In various parts of their country they had been spending their recent
vacations together. The list of books given at the beginning of this story
will indicate the various parts of the country in which they had met their
adventures.

At the present time, however, when this story opens, they were nearly two
thousand miles from home.

Across the continent they had journeyed together and together also they
had spent ten days viewing the wonders of the Grand Canyon of the
Colorado. The apparently perilous ride on the backs of donkeys down Bright
Angel Trail had been greatly enjoyed, as well as certain other inspiring
expeditions which the boys had made, sometimes in company with others and
sometimes with a single guide for the quartet.

So enthusiastic had the young travelers become over their experiences that
at last they had obtained the consent of their parents to make an
expedition of their own. Two guides were secured who were familiar with
the entire region and two strong skiffs were purchased. In these boats the
boys had planned to follow a part of the dangerous Colorado River. They
had no desire to incur the perils that belonged to many of its swirling
rapids and tossing waters. In other places, however, the river was
comparatively safe and there the boys planned to follow the course of the
stream with their strong and heavy little boats.

Inasmuch as Fred's father was a prominent railway official he had obtained
for the boys certain privileges which otherwise they might not have had.
Fred himself was the most enthusiastic member of the party. Shorter than
any of his comrades his weight was still nearly as great as any of the
four. His solid, sturdy little frame was capable of great endurance and