with me, both of you. I am going back to the aerostat, and I dare
not leave you boys behind. Come!"

Kind of heart and generally complaisant though uncle Phaeton was,
neither Bruno nor Waldo cared to cross his will when made known in such
tones, and without further remonstrance they followed his lead, slipping
away from the snug little observatory without drawing attention to
themselves from any of yonder busy horde.

Not until the trio was fairly within the gulch did the professor speak
again, and then but a brief sentence or two.

"Give me time to weigh the matter, lads. Possibly I may agree, but don't
try to hurry my cooler judgment, please."

Waldo gave his brother an eager nudge at this, gestures and grimaces
being made to supply the lack of words. But when, the better to express
his confidence that all was coming their way, the youngster attempted a
caper of delight, his foot slipped from a leaf-hidden stone, and he took
an awkward tumble at full length.

"Never touched me!" he cried, scrambling to his feet ere a hand could
come to his aid. "Who says I don't know how to stand on both ends at the
same time?"

Barring this little caper, naught took place on their way to the
air-ship; and once there, the professor heaved a mighty sigh, wiping his
heated face as one might who has just won a worthy race. But he betrayed
no especial haste in setting the flying-machine afloat and Waldo finally
ventured:

"Can we help you off, uncle Phaeton?"

But he was assured there existed no necessity for such great haste.

"In fact, it might be dangerous to start while so many of the Aztecs are
upon the lookout," came the unexpected addition. "I believe it would be
vastly better not to leave here until shortly before dawn, to-morrow."

It took but a few words further to convince the brothers that this idea
was wisest, and while the young fellows felt sorry to have their view
cut so short, neither ventured to actually rebel.

After all, the day was well-nigh spent, and, besides preparing their
evening meal, it was essential that their plans for the immediate future
should be shaped as thoroughly as possible.

Professor Featherwit had resolved to fetch Cooper Edgecombe to the scene
of interest, in order to give him at least a fair chance to solve the
enigma which was perplexing them all. Even so, he felt that no small
degree of physical danger would attend that presence, particularly if
it should really prove, as they cou