the burden would now be transferred from one
to the other. Bradley wondered how the exchange was to
be accomplished. He knew that those giant wings would not
permit the creatures to approach one another closely enough
to effect the transfer in this manner; but he was soon to
discover that they had other means of doing it.