"Nothing would please me better," replied the other boy, quickly, his face lighting up with delight at the prospect of a long ride in the saddle, to be followed by days, and perhaps weeks, of roaming through that wonderland, where Nature had outdone all her other works in trying to heap up astonishing surprises. "So far as I'm concerned," Frank went on, "I've always wanted to visit the Grand Canyon, and meant to do it some day later on. Of course I've seen what the little Colorado has to show, because it's only a long day's ride off. Mr. Hinchman can, I reckon, give us some points about the place, and maybe even mention several smaller canyons where we might be likely to find Uncle Felix in Echo Cave." "Which I'll be only too happy to attempt," answered the gentleman from Mohave City; "and as I said before, I know considerable about the mysteries of the big hole in the desert, all of which is at your service. Somehow, the queer way that message in the floating bottle came to me, excited my curiosity; and I'll be satisfied if I can only have a hand in the finding of the noted gentleman who, as your father has been telling me, vanished in the midst of his fame." "And now, dad, please explain just what we are to do in case luck follows us in our hunt, and we run across the professor," said Frank. "You are to explain to him that the long option which he held on that San Bernardino mine will expire in one more month. The work had been going on in a listless way for three years. All at once some time back they struck a wonderfully rich lode, and vein has been followed far enough to show that it is bound to be a record breaker." "That sounds great!" declared the deeply interested Bob. "The mine couldn't be bought for a million to-day," continued the stockman; "and yet Uncle Felix is probably carrying around with him (for it couldn't be found at his home) a little legal document whereby it will become his sole property in case he chooses to plank down the modest sum of twenty thousand dollars by the thirtieth of next month!" "Whew! that's going some, eh, Bob?" exclaimed Frank, with a little whistle that accentuated his surprise. "Then if we are fortunate enough to find Uncle Felix before that time has expired, what shall we do, sir?" asked the precise Bob, who was always keeping an eye out for the legal aspect of things. "Coax him to accompany you to the nearest notary public, where he can sign his acceptance of the terms under which he holds the option on the San Bernardino. But if this happens after the thirtieth it is all wasted energy; for at midnight of that day, I happen to know, the option expires," the ranchman continued, somewhat impressively. Just as he finished speaking he suddenly turned toward the window, at which his keen vision had caught sight of a moving shadow, as though someone might have been crouching without, and listening. "Who is there at the window?" he called out, sternly.