"Why not?" hotly demanded Nort.
"Because we'd like to keep you here a while," Thorp went on. "I guess the professors would like to have you accept their hospitality a little longer."
"Is this true?" cried Nort. "Are we prisoners?"
"Well, that is rather a harsh word to use," said Professor Wright.
"But we feel we must detain you—at least for a while!"
CHAPTER XX
THE DIAMOND X BRAND
Nort and Dick admitted to one another, afterward, that at first they believed the two professors to be joking. They imagined that the cultured scientists were merely indulging in a bit of fun, from much of which they were necessarily barred while in the class room. But a sharp look at the faces of the men who were at the head of an expedition, conducting a mysterious search, showed the boys that earnestness was the keynote.
"You—you're going to keep us here?" questioned Dick.
"For a while, yes," said Professor Wright, and there was more snap and decision in his voice than before.
"It is much your own fault," added Professor Blair.