While the dumpy little geologist went once more to search for strange specimens, the boys readily set to work and in a very short time the camping equipment was placed on board the Wondership.

When the boys arrived at Yuma, Masterson found no difficulty in selling the camping outfit to old man McGee, who decided to make one more try to find the Three Buttes.

“Don’t you think you’re too old, and that the gold, after all, may not be there?” Tom asked the eccentric miner.

“Nonsense!” exclaimed McGee indignantly.  “As I tole you afore, it stands ter reason thar’s gold out thar, and ’at it war’ent up to Peg-leg Smith nor’n to Guv’nor Downey, nor’n to McGuire, nor’n to Dr. De Courcy, nor’n to any of ’em to find the Buttes, but as I says afore, I says ag’in—­’at ther good Lord never made nuthin’ thet wasn’t of some use.  Very well, then, the desert is good fer nuthin’ else but mineral wealth, and Providence made it so plagued hard ter git at so ’at all of us couldn’t git rich at once.  I’ve been arter the Buttes all me life, and this wack I’m goin’ to land it rich!”

The fanatical old prospector, chuckling gleefully and sucking his pipe, ambled away while Tom looked after him, shaking his head sympathetically.

“Look out!  Look out!” someone shouted in Tom’s ear.  “There’s a beauty, a wonder!”

Tom, startled, whirled about to see the professor, gazing intently at a small rock upon which one of Tom’s heels was resting.  The professor violently pushed him aside, out came his little hammer, and in a moment the new specimen was in his bag.  Then, the man of science, without looking up to see whom he had spoken to, pounced on another stone.

Tom could not help laughing outright at the professor’s queer ways and deep concentration on his pet hobby.

“What a funny world this is!” remarked Tom, still amused.  “Here is a man forever after rocks, rocks, and there goes a miner set upon becoming rich and discovering some imaginary mine.”

He saw Jack waving to him from the veranda of the hotel.

“Listen, Tom,” said his chum when they stood side by side, “I was thinking that it would be a splendid idea to send the Wondership to New York, and that from there we travel to Nestorville, via the air route.”

“Great!” cried Tom, delighted.  “But say, are we to take Masterson along?”

“Of course not,” replied Jack.  “He can go back to Boston on the train.”

“Good for you!” declared Tom, slapping his chum on the back.

“But I haven’t told you my main idea yet,” said Jack, smiling,

“What is that?” asked the other wonderingly.

“Can’t you guess?”

“No,” Tom began to say, and then the roguish twinkle in Jack’s eyes gave him a sudden inspiration.  “You don’t mean to use the Z.2.X. to send messages with while we fly nearer and nearer to our old home town?”

“That is exactly what I wish to do,” said Jack quietly.