for the start, and
the other from Jack to his father, who was a guest of Dr. Mays. Jack
gave full details of their plans and other information concerning the
trip, so that the three plotters, a few days before the expedition set
out, knew as much about it as the boys themselves.

Armed with this information, Masterson, Higgins and Compton had no
difficulty in getting money from their parents, all of whom would have
described themselves as "keen business men." As for Jupe, he was too
badly scared to say anything about the loss of the letters, and as
Masterson, after steaming them open and abstracting what he wanted of
their contents, posted them to their proper destinations, the boys
started out on their long journey west without the slightest idea that
anyone but themselves and one or two others knew of their plans.

The professor's going was not unaccompanied by difficulties. Miss
Melissa had insisted that if he was to accompany the expedition, she
was going along, too. This being manifestly impossible, the man of
science was driven to the subterfuge of placing a bag of fossils in
his bed to represent him. On the night of the start, Miss Melissa
looked into his room every few minutes to make sure he had not
escaped.

It was not till morning that she discovered that the man of science
had effected his escape through his bedroom window, climbing down a
latticework to the ground. At first she was half inclined to pursue
him, but thought the better of it when she read the note the professor
had left behind.

"Well," said Miss Melissa to her little maid, "there's one good
thing--he won't be cluttering up the house with old stones and rocks
for some time to come."

"What shall I do with them fossils what he put in his bed to make
believe it was him, miss?" asked the maid.

"You may throw them into the creek at the back of the house, Mary,"
said Miss Melissa, and went placidly about her dusting and sweeping
and "setting to rights."

But of all this, the professor, on the train speeding westward, was
blissfully unconscious. Perhaps even if he had known it, he would not
have cared much, for even his scientific mind was warmed and thrilled
by the prospect of the aerial search for the mineral treasures of
Rattlesnake Island.

CHAPTER XXIII.

ON THE BORDER LINE.

The long train of gray-coated coaches, filmed with the arid dust of
the desert, rolled into Yuma, the little town at the junction of the
Gila and