But in this the leader of the party of adventurers turned out to be wrong, for when they awoke the next morning the grove did not contain the professor or his red wagon. Only the ashes of his fire were there to tell of his sojourn. But on one of the trees they found pinned a note.

"Sorry to leave so abruptly, but circ.u.mstances compelled. Perhaps we shall meet again. Who knows!"

And that, for many days, was to be the last they saw of the professor. When they re-encountered him--but of the surprising circ.u.mstances under which this was to take place we shall learn later.

CHAPTER VIII

A DESERT FIGHT

There was too much before them for the party to spend much time in speculation concerning the professor's sudden disappearance.

Immediately after breakfast Mr. Bell called the boys aside and said:

"How long will it take to get an aeroplane ready?"

The question came briskly, as did all Mr. Bell's speeches.

"I think I can promise to have a machine ready for flight by noon,"

was Roy's rejoinder after a brief interval of thought.

"Good! In that case we will waste no time in getting to work. I am anxious to reach the mine and stake it out properly for claim filing purposes. The less delay the better."

It was news to both boys that the definite legal claim to his discovery had not yet been made by Mr. Bell.

"Well, at any rate you are not likely to be bothered by claim jumpers away off here," commented Roy.

"No, I hardly think so," was the response, "but in these matters one cannot be too careful. Since the news spread that I have struck it rich there are men capable of enduring any hardship if there exists a possibility of wresting it from me."

"I should have thought that in order to be on the safe side you would have filed your claim before you came East," put in Peggy, who had joined the little group of consultants.

"I would have done so were it not for the fact that to have filed my claim and given the location would have set on my track the entire, restless gold-seeking horde that hangs about desert towns," said Mr.

Bell, with some warmth. "It is an outrageous thing, but nevertheless a fact, that the moment one files a claim it becomes public property. In my opinion the government should protect the locator of a gold find."

"But would that be quite fair to the others," said Peggy softly.

"Shouldn't everybody have an opportunity to develop natural resources?"

Mr. Bell gazed at her admiringly.

"You are right, my dear, and I'm a selfish old bear," he said, "but just the same, not all gold-seekers make desirable neighbors. Many desperate men are among them."

Peggy's mind wandered back to that midnight conversation she had overheard on the porch of the National House. But the same dread of ridicule that she had experienced then still held her, and she refrained from mentioning it.

By noon, with such good will did they work, that not only was one of the monoplanes erected and ready for flight, but a second was partially a.s.sembled, and only required the finishing touches to be in readiness for its aerial dash. While the boys, with the girls eagerly helping them, worked on the flying machine, Mr. Bell carefully studied a map he had made of the mine's location, and tested his compa.s.s. This done he--as sailors say--"laid out a course" for himself. From the springs the mine lay about due southeast and some hundred and twenty miles away.

In case of accidents the mining man traced carefully a second map, which was to be left behind in the camp so as to be constantly available in case anything happened to the first one, it had been decided that Jimsy, who by this time had become quite a skillful aviator, was to accompany Mr. Bell in the preliminary flight.

Roy and Mr. Peter Bell were to be left in charge of the camp, and in the event of the first aeroplane not returning that night the second, one was to be dispatched in search of it.

As an old plainsman, Mr. Bell had not laid his plans without taking into consideration the possibility of accident to the aeroplane, and none realized better than he did what serious consequences such an accident might have.

In the cha.s.sis of the machine with the travelers were placed a stock of canned goods, a pick and shovel and several hundred feet of fine but tough rope. A supply of water in stone jars and an extra stock of gasoline were also taken along. At the conclusion of the noon meal the motor was started and found to be working perfectly.

Nothing then remained to be done but to bid hasty "au revoirs" and wing off across the barren wastes.

"If all goes well we may be back to-night," said Mr. Bell as he slipped into the seat set tandem-wise behind Jimsy.

"And if not?" inquired Roy.

"In that case," and Mr. Bell's voice held a grave note, "in that case you will take the other monoplane and start out to look for us."

The roar of the motor as Jimsy started it drowned further words.

Blue smoke and livid flames burst from the exhausts. The structure of the flying machine shook and quivered under the force of the explosions. The next instant the first aeroplane to invade the Big Alkali scudded off across the level floor of the desert, and after some five hundred feet of land travel soared upward. In fifteen minutes it was a fast diminishing speck against the burnished blue of the Nevada sky.

There was some feeling of loneliness in the hearts of those left behind as they turned back toward the camp under the straggly willows. But this was speedily dissipated by that sovereign tonic for such feelings-namely, work. Much was to be done on the remaining monoplane, and with the exception of brief intervals of "fooling" the young people spent the rest of the day on finishing its equipment. Sunset found the machine ready for flight and the girl aviators and Roy very ready indeed for the supper to which Peter Bell presently summoned them by loud and insistent beating on a tin pan.

You may be sure that as the sun dipped lower, the sky toward the southwest had been frequently swept by expectant eyes, but supper was served and eaten, and the purple shadows of night began softly to drape the glaring desert and still there came no sign of the homing aeroplane.

"Reckon they don't want to risk a night flight and so have decided to camp at the mine," suggested old Peter Bell in response to Miss Prescott's rather querulous wondering as to the reason of the non-return.

"That must be it," agreed Roy easily, demolishing the last of a can of chicken.

Truth to tell, inwardly he had not expected the travelers back that night, and perhaps there lingered, too, in his mind, a faint desire to test out the other aeroplane in a task of rescue, in the event of the one Jimsy was driving breaking down.

But when morning came without a sign of the missing monoplane speculation crystallized into a real and keen anxiety. It was determined to delay no longer but set out at once in search of it.

To this end the recently equipped airship was stocked with food and water, and shortly before noon Roy finished the final tuning up of the engine. The others watched him anxiously as he worked. It seemed clear enough that some real accident must have occurred to the other machine.

"James would never keep us in suspense like this," said Mr. Bell, "if he could reach us and relieve our anxiety."

Roy was just about to clamber into the cha.s.sis when Peggy and Jess, who had been missing for several minutes, emerged from their tent.

Each girl wore an aviation hood and stout leather gauntlets.

Plainly they were dressed for aerial flight. Roy gazed at them quizzically.

"I hate to disappoint you girls," he said, "but I've got to play a lone hand in this thing."

"No such thing," said Peggy in her briskest tones; "what if anything happened to you? Who would run the machine if we weren't along?"

"That's quite true, Roy," struck in Jess, "and besides if--if anything has gone wrong with Jimsy who has a better right to be near him than I?"

Roy looked perplexed.

"What am I to do, Aunt Sally?" he appealed, turning to Miss Prescott.

To Peggy's astonishment, as much as anyone else's, Miss Prescott did not veto their going.

"I think it would be great folly for you to go on an expedition of this kind alone," she said, addressing Roy. "As Peggy says, if anything went wrong what could you do alone?"