"a.s.sistants? Yes, of course," replied Major Honeywell, "but they must be persons of discretion."

"My chum, Alan Hope, who will make the ascension with me, will be one, and a colored boy, Elmer Grissom, who has helped me prepare for all my flights, will be the other."

There was no dissent.

"When shall I make my report?" Ned added.

Major Honeywell and his friend conferred a moment.

"Will five weeks be enough time for your exploration?"

"I think so; perhaps less."

"Then we will meet you at the Coates House in Kansas City on the first day of August."

Senor Oje arose and lit a fresh black cigar.

"It will be well for you and Major Honeywell to talk over these things while I see my Chicago banker," said he. And with a good- natured "Adios, Senores," he left the apartment.

"Now, about this liquid hydrogen?" began Major Honeywell at once.

"Well," said Ned, "instead of ballast, I'm going to carry reserve hydrogen with me."

"And is that so difficult?" asked the Major.

"Impossible, if you try to carry material to make the gas," answered the boy.

"And so you are going to carry it in liquid form?"

"I'm going to try, although the making of liquid hydrogen is, so far, pretty much a theory. It has been made only under tremendous pressure and at minus 423 degrees Fahrenheit."

The Major whistled.

"That is so cold that ice is red hot comparatively," explained Ned.

"This work must be done, in Washington."

They discussed the balloon itself, and the car and the engine for propelling it; where these were to be made in the East, and how they were to be forwarded to Chicago as they were completed. Ned himself was to go East at once and remain there until the last thing was accomplished.

Ned's chum, Alan Hope, had just taken employment for the school vacation in a large sporting goods store not far from the hotel. A few minutes later Ned walked leisurely into this store and sought out the fire-arms department, where Alan was on duty.

"h.e.l.lo, Ned," exclaimed Alan, "what do you think of this?" And with a smile he handed him an automatic pistol he was inspecting.

Restraining himself, Ned looked it over carefully.

"It holds ten cartridges and it's a beauty," declared Alan.

Ned weighed it carefully in his hand. "What's it worth?" he asked with dignity.

"Eighteen dollars."

"I think we'll need three of them!"

Alan laughed.

"And there are a good many other things I think we shall need," went on Ned, soberly.

"This hot weather is pretty bad on some people," laughed Alan.

"But, by the way, who are 'we?"'

"You and Elmer Grissom and I," answered Ned carelessly.

"And where are we going?" continued Alan, who was not unused to Ned's joking.

"On a little run in a private car down into New Mexico."

Alan looked at him a moment and then determined to have the joke out.

"Then what are we going to do?" he asked, still laughing.

"Make a trip through an unexplored mountain region in the best dirigible balloon ever built."

Alan wondered just where the joke came in. "And then?" he continued.

"Discover enough hidden treasure of jewels and silver and gold to make us rich."

"Shall I get you a cabbage leaf and some ice water?" asked Alan.

"Get your father's consent that you can go; that'll be all,"

announced Ned and then, breaking into a laugh, he relieved the perplexed Alan by explaining what had just taken place. In ten minutes Alan had secured permission to be off for the remainder of the day and the two boys hurried away for luncheon, to revel in dreams of their great opportunity.

By night Mrs. Napier had consented, though with tears, to Ned's going, and later Alan's father reluctantly did the same. As Ned was to leave the next afternoon and had to see Major Honeywell and Senor Oje in the morning it was a busy evening that the two boys spent in Ned's workshop.

At one o'clock in the morning Alan's work in Chicago was outlined and Ned's needs in the East were all listed.

"And now," exclaimed the tired but exuberant Alan, "it is all arranged but the name. What are we to call the air ship?"

"The 'Cibola,'" answered Ned without hesitation, "the dream of the Spanish invaders and our hope of success."

CHAPTER V

A DINNER PARTY ON THE PLACIDA

The long, heavy, limited train on which the young air ship boys were at last embarked on their extraordinary mission pulled slowly out of the station.

Ned made a quick survey of the Placida. Coming out of the baggage end he pa.s.sed first into a drawing room. In this were two sections that opened up into four berths. Beyond the berths a pa.s.sageway led to a private stateroom. When the boys reached the stateroom, Elmer was standing at the door with a happy smile on his face.